//! Filesystem watcher for `.huskies/work/` and `.huskies/project.toml`.
//!
//! Watches the work pipeline directories for file changes, infers the lifecycle
//! stage from the target directory name, auto-commits with a deterministic message,
//! and broadcasts a [`WatcherEvent`] to all connected WebSocket clients.
//!
//! Also watches `.huskies/project.toml` for modifications and broadcasts
//! [`WatcherEvent::ConfigChanged`] so the frontend can reload the agent roster
//! without a server restart.
//!
//! # Debouncing
//! Events are buffered for 300 ms after the last activity. All changes within the
//! window are batched into a single `git add + commit`. This avoids double-commits
//! when `fs::rename` fires both a remove and a create event.
//!
//! # Race conditions
//! If a mutation handler (e.g. `move_story_to_current`) already committed the
//! change, `git commit` will return "nothing to commit". The watcher detects this
//! via exit-code inspection and silently skips the commit while still broadcasting
//! the event so connected clients stay in sync.

use crate::slog;
use notify::{EventKind, RecommendedWatcher, RecursiveMode, Watcher, recommended_watcher};
use serde::Serialize;
use std::path::{Path, PathBuf};
use std::sync::mpsc;
use std::time::{Duration, Instant};
use tokio::sync::broadcast;

/// A lifecycle event emitted by the filesystem watcher.
#[derive(Clone, Debug, Serialize)]
#[serde(tag = "type", rename_all = "snake_case")]
pub enum WatcherEvent {
    /// A work-pipeline file was created, modified, or deleted.
    WorkItem {
        /// Pipeline stage directory (e.g. `"2_current"`, `"5_archived"`).
        stage: String,
        /// Work item ID (filename stem without extension, e.g. `"42_story_my_feature"`).
        item_id: String,
        /// Semantic action inferred from the stage (e.g. `"start"`, `"accept"`).
        action: String,
        /// The deterministic git commit message used (or that would have been used).
        commit_msg: String,
        /// The pipeline stage the item moved FROM, populated for move operations.
        /// `None` for creations, deletions, or synthetic events.
        from_stage: Option<String>,
    },
    /// `.huskies/project.toml` was modified at the project root (not inside a worktree).
    ConfigChanged,
    /// An agent's state changed (started, stopped, completed, etc.).
    /// Triggers a pipeline state refresh so the frontend can update agent
    /// assignments without waiting for a filesystem event.
    AgentStateChanged,
    /// A story encountered a failure (e.g. merge failure).
    /// Triggers an error notification to configured Matrix rooms.
    MergeFailure {
        /// Work item ID (e.g. `"42_story_my_feature"`).
        story_id: String,
        /// Human-readable description of the failure.
        reason: String,
    },
    /// An agent hit an API rate limit.
    /// Triggers a warning notification to configured chat rooms.
    RateLimitWarning {
        /// Work item ID the agent is working on.
        story_id: String,
        /// Name of the agent that hit the rate limit.
        agent_name: String,
    },
    /// A story has been blocked (e.g. retry limit exceeded, empty diff).
    /// Triggers a warning notification to configured chat rooms.
    StoryBlocked {
        /// Work item ID (e.g. `"42_story_my_feature"`).
        story_id: String,
        /// Human-readable reason the story was blocked.
        reason: String,
    },
    /// An agent hit a hard API rate limit and will be blocked until `reset_at`.
    /// Triggers auto-scheduling of a timer and a notification with the resume time.
    RateLimitHardBlock {
        /// Work item ID the agent is working on.
        story_id: String,
        /// Name of the agent that hit the hard rate limit.
        agent_name: String,
        /// UTC instant at which the rate limit resets.
        reset_at: chrono::DateTime<chrono::Utc>,
    },
}

/// Return `true` if `path` is the root-level `.huskies/project.toml` or
/// `.huskies/agents.toml`, i.e. `{git_root}/.huskies/{project,agents}.toml`.
///
/// Returns `false` for paths inside worktree directories (paths containing
/// a `worktrees` component).
pub fn is_config_file(path: &Path, git_root: &Path) -> bool {
    // Reject any path that passes through the worktrees directory.
    if path.components().any(|c| c.as_os_str() == "worktrees") {
        return false;
    }
    let huskies = git_root.join(".huskies");
    path == huskies.join("project.toml") || path == huskies.join("agents.toml")
}

