aft/bash_rewrite/

rules.rs

use serde_json::{json, Value};
use std::path::{Path, PathBuf};
use std::time::{Duration, SystemTime};

const REGEX_SIZE_LIMIT: usize = 10 * 1024 * 1024;
const GREP_FOOTER_FRESHNESS_WINDOW: Duration = Duration::from_secs(60);

use crate::bash_rewrite::footer::{add_footer, add_grep_footer};
use crate::bash_rewrite::parser::parse;
use crate::bash_rewrite::{RewriteRequest, RewriteRule};
use crate::context::AppContext;
use crate::protocol::{RawRequest, Response};

pub struct GrepRule;
pub struct RgRule;
pub struct FindRule;
pub struct CatRule;
pub struct HeadRule;
pub struct TailRule;
pub struct CatAppendRule;
pub struct SedRule;
pub struct LsRule;

impl RewriteRule for GrepRule {
    fn name(&self) -> &'static str {
        "grep"
    }

    fn decide(
        &self,
        command: &str,
        request_id: &str,
        session_id: Option<&str>,
        ctx: &AppContext,
    ) -> crate::bash_rewrite::RewriteDecision {
        let Some(params) = grep_request(command, "grep") else {
            return decline("grep", "grep.decline", "unsupported grep shape");
        };
        if let Some(path) = params.get("path").and_then(Value::as_str) {
            if !path_is_safe(ctx, path, true) {
                return decline(
                    "grep",
                    "grep.decline",
                    "grep path is outside the project root or missing",
                );
            }
        }
        accept(
            "grep",
            "grep.accept",
            "dc.grep.accept.v1",
            command,
            request_id,
            session_id,
            params,
        )
    }

    fn execute(&self, request: &RewriteRequest, ctx: &AppContext) -> Response {
        let path = request.params.get("path").and_then(Value::as_str);
        let response = crate::commands::grep::handle_grep(&tool_request("grep", request, ctx), ctx);
        grep_footer_response(response, ctx, path)
    }
}

impl RewriteRule for RgRule {
    fn name(&self) -> &'static str {
        "rg"
    }

    fn decide(
        &self,
        command: &str,
        request_id: &str,
        session_id: Option<&str>,
        ctx: &AppContext,
    ) -> crate::bash_rewrite::RewriteDecision {
        let Some(params) = grep_request(command, "rg") else {
            return decline("rg", "rg.decline", "unsupported rg shape");
        };
        if let Some(path) = params.get("path").and_then(Value::as_str) {
            if !path_is_safe(ctx, path, true) {
                return decline(
                    "rg",
                    "rg.decline",
                    "rg path is outside the project root or missing",
                );
            }
        }
        accept(
            "rg",
            "rg.accept",
            "dc.rg.accept.v1",
            command,
            request_id,
            session_id,
            params,
        )
    }

    fn execute(&self, request: &RewriteRequest, ctx: &AppContext) -> Response {
        let path = request.params.get("path").and_then(Value::as_str);
        let response = crate::commands::grep::handle_grep(&tool_request("grep", request, ctx), ctx);
        grep_footer_response(response, ctx, path)
    }
}

impl RewriteRule for FindRule {
    fn name(&self) -> &'static str {
        "find"
    }

    fn decide(
        &self,
        command: &str,
        request_id: &str,
        session_id: Option<&str>,
        ctx: &AppContext,
    ) -> crate::bash_rewrite::RewriteDecision {
        let Some(params) = find_request(command) else {
            return decline("find", "find.decline", "unsupported find shape");
        };
        if let Some(path) = params.get("path").and_then(Value::as_str) {
            if !path_is_safe(ctx, path, true) {
                return decline(
                    "find",
                    "find.decline",
                    "find path is outside the project root or missing",
                );
            }
        }
        accept(
            "find",
            "find.accept",
            "dc.find.accept.v1",
            command,
            request_id,
            session_id,
            params,
        )
    }

    fn execute(&self, request: &RewriteRequest, ctx: &AppContext) -> Response {
        call_and_footer(
            crate::commands::glob::handle_glob(&tool_request("glob", request, ctx), ctx),
            "glob",
        )
    }
}

impl RewriteRule for CatRule {
    fn name(&self) -> &'static str {
        "cat"
    }

