vtcode_core/tools/

command_args.rs

//! Shared helpers for command-style tool arguments.

use std::path::Path;

use serde_json::Value;

use crate::tools::tool_intent::{command_session_action, command_session_action_in, command_session_action_is};

const INDEXED_COMMAND_TYPE_ERROR: &str = "command array must contain only strings";
const COMMAND_VALUE_TYPE_ERROR: &str = "command must be a string or array of strings";

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) enum WriteStdinDispatch {
    Write,
    Poll,
    Wait,
    Inspect,
    Terminate,
    Close,
}

impl WriteStdinDispatch {
    #[must_use]
    pub(crate) const fn command_session_action(self) -> &'static str {
        match self {
            Self::Write => "write",
            Self::Poll => "poll",
            Self::Wait => "wait",
            Self::Inspect => "inspect",
            Self::Terminate => "terminate",
            Self::Close => "close",
        }
    }
}

pub(crate) fn write_stdin_dispatch(args: &Value) -> Result<WriteStdinDispatch, &'static str> {
    let payload = args.as_object().ok_or("write_stdin requires a JSON object")?;
    if let Some(action) = payload.get("action") {
        let action = action.as_str().ok_or("write_stdin action must be a string")?;
        match action.to_ascii_lowercase().as_str() {
            "wait" => return Ok(WriteStdinDispatch::Wait),
            "inspect" => return Ok(WriteStdinDispatch::Inspect),
            "terminate" => return Ok(WriteStdinDispatch::Terminate),
            "close" => return Ok(WriteStdinDispatch::Close),
            "poll" => {
                if payload.get("chars").is_some_and(|chars| chars.as_str() != Some("")) {
                    return Err("write_stdin poll cannot send chars");
                }
                return Ok(WriteStdinDispatch::Poll);
            }
            "write" => {}
            _ => return Err("write_stdin action must be write, poll, wait, inspect, terminate, or close"),
        }
    }
    let chars = payload
        .get("chars")
        .and_then(Value::as_str)
        .ok_or("write_stdin requires string chars")?;

    if chars.is_empty() {
        Ok(WriteStdinDispatch::Poll)
    } else {
        Ok(WriteStdinDispatch::Write)
    }
}

fn collect_indexed_command_parts(
    payload: &serde_json::Map<String, Value>,
    start_index: usize,
) -> Result<Vec<String>, &'static str> {
    let mut parts = Vec::new();
    let mut index = start_index;
    while let Some(value) = payload.get(&format!("command.{index}")) {
        let Some(part) = value.as_str() else {
            return Err(INDEXED_COMMAND_TYPE_ERROR);
        };
        parts.push(part.to_string());
        index += 1;
    }
    Ok(parts)
}

pub fn has_indexed_command_parts(args: &Value) -> bool {
    let Some(payload) = args.as_object() else {
        return false;
    };

    payload.contains_key("command.0") || payload.contains_key("command.1")
}

pub fn parse_indexed_command_parts(
    payload: &serde_json::Map<String, Value>,
) -> Result<Option<Vec<String>>, &'static str> {
    let zero_based = collect_indexed_command_parts(payload, 0)?;
    if !zero_based.is_empty() {
        return Ok(Some(zero_based));
    }

    let one_based = collect_indexed_command_parts(payload, 1)?;
    if one_based.is_empty() {
        Ok(None)
    } else {
        Ok(Some(one_based))
    }
}

pub fn normalize_indexed_command_args(args: &Value) -> Result<Option<Value>, &'static str> {
    let Some(payload) = args.as_object() else {
        return Ok(None);
    };
    if payload.get("command").is_some() {
        return Ok(None);
    }

    let Some(parts) = parse_indexed_command_parts(payload)? else {
        return Ok(None);
    };

    let mut normalized = payload.clone();
    normalized.insert("command".to_string(), Value::String(shell_words::join(parts.iter().map(String::as_str))));
    Ok(Some(Value::Object(normalized)))
}

pub fn normalized_command_value(args: &Value) -> Result<Option<Value>, &'static str> {
    if let Some(command) = args
        .get("command")
        .or_else(|| args.get("cmd"))
        .or_else(|| args.get("raw_command"))
    {
        return Ok(Some(command.clone()));
    }

    Ok(normalize_indexed_command_args(args)?.and_then(|normalized| normalized.get("command").cloned()))
}

pub fn command_words(args: &Value) -> Result<Option<Vec<String>>, &'static str> {
    let Some(command) = normalized_command_value(args)? else {
        return Ok(None);
    };

    let mut parts = match command {
        Value::String(command) => shell_words::split(&command).map_err(|_e| COMMAND_VALUE_TYPE_ERROR)?,
        Value::Array(values) => values
            .iter()
            .map(|value| value.as_str().map(ToOwned::to_owned).ok_or(COMMAND_VALUE_TYPE_ERROR))
            .collect::<Result<Vec<_>, _>>()?,
        _ => return Err(COMMAND_VALUE_TYPE_ERROR),
    };

    if let Some(extra_args) = args.get("args").and_then(Value::as_array) {
        for value in extra_args {
            let Some(part) = value.as_str() else {
                return Err(COMMAND_VALUE_TYPE_ERROR);
            };
            parts.push(part.to_string());
        }
    }

    if parts.is_empty() { Ok(None) } else { Ok(Some(parts)) }
}

pub fn command_text(args: &Value) -> Result<Option<String>, &'static str> {
    let Some(parts) = command_words(args)? else {
        return Ok(None);
    };
    Ok(Some(shell_words::join(parts.iter().map(String::as_str))))
}

/// Ordered argument keys that may carry a shell command string for display.
///
/// Canonical display precedence shared by the binary's tool summaries so
/// headline and detail extraction can never drift. Safety classification must
/// keep using [`raw_command_text`]/[`command_words`], which re-parse via
/// `shell_words` and intentionally exclude the legacy display-only
/// `bash_command` key that core handlers never execute.
pub const DISPLAY_COMMAND_KEYS: &[&str] = &["command", "raw_command", "bash_command", "cmd"];