/// Map a pipeline directory name to a (action, commit-message-prefix) pair.
///
/// Used by the CRDT-to-watcher bridge (in `main.rs`) to derive the action and
/// commit message for `WatcherEvent::WorkItem` events.
pub fn stage_metadata(stage: &str, item_id: &str) -> Option<(&'static str, String)> {
    use crate::pipeline_state::Stage;
    let (action, msg) = match Stage::from_dir(stage)? {
        Stage::Backlog => ("create", format!("huskies: create {item_id}")),
        Stage::Coding => ("start", format!("huskies: start {item_id}")),
        Stage::Qa => ("qa", format!("huskies: queue {item_id} for QA")),
        Stage::Merge { .. } => ("merge", format!("huskies: queue {item_id} for merge")),
        Stage::Done { .. } => ("done", format!("huskies: done {item_id}")),
        Stage::Archived { .. } => ("accept", format!("huskies: accept {item_id}")),
    };
    Some((action, msg))
}

/// Return the pipeline stage name for a path if it is a `.md` file living
/// directly inside one of the known work subdirectories, otherwise `None`.
///
/// Explicitly returns `None` for any path under `.huskies/worktrees/` so
/// that code changes made by agents in their isolated worktrees are never
/// auto-committed to master by the watcher.
///
/// Retained for tests; no longer called in production (CRDT drives events).
#[cfg(test)]
fn stage_for_path(path: &Path) -> Option<String> {
    // Reject any path that passes through the worktrees directory.
    if path.components().any(|c| c.as_os_str() == "worktrees") {
        return None;
    }

    if path.extension().is_none_or(|e| e != "md") {
        return None;
    }
    let stage = path
        .parent()
        .and_then(|p| p.file_name())
        .and_then(|n| n.to_str())?;
    matches!(
        stage,
        "1_backlog" | "2_current" | "3_qa" | "4_merge" | "5_done" | "6_archived"
    )
    .then(|| stage.to_string())
}

/// Stage all changes in the work directory and commit with the given message.
///
/// Uses `git add -A .huskies/work/` to catch both additions and deletions in
/// a single commit. Returns `Ok(true)` if a commit was made, `Ok(false)` if
/// there was nothing to commit, and `Err` for unexpected failures.
///
/// Retained for tests; no longer called in production (CRDT drives events).
#[cfg(test)]
fn git_add_work_and_commit(git_root: &Path, message: &str) -> Result<bool, String> {
    let work_rel = PathBuf::from(".huskies").join("work");

    let add_out = std::process::Command::new("git")
        .args(["add", "-A"])
        .arg(&work_rel)
        .current_dir(git_root)
        .output()
        .map_err(|e| format!("git add: {e}"))?;
    if !add_out.status.success() {
        return Err(format!(
            "git add failed: {}",
            String::from_utf8_lossy(&add_out.stderr)
        ));
    }

    let commit_out = std::process::Command::new("git")
        .args(["commit", "-m", message])
        .current_dir(git_root)
        .output()
        .map_err(|e| format!("git commit: {e}"))?;

    if commit_out.status.success() {
        return Ok(true);
    }

    let stderr = String::from_utf8_lossy(&commit_out.stderr);
    let stdout = String::from_utf8_lossy(&commit_out.stdout);
    if stdout.contains("nothing to commit") || stderr.contains("nothing to commit") {
        return Ok(false);
    }

    Err(format!("git commit failed: {stderr}"))
}

/// Stages that represent meaningful git checkpoints (creation and archival).
/// Intermediate stages (current, qa, merge, done) are transient pipeline state
/// that don't need to be committed — they're only relevant while the server is
/// running and are broadcast to WebSocket clients for real-time UI updates.
///
/// Retained for tests; no longer called in production (CRDT drives events).
#[cfg(test)]
const COMMIT_WORTHY_STAGES: &[&str] = &["1_backlog", "5_done", "6_archived"];

/// Return `true` if changes in `stage` should be committed to git.
///
/// Retained for tests; no longer called in production (CRDT drives events).
#[cfg(test)]
fn should_commit_stage(stage: &str) -> bool {
    COMMIT_WORTHY_STAGES.contains(&stage)
}