    fn decide(
        &self,
        command: &str,
        request_id: &str,
        session_id: Option<&str>,
        ctx: &AppContext,
    ) -> crate::bash_rewrite::RewriteDecision {
        let Some(params) = cat_read_request(command) else {
            return decline("cat", "cat.decline", "unsupported cat shape");
        };
        let path = params
            .get("file")
            .and_then(Value::as_str)
            .unwrap_or_default();
        if !path_is_safe(ctx, path, true) {
            return decline_cat_read(ctx, path, "path_is_safe");
        }
        if !read_shape_is_faithful(ctx, path) {
            return decline_cat_read(ctx, path, "read_shape_is_faithful");
        }
        accept(
            "cat",
            "cat.accept",
            "dc.cat.accept.v1",
            command,
            request_id,
            session_id,
            params,
        )
    }

    fn execute(&self, request: &RewriteRequest, ctx: &AppContext) -> Response {
        call_and_footer(
            crate::commands::read::handle_read(&tool_request("read", request, ctx), ctx),
            "read",
        )
    }
}

impl RewriteRule for HeadRule {
    fn name(&self) -> &'static str {
        "head"
    }

    fn decide(
        &self,
        command: &str,
        request_id: &str,
        session_id: Option<&str>,
        ctx: &AppContext,
    ) -> crate::bash_rewrite::RewriteDecision {
        let Some(params) = head_tail_read_request(command, "head") else {
            return decline("head", "head.decline", "unsupported head shape");
        };
        let path = params
            .get("file")
            .and_then(Value::as_str)
            .unwrap_or_default();
        let lines = params.get("limit").and_then(Value::as_u64).unwrap_or(10) as usize;
        if !effective_hashline_session(ctx, session_id)
            || !path_is_safe(ctx, path, true)
            || !head_tail_shape_is_faithful(ctx, path, lines, false)
        {
            return decline(
                "head",
                "head.decline",
                "head requires an effective hashline session and a faithful text-read shape",
            );
        }
        accept(
            "head",
            "head.accept",
            "dc.head.accept.v1",
            command,
            request_id,
            session_id,
            params,
        )
    }

    fn execute(&self, request: &RewriteRequest, ctx: &AppContext) -> Response {
        call_and_footer(
            crate::commands::read::handle_read(&tool_request("read", request, ctx), ctx),
            "read",
        )
    }
}

impl RewriteRule for TailRule {
    fn name(&self) -> &'static str {
        "tail"
    }

    fn decide(
        &self,
        command: &str,
        request_id: &str,
        session_id: Option<&str>,
        ctx: &AppContext,
    ) -> crate::bash_rewrite::RewriteDecision {
        let Some(params) = head_tail_read_request(command, "tail") else {
            return decline("tail", "tail.decline", "unsupported tail shape");
        };
        let path = params
            .get("file")
            .and_then(Value::as_str)
            .unwrap_or_default();
        let lines = params.get("limit").and_then(Value::as_u64).unwrap_or(10) as usize;
        if !effective_hashline_session(ctx, session_id)
            || !path_is_safe(ctx, path, true)
            || !head_tail_shape_is_faithful(ctx, path, lines, true)
        {
            return decline(
                "tail",
                "tail.decline",
                "tail requires an effective hashline session and a faithful text-read shape",
            );
        }
        accept(
            "tail",
            "tail.accept",
            "dc.tail.accept.v1",
            command,
            request_id,
            session_id,
            params,
        )
    }

    fn execute(&self, request: &RewriteRequest, ctx: &AppContext) -> Response {
        call_and_footer(
            crate::commands::read::handle_read(&tool_request("read", request, ctx), ctx),
            "read",
        )
    }
}

impl RewriteRule for CatAppendRule {
    fn name(&self) -> &'static str {
        "cat_append"
    }

    fn decide(
        &self,
        command: &str,
        request_id: &str,
        session_id: Option<&str>,
        ctx: &AppContext,
    ) -> crate::bash_rewrite::RewriteDecision {
        let Some(params) = append_request(command) else {
            return decline(
                "cat_append",
                "cat_append.decline",
                "unsupported append shape",
            );
        };
        let path = params
            .get("file")
            .and_then(Value::as_str)
            .unwrap_or_default();
        if !append_path_is_safe(ctx, path) {
            return decline(
                "cat_append",
                "cat_append.decline",
                "append path is outside the project root or has no existing parent",
            );
        }
        accept(
            "cat_append",
            "cat_append.accept",
            "dc.cat_append.accept.v1",
            command,
            request_id,
            session_id,
            params,
        )
    }

    fn execute(&self, request: &RewriteRequest, ctx: &AppContext) -> Response {
        call_and_footer(
            crate::commands::edit_match::handle_edit_match(
                &tool_request("edit_match", request, ctx),
                ctx,
            ),
            "edit",
        )
    }
}

