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rumdl_lib/rules/
md013_line_length.rs

1/// Rule MD013: Line length
2///
3/// See [docs/md013.md](../../docs/md013.md) for full documentation, configuration, and examples.
4use crate::rule::{LintError, LintResult, LintWarning, Rule, RuleCategory, Severity};
5use crate::utils::mkdocs_admonitions;
6use crate::utils::mkdocs_attr_list::is_standalone_attr_list;
7use crate::utils::mkdocs_snippets::is_snippet_block_delimiter;
8use crate::utils::mkdocs_tabs;
9use crate::utils::range_utils::calculate_excess_range;
10use crate::utils::regex_cache::{IMAGE_REF_PATTERN, LINK_REF_PATTERN, URL_PATTERN};
11use crate::utils::table_utils::TableUtils;
12use crate::utils::text_reflow::{
13    BlockquoteLineData, blockquote_continuation_style, dominant_blockquote_prefix, is_self_contained_display_math_line,
14    join_soft_break_lines, reflow_blockquote_content, split_into_sentences,
15};
16use pulldown_cmark::LinkType;
17use toml;
18
19mod block_builder;
20mod helpers;
21pub mod md013_config;
22use crate::rules::md030_list_marker_space::MD030Config;
23use crate::utils::is_template_directive_only;
24use block_builder::{Block, BlockBuilder};
25use helpers::{
26    extract_list_marker_and_content, has_hard_break, is_github_alert_marker, is_horizontal_rule, is_html_only_line,
27    is_list_item, is_setext_heading_text_line, is_setext_underline_content, is_standalone_link_or_image_line,
28    is_unwrappable_line, source_list_marker, split_into_segments, standalone_link_ends_paragraph,
29    trim_preserving_hard_break,
30};
31pub use md013_config::MD013Config;
32use md013_config::{LengthMode, ReflowMode};
33
34#[cfg(test)]
35mod tests;
36use unicode_width::UnicodeWidthStr;
37
38#[derive(Clone, Default)]
39pub struct MD013LineLength {
40    pub(crate) config: MD013Config,
41    /// MD030 list-marker spacing, applied when reflowing list items so the rewrite
42    /// uses the configured post-marker spacing rather than a hard-coded single
43    /// space. Defaults to MD030's defaults (a single space everywhere), which
44    /// reproduces the previous behaviour exactly. See [`MD030Config::expected_spaces`].
45    pub(crate) list_spacing: MD030Config,
46}
47
48/// Blockquote paragraph line collected for reflow, with original line index for range computation.
49struct CollectedBlockquoteLine {
50    line_idx: usize,
51    data: BlockquoteLineData,
52}
53
54/// A deliberately conservative MDG step candidate.
55///
56/// Gherkin keywords are localized, so recognizing the word after the marker is
57/// not reliable without the complete dialect table. MDG represents steps as
58/// unordered Markdown list items; withholding reflow from all such items in the
59/// flavor is safer than splitting a step and changing its Gherkin text.
60fn is_potential_mdg_step(ctx: &crate::lint_context::LintContext, line_num: usize) -> bool {
61    let Some(item) = ctx.list_item_on_line(line_num) else {
62        return false;
63    };
64    !item.is_ordered() && matches!(item.marker_char(), Some('*' | '-' | '+'))
65}
66
67/// Whether line `line_num` (1-based) is touched on either boundary by a code
68/// span crossing more than one line: a span containing the newline that ends
69/// the line before it, or the newline that ends it.
70///
71/// A renderer reads the line break inside a code span as one space, so such a
72/// line is code however it is spelled, and a `$$...$$` expression on it is no
73/// display block. A span that begins and ends on the line itself does not
74/// matter. `flags` holds one entry per line of the document, indexed here by
75/// the 1-based line number, and comes from
76/// [`crate::utils::text_reflow::lines_touching_multiline_code_span`], which
77/// reads code spans on their own rather than alongside math delimiters: a
78/// `$$...$$` pair closes wherever the next `$$` sits, backtick or not, so a
79/// backtick between them that in fact opens a span reaching past the line
80/// needs a parser that isn't also deciding where the math closes.
81fn line_touches_multiline_code_span(flags: &[bool], line_num: usize) -> bool {
82    line_num
83        .checked_sub(1)
84        .and_then(|idx| flags.get(idx))
85        .copied()
86        .unwrap_or(false)
87}
88
89/// Whether any of the lines `start_idx..=end_idx` (0-indexed) is a definition
90/// list's term, or a definition's marker line holding its text.
91///
92/// The container reflow paths join these into prose: a term is absorbed into
93/// the text around it, and a marker loses the spacing that sets the
94/// definition's content column. A definition's later paragraph is prose at
95/// the definition's indentation, which the paths keep, and a list or
96/// blockquote nested inside a definition holds none of these lines, so both
97/// still reflow.
98fn holds_definition_list(ctx: &crate::lint_context::LintContext, start_idx: usize, end_idx: usize) -> bool {
99    (start_idx..=end_idx).any(|idx| {
100        let line_num = idx + 1;
101        ctx.is_definition_term(line_num)
102            || ctx
103                .definition_text_at(line_num)
104                .is_some_and(|text| text.start_line == line_num && text.marker_prefix_len.is_some())
105    })
106}
107
108impl MD013LineLength {
109    pub fn new(line_length: usize, code_blocks: bool, tables: bool, headings: bool, strict: bool) -> Self {
110        Self {
111            config: MD013Config {
112                line_length: crate::types::LineLength::new(line_length),
113                code_blocks,
114                code_spans: true,
115                tables,
116                headings,
117                math_blocks: true,
118                bracket_display_math: false,
119                paragraphs: true,  // Default to true for backwards compatibility
120                blockquotes: true, // Default to true for backwards compatibility
121                strict,
122                stern: false,
123                heading_line_length: None,
124                code_block_line_length: None,
125                reflow: false,
126                reflow_mode: ReflowMode::default(),
127                length_mode: LengthMode::default(),
128                abbreviations: Vec::new(),
129                require_sentence_capital: true,
130                ignore_link_urls: true,
131                atomic_spans: true,
132                reflow_break_link_text: false,
133                reflow_length_exemptions: false,
134            },
135            list_spacing: MD030Config::default(),
136        }
137    }
138
139    pub fn from_config_struct(config: MD013Config) -> Self {
140        Self {
141            config,
142            list_spacing: MD030Config::default(),
143        }
144    }
145
146    /// Return a clone with code block checking disabled.
147    /// Used for doc comment linting where code blocks are Rust code managed by rustfmt.
148    pub fn with_code_blocks_disabled(&self) -> Self {
149        let mut clone = self.clone();
150        clone.config.code_blocks = false;
151        clone
152    }
153
154    /// Convert MD013 LengthMode to text_reflow ReflowLengthMode
155    /// Normalized set of reference labels defined in the document.
156    ///
157    /// Passed to reflow so a bare shortcut reference (`[text]`) is treated as an
158    /// atomic link only when its label is actually defined; an undefined
159    /// bracketed run reflows as literal prose.
160    fn defined_reference_labels(ctx: &crate::lint_context::LintContext) -> std::collections::HashSet<String> {
161        ctx.reference_definitions()
162            .iter()
163            .map(|d| crate::utils::text_reflow::normalize_reference_label(&d.id))
164            .collect()
165    }
166
167    /// Build the reflow options shared by every MD013 fix path.
168    ///
169    /// `line_length` varies per call site (some subtract a list-marker or
170    /// blockquote prefix); every other field is derived uniformly from the
171    /// effective config and the document flavor. Callers that need a different
172    /// `max_list_continuation_indent` override it via struct update.
173    fn reflow_options(
174        ctx: &crate::lint_context::LintContext,
175        config: &MD013Config,
176        line_length: usize,
177    ) -> crate::utils::text_reflow::ReflowOptions {
178        crate::utils::text_reflow::ReflowOptions {
179            line_length,
180            break_on_sentences: true,
181            preserve_breaks: false,
182            sentence_per_line: config.reflow_mode == ReflowMode::SentencePerLine,
183            semantic_line_breaks: config.reflow_mode == ReflowMode::SemanticLineBreaks,
184            abbreviations: config.abbreviations_for_reflow(),
185            length_mode: config.reflow_length_mode(),
186            attr_lists: ctx.flavor.supports_attr_lists(),
187            myst_roles: ctx.flavor.supports_myst_roles(),
188            require_sentence_capital: config.require_sentence_capital,
189            max_list_continuation_indent: if ctx.flavor.requires_strict_list_indent() {
190                Some(4)
191            } else {
192                None
193            },
194            defined_references: Some(Self::defined_reference_labels(ctx)),
195            atomic_spans: config.atomic_spans,
196            break_link_text: config.reflow_break_link_text,
197            length_exemptions: config.length_exemptions_for_reflow(),
198        }
199    }
200
201    fn should_ignore_line(
202        &self,
203        line: &str,
204        _lines: &[&str],
205        current_line: usize,
206        ctx: &crate::lint_context::LintContext,
207    ) -> bool {
208        if self.config.strict {
209            return false;
210        }
211
212        // Quick check for common patterns before expensive regex
213        let trimmed = line.trim();
214
215        // Only skip if the entire line is a URL (quick check first)
216        if (trimmed.starts_with("http://") || trimmed.starts_with("https://")) && URL_PATTERN.is_match(trimmed) {
217            return true;
218        }
219
220        // Only skip if the entire line is an image reference (quick check first)
221        if trimmed.starts_with("![") && trimmed.ends_with(']') && IMAGE_REF_PATTERN.is_match(trimmed) {
222            return true;
223        }
224
225        // Note: link reference definitions are handled as always-exempt (even in strict mode)
226        // in the main check loop, so they don't need to be checked here.
227
228        // Code blocks with long strings (only check if in code block)
229        if ctx.line_info(current_line + 1).is_some_and(|info| info.in_code_block)
230            && !trimmed.is_empty()
231            && !line.contains(' ')
232            && !line.contains('\t')
233        {
234            return true;
235        }
236
237        false
238    }
239
240    /// Check if rule should skip based on provided config (used for inline config support)
241    fn should_skip_with_config(&self, ctx: &crate::lint_context::LintContext, config: &MD013Config) -> bool {
242        // Skip if content is empty
243        if ctx.content.is_empty() {
244            return true;
245        }
246
247        // For sentence-per-line, semantic-line-breaks, or normalize mode, never skip based on line length
248        if config.reflow
249            && (config.reflow_mode == ReflowMode::SentencePerLine
250                || config.reflow_mode == ReflowMode::SemanticLineBreaks
251                || config.reflow_mode == ReflowMode::Normalize)
252        {
253            return false;
254        }
255
256        // Use the smallest applicable budget across line/heading/code-block
257        // contexts so a stricter context-specific limit doesn't get masked by
258        // the document-wide budget.
259        let min_limit = config.min_effective_line_length();
260        if min_limit.is_unlimited() {
261            return true;
262        }
263        let min_limit_bytes = min_limit.get();
264
265        // Quick check: if total content is shorter than the smallest line limit,
266        // definitely skip.
267        if ctx.content.len() <= min_limit_bytes {
268            return true;
269        }
270
271        // Skip if no line exceeds the smallest applicable limit.
272        !ctx.lines.iter().any(|line| line.byte_len > min_limit_bytes)
273    }
274
275    fn normalize_mode_needs_reflow<'a, I>(&self, lines: I, config: &MD013Config) -> bool
276    where
277        I: IntoIterator<Item = &'a str>,
278    {
279        let mut line_count = 0;
280        let check_length = !config.line_length.is_unlimited();
281
282        for line in lines {
283            line_count += 1;
284            if check_length && self.calculate_effective_length(line) > config.line_length.get() {
285                return true;
286            }
287        }
288
289        line_count > 1
290    }
291}
292
293impl Rule for MD013LineLength {
294    fn name(&self) -> &'static str {
295        "MD013"
296    }
297
298    fn description(&self) -> &'static str {
299        "Line length should not be excessive"
300    }
301
302    fn check(&self, ctx: &crate::lint_context::LintContext) -> LintResult {
303        // Use pre-parsed inline config from LintContext
304        let config_override = ctx.inline_config().get_rule_config("MD013");
305
306        // Apply configuration override if present
307        let effective_config = if let Some(json_config) = config_override {
308            if let Some(obj) = json_config.as_object() {
309                let mut config = self.config.clone();
310                if let Some(line_length) = obj.get("line_length").and_then(serde_json::Value::as_u64) {
311                    config.line_length = crate::types::LineLength::new(line_length as usize);
312                }
313                if let Some(code_blocks) = obj.get("code_blocks").and_then(serde_json::Value::as_bool) {
314                    config.code_blocks = code_blocks;
315                }
316                if let Some(code_spans) = obj.get("code_spans").and_then(serde_json::Value::as_bool) {
317                    config.code_spans = code_spans;
318                }
319                if let Some(tables) = obj.get("tables").and_then(serde_json::Value::as_bool) {
320                    config.tables = tables;
321                }
322                if let Some(headings) = obj.get("headings").and_then(serde_json::Value::as_bool) {
323                    config.headings = headings;
324                }
325                if let Some(math_blocks) = obj
326                    .get("math_blocks")
327                    .or_else(|| obj.get("math-blocks"))
328                    .and_then(serde_json::Value::as_bool)
329                {
330                    config.math_blocks = math_blocks;
331                }
332                if let Some(enabled) = obj
333                    .get("bracket_display_math")
334                    .or_else(|| obj.get("bracket-display-math"))
335                    .and_then(serde_json::Value::as_bool)
336                {
337                    config.bracket_display_math = enabled;
338                }
339                if let Some(blockquotes) = obj.get("blockquotes").and_then(serde_json::Value::as_bool) {
340                    config.blockquotes = blockquotes;
341                }
342                if let Some(strict) = obj.get("strict").and_then(serde_json::Value::as_bool) {
343                    config.strict = strict;
344                }
345                if let Some(stern) = obj.get("stern").and_then(serde_json::Value::as_bool) {
346                    config.stern = stern;
347                }
348                if let Some(v) = obj
349                    .get("ignore_link_urls")
350                    .or_else(|| obj.get("ignore-link-urls"))
351                    .or_else(|| obj.get("semantic_link_understanding"))
352                    .or_else(|| obj.get("semantic-link-understanding"))
353                    .and_then(serde_json::Value::as_bool)
354                {
355                    config.ignore_link_urls = v;
356                }
357                if let Some(reflow) = obj.get("reflow").and_then(serde_json::Value::as_bool) {
358                    config.reflow = reflow;
359                }
360                if let Some(reflow_mode) = obj.get("reflow_mode").and_then(|v| v.as_str()) {
361                    config.reflow_mode = match reflow_mode {
362                        "default" => ReflowMode::Default,
363                        "normalize" => ReflowMode::Normalize,
364                        "sentence-per-line" => ReflowMode::SentencePerLine,
365                        "semantic-line-breaks" => ReflowMode::SemanticLineBreaks,
366                        _ => ReflowMode::default(),
367                    };
368                }
369                config
370            } else {
371                self.config.clone()
372            }
373        } else {
374            self.config.clone()
375        };
376
377        // Fast early return using should_skip with EFFECTIVE config (after inline overrides)
378        // But don't skip if we're in reflow mode with Normalize or SentencePerLine
379        if self.should_skip_with_config(ctx, &effective_config)
380            && !(effective_config.reflow
381                && (effective_config.reflow_mode == ReflowMode::Normalize
382                    || effective_config.reflow_mode == ReflowMode::SentencePerLine
383                    || effective_config.reflow_mode == ReflowMode::SemanticLineBreaks))
384        {
385            return Ok(Vec::new());
386        }
387
388        // Direct implementation without DocumentStructure
389        let mut warnings = Vec::new();
390
391        // Special handling: line_length = 0 means "no line length limit"
392        // Skip all line length checks, but still allow reflow if enabled
393        let skip_length_checks = effective_config.line_length.is_unlimited();
394
395        // Pre-filter lines that could be problematic to avoid processing all lines.
396        // Use the smallest applicable budget across line/heading/code-block contexts
397        // so candidates aren't dropped when a stricter context-specific budget applies.
398        let prefilter_limit = effective_config.min_effective_line_length();
399        let prefilter_skip = prefilter_limit.is_unlimited();
400        let mut candidate_lines = Vec::new();
401        if !skip_length_checks && !prefilter_skip {
402            for (line_idx, line_info) in ctx.lines.iter().enumerate() {
403                // Skip front matter - it should never be linted
404                if line_info.in_front_matter {
405                    continue;
406                }
407
408                // Quick length check first
409                if line_info.byte_len > prefilter_limit.get() {
410                    candidate_lines.push(line_idx);
411                }
412            }
413        }
414
415        // If no candidate lines and not in normalize or sentence-per-line mode, early return
416        if candidate_lines.is_empty()
417            && !(effective_config.reflow
418                && (effective_config.reflow_mode == ReflowMode::Normalize
419                    || effective_config.reflow_mode == ReflowMode::SentencePerLine
420                    || effective_config.reflow_mode == ReflowMode::SemanticLineBreaks))
421        {
422            return Ok(warnings);
423        }
424
425        let lines = ctx.raw_lines();
426
427        // Whether a 1-indexed line is part of a heading. A setext heading's text
428        // is the whole paragraph its underline ends, and the parser records the
429        // heading itself only on the last of those lines, so the earlier ones
430        // are recognized through `is_setext_heading_text`. Both are O(1)
431        // per-line fields, so check them directly at each use site instead of
432        // materializing a full-document HashSet (an extra O(n) pass and
433        // allocation on a rule that runs on virtually every file).
434        let is_heading_line_num = |line_number: usize| -> bool {
435            line_number
436                .checked_sub(1)
437                .and_then(|idx| ctx.lines.get(idx))
438                .is_some_and(|line| line.heading.is_some() || line.is_setext_heading_text)
439        };
440
441        // Use pre-computed table blocks from context
442        // We need this for both the table skip check AND the paragraphs check
443        let table_blocks = &ctx.table_blocks;
444        let mut table_lines_set = std::collections::HashSet::new();
445        for table in table_blocks {
446            table_lines_set.insert(table.header_line + 1);
447            table_lines_set.insert(table.delimiter_line + 1);
448            for &line in &table.content_lines {
449                table_lines_set.insert(line + 1);
450            }
451        }
452
453        let defined_references = Self::defined_reference_labels(ctx);
454
455        // Process candidate lines for line length checks
456        'line_loop: for &line_idx in &candidate_lines {
457            let line_number = line_idx + 1;
458            let line = lines[line_idx];
459
460            // Calculate actual line length (used in warning messages)
461            let effective_length = self.calculate_effective_length(line);
462
463            // Pick the context-specific limit: heading > code-block > paragraph.
464            // Headings dominate over code-block context if a setext underline ever
465            // overlaps a fenced range (defensive — these are mutually exclusive in
466            // practice, but the explicit ordering documents intent).
467            let is_heading_line = is_heading_line_num(line_number);
468            let in_code_block = ctx.line_info(line_number).is_some_and(|info| info.in_code_block);
469            let line_limit = if is_heading_line {
470                effective_config.effective_heading_line_length().get()
471            } else if in_code_block {
472                effective_config.effective_code_block_line_length().get()
473            } else {
474                effective_config.line_length.get()
475            };
476
477            // A context-specific limit of 0 means "unlimited for this context".
478            if line_limit == 0 {
479                continue;
480            }
481
482            // Stern mode: like default, but the trailing-token forgiveness is
483            // disabled — a line with whitespace that exceeds the limit is a
484            // violation even if the excess is the final token. The "unwrappable"
485            // line exemption (single token, optionally prefixed by # or >) is
486            // still honored. Strict overrides stern entirely.
487            if effective_config.stern && !effective_config.strict && is_unwrappable_line(line) {
488                continue;
489            }
490
491            // Trailing-token forgiveness: only in default mode (not strict, not stern).
492            // If the line only exceeds the limit because of a long token at the end
493            // (URL, link chain, identifier), it passes. This matches markdownlint's
494            // behavior: line.replace(/\S*$/u, "#")
495            let check_length = if effective_config.strict || effective_config.stern {
496                effective_length
497            } else {
498                match line.rfind(char::is_whitespace) {
499                    Some(pos) => {
500                        let ws_char = line[pos..].chars().next().unwrap();
501                        let prefix_end = pos + ws_char.len_utf8();
502                        self.calculate_string_length(&line[..prefix_end]) + 1
503                    }
504                    None => 1, // No whitespace — entire line is a single token
505                }
506            };
507
508            // Skip lines where the check length is within the limit
509            if check_length <= line_limit {
510                continue;
511            }
512
513            // Ignore inline link/image URLs: suppress when excess comes entirely from inline URLs.
514            // Disabled by `strict` (all forgiveness off) and by `ignore_link_urls = false`
515            // (count link/image URLs toward the line length so such lines are flagged).
516            if !effective_config.strict && effective_config.ignore_link_urls {
517                let length_without_urls = self.length_without_inline_link_urls(effective_length, line_number, ctx);
518                if length_without_urls <= line_limit {
519                    continue;
520                }
521            }
522
523            // Inline code spans cannot be wrapped, so reflow cannot shorten a line
524            // whose excess length is one. When code-span checking is disabled,
525            // suppress a violation that would fit once inline code spans are excluded.