/// Process a batch of pending (path → stage) entries: commit and broadcast.
///
/// Only files that still exist on disk are used to derive the commit message
/// (they represent the destination of a move or a new file). Deletions are
/// captured by `git add -A .huskies/work/` automatically.
///
/// Only terminal stages (`1_backlog` and `6_archived`) trigger git commits.
/// All stages broadcast a [`WatcherEvent`] so the frontend stays in sync.
///
/// Retained for tests; no longer called in production (CRDT drives events).
#[cfg(test)]
fn flush_pending(
    pending: &std::collections::HashMap<PathBuf, String>,
    git_root: &Path,
    event_tx: &broadcast::Sender<WatcherEvent>,
) {
    use crate::io::story_metadata::clear_front_matter_field;

    // Separate into files that exist (additions) vs gone (deletions).
    let mut additions: Vec<(&PathBuf, &str)> = Vec::new();
    for (path, stage) in pending {
        if path.exists() {
            additions.push((path, stage.as_str()));
        }
    }

    // Pick the commit message from the first addition (the meaningful side of a move).
    // If there are only deletions, use a generic message.
    let (action, item_id, commit_msg) = if let Some((path, stage)) = additions.first() {
        let item = path
            .file_stem()
            .and_then(|s| s.to_str())
            .unwrap_or("unknown");
        if let Some((act, msg)) = stage_metadata(stage, item) {
            (act, item.to_string(), msg)
        } else {
            return;
        }
    } else {
        // Only deletions — pick any pending path for the item name.
        let Some((path, _)) = pending.iter().next() else {
            return;
        };
        let item = path
            .file_stem()
            .and_then(|s| s.to_str())
            .unwrap_or("unknown");
        (
            "remove",
            item.to_string(),
            format!("huskies: remove {item}"),
        )
    };

    // Strip stale merge_failure front matter from any story that has left 4_merge/.
    for (path, stage) in &additions {
        if *stage != "4_merge"
            && let Err(e) = clear_front_matter_field(path, "merge_failure")
        {
            slog!(
                "[watcher] Warning: could not clear merge_failure from {}: {e}",
                path.display()
            );
        }
    }

    // Only commit for terminal stages; intermediate moves are broadcast-only.
    let dest_stage = additions.first().map_or("unknown", |(_, s)| *s);
    let should_commit = should_commit_stage(dest_stage);

    if should_commit {
        slog!("[watcher] flush: {commit_msg}");
        match git_add_work_and_commit(git_root, &commit_msg) {
            Ok(committed) => {
                if committed {
                    slog!("[watcher] committed: {commit_msg}");
                } else {
                    slog!("[watcher] skipped (already committed): {commit_msg}");
                }
            }
            Err(e) => {
                slog!("[watcher] git error: {e}");
                return;
            }
        }
    } else {
        slog!("[watcher] flush (broadcast-only): {commit_msg}");
    }

    // For move operations, find the source stage from deleted entries with matching item_id.
    let from_stage: Option<String> = if !additions.is_empty() {
        pending
            .iter()
            .filter(|(path, _)| !path.exists())
            .find(|(path, _)| path.file_stem().and_then(|s| s.to_str()) == Some(item_id.as_str()))
            .map(|(_, stage)| stage.clone())
    } else {
        None
    };

    // Always broadcast the event so connected WebSocket clients stay in sync.
    let evt = WatcherEvent::WorkItem {
        stage: dest_stage.to_string(),
        item_id,
        action: action.to_string(),
        commit_msg,
        from_stage,
    };
    let _ = event_tx.send(evt);
}

/// Sweep items in `5_done` whose `merged_at` timestamp exceeds the retention
/// duration to `6_archived` via CRDT state transitions.
///
/// All state is read from and written to CRDT — no filesystem access.
/// Worktree pruning is handled separately by the CRDT event subscriber.
pub(crate) fn sweep_done_to_archived(done_retention: Duration) {
    use crate::pipeline_state::{PipelineEvent, Stage, read_all_typed, stage_dir_name, transition};

    for item in read_all_typed() {
        if let Stage::Done { merged_at, .. } = &item.stage {
            let age = chrono::Utc::now()
                .signed_duration_since(*merged_at)
                .to_std()
                .unwrap_or_default();
            if age >= done_retention {
                let story_id = item.story_id.0.clone();
                match transition(item.stage.clone(), PipelineEvent::Accepted) {
                    Ok(new_stage) => {
                        crate::crdt_state::write_item(
                            &story_id,
                            stage_dir_name(&new_stage),
                            None,
                            None,
                            None,
                            Some(false),
                            None,
                            None,
                            None,
                            None,
                        );
                        slog!("[watcher] sweep: promoted {story_id} → 6_archived/");
                    }
                    Err(e) => {
                        slog!("[watcher] sweep: transition error for {story_id}: {e}");
                    }
                }
            }
        }
    }
}