impl RewriteRule for SedRule {
    fn name(&self) -> &'static str {
        "sed"
    }

    fn decide(
        &self,
        command: &str,
        request_id: &str,
        session_id: Option<&str>,
        ctx: &AppContext,
    ) -> crate::bash_rewrite::RewriteDecision {
        let Some(params) = sed_request(command) else {
            return decline("sed", "sed.decline", "unsupported sed shape");
        };
        let path = params
            .get("file")
            .and_then(Value::as_str)
            .unwrap_or_default();
        if !path_is_safe(ctx, path, true) || !read_shape_is_faithful(ctx, path) {
            return decline(
                "sed",
                "sed.decline",
                "sed path is outside the project root or exceeds the read contract",
            );
        }
        accept(
            "sed",
            "sed.accept",
            "dc.sed.accept.v1",
            command,
            request_id,
            session_id,
            params,
        )
    }

    fn execute(&self, request: &RewriteRequest, ctx: &AppContext) -> Response {
        call_and_footer(
            crate::commands::read::handle_read(&tool_request("read", request, ctx), ctx),
            "read",
        )
    }
}

impl RewriteRule for LsRule {
    fn name(&self) -> &'static str {
        "ls"
    }

    fn decide(
        &self,
        command: &str,
        request_id: &str,
        session_id: Option<&str>,
        ctx: &AppContext,
    ) -> crate::bash_rewrite::RewriteDecision {
        let Some(params) = ls_request(command, ctx) else {
            return decline("ls", "ls.decline", "unsupported ls shape or target");
        };
        accept(
            "ls",
            "ls.accept",
            "dc.ls.accept.v1",
            command,
            request_id,
            session_id,
            params,
        )
    }

    fn execute(&self, request: &RewriteRequest, ctx: &AppContext) -> Response {
        call_and_footer(
            crate::commands::read::handle_read(&tool_request("read", request, ctx), ctx),
            "read",
        )
    }
}

fn accept(
    rule_id: &'static str,
    branch_id: &'static str,
    decision_class_id: &'static str,
    command: &str,
    request_id: &str,
    session_id: Option<&str>,
    params: Value,
) -> crate::bash_rewrite::RewriteDecision {
    crate::bash_rewrite::RewriteDecision::Accept(RewriteRequest {
        request_id: request_id.to_string(),
        command: command.to_string(),
        session_id: session_id.map(str::to_owned),
        rule_id,
        branch_id,
        decision_class_id,
        params,
    })
}

fn decline(
    rule_id: &'static str,
    branch_id: &'static str,
    reason: &str,
) -> crate::bash_rewrite::RewriteDecision {
    let decision_class_id = match rule_id {
        "grep" => "dc.grep.decline.v1",
        "rg" => "dc.rg.decline.v1",
        "find" => "dc.find.decline.v1",
        "cat" => "dc.cat.decline.v1",
        "head" => "dc.head.decline.v1",
        "tail" => "dc.tail.decline.v1",
        "cat_append" => "dc.cat_append.decline.v1",
        "sed" => "dc.sed.decline.v1",
        "ls" => "dc.ls.decline.v1",
        _ => "dc.native.decline.v1",
    };
    crate::bash_rewrite::RewriteDecision::Decline(crate::bash_rewrite::DeclineReason {
        rule_id: Some(rule_id),
        branch_id,
        decision_class_id,
        reason: reason.to_string(),
    })
}

fn tool_request(tool: &str, request: &RewriteRequest, ctx: &AppContext) -> RawRequest {
    let mut params = request.params.clone();
    let root = grep_project_root(ctx);
    if matches!(tool, "read" | "edit_match") {
        if let Some(file) = params
            .get("file")
            .and_then(Value::as_str)
            .map(str::to_owned)
        {
            if tool == "read" && matches!(request.rule_id, "cat" | "head" | "tail") {
                params["_hashline_requested_path"] = Value::String(file.clone());
                params["_hashline_bash_read_kind"] = Value::String(request.rule_id.to_string());
                if let Some(lines) = request.params.get("limit").and_then(Value::as_u64) {
                    params["_hashline_bash_read_lines"] = Value::from(lines);
                }
            }
            let path = Path::new(&file);
            if path.is_relative() {
                params["file"] = Value::String(root.join(path).display().to_string());
            }
            if tool == "read" && request.rule_id == "tail" {
                if let Some(path) = params.get("file").and_then(Value::as_str) {
                    if let Some(total_lines) = text_file_line_count(Path::new(path)) {
                        if total_lines > 0 {
                            let lines = request
                                .params
                                .get("limit")
                                .and_then(Value::as_u64)
                                .unwrap_or(10) as usize;
                            params["start_line"] =
                                Value::from(total_lines.saturating_sub(lines).saturating_add(1));
                            params["end_line"] = Value::from(total_lines);
                        }
                    }
                }
            }
        }
    }
    if tool == "glob" && params.get("path").is_none() {
        params["path"] = Value::String(root.display().to_string());
    }
    RawRequest {
        id: request.request_id.clone(),
        command: tool.to_string(),
        lsp_hints: None,
        session_id: request.session_id.clone(),
        params,
    }
}

