//! Policy for preserving Git's built-in filesystem monitor.//!//! Codex overrides `core.fsmonitor` so repository configuration cannot select//! an executable helper. Preserve the built-in daemon only when the effective//! value is boolean true and Git advertises daemon support.//!//! The daemon avoids scanning every tracked file and untracked directory://! https://github.com/git/git/blob/94f057755b7941b321fd11fec1b2e3ca5313a4e0/Documentation/git-fsmonitor--daemon.adoc#L49-L57//! https://github.com/git/git/blob/94f057755b7941b321fd11fec1b2e3ca5313a4e0/Documentation/git-update-index.adoc#L545-L550use std::future::Future;/// The safe `core.fsmonitor` override for an internal Git command.#[derive(Clone, Copy, Debug, Eq, PartialEq)]pub enum FsmonitorOverride {    /// Disable repository-selected filesystem monitor helpers.    Disabled,    /// Preserve Git's built-in filesystem monitor daemon.    BuiltIn,}impl FsmonitorOverride {    /// Returns the complete Git configuration override.    pub const fn git_config_arg(self) -> &'static str {        match self {            Self::Disabled => "core.fsmonitor=false",            Self::BuiltIn => "core.fsmonitor=true",        }    }}/// Executes the Git commands required by [`detect_fsmonitor_override`].////// Implementations must return stdout only when Git exits successfully./// Timeouts, spawn or transport failures, signal termination, and nonzero exit/// statuses must return `None`.pub trait FsmonitorProbeRunner: Send {    /// Runs one bounded probe in the target repository.    fn run_probe(&mut self, args: &[&str]) -> impl Future<Output = Option<Vec<u8>>> + Send;}/// Returns the safe filesystem monitor override for the target repository.////// This intentionally probes every time. Effective Git configuration is/// layered, may use conditional includes, and can change while Codex is/// running:/// https://git-scm.com/docs/git-config#SCOPES/// https://git-scm.com/docs/git-config#_conditional_includespub async fn detect_fsmonitor_override(    runner: &mut impl FsmonitorProbeRunner,) -> FsmonitorOverride {    // A typed query converts every matching value before `--get` selects the    // effective one. A shadowed helper path can therefore make a repository-    // local true fail conversion. Query the raw effective value first.    // https://github.com/git/git/blob/94f057755b7941b321fd11fec1b2e3ca5313a4e0/builtin/config.c#L482-L514    // https://github.com/git/git/blob/94f057755b7941b321fd11fec1b2e3ca5313a4e0/builtin/config.c#L611-L614    let Some(config) = runner        .run_probe(&["config", "--null", "--get", "core.fsmonitor"])        .await    else {        return FsmonitorOverride::Disabled;    };    let Some(config) = config.strip_suffix(b"\0") else {        return FsmonitorOverride::Disabled;    };    if config.contains(&0) {        return FsmonitorOverride::Disabled;    }    let Ok(config) = str::from_utf8(config) else {        return FsmonitorOverride::Disabled;    };    // Git accepts these case-insensitive spellings directly, as well as    // valueless keys and nonzero integers. Ask Git to normalize uncommon    // spellings, filtering by the raw effective value before conversion so a    // shadowed helper pathname cannot make the query fail.    // https://github.com/git/git/blob/94f057755b7941b321fd11fec1b2e3ca5313a4e0/parse.c#L158-L181    // https://github.com/git/git/blob/94f057755b7941b321fd11fec1b2e3ca5313a4e0/builtin/config.c#L264-L279    // https://github.com/git/git/blob/94f057755b7941b321fd11fec1b2e3ca5313a4e0/builtin/config.c#L496-L507    let configured = if ["true", "yes", "on"]        .iter()        .any(|value| config.eq_ignore_ascii_case(value))    {        true    } else if ["false", "no", "off"]        .iter()        .any(|value| config.eq_ignore_ascii_case(value))    {        false    } else {        let typed_args = [            "config",            "--null",            "--type=bool",            "--fixed-value",            "--get",            "core.fsmonitor",            config,        ];        matches!(            runner.run_probe(&typed_args).await.as_deref(),            Some(b"true\0")        )    };    if !configured {        return FsmonitorOverride::Disabled;    }    // Git 2.35.1 and older interpret "true" as a hook pathname. Before Git    // 2.26, a successful empty hook response can hide tracked changes. Require    // the feature line Git added specifically for capability checks.    // https://github.com/git/git/blob/94f057755b7941b321fd11fec1b2e3ca5313a4e0/Documentation/config/core.adoc#L90-L99    // https://github.com/git/git/commit/dd77cf61a1a2fbf52c94d0cd986d555ad2ba8a4b    let Some(build_options) = runner.run_probe(&["version", "--build-options"]).await else {        return FsmonitorOverride::Disabled;    };    if build_options        .split(|byte| *byte == b'\n')        .any(|line| line.trim_ascii() == b"feature: fsmonitor--daemon")    {        FsmonitorOverride::BuiltIn    } else {        FsmonitorOverride::Disabled    }}#[cfg(test)]#[path = "fsmonitor_tests.rs"]mod tests;