/// Start the filesystem watcher on a dedicated OS thread.
///
/// Watches `.huskies/project.toml` and `.huskies/agents.toml` for config
/// hot-reload, and periodically sweeps `5_done/` → `6_archived/` via CRDT.
///
/// Work-item pipeline events (stage transitions) are no longer driven by
/// filesystem events — they originate from CRDT state changes via
/// [`crate::crdt_state::subscribe`].
///
/// `git_root`      — project root (passed to `git` commands and config loading).
/// `event_tx`      — broadcast sender for `ConfigChanged` events.
/// `watcher_config` — initial sweep configuration loaded from `project.toml`.
pub fn start_watcher(git_root: PathBuf, event_tx: broadcast::Sender<WatcherEvent>) {
    std::thread::spawn(move || {
        let (notify_tx, notify_rx) = mpsc::channel::<notify::Result<notify::Event>>();

        let mut watcher: RecommendedWatcher = match recommended_watcher(move |res| {
            let _ = notify_tx.send(res);
        }) {
            Ok(w) => w,
            Err(e) => {
                slog!("[watcher] failed to create watcher: {e}");
                return;
            }
        };

        // Watch config files for hot-reload.  Work-item directories are NOT
        // watched — CRDT state transitions drive pipeline events now.
        let huskies = git_root.join(".huskies");
        for config_file in [huskies.join("project.toml"), huskies.join("agents.toml")] {
            if config_file.exists()
                && let Err(e) = watcher.watch(&config_file, RecursiveMode::NonRecursive)
            {
                slog!(
                    "[watcher] failed to watch config file {}: {e}",
                    config_file.display()
                );
            }
        }

        slog!("[watcher] watching config files for hot-reload");

        const DEBOUNCE: Duration = Duration::from_millis(300);

        // Whether a config file change is pending in the current debounce window.
        let mut config_changed_pending = false;
        let mut deadline: Option<Instant> = None;

        loop {
            // How long until the debounce window closes (or wait for next event).
            let timeout = deadline.map_or(Duration::from_secs(60), |d| {
                d.saturating_duration_since(Instant::now())
            });

            let flush = match notify_rx.recv_timeout(timeout) {
                Ok(Ok(event)) => {
                    let is_relevant_kind = matches!(
                        event.kind,
                        EventKind::Create(_) | EventKind::Modify(_) | EventKind::Remove(_)
                    );

                    if is_relevant_kind {
                        for path in event.paths {
                            if is_config_file(&path, &git_root) {
                                slog!("[watcher] config change detected: {}", path.display());
                                config_changed_pending = true;
                                deadline = Some(Instant::now() + DEBOUNCE);
                            }
                            // Work-item file changes are intentionally ignored.
                            // CRDT state transitions handle pipeline events.
                        }
                    }
                    false
                }
                Ok(Err(e)) => {
                    slog!("[watcher] notify error: {e}");
                    false
                }
                // Debounce window expired — time to flush.
                Err(mpsc::RecvTimeoutError::Timeout) => true,
                Err(mpsc::RecvTimeoutError::Disconnected) => {
                    slog!("[watcher] channel disconnected, shutting down");
                    break;
                }
            };

            if flush {
                if config_changed_pending {
                    slog!("[watcher] broadcasting agent_config_changed");
                    let _ = event_tx.send(WatcherEvent::ConfigChanged);

                    config_changed_pending = false;
                }
                deadline = None;
            }
        }
    });
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::collections::HashMap;
    use std::fs;
    use tempfile::TempDir;

    /// Initialise a minimal git repo so commit operations work.
    fn init_git_repo(dir: &std::path::Path) {
        use std::process::Command;
        Command::new("git")
            .args(["init"])
            .current_dir(dir)
            .output()
            .expect("git init");
        Command::new("git")
            .args(["config", "user.email", "test@example.com"])
            .current_dir(dir)
            .output()
            .expect("git config email");
        Command::new("git")
            .args(["config", "user.name", "Test"])
            .current_dir(dir)
            .output()
            .expect("git config name");
        Command::new("git")
            .args(["commit", "--allow-empty", "-m", "init"])
            .current_dir(dir)
            .output()
            .expect("git initial commit");
    }