/// Display-only extraction of a shell command string plus the key it came from.
///
/// Unlike [`raw_command_text`], array commands are joined with plain spaces
/// (no quoting) because the result is rendered, never executed or re-parsed:
/// `["bash", "-lc", "ls -R"]` displays as `bash -lc ls -R`. The `command` key
/// trims before the emptiness check while other keys use raw emptiness,
/// preserving historical per-key behavior. Indexed `command.N` parts are
/// handled by [`command_words`]'s primary path, not here.
///
/// Returns `None` when no key carries a non-empty command.
pub fn extract_command_text_with_key(args: &Value) -> Option<(String, &'static str)> {
    if let Some(array) = args.get("command").and_then(Value::as_array) {
        let joined: String = array
            .iter()
            .filter_map(|value| value.as_str())
            .filter(|segment| !segment.is_empty())
            .collect::<Vec<_>>()
            .join(" ");
        if !joined.is_empty() {
            return Some((joined, "command"));
        }
    }
    for &key in DISPLAY_COMMAND_KEYS {
        let Some(value) = args.get(key).and_then(Value::as_str) else {
            continue;
        };
        // The `command` key trims before the emptiness check; the others do not,
        // matching historical per-key behavior.
        let (text, ok) = if key == "command" {
            let trimmed = value.trim();
            (trimmed.to_string(), !trimmed.is_empty())
        } else {
            (value.to_string(), !value.is_empty())
        };
        if ok {
            return Some((text, key));
        }
    }
    None
}

fn has_nonempty_string_field(args: &Value, key: &str) -> bool {
    args.get(key)
        .and_then(Value::as_str)
        .map(str::trim)
        .is_some_and(|value| !value.is_empty())
}

pub fn interactive_input_text(args: &Value) -> Option<&str> {
    args.get("input")
        .and_then(Value::as_str)
        .or_else(|| args.get("chars").and_then(Value::as_str))
        .or_else(|| args.get("text").and_then(Value::as_str))
        .filter(|value| !value.is_empty())
}

pub fn session_id_text_from_payload(payload: &serde_json::Map<String, Value>) -> Option<&str> {
    payload
        .get("session_id")
        .or_else(|| payload.get("s"))
        .and_then(Value::as_str)
        .map(str::trim)
        .filter(|value| !value.is_empty())
}

pub fn session_id_text(args: &Value) -> Option<&str> {
    args.as_object().and_then(session_id_text_from_payload)
}

pub fn command_session_missing_required_args(args: &Value) -> Vec<&'static str> {
    if command_session_action(args).is_none() {
        return Vec::new();
    }

    let mut missing = Vec::new();
    if command_session_action_is(args, "run") {
        if command_text(args).ok().flatten().is_none() {
            missing.push("command");
        }
    } else if command_session_action_is(args, "write") {
        if session_id_text(args).is_none() {
            missing.push("session_id");
        }
        if interactive_input_text(args).is_none() {
            missing.push("input or chars or text");
        }
    } else if command_session_action_in(args, &["poll", "wait", "continue", "close"]) {
        if session_id_text(args).is_none() {
            missing.push("session_id");
        }
    } else if command_session_action_is(args, "inspect") {
        let has_session_id = session_id_text(args).is_some();
        let has_spool_path = has_nonempty_string_field(args, "spool_path");
        if !has_session_id && !has_spool_path {
            missing.push("session_id or spool_path");
        }
    } else if command_session_action_is(args, "code") {
        let has_code = has_nonempty_string_field(args, "code") || has_nonempty_string_field(args, "command");
        if !has_code {
            missing.push("code or command");
        }
    }

    missing
}

pub fn command_session_requires_command_safety(args: &Value) -> bool {
    command_session_action_is(args, "run")
}

pub fn working_dir_text_from_payload(payload: &serde_json::Map<String, Value>) -> Option<&str> {
    payload
        .get("working_dir")
        .or_else(|| payload.get("cwd"))
        .or_else(|| payload.get("workdir"))
        .and_then(Value::as_str)
        .map(str::trim)
        .filter(|value| !value.is_empty())
}

pub fn working_dir_text(args: &Value) -> Option<&str> {
    args.as_object().and_then(working_dir_text_from_payload)
}

/// Extract the raw command string from command_session-style arguments without
/// splitting it into words. This is useful for checking shell syntax that
/// would be lost after `shell_words::split`, such as redirections and pipes.
pub fn raw_command_text(args: &Value) -> Option<String> {
    let payload = args.as_object()?;

    if let Some(command) = payload
        .get("command")
        .or_else(|| payload.get("cmd"))
        .or_else(|| payload.get("raw_command"))
    {
        match command {
            Value::String(text) => return Some(text.clone()),
            Value::Array(values) => {
                let parts: Option<Vec<&str>> = values.iter().map(|v| v.as_str()).collect();
                return parts.map(shell_words::join);
            }
            _ => return None,
        }
    }

    let indexed = parse_indexed_command_parts(payload).ok().flatten()?;
    Some(shell_words::join(indexed.iter().map(String::as_str)))
}

/// Complete static-classification candidate, including the quoted argv suffix
/// that execution appends to shell text. Conflicting raw overrides cannot prove
/// one invocation, so callers must fail closed instead of treating it as a read
/// or verifier. Dynamic syntax and command options still need normal validation.
pub(crate) fn shell_command_text_with_args(args: &Value) -> Option<String> {
    let mut command = raw_command_text(args)?;
    if args
        .get("raw_command")
        .and_then(Value::as_str)
        .is_some_and(|raw| raw != command)
    {
        return None;
    }
    if let Some(arguments) = args.get("args") {
        let arguments = arguments.as_array()?;
        let suffix_words = arguments.iter().map(Value::as_str).collect::<Option<Vec<_>>>()?;
        if !suffix_words.is_empty() {
            command.push(' ');
            command.push_str(&shell_words::join(suffix_words));
        }
    }
    Some(command)
}

/// Returns whether a shell command contains syntax whose meaning depends on
/// shell expansion rather than the literal argument text.
///
/// Read-only classification and approval-family learning must only operate on
/// static command shapes. Parameter expansion, command substitution, brace
/// expansion, globbing, and unquoted backslash escapes can otherwise turn a
/// harmless-looking token into a different executable argument at runtime.
pub fn contains_dynamic_shell_syntax(command: &str) -> bool {
    crate::command_safety::shell_parser::contains_dynamic_shell_syntax(command)
}

/// Single-walk result for an `env` / leading-assignment prefix.
///
/// `stripped_start` is the index of the executable that will actually run;
/// `has_injection` reports whether the skipped prefix sets a known
/// config/loader-injection key or uses `env -S` (which re-parses at runtime
/// and cannot be audited). One walk produces both so safety checks never
/// re-scan the same prefix twice and the `env`-flag table cannot drift
/// between the stripping and injection paths.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct EnvPrefixScan {
    stripped_start: usize,
    has_injection: bool,
}

fn is_env_split_string_flag(word: &str) -> bool {
    word == "-S" || word == "--split-string" || word.starts_with("-S") || word.starts_with("--split-string=")
}

fn env_flag_consumes_next(word: &str) -> bool {
    matches!(word, "-u" | "--unset" | "-C" | "--chdir")
}