/// Add the normal tool footer while preserving a handler error as the final
/// response. A handler error is not a permission to execute native bash: the
/// request has already entered the internal handler.
fn call_and_footer(response: Response, replacement_tool: &str) -> Response {
    let output = response_output(&response.data);
    let footered = add_footer(&output, replacement_tool);
    apply_footer(response, footered)
}

fn grep_footer_response(response: Response, ctx: &AppContext, path: Option<&str>) -> Response {
    let output = response_output(&response.data);
    let footered = if should_suppress_grep_footer(path, &grep_project_root(ctx)) {
        output
    } else {
        add_grep_footer(&output, ctx.config().aft_search_registered)
    };
    apply_footer(response, footered)
}

fn grep_project_root(ctx: &AppContext) -> std::path::PathBuf {
    let configured = ctx
        .config()
        .project_root
        .clone()
        .unwrap_or_else(|| std::env::current_dir().unwrap_or_default());
    std::fs::canonicalize(&configured).unwrap_or(configured)
}

fn should_suppress_grep_footer(path: Option<&str>, project_root: &Path) -> bool {
    let Some(path) = path else {
        return false;
    };
    // Canonicalize the root here rather than trusting callers: the target
    // below is canonicalized, and comparing a canonical target against a
    // non-canonical root breaks on alias spellings (macOS /var vs
    // /private/var), misreading in-root paths as external.
    let project_root =
        std::fs::canonicalize(project_root).unwrap_or_else(|_| project_root.to_path_buf());
    let project_root = project_root.as_path();
    let target = Path::new(path);
    let target = if target.is_absolute() {
        target.to_path_buf()
    } else {
        project_root.join(target)
    };
    let Ok(target) = std::fs::canonicalize(target) else {
        return false;
    };
    if !target.starts_with(project_root) {
        return true;
    }
    let Ok(metadata) = std::fs::metadata(&target) else {
        return false;
    };
    if metadata.is_file() {
        return true;
    }
    let Ok(modified) = metadata.modified() else {
        return false;
    };
    SystemTime::now()
        .duration_since(modified)
        .is_ok_and(|age| age < GREP_FOOTER_FRESHNESS_WINDOW)
}

fn apply_footer(mut response: Response, output: String) -> Response {
    if let Some(object) = response.data.as_object_mut() {
        object.insert("output".to_string(), Value::String(output.clone()));

        for key in ["text", "content", "message"] {
            if object.get(key).is_some_and(Value::is_string) {
                object.insert(key.to_string(), Value::String(output.clone()));
                break;
            }
        }
    } else {
        response.data = json!({ "output": output });
    }

    response
}

fn response_output(data: &Value) -> String {
    if let Some(output) = data.get("output").and_then(Value::as_str) {
        return output.to_string();
    }
    if let Some(text) = data.get("text").and_then(Value::as_str) {
        return text.to_string();
    }
    if let Some(content) = data.get("content").and_then(Value::as_str) {
        return content.to_string();
    }
    if let Some(message) = data.get("message").and_then(Value::as_str) {
        return message.to_string();
    }
    if let Some(entries) = data.get("entries").and_then(Value::as_array) {
        return entries
            .iter()
            .filter_map(Value::as_str)
            .collect::<Vec<_>>()
            .join("\n");
    }
    serde_json::to_string_pretty(data).unwrap_or_else(|_| data.to_string())
}

fn path_candidate(ctx: &AppContext, path: &str) -> PathBuf {
    let candidate = Path::new(path);
    if candidate.is_absolute() {
        candidate.to_path_buf()
    } else {
        grep_project_root(ctx).join(candidate)
    }
}

fn resolved_path_candidate(ctx: &AppContext, path: &str) -> PathBuf {
    let candidate = path_candidate(ctx, path);
    std::fs::canonicalize(&candidate).unwrap_or(candidate)
}