    /// Create the `.huskies/work/{stage}/` dir tree inside `root`.
    fn make_stage_dir(root: &std::path::Path, stage: &str) -> PathBuf {
        let dir = root.join(".huskies").join("work").join(stage);
        fs::create_dir_all(&dir).expect("create stage dir");
        dir
    }

    // ── git_add_work_and_commit ───────────────────────────────────────────────

    #[test]
    fn git_commit_returns_true_when_file_added() {
        let tmp = TempDir::new().unwrap();
        init_git_repo(tmp.path());
        let stage_dir = make_stage_dir(tmp.path(), "2_current");
        fs::write(stage_dir.join("42_story_foo.md"), "---\nname: test\n---\n").unwrap();

        let result = git_add_work_and_commit(tmp.path(), "huskies: start 42_story_foo");
        assert_eq!(
            result,
            Ok(true),
            "should return Ok(true) when a commit was made"
        );
    }

    #[test]
    fn git_commit_returns_false_when_nothing_to_commit() {
        let tmp = TempDir::new().unwrap();
        init_git_repo(tmp.path());
        let stage_dir = make_stage_dir(tmp.path(), "2_current");
        fs::write(stage_dir.join("42_story_foo.md"), "---\nname: test\n---\n").unwrap();

        // First commit — should succeed.
        git_add_work_and_commit(tmp.path(), "huskies: start 42_story_foo").unwrap();

        // Second call with no changes — should return Ok(false).
        let result = git_add_work_and_commit(tmp.path(), "huskies: start 42_story_foo");
        assert_eq!(
            result,
            Ok(false),
            "should return Ok(false) when nothing to commit"
        );
    }

    // ── flush_pending ─────────────────────────────────────────────────────────

    #[test]
    fn flush_pending_commits_and_broadcasts_for_terminal_stage() {
        let tmp = TempDir::new().unwrap();
        init_git_repo(tmp.path());
        let stage_dir = make_stage_dir(tmp.path(), "1_backlog");
        let story_path = stage_dir.join("42_story_foo.md");
        fs::write(&story_path, "---\nname: test\n---\n").unwrap();

        let (tx, mut rx) = tokio::sync::broadcast::channel(16);
        let mut pending = HashMap::new();
        pending.insert(story_path, "1_backlog".to_string());

        flush_pending(&pending, tmp.path(), &tx);

        let evt = rx.try_recv().expect("expected a broadcast event");
        match evt {
            WatcherEvent::WorkItem {
                stage,
                item_id,
                action,
                commit_msg,
                ..
            } => {
                assert_eq!(stage, "1_backlog");
                assert_eq!(item_id, "42_story_foo");
                assert_eq!(action, "create");
                assert_eq!(commit_msg, "huskies: create 42_story_foo");
            }
            other => panic!("unexpected event: {other:?}"),
        }

        // Verify the file was actually committed.
        let log = std::process::Command::new("git")
            .args(["log", "--oneline", "-1"])
            .current_dir(tmp.path())
            .output()
            .expect("git log");
        let log_msg = String::from_utf8_lossy(&log.stdout);
        assert!(
            log_msg.contains("huskies: create 42_story_foo"),
            "terminal stage should produce a git commit"
        );
    }

    #[test]
    fn flush_pending_broadcasts_without_commit_for_intermediate_stage() {
        let tmp = TempDir::new().unwrap();
        init_git_repo(tmp.path());
        let stage_dir = make_stage_dir(tmp.path(), "2_current");
        let story_path = stage_dir.join("42_story_foo.md");
        fs::write(&story_path, "---\nname: test\n---\n").unwrap();

        let (tx, mut rx) = tokio::sync::broadcast::channel(16);
        let mut pending = HashMap::new();
        pending.insert(story_path, "2_current".to_string());

        flush_pending(&pending, tmp.path(), &tx);