/// Walk an optional `env` prefix plus leading `KEY=value` assignments once.
///
/// Shared by [`command_words_after_environment_prefix`] (stripping) and
/// [`environment_prefix_has_injection_keys`] (injection audit) so both paths
/// inspect the same command shape. Fail-closed notes:
///
/// - `env -S`/`--split-string` re-parses the rest at runtime: reported as
///   injection with an empty remainder, matching both historical paths.
/// - Words with an empty key (`=foo`) are NOT assignments: scanning stops and
///   they are kept as the program (unknown, therefore mutating). The old
///   stripping path skipped them via a broad `contains('=')` test; stopping is
///   strictly fail-closed and the injection path is unchanged.
fn scan_environment_prefix(words: &[String]) -> EnvPrefixScan {
    let mut start = 0;
    let mut has_injection = false;
    loop {
        if words.get(start).is_some_and(|word| word == "env") {
            start += 1;
            while let Some(word) = words.get(start) {
                if word == "--" {
                    start += 1;
                    break;
                }
                if is_env_split_string_flag(word) {
                    // Split-string re-parses the rest at runtime; cannot audit
                    // assignments. Treat as unsafe with no auditable remainder.
                    return EnvPrefixScan { stripped_start: words.len(), has_injection: true };
                }
                let consumes_next = env_flag_consumes_next(word);
                start += 1;
                if consumes_next {
                    // `-u/--unset` removes a key; `-C/--chdir` takes a path.
                    if words.get(start).is_some() {
                        start += 1;
                    }
                    continue;
                }
                if let Some(key) = env_assignment_key(word) {
                    if is_env_injection_key(key) {
                        has_injection = true;
                    }
                    continue;
                }
                if word.starts_with('-') {
                    continue;
                }
                start -= 1;
                break;
            }
            continue;
        }
        if let Some(key) = words.get(start).and_then(|word| env_assignment_key(word)) {
            if is_env_injection_key(key) {
                has_injection = true;
            }
            start += 1;
            continue;
        }
        break;
    }
    EnvPrefixScan { stripped_start: start, has_injection }
}

/// Skip an optional `env` prefix and leading shell environment assignments.
///
/// The returned slice starts at the executable that will actually run. Keep
/// this helper shared by intent and activity classification so both paths
/// inspect the same command shape.
pub fn command_words_after_environment_prefix(words: &[String]) -> &[String] {
    let scan = scan_environment_prefix(words);
    &words[scan.stripped_start..]
}

/// Exact environment keys that can inject config, load foreign code, or launch
/// helpers into an otherwise read-only program.
const ENV_INJECTION_KEYS: &[&str] = &[
    "GIT_CONFIG_COUNT",
    "GIT_CONFIG_GLOBAL",
    "GIT_CONFIG_SYSTEM",
    "GIT_CONFIG_NOSYSTEM",
    "GIT_EXTERNAL_DIFF",
    "GIT_TEXTCONV",
    "GIT_DIFF_OPTS",
    "GIT_EDITOR",
    "GIT_SEQUENCE_EDITOR",
    "GIT_SSH",
    "GIT_SSH_COMMAND",
    "GIT_EXEC_PATH",
    "LD_PRELOAD",
    "LD_AUDIT",
    "LD_LIBRARY_PATH",
    "DYLD_INSERT_LIBRARIES",
    "DYLD_LIBRARY_PATH",
    "DYLD_FRAMEWORK_PATH",
    "DYLD_FALLBACK_LIBRARY_PATH",
    "BASH_ENV",
    "ENV",
    "SHELLOPTS",
    "PERL5OPT",
    "PYTHONSTARTUP",
    "NODE_OPTIONS",
    "RUBYOPT",
    "EDITOR",
    "VISUAL",
    "PAGER",
];

/// Prefix families that always carry injection payload (`GIT_CONFIG_KEY_n` /
/// `GIT_CONFIG_VALUE_n` pair with `GIT_CONFIG_COUNT`).
const ENV_INJECTION_KEY_PREFIXES: &[&str] = &["GIT_CONFIG_KEY_", "GIT_CONFIG_VALUE_"];

fn env_assignment_key(word: &str) -> Option<&str> {
    if word.starts_with('-') {
        return None;
    }
    let (key, _) = word.split_once('=')?;
    if key.is_empty() {
        return None;
    }
    Some(key)
}

fn is_env_injection_key(key: &str) -> bool {
    ENV_INJECTION_KEYS.contains(&key) || ENV_INJECTION_KEY_PREFIXES.iter().any(|prefix| key.starts_with(prefix))
}

/// Returns whether an `env` / leading-assignment prefix sets a known
/// config-injection or loader-injection key.
///
/// `command_words_after_environment_prefix` strips these assignments so the
/// executable can be classified; the values themselves must still be checked.
/// Unset (`env -u KEY`) is not an assignment. Unknown keys stay allowed so
/// ordinary exploration (`LANG=C rg …`) keeps working.
pub fn environment_prefix_has_injection_keys(words: &[String]) -> bool {
    scan_environment_prefix(words).has_injection
}

/// Return whether a parsed command uses an option or environment assignment
/// that can turn an otherwise read-only inspection program into a writer or
/// command launcher.
///
/// This is deliberately option/env focused; the read-only executable/subcommand
/// allow-list remains in `tool_intent::readonly`. Keeping the unsafe option
/// rules here lets raw argument validation and activity classification share
/// the same token-aware guard without searching quoted text.
pub(crate) fn has_unsafe_readonly_options(words: &[String]) -> bool {
    // Single prefix walk: the scan yields both the injection verdict and the
    // stripped executable offset, replacing the historical two-walk sequence
    // (`environment_prefix_has_injection_keys` then
    // `command_words_after_environment_prefix`).
    let scan = scan_environment_prefix(words);
    if scan.has_injection {
        return true;
    }
    let command_words = &words[scan.stripped_start..];
    let Some(program) = command_words
        .first()
        .and_then(|word| Path::new(word).file_name())
        .and_then(|name| name.to_str())
    else {
        return false;
    };
    let program = program.to_ascii_lowercase();