526            if !effective_config.code_spans {
527                let code_span_width: usize = ctx
528                    .code_spans()
529                    .iter()
530                    .filter(|span| span.line == line_number && span.end_line == line_number)
531                    .map(|span| self.calculate_string_length(&ctx.content[span.byte_offset..span.byte_end]))
532                    .sum();
533                if effective_length.saturating_sub(code_span_width) <= line_limit {
534                    continue;
535                }
536            }
537
538            // Skip mkdocstrings and pymdown blocks (already handled by LintContext)
539            if ctx.lines[line_idx].in_mkdocstrings || ctx.lines[line_idx].in_pymdown_block {
540                continue;
541            }
542
543            // Skip MyST comments (% comment) — structural lines, not prose
544            if ctx.lines[line_idx].is_myst_comment {
545                continue;
546            }
547
548            // Link reference definitions are always exempt, even in strict mode.
549            // There's no way to shorten them without breaking the URL.
550            // Also check after stripping list markers, since list items may
551            // contain link ref defs as their content.
552            {
553                let trimmed = line.trim();
554                if trimmed.starts_with('[') && trimmed.contains("]:") && LINK_REF_PATTERN.is_match(trimmed) {
555                    continue;
556                }
557                if is_list_item(trimmed) {
558                    let (_, content) = extract_list_marker_and_content(trimmed);
559                    let content_trimmed = content.trim();
560                    if content_trimmed.starts_with('[')
561                        && content_trimmed.contains("]:")
562                        && LINK_REF_PATTERN.is_match(content_trimmed)
563                    {
564                        continue;
565                    }
566                }
567            }
568
569            // Skip various block types efficiently
570            if !effective_config.strict {
571                // Lines whose only content is a link/image are exempt.
572                // After stripping list markers, blockquote markers, and emphasis,
573                // if only a link or image remains, there is no way to shorten it.
574                if is_standalone_link_or_image_line(ctx, line_number) {
575                    continue;
576                }
577
578                // Lines consisting entirely of HTML tags are exempt.
579                // Badge lines, images with attributes, and similar inline HTML
580                // are long due to URLs in attributes and can't be meaningfully shortened.
581                if is_html_only_line(line) {
582                    continue;
583                }
584
585                // Skip setext heading underlines
586                if !line.trim().is_empty() && line.trim().chars().all(|c| c == '=' || c == '-') {
587                    continue;
588                }
589
590                // Skip block elements according to config flags
591                // The flags mean: true = check these elements, false = skip these elements
592                // So we skip when the flag is FALSE and the line is in that element type
593                if (!effective_config.headings && is_heading_line_num(line_number))
594                    || (!effective_config.code_blocks
595                        && ctx.line_info(line_number).is_some_and(|info| info.in_code_block))
596                    || (!effective_config.tables && table_lines_set.contains(&line_number))
597                    || (!effective_config.math_blocks && self.line_is_display_math(line_number, ctx, &effective_config))
598                    || ctx.line_info(line_number).is_some_and(|info| info.in_html_block)
599                    || ctx.line_info(line_number).is_some_and(|info| info.in_html_comment)
600                    || ctx.line_info(line_number).is_some_and(|info| info.in_esm_block)
601                    || ctx.line_info(line_number).is_some_and(|info| info.in_jsx_expression)
602                    || ctx.line_info(line_number).is_some_and(|info| info.in_jsx_block)
603                    || ctx.line_info(line_number).is_some_and(|info| info.in_mdx_comment)
604                    || ctx.line_info(line_number).is_some_and(|info| info.in_pymdown_block)
605                {
606                    continue;
607                }
608
609                // Check if this is a paragraph/regular text line
610                // If paragraphs = false, skip lines that are NOT in special blocks
611                // Blockquote content is treated as paragraph text, so it's not
612                // included in the special blocks list here.
613                if !effective_config.paragraphs {
614                    let is_special_block = is_heading_line_num(line_number)
615                        || ctx.line_info(line_number).is_some_and(|info| info.in_code_block)
616                        || table_lines_set.contains(&line_number)
617                        || ctx.line_info(line_number).is_some_and(|info| info.in_html_block)
618                        || ctx.line_info(line_number).is_some_and(|info| info.in_html_comment)
619                        || ctx.line_info(line_number).is_some_and(|info| info.in_esm_block)
620                        || ctx.line_info(line_number).is_some_and(|info| info.in_jsx_expression)
621                        || ctx.line_info(line_number).is_some_and(|info| info.in_jsx_block)
622                        || ctx.line_info(line_number).is_some_and(|info| info.in_mdx_comment)
623                        || ctx
624                            .line_info(line_number)
625                            .is_some_and(super::super::lint_context::types::LineInfo::in_mkdocs_container);
626
627                    // Skip regular paragraph text when paragraphs = false
628                    if !is_special_block {
629                        continue;
630                    }
631                }
632
633                // Skip blockquote lines when blockquotes = false.
634                // Also skip lazy continuation lines that belong to a blockquote
635                // (lines without `>` prefix that follow a blockquote line).
636                if !effective_config.blockquotes {
637                    if ctx.lines[line_number - 1].blockquote.is_some() {
638                        continue;
639                    }
640                    // Check for lazy continuation: scan backwards through
641                    // non-blank lines to find if this paragraph started with
642                    // a blockquote marker
643                    if !line.trim().is_empty() {
644                        let mut scan = line_number.saturating_sub(2);
645                        loop {
646                            if ctx.lines[scan].blockquote.is_some() {
647                                // Found a blockquote ancestor — this is a lazy continuation
648                                continue 'line_loop;
649                            }
650                            if lines[scan].trim().is_empty() || scan == 0 {
651                                break;
652                            }
653                            scan -= 1;
654                        }
655                    }
656                }
657
658                // Skip lines that are only a URL, image ref, or link ref
659                if self.should_ignore_line(line, lines, line_idx, ctx) {
660                    continue;
661                }
662            }
663
664            // In sentence-per-line mode, check if this is a single long sentence
665            // If so, emit a warning without a fix (user must manually rephrase)
666            if effective_config.reflow_mode == ReflowMode::SentencePerLine {
667                let sentences = split_into_sentences(
668                    line.trim(),
669                    Some(&defined_references),
670                    effective_config.require_sentence_capital,
671                );
672                if sentences.len() == 1 {
673                    // Single sentence that's too long - warn but don't auto-fix
674                    let message = format!("Line length {effective_length} exceeds {line_limit} characters");
675
676                    let (start_line, start_col, end_line, end_col) =
677                        calculate_excess_range(line_number, line, line_limit);
678
679                    warnings.push(LintWarning {
680                        rule_name: Some(self.name().to_string()),
681                        message,
682                        line: start_line,
683                        column: start_col,
684                        end_line,
685                        end_column: end_col,
686                        severity: Severity::Warning,
687                        fix: None, // No auto-fix for long single sentences
688                    });
689                    continue;
690                }
691                // Multiple sentences will be handled by paragraph-based reflow
692                continue;
693            }
694
695            // In semantic-line-breaks mode, skip per-line checks —
696            // all reflow is handled at the paragraph level with cascading splits
697            if effective_config.reflow_mode == ReflowMode::SemanticLineBreaks {
698                continue;
699            }
700
701            // Don't provide fix for individual lines when reflow is enabled
702            // Paragraph-based fixes will be handled separately
703            let fix = None;
704
705            let message = format!("Line length {effective_length} exceeds {line_limit} characters");
706
707            // Calculate precise character range for the excess portion
708            let (start_line, start_col, end_line, end_col) = calculate_excess_range(line_number, line, line_limit);
709
710            warnings.push(LintWarning {
711                rule_name: Some(self.name().to_string()),
712                message,
713                line: start_line,
714                column: start_col,
715                end_line,
716                end_column: end_col,
717                severity: Severity::Warning,
718                fix,
719            });
720        }
721
722        // If reflow is enabled, generate paragraph-based fixes
723        if effective_config.reflow {
724            let paragraph_warnings = self.generate_paragraph_fixes(ctx, &effective_config, lines);
725            // Merge paragraph warnings with line warnings, removing duplicates
726            for mut pw in paragraph_warnings {
727                if ctx.flavor == crate::config::MarkdownFlavor::MDG
728                    && (pw.line..=pw.end_line).any(|line_number| is_potential_mdg_step(ctx, line_number))
729                {
730                    // Keep reporting the excessive line, but do not offer a fix
731                    // whose replacement would split a Gherkin step across lines.
732                    pw.fix = None;
733                }
734                // Remove any line warnings that overlap with this paragraph
735                warnings.retain(|w| w.line < pw.line || w.line > pw.end_line);
736                warnings.push(pw);
737            }
738        }
739
740        Ok(warnings)
741    }
742
743    fn fix(&self, ctx: &crate::lint_context::LintContext) -> Result<String, LintError> {
744        // For CLI usage, apply fixes from warnings
745        // LSP will use the warning-based fixes directly
746        let warnings = self.check(ctx)?;
747        let warnings =
748            crate::utils::fix_utils::filter_warnings_by_inline_config(warnings, ctx.inline_config(), self.name());
749
750        // If there are no fixes, return content unchanged
751        if !warnings.iter().any(|w| w.fix.is_some()) {
752            return Ok(ctx.content.to_string());
753        }
754
755        // Apply warning-based fixes
756        crate::utils::fix_utils::apply_warning_fixes(ctx.content, &warnings)
757            .map_err(|e| LintError::FixFailed(format!("Failed to apply fixes: {e}")))
758    }
759
760    fn as_any(&self) -> &dyn std::any::Any {
761        self
762    }
763
764    fn category(&self) -> RuleCategory {
765        RuleCategory::Whitespace
766    }
767
768    fn should_skip(&self, ctx: &crate::lint_context::LintContext) -> bool {
769        self.should_skip_with_config(ctx, &self.config)
770    }
771
772    crate::impl_rule_config_sections!(MD013Config);
773
774    fn config_aliases(&self) -> Option<std::collections::HashMap<String, String>> {
775        let mut aliases = std::collections::HashMap::new();
776        aliases.insert("enable_reflow".to_string(), "reflow".to_string());
777        aliases.insert("strict_sentences".to_string(), "require-sentence-capital".to_string());
778        aliases.insert("strict-sentences".to_string(), "require-sentence-capital".to_string());
779        // Kept in step with the `alias` attributes on `MD013Config::ignore_link_urls`.
780        // Serde accepts these spellings, so a config using one is honored; without
781        // them here the key validator reports a documented, working key as unknown.
782        aliases.insert(
783            "semantic-link-understanding".to_string(),
784            "ignore-link-urls".to_string(),
785        );
786        aliases.insert(
787            "semantic_link_understanding".to_string(),
788            "ignore-link-urls".to_string(),
789        );
790        Some(aliases)
791    }
792
793    fn from_config(config: &crate::config::Config) -> Box<dyn Rule>
794    where
795        Self: Sized,
796    {
797        let rule_config = MD013Config::from_document_config(config);
798        let mut rule = Self::from_config_struct(rule_config);
799        // Pull list-marker spacing from MD030 (via the shared serde config loader)
800        // so reflow rewrites list items with the configured spacing rather than a
801        // hard-coded single space.
802        rule.list_spacing = crate::rule_config_serde::load_rule_config::<MD030Config>(config);
803        Box::new(rule)
804    }
805}
806
807impl MD013LineLength {
808    /// True when `line_num` (1-indexed) sits inside a `$$` span covering more
809    /// than one line, as seen by the byte-level math parser.
810    fn line_in_multiline_math_span(&self, line_num: usize, ctx: &crate::lint_context::LintContext) -> bool {
811        ctx.math_spans()
812            .iter()
813            .any(|span| span.is_display && span.end_line > span.line && (span.line..=span.end_line).contains(&line_num))
814    }
815
816    /// True when `line_num` (1-indexed) holds nothing but display math, whether
817    /// that is one line of a multi-line block, a delimiter line, or a whole line
818    /// that is a single complete `$$...$$` span. This is what `math-blocks =
819    /// false` exempts from the length check.
820    ///
821    /// rumdl models math twice and the two models miss different containers, so
822    /// this consults both. `math_spans()` is byte-level and sees a block opened on
823    /// a list marker line (`- $$`), which the line-level map cannot because that
824    /// line does not begin with `$$`. `LineInfo::in_math_block` is line-level and
825    /// sees a four-space-indented block inside a footnote, which the byte-level
826    /// parser reads as an indented code block. Taking the union only ever adds
827    /// coverage: neither signal fires on ordinary prose, and an unmatched `$$`
828    /// opener is flagged by neither, so a stray delimiter cannot exempt the rest
829    /// of the document.
830    fn line_is_display_math(
831        &self,
832        line_num: usize,
833        ctx: &crate::lint_context::LintContext,
834        config: &MD013Config,
835    ) -> bool {
836        self.line_holds_only_multiline_math(line_num, ctx)
837            || ctx.line_info(line_num).is_some_and(|info| info.in_math_block)
838            || (config.bracket_display_math
839                && ctx
840                    .bracket_display_math_lines()
841                    .multiline
842                    .get(line_num.saturating_sub(1))
843                    .copied()
844                    .unwrap_or(false))
845            || (config.bracket_display_math
846                && ctx
847                    .bracket_display_math_lines()
848                    .standalone
849                    .get(line_num.saturating_sub(1))
850                    .copied()
851                    .unwrap_or(false))
852    }
853
854    /// True when a multi-line `$$` span covers `line_num` (1-indexed) and the line
855    /// holds nothing besides that math.
856    ///
857    /// A delimiter line can carry Markdown outside the delimiter: `$$ trailing
858    /// prose` closes a block and then continues in prose, and `leading prose $$`
859    /// opens one at the end of a sentence. That prose is ordinary text and counts
860    /// toward the line's length like any other, so exempting the whole line would
861    /// hide arbitrarily long prose behind a delimiter. The line-level map already
862    /// leaves such mixed lines unflagged; this is the byte-level half of the same
863    /// judgement.
864    fn line_holds_only_multiline_math(&self, line_num: usize, ctx: &crate::lint_context::LintContext) -> bool {
865        let Some(info) = ctx.line_info(line_num) else {
866            return false;
867        };
868        let line = info.content(ctx.content);
869
870        ctx.math_spans().iter().any(|span| {
871            if !span.is_display || span.end_line <= span.line || !(span.line..=span.end_line).contains(&line_num) {
872                return false;
873            }
874            if line_num == span.line {
875                let before = line.get(..span.byte_offset.saturating_sub(info.byte_offset));
876                if !before.is_none_or(|before| Self::only_structure_precedes_math(before, info)) {
877                    return false;
878                }
879            }
880            if line_num == span.end_line {
881                let after = line.get(span.byte_end.saturating_sub(info.byte_offset)..);
882                if !after.is_none_or(|after| after.trim().is_empty()) {
883                    return false;
884                }
885            }
886            true
887        })
888    }
889
890    /// True when the text before a block's opening delimiter is only the structure
891    /// the block sits in: indentation, a blockquote marker, or the list marker
892    /// introducing it. Such a block still owns its whole line.
893    fn only_structure_precedes_math(before: &str, info: &crate::lint_context::LineInfo) -> bool {
894        let after_marker =
895            crate::utils::blockquote::parse_blockquote_prefix(before).map_or(before, |prefix| prefix.content);
896        if after_marker.trim().is_empty() {
897            return true;
898        }
899        info.list_item.as_ref().is_some_and(|item| {
900            let mut chars = before.chars();
901            chars.by_ref().take(item.content_column).count() == item.content_column && chars.as_str().trim().is_empty()
902        })
903    }
904
905    /// True when `line_num` (1-indexed) falls inside a display-math block that
906    /// spans more than one line.
907    ///
908    /// Line breaks carry meaning inside such a block: a TeX `%` comment runs to
909    /// the end of its line, so joining the lines pulls whatever followed on later
910    /// lines into the comment and drops it from the rendered equation, which can
911    /// also leave an environment unclosed. Reflow therefore leaves these blocks
912    /// alone regardless of the `math_blocks` setting, which governs only whether
913    /// their length is reported.
914    ///
915    /// This is `line_is_display_math` minus the case of a whole line that is one
916    /// complete `$$...$$` span, which
917    /// [`crate::utils::text_reflow::is_self_contained_display_math_line`]
918    /// recognizes. Such a line is a block of its own: it has no internal line
919    /// breaks to lose, and reflow keeps it on the line it was written on
920    /// through that recognizer rather than through this one.
921    fn line_in_multiline_math_block(
922        &self,
923        line_num: usize,
924        ctx: &crate::lint_context::LintContext,
925        config: &MD013Config,
926    ) -> bool {
927        self.line_in_multiline_math_span(line_num, ctx)
928            || ctx.line_info(line_num).is_some_and(|info| {
929                info.in_math_block && !is_self_contained_display_math_line(info.content(ctx.content))
930            })
931            || (config.bracket_display_math
932                && ctx
933                    .bracket_display_math_lines()
934                    .multiline
935                    .get(line_num.saturating_sub(1))
936                    .copied()
937                    .unwrap_or(false))
938    }
939
940    fn line_is_standalone_bracket_math(
941        &self,
942        line_num: usize,
943        ctx: &crate::lint_context::LintContext,
944        config: &MD013Config,
945    ) -> bool {
946        config.bracket_display_math
947            && ctx
948                .bracket_display_math_lines()
949                .standalone
950                .get(line_num.saturating_sub(1))
951                .copied()
952                .unwrap_or(false)
953    }
954
955    /// True when `line_num` (1-based) sits inside a structure whose lines must be
956    /// preserved verbatim (code block, front matter, HTML/JSX/MDX block, MkDocs
957    /// container, div marker, multi-line math block, ...). Used to keep blockquote
958    /// reflow from touching quoted-looking text embedded in such structures.
959    fn line_in_verbatim_context(
960        &self,
961        line_num: usize,
962        ctx: &crate::lint_context::LintContext,
963        config: &MD013Config,
964    ) -> bool {
965        if self.line_in_multiline_math_block(line_num, ctx, config) {
966            return true;
967        }
968        ctx.line_info(line_num).is_some_and(|info| {
969            info.in_code_block
970                || info.in_front_matter
971                || info.in_html_block
972                || info.in_html_comment
973                || info.in_esm_block
974                || info.in_jsx_expression
975                || info.in_jsx_block
976                || info.in_mdx_comment
977                || info.in_mkdocstrings
978                || info.in_pymdown_block
979                || info.in_mkdocs_container()
980                || info.is_div_marker
981        })
982    }
983
984    fn is_blockquote_content_boundary(
985        &self,
986        content: &str,
987        line_num: usize,
988        ctx: &crate::lint_context::LintContext,
989        config: &MD013Config,
990    ) -> bool {
991        let trimmed = content.trim();
992
993        trimmed.is_empty()
994            || self.line_in_verbatim_context(line_num, ctx, config)
995            || trimmed.starts_with('#')
996            || trimmed.starts_with("```")
997            || trimmed.starts_with("~~~")
998            || trimmed.starts_with('>')
999            || TableUtils::is_potential_table_row_with_flavor(content, ctx.flavor)
1000            || is_list_item(trimmed)
1001            || is_horizontal_rule(content)
1002            // A setext underline ends the quoted paragraph. The text decides
1003            // it: under quoted paragraph text the run is an underline, a dash
1004            // run anywhere else is a thematic break, and stopping at an equals
1005            // run that is neither only leaves text unreflowed.
1006            || is_setext_underline_content(content)
1007            || (trimmed.starts_with('[') && content.contains("]:"))
1008            || is_template_directive_only(content)
1009            || is_standalone_attr_list(content)
1010            || is_snippet_block_delimiter(content)
1011            || is_github_alert_marker(trimmed)
1012            || is_html_only_line(content)
1013            || self.line_is_standalone_bracket_math(line_num, ctx, config)
1014            || standalone_link_ends_paragraph(ctx, line_num, config)
1015    }
1016
1017    #[allow(clippy::too_many_arguments)]
1018    fn generate_blockquote_paragraph_fix(
1019        &self,
1020        ctx: &crate::lint_context::LintContext,
1021        config: &MD013Config,
1022        lines: &[&str],
1023        start_idx: usize,
1024        line_ending: &str,
1025        // Extra indent (spaces) to prepend to the emitted `>` prefix so a blockquote
1026        // nested in a list item moves with its parent's widened marker. Zero unless a
1027        // non-default MD030 widened an ancestor list item.