fn decline_cat_read(
    ctx: &AppContext,
    path: &str,
    predicate: &'static str,
) -> crate::bash_rewrite::RewriteDecision {
    let candidate = resolved_path_candidate(ctx, path);
    crate::slog_warn!(
        "bash rewrite rule cat declined: read declined: predicate={} resolved_candidate={:?}",
        predicate,
        candidate
    );
    decline(
        "cat",
        "cat.decline",
        &format!(
            "read declined: {predicate} failed for {}",
            candidate.display()
        ),
    )
}

fn path_is_safe(ctx: &AppContext, path: &str, require_existing: bool) -> bool {
    let root = grep_project_root(ctx);
    let candidate = path_candidate(ctx, path);
    if require_existing && !candidate.exists() {
        return false;
    }
    let resolved = std::fs::canonicalize(&candidate).unwrap_or(candidate);
    resolved.starts_with(&root)
}

fn read_shape_is_faithful(ctx: &AppContext, path: &str) -> bool {
    let candidate = path_candidate(ctx, path);
    let Ok(metadata) = std::fs::metadata(&candidate) else {
        return false;
    };
    if !metadata.is_file() || metadata.len() > 50 * 1024 {
        return false;
    }
    let Ok(bytes) = std::fs::read(candidate) else {
        return false;
    };
    let Ok(text) = std::str::from_utf8(&bytes) else {
        return false;
    };
    text.lines().all(|line| line.len() <= 2_000)
}

fn effective_hashline_session(ctx: &AppContext, session_id: Option<&str>) -> bool {
    let root = ctx
        .canonical_cache_root_opt()
        .unwrap_or_else(|| grep_project_root(ctx));
    ctx.hashline_bindings()
        .capture(
            root,
            session_id.unwrap_or(crate::protocol::DEFAULT_SESSION_ID),
        )
        .is_some_and(|binding| binding.effective())
}

fn head_tail_shape_is_faithful(ctx: &AppContext, path: &str, lines: usize, tail: bool) -> bool {
    let root = grep_project_root(ctx);
    let candidate = if Path::new(path).is_absolute() {
        Path::new(path).to_path_buf()
    } else {
        root.join(path)
    };
    let Ok(metadata) = std::fs::metadata(&candidate) else {
        return false;
    };
    if !metadata.is_file() {
        return false;
    }
    let Ok(bytes) = std::fs::read(candidate) else {
        return false;
    };
    let Ok(text) = std::str::from_utf8(&bytes) else {
        return false;
    };
    let records = text.lines().collect::<Vec<_>>();
    let selected: Box<dyn Iterator<Item = &&str>> = if tail {
        Box::new(records.iter().skip(records.len().saturating_sub(lines)))
    } else {
        Box::new(records.iter().take(lines))
    };
    let mut displayed_bytes = 0_usize;
    for record in selected {
        if record.len() > 2_000 {
            return false;
        }
        displayed_bytes = displayed_bytes
            .saturating_add(record.len())
            .saturating_add(16);
        if displayed_bytes > 50 * 1024 {
            return false;
        }
    }
    true
}

fn text_file_line_count(path: &Path) -> Option<usize> {
    let bytes = std::fs::read(path).ok()?;
    std::str::from_utf8(&bytes).ok()?;
    if bytes.is_empty() {
        return Some(0);
    }
    Some(
        bytes.iter().filter(|byte| **byte == b'\n').count()
            + usize::from(bytes.last() != Some(&b'\n')),
    )
}

fn append_path_is_safe(ctx: &AppContext, path: &str) -> bool {
    let root = grep_project_root(ctx);
    let candidate = if Path::new(path).is_absolute() {
        Path::new(path).to_path_buf()
    } else {
        root.join(path)
    };
    let parent = candidate.parent().unwrap_or(&root);
    if !parent.exists() {
        return false;
    }
    let resolved_parent = std::fs::canonicalize(parent).unwrap_or_else(|_| parent.to_path_buf());
    if !resolved_parent.starts_with(&root) {
        return false;
    }
    if candidate.exists() {
        let Ok(resolved) = std::fs::canonicalize(&candidate) else {
            return false;
        };
        resolved.starts_with(&root)
    } else {
        true
    }
}

fn grep_request(command: &str, binary: &str) -> Option<Value> {
    let parsed = parse(command)?;
    if parsed.appends_to.is_some() || parsed.heredoc.is_some() || parsed.args.first()? != binary {
        return None;
    }