    match program.as_str() {
        "git" => command_words.iter().skip(1).any(|word| {
            // `-C <dir>` (bare or inline `-C<dir>`) only redirects which
            // repository is read; the subcommand allow-list still gates every
            // git call, so it cannot turn an inspection into a writer. `-c
            // key=value` stays prompt-requiring: config injection is a
            // command-execution vector (fsmonitor/pager hooks).
            let is_dir_redirect = word == "-C" || (word.starts_with("-C") && word.len() > 2);
            (!is_dir_redirect && crate::command_safety::git_global_option_requires_prompt(word))
                || word == "--ext-diff"
                || word == "--textconv"
                || word == "-o"
                || word.starts_with("-o")
                || word == "--output"
                || word.starts_with("--output=")
        }),
        "sed" => has_unsafe_sed_options(&command_words[1..]),
        "find" => command_words.iter().skip(1).any(|word| {
            matches!(
                word.as_str(),
                "-delete" | "-exec" | "-execdir" | "-ok" | "-okdir" | "-fls" | "-fprint" | "-fprint0" | "-fprintf"
            )
        }),
        "sort" => command_words.iter().skip(1).any(|word| {
            word == "-o"
                || word.starts_with("-o")
                || word == "--output"
                || word.starts_with("--output=")
                || word == "--compress-program"
                || word.starts_with("--compress-program=")
        }),
        "date" => command_words
            .iter()
            .skip(1)
            .any(|word| word == "-s" || word.starts_with("-s") || word == "--set" || word.starts_with("--set=")),
        "rg" => command_words.iter().skip(1).any(|word| {
            matches!(word.as_str(), "--pre" | "--hostname-bin" | "--search-zip" | "-z")
                || word.starts_with("--pre=")
                || word.starts_with("--hostname-bin=")
        }),
        "ast-grep" | "sg" => command_words
            .iter()
            .skip(1)
            .any(|word| word == "-r" || word == "--rewrite" || word.starts_with("--rewrite=")),
        "fd" => command_words
            .iter()
            .skip(1)
            .any(|word| word == "-x" || word == "--exec" || word == "--exec-batch" || word.starts_with("--exec=")),
        "tree" => command_words
            .iter()
            .skip(1)
            .any(|word| word == "-o" || word.starts_with("-o") || word == "--output" || word.starts_with("--output=")),
        // `awk` stays on the read-only allow-list, but its program text can
        // write (`print > file`), pipe into commands (`print | "cmd"`),
        // execute them (`system()`), call them indirectly (`@func()`), or
        // load code (`@include`, `@load`), and its options can edit in place
        // (`-i inplace`), load external code (`-l`), or write profiles
        // (`-p`). `has_unsafe_awk_options` fails closed on all of those; only
        // data-only options (`-v`, `-F`) and a write-free program pass.
        "awk" => has_unsafe_awk_options(&command_words[1..]),
        _ => false,
    }
}

fn has_unsafe_sed_options(arguments: &[String]) -> bool {
    let mut expects_expression = false;
    let mut expression_seen = false;

    for word in arguments {
        if expects_expression {
            if sed_script_may_write(word) {
                return true;
            }
            expects_expression = false;
            expression_seen = true;
            continue;
        }

        if word == "-e" || word == "--expression" {
            expects_expression = true;
            continue;
        }
        if let Some(expression) = word.strip_prefix("--expression=") {
            if sed_script_may_write(expression) {
                return true;
            }
            expression_seen = true;
            continue;
        }
        if let Some(expression) = word.strip_prefix("-e")
            && !expression.is_empty()
        {
            if sed_script_may_write(expression) {
                return true;
            }
            expression_seen = true;
            continue;
        }

        if word == "-f"
            || word.starts_with("-f")
            || word.starts_with("--file")
            || word == "-i"
            || word.starts_with("-i")
            || word == "-I"
            || word.starts_with("-I")
            || word.starts_with("--in-place")
        {
            return true;
        }

        if word == "--" {
            expects_expression = true;
            continue;
        }
        if !word.starts_with('-') && !expression_seen {
            if sed_script_may_write(word) {
                return true;
            }
            expression_seen = true;
        }
    }

    // A missing argument makes the command invalid. Treat it as unsafe here
    // so malformed input never receives a read-only classification.
    expects_expression || !expression_seen
}

fn sed_script_may_write(script: &str) -> bool {
    let chars = script.to_ascii_lowercase().chars().collect::<Vec<_>>();
    let mut index = 0;

    while index < chars.len() {
        while chars
            .get(index)
            .is_some_and(|character| character.is_whitespace() || *character == ';')
        {
            index += 1;
        }

        if let Some(after_address) = consume_sed_address(&chars, index) {
            index = after_address;
            if chars.get(index) == Some(&',') {
                index += 1;
                let Some(after_second_address) = consume_sed_address(&chars, index) else {
                    return true;
                };
                index = after_second_address;
            }
            if chars.get(index) == Some(&'!') {
                index += 1;
            }
            while chars.get(index).is_some_and(|character| character.is_whitespace()) {
                index += 1;
            }
        }

        let Some(&command) = chars.get(index) else {
            break;
        };
        match command {
            'e' | 'r' | 'w' => return true,
            's' => {
                let Some(after_replacement) = consume_sed_substitution(&chars, index) else {
                    return true;
                };
                if sed_substitution_may_write(&chars, after_replacement) {
                    return true;
                }
                index = after_replacement;
                while chars.get(index).is_some_and(|character| !matches!(*character, ';' | '\n')) {
                    index += 1;
                }
            }
            _ => {
                while chars.get(index).is_some_and(|character| !matches!(*character, ';' | '\n')) {
                    index += 1;
                }
            }
        }
    }

    false
}

fn consume_sed_address(chars: &[char], start: usize) -> Option<usize> {
    match chars.get(start)? {
        character if character.is_ascii_digit() => {
            let mut index = start + 1;
            while chars.get(index).is_some_and(|character| character.is_ascii_digit()) {
                index += 1;
            }
            Some(index)
        }
        '$' => Some(start + 1),
        '/' => find_unescaped_sed_delimiter(chars, start + 1, '/').map(|index| index + 1),
        _ => None,
    }
}

fn find_unescaped_sed_delimiter(chars: &[char], start: usize, delimiter: char) -> Option<usize> {
    let mut index = start;
    while index < chars.len() {
        if chars[index] == '\\' {
            index = index.saturating_add(2);
            continue;
        }
        if chars[index] == delimiter {
            return Some(index);
        }
        index += 1;
    }
    None
}

fn consume_sed_substitution(chars: &[char], start: usize) -> Option<usize> {
    let delimiter = *chars.get(start + 1)?;
    if delimiter.is_whitespace() {
        return None;
    }
    let pattern_end = find_unescaped_sed_delimiter(chars, start + 2, delimiter)?;
    let replacement_end = find_unescaped_sed_delimiter(chars, pattern_end + 1, delimiter)?;
    Some(replacement_end + 1)
}

fn sed_substitution_may_write(chars: &[char], start: usize) -> bool {
    let mut index = start;
    while chars.get(index).is_some_and(|character| character.is_whitespace()) {
        index += 1;
    }
    matches!(chars.get(index), Some('e' | 'w'))
        && chars
            .get(index + 1)
            .is_none_or(|character| character.is_whitespace() || *character == ';')
}