1028        ancestor_shift: isize,
1029    ) -> (Option<LintWarning>, usize) {
1030        let Some(start_bq) = ctx.lines.get(start_idx).and_then(|line| line.blockquote.as_deref()) else {
1031            return (None, start_idx + 1);
1032        };
1033        let target_level = start_bq.nesting_level;
1034        let defined_references = Self::defined_reference_labels(ctx);
1035
1036        let mut collected: Vec<CollectedBlockquoteLine> = Vec::new();
1037        let mut i = start_idx;
1038
1039        while i < lines.len() {
1040            if !collected.is_empty() && has_hard_break(&collected[collected.len() - 1].data.content) {
1041                break;
1042            }
1043
1044            let line_num = i + 1;
1045            if line_num > ctx.lines.len() {
1046                break;
1047            }
1048
1049            if lines[i].trim().is_empty() {
1050                break;
1051            }
1052
1053            let line_bq = ctx.lines[i].blockquote.as_deref();
1054            if let Some(bq) = line_bq {
1055                if bq.nesting_level != target_level {
1056                    break;
1057                }
1058
1059                if self.is_blockquote_content_boundary(&bq.content, line_num, ctx, config) {
1060                    break;
1061                }
1062
1063                collected.push(CollectedBlockquoteLine {
1064                    line_idx: i,
1065                    data: BlockquoteLineData::explicit(trim_preserving_hard_break(&bq.content), bq.prefix.clone()),
1066                });
1067                i += 1;
1068                continue;
1069            }
1070
1071            let lazy_content = lines[i].trim_start();
1072            if self.is_blockquote_content_boundary(lazy_content, line_num, ctx, config) {
1073                break;
1074            }
1075
1076            collected.push(CollectedBlockquoteLine {
1077                line_idx: i,
1078                data: BlockquoteLineData::lazy(trim_preserving_hard_break(lazy_content)),
1079            });
1080            i += 1;
1081        }
1082
1083        if collected.is_empty() {
1084            return (None, start_idx + 1);
1085        }
1086
1087        let next_idx = i;
1088        let paragraph_start = collected[0].line_idx;
1089        let end_line = collected[collected.len() - 1].line_idx;
1090        let line_data: Vec<BlockquoteLineData> = collected.iter().map(|l| l.data.clone()).collect();
1091        let paragraph_text = line_data
1092            .iter()
1093            .map(|d| d.content.as_str())
1094            .collect::<Vec<_>>()
1095            .join(" ");
1096
1097        // A colon-led line with a line of the paragraph before it opens a
1098        // definition, and joining the lines would flatten the definition list
1099        // into prose. The paragraph's first line is prose whatever it starts
1100        // with, since a definition needs a term on the line before it.
1101        let contains_definition_list = line_data
1102            .iter()
1103            .skip(1)
1104            .any(|d| crate::utils::text_reflow::is_definition_list_marker(&d.content));
1105        if contains_definition_list || holds_definition_list(ctx, paragraph_start, end_line) {
1106            return (None, next_idx);
1107        }
1108
1109        let contains_snippets = line_data.iter().any(|d| is_snippet_block_delimiter(&d.content));
1110        if contains_snippets {
1111            return (None, next_idx);
1112        }
1113
1114        let needs_reflow = match config.reflow_mode {
1115            ReflowMode::Normalize => {
1116                self.normalize_mode_needs_reflow(line_data.iter().map(|d| d.content.as_str()), config)
1117            }
1118            ReflowMode::SentencePerLine => {
1119                let sentences = split_into_sentences(
1120                    &paragraph_text,
1121                    Some(&defined_references),
1122                    config.require_sentence_capital,
1123                );
1124                sentences.len() > 1 || line_data.len() > 1
1125            }
1126            ReflowMode::SemanticLineBreaks => {
1127                let sentences = split_into_sentences(
1128                    &paragraph_text,
1129                    Some(&defined_references),
1130                    config.require_sentence_capital,
1131                );
1132                sentences.len() > 1
1133                    || line_data.len() > 1
1134                    || collected
1135                        .iter()
1136                        .any(|l| self.calculate_effective_length(lines[l.line_idx]) > config.line_length.get())
1137            }
1138            ReflowMode::Default => collected
1139                .iter()
1140                .any(|l| self.calculate_effective_length(lines[l.line_idx]) > config.line_length.get()),
1141        };
1142
1143        if !needs_reflow {
1144            return (None, next_idx);
1145        }
1146
1147        let fallback_prefix = start_bq.prefix.clone();
1148        let explicit_prefix = dominant_blockquote_prefix(&line_data, &fallback_prefix);
1149        // Shift the whole quote right to track a widened parent list item's content
1150        // column (only widening matters for nesting; a narrowed parent leaves the quote
1151        // harmlessly over-indented, which MD027/MD030 tidy).
1152        let explicit_prefix = if ancestor_shift > 0 {
1153            format!("{}{explicit_prefix}", " ".repeat(ancestor_shift as usize))
1154        } else {
1155            explicit_prefix
1156        };
1157        let continuation_style = blockquote_continuation_style(&line_data);
1158
1159        let reflow_line_length = if config.line_length.is_unlimited() {
1160            usize::MAX
1161        } else {
1162            config
1163                .line_length
1164                .get()
1165                .saturating_sub(self.calculate_string_length(&explicit_prefix))
1166                .max(1)
1167        };
1168
1169        let reflow_options = Self::reflow_options(ctx, config, reflow_line_length);
1170
1171        let reflowed_with_style =
1172            reflow_blockquote_content(&line_data, &explicit_prefix, continuation_style, &reflow_options);
1173
1174        if reflowed_with_style.is_empty() {
1175            return (None, next_idx);
1176        }
1177
1178        let reflowed_text = reflowed_with_style.join(line_ending);
1179
1180        let start_range = ctx.whole_line_byte_range(paragraph_start + 1);
1181        let end_range = if end_line == lines.len() - 1 && !ctx.content.ends_with('\n') {
1182            ctx.line_text_byte_range(end_line + 1, 1, lines[end_line].len() + 1)
1183        } else {
1184            ctx.whole_line_byte_range(end_line + 1)
1185        };
1186        let byte_range = start_range.start..end_range.end;
1187
1188        let replacement = if end_line < lines.len() - 1 || ctx.content.ends_with('\n') {
1189            format!("{reflowed_text}{line_ending}")
1190        } else {
1191            reflowed_text
1192        };
1193
1194        let original_text = &ctx.content[byte_range.clone()];
1195        if original_text == replacement {
1196            return (None, next_idx);
1197        }
1198
1199        let (warning_line, warning_end_line) = match config.reflow_mode {
1200            ReflowMode::Normalize => (paragraph_start + 1, end_line + 1),
1201            ReflowMode::SentencePerLine | ReflowMode::SemanticLineBreaks => (paragraph_start + 1, end_line + 1),
1202            ReflowMode::Default => {
1203                let violating_line = collected
1204                    .iter()
1205                    .find(|line| self.calculate_effective_length(lines[line.line_idx]) > config.line_length.get())
1206                    .map_or(paragraph_start + 1, |line| line.line_idx + 1);
1207                (violating_line, violating_line)
1208            }
1209        };
1210
1211        let warning = LintWarning {
1212            rule_name: Some(self.name().to_string()),
1213            message: match config.reflow_mode {
1214                ReflowMode::Normalize => format!(
1215                    "Paragraph could be normalized to use line length of {} characters",
1216                    config.line_length.get()
1217                ),
1218                ReflowMode::SentencePerLine => {
1219                    let num_sentences = split_into_sentences(
1220                        &paragraph_text,
1221                        Some(&defined_references),
1222                        config.require_sentence_capital,
1223                    )
1224                    .len();
1225                    if line_data.len() == 1 {
1226                        format!("Line contains {num_sentences} sentences (one sentence per line required)")
1227                    } else {
1228                        let num_lines = line_data.len();
1229                        format!(
1230                            "Paragraph should have one sentence per line (found {num_sentences} sentences across {num_lines} lines)"
1231                        )
1232                    }
1233                }
1234                ReflowMode::SemanticLineBreaks => {
1235                    let num_sentences = split_into_sentences(
1236                        &paragraph_text,
1237                        Some(&defined_references),
1238                        config.require_sentence_capital,
1239                    )
1240                    .len();
1241                    format!("Paragraph should use semantic line breaks ({num_sentences} sentences)")
1242                }
1243                ReflowMode::Default => format!("Line length exceeds {} characters", config.line_length.get()),
1244            },
1245            line: warning_line,
1246            column: 1,
1247            end_line: warning_end_line,
1248            end_column: lines[warning_end_line.saturating_sub(1)].chars().count() + 1,
1249            severity: Severity::Warning,
1250            fix: Some(crate::rule::Fix::new(byte_range, replacement)),
1251        };
1252
1253        (Some(warning), next_idx)
1254    }
1255
1256    /// Reflow a single list item that lives inside a blockquote.
1257    ///
1258    /// The blockquote paragraph reflow treats a list marker as a content boundary,
1259    /// so `> - long item ...` is never wrapped even though the identical top-level
1260    /// item is. This handles that case: it collects one tight, prose-only list item
1261    /// at the starting blockquote level, reflows the item body to the configured
1262    /// width, and re-emits it with the blockquote prefix preserved and continuation
1263    /// lines aligned under the list content.
1264    ///
1265    /// Sibling and nested list items end collection and are reflowed independently
1266    /// by the caller's outer loop (a nested item carries its indent folded into the
1267    /// blockquote prefix, so it reflows correctly on its own). Items that are not
1268    /// simple tight prose - those embedding a code block, table, fence, or hard
1269    /// break - are left untouched (`None`) and the cursor still advances past the
1270    /// whole item so its inner lines are never reprocessed as loose prose.
1271    #[allow(clippy::too_many_arguments)]
1272    fn generate_blockquote_list_item_fix(
1273        &self,
1274        ctx: &crate::lint_context::LintContext,
1275        config: &MD013Config,
1276        lines: &[&str],
1277        start_idx: usize,
1278        line_ending: &str,
1279        // Extra indent (spaces) to prepend to the emitted `>` prefix when this quoted
1280        // list lives inside a list item whose marker widened. Zero unless a non-default
1281        // MD030 widened an ancestor list item.
1282        ancestor_shift: isize,
1283        // One entry per document line, true where a code span crosses one of the
1284        // line's boundaries. The caller reads them off one pass over the document
1285        // and shares them across every item, so an item costs no pass of its own.
1286        code_span_touches: &[bool],
1287    ) -> (Option<LintWarning>, usize) {
1288        use crate::utils::blockquote::effective_indent_in_blockquote;
1289
1290        let Some(start_bq) = ctx.lines.get(start_idx).and_then(|line| line.blockquote.as_deref()) else {
1291            return (None, start_idx + 1);
1292        };
1293
1294        let defined_references = Self::defined_reference_labels(ctx);
1295
1296        // A `>`-prefixed line can be marked as a blockquote even inside a fenced code
1297        // block (or other verbatim structure); such content must never be reflowed.
1298        if self.line_in_verbatim_context(start_idx + 1, ctx, config) {
1299            return (None, start_idx + 1);
1300        }
1301
1302        let target_level = start_bq.nesting_level;
1303
1304        // The marker line carries the canonical blockquote prefix: its content begins
1305        // with the list marker, so no list indent has been folded into the prefix.
1306        // Track a widened parent list item's content column so the quote stays nested
1307        // (only widening can detach it; narrowing just over-indents).
1308        let bq_prefix = if ancestor_shift > 0 {
1309            format!("{}{}", " ".repeat(ancestor_shift as usize), start_bq.prefix)
1310        } else {
1311            start_bq.prefix.clone()
1312        };
1313
1314        // A thematic break opens with what looks like a bullet marker (`- - -`).
1315        // It is not a list item, and reflowing it as prose destroys the break.
1316        // The top-level reflow path applies the same exemption.
1317        if is_horizontal_rule(&start_bq.content) {
1318            return (None, start_idx + 1);
1319        }
1320
1321        let (marker, first_body) = extract_list_marker_and_content(&start_bq.content);
1322        if marker.is_empty() {
1323            return (None, start_idx + 1);
1324        }
1325        let marker_width = marker.chars().count();
1326
1327        // Continuation lines of a checkbox item align under the bullet+checkbox, but
1328        // are recognized from the bullet width, matching the top-level list reflow.
1329        let base_marker_width = ["[ ] ", "[x] ", "[X] "]
1330            .iter()
1331            .find_map(|cb| marker.find(*cb))
1332            .unwrap_or(marker_width);
1333
1334        // Collect the item: the marker line plus its tight prose continuation lines.
1335        // `end_idx` always tracks the last consumed line so the cursor advances past
1336        // the entire item, even when it turns out to be too complex to reflow safely.
1337        let first_piece = trim_preserving_hard_break(&first_body);
1338        let mut simple = !has_hard_break(&first_piece);
1339        let mut body_pieces: Vec<String> = vec![first_piece];
1340        let mut end_idx = start_idx;
1341        let mut i = start_idx + 1;
1342
1343        while i < lines.len() {
1344            let Some(bq) = ctx.lines[i].blockquote.as_deref() else {
1345                // A blank line ends the item.
1346                if lines[i].trim().is_empty() {
1347                    break;
1348                }
1349                // A lazy continuation (no `>` marker) is too ambiguous to reflow
1350                // safely. Consume the whole lazy run into this item's span and leave
1351                // the item untouched, so the caller does not reflow the continuation
1352                // in isolation and leave the marker line partially fixed.
1353                simple = false;
1354                while i < lines.len() && ctx.lines[i].blockquote.is_none() && !lines[i].trim().is_empty() {
1355                    end_idx = i;
1356                    i += 1;
1357                }
1358                break;
1359            };
1360            if bq.nesting_level != target_level {
1361                break;
1362            }
1363
1364            let content = bq.content.as_str();
1365            if content.trim().is_empty() {
1366                // Blank quoted line ends the tight paragraph. A following indented
1367                // paragraph (loose item) is reflowed on its own by the prose path.
1368                break;
1369            }
1370
1371            let eff_indent = effective_indent_in_blockquote(lines[i], target_level, 0);
1372            if eff_indent < base_marker_width {
1373                // Dedented: a sibling list item or text outside this item. Stop here
1374                // and let the outer loop classify it.
1375                break;
1376            }
1377            if is_list_item(content) {
1378                // A nested list item: its own item, handled independently.
1379                break;
1380            }
1381
1382            // An embedded structure (code block, table, fence, nested quote, ...)
1383            // means the item is not simple prose: keep consuming so the cursor clears
1384            // the whole structure, but do not produce a fix.
1385            if self.is_blockquote_content_boundary(content, i + 1, ctx, config) {
1386                simple = false;
1387            }
1388
1389            let piece = trim_preserving_hard_break(content);
1390            if has_hard_break(&piece) {
1391                simple = false;
1392            }
1393            body_pieces.push(piece);
1394            end_idx = i;
1395            i += 1;
1396        }
1397
1398        let next_idx = end_idx + 1;
1399
1400        if !simple || holds_definition_list(ctx, start_idx, end_idx) {
1401            return (None, next_idx);
1402        }
1403
1404        let exceeds_limit =
1405            || (start_idx..=end_idx).any(|idx| self.calculate_effective_length(lines[idx]) > config.line_length.get());
1406        let body_text = body_pieces.join(" ");
1407        let body_text = body_text.trim();
1408
1409        // A body line that is one whole `$$...$$` expression renders as a display
1410        // block, so it holds a line of its own and the prose on either side of it
1411        // is reflowed separately. Each segment carries whether it is that line.
1412        // A line touched by a code span crossing one of its boundaries is code,
1413        // not such a block. The pieces are the consecutive lines from
1414        // `start_idx`, one piece each.
1415        let body_segments: Vec<(bool, Vec<&str>)> = {
1416            let mut segments: Vec<(bool, Vec<&str>)> = Vec::new();
1417            let mut current: Vec<&str> = Vec::new();
1418            for (offset, piece) in body_pieces.iter().enumerate() {
1419                if (is_self_contained_display_math_line(piece)
1420                    || self.line_is_standalone_bracket_math(start_idx + offset + 1, ctx, config))
1421                    && !line_touches_multiline_code_span(code_span_touches, start_idx + offset + 1)
1422                {
1423                    if !current.is_empty() {
1424                        segments.push((false, std::mem::take(&mut current)));
1425                    }
1426                    segments.push((true, vec![piece.trim_start()]));
1427                } else {
1428                    current.push(piece.as_str());
1429                }
1430            }
1431            if !current.is_empty() {
1432                segments.push((false, current));
1433            }
1434            segments
1435        };
1436        let holds_display_math = body_segments.iter().any(|(is_math, _)| *is_math);
1437
1438        // Some bodies cannot be shortened and must stay verbatim, matching the
1439        // exemptions the top-level list reflow applies: link reference definitions
1440        // always, and (in non-strict mode) standalone links/images and HTML-only
1441        // lines. Reflowing a link reference definition would split it after the
1442        // colon/URL and break the definition.
1443        let is_link_ref_def =
1444            body_text.starts_with('[') && body_text.contains("]:") && LINK_REF_PATTERN.is_match(body_text);
1445        let raw_marker_line = lines[start_idx];
1446        let body_is_unwrappable = is_link_ref_def
1447            || standalone_link_ends_paragraph(ctx, start_idx + 1, config)
1448            || (!config.strict && is_html_only_line(raw_marker_line));
1449        if body_is_unwrappable {
1450            return (None, next_idx);
1451        }
1452
1453        let needs_reflow = match config.reflow_mode {
1454            ReflowMode::Normalize => body_pieces.len() > 1 || exceeds_limit(),
1455            ReflowMode::Default => exceeds_limit(),
1456            ReflowMode::SentencePerLine => {
1457                split_into_sentences(body_text, Some(&defined_references), config.require_sentence_capital).len() > 1
1458                    || body_pieces.len() > 1
1459            }
1460            ReflowMode::SemanticLineBreaks => {
1461                split_into_sentences(body_text, Some(&defined_references), config.require_sentence_capital).len() > 1
1462                    || exceeds_limit()
1463            }
1464        };
1465        if !needs_reflow {
1466            return (None, next_idx);
1467        }
1468
1469        // Apply MD030 list-marker spacing in the spacing-normalizing modes, mirroring
1470        // the top-level list reflow: derive the post-marker spacing from MD030 and let
1471        // the continuation indent follow the resulting content width. Default MD030 (a
1472        // single space) leaves the marker unchanged. MkDocs keeps its rigid indent.
1473        let (marker, marker_width) = if matches!(config.reflow_mode, ReflowMode::Default | ReflowMode::Normalize)
1474            && !ctx.flavor.requires_strict_list_indent()
1475        {
1476            let is_ordered = marker.starts_with(|c: char| c.is_ascii_digit());
1477            // Bullet/number portion only (e.g. `-`, `1.`); the checkbox is content.
1478            let bullet = marker.split(' ').next().unwrap_or("");
1479            let bullet_len = bullet.chars().count();
1480            let checkbox_tail = &marker[base_marker_width..];
1481            // Decide single- vs multi-line spacing from the rewritten shape. This path
1482            // only handles a single tight prose paragraph (structural or multi-paragraph
1483            // items set `simple = false` and bail out above), so the emitted item stays
1484            // multi-line solely when the joined body wraps past one line. A multi-line
1485            // *source* that collapses onto the marker line must use MD030's single-line
1486            // spacing, matching the top-level reflow. The wrap test measures at the
1487            // single-line content column so it does not depend on the spacing chosen here.
1488            let single_col = self.calculate_string_length(&bq_prefix)
1489                + bullet_len
1490                + self.list_spacing.expected_spaces(is_ordered, false, bullet_len)
1491                + checkbox_tail.chars().count();
1492            // A display-math line always holds a line of its own, so an item that
1493            // carries one spans several lines whatever the joined body measures.
1494            let is_multi = holds_display_math
1495                || (!body_text.is_empty()
1496                    && self.calculate_effective_length(&format!("{}{body_text}", " ".repeat(single_col)))
1497                        > config.line_length.effective_limit());
1498            let spaces = self.list_spacing.expected_spaces(is_ordered, is_multi, bullet_len);
1499            let new_marker = format!("{bullet}{}{checkbox_tail}", " ".repeat(spaces));
1500            let width = new_marker.chars().count();
1501            (new_marker, width)
1502        } else {
1503            (marker, marker_width)
1504        };
1505
1506        let prefix_width = self.calculate_string_length(&bq_prefix) + self.calculate_string_length(&marker);
1507        let reflow_line_length = if config.line_length.is_unlimited() {
1508            usize::MAX
1509        } else {
1510            config.line_length.get().saturating_sub(prefix_width).max(1)
1511        };
1512
1513        let reflow_options = Self::reflow_options(ctx, config, reflow_line_length);
1514
1515        // A display-math segment is emitted as written; a prose segment is joined
1516        // and reflowed on its own, so the prose above and below the expression
1517        // wraps within its own paragraph.