    let mut case_sensitive = true;
    let mut word_match = false;
    let mut index = 1;

    while let Some(arg) = parsed.args.get(index) {
        if !arg.starts_with('-') || arg == "-" {
            break;
        }
        for flag in arg[1..].chars() {
            match flag {
                'n' | 'r' => {}
                'i' => case_sensitive = false,
                'w' => word_match = true,
                _ => return None,
            }
        }
        index += 1;
    }

    let pattern = parsed.args.get(index)?.clone();
    let path = parsed.args.get(index + 1).cloned();
    if parsed.args.len() > index + 2 {
        return None;
    }

    let pattern = if word_match {
        format!(r"\b(?:{})\b", pattern)
    } else {
        pattern
    };

    if regex::RegexBuilder::new(&pattern)
        .size_limit(REGEX_SIZE_LIMIT)
        .build()
        .is_err()
    {
        return None;
    }

    let mut params = json!({
        "pattern": pattern,
        "case_sensitive": case_sensitive,
        "max_results": 100,
    });
    if let Some(path) = path {
        params["path"] = json!(path);
    }
    Some(params)
}

fn find_request(command: &str) -> Option<Value> {
    let parsed = parse(command)?;
    if parsed.appends_to.is_some() || parsed.heredoc.is_some() || parsed.args.first()? != "find" {
        return None;
    }
    if parsed.args.len() != 4 && parsed.args.len() != 6 {
        return None;
    }

    let path = parsed.args.get(1)?.clone();
    let mut name = None;
    let mut saw_type_file = false;
    let mut index = 2;

    while index < parsed.args.len() {
        match parsed.args[index].as_str() {
            "-name" if name.is_none() && index + 1 < parsed.args.len() => {
                name = Some(parsed.args[index + 1].clone());
                index += 2;
            }
            "-type" if !saw_type_file && index + 1 < parsed.args.len() => {
                if parsed.args[index + 1] != "f" {
                    return None;
                }
                saw_type_file = true;
                index += 2;
            }
            _ => return None,
        }
    }

    let name = name?;
    let pattern = format!("**/{name}");
    if path == "." {
        Some(json!({ "pattern": pattern }))
    } else {
        let trimmed = path.trim_end_matches('/');
        if trimmed.is_empty() {
            // Filesystem root (`find / ...`, `find // ...`): trimming the slash
            // yields "" which downstream resolves as the PROJECT ROOT — silently
            // searching the project instead of the whole filesystem. Don't
            // rewrite; fall through to native `find`, which does what was asked.
            // (A non-empty absolute path like `/tmp/foo` is preserved as-is.)
            None
        } else {
            Some(json!({ "path": trimmed, "pattern": pattern }))
        }
    }
}

fn cat_read_request(command: &str) -> Option<Value> {
    let parsed = parse(command)?;
    if parsed.appends_to.is_some() || parsed.heredoc.is_some() {
        return None;
    }
    if parsed.args.len() != 2 || parsed.args.first()? != "cat" {
        return None;
    }
    Some(json!({ "file": parsed.args[1] }))
}

fn head_tail_read_request(command: &str, command_name: &str) -> Option<Value> {
    let parsed = parse(command)?;
    if parsed.appends_to.is_some()
        || parsed.heredoc.is_some()
        || parsed.args.first()? != command_name
    {
        return None;
    }

    let (lines, file) = match parsed.args.as_slice() {
        [_command, file] => (10_u64, file.as_str()),
        [_command, flag, count, file] if flag == "-n" => {
            (count.parse::<u64>().ok()?, file.as_str())
        }
        [_command, compact, file] => {
            let count = compact.strip_prefix('-')?.parse::<u64>().ok()?;
            (count, file.as_str())
        }
        _ => return None,
    };
    if lines == 0 {
        return None;
    }
    Some(json!({ "file": file, "limit": lines }))
}

fn append_request(command: &str) -> Option<Value> {
    let parsed = parse(command)?;
    let file = parsed.appends_to.clone()?;

    let append_content = if parsed.args == ["cat"] {
        parsed.heredoc?
    } else if parsed.heredoc.is_none()
        && parsed.args.first().is_some_and(|arg| arg == "echo")
        && parsed.args.len() >= 2
        && !parsed.args[1].starts_with('-')
    {
        format!("{}\n", parsed.args[1..].join(" "))
    } else {
        return None;
    };