/// Return whether an `awk` invocation uses an option or program shape that can
/// write workspace state or execute commands.
///
/// Only data-only options pass: `-v`/`--assign` (variable binding) and
/// `-F`/`--field-separator`, each either attached or consuming the next word.
/// Every other option fails closed — `-i`/`--include` edits in place,
/// `-f`/`--file`/`--source` load program text this scanner cannot see,
/// `-l`/`--load` loads native extensions, `-p`/`--profile`,
/// `-W`/`--dump-variables`, and `--pretty-print` write files, and the
/// remaining option surface is too wide to allow-list safely. `--` ends option
/// parsing. The first bare word is the program and must
/// be write-free per [`awk_program_may_write`]; later words are filenames. A
/// missing program is malformed, so it fails closed like the `sed` guard.
fn has_unsafe_awk_options(arguments: &[String]) -> bool {
    let mut program_seen = false;
    let mut options_ended = false;
    let mut index = 0;

    while index < arguments.len() {
        let word = arguments[index].as_str();
        if !options_ended && word == "--" {
            options_ended = true;
            index += 1;
            continue;
        }
        if !options_ended && word.starts_with('-') && word.len() > 1 {
            if word == "-v" || word == "--assign" || word == "-F" || word == "--field-separator" {
                // Value-taking option with a separate argument.
                index += 2;
                continue;
            }
            if word.starts_with("-v")
                || word.starts_with("--assign=")
                || word.starts_with("-F")
                || word.starts_with("--field-separator=")
            {
                // Attached value (`-F:`, `-vlimit=10`).
                index += 1;
                continue;
            }
            return true;
        }
        if !program_seen {
            program_seen = true;
            if awk_program_may_write(word) {
                return true;
            }
        }
        index += 1;
    }

    !program_seen
}

/// Return whether an `awk` program can write files, pipe into commands,
/// execute them, or load external code. Single `>` (output redirection /
/// append `>>`) and bare `|` (command pipe) are writes; `>=` and `||` are
/// comparisons/operators. `system()` runs shell commands; `@` invokes gawk
/// indirect calls (`@func()`) and directives (`@include`, `@load`), which can
/// execute or load arbitrary code — including a `system` name smuggled via `-v`.
///
/// A single `>` is a comparison (not redirection) when it cannot be `print` /
/// `printf` redirection: inside `(...)` / `[...]` parentheses (e.g.
/// `if(p2==0 && i>1)`), or in a statement with no prior `print` / `printf`
/// (e.g. pattern `$3>100`). `print > file`, `print x > file`, and `print >>`
/// stay mutating. `|` stays conservative: only `||` and quoted `"|"` pass.
///
/// Double-quoted string literals are scanned as data: a quoted `"|"` passed to
/// `index()` is a literal, not a command pipe, so the read-only shape
/// `awk '... index(rest,"|") ...' file` is not misclassified. To keep this
/// safe the scanner distinguishes string literals, regex literals (`/.../`),
/// and division using awk's operand-vs-operator rule, so a quote *inside* a
/// regex (`/"/`, `/a"b/`) can never desync string tracking and hide a pipe.
/// `@` and `system()` fail closed everywhere — including inside string and
/// regex literals — and `>`/`|`/`@` inside regex literals stay mutating, so the
/// pinned `/a|b/` and `"a@b"` shapes remain conservative.
fn awk_program_may_write(program: &str) -> bool {
    let chars = program.chars().collect::<Vec<_>>();
    let mut index = 0;
    // Whether the previous significant token can end an operand. This decides
    // whether `/` opens a regex literal or is a division operator.
    let mut prev_operand = false;
    // `print` / `printf` seen in the current statement (reset on `;`/`{`/`}`).
    // A single `>` can only be output redirection inside such a statement;
    // without it (pattern `$3>100`) or inside parens (e.g. `if(i>1)`) it is a
    // numeric comparison. `>>` is always redirection.
    let mut seen_print_in_statement = false;
    let mut paren_depth: usize = 0;
    let mut bracket_depth: usize = 0;
    while index < chars.len() {
        let character = chars[index];
        if character.is_whitespace() {
            index += 1;
            continue;
        }
        if character == '#' {
            // Comments are not AWK syntax. In particular, a commented `(`
            // must not make a later print redirection look parenthesized.
            while index < chars.len() && chars[index] != '\n' {
                index += 1;
            }
            continue;
        }
        if character == '"' {
            index += 1;
            let mut terminated = false;
            while index < chars.len() {
                let inner = chars[index];
                if inner == '\\' {
                    index += 2;
                    continue;
                }
                if inner == '"' {
                    index += 1;
                    terminated = true;
                    break;
                }
                // `@`/`system()` fail closed even inside a literal; `>`/`|`
                // are literal data here and are skipped.
                if inner == '@' {
                    return true;
                }
                if (inner == 's' || inner == 'S') && awk_calls_system(&chars, index) {
                    return true;
                }
                index += 1;
            }
            if !terminated {
                return true;
            }
            prev_operand = true;
            continue;
        }
        if character == '/' && !prev_operand {
            // Regex literal. Quotes are regex content, not string delimiters,
            // so they cannot desync string parsing; `>`/`|`/`@` inside still
            // fail closed, matching the pinned `/a|b/` policy.
            index += 1;
            let mut terminated = false;
            while index < chars.len() {
                let inner = chars[index];
                if inner == '\\' {
                    index += 2;
                    continue;
                }
                if inner == '/' {
                    index += 1;
                    terminated = true;
                    break;
                }
                if inner == '@' {
                    return true;
                }
                if inner == '>' {
                    if chars.get(index + 1) == Some(&'=') {
                        index += 2;
                        continue;
                    }
                    return true;
                }
                if inner == '|' {
                    if chars.get(index + 1) == Some(&'|') {
                        index += 2;
                        continue;
                    }
                    return true;
                }
                index += 1;
            }
            if !terminated {
                return true;
            }
            prev_operand = true;
            continue;
        }
        if character == '@' {
            return true;
        }
        if (character == 's' || character == 'S') && awk_calls_system(&chars, index) {
            return true;
        }
        if character == '>' {
            if chars.get(index + 1) == Some(&'=') {
                index += 2;
                prev_operand = false;
                continue;
            }
            // `>>` is always append-redirection.
            if chars.get(index + 1) == Some(&'>') {
                return true;
            }
            // Single `>` is redirection only inside a `print`/`printf`
            // statement at paren/bracket depth 0. Otherwise it is a numeric
            // comparison (`if(p2==0 && i>1)`, pattern `$3>100`).
            if paren_depth == 0 && bracket_depth == 0 && seen_print_in_statement {
                return true;
            }
            index += 1;
            prev_operand = false;
            continue;
        }
        if character == '|' {
            if chars.get(index + 1) == Some(&'|') {
                index += 2;
                prev_operand = false;
                continue;
            }
            return true;
        }
        if character == '/' {
            // Division: an operand precedes it.
            prev_operand = false;
            index += 1;
            continue;
        }
        if character.is_ascii_alphanumeric() || character == '_' {
            let start = index;
            while index < chars.len() && (chars[index].is_ascii_alphanumeric() || chars[index] == '_') {
                index += 1;
            }
            let word: String = chars[start..index].iter().collect();
            if word == "print" || word == "printf" {
                seen_print_in_statement = true;
            }
            prev_operand = !is_awk_keyword(&word);
            continue;
        }
        if character == '(' {
            paren_depth = paren_depth.saturating_add(1);
            prev_operand = false;
            index += 1;
            continue;
        }
        if character == '[' {
            bracket_depth = bracket_depth.saturating_add(1);
            prev_operand = false;
            index += 1;
            continue;
        }
        if character == ')' {
            paren_depth = paren_depth.saturating_sub(1);
            prev_operand = true;
            index += 1;
            continue;
        }
        if character == ']' {
            bracket_depth = bracket_depth.saturating_sub(1);
            prev_operand = true;
            index += 1;
            continue;
        }
        if character == '$' {
            prev_operand = true;
            index += 1;
            continue;
        }
        if character == ';' || character == '{' || character == '}' {
            // New statement: a later `>` needs its own `print`/`printf`.
            seen_print_in_statement = false;
            prev_operand = false;
            index += 1;
            continue;
        }
        prev_operand = false;
        index += 1;
    }
    false
}