1518        let mut reflowed: Vec<String> = Vec::new();
1519        for (is_math, segment) in &body_segments {
1520            if *is_math {
1521                reflowed.push(segment[0].to_string());
1522                continue;
1523            }
1524            let segment_text = segment.join(" ");
1525            let segment_text = segment_text.trim();
1526            if segment_text.is_empty() {
1527                continue;
1528            }
1529            reflowed.extend(crate::utils::text_reflow::reflow_line(segment_text, &reflow_options));
1530        }
1531        if reflowed.is_empty() {
1532            return (None, next_idx);
1533        }
1534
1535        let continuation_indent = " ".repeat(marker_width);
1536        let reflowed_text = reflowed
1537            .iter()
1538            .enumerate()
1539            .map(|(idx, line)| {
1540                if idx == 0 {
1541                    format!("{bq_prefix}{marker}{line}")
1542                } else {
1543                    format!("{bq_prefix}{continuation_indent}{line}")
1544                }
1545            })
1546            .collect::<Vec<_>>()
1547            .join(line_ending);
1548
1549        let start_range = ctx.whole_line_byte_range(start_idx + 1);
1550        let end_range = if end_idx == lines.len() - 1 && !ctx.content.ends_with('\n') {
1551            ctx.line_text_byte_range(end_idx + 1, 1, lines[end_idx].len() + 1)
1552        } else {
1553            ctx.whole_line_byte_range(end_idx + 1)
1554        };
1555        let byte_range = start_range.start..end_range.end;
1556
1557        let replacement = if end_idx < lines.len() - 1 || ctx.content.ends_with('\n') {
1558            format!("{reflowed_text}{line_ending}")
1559        } else {
1560            reflowed_text
1561        };
1562
1563        let original_text = &ctx.content[byte_range.clone()];
1564        if original_text == replacement {
1565            return (None, next_idx);
1566        }
1567
1568        let message = match config.reflow_mode {
1569            ReflowMode::Normalize => format!(
1570                "Paragraph could be normalized to use line length of {} characters",
1571                config.line_length.get()
1572            ),
1573            ReflowMode::SentencePerLine => {
1574                let num_sentences =
1575                    split_into_sentences(body_text, Some(&defined_references), config.require_sentence_capital).len();
1576                format!("List item should have one sentence per line (found {num_sentences} sentences)")
1577            }
1578            ReflowMode::SemanticLineBreaks => {
1579                let num_sentences =
1580                    split_into_sentences(body_text, Some(&defined_references), config.require_sentence_capital).len();
1581                format!("List item should use semantic line breaks ({num_sentences} sentences)")
1582            }
1583            ReflowMode::Default => format!("Line length exceeds {} characters", config.line_length.get()),
1584        };
1585
1586        let warning = LintWarning {
1587            rule_name: Some(self.name().to_string()),
1588            message,
1589            line: start_idx + 1,
1590            column: 1,
1591            end_line: end_idx + 1,
1592            end_column: lines[end_idx].chars().count() + 1,
1593            severity: Severity::Warning,
1594            fix: Some(crate::rule::Fix::new(byte_range, replacement)),
1595        };
1596
1597        (Some(warning), next_idx)
1598    }
1599
1600    /// Generate paragraph-based fixes
1601    fn generate_paragraph_fixes(
1602        &self,
1603        ctx: &crate::lint_context::LintContext,
1604        config: &MD013Config,
1605        lines: &[&str],
1606    ) -> Vec<LintWarning> {
1607        let mut warnings = Vec::new();
1608        let defined_references = Self::defined_reference_labels(ctx);
1609        // A line touched by a code span crossing one of its boundaries is code
1610        // however it is spelled, so a `$$...$$` expression on one is no display
1611        // block.
1612        let code_span_touches = crate::utils::text_reflow::lines_touching_multiline_code_span(ctx.content);
1613
1614        // Detect the content's line ending style to preserve it in replacements.
1615        // The LSP receives content from editors which may use CRLF (Windows).
1616        // Replacements must match the original line endings to avoid false positives.
1617        let line_ending = crate::utils::line_ending::detect_line_ending(ctx.content);
1618
1619        // Ancestor list-item indent shifts, innermost last. When a reflowed parent's
1620        // marker widens under a non-default MD030 (e.g. ul-multi = 3 moves the parent's
1621        // content from column 2 to 4), its nested list/blockquote children are reflowed
1622        // independently and would otherwise keep their original indent — leaving them
1623        // under the parent's new content column, where a CommonMark parser reparses them
1624        // as siblings rather than children. Each frame is (normalized marker width,
1625        // cumulative shift applied to that item's content column); a descendant adds its
1626        // innermost open ancestor's shift to its own indent so the whole subtree moves
1627        // together. With a default MD030 and no marker padding every shift is 0, so this
1628        // is inert and the output is byte-identical.
1629        let mut list_shift_stack: Vec<(usize, isize)> = Vec::new();
1630
1631        let mut i = 0;
1632        while i < lines.len() {
1633            let line_num = i + 1;
1634
1635            // Close ancestor frames whose list item has ended at this line: a non-blank
1636            // line indented less than the frame's source content column is no longer
1637            // inside that item. Blank lines alone don't close a (loose) list item.
1638            if !list_shift_stack.is_empty()
1639                && let Some(info) = ctx.lines.get(i)
1640                && !info.is_blank
1641            {
1642                while let Some(&(content_column, _)) = list_shift_stack.last() {
1643                    if info.indent < content_column {
1644                        list_shift_stack.pop();
1645                    } else {
1646                        break;
1647                    }
1648                }
1649            }
1650
1651            // Handle blockquote paragraphs with style-preserving reflow.
1652            // Skip blockquotes when blockquotes=false or paragraphs=false
1653            if line_num > 0 && line_num <= ctx.lines.len() && ctx.lines[line_num - 1].blockquote.is_some() {
1654                if !config.blockquotes || !config.paragraphs {
1655                    // Skip past all blockquote lines (explicit and lazy continuations).
1656                    // A lazy continuation is a non-blank line without `>` that follows
1657                    // a blockquote line and isn't a structural element.
1658                    let mut saw_explicit_bq = false;
1659                    while i < lines.len() && i < ctx.lines.len() {
1660                        if ctx.lines[i].blockquote.is_some() {
1661                            saw_explicit_bq = true;
1662                            i += 1;
1663                        } else if saw_explicit_bq
1664                            && !lines[i].trim().is_empty()
1665                            && !lines[i].trim_start().starts_with('#')
1666                            && !lines[i].trim_start().starts_with('>')
1667                        {
1668                            // Lazy continuation of preceding blockquote
1669                            i += 1;
1670                        } else {
1671                            break;
1672                        }
1673                    }
1674                    continue;
1675                }
1676                // A blockquote nested in a list item moves with its parent when the
1677                // parent's marker widens (see `list_shift_stack`); pass that shift so the
1678                // emitted `>` prefix lands under the parent's new content column instead
1679                // of detaching into a sibling.
1680                let ancestor_shift = list_shift_stack.last().map_or(0isize, |&(_, shift)| shift);
1681                // A list item inside the blockquote needs list-aware reflow (marker +
1682                // continuation indent); plain prose goes through the paragraph path.
1683                let is_bq_list_item = ctx.lines[i]
1684                    .blockquote
1685                    .as_deref()
1686                    .is_some_and(|bq| is_list_item(&bq.content));
1687                let (warning, next_idx) = if is_bq_list_item {
1688                    self.generate_blockquote_list_item_fix(
1689                        ctx,
1690                        config,
1691                        lines,
1692                        i,
1693                        line_ending,
1694                        ancestor_shift,
1695                        &code_span_touches,
1696                    )
1697                } else {
1698                    self.generate_blockquote_paragraph_fix(ctx, config, lines, i, line_ending, ancestor_shift)
1699                };
1700                if let Some(warning) = warning {
1701                    warnings.push(warning);
1702                }
1703                i = next_idx;
1704                continue;
1705            }
1706
1707            // Skip special structures (but NOT MkDocs containers - those get special handling)
1708            let should_skip_due_to_line_info = ctx.line_info(line_num).is_some_and(|info| {
1709                info.in_code_block
1710                    || info.in_front_matter
1711                    || info.in_html_block
1712                    || info.in_html_comment
1713                    || info.in_esm_block
1714                    || info.in_jsx_expression
1715                    || info.in_jsx_block
1716                    || info.in_mdx_comment
1717                    || info.in_mkdocstrings
1718                    || info.in_pymdown_block
1719            });
1720
1721            // Skip link reference definitions but NOT footnote definitions.
1722            // Footnote definitions (`[^id]: prose`) contain reflowable text,
1723            // while link reference definitions (`[ref]: URL`) contain URLs
1724            // that cannot be shortened.
1725            let is_link_ref_def =
1726                lines[i].trim().starts_with('[') && !lines[i].trim().starts_with("[^") && lines[i].contains("]:");
1727
1728            // A setext heading is a heading, not a paragraph: skip every line of
1729            // its text and its underline together, the way an ATX heading is
1730            // skipped just below. Reflowing any part rewrites the document's
1731            // structure - joining the underline onto the text demotes the
1732            // heading to prose, and rewrapping the text moves words across the
1733            // heading boundary. The text spans the whole paragraph the underline
1734            // ends, so walk the flag to the end of it; the line after the last
1735            // text line is the underline.
1736            if is_setext_heading_text_line(ctx, line_num) {
1737                while i < lines.len() && is_setext_heading_text_line(ctx, i + 1) {
1738                    i += 1;
1739                }
1740                i += 1;
1741                continue;
1742            }
1743
1744            if should_skip_due_to_line_info
1745                || lines[i].trim().starts_with('#')
1746                || TableUtils::is_potential_table_row_with_flavor(lines[i], ctx.flavor)
1747                || lines[i].trim().is_empty()
1748                || is_horizontal_rule(lines[i])
1749                || is_template_directive_only(lines[i])
1750                || is_link_ref_def
1751                || ctx.line_info(line_num).is_some_and(|info| info.is_div_marker)
1752                || is_html_only_line(lines[i])
1753                || standalone_link_ends_paragraph(ctx, line_num, config)
1754            {
1755                i += 1;
1756                continue;
1757            }
1758
1759            // Handle footnote definitions: `[^id]: prose text that can be reflowed`
1760            // Supports multi-paragraph footnotes with code blocks, blockquotes,
1761            // tables, and lists preserved verbatim.
1762            // Validate structure: must start with `[^`, contain `]:`, and the ID
1763            // must not contain `[` or `]` (prevents false matches on nested brackets)
1764            if lines[i].trim().starts_with("[^") && lines[i].contains("]:") && {
1765                let after_caret = &lines[i].trim()[2..];
1766                after_caret
1767                    .find("]:")
1768                    .is_some_and(|pos| pos > 0 && !after_caret[..pos].contains(['[', ']']))
1769            } {
1770                let footnote_start = i;
1771                let line = lines[i];
1772
1773                // Extract the prefix `[^id]:`
1774                let Some(colon_pos) = line.find("]:") else {
1775                    i += 1;
1776                    continue;
1777                };
1778                let prefix_end = colon_pos + 2;
1779                let prefix = &line[..prefix_end];
1780
1781                // Content starts after `]: ` (with optional space)
1782                let content_start = if line[prefix_end..].starts_with(' ') {
1783                    prefix_end + 1
1784                } else {
1785                    prefix_end
1786                };
1787                let first_content = &line[content_start..];
1788
1789                // CommonMark footnotes use 4-space continuation indent
1790                const FN_INDENT: usize = 4;
1791
1792                // --- Line classification for footnote content ---
1793                #[derive(Debug, Clone)]
1794                enum FnLineType {
1795                    Content(String),
1796                    Verbatim(String, usize), // preserved text, original indent
1797                    Empty,
1798                }
1799
1800                // Helper: compute visual indent (tabs = 4 spaces)
1801                let visual_indent = |s: &str| -> usize {
1802                    s.chars()
1803                        .take_while(|c| c.is_whitespace())
1804                        .map(|c| if c == '\t' { 4 } else { 1 })
1805                        .sum::<usize>()
1806                };
1807
1808                // Helper: check if a trimmed line is a fence marker (homogeneous chars)
1809                let is_fence = |s: &str| -> bool {
1810                    let t = s.trim();
1811                    let fence_char = t.chars().next();
1812                    matches!(fence_char, Some('`') | Some('~'))
1813                        && t.chars().take_while(|&c| c == fence_char.unwrap()).count() >= 3
1814                };
1815
1816                // Helper: check if a trimmed line is a setext underline
1817                let is_setext_underline = |s: &str| -> bool {
1818                    let t = s.trim();
1819                    !t.is_empty()
1820                        && (t.chars().all(|c| c == '=' || c == ' ') || t.chars().all(|c| c == '-' || c == ' '))
1821                        && t.contains(['=', '-'])
1822                };
1823
1824                // Deferred body: `[^id]:\n    content` — first line has no content,
1825                // actual content starts on the next indented line
1826                let deferred_body = first_content.trim().is_empty();
1827
1828                // Collect all lines belonging to this footnote definition
1829                let mut fn_lines: Vec<FnLineType> = Vec::new();
1830                if !deferred_body {
1831                    fn_lines.push(FnLineType::Content(first_content.to_string()));
1832                }
1833                let mut last_consumed = i;
1834                i += 1;
1835
1836                // Strip only the footnote continuation indent, preserving
1837                // internal indentation (e.g., code block body indent)
1838                let strip_fn_indent = |s: &str| -> String {
1839                    let mut chars = s.chars();
1840                    let mut stripped = 0;
1841                    while stripped < FN_INDENT {
1842                        match chars.next() {
1843                            Some('\t') => stripped += 4,
1844                            Some(c) if c.is_whitespace() => stripped += 1,
1845                            _ => break,
1846                        }
1847                    }
1848                    chars.as_str().to_string()
1849                };
1850
1851                let mut in_fenced_code = false;
1852                let mut consecutive_blanks = 0u32;
1853
1854                while i < lines.len() {
1855                    let next = lines[i];
1856                    let next_trimmed = next.trim();
1857
1858                    // Blank line handling
1859                    if next_trimmed.is_empty() {
1860                        consecutive_blanks += 1;
1861                        // 2+ consecutive blanks terminate the footnote
1862                        if consecutive_blanks >= 2 {
1863                            break;
1864                        }
1865
1866                        // Inside a fenced code block, blank lines are part of the code
1867                        if in_fenced_code {
1868                            consecutive_blanks = 0; // Don't count blanks inside code blocks
1869                            fn_lines.push(FnLineType::Verbatim(String::new(), 0));
1870                            last_consumed = i;
1871                            i += 1;
1872                            continue;
1873                        }
1874
1875                        // Peek ahead: if next non-blank line is indented >= FN_INDENT,
1876                        // this blank is an internal paragraph separator
1877                        if i + 1 < lines.len() {
1878                            let peek = lines[i + 1];
1879                            let peek_indent = visual_indent(peek);
1880                            if !peek.trim().is_empty() && peek_indent >= FN_INDENT {
1881                                fn_lines.push(FnLineType::Empty);
1882                                last_consumed = i;
1883                                i += 1;
1884                                continue;
1885                            }
1886                        }
1887                        // No valid continuation after blank — end of footnote
1888                        break;
1889                    }
1890
1891                    consecutive_blanks = 0;
1892                    let indent = visual_indent(next);
1893
1894                    // Not indented enough — end of footnote
1895                    if indent < FN_INDENT {
1896                        break;
1897                    }
1898
1899                    // Inside a fenced code block: everything is verbatim until closing fence
1900                    if in_fenced_code {
1901                        fn_lines.push(FnLineType::Verbatim(strip_fn_indent(next), indent));
1902                        if is_fence(next_trimmed) {
1903                            in_fenced_code = false;
1904                        }
1905                        last_consumed = i;
1906                        i += 1;
1907                        continue;
1908                    }
1909
1910                    // Fence opener — start verbatim code block
1911                    if is_fence(next_trimmed) {
1912                        in_fenced_code = true;
1913                        fn_lines.push(FnLineType::Verbatim(strip_fn_indent(next), indent));
1914                        last_consumed = i;
1915                        i += 1;
1916                        continue;
1917                    }
1918
1919                    // A multi-line display-math block is verbatim: its line breaks
1920                    // carry meaning (see `line_in_multiline_math_block`).
1921                    if self.line_in_multiline_math_block(i + 1, ctx, config) {
1922                        fn_lines.push(FnLineType::Verbatim(strip_fn_indent(next), indent));
1923                        last_consumed = i;
1924                        i += 1;
1925                        continue;
1926                    }
1927
1928                    // Indented code block: indent >= FN_INDENT + 4 (= 8 spaces)
1929                    if indent >= FN_INDENT + 4 {
1930                        fn_lines.push(FnLineType::Verbatim(strip_fn_indent(next), indent));
1931                        last_consumed = i;
1932                        i += 1;
1933                        continue;
1934                    }
1935
1936                    // Structural content that must be preserved verbatim
1937                    if next_trimmed.starts_with('#')
1938                        || is_list_item(next_trimmed)
1939                        || next_trimmed.starts_with('>')
1940                        || TableUtils::is_potential_table_row_with_flavor(next_trimmed, ctx.flavor)
1941                        || is_setext_underline(next_trimmed)
1942                        || is_horizontal_rule(next_trimmed)
1943                        || crate::utils::mkdocs_footnotes::is_footnote_definition(next_trimmed)
1944                    {
1945                        // Preserve verbatim: blockquotes, tables, lists, setext
1946                        // underlines, and horizontal rules inside the footnote
1947                        if next_trimmed.starts_with('>')
1948                            || TableUtils::is_potential_table_row_with_flavor(next_trimmed, ctx.flavor)
1949                            || is_list_item(next_trimmed)
1950                            || is_setext_underline(next_trimmed)
1951                            || is_horizontal_rule(next_trimmed)
1952                        {
1953                            fn_lines.push(FnLineType::Verbatim(strip_fn_indent(next), indent));
1954                            last_consumed = i;
1955                            i += 1;
1956                            continue;
1957                        }
1958                        // Headings, new footnote defs, link refs — end the footnote
1959                        break;
1960                    }
1961
1962                    // Link reference definitions inside footnotes are not reflowable
1963                    if next_trimmed.starts_with('[')
1964                        && !next_trimmed.starts_with("[^")
1965                        && next_trimmed.contains("]:")
1966                        && LINK_REF_PATTERN.is_match(next_trimmed)
1967                    {
1968                        fn_lines.push(FnLineType::Verbatim(strip_fn_indent(next), indent));
1969                        last_consumed = i;
1970                        i += 1;
1971                        continue;
1972                    }
1973
1974                    // HTML-only lines inside footnotes are not reflowable
1975                    if is_html_only_line(next_trimmed) {
1976                        fn_lines.push(FnLineType::Verbatim(strip_fn_indent(next), indent));
1977                        last_consumed = i;
1978                        i += 1;
1979                        continue;
1980                    }
1981
1982                    // Regular prose content
1983                    fn_lines.push(FnLineType::Content(next_trimmed.to_string()));
1984                    last_consumed = i;
1985                    i += 1;
1986                }
1987
1988                // Nothing collected or only empty lines
1989                if fn_lines.iter().all(|l| matches!(l, FnLineType::Empty)) || fn_lines.is_empty() {
1990                    continue;
1991                }
1992
1993                // The footnote is rebuilt with a fixed indent and its paragraphs
1994                // joined, which a definition list inside it does not survive.
1995                if holds_definition_list(ctx, footnote_start, last_consumed) {
1996                    continue;
1997                }
1998
1999                // --- Group into blocks ---
2000                #[derive(Debug)]
2001                enum FnBlock {
2002                    Paragraph(Vec<String>),
2003                    Verbatim(Vec<(String, usize)>), // (content, indent) preserved as-is
2004                }
2005
2006                let mut blocks: Vec<FnBlock> = Vec::new();
2007                let mut current_para: Vec<String> = Vec::new();
2008                let mut current_verbatim: Vec<(String, usize)> = Vec::new();
2009
2010                for fl in &fn_lines {
2011                    match fl {
2012                        FnLineType::Content(s) => {
2013                            if !current_verbatim.is_empty() {
2014                                blocks.push(FnBlock::Verbatim(std::mem::take(&mut current_verbatim)));
2015                            }
2016                            current_para.push(s.clone());
2017                        }
2018                        FnLineType::Verbatim(s, indent) => {
2019                            if !current_para.is_empty() {
2020                                blocks.push(FnBlock::Paragraph(std::mem::take(&mut current_para)));
2021                            }
2022                            current_verbatim.push((s.clone(), *indent));
2023                        }
2024                        FnLineType::Empty => {
2025                            if !current_para.is_empty() {
2026                                blocks.push(FnBlock::Paragraph(std::mem::take(&mut current_para)));
2027                            }
2028                            if !current_verbatim.is_empty() {
2029                                blocks.push(FnBlock::Verbatim(std::mem::take(&mut current_verbatim)));
2030                            }
2031                        }
2032                    }
2033                }
2034                if !current_para.is_empty() {
2035                    blocks.push(FnBlock::Paragraph(current_para));
2036                }
2037                if !current_verbatim.is_empty() {
2038                    blocks.push(FnBlock::Verbatim(current_verbatim));
2039                }
2040
2041                // --- Reflow paragraphs and reconstruct ---
2042                let prefix_display_width = prefix.chars().count() + 1; // +1 for space
2043                let reflow_line_length = if config.line_length.is_unlimited() {
2044                    usize::MAX
2045                } else {
2046                    config
2047                        .line_length
2048                        .get()
2049                        .saturating_sub(FN_INDENT.max(prefix_display_width))
2050                        .max(20)
2051                };
2052                // Footnote continuation uses a fixed 4-space indent, so list
2053                // continuation capping does not apply here.