        // Event should still be broadcast for frontend sync.
        let evt = rx.try_recv().expect("expected a broadcast event");
        match evt {
            WatcherEvent::WorkItem {
                stage,
                item_id,
                action,
                commit_msg,
                ..
            } => {
                assert_eq!(stage, "2_current");
                assert_eq!(item_id, "42_story_foo");
                assert_eq!(action, "start");
                assert_eq!(commit_msg, "huskies: start 42_story_foo");
            }
            other => panic!("unexpected event: {other:?}"),
        }

        // Verify NO git commit was made (only the initial empty commit should exist).
        let log = std::process::Command::new("git")
            .args(["log", "--oneline"])
            .current_dir(tmp.path())
            .output()
            .expect("git log");
        let log_msg = String::from_utf8_lossy(&log.stdout);
        assert!(
            !log_msg.contains("huskies:"),
            "intermediate stage should NOT produce a git commit"
        );
    }

    #[test]
    fn flush_pending_broadcasts_for_all_pipeline_stages() {
        let stages = [
            ("1_backlog", "create", "huskies: create 10_story_x"),
            ("3_qa", "qa", "huskies: queue 10_story_x for QA"),
            ("4_merge", "merge", "huskies: queue 10_story_x for merge"),
            ("5_done", "done", "huskies: done 10_story_x"),
            ("6_archived", "accept", "huskies: accept 10_story_x"),
        ];

        for (stage, expected_action, expected_msg) in stages {
            let tmp = TempDir::new().unwrap();
            init_git_repo(tmp.path());
            let stage_dir = make_stage_dir(tmp.path(), stage);
            let story_path = stage_dir.join("10_story_x.md");
            fs::write(&story_path, "---\nname: test\n---\n").unwrap();

            let (tx, mut rx) = tokio::sync::broadcast::channel(16);
            let mut pending = HashMap::new();
            pending.insert(story_path, stage.to_string());

            flush_pending(&pending, tmp.path(), &tx);

            // All stages should broadcast events regardless of commit behavior.
            let evt = rx.try_recv().expect("expected broadcast for stage {stage}");
            match evt {
                WatcherEvent::WorkItem {
                    action, commit_msg, ..
                } => {
                    assert_eq!(action, expected_action, "stage {stage}");
                    assert_eq!(commit_msg, expected_msg, "stage {stage}");
                }
                other => panic!("unexpected event for stage {stage}: {other:?}"),
            }
        }
    }

    #[test]
    fn flush_pending_deletion_only_broadcasts_remove_event() {
        let tmp = TempDir::new().unwrap();
        init_git_repo(tmp.path());
        // Create the work dir tree but NOT the file (simulates a deletion).
        make_stage_dir(tmp.path(), "2_current");
        let deleted_path = tmp
            .path()
            .join(".huskies")
            .join("work")
            .join("2_current")
            .join("42_story_foo.md");

        let (tx, mut rx) = tokio::sync::broadcast::channel(16);
        let mut pending = HashMap::new();
        pending.insert(deleted_path, "2_current".to_string());

        flush_pending(&pending, tmp.path(), &tx);

        // Even when nothing was committed (file never existed), an event is broadcast.
        let evt = rx
            .try_recv()
            .expect("expected a broadcast event for deletion");
        match evt {
            WatcherEvent::WorkItem {
                action, item_id, ..
            } => {
                assert_eq!(action, "remove");
                assert_eq!(item_id, "42_story_foo");
            }
            other => panic!("unexpected event: {other:?}"),
        }
    }

    #[test]
    fn flush_pending_skips_unknown_stage_for_addition() {
        let tmp = TempDir::new().unwrap();
        init_git_repo(tmp.path());
        // File sits in an unrecognised directory.
        let unknown_dir = tmp.path().join(".huskies").join("work").join("9_unknown");
        fs::create_dir_all(&unknown_dir).unwrap();
        let path = unknown_dir.join("42_story_foo.md");
        fs::write(&path, "---\nname: test\n---\n").unwrap();

        let (tx, mut rx) = tokio::sync::broadcast::channel(16);
        let mut pending = HashMap::new();
        pending.insert(path, "9_unknown".to_string());

        flush_pending(&pending, tmp.path(), &tx);

        // No event should be broadcast because stage_metadata returns None for unknown stages.
        assert!(
            rx.try_recv().is_err(),
            "no event should be broadcast for unknown stage"
        );
    }