/// Awk keywords that do not end an operand, so a following `/` opens a regex
/// literal (`print /re/`) rather than being a division operator. Kept minimal
/// and conservative: an unlisted keyword is treated as an operand, which at
/// worst misreads a regex as division — still fail-closed, because regex
/// contents are then scanned as top-level code and any `>`/`|`/`@` is caught.
fn is_awk_keyword(word: &str) -> bool {
    matches!(
        word,
        "if" | "else"
            | "while"
            | "for"
            | "do"
            | "break"
            | "continue"
            | "next"
            | "nextfile"
            | "exit"
            | "return"
            | "delete"
            | "in"
            | "getline"
            | "print"
            | "printf"
            | "function"
    )
}

/// Return whether `chars[start..]` invokes awk's `system()` builtin: the
/// identifier `system` (case-insensitive) on an identifier boundary followed
/// by optional whitespace and `(`.
fn awk_calls_system(chars: &[char], start: usize) -> bool {
    const NAME: &[char] = &['s', 'y', 's', 't', 'e', 'm'];
    if start > 0 && is_awk_ident_char(chars[start - 1]) {
        return false;
    }
    let candidate = chars.get(start..start + NAME.len());
    if candidate.is_none_or(|slice| {
        slice
            .iter()
            .zip(NAME.iter())
            .any(|(actual, expected)| !actual.eq_ignore_ascii_case(expected))
    }) {
        return false;
    }
    let mut index = start + NAME.len();
    while chars.get(index).is_some_and(|character| character.is_whitespace()) {
        index += 1;
    }
    chars.get(index) == Some(&'(')
}

fn is_awk_ident_char(character: char) -> bool {
    character.is_ascii_alphanumeric() || character == '_'
}

pub fn normalize_shell_args(args: &Value) -> Result<Value, &'static str> {
    let mut normalized = match normalize_indexed_command_args(args)? {
        Some(value) => value,
        None => args.clone(),
    };

    let Some(payload) = normalized.as_object_mut() else {
        return Ok(normalized);
    };

    if payload.get("command").is_none() {
        if let Some(command) = payload.get("cmd").cloned() {
            payload.insert("command".to_string(), command);
        } else if let Some(command) = payload.get("raw_command").cloned() {
            payload.insert("command".to_string(), command);
        }
    }

    if payload.get("input").is_none() {
        if let Some(input) = payload.get("chars").cloned() {
            payload.insert("input".to_string(), input);
        } else if let Some(input) = payload.get("text").cloned() {
            payload.insert("input".to_string(), input);
        }
    }

    if payload.get("session_id").is_none()
        && let Some(session_id) = payload.get("s").cloned()
    {
        payload.insert("session_id".to_string(), session_id);
    }

    if payload.get("max_tokens").is_none()
        && let Some(max_output_tokens) = payload.get("max_output_tokens").cloned()
    {
        payload.insert("max_tokens".to_string(), max_output_tokens);
    }

    if payload.get("max_output_tokens").is_none()
        && let Some(max_tokens) = payload.get("max_tokens").cloned()
    {
        payload.insert("max_output_tokens".to_string(), max_tokens);
    }

    Ok(normalized)
}

#[cfg(test)]
mod tests {
    use super::{
        WriteStdinDispatch, command_session_missing_required_args, command_session_requires_command_safety,
        command_text, command_words, command_words_after_environment_prefix, contains_dynamic_shell_syntax,
        environment_prefix_has_injection_keys, extract_command_text_with_key, has_indexed_command_parts,
        has_unsafe_readonly_options, interactive_input_text, normalize_indexed_command_args, normalize_shell_args,
        normalized_command_value, parse_indexed_command_parts, raw_command_text, scan_environment_prefix,
        session_id_text, session_id_text_from_payload, working_dir_text, working_dir_text_from_payload,
        write_stdin_dispatch,
    };
    use serde_json::{Value, json};

    #[test]
    fn detects_indexed_command_keys() {
        assert!(has_indexed_command_parts(&json!({"command.0": "ls"})));
        assert!(has_indexed_command_parts(&json!({"command.1": "ls"})));
        assert!(!has_indexed_command_parts(&json!({"command.2": "ls"})));
    }

    #[test]
    fn parses_zero_based_indexed_command_parts() {
        let parts = parse_indexed_command_parts(
            json!({
                "command.0": "ls",
                "command.1": "-a"
            })
            .as_object()
            .expect("object"),
        )
        .expect("valid indexed args");

        assert_eq!(parts, Some(vec!["ls".to_string(), "-a".to_string()]));
    }

    #[test]
    fn parses_one_based_indexed_command_parts() {
        let parts = parse_indexed_command_parts(
            json!({
                "command.1": "ls",
                "command.2": "-a"
            })
            .as_object()
            .expect("object"),
        )
        .expect("valid indexed args");

        assert_eq!(parts, Some(vec!["ls".to_string(), "-a".to_string()]));
    }

    #[test]
    fn rejects_non_string_indexed_command_parts() {
        let error = parse_indexed_command_parts(
            json!({
                "command.0": 42
            })
            .as_object()
            .expect("object"),
        )
        .expect_err("non-string segment should fail");

        assert_eq!(error, "command array must contain only strings");
    }

    #[test]
    fn normalizes_indexed_command_args_into_command_string() {
        let normalized = normalize_indexed_command_args(&json!({
            "command.1": "ls",
            "command.2": "-a",
            "working_dir": "."
        }))
        .expect("valid indexed args")
        .expect("normalized payload");

        assert_eq!(normalized.get("command").and_then(Value::as_str), Some("ls -a"));
        assert_eq!(normalized.get("working_dir").and_then(Value::as_str), Some("."));
    }