2054                let reflow_options = crate::utils::text_reflow::ReflowOptions {
2055                    max_list_continuation_indent: None,
2056                    ..Self::reflow_options(ctx, config, reflow_line_length)
2057                };
2058
2059                let indent_str = " ".repeat(FN_INDENT);
2060                let mut result_lines: Vec<String> = Vec::new();
2061                let mut is_first_block = true;
2062
2063                for block in &blocks {
2064                    match block {
2065                        FnBlock::Paragraph(para_lines) => {
2066                            let paragraph_text = para_lines.join(" ");
2067                            let paragraph_text = paragraph_text.trim();
2068                            if paragraph_text.is_empty() {
2069                                continue;
2070                            }
2071
2072                            let reflowed = crate::utils::text_reflow::reflow_line(paragraph_text, &reflow_options);
2073                            if reflowed.is_empty() {
2074                                continue;
2075                            }
2076
2077                            // Blank line separator between blocks
2078                            if !result_lines.is_empty() {
2079                                result_lines.push(String::new());
2080                            }
2081
2082                            for (idx, rline) in reflowed.iter().enumerate() {
2083                                if is_first_block && idx == 0 {
2084                                    result_lines.push(format!("{prefix} {rline}"));
2085                                } else {
2086                                    result_lines.push(format!("{indent_str}{rline}"));
2087                                }
2088                            }
2089                            is_first_block = false;
2090                        }
2091                        FnBlock::Verbatim(verb_lines) => {
2092                            // Blank line separator between blocks
2093                            if !result_lines.is_empty() {
2094                                result_lines.push(String::new());
2095                            }
2096
2097                            if is_first_block {
2098                                // Verbatim as first block in a deferred-body footnote
2099                                if deferred_body {
2100                                    result_lines.push(prefix.to_string());
2101                                }
2102                                is_first_block = false;
2103                            }
2104                            for (content, _orig_indent) in verb_lines {
2105                                result_lines.push(format!("{indent_str}{content}"));
2106                            }
2107                        }
2108                    }
2109                }
2110
2111                // If nothing was produced, skip
2112                if result_lines.is_empty() {
2113                    continue;
2114                }
2115
2116                let reflowed_text = result_lines.join(line_ending);
2117
2118                // Calculate byte range using last_consumed
2119                let start_range = ctx.whole_line_byte_range(footnote_start + 1);
2120                let end_range = if last_consumed == lines.len() - 1 && !ctx.content.ends_with('\n') {
2121                    ctx.line_text_byte_range(last_consumed + 1, 1, lines[last_consumed].len() + 1)
2122                } else {
2123                    ctx.whole_line_byte_range(last_consumed + 1)
2124                };
2125                let byte_range = start_range.start..end_range.end;
2126
2127                let replacement = if last_consumed < lines.len() - 1 || ctx.content.ends_with('\n') {
2128                    format!("{reflowed_text}{line_ending}")
2129                } else {
2130                    reflowed_text
2131                };
2132
2133                let original_text = &ctx.content[byte_range.clone()];
2134                let max_length = (footnote_start..=last_consumed)
2135                    .map(|idx| self.calculate_effective_length(lines[idx]))
2136                    .max()
2137                    .unwrap_or(0);
2138                let line_limit = if config.line_length.is_unlimited() {
2139                    usize::MAX
2140                } else {
2141                    config.line_length.get()
2142                };
2143                if original_text != replacement && max_length > line_limit {
2144                    warnings.push(LintWarning {
2145                        rule_name: Some(self.name().to_string()),
2146                        message: format!(
2147                            "Line length {} exceeds {} characters",
2148                            max_length,
2149                            config.line_length.get()
2150                        ),
2151                        line: footnote_start + 1,
2152                        column: 1,
2153                        end_line: last_consumed + 1,
2154                        end_column: lines[last_consumed].chars().count() + 1,
2155                        severity: Severity::Warning,
2156                        fix: Some(crate::rule::Fix::new(byte_range, replacement)),
2157                    });
2158                }
2159                continue;
2160            }
2161
2162            // Handle MkDocs container content (admonitions and tabs) with indent-preserving reflow
2163            if ctx
2164                .line_info(line_num)
2165                .is_some_and(super::super::lint_context::types::LineInfo::in_mkdocs_container)
2166            {
2167                // Skip admonition/tab marker lines — only reflow their indented content
2168                let current_line = lines[i];
2169                if mkdocs_admonitions::is_admonition_start(current_line) || mkdocs_tabs::is_tab_marker(current_line) {
2170                    i += 1;
2171                    continue;
2172                }
2173
2174                let container_start = i;
2175
2176                // Detect the actual indent level from the first content line
2177                // (supports nested admonitions with 8+ spaces)
2178                let first_line = lines[i];
2179                let base_indent_len = first_line.len() - first_line.trim_start().len();
2180                let base_indent: String = " ".repeat(base_indent_len);
2181
2182                // Collect consecutive MkDocs container paragraph lines
2183                let mut container_lines: Vec<&str> = Vec::new();
2184                while i < lines.len() {
2185                    let current_line_num = i + 1;
2186                    let line_info = ctx.line_info(current_line_num);
2187
2188                    // Stop if we leave the MkDocs container
2189                    if !line_info.is_some_and(super::super::lint_context::types::LineInfo::in_mkdocs_container) {
2190                        break;
2191                    }
2192
2193                    let line = lines[i];
2194
2195                    // Stop at paragraph boundaries within the container
2196                    if line.trim().is_empty() {
2197                        break;
2198                    }
2199
2200                    // Skip list items, code blocks, headings, HTML-only lines within containers
2201                    if is_list_item(line.trim())
2202                        || line.trim().starts_with("```")
2203                        || line.trim().starts_with("~~~")
2204                        || line.trim().starts_with('#')
2205                        || is_html_only_line(line)
2206                    {
2207                        break;
2208                    }
2209
2210                    container_lines.push(line);
2211                    i += 1;
2212                }
2213
2214                if container_lines.is_empty() {
2215                    // Must advance i to avoid infinite loop when we encounter
2216                    // non-paragraph content (code block, list, heading, empty line)
2217                    // at the start of an MkDocs container
2218                    i += 1;
2219                    continue;
2220                }
2221
2222                // Strip the base indent from each line and join for reflow
2223                let stripped_lines: Vec<&str> = container_lines
2224                    .iter()
2225                    .map(|line| {
2226                        if line.starts_with(&base_indent) {
2227                            &line[base_indent_len..]
2228                        } else {
2229                            line.trim_start()
2230                        }
2231                    })
2232                    .collect();
2233                let paragraph_text = stripped_lines.join(" ");
2234
2235                // Check if reflow is needed
2236                let needs_reflow = match config.reflow_mode {
2237                    ReflowMode::Normalize => self.normalize_mode_needs_reflow(container_lines.iter().copied(), config),
2238                    ReflowMode::SentencePerLine => {
2239                        let sentences = split_into_sentences(
2240                            &paragraph_text,
2241                            Some(&defined_references),
2242                            config.require_sentence_capital,
2243                        );
2244                        sentences.len() > 1 || container_lines.len() > 1
2245                    }
2246                    ReflowMode::SemanticLineBreaks => {
2247                        let sentences = split_into_sentences(
2248                            &paragraph_text,
2249                            Some(&defined_references),
2250                            config.require_sentence_capital,
2251                        );
2252                        sentences.len() > 1
2253                            || container_lines.len() > 1
2254                            || container_lines
2255                                .iter()
2256                                .any(|line| self.calculate_effective_length(line) > config.line_length.get())
2257                    }
2258                    ReflowMode::Default => container_lines
2259                        .iter()
2260                        .any(|line| self.calculate_effective_length(line) > config.line_length.get()),
2261                };
2262
2263                if !needs_reflow {
2264                    continue;
2265                }
2266
2267                // Calculate byte range for this container paragraph
2268                let start_range = ctx.whole_line_byte_range(container_start + 1);
2269                let end_line = container_start + container_lines.len() - 1;
2270                let end_range = if end_line == lines.len() - 1 && !ctx.content.ends_with('\n') {
2271                    ctx.line_text_byte_range(end_line + 1, 1, lines[end_line].len() + 1)
2272                } else {
2273                    ctx.whole_line_byte_range(end_line + 1)
2274                };
2275                let byte_range = start_range.start..end_range.end;
2276
2277                // Reflow with adjusted line length (accounting for the 4-space indent)
2278                let reflow_line_length = if config.line_length.is_unlimited() {
2279                    usize::MAX
2280                } else {
2281                    config.line_length.get().saturating_sub(base_indent_len).max(1)
2282                };
2283                let reflow_options = Self::reflow_options(ctx, config, reflow_line_length);
2284                let reflowed = crate::utils::text_reflow::reflow_line(&paragraph_text, &reflow_options);
2285
2286                // Re-add the 4-space indent to each reflowed line
2287                let reflowed_with_indent: Vec<String> =
2288                    reflowed.iter().map(|line| format!("{base_indent}{line}")).collect();
2289                let reflowed_text = reflowed_with_indent.join(line_ending);
2290
2291                // Preserve trailing newline
2292                let replacement = if end_line < lines.len() - 1 || ctx.content.ends_with('\n') {
2293                    format!("{reflowed_text}{line_ending}")
2294                } else {
2295                    reflowed_text
2296                };
2297
2298                // Only generate a warning if the replacement is different
2299                let original_text = &ctx.content[byte_range.clone()];
2300                if original_text != replacement {
2301                    warnings.push(LintWarning {
2302                        rule_name: Some(self.name().to_string()),
2303                        message: format!(
2304                            "Line length {} exceeds {} characters (in MkDocs container)",
2305                            container_lines.iter().map(|l| l.len()).max().unwrap_or(0),
2306                            config.line_length.get()
2307                        ),
2308                        line: container_start + 1,
2309                        column: 1,
2310                        end_line: end_line + 1,
2311                        end_column: lines[end_line].chars().count() + 1,
2312                        severity: Severity::Warning,
2313                        fix: Some(crate::rule::Fix::new(byte_range, replacement)),
2314                    });
2315                }
2316                continue;
2317            }
2318
2319            // Helper function to detect semantic line markers
2320            let is_semantic_line = |content: &str| -> bool {
2321                let trimmed = content.trim_start();
2322                let semantic_markers = [
2323                    "NOTE:",
2324                    "WARNING:",
2325                    "IMPORTANT:",
2326                    "CAUTION:",
2327                    "TIP:",
2328                    "DANGER:",
2329                    "HINT:",
2330                    "INFO:",
2331                ];
2332                semantic_markers.iter().any(|marker| trimmed.starts_with(marker))
2333            };
2334
2335            // Helper function to detect fence markers (opening or closing)
2336            let is_fence_marker = |content: &str| -> bool {
2337                let trimmed = content.trim_start();
2338                trimmed.starts_with("```") || trimmed.starts_with("~~~")
2339            };
2340
2341            // Check if this is a list item - handle it specially
2342            let trimmed = lines[i].trim();
2343            if is_list_item(trimmed) {
2344                // Collect the entire list item including continuation lines
2345                let list_start = i;
2346                let (marker, first_content) = extract_list_marker_and_content(lines[i]);
2347                let marker_len = marker.len();
2348                // The normalized marker above is what gets re-emitted; the source marker
2349                // is where the item's content actually starts. Nested blocks move by the
2350                // difference between the two content columns, so the shift must be
2351                // measured against the source, not against the normalized width.
2352                let source_marker = source_list_marker(lines[i]);
2353                let source_content_col = source_marker.as_ref().map_or(marker_len, |m| m.content_col);
2354
2355                // Checkbox ([ ]/[x]/[X]) is inline content, not part of the list marker.
2356                // Use the base bullet/number marker width for continuation recognition
2357                // so that continuation lines at 2+ spaces are collected for "- [ ] " items.
2358                let base_marker_len = if marker.contains("[ ] ") || marker.contains("[x] ") || marker.contains("[X] ") {
2359                    marker.find('[').unwrap_or(marker_len)
2360                } else {
2361                    marker_len
2362                };
2363
2364                // MkDocs flavor requires at least 4 spaces for list continuation
2365                // after a blank line (multi-paragraph list items). For non-blank
2366                // continuation (lines directly following the marker line), use
2367                // the natural marker width so that 2-space indent is recognized.
2368                let item_indent = ctx.lines[i].indent;
2369                let min_continuation_indent = if ctx.flavor.requires_strict_list_indent() {
2370                    // Use 4-space relative indent from the list item's nesting level
2371                    item_indent + (base_marker_len - item_indent).max(4)
2372                } else {
2373                    marker_len
2374                };
2375                let content_continuation_indent = base_marker_len;
2376
2377                // Track lines and their types (content, code block, fence, nested list)
2378                #[derive(Clone)]
2379                enum LineType {
2380                    Content(String, usize),           // content and 1-indexed line number
2381                    CodeBlock(String, usize),         // content and original indent
2382                    SemanticLine(String), // Lines starting with NOTE:, WARNING:, etc that should stay separate
2383                    SnippetLine(String),  // MkDocs Snippets delimiters (-8<-) that must stay on their own line
2384                    DivMarker(String),    // Quarto/Pandoc div markers (::: opening or closing)
2385                    AdmonitionHeader(String, usize), // header text (e.g. "!!! note") and original indent
2386                    AdmonitionContent(String, usize), // body content text and original indent
2387                    Table(String, usize), // GFM table row, preserved verbatim with original indent
2388                    Empty,
2389                }
2390
2391                let start_idx = i;
2392                // A marker line whose content is one whole `$$...$$` expression
2393                // renders as a display block, so it keeps the line it was written
2394                // on and the prose under it starts a paragraph of its own. The
2395                // code-block carrier re-emits it unchanged after the marker.
2396                //
2397                // The marker keeps one padding space and leaves the rest at the
2398                // head of the content, and the carrier writes the marker as the
2399                // author spelled it, padding included. The carrier therefore
2400                // holds the content with its leading whitespace off, so the
2401                // padding is written once.
2402                //
2403                // A marker that cannot interrupt a paragraph, such as an
2404                // ordered one not starting at one, can sit inside a code span
2405                // the paragraph above opened, and its content is code then.
2406                // The marker line can just as well be the one that opens the
2407                // span, closing on a line still to come.
2408                let mut list_item_lines: Vec<LineType> = if (is_self_contained_display_math_line(&first_content)
2409                    || self.line_is_standalone_bracket_math(i + 1, ctx, config))
2410                    && !line_touches_multiline_code_span(&code_span_touches, i + 1)
2411                {
2412                    vec![LineType::CodeBlock(first_content.trim_start().to_string(), marker_len)]
2413                } else {
2414                    vec![LineType::Content(first_content, i + 1)]
2415                };
2416                // Set when collection stops at a nested list item or a nested
2417                // blockquote that belongs to this item. Such structure is reflowed
2418                // independently and is therefore absent from `list_item_lines`/`blocks`,
2419                // but it still keeps the emitted item spanning multiple physical lines,
2420                // which the MD030 multi-line spacing decision below must account for.
2421                let mut has_trailing_nested_structure = false;
2422                i += 1;
2423
2424                // Collect continuation lines using ctx.lines for metadata
2425                while i < lines.len() {
2426                    let line_info = &ctx.lines[i];
2427
2428                    // Use pre-computed is_blank from ctx
2429                    if line_info.is_blank {
2430                        // Empty line - check if next line is indented (part of list item)
2431                        if i + 1 < lines.len() {
2432                            let next_info = &ctx.lines[i + 1];
2433
2434                            // Check if next line is indented enough to be continuation
2435                            if !next_info.is_blank && next_info.indent >= min_continuation_indent {
2436                                // This blank line is between paragraphs/blocks in the list item
2437                                list_item_lines.push(LineType::Empty);
2438                                i += 1;
2439                                continue;
2440                            }
2441                        }
2442                        // No indented line after blank, end of list item
2443                        break;
2444                    }
2445
2446                    // Use pre-computed indent from ctx
2447                    let indent = line_info.indent;
2448
2449                    // Valid continuation must be indented at least content_continuation_indent.
2450                    // For non-blank continuation, use marker_len (e.g. 2 for "- ").
2451                    // MkDocs strict 4-space requirement applies only after blank lines.
2452                    if indent >= content_continuation_indent {
2453                        let trimmed = line_info.content(ctx.content).trim();
2454
2455                        // Check for MkDocs admonition lines inside list items BEFORE
2456                        // checking in_code_block. Lines inside code blocks within
2457                        // admonitions have both in_admonition and in_code_block set;
2458                        // admonition membership takes priority so the entire admonition
2459                        // structure (including embedded code blocks) is preserved.
2460                        if line_info.in_admonition {
2461                            let raw_content = line_info.content(ctx.content);
2462                            if mkdocs_admonitions::is_admonition_start(raw_content) {
2463                                let header_text = raw_content[indent..].trim_end().to_string();
2464                                list_item_lines.push(LineType::AdmonitionHeader(header_text, indent));
2465                            } else {
2466                                let body_text = raw_content[indent..].trim_end().to_string();
2467                                list_item_lines.push(LineType::AdmonitionContent(body_text, indent));
2468                            }
2469                            i += 1;
2470                            continue;
2471                        }
2472
2473                        // Use pre-computed in_code_block from ctx
2474                        if line_info.in_code_block {
2475                            list_item_lines.push(LineType::CodeBlock(
2476                                line_info.content(ctx.content)[indent..].to_string(),
2477                                indent,
2478                            ));
2479                            i += 1;
2480                            continue;
2481                        }
2482
2483                        // A multi-line display-math block inside the item is verbatim:
2484                        // its line breaks carry meaning (see
2485                        // `line_in_multiline_math_block`), so reuse the code-block
2486                        // carrier to re-emit it unchanged.
2487                        if self.line_in_multiline_math_block(i + 1, ctx, config) {
2488                            list_item_lines.push(LineType::CodeBlock(
2489                                line_info.content(ctx.content)[indent..].to_string(),
2490                                indent,
2491                            ));
2492                            i += 1;
2493                            continue;
2494                        }
2495
2496                        // A blockquote nested inside the list item is reflowed by the
2497                        // blockquote-aware path (it preserves the `>` prefix, including the
2498                        // list indent), not as list-item prose. Collecting it as Content
2499                        // would strip the markers and reflow `>` as words, collapsing the
2500                        // blank `>` line and dropping `>` from wrapped continuations. End
2501                        // the item here so the outer loop routes the blockquote line to
2502                        // generate_blockquote_paragraph_fix. Uncollect a pending blank so
2503                        // the separator between the list prose and the blockquote survives.
2504                        if line_info.blockquote.is_some() {
2505                            has_trailing_nested_structure = true;
2506                            if matches!(list_item_lines.last(), Some(LineType::Empty)) {
2507                                list_item_lines.pop();
2508                                i -= 1;
2509                            }
2510                            break;
2511                        }
2512
2513                        // Check if this is a SIBLING list item (breaks parent)
2514                        // Nested lists are indented >= marker_len and are PART of the parent item
2515                        // Siblings are at indent < marker_len (at or before parent marker)
2516                        if is_list_item(trimmed) && indent < marker_len {
2517                            // This is a sibling item at same or higher level - end parent item
2518                            break;
2519                        }
2520
2521                        // Nested list items are always processed independently
2522                        // by the outer loop, so break when we encounter one.
2523                        // If a blank line was collected before this, uncollect it
2524                        // so the outer loop preserves the blank between parent and nested.
2525                        if is_list_item(trimmed) && indent >= marker_len {
2526                            has_trailing_nested_structure = true;
2527                            if matches!(list_item_lines.last(), Some(LineType::Empty)) {
2528                                list_item_lines.pop();
2529                                i -= 1;
2530                            }
2531                            break;
2532                        }
2533
2534                        // Normal continuation vs indented code block.
2535                        // Use min_continuation_indent for the threshold since
2536                        // code blocks start 4 spaces beyond the expected content
2537                        // level (which is min_continuation_indent for MkDocs).
2538                        if indent <= min_continuation_indent + 3 {
2539                            // Extract content (remove indentation and trailing whitespace)
2540                            // Preserve hard breaks (2 trailing spaces) while removing excessive whitespace
2541                            // See: https://github.com/rvben/rumdl/issues/76
2542                            let content = trim_preserving_hard_break(&line_info.content(ctx.content)[indent..]);
2543
2544                            // Check if this is a div marker (::: opening or closing)
2545                            // These must be preserved on their own line, not merged into paragraphs
2546                            if line_info.is_div_marker {
2547                                list_item_lines.push(LineType::DivMarker(content));
2548                            }
2549                            // A fence marker opens or closes a code block, and a line
2550                            // that is one whole `$$...$$` expression renders as a
2551                            // display block. Both keep the line they were written on,
2552                            // so the code-block carrier re-emits them unchanged
2553                            // between the prose above and below. A line touched by a
2554                            // code span crossing one of its boundaries is code, not
2555                            // such a block.
2556                            else if is_fence_marker(&content)
2557                                || ((is_self_contained_display_math_line(&content)
2558                                    || self.line_is_standalone_bracket_math(i + 1, ctx, config))
2559                                    && !line_touches_multiline_code_span(&code_span_touches, i + 1))
2560                            {
2561                                list_item_lines.push(LineType::CodeBlock(content, indent));
2562                            }
2563                            // Check if this is a semantic line (NOTE:, WARNING:, etc.)
2564                            else if is_semantic_line(&content) {
2565                                list_item_lines.push(LineType::SemanticLine(content));
2566                            }
2567                            // Check if this is a snippet block delimiter (-8<- or --8<--)
2568                            // These must be preserved on their own lines for MkDocs Snippets extension
2569                            else if is_snippet_block_delimiter(&content) {
2570                                list_item_lines.push(LineType::SnippetLine(content));
2571                            }
2572                            // Check if this is a GFM table row. Tables nested inside list
2573                            // items must be preserved verbatim — joining them with prose
2574                            // breaks the column structure.
2575                            //
2576                            // `is_potential_table_row` is intentionally permissive at the
2577                            // row level: any line with `|` and 2+ cells qualifies. To avoid
2578                            // misclassifying prose continuation lines that contain a literal
2579                            // pipe (e.g. "use grep | sort to ..."), require one of:
2580                            //   - the row is pipe-bordered (`| ... |`), the canonical form
2581                            //     for tables nested in lists; or
2582                            //   - the next line is a delimiter row (this is a header); or
2583                            //   - the previous classified line was already a Table (this is
2584                            //     a continuation row).