    #[test]
    fn flush_pending_empty_pending_does_nothing() {
        let tmp = TempDir::new().unwrap();
        init_git_repo(tmp.path());
        make_stage_dir(tmp.path(), "2_current");

        let (tx, mut rx) = tokio::sync::broadcast::channel(16);
        let pending: HashMap<PathBuf, String> = HashMap::new();

        // Should not panic and should not broadcast anything.
        flush_pending(&pending, tmp.path(), &tx);
        assert!(rx.try_recv().is_err(), "no event for empty pending map");
    }

    // ── flush_pending clears merge_failure ─────────────────────────────────────

    #[test]
    fn flush_pending_clears_merge_failure_when_leaving_merge_stage() {
        let tmp = TempDir::new().unwrap();
        init_git_repo(tmp.path());
        let stage_dir = make_stage_dir(tmp.path(), "2_current");
        let story_path = stage_dir.join("50_story_retry.md");
        fs::write(
            &story_path,
            "---\nname: Retry Story\nmerge_failure: \"conflicts detected\"\n---\n# Story\n",
        )
        .unwrap();

        let (tx, _rx) = tokio::sync::broadcast::channel(16);
        let mut pending = HashMap::new();
        pending.insert(story_path.clone(), "2_current".to_string());

        flush_pending(&pending, tmp.path(), &tx);

        let contents = fs::read_to_string(&story_path).unwrap();
        assert!(
            !contents.contains("merge_failure"),
            "merge_failure should be stripped when story lands in 2_current"
        );
        assert!(contents.contains("name: Retry Story"));
    }

    #[test]
    fn flush_pending_clears_merge_failure_when_moving_to_backlog() {
        let tmp = TempDir::new().unwrap();
        init_git_repo(tmp.path());
        let stage_dir = make_stage_dir(tmp.path(), "1_backlog");
        let story_path = stage_dir.join("51_story_reset.md");
        fs::write(
            &story_path,
            "---\nname: Reset Story\nmerge_failure: \"gate failed\"\n---\n# Story\n",
        )
        .unwrap();

        let (tx, _rx) = tokio::sync::broadcast::channel(16);
        let mut pending = HashMap::new();
        pending.insert(story_path.clone(), "1_backlog".to_string());

        flush_pending(&pending, tmp.path(), &tx);

        let contents = fs::read_to_string(&story_path).unwrap();
        assert!(
            !contents.contains("merge_failure"),
            "merge_failure should be stripped when story lands in 1_backlog"
        );
    }

    #[test]
    fn flush_pending_clears_merge_failure_when_moving_to_done() {
        let tmp = TempDir::new().unwrap();
        init_git_repo(tmp.path());
        let stage_dir = make_stage_dir(tmp.path(), "5_done");
        let story_path = stage_dir.join("52_story_done.md");
        fs::write(
            &story_path,
            "---\nname: Done Story\nmerge_failure: \"stale error\"\n---\n# Story\n",
        )
        .unwrap();

        let (tx, _rx) = tokio::sync::broadcast::channel(16);
        let mut pending = HashMap::new();
        pending.insert(story_path.clone(), "5_done".to_string());

        flush_pending(&pending, tmp.path(), &tx);

        let contents = fs::read_to_string(&story_path).unwrap();
        assert!(
            !contents.contains("merge_failure"),
            "merge_failure should be stripped when story lands in 5_done"
        );
    }

    #[test]
    fn flush_pending_preserves_merge_failure_when_in_merge_stage() {
        let tmp = TempDir::new().unwrap();
        init_git_repo(tmp.path());
        let stage_dir = make_stage_dir(tmp.path(), "4_merge");
        let story_path = stage_dir.join("53_story_merging.md");
        fs::write(
            &story_path,
            "---\nname: Merging Story\nmerge_failure: \"conflicts\"\n---\n# Story\n",
        )
        .unwrap();

        let (tx, _rx) = tokio::sync::broadcast::channel(16);
        let mut pending = HashMap::new();
        pending.insert(story_path.clone(), "4_merge".to_string());

        flush_pending(&pending, tmp.path(), &tx);

        let contents = fs::read_to_string(&story_path).unwrap();
        assert!(
            contents.contains("merge_failure"),
            "merge_failure should be preserved when story is in 4_merge"
        );
    }