    #[test]
    fn normalized_command_value_prefers_cmd_aliases() {
        let normalized = normalized_command_value(&json!({"cmd": "ls -a"}))
            .expect("valid command alias")
            .expect("command value");

        assert_eq!(normalized.as_str(), Some("ls -a"));
    }

    #[test]
    fn command_text_joins_command_arrays() {
        let command = command_text(&json!({"command": ["git", "status", "--short"]}))
            .expect("valid command")
            .expect("command text");

        assert_eq!(command, "git status --short");
    }

    #[test]
    fn command_words_append_extra_args() {
        let words = command_words(&json!({
            "command": "cargo test",
            "args": ["-p", "vtcode-core"]
        }))
        .expect("valid command")
        .expect("command words");

        assert_eq!(words, vec!["cargo", "test", "-p", "vtcode-core"]);
    }

    #[test]
    fn interactive_input_text_preserves_whitespace() {
        assert_eq!(interactive_input_text(&json!({"chars": "  echo hi\n"})), Some("  echo hi\n"));
    }

    #[test]
    fn write_stdin_dispatch_distinguishes_write_from_poll() {
        assert_eq!(write_stdin_dispatch(&json!({"chars": ""})), Ok(WriteStdinDispatch::Poll));
        assert_eq!(write_stdin_dispatch(&json!({"chars": "  status\n"})), Ok(WriteStdinDispatch::Write));
    }

    #[test]
    fn write_stdin_dispatch_accepts_explicit_wait_without_chars() {
        assert_eq!(
            write_stdin_dispatch(&json!({"action": "wait", "session_id": "run-1"})),
            Ok(WriteStdinDispatch::Wait)
        );
    }

    #[test]
    fn write_stdin_dispatch_requires_public_chars() {
        assert_eq!(write_stdin_dispatch(&json!({"input": "status\n"})), Err("write_stdin requires string chars"));
        assert_eq!(write_stdin_dispatch(&json!({"chars": 1})), Err("write_stdin requires string chars"));
    }

    #[test]
    fn write_stdin_dispatch_validates_control_actions() {
        for (action, expected) in [
            ("inspect", WriteStdinDispatch::Inspect),
            ("terminate", WriteStdinDispatch::Terminate),
            ("close", WriteStdinDispatch::Close),
            ("poll", WriteStdinDispatch::Poll),
        ] {
            assert_eq!(write_stdin_dispatch(&json!({"action": action})), Ok(expected));
        }
        assert!(write_stdin_dispatch(&json!({"action": "typo", "chars": "echo unsafe\n"})).is_err());
        assert!(write_stdin_dispatch(&json!({"action": "poll", "chars": "echo unsafe\n"})).is_err());
        assert!(write_stdin_dispatch(&json!({"action": 1, "chars": ""})).is_err());
    }

    #[test]
    fn session_id_text_trims_whitespace() {
        assert_eq!(session_id_text(&json!({"session_id": " run-1 "})), Some("run-1"));
    }

    #[test]
    fn session_id_text_accepts_compact_alias() {
        assert_eq!(session_id_text(&json!({"s": " run-1 "})), Some("run-1"));
    }

    #[test]
    fn session_id_text_from_payload_accepts_aliases() {
        let value = json!({"s": " run-1 "});
        let payload = value.as_object().expect("object");
        assert_eq!(session_id_text_from_payload(payload), Some("run-1"));
    }

    #[test]
    fn working_dir_text_accepts_aliases() {
        assert_eq!(working_dir_text(&json!({"workdir": " src "})), Some("src"));
        assert_eq!(working_dir_text(&json!({"cwd": "."})), Some("."));
    }

    #[test]
    fn working_dir_text_from_payload_accepts_aliases() {
        let value = json!({"workdir": " src "});
        let payload = value.as_object().expect("object");
        assert_eq!(working_dir_text_from_payload(payload), Some("src"));
    }

    #[test]
    fn normalize_shell_args_maps_codex_fields() {
        let normalized = normalize_shell_args(&json!({
            "cmd": "echo hi",
            "chars": "status\n"
        }))
        .expect("valid shell args");

        assert_eq!(normalized.get("command").and_then(Value::as_str), Some("echo hi"));
        assert_eq!(normalized.get("input").and_then(Value::as_str), Some("status\n"));
    }

    #[test]
    fn normalize_shell_args_maps_compact_session_id() {
        let normalized = normalize_shell_args(&json!({
            "s": "run-1"
        }))
        .expect("valid shell args");

        assert_eq!(normalized.get("session_id").and_then(Value::as_str), Some("run-1"));
    }

    #[test]
    fn normalize_shell_args_copies_max_output_tokens_to_max_tokens() {
        let normalized = normalize_shell_args(&json!({
            "command": "echo hi",
            "max_output_tokens": 42
        }))
        .expect("valid shell args");

        assert_eq!(normalized.get("max_output_tokens").and_then(Value::as_u64), Some(42));
        assert_eq!(normalized.get("max_tokens").and_then(Value::as_u64), Some(42));
    }

    #[test]
    fn normalize_shell_args_copies_max_tokens_to_max_output_tokens() {
        let normalized = normalize_shell_args(&json!({
            "command": "echo hi",
            "max_tokens": 42
        }))
        .expect("valid shell args");

        assert_eq!(normalized.get("max_tokens").and_then(Value::as_u64), Some(42));
        assert_eq!(normalized.get("max_output_tokens").and_then(Value::as_u64), Some(42));
    }

    #[test]
    fn command_session_missing_required_args_is_action_aware() {
        assert_eq!(command_session_missing_required_args(&json!({"action": "run"})), vec!["command"]);
        assert_eq!(
            command_session_missing_required_args(&json!({"action": "write", "session_id": "run-1"})),
            vec!["input or chars or text"]
        );
        assert_eq!(
            command_session_missing_required_args(&json!({"action": "inspect"})),
            vec!["session_id or spool_path"]
        );
        assert!(command_session_missing_required_args(&json!({"action": "list"})).is_empty());
    }

    #[test]
    fn command_session_requires_command_safety_only_for_run() {
        assert!(command_session_requires_command_safety(&json!({
            "action": "run",
            "command": "cargo check"
        })));
        assert!(!command_session_requires_command_safety(&json!({
            "action": "poll",
            "session_id": "run-1"
        })));
    }

    #[test]
    fn raw_command_text_extracts_command_string() {
        assert_eq!(raw_command_text(&json!({"command": "rg foo"})), Some("rg foo".to_string()));
        assert_eq!(raw_command_text(&json!({"cmd": "ls -la"})), Some("ls -la".to_string()));
        assert_eq!(
            raw_command_text(&json!({"command.0": "cat", "command.1": "file.txt"})),
            Some("cat file.txt".to_string())
        );
        assert_eq!(raw_command_text(&json!({"command": ["wc", "-l"]})), Some("wc -l".to_string()));
        assert!(raw_command_text(&json!({})).is_none());
    }