2585                            else if TableUtils::is_potential_table_row_with_flavor(&content, ctx.flavor) && {
2586                                let pipe_bordered = content.trim().starts_with('|') && content.trim().ends_with('|');
2587                                let next_is_delim = ctx
2588                                    .lines
2589                                    .get(i + 1)
2590                                    .is_some_and(|next| TableUtils::is_delimiter_row(next.content(ctx.content)));
2591                                let prev_was_table = matches!(list_item_lines.last(), Some(LineType::Table(..)));
2592                                pipe_bordered || next_is_delim || prev_was_table
2593                            } {
2594                                list_item_lines.push(LineType::Table(content, indent));
2595                            } else {
2596                                list_item_lines.push(LineType::Content(content, i + 1));
2597                            }
2598                            i += 1;
2599                        } else {
2600                            // indent >= min_continuation_indent + 4: indented code block
2601                            list_item_lines.push(LineType::CodeBlock(
2602                                line_info.content(ctx.content)[indent..].to_string(),
2603                                indent,
2604                            ));
2605                            i += 1;
2606                        }
2607                    } else {
2608                        // Not indented enough, end of list item
2609                        break;
2610                    }
2611                }
2612
2613                // Determine the output continuation indent.
2614                // Normalize/Default modes canonicalize to min_continuation_indent
2615                // (fixing over-indented continuation). Semantic/SentencePerLine
2616                // modes preserve the user's actual indent since they only fix
2617                // line breaking, not indentation.
2618                let indent_size = match config.reflow_mode {
2619                    ReflowMode::SemanticLineBreaks | ReflowMode::SentencePerLine => {
2620                        // Find indent of the first plain text continuation line,
2621                        // skipping the marker line (index 0), nested list items,
2622                        // code blocks, and blank lines.
2623                        list_item_lines
2624                            .iter()
2625                            .enumerate()
2626                            .skip(1)
2627                            .find_map(|(k, lt)| {
2628                                if matches!(lt, LineType::Content(..)) {
2629                                    Some(ctx.lines[list_start + k].indent)
2630                                } else {
2631                                    None
2632                                }
2633                            })
2634                            .unwrap_or(min_continuation_indent)
2635                    }
2636                    _ => min_continuation_indent,
2637                };
2638                // For checkbox items in mkdocs flavor, enforce minimum indent so
2639                // continuation lines use the structural list indent (4), not the
2640                // content-aligned indent (6) which Python-Markdown doesn't support
2641                let has_checkbox = base_marker_len < marker_len;
2642                let indent_size = if has_checkbox && ctx.flavor.requires_strict_list_indent() {
2643                    indent_size.max(min_continuation_indent)
2644                } else {
2645                    indent_size
2646                };
2647
2648                // Split list_item_lines into blocks (paragraphs, code blocks, nested lists, semantic lines, and HTML blocks)
2649                let mut builder = BlockBuilder::new_with_start_line(start_idx + 1);
2650                for line in &list_item_lines {
2651                    match line {
2652                        LineType::Empty => builder.feed_blank_line(),
2653                        LineType::Content(content, _) => builder.feed_content(content),
2654                        LineType::CodeBlock(content, indent) => builder.feed_code_line(content, *indent),
2655                        LineType::SemanticLine(content) => builder.feed_semantic_line(content),
2656                        LineType::SnippetLine(content) => builder.feed_snippet_line(content),
2657                        LineType::DivMarker(content) => builder.feed_div_marker(content),
2658                        LineType::AdmonitionHeader(header_text, indent) => {
2659                            builder.feed_admonition_header(header_text, *indent)
2660                        }
2661                        LineType::AdmonitionContent(content, indent) => {
2662                            builder.feed_admonition_content(content, *indent)
2663                        }
2664                        LineType::Table(content, indent) => builder.feed_table_line(content, *indent),
2665                    }
2666                }
2667                let blocks = builder.finalize();
2668
2669                // Helper: check if a line (raw source or stripped content) is exempt
2670                // from line-length checks. Link reference definitions are always exempt;
2671                // standalone link/image lines are exempt when strict mode is off.
2672                // Also checks content after stripping list markers, since list item
2673                // continuation lines may contain link ref defs.
2674                let is_exempt_line = |raw_line: &str, line_num: usize| -> bool {
2675                    let trimmed = raw_line.trim();
2676                    // Link reference definitions: always exempt
2677                    if trimmed.starts_with('[') && trimmed.contains("]:") && LINK_REF_PATTERN.is_match(trimmed) {
2678                        return true;
2679                    }
2680                    // Also check after stripping list markers (for list item content)
2681                    if is_list_item(trimmed) {
2682                        let (_, content) = extract_list_marker_and_content(trimmed);
2683                        let content_trimmed = content.trim();
2684                        if content_trimmed.starts_with('[')
2685                            && content_trimmed.contains("]:")
2686                            && LINK_REF_PATTERN.is_match(content_trimmed)
2687                        {
2688                            return true;
2689                        }
2690                    }
2691                    // Standalone link/image lines: exempt when not strict
2692                    if standalone_link_ends_paragraph(ctx, line_num, config) {
2693                        return true;
2694                    }
2695                    // HTML-only lines: exempt when not strict
2696                    if !config.strict && is_html_only_line(raw_line) {
2697                        return true;
2698                    }
2699                    false
2700                };
2701
2702                // Check if reflowing is needed (only for content paragraphs, not code blocks or nested lists)
2703                // Exclude link reference definitions and standalone link lines from content
2704                // so they don't pollute combined_content or trigger false reflow.
2705                let content_lines: Vec<String> = list_item_lines
2706                    .iter()
2707                    .filter_map(|line| {
2708                        if let LineType::Content(s, line_num) = line {
2709                            if is_exempt_line(s, *line_num) {
2710                                return None;
2711                            }
2712                            Some(s.clone())
2713                        } else {
2714                            None
2715                        }
2716                    })
2717                    .collect();
2718
2719                // Check if we need to reflow this list item
2720                // We check the combined content to see if it exceeds length limits
2721                let combined_content = content_lines.join(" ").trim().to_string();
2722
2723                // Helper to check if we should reflow in normalize mode
2724                let should_normalize = || {
2725                    // Don't normalize if the list item only contains nested lists, code blocks, or semantic lines
2726                    // DO normalize if it has plain text content that spans multiple lines
2727                    let has_code_blocks = blocks.iter().any(|b| matches!(b, Block::Code { .. }));
2728                    let has_semantic_lines = blocks.iter().any(|b| matches!(b, Block::SemanticLine(_)));
2729                    let has_snippet_lines = blocks.iter().any(|b| matches!(b, Block::SnippetLine(_)));
2730                    let has_div_markers = blocks.iter().any(|b| matches!(b, Block::DivMarker(_)));
2731                    let has_admonitions = blocks.iter().any(|b| matches!(b, Block::Admonition { .. }));
2732                    let has_tables = blocks.iter().any(|b| matches!(b, Block::Table { .. }));
2733                    let has_paragraphs = blocks.iter().any(|b| matches!(b, Block::Paragraph(_)));
2734
2735                    // If we have structural blocks but no paragraphs, don't normalize
2736                    if (has_code_blocks
2737                        || has_semantic_lines
2738                        || has_snippet_lines
2739                        || has_div_markers
2740                        || has_admonitions
2741                        || has_tables)
2742                        && !has_paragraphs
2743                    {
2744                        return false;
2745                    }
2746
2747                    // If we have paragraphs, check if they span multiple lines or there are multiple blocks
2748                    if has_paragraphs {
2749                        // Count only paragraphs that contain at least one non-exempt line.
2750                        // Paragraphs consisting entirely of link ref defs or standalone links
2751                        // should not trigger normalization.
2752                        let paragraph_count = blocks
2753                            .iter()
2754                            .filter(|b| {
2755                                if let Block::Paragraph(para_lines) = b {
2756                                    !para_lines
2757                                        .iter()
2758                                        .all(|(line, line_num)| is_exempt_line(line, *line_num))
2759                                } else {
2760                                    false
2761                                }
2762                            })
2763                            .count();
2764                        if paragraph_count > 1 {
2765                            // Multiple non-exempt paragraph blocks should be normalized
2766                            return true;
2767                        }
2768
2769                        // Single paragraph block: normalize if it has multiple content lines
2770                        if content_lines.len() > 1 {
2771                            return true;
2772                        }
2773                    }
2774
2775                    false
2776                };
2777
2778                // Integrate MD030 list-marker spacing (and MD007's text-aligned
2779                // continuation). In Default/Normalize modes — the modes that already
2780                // canonicalize spacing/indent — derive the number of spaces after the
2781                // marker from the configured MD030 values instead of forcing a single
2782                // space, then align continuation lines to the resulting content column.
2783                // Sentence/Semantic modes only adjust line breaks, so they keep the
2784                // marker spacing and indentation already present in the source.
2785                //
2786                // With default MD030 (a single space everywhere) the rebuilt marker is
2787                // byte-identical to the source marker, so this is a no-op and existing
2788                // behaviour is preserved; only a non-default MD030 changes the output.
2789                // The MkDocs flavor enforces a rigid structural indent (4 spaces,
2790                // capped via max_list_continuation_indent) that Python-Markdown
2791                // requires; leave its specialized handling untouched.
2792                let (marker, indent_size, code_indent_shift) =
2793                    if matches!(config.reflow_mode, ReflowMode::Default | ReflowMode::Normalize)
2794                        && !ctx.flavor.requires_strict_list_indent()
2795                        && let Some(li) = ctx.lines[list_start].list_item.as_deref()
2796                    {
2797                        let bullet_len = li.marker.len();
2798                        // The checkbox (e.g. `[ ] `) is content, not part of the list
2799                        // marker MD030 governs; carry it over verbatim after the spacing.
2800                        let checkbox_tail = marker[base_marker_len..].to_string();
2801                        // Shift this item right by its ancestors' cumulative marker
2802                        // widening so a nested item stays under its parent's (widened)
2803                        // content column. Zero for top-level items and for the whole
2804                        // tree under default MD030, where the source indent is preserved
2805                        // verbatim (byte-identical output).
2806                        let ancestor_shift = list_shift_stack.last().map_or(0isize, |&(_, shift)| shift);
2807                        let shifted_indent = (item_indent as isize + ancestor_shift).max(0) as usize;
2808                        let indent_prefix = if ancestor_shift == 0 {
2809                            marker[..item_indent].to_string()
2810                        } else {
2811                            " ".repeat(shifted_indent)
2812                        };
2813
2814                        // Decide single- vs multi-line spacing from the *rewritten* shape,
2815                        // not the source. A multi-line source is not enough: plain prose
2816                        // continuation collapses onto the marker line during reflow, so a
2817                        // two-line bullet that fits becomes a single physical line and must
2818                        // use MD030's single-line spacing (otherwise MD013 emits a result
2819                        // that MD030 immediately rewrites). The emitted item stays
2820                        // multi-line only when reflow cannot collapse it:
2821                        //   - the prose wraps past the line length, or
2822                        //   - a structural block remains (code, table, admonition, semantic
2823                        //     line, snippet, div marker, HTML) that is not joinable prose, or
2824                        //   - more than one paragraph remains (blank-separated), or
2825                        //   - a nested list/blockquote follows (reflowed independently, so it
2826                        //     is absent from `blocks` but still keeps the item multi-line).
2827                        // The wrap test uses the single-line content column so it is
2828                        // independent of the spacing we are about to choose (avoiding a
2829                        // circular result). `ol-align-column` ignores this flag entirely in
2830                        // expected_spaces(), so ordered lists are unaffected.
2831                        //
2832                        // This is the rewritten-shape counterpart of MD030's
2833                        // `is_multi_line_list_item` (which keys off the *source*). The two
2834                        // are related but technically distinct and intentionally separate;
2835                        // if the notion of "multi-line" changes in one, revisit the other.
2836                        let single_col = shifted_indent
2837                            + bullet_len
2838                            + self.list_spacing.expected_spaces(li.is_ordered, false, bullet_len)
2839                            + checkbox_tail.len();
2840                        let prose_wraps = !combined_content.is_empty()
2841                            && self
2842                                .calculate_effective_length(&format!("{}{combined_content}", " ".repeat(single_col)))
2843                                > config.line_length.effective_limit();
2844                        let has_structural_block = blocks.iter().any(|b| !matches!(b, Block::Paragraph(_)));
2845                        let multiple_paragraphs =
2846                            blocks.iter().filter(|b| matches!(b, Block::Paragraph(_))).count() > 1;
2847                        let is_multi =
2848                            prose_wraps || has_structural_block || multiple_paragraphs || has_trailing_nested_structure;
2849
2850                        let spaces = self.list_spacing.expected_spaces(li.is_ordered, is_multi, bullet_len);
2851                        let new_marker = format!("{indent_prefix}{}{}{checkbox_tail}", li.marker, " ".repeat(spaces));
2852                        let new_col = new_marker.chars().count();
2853                        let shift = new_col as isize - source_content_col as isize;
2854                        (new_marker, new_col, shift)
2855                    } else {
2856                        // MkDocs enforces a rigid structural indent, so the item is emitted
2857                        // exactly as written and its nested blocks never move. Re-emitting
2858                        // the normalized marker here would narrow the content column while
2859                        // leaving those blocks behind.
2860                        let marker = source_marker.map_or(marker, |m| m.text);
2861                        (marker, indent_size, 0isize)
2862                    };
2863                let expected_indent = " ".repeat(indent_size);
2864
2865                // A colon-led line with a line of its paragraph before it opens a
2866                // definition and makes the item a definition list. Joining the
2867                // lines flattens that into prose, so the item is left as the
2868                // author wrote it. The first line of each paragraph is prose
2869                // whatever it starts with, since a definition needs a term on
2870                // the line before it. Content lines arrive with the item's own
2871                // indentation already off, which is what the marker's
2872                // indentation is counted from.
2873                let contains_definition_list = blocks.iter().any(|block| match block {
2874                    Block::Paragraph(para_lines) => para_lines
2875                        .iter()
2876                        .skip(1)
2877                        .any(|(line, _)| crate::utils::text_reflow::is_definition_list_marker(line)),
2878                    _ => false,
2879                });
2880
2881                let needs_reflow = !contains_definition_list
2882                    && !holds_definition_list(ctx, list_start, i - 1)
2883                    && match config.reflow_mode {
2884                        ReflowMode::Normalize => {
2885                            // Only reflow if:
2886                            // 1. Any non-exempt paragraph, when joined, exceeds the limit, OR
2887                            // 2. Any admonition content line exceeds the limit, OR
2888                            // 3. The list item should be normalized (has multi-line plain text)
2889                            let any_paragraph_exceeds = blocks.iter().any(|block| match block {
2890                                Block::Paragraph(para_lines) => {
2891                                    if para_lines
2892                                        .iter()
2893                                        .all(|(line, line_num)| is_exempt_line(line, *line_num))
2894                                    {
2895                                        return false;
2896                                    }
2897                                    let joined =
2898                                        para_lines.iter().map(|(l, _)| l.as_str()).collect::<Vec<_>>().join(" ");
2899                                    let with_marker = format!("{}{}", " ".repeat(indent_size), joined.trim());
2900                                    self.calculate_effective_length(&with_marker) > config.line_length.get()
2901                                }
2902                                Block::Admonition {
2903                                    content_lines,
2904                                    header_indent,
2905                                    ..
2906                                } => content_lines.iter().any(|(content, indent)| {
2907                                    if content.is_empty() {
2908                                        return false;
2909                                    }
2910                                    let with_indent = format!("{}{}", " ".repeat(*indent.max(header_indent)), content);
2911                                    self.calculate_effective_length(&with_indent) > config.line_length.get()
2912                                }),
2913                                _ => false,
2914                            });
2915                            if any_paragraph_exceeds {
2916                                true
2917                            } else {
2918                                should_normalize()
2919                            }
2920                        }
2921                        ReflowMode::SentencePerLine => {
2922                            // Check if list item has multiple sentences
2923                            let sentences = split_into_sentences(
2924                                &combined_content,
2925                                Some(&defined_references),
2926                                config.require_sentence_capital,
2927                            );
2928                            sentences.len() > 1
2929                        }
2930                        ReflowMode::SemanticLineBreaks => {
2931                            let sentences = split_into_sentences(
2932                                &combined_content,
2933                                Some(&defined_references),
2934                                config.require_sentence_capital,
2935                            );
2936                            sentences.len() > 1
2937                                || (list_start..i).any(|line_idx| {
2938                                    let line = lines[line_idx];
2939                                    let trimmed = line.trim();
2940                                    if trimmed.is_empty() || is_exempt_line(line, line_idx + 1) {
2941                                        return false;
2942                                    }
2943                                    self.calculate_effective_length(line) > config.line_length.get()
2944                                })
2945                        }
2946                        ReflowMode::Default => {
2947                            // In default mode, only reflow if any individual non-exempt line exceeds limit
2948                            (list_start..i).any(|line_idx| {
2949                                let line = lines[line_idx];
2950                                let trimmed = line.trim();
2951                                // Skip blank lines and exempt lines
2952                                if trimmed.is_empty() || is_exempt_line(line, line_idx + 1) {
2953                                    return false;
2954                                }
2955                                self.calculate_effective_length(line) > config.line_length.get()
2956                            })
2957                        }
2958                    };
2959
2960                // Record this item's frame so its nested children inherit the shift.
2961                // Only a reflowed item's marker actually moves; an unreflowed one keeps
2962                // its source position and so contributes no shift to its children. The
2963                // threshold that decides which following lines are inside this item is
2964                // the normalized marker width, NOT `source_content_col`: the collection
2965                // loop above gathers continuations by that same width, so the frame
2966                // boundary must match it or the two would disagree about ownership of
2967                // lines indented between the normalized and the source content column.
2968                list_shift_stack.push((marker_len, if needs_reflow { code_indent_shift } else { 0 }));
2969
2970                if needs_reflow {
2971                    let start_range = ctx.whole_line_byte_range(list_start + 1);
2972                    let end_line = i - 1;
2973                    let end_range = if end_line == lines.len() - 1 && !ctx.content.ends_with('\n') {
2974                        ctx.line_text_byte_range(end_line + 1, 1, lines[end_line].len() + 1)
2975                    } else {
2976                        ctx.whole_line_byte_range(end_line + 1)
2977                    };
2978                    let byte_range = start_range.start..end_range.end;
2979
2980                    // Reflow each block (paragraphs only, preserve code blocks)
2981                    // When line_length = 0 (no limit), use a very large value for reflow
2982                    let reflow_line_length = if config.line_length.is_unlimited() {
2983                        usize::MAX
2984                    } else {
2985                        config.line_length.get().saturating_sub(indent_size).max(1)
2986                    };
2987                    let reflow_options = Self::reflow_options(ctx, config, reflow_line_length);
2988
2989                    let mut result: Vec<String> = Vec::new();
2990                    let mut is_first_block = true;
2991
2992                    for (block_idx, block) in blocks.iter().enumerate() {
2993                        match block {
2994                            Block::Paragraph(para_lines) => {
2995                                // If every line in this paragraph is exempt (link ref defs,
2996                                // standalone links), preserve the paragraph verbatim instead
2997                                // of reflowing it. Reflowing would corrupt link ref defs.
2998                                let all_exempt = para_lines
2999                                    .iter()
3000                                    .all(|(line, line_num)| is_exempt_line(line, *line_num));
3001
3002                                if all_exempt {
3003                                    for (idx, (line, _)) in para_lines.iter().enumerate() {
3004                                        if is_first_block && idx == 0 {
3005                                            result.push(format!("{marker}{line}"));
3006                                            is_first_block = false;
3007                                        } else {
3008                                            result.push(format!("{expected_indent}{line}"));
3009                                        }
3010                                    }
3011                                } else {
3012                                    // Split the paragraph into segments at hard break boundaries
3013                                    // Each segment can be reflowed independently
3014                                    let segments = split_into_segments(para_lines);
3015
3016                                    for (segment_idx, segment) in segments.iter().enumerate() {
3017                                        // Check if this segment ends with a hard break and what type
3018                                        let hard_break_type = segment.last().and_then(|(line, _)| {
3019                                            let line = line.strip_suffix('\r').unwrap_or(line);
3020                                            if line.ends_with('\\') {
3021                                                Some("\\")
3022                                            } else if line.ends_with("  ") {
3023                                                Some("  ")
3024                                            } else {
3025                                                None
3026                                            }
3027                                        });
3028
3029                                        // Join and reflow the segment (removing the hard break marker for processing)
3030                                        let segment_for_reflow: Vec<String> = segment
3031                                            .iter()
3032                                            .map(|(line, _)| {
3033                                                // Strip hard break marker (2 spaces or backslash) for reflow processing
3034                                                if line.ends_with('\\') {
3035                                                    line[..line.len() - 1].trim_end().to_string()
3036                                                } else if line.ends_with("  ") {
3037                                                    line[..line.len() - 2].trim_end().to_string()
3038                                                } else {
3039                                                    line.clone()
3040                                                }
3041                                            })
3042                                            .collect();
3043
3044                                        let segment_text = segment_for_reflow.join(" ").trim().to_string();
3045                                        if !segment_text.is_empty() {
3046                                            let reflowed =
3047                                                crate::utils::text_reflow::reflow_line(&segment_text, &reflow_options);
3048
3049                                            if is_first_block && segment_idx == 0 {
3050                                                // First segment of first block starts with marker
3051                                                result.push(format!("{marker}{}", reflowed[0]));
3052                                                for line in reflowed.iter().skip(1) {
3053                                                    result.push(format!("{expected_indent}{line}"));
3054                                                }
3055                                                is_first_block = false;
3056                                            } else {
3057                                                // Subsequent segments
3058                                                for line in reflowed {
3059                                                    result.push(format!("{expected_indent}{line}"));
3060                                                }
3061                                            }
3062
3063                                            // If this segment had a hard break, add it back to the last line
3064                                            // Preserve the original hard break format (backslash or two spaces)
3065                                            if let Some(break_marker) = hard_break_type
3066                                                && let Some(last_line) = result.last_mut()
3067                                            {
3068                                                last_line.push_str(break_marker);
3069                                            }
3070                                        }
3071                                    }
3072                                }
3073
3074                                // Add blank line after paragraph block if there's a next block.