    Some(json!({
        "op": "append",
        "file": file,
        "append_content": append_content,
        "create_dirs": true,
    }))
}

fn sed_request(command: &str) -> Option<Value> {
    let parsed = parse(command)?;
    if parsed.appends_to.is_some() || parsed.heredoc.is_some() {
        return None;
    }
    if parsed.args.len() != 4 || parsed.args.first()? != "sed" || parsed.args[1] != "-n" {
        return None;
    }

    let range = parsed.args[2].strip_suffix('p')?;
    let (start, end) = range.split_once(',')?;
    let start_line = start.parse::<u32>().ok()?;
    let end_line = end.parse::<u32>().ok()?;
    if start_line == 0 || end_line < start_line {
        return None;
    }

    Some(json!({
        "file": parsed.args[3],
        "start_line": start_line,
        "end_line": end_line,
    }))
}

fn ls_request(command: &str, ctx: &AppContext) -> Option<Value> {
    let parsed = parse(command)?;
    if parsed.appends_to.is_some() || parsed.heredoc.is_some() || parsed.args.first()? != "ls" {
        return None;
    }

    let mut path = None;
    let mut include_hidden = false;
    for arg in parsed.args.iter().skip(1) {
        if let Some(flags) = arg.strip_prefix('-') {
            if flags.is_empty() {
                return None;
            }
            for flag in flags.chars() {
                match flag {
                    // -R: recursive listing — `read` of a directory is
                    // single-level only, but the result is still a useful
                    // approximation of "what's in this tree".
                    'R' => {}
                    // Plain `ls` hides dotfiles, while `read` normally includes
                    // them. Preserve the caller's explicit request to show all
                    // entries without changing direct `read` behavior.
                    'a' => include_hidden = true,
                    // `ls -A` shows hidden entries except `.` and `..`. Keep this
                    // distinct spelling unsupported so native bash preserves its
                    // exact contract.
                    'A' => return None,
                    // -l: long format. Shows size, mtime, permissions, owner.
                    // `read` returns directory entries (no metadata) or file
                    // contents (not metadata at all). Rewriting drops the
                    // info the user asked for, so fall through to real bash.
                    // Reported by user dogfooding the v0.18 bash experimentals.
                    _ => return None,
                }
            }
        } else if path.is_none() {
            path = Some(arg.clone());
        } else {
            return None;
        }
    }

    // Even without -l, `ls FILE` and `read FILE` have entirely different
    // semantics: `ls FILE` echoes the filename, `read FILE` dumps the file
    // contents. The rewrite is only safe when the path resolves to a
    // directory (or is missing/cwd, where `read` of cwd also makes sense).
    // Stat the path and fall through to bash for files.
    let target = path.clone().unwrap_or_else(|| ".".to_string());
    let root = grep_project_root(ctx);
    let target_for_metadata = if Path::new(&target).is_absolute() {
        Path::new(&target).to_path_buf()
    } else {
        root.join(&target)
    };
    if let Ok(metadata) = std::fs::metadata(&target_for_metadata) {
        if !metadata.is_dir() || !path_is_safe(ctx, &target, true) {
            return None;
        }
    } else {
        // Path doesn't exist (yet)? Let bash handle the error itself — its
        // wording is well-known to agents, and rewriting a guaranteed failure
        // would change the native error outcome.
        return None;
    }

    Some(json!({ "file": target, "include_hidden": include_hidden }))
}

#[cfg(test)]
mod tests {
    use std::fs;
    use std::time::{Duration, SystemTime};

    use serde_json::json;

    use super::{find_request, should_suppress_grep_footer, HeadRule, TailRule};
    use crate::bash_rewrite::{RewriteDecision, RewriteRule};
    use crate::config::Config;
    use crate::context::{default_language_provider_factory, AppContext};
    use crate::hashline::integration::RegistrationRequest;
    use crate::protocol::DEFAULT_SESSION_ID;

    fn fixture() -> tempfile::TempDir {
        let dir = tempfile::tempdir().unwrap();
        fs::create_dir(dir.path().join("src")).unwrap();
        fs::write(dir.path().join("src/app.ts"), "foo\n").unwrap();
        dir
    }

    #[test]
    fn single_named_file_suppresses_grep_footer() {
        let dir = fixture();
        assert!(should_suppress_grep_footer(Some("src/app.ts"), dir.path()));
    }

    #[test]
    fn directory_path_keeps_grep_footer() {
        let dir = fixture();
        filetime::set_file_mtime(
            dir.path().join("src"),
            filetime::FileTime::from_system_time(SystemTime::now() - Duration::from_secs(61)),
        )
        .unwrap();
        assert!(!should_suppress_grep_footer(Some("src"), dir.path()));
    }