    #[test]
    fn display_extraction_reports_key_and_preserves_precedence() {
        assert_eq!(
            extract_command_text_with_key(&json!({"command": ["bash", "-lc", "ls -R"]})),
            Some(("bash -lc ls -R".to_string(), "command"))
        );
        assert_eq!(
            extract_command_text_with_key(&json!({"bash_command": "pwd"})),
            Some(("pwd".to_string(), "bash_command"))
        );
        assert_eq!(
            extract_command_text_with_key(&json!({"raw_command": "cargo test"})),
            Some(("cargo test".to_string(), "raw_command"))
        );
        // Missing `command` must not block later keys (the copilot
        // early-return bug this canonical helper fixes).
        assert_eq!(extract_command_text_with_key(&json!({"cmd": "ls -la"})), Some(("ls -la".to_string(), "cmd")));
        // `command` trims; other keys keep raw emptiness semantics.
        assert_eq!(extract_command_text_with_key(&json!({"command": "  "})), None);
        // First non-empty key in canonical order wins.
        assert_eq!(
            extract_command_text_with_key(
                &json!({"raw_command": "cargo check -p vtcode", "bash_command": "cargo test"})
            ),
            Some(("cargo check -p vtcode".to_string(), "raw_command"))
        );
        assert!(extract_command_text_with_key(&json!({})).is_none());
    }

    #[test]
    fn env_prefix_injection_keys_are_detected() {
        let words = |command: &str| -> Vec<String> { shell_words::split(command).expect("split command") };

        // The A4 vector: config injection via env values reopens the blocked
        // `git -c` path without any `-c` token.
        assert!(environment_prefix_has_injection_keys(&words(
            "env GIT_CONFIG_COUNT=1 GIT_CONFIG_KEY_0=core.fsmonitor GIT_CONFIG_VALUE_0=touch git status"
        )));
        assert!(environment_prefix_has_injection_keys(&words(
            "GIT_CONFIG_COUNT=1 GIT_CONFIG_KEY_0=core.fsmonitor GIT_CONFIG_VALUE_0=touch git status"
        )));
        assert!(environment_prefix_has_injection_keys(&words("env GIT_EXTERNAL_DIFF=evil git diff")));
        assert!(environment_prefix_has_injection_keys(&words("env GIT_TEXTCONV=evil git log")));
        assert!(environment_prefix_has_injection_keys(&words("env LD_PRELOAD=./evil.so ls")));
        assert!(environment_prefix_has_injection_keys(&words("env BASH_ENV=./evil.sh bash -lc 'echo hi'")));
        assert!(environment_prefix_has_injection_keys(&words("env NODE_OPTIONS=--require ./evil.js node --version")));
        // `env -S` re-parses at runtime; cannot audit.
        assert!(environment_prefix_has_injection_keys(&words("env -S 'GIT_CONFIG_COUNT=1 git status'")));

        // Benign env stays allowed.
        assert!(!environment_prefix_has_injection_keys(&words("env LANG=C.UTF-8 rg foo")));
        assert!(!environment_prefix_has_injection_keys(&words("FOO=bar git status")));
        assert!(!environment_prefix_has_injection_keys(&words("env FOO=bar git status")));
        // Unset is not an assignment.
        assert!(!environment_prefix_has_injection_keys(&words("env -u GIT_CONFIG_COUNT git status")));
        assert!(!environment_prefix_has_injection_keys(&words("git status")));
    }

    #[test]
    fn env_prefix_single_scan_agrees_with_both_public_helpers() {
        let words = |command: &str| -> Vec<String> { shell_words::split(command).expect("split command") };
        for command in [
            "git status",
            "env LANG=C.UTF-8 rg foo",
            "FOO=bar LANG=C git status",
            "env FOO=bar git status",
            "env -- FOO=bar git status",
            "env -u GIT_CONFIG_COUNT git status",
            "env -C /tmp git status",
            "env GIT_EXTERNAL_DIFF=evil git diff",
            "GIT_CONFIG_COUNT=1 GIT_CONFIG_KEY_0=k GIT_CONFIG_VALUE_0=v git status",
            "env -S 'GIT_CONFIG_COUNT=1 git status'",
            "env --split-string='x=1 ls'",
        ] {
            let parsed = words(command);
            let scan = scan_environment_prefix(&parsed);
            assert_eq!(command_words_after_environment_prefix(&parsed), &parsed[scan.stripped_start..], "{command}");
            assert_eq!(environment_prefix_has_injection_keys(&parsed), scan.has_injection, "{command}");
        }
    }

    #[test]
    fn env_prefix_empty_key_stays_fail_closed() {
        let words = |command: &str| -> Vec<String> { shell_words::split(command).expect("split command") };
        // `=foo` is not a valid assignment: the executable stays `=foo`
        // (unknown, therefore mutating downstream), never silently stripped.
        for command in ["=foo rg foo", "env =foo rg foo"] {
            let parsed = words(command);
            let stripped = command_words_after_environment_prefix(&parsed);
            assert_eq!(stripped.first().map(String::as_str), Some("=foo"), "{command}");
            assert!(!environment_prefix_has_injection_keys(&parsed), "{command}");
        }
    }

    #[test]
    fn env_prefix_split_string_reports_empty_remainder_and_unsafe() {
        let words = |command: &str| -> Vec<String> { shell_words::split(command).expect("split command") };
        let parsed = words("env -S 'GIT_CONFIG_COUNT=1 git status'");
        assert!(command_words_after_environment_prefix(&parsed).is_empty());
        assert!(environment_prefix_has_injection_keys(&parsed));
        assert!(has_unsafe_readonly_options(&parsed));
    }

    #[test]
    fn has_unsafe_readonly_options_flags_injection_without_second_walk() {
        let words = |command: &str| -> Vec<String> { shell_words::split(command).expect("split command") };
        assert!(has_unsafe_readonly_options(&words("env LD_PRELOAD=./evil.so ls")));
        assert!(has_unsafe_readonly_options(&words("LD_PRELOAD=./evil.so ls")));
        assert!(!has_unsafe_readonly_options(&words("env LANG=C.UTF-8 rg foo")));
        assert!(!has_unsafe_readonly_options(&words("git status")));
    }

    #[test]
    fn dynamic_shell_syntax_allows_quoted_globs_only() {
        assert!(!contains_dynamic_shell_syntax("find src -name '*.rs'"));
        assert!(!contains_dynamic_shell_syntax("find src -name \"*.rs\""));
        assert!(contains_dynamic_shell_syntax("find src -exe$''c touch {} +"));
        assert!(contains_dynamic_shell_syntax("find src -ex{e,}c touch {} +"));
    }
}