3075                                // Check if next block is a code block that doesn't want a preceding blank.
3076                                // Also don't add blank lines before snippet lines (they should stay tight).
3077                                // Only add if not already ending with one (avoids double blanks).
3078                                if block_idx < blocks.len() - 1 {
3079                                    let next_block = &blocks[block_idx + 1];
3080                                    let should_add_blank = match next_block {
3081                                        Block::Code {
3082                                            has_preceding_blank, ..
3083                                        } => *has_preceding_blank,
3084                                        Block::Table {
3085                                            has_preceding_blank, ..
3086                                        } => *has_preceding_blank,
3087                                        Block::SnippetLine(_) | Block::DivMarker(_) => false,
3088                                        _ => true, // For all other blocks, add blank line
3089                                    };
3090                                    if should_add_blank && result.last().is_none_or(|s: &String| !s.is_empty()) {
3091                                        result.push(String::new());
3092                                    }
3093                                }
3094                            }
3095                            Block::Code {
3096                                lines: code_lines,
3097                                has_preceding_blank: _,
3098                            } => {
3099                                // Preserve code blocks as-is with original indentation
3100                                // NOTE: Blank line before code block is handled by the previous block
3101                                // (see paragraph block's logic above)
3102
3103                                for (idx, (content, orig_indent)) in code_lines.iter().enumerate() {
3104                                    if is_first_block && idx == 0 {
3105                                        // First line of first block gets marker
3106                                        result.push(format!(
3107                                            "{marker}{}",
3108                                            " ".repeat(orig_indent - marker_len) + content.as_str()
3109                                        ));
3110                                        is_first_block = false;
3111                                    } else if content.is_empty() {
3112                                        result.push(String::new());
3113                                    } else {
3114                                        // Shift nested code with the marker so it stays
3115                                        // aligned under content when MD030 widens spacing.
3116                                        result.push(format!(
3117                                            "{}{}",
3118                                            " ".repeat((*orig_indent as isize + code_indent_shift).max(0) as usize),
3119                                            content
3120                                        ));
3121                                    }
3122                                }
3123                            }
3124                            Block::SemanticLine(content) => {
3125                                // Preserve semantic lines (NOTE:, WARNING:, etc.) as-is on their own line.
3126                                // Only add blank before if not already ending with one.
3127                                if !is_first_block && result.last().is_none_or(|s: &String| !s.is_empty()) {
3128                                    result.push(String::new());
3129                                }
3130
3131                                if is_first_block {
3132                                    // First block starts with marker
3133                                    result.push(format!("{marker}{content}"));
3134                                    is_first_block = false;
3135                                } else {
3136                                    // Subsequent blocks use expected indent
3137                                    result.push(format!("{expected_indent}{content}"));
3138                                }
3139
3140                                // Add blank line after semantic line if there's a next block.
3141                                // Only add if not already ending with one.
3142                                if block_idx < blocks.len() - 1 {
3143                                    let next_block = &blocks[block_idx + 1];
3144                                    let should_add_blank = match next_block {
3145                                        Block::Code {
3146                                            has_preceding_blank, ..
3147                                        } => *has_preceding_blank,
3148                                        Block::Table {
3149                                            has_preceding_blank, ..
3150                                        } => *has_preceding_blank,
3151                                        Block::SnippetLine(_) | Block::DivMarker(_) => false,
3152                                        _ => true, // For all other blocks, add blank line
3153                                    };
3154                                    if should_add_blank && result.last().is_none_or(|s: &String| !s.is_empty()) {
3155                                        result.push(String::new());
3156                                    }
3157                                }
3158                            }
3159                            Block::SnippetLine(content) => {
3160                                // Preserve snippet delimiters (-8<-) as-is on their own line
3161                                // Unlike semantic lines, snippet lines don't add extra blank lines
3162                                if is_first_block {
3163                                    // First block starts with marker
3164                                    result.push(format!("{marker}{content}"));
3165                                    is_first_block = false;
3166                                } else {
3167                                    // Subsequent blocks use expected indent
3168                                    result.push(format!("{expected_indent}{content}"));
3169                                }
3170                                // No blank lines added before or after snippet delimiters
3171                            }
3172                            Block::DivMarker(content) => {
3173                                // Preserve div markers (::: opening or closing) as-is on their own line
3174                                if is_first_block {
3175                                    result.push(format!("{marker}{content}"));
3176                                    is_first_block = false;
3177                                } else {
3178                                    result.push(format!("{expected_indent}{content}"));
3179                                }
3180                            }
3181                            Block::Html {
3182                                lines: html_lines,
3183                                has_preceding_blank: _,
3184                            } => {
3185                                // Preserve HTML blocks exactly as-is with original indentation
3186                                // NOTE: Blank line before HTML block is handled by the previous block
3187
3188                                for (idx, line) in html_lines.iter().enumerate() {
3189                                    if is_first_block && idx == 0 {
3190                                        // First line of first block gets marker
3191                                        result.push(format!("{marker}{line}"));
3192                                        is_first_block = false;
3193                                    } else if line.is_empty() {
3194                                        // Preserve blank lines inside HTML blocks
3195                                        result.push(String::new());
3196                                    } else {
3197                                        // Preserve lines with their original content (already includes indentation)
3198                                        result.push(format!("{expected_indent}{line}"));
3199                                    }
3200                                }
3201
3202                                // Add blank line after HTML block if there's a next block.
3203                                // Only add if not already ending with one (avoids double blanks
3204                                // when the HTML block itself contained a trailing blank line).
3205                                if block_idx < blocks.len() - 1 {
3206                                    let next_block = &blocks[block_idx + 1];
3207                                    let should_add_blank = match next_block {
3208                                        Block::Code {
3209                                            has_preceding_blank, ..
3210                                        } => *has_preceding_blank,
3211                                        Block::Html {
3212                                            has_preceding_blank, ..
3213                                        } => *has_preceding_blank,
3214                                        Block::Table {
3215                                            has_preceding_blank, ..
3216                                        } => *has_preceding_blank,
3217                                        Block::SnippetLine(_) | Block::DivMarker(_) => false,
3218                                        _ => true, // For all other blocks, add blank line
3219                                    };
3220                                    if should_add_blank && result.last().is_none_or(|s: &String| !s.is_empty()) {
3221                                        result.push(String::new());
3222                                    }
3223                                }
3224                            }
3225                            Block::Table {
3226                                lines: table_lines,
3227                                has_preceding_blank: _,
3228                            } => {
3229                                // Preserve table rows verbatim with their original indentation.
3230                                // Reflowing rows would corrupt column alignment and inject `|`
3231                                // characters mid-paragraph (issue #590).
3232                                // The leading blank line is emitted by the previous block.
3233                                for (idx, (content, orig_indent)) in table_lines.iter().enumerate() {
3234                                    if is_first_block && idx == 0 {
3235                                        // First line of first block gets the list marker
3236                                        result.push(format!(
3237                                            "{marker}{}",
3238                                            " ".repeat(orig_indent.saturating_sub(marker_len)) + content.as_str()
3239                                        ));
3240                                        is_first_block = false;
3241                                    } else {
3242                                        // Shift nested table rows with the marker so they
3243                                        // stay aligned when MD030 widens marker spacing.
3244                                        result.push(format!(
3245                                            "{}{}",
3246                                            " ".repeat((*orig_indent as isize + code_indent_shift).max(0) as usize),
3247                                            content
3248                                        ));
3249                                    }
3250                                }
3251
3252                                // Add blank line after table block if there's a next block.
3253                                if block_idx < blocks.len() - 1 {
3254                                    let next_block = &blocks[block_idx + 1];
3255                                    let should_add_blank = match next_block {
3256                                        Block::Code {
3257                                            has_preceding_blank, ..
3258                                        } => *has_preceding_blank,
3259                                        Block::Html {
3260                                            has_preceding_blank, ..
3261                                        } => *has_preceding_blank,
3262                                        Block::Table {
3263                                            has_preceding_blank, ..
3264                                        } => *has_preceding_blank,
3265                                        Block::SnippetLine(_) | Block::DivMarker(_) => false,
3266                                        _ => true,
3267                                    };
3268                                    if should_add_blank && result.last().is_none_or(|s: &String| !s.is_empty()) {
3269                                        result.push(String::new());
3270                                    }
3271                                }
3272                            }
3273                            Block::Admonition {
3274                                header,
3275                                header_indent,
3276                                content_lines: admon_lines,
3277                            } => {
3278                                // Reconstruct admonition block with header at original indent
3279                                // and body content reflowed to fit within the line length limit
3280
3281                                // Add blank line before admonition if not first block
3282                                if !is_first_block && result.last().is_none_or(|s: &String| !s.is_empty()) {
3283                                    result.push(String::new());
3284                                }
3285
3286                                // Output the header at its original indent
3287                                let header_indent_str = " ".repeat(*header_indent);
3288                                if is_first_block {
3289                                    result.push(format!(
3290                                        "{marker}{}",
3291                                        " ".repeat(header_indent.saturating_sub(marker_len)) + header.as_str()
3292                                    ));
3293                                    is_first_block = false;
3294                                } else {
3295                                    result.push(format!("{header_indent_str}{header}"));
3296                                }
3297
3298                                // Derive body indent from the first non-empty content line's
3299                                // stored indent, falling back to header_indent + 4 for
3300                                // empty-body admonitions
3301                                let body_indent = admon_lines
3302                                    .iter()
3303                                    .find(|(content, _)| !content.is_empty())
3304                                    .map_or(header_indent + 4, |(_, indent)| *indent);
3305                                let body_indent_str = " ".repeat(body_indent);
3306
3307                                // Segment body content into code blocks (verbatim) and
3308                                // text paragraphs (reflowable), separated by blank lines.
3309                                // Code lines store (content, orig_indent) to reconstruct
3310                                // internal indentation relative to body_indent.
3311                                enum AdmonSegment {
3312                                    Text(Vec<String>),
3313                                    Code(Vec<(String, usize)>),
3314                                }
3315
3316                                let mut segments: Vec<AdmonSegment> = Vec::new();
3317                                let mut current_text: Vec<String> = Vec::new();
3318                                let mut current_code: Vec<(String, usize)> = Vec::new();
3319                                let mut in_admon_code = false;
3320                                // Track the opening fence character so closing fences
3321                                // must match (backticks close backticks, tildes close tildes)
3322                                let mut fence_char: char = '`';
3323
3324                                // Opening fences: ``` or ~~~ followed by optional info string
3325                                let get_opening_fence = |s: &str| -> Option<(char, usize)> {
3326                                    let t = s.trim_start();
3327                                    if t.starts_with("```") {
3328                                        Some(('`', t.bytes().take_while(|&b| b == b'`').count()))
3329                                    } else if t.starts_with("~~~") {
3330                                        Some(('~', t.bytes().take_while(|&b| b == b'~').count()))
3331                                    } else {
3332                                        None
3333                                    }
3334                                };
3335                                // Closing fences: ONLY fence chars + optional trailing spaces
3336                                let get_closing_fence = |s: &str| -> Option<(char, usize)> {
3337                                    let t = s.trim();
3338                                    if t.starts_with("```") && t.bytes().all(|b| b == b'`') {
3339                                        Some(('`', t.len()))
3340                                    } else if t.starts_with("~~~") && t.bytes().all(|b| b == b'~') {
3341                                        Some(('~', t.len()))
3342                                    } else {
3343                                        None
3344                                    }
3345                                };
3346                                let mut fence_len: usize = 3;
3347
3348                                for (content, orig_indent) in admon_lines {
3349                                    if in_admon_code {
3350                                        // Closing fence must use the same character, be
3351                                        // at least as long, and have no info string
3352                                        if let Some((ch, len)) = get_closing_fence(content)
3353                                            && ch == fence_char
3354                                            && len >= fence_len
3355                                        {
3356                                            current_code.push((content.clone(), *orig_indent));
3357                                            in_admon_code = false;
3358                                            segments.push(AdmonSegment::Code(std::mem::take(&mut current_code)));
3359                                            continue;
3360                                        }
3361                                        current_code.push((content.clone(), *orig_indent));
3362                                    } else if let Some((ch, len)) = get_opening_fence(content) {
3363                                        if !current_text.is_empty() {
3364                                            segments.push(AdmonSegment::Text(std::mem::take(&mut current_text)));
3365                                        }
3366                                        in_admon_code = true;
3367                                        fence_char = ch;
3368                                        fence_len = len;
3369                                        current_code.push((content.clone(), *orig_indent));
3370                                    } else if content.is_empty() {
3371                                        if !current_text.is_empty() {
3372                                            segments.push(AdmonSegment::Text(std::mem::take(&mut current_text)));
3373                                        }
3374                                    } else {
3375                                        current_text.push(content.clone());
3376                                    }
3377                                }
3378                                if in_admon_code && !current_code.is_empty() {
3379                                    segments.push(AdmonSegment::Code(std::mem::take(&mut current_code)));
3380                                }
3381                                if !current_text.is_empty() {
3382                                    segments.push(AdmonSegment::Text(std::mem::take(&mut current_text)));
3383                                }
3384
3385                                // Build reflow options once for all text segments
3386                                let admon_reflow_length = if config.line_length.is_unlimited() {
3387                                    usize::MAX
3388                                } else {
3389                                    config.line_length.get().saturating_sub(body_indent).max(1)
3390                                };
3391
3392                                let admon_reflow_options = Self::reflow_options(ctx, config, admon_reflow_length);
3393
3394                                // Output each segment
3395                                for segment in &segments {
3396                                    // Blank line before each segment (after the header or previous segment)
3397                                    result.push(String::new());
3398
3399                                    match segment {
3400                                        AdmonSegment::Code(lines) => {
3401                                            for (line, orig_indent) in lines {
3402                                                if line.is_empty() {
3403                                                    // Preserve blank lines inside code blocks
3404                                                    result.push(String::new());
3405                                                } else {
3406                                                    // Reconstruct with body_indent + any extra
3407                                                    // indentation the line had beyond body_indent
3408                                                    let extra = orig_indent.saturating_sub(body_indent);
3409                                                    let indent_str = " ".repeat(body_indent + extra);
3410                                                    result.push(format!("{indent_str}{line}"));
3411                                                }
3412                                            }
3413                                        }
3414                                        AdmonSegment::Text(lines) => {
3415                                            let paragraph_text = lines.join(" ").trim().to_string();
3416                                            if paragraph_text.is_empty() {
3417                                                continue;
3418                                            }
3419                                            let reflowed = crate::utils::text_reflow::reflow_line(
3420                                                &paragraph_text,
3421                                                &admon_reflow_options,
3422                                            );
3423                                            for line in &reflowed {
3424                                                result.push(format!("{body_indent_str}{line}"));
3425                                            }
3426                                        }
3427                                    }
3428                                }
3429
3430                                // Add blank line after admonition if there's a next block
3431                                if block_idx < blocks.len() - 1 {
3432                                    let next_block = &blocks[block_idx + 1];
3433                                    let should_add_blank = match next_block {
3434                                        Block::Code {
3435                                            has_preceding_blank, ..
3436                                        } => *has_preceding_blank,
3437                                        Block::Table {
3438                                            has_preceding_blank, ..
3439                                        } => *has_preceding_blank,
3440                                        Block::SnippetLine(_) | Block::DivMarker(_) => false,
3441                                        _ => true,
3442                                    };
3443                                    if should_add_blank && result.last().is_none_or(|s: &String| !s.is_empty()) {
3444                                        result.push(String::new());
3445                                    }
3446                                }
3447                            }
3448                        }
3449                    }
3450
3451                    let reflowed_text = result.join(line_ending);
3452
3453                    // Preserve trailing newline
3454                    let replacement = if end_line < lines.len() - 1 || ctx.content.ends_with('\n') {
3455                        format!("{reflowed_text}{line_ending}")
3456                    } else {
3457                        reflowed_text
3458                    };
3459
3460                    // Get the original text to compare
3461                    let original_text = &ctx.content[byte_range.clone()];
3462
3463                    // Physical-line-length scan, shared by the Normalize-mode gate and its
3464                    // message. The list-item reflow preserves code blocks, HTML blocks,
3465                    // admonition headers, fence markers, semantic markers, and snippet/div
3466                    // markers verbatim; only paragraph content and admonition bodies are
3467                    // restructured. Only those lines drive the length warning, so that
3468                    // preserved-but-overlong content does not keep the paragraph-level
3469                    // warning alive when the reflow would not fix that line.
3470                    let should_count_for_length = |line_idx: usize| -> bool {
3471                        let line = lines[line_idx];
3472                        let trimmed = line.trim();
3473                        if trimmed.is_empty() || is_exempt_line(line, line_idx + 1) {
3474                            return false;
3475                        }
3476                        let info = &ctx.lines[line_idx];
3477                        if info.in_code_block || info.in_html_block {
3478                            return false;
3479                        }
3480                        if info.in_admonition && mkdocs_admonitions::is_admonition_start(line) {
3481                            return false;
3482                        }
3483                        if is_fence_marker(line) || is_semantic_line(line) {
3484                            return false;
3485                        }
3486                        if is_snippet_block_delimiter(line) {
3487                            return false;
3488                        }
3489                        if line.trim_start().starts_with(":::") {
3490                            return false;
3491                        }
3492                        true
3493                    };
3494                    let max_physical_length = (list_start..i)
3495                        .filter(|&idx| should_count_for_length(idx))
3496                        .map(|idx| self.calculate_effective_length(lines[idx]))
3497                        .max()
3498                        .unwrap_or(0);
3499                    // `line-length = 0` means "no limit", so no physical line can be
3500                    // "over"; the message below then describes a structural join rather
3501                    // than a length violation.
3502                    let any_paragraph_line_over =
3503                        !config.line_length.is_unlimited() && max_physical_length > config.line_length.get();
3504
3505                    // Normalize mode reflows list-item prose just like paragraphs:
3506                    // joining continuation lines and re-wrapping to `line-length`.
3507                    // `prose_changed` is true only when the reflow alters the words or
3508                    // line breaks, not when it would merely re-indent continuation
3509                    // lines or trim trailing whitespace. Comparing the texts with each
3510                    // line's leading and trailing whitespace removed isolates "did the
3511                    // words/line breaks change" from "did the surrounding whitespace
3512                    // change". Continuation indentation is MD077's responsibility and
3513                    // trailing whitespace is MD009's; an MD013 warning for either would
3514                    // both duplicate those rules and resurface a persistent advisory on
3515                    // already-fitting items that users disable MD013 fixing to avoid.
3516                    let prose_changed = {
3517                        let stripped = |text: &str| text.lines().map(str::trim).collect::<Vec<_>>().join("\n");
3518                        stripped(original_text) != stripped(&replacement)
3519                    };
3520                    // Warn when the reflow rewraps prose (the normalize feature for
3521                    // list items), or when a physical line genuinely exceeds the limit
3522                    // and the reflow can change something (a true length violation,
3523                    // even if all that changes is the continuation indent). A line that
3524                    // is already optimal in both respects produces no warning.
3525                    let gate_ok = prose_changed || (any_paragraph_line_over && original_text != replacement);
3526                    if gate_ok {
3527                        // Generate an appropriate message based on why reflow is needed
3528                        let message = match config.reflow_mode {
3529                            ReflowMode::SentencePerLine => {
3530                                let num_sentences = split_into_sentences(
3531                                    &combined_content,
3532                                    Some(&defined_references),
3533                                    config.require_sentence_capital,
3534                                )
3535                                .len();
3536                                let num_lines = content_lines.len();
3537                                if num_lines == 1 {
3538                                    // Single line with multiple sentences
3539                                    format!("Line contains {num_sentences} sentences (one sentence per line required)")
3540                                } else {
3541                                    // Multiple lines - could be split sentences or mixed
3542                                    format!(
3543                                        "Paragraph should have one sentence per line (found {num_sentences} sentences across {num_lines} lines)"
3544                                    )
3545                                }
3546                            }
3547                            ReflowMode::SemanticLineBreaks => {
3548                                let num_sentences = split_into_sentences(
3549                                    &combined_content,
3550                                    Some(&defined_references),
3551                                    config.require_sentence_capital,
3552                                )
3553                                .len();
3554                                format!("Paragraph should use semantic line breaks ({num_sentences} sentences)")
3555                            }
3556                            ReflowMode::Normalize => {
3557                                // When a physical line genuinely exceeds the limit, report
3558                                // it as a length violation. Otherwise the reflow is a
3559                                // structural normalization (joining/re-wrapping multi-line
3560                                // content that already fits), mirroring the paragraph path.