    #[test]
    fn no_path_keeps_grep_footer() {
        let dir = fixture();
        assert!(!should_suppress_grep_footer(None, dir.path()));
    }

    #[test]
    fn external_file_suppresses_grep_footer() {
        let dir = fixture();
        let external = tempfile::NamedTempFile::new().unwrap();
        assert!(should_suppress_grep_footer(
            external.path().to_str(),
            dir.path()
        ));
    }

    #[test]
    fn freshly_modified_file_suppresses_grep_footer() {
        let dir = fixture();
        let file = dir.path().join("src/app.ts");
        fs::write(&file, "foo\nbar\n").unwrap();
        assert!(should_suppress_grep_footer(file.to_str(), dir.path()));
    }

    #[test]
    fn old_directory_inside_project_root_keeps_grep_footer() {
        let dir = fixture();
        let directory = dir.path().join("src");
        filetime::set_file_mtime(
            &directory,
            filetime::FileTime::from_system_time(SystemTime::now() - Duration::from_secs(61)),
        )
        .unwrap();
        assert!(!should_suppress_grep_footer(Some("src"), dir.path()));
    }

    #[test]
    fn old_file_inside_project_root_suppresses_grep_footer() {
        let dir = fixture();
        let file = dir.path().join("src/app.ts");
        filetime::set_file_mtime(
            &file,
            filetime::FileTime::from_system_time(SystemTime::now() - Duration::from_secs(61)),
        )
        .unwrap();
        assert!(should_suppress_grep_footer(Some("src/app.ts"), dir.path()));
    }

    #[test]
    fn find_absolute_path_uses_glob_path_arg() {
        assert_eq!(
            find_request(r#"find /tmp/foo -name "*.ts" -type f"#),
            Some(json!({ "path": "/tmp/foo", "pattern": "**/*.ts" }))
        );
    }

    #[test]
    fn find_dot_keeps_project_root_relative_pattern() {
        assert_eq!(
            find_request(r#"find . -name "*.ts" -type f"#),
            Some(json!({ "pattern": "**/*.ts" }))
        );
    }

    #[test]
    fn find_relative_path_uses_glob_path_arg() {
        assert_eq!(
            find_request(r#"find ./src -name "*.go""#),
            Some(json!({ "path": "./src", "pattern": "**/*.go" }))
        );
    }

    #[test]
    fn find_trims_trailing_slash_from_path_arg() {
        assert_eq!(
            find_request(r#"find /tmp/foo/ -name "*.ts""#),
            Some(json!({ "path": "/tmp/foo", "pattern": "**/*.ts" }))
        );
    }

    #[test]
    fn find_filesystem_root_is_not_rewritten() {
        // `find /` must NOT rewrite — trimming the slash would yield "" which
        // resolves as the project root, silently searching the wrong scope.
        assert_eq!(find_request(r#"find / -name "*.rs""#), None);
        assert_eq!(find_request(r#"find // -name "*.rs""#), None);
    }

    #[test]
    fn head_and_tail_rewrites_are_hashline_only_and_tail_keeps_absolute_numbering() {
        let dir = fixture();
        let root = fs::canonicalize(dir.path()).unwrap();
        fs::write(root.join("src/app.ts"), "one\ntwo\nthree\nfour\n").unwrap();
        let ctx = AppContext::new(
            default_language_provider_factory(),
            Config {
                project_root: Some(root.clone()),
                experimental_bash_rewrite: true,
                ..Default::default()
            },
        );

        assert!(matches!(
            HeadRule.decide("head -2 src/app.ts", "head-off", None, &ctx),
            RewriteDecision::Decline(_)
        ));
        assert!(matches!(
            TailRule.decide("tail -2 src/app.ts", "tail-off", None, &ctx),
            RewriteDecision::Decline(_)
        ));

        ctx.hashline_bindings().register(
            &root,
            DEFAULT_SESSION_ID.to_string(),
            RegistrationRequest {
                configured_enabled: true,
                edit_slot_survives: true,
            },
        );
        let RewriteDecision::Accept(request) =
            TailRule.decide("tail -2 src/app.ts", "tail-on", None, &ctx)
        else {
            panic!("effective hashline tail should rewrite");
        };
        let response = TailRule.execute(&request, &ctx);
        assert!(response.success, "{}", response.data);
        let content = response.data["content"].as_str().unwrap();
        assert!(content.starts_with("[src/app.ts#"), "{content}");
        assert!(content.contains("3:three\n4:four\n"), "{content}");
    }
}