3561                                if any_paragraph_line_over {
3562                                    format!(
3563                                        "Line length {} exceeds {} characters",
3564                                        max_physical_length,
3565                                        config.line_length.get()
3566                                    )
3567                                } else {
3568                                    format!(
3569                                        "List item could be normalized to use line length of {} characters",
3570                                        config.line_length.get()
3571                                    )
3572                                }
3573                            }
3574                            ReflowMode::Default => {
3575                                // Report the actual longest non-exempt line, not the combined content
3576                                let max_length = (list_start..i)
3577                                    .filter(|&line_idx| {
3578                                        let line = lines[line_idx];
3579                                        let trimmed = line.trim();
3580                                        !trimmed.is_empty() && !is_exempt_line(line, line_idx + 1)
3581                                    })
3582                                    .map(|line_idx| self.calculate_effective_length(lines[line_idx]))
3583                                    .max()
3584                                    .unwrap_or(0);
3585                                format!(
3586                                    "Line length {} exceeds {} characters",
3587                                    max_length,
3588                                    config.line_length.get()
3589                                )
3590                            }
3591                        };
3592
3593                        warnings.push(LintWarning {
3594                            rule_name: Some(self.name().to_string()),
3595                            message,
3596                            line: list_start + 1,
3597                            column: 1,
3598                            end_line: end_line + 1,
3599                            end_column: lines[end_line].chars().count() + 1,
3600                            severity: Severity::Warning,
3601                            fix: Some(crate::rule::Fix::new(byte_range, replacement)),
3602                        });
3603                    }
3604                }
3605                continue;
3606            }
3607
3608            // A definition list's lines are laid out by the list: a term is one
3609            // line of its own, and a definition's text sits at the column its
3610            // marker sets, so reflowing them as prose moves text out of the list.
3611            if ctx.is_in_definition_list(line_num) {
3612                i += 1;
3613                continue;
3614            }
3615
3616            // Found start of a paragraph - collect all lines in it
3617            let paragraph_start = i;
3618            let mut paragraph_lines = vec![lines[i]];
3619            i += 1;
3620
3621            while i < lines.len() {
3622                let next_line = lines[i];
3623                let next_line_num = i + 1;
3624                let next_trimmed = next_line.trim();
3625
3626                // Stop at paragraph boundaries
3627                if next_trimmed.is_empty()
3628                    || ctx.line_info(next_line_num).is_some_and(|info| info.in_code_block)
3629                    || ctx.line_info(next_line_num).is_some_and(|info| info.in_front_matter)
3630                    || ctx.line_info(next_line_num).is_some_and(|info| info.in_html_block)
3631                    || ctx.line_info(next_line_num).is_some_and(|info| info.in_html_comment)
3632                    || ctx.line_info(next_line_num).is_some_and(|info| info.in_esm_block)
3633                    || ctx.line_info(next_line_num).is_some_and(|info| info.in_jsx_expression)
3634                    || ctx.line_info(next_line_num).is_some_and(|info| info.in_jsx_block)
3635                    || ctx.line_info(next_line_num).is_some_and(|info| info.in_mdx_comment)
3636                    || ctx
3637                        .line_info(next_line_num)
3638                        .is_some_and(super::super::lint_context::types::LineInfo::in_mkdocs_container)
3639                    || (next_line_num > 0
3640                        && next_line_num <= ctx.lines.len()
3641                        && ctx.lines[next_line_num - 1].blockquote.is_some())
3642                    || next_trimmed.starts_with('#')
3643                    // A setext heading ends the paragraph before it. The flag is
3644                    // set on every line of the heading's text, so the paragraph
3645                    // stops at the first of them and absorbs no heading text.
3646                    // That also protects the underline, which can only follow the
3647                    // last text line, so absorbing the construct and joining it
3648                    // into prose is unreachable from here. `is_horizontal_rule`
3649                    // below catches a `---` underline only by coincidence (3+
3650                    // dashes are also a thematic break); `=` and short `-` runs
3651                    // have no such overlap.
3652                    || is_setext_heading_text_line(ctx, next_line_num)
3653                    || TableUtils::is_potential_table_row_with_flavor(next_line, ctx.flavor)
3654                    || is_list_item(next_trimmed)
3655                    || is_horizontal_rule(next_line)
3656                    || (next_trimmed.starts_with('[') && next_line.contains("]:"))
3657                    || is_template_directive_only(next_line)
3658                    || is_standalone_attr_list(next_line)
3659                    || is_snippet_block_delimiter(next_line)
3660                    || ctx.line_info(next_line_num).is_some_and(|info| info.is_div_marker)
3661                    || is_html_only_line(next_line)
3662                    || self.line_in_multiline_math_block(next_line_num, ctx, config)
3663                    // A line that is one whole `$$...$$` expression renders as a
3664                    // display block, so it ends the paragraph above it and is
3665                    // reflowed on its own. A line touched by a code span crossing
3666                    // one of its boundaries is code, not such a block.
3667                    || ((is_self_contained_display_math_line(next_line)
3668                        || self.line_is_standalone_bracket_math(next_line_num, ctx, config))
3669                        && !line_touches_multiline_code_span(&code_span_touches, next_line_num))
3670                    || standalone_link_ends_paragraph(ctx, next_line_num, config)
3671                {
3672                    break;
3673                }
3674
3675                // Check if the previous line ends with a hard break (2+ spaces or backslash)
3676                if i > 0 && has_hard_break(lines[i - 1]) {
3677                    // Don't include lines after hard breaks in the same paragraph
3678                    break;
3679                }
3680
3681                paragraph_lines.push(next_line);
3682                i += 1;
3683            }
3684
3685            // Compute the common leading indent of all non-empty paragraph lines,
3686            // but only when those lines are structurally inside a list block.
3687            // Indented continuation lines that follow a nested list arrive here
3688            // with their structural indentation intact (e.g. 2 spaces for a
3689            // top-level list item). Stripping the indent before reflow and
3690            // re-applying it afterward prevents the fixer from moving those
3691            // lines to column 0.
3692            //
3693            // The list-block guard is essential: top-level paragraphs that happen
3694            // to start with spaces (insignificant in Markdown) must NOT have those
3695            // spaces preserved or injected by the fixer.
3696            let common_indent: String = if ctx.is_in_list_block(paragraph_start + 1) {
3697                let min_len = paragraph_lines
3698                    .iter()
3699                    .filter(|l| !l.trim().is_empty())
3700                    .map(|l| l.len() - l.trim_start().len())
3701                    .min()
3702                    .unwrap_or(0);
3703                paragraph_lines
3704                    .iter()
3705                    .find(|l| !l.trim().is_empty())
3706                    .map(|l| l[..min_len].to_string())
3707                    .unwrap_or_default()
3708            } else {
3709                String::new()
3710            };
3711
3712            // Combine paragraph lines into a single string for processing.
3713            // This must be done BEFORE the needs_reflow check for sentence-per-line mode.
3714            let paragraph_text = if common_indent.is_empty() {
3715                join_soft_break_lines(&paragraph_lines)
3716            } else {
3717                let stripped: Vec<&str> = paragraph_lines
3718                    .iter()
3719                    .map(|l| {
3720                        if l.starts_with(common_indent.as_str()) {
3721                            &l[common_indent.len()..]
3722                        } else {
3723                            l.trim_start()
3724                        }
3725                    })
3726                    .collect();
3727                join_soft_break_lines(&stripped)
3728            };
3729
3730            // A colon-led line with a line of the paragraph before it opens a
3731            // definition, and joining the lines would flatten the definition
3732            // list into prose, so the paragraph is skipped. Its first line is
3733            // prose whatever it starts with, since a definition needs a term on
3734            // the line before it. The indentation a marker is allowed is
3735            // counted from the block's own content, so a list item's
3736            // indentation comes off first.
3737            let contains_definition_list = paragraph_lines.iter().skip(1).any(|line| {
3738                let content = line.strip_prefix(common_indent.as_str()).unwrap_or(line.trim_start());
3739                crate::utils::text_reflow::is_definition_list_marker(content)
3740            });
3741
3742            if contains_definition_list {
3743                // Don't reflow definition lists - skip this paragraph
3744                i = paragraph_start + paragraph_lines.len();
3745                continue;
3746            }
3747
3748            // Skip reflowing if this paragraph contains MkDocs Snippets markers
3749            // Snippets blocks (-8<- ... -8<-) should be preserved exactly
3750            let contains_snippets = paragraph_lines.iter().any(|line| is_snippet_block_delimiter(line));
3751
3752            if contains_snippets {
3753                // Don't reflow Snippets blocks - skip this paragraph
3754                i = paragraph_start + paragraph_lines.len();
3755                continue;
3756            }
3757
3758            // Leave a line of a multi-line display-math block as it is, where
3759            // joining lines would corrupt the equation (see
3760            // `line_in_multiline_math_block`). Only the first line has to be
3761            // asked about: such a line ends the paragraph above it, so a
3762            // paragraph reaching here holds one only when it starts on one.
3763            //
3764            // Only that line is passed over, not the rest of what was collected
3765            // with it: prose written directly under the closing delimiter is an
3766            // ordinary paragraph and still reflows.
3767            if self.line_in_multiline_math_block(paragraph_start + 1, ctx, config) {
3768                i = paragraph_start + 1;
3769                continue;
3770            }
3771
3772            // A line that is one whole `$$...$$` expression is a display block:
3773            // it keeps the line it was written on, and the prose under it is an
3774            // ordinary paragraph that still reflows. The line above ended at
3775            // this one, so a paragraph reaching here holds one only when it
3776            // starts on one. A paragraph can start on a line touched by a code
3777            // span crossing one of its boundaries, under a hard break the span
3778            // holds, and its first line is code then.
3779            if (is_self_contained_display_math_line(lines[paragraph_start])
3780                || self.line_is_standalone_bracket_math(paragraph_start + 1, ctx, config))
3781                && !line_touches_multiline_code_span(&code_span_touches, paragraph_start + 1)
3782            {
3783                i = paragraph_start + 1;
3784                continue;
3785            }
3786
3787            // Check if this paragraph needs reflowing
3788            let needs_reflow = match config.reflow_mode {
3789                ReflowMode::Normalize => self.normalize_mode_needs_reflow(paragraph_lines.iter().copied(), config),
3790                ReflowMode::SentencePerLine => {
3791                    // In sentence-per-line mode, check if the JOINED paragraph has multiple sentences
3792                    // Note: we check the joined text because sentences can span multiple lines
3793                    let sentences = split_into_sentences(
3794                        &paragraph_text,
3795                        Some(&defined_references),
3796                        config.require_sentence_capital,
3797                    );
3798
3799                    // Always reflow if multiple sentences on one line
3800                    if sentences.len() > 1 {
3801                        true
3802                    } else if paragraph_lines.len() > 1 {
3803                        // For single-sentence paragraphs spanning multiple lines:
3804                        // Reflow if they COULD fit on one line (respecting line-length constraint)
3805                        if config.line_length.is_unlimited() {
3806                            // No line-length constraint - always join single sentences
3807                            true
3808                        } else {
3809                            // Only join if it fits within line-length.
3810                            // paragraph_text has the common indent stripped, so add it
3811                            // back to get the true output length before comparing.
3812                            let effective_length =
3813                                self.calculate_effective_length(&paragraph_text) + common_indent.len();
3814                            effective_length <= config.line_length.get()
3815                        }
3816                    } else {
3817                        false
3818                    }
3819                }
3820                ReflowMode::SemanticLineBreaks => {
3821                    let sentences = split_into_sentences(
3822                        &paragraph_text,
3823                        Some(&defined_references),
3824                        config.require_sentence_capital,
3825                    );
3826                    // Reflow if multiple sentences, multiple lines, or any line exceeds limit
3827                    sentences.len() > 1
3828                        || paragraph_lines.len() > 1
3829                        || paragraph_lines
3830                            .iter()
3831                            .any(|line| self.calculate_effective_length(line) > config.line_length.get())
3832                }
3833                ReflowMode::Default => {
3834                    // In default mode, only reflow if lines exceed limit
3835                    paragraph_lines
3836                        .iter()
3837                        .any(|line| self.calculate_effective_length(line) > config.line_length.get())
3838                }
3839            };
3840
3841            if needs_reflow {
3842                // Calculate byte range for this paragraph
3843                // Use whole_line_range for each line and combine
3844                let start_range = ctx.whole_line_byte_range(paragraph_start + 1);
3845                let end_line = paragraph_start + paragraph_lines.len() - 1;
3846
3847                // For the last line, we want to preserve any trailing newline
3848                let end_range = if end_line == lines.len() - 1 && !ctx.content.ends_with('\n') {
3849                    // Last line without trailing newline - use line_text_range
3850                    ctx.line_text_byte_range(end_line + 1, 1, lines[end_line].len() + 1)
3851                } else {
3852                    // Not the last line or has trailing newline - use whole_line_range
3853                    ctx.whole_line_byte_range(end_line + 1)
3854                };
3855
3856                let byte_range = start_range.start..end_range.end;
3857
3858                // Check if the paragraph ends with a hard break and what type
3859                let hard_break_type = paragraph_lines.last().and_then(|line| {
3860                    let line = line.strip_suffix('\r').unwrap_or(line);
3861                    if line.ends_with('\\') {
3862                        Some("\\")
3863                    } else if line.ends_with("  ") {
3864                        Some("  ")
3865                    } else {
3866                        None
3867                    }
3868                });
3869
3870                // Reflow the paragraph
3871                // When line_length = 0 (no limit), use a very large value for reflow
3872                let reflow_line_length = if config.line_length.is_unlimited() {
3873                    usize::MAX
3874                } else {
3875                    config.line_length.get().saturating_sub(common_indent.len()).max(1)
3876                };
3877                let reflow_options = Self::reflow_options(ctx, config, reflow_line_length);
3878                let mut reflowed = crate::utils::text_reflow::reflow_line(&paragraph_text, &reflow_options);
3879
3880                // Re-apply the common indent to each non-empty reflowed line so
3881                // that the replacement preserves the original structural indentation.
3882                if !common_indent.is_empty() {
3883                    for line in &mut reflowed {
3884                        if !line.is_empty() {
3885                            *line = format!("{common_indent}{line}");
3886                        }
3887                    }
3888                }
3889
3890                // If the original paragraph ended with a hard break, preserve it
3891                // Preserve the original hard break format (backslash or two spaces)
3892                if let Some(break_marker) = hard_break_type
3893                    && !reflowed.is_empty()
3894                {
3895                    let last_idx = reflowed.len() - 1;
3896                    if !has_hard_break(&reflowed[last_idx]) {
3897                        reflowed[last_idx].push_str(break_marker);
3898                    }
3899                }
3900
3901                let reflowed_text = reflowed.join(line_ending);
3902
3903                // Preserve trailing newline if the original paragraph had one
3904                let replacement = if end_line < lines.len() - 1 || ctx.content.ends_with('\n') {
3905                    format!("{reflowed_text}{line_ending}")
3906                } else {
3907                    reflowed_text
3908                };
3909
3910                // Get the original text to compare
3911                let original_text = &ctx.content[byte_range.clone()];
3912
3913                // Only generate a warning if the replacement is different from the original
3914                if original_text != replacement {
3915                    // Determine which line ranges and messages to report based on the reflow mode.
3916                    let warnings_to_report: Vec<(usize, usize, String)> = match config.reflow_mode {
3917                        ReflowMode::Default => {
3918                            // In default mode, report a warning for *every* line in the paragraph
3919                            // that exceeds the limit. Each warning will carry the same paragraph-level
3920                            // fix, making all of them auto-fixable.
3921                            paragraph_lines
3922                                .iter()
3923                                .enumerate()
3924                                .filter(|(_, line)| self.calculate_effective_length(line) > config.line_length.get())
3925                                .map(|(idx, _)| {
3926                                    let violating_line = paragraph_start + idx + 1;
3927                                    (
3928                                        violating_line,
3929                                        violating_line,
3930                                        format!("Line length exceeds {} characters", config.line_length.get()),
3931                                    )
3932                                })
3933                                .collect()
3934                        }
3935                        ReflowMode::Normalize => {
3936                            // In normalize mode, report the whole paragraph as needing normalization.
3937                            vec![(
3938                                paragraph_start + 1,
3939                                end_line + 1,
3940                                format!(
3941                                    "Paragraph could be normalized to use line length of {} characters",
3942                                    config.line_length.get()
3943                                ),
3944                            )]
3945                        }
3946                        ReflowMode::SentencePerLine => {
3947                            // In sentence-per-line mode, highlight the entire paragraph that needs reformatting.
3948                            let num_sentences = split_into_sentences(
3949                                &paragraph_text,
3950                                Some(&defined_references),
3951                                config.require_sentence_capital,
3952                            )
3953                            .len();
3954                            let message = if paragraph_lines.len() == 1 {
3955                                // Single line with multiple sentences
3956                                format!("Line contains {num_sentences} sentences (one sentence per line required)")
3957                            } else {
3958                                // Multiple lines - could be split sentences or mixed
3959                                let num_lines = paragraph_lines.len();
3960                                format!(
3961                                    "Paragraph should have one sentence per line (found {num_sentences} sentences across {num_lines} lines)"
3962                                )
3963                            };
3964                            vec![(paragraph_start + 1, paragraph_start + paragraph_lines.len(), message)]
3965                        }
3966                        ReflowMode::SemanticLineBreaks => {
3967                            // In semantic-line-breaks mode, highlight the entire paragraph.
3968                            let num_sentences = split_into_sentences(
3969                                &paragraph_text,
3970                                Some(&defined_references),
3971                                config.require_sentence_capital,
3972                            )
3973                            .len();
3974                            vec![(
3975                                paragraph_start + 1,
3976                                paragraph_start + paragraph_lines.len(),
3977                                format!("Paragraph should use semantic line breaks ({num_sentences} sentences)"),
3978                            )]
3979                        }
3980                    };
3981
3982                    // Generate the actual lint warnings. All warnings for this paragraph
3983                    // share the same paragraph-level fix.
3984                    for (w_start, w_end, msg) in warnings_to_report {
3985                        warnings.push(LintWarning {
3986                            rule_name: Some(self.name().to_string()),
3987                            message: msg,
3988                            line: w_start,
3989                            column: 1,
3990                            end_line: w_end,
3991                            end_column: lines[w_end.saturating_sub(1)].chars().count() + 1,
3992                            severity: Severity::Warning,
3993                            fix: Some(crate::rule::Fix::new(byte_range.clone(), replacement.clone())),
3994                        });
3995                    }
3996                }
3997            }
3998        }
3999
4000        warnings
4001    }
4002
4003    /// Calculate string length based on the configured length mode
4004    fn calculate_string_length(&self, s: &str) -> usize {
4005        match self.config.length_mode {
4006            LengthMode::Chars => s.chars().count(),
4007            LengthMode::Visual => s.width(),
4008            LengthMode::Bytes => s.len(),
4009        }
4010    }
4011
4012    /// Calculate effective line length
4013    ///
4014    /// Returns the actual display length of the line using the configured length mode.
4015    fn calculate_effective_length(&self, line: &str) -> usize {
4016        self.calculate_string_length(line)
4017    }
4018
4019    /// Calculate line length with inline link/image URLs removed.
4020    ///
4021    /// For each inline link `[text](url)` or image `![alt](url)` on the line,
4022    /// computes the "savings" from removing the URL portion (keeping only `[text]`
4023    /// or `![alt]`). Returns `effective_length - total_savings`.
4024    ///
4025    /// Handles nested constructs (e.g., `[![img](url)](url)`) by only counting the
4026    /// outermost construct to avoid double-counting.
4027    fn length_without_inline_link_urls(
4028        &self,
4029        effective_length: usize,
4030        line_number: usize,
4031        ctx: &crate::lint_context::LintContext,
4032    ) -> usize {
4033        let line_range = ctx.line_content_byte_range(line_number);
4034        let line_byte_end = line_range.end;
4035
4036        // Collect inline links/images on this line: (byte_offset, byte_end, text_only_display_len)
4037        let mut constructs: Vec<(usize, usize, usize)> = Vec::new();
4038
4039        for link in ctx.links_on_line(line_number) {
4040            if link.is_reference {
4041                continue;
4042            }
4043            if !matches!(link.link_type, LinkType::Inline) {
4044                continue;
4045            }
4046            if link.byte_end > line_byte_end {
4047                continue;
4048            }
4049            let text_only_len = 2 + self.calculate_string_length(&link.text);
4050            constructs.push((link.byte_offset, link.byte_end, text_only_len));
4051        }
4052
4053        for image in ctx.images_on_line(line_number) {
4054            if image.is_reference {
4055                continue;
4056            }
4057            if !matches!(image.link_type, LinkType::Inline) {
4058                continue;
4059            }
4060            if image.byte_end > line_byte_end {
4061                continue;
4062            }
4063            let text_only_len = 3 + self.calculate_string_length(&image.alt_text);
4064            constructs.push((image.byte_offset, image.byte_end, text_only_len));
4065        }
4066
4067        if constructs.is_empty() {
4068            return effective_length;
4069        }
4070
4071        // Sort by byte offset to handle overlapping/nested constructs
4072        constructs.sort_by_key(|&(start, _, _)| start);
4073
4074        let mut total_savings: usize = 0;
4075        let mut last_end: usize = 0;
4076
4077        for (start, end, text_only_len) in &constructs {
4078            // Skip constructs nested inside a previously counted one
4079            if *start < last_end {
4080                continue;
4081            }
4082            // Full construct length in configured length mode
4083            let full_source = &ctx.content[*start..*end];
4084            let full_len = self.calculate_string_length(full_source);
4085            total_savings += full_len.saturating_sub(*text_only_len);
4086            last_end = *end;
4087        }
4088
4089        effective_length.saturating_sub(total_savings)
4090    }
4091}