    #[test]
    fn flush_pending_no_op_when_no_merge_failure() {
        let tmp = TempDir::new().unwrap();
        init_git_repo(tmp.path());
        let stage_dir = make_stage_dir(tmp.path(), "2_current");
        let story_path = stage_dir.join("54_story_clean.md");
        let original = "---\nname: Clean Story\n---\n# Story\n";
        fs::write(&story_path, original).unwrap();

        let (tx, _rx) = tokio::sync::broadcast::channel(16);
        let mut pending = HashMap::new();
        pending.insert(story_path.clone(), "2_current".to_string());

        flush_pending(&pending, tmp.path(), &tx);

        let contents = fs::read_to_string(&story_path).unwrap();
        assert_eq!(
            contents, original,
            "file without merge_failure should be unchanged"
        );
    }

    // ── flush_pending from_stage ─────────────────────────────────────────────

    /// AC3: when a pending map contains both a deletion (source stage) and a
    /// creation (dest stage) for the same item_id, the broadcast event should
    /// have `from_stage` set to the source stage key.
    #[test]
    fn flush_pending_sets_from_stage_for_move_operations() {
        let tmp = TempDir::new().unwrap();
        init_git_repo(tmp.path());

        // Destination exists (file moved here).
        let merge_dir = make_stage_dir(tmp.path(), "4_merge");
        let merge_path = merge_dir.join("42_story_foo.md");
        fs::write(&merge_path, "---\nname: test\n---\n").unwrap();

        // Source path does NOT exist (file was moved away).
        make_stage_dir(tmp.path(), "3_qa");
        let qa_path = tmp
            .path()
            .join(".huskies")
            .join("work")
            .join("3_qa")
            .join("42_story_foo.md");

        let (tx, mut rx) = tokio::sync::broadcast::channel(16);
        let mut pending = HashMap::new();
        pending.insert(merge_path, "4_merge".to_string()); // addition
        pending.insert(qa_path, "3_qa".to_string()); // deletion

        flush_pending(&pending, tmp.path(), &tx);

        let evt = rx.try_recv().expect("expected event");
        match evt {
            WatcherEvent::WorkItem {
                stage, from_stage, ..
            } => {
                assert_eq!(stage, "4_merge");
                assert_eq!(from_stage, Some("3_qa".to_string()));
            }
            other => panic!("unexpected event: {other:?}"),
        }
    }

    /// AC3: when a pending map has only an addition (creation, not a move),
    /// `from_stage` should be `None`.
    #[test]
    fn flush_pending_sets_from_stage_to_none_for_creations() {
        let tmp = TempDir::new().unwrap();
        init_git_repo(tmp.path());

        let stage_dir = make_stage_dir(tmp.path(), "2_current");
        let story_path = stage_dir.join("55_story_new.md");
        fs::write(&story_path, "---\nname: New Story\n---\n").unwrap();

        let (tx, mut rx) = tokio::sync::broadcast::channel(16);
        let mut pending = HashMap::new();
        pending.insert(story_path, "2_current".to_string());

        flush_pending(&pending, tmp.path(), &tx);

        let evt = rx.try_recv().expect("expected event");
        match evt {
            WatcherEvent::WorkItem { from_stage, .. } => {
                assert_eq!(from_stage, None, "creation should have no from_stage");
            }
            other => panic!("unexpected event: {other:?}"),
        }
    }

    // ── stage_for_path (additional edge cases) ────────────────────────────────

    #[test]
    fn stage_for_path_recognises_pipeline_dirs() {
        let base = PathBuf::from("/proj/.huskies/work");
        assert_eq!(
            stage_for_path(&base.join("2_current/42_story_foo.md")),
            Some("2_current".to_string())
        );
        assert_eq!(
            stage_for_path(&base.join("5_done/10_bug_bar.md")),
            Some("5_done".to_string())
        );
        assert_eq!(
            stage_for_path(&base.join("6_archived/10_bug_bar.md")),
            Some("6_archived".to_string())
        );
        assert_eq!(stage_for_path(&base.join("other/file.md")), None);
        assert_eq!(
            stage_for_path(&base.join("2_current/42_story_foo.txt")),
            None
        );
    }

    #[test]
    fn stage_for_path_ignores_worktree_paths() {
        let worktrees = PathBuf::from("/proj/.huskies/worktrees");

        // Code changes inside a worktree must be ignored.
        assert_eq!(
            stage_for_path(&worktrees.join("42_story_foo/server/src/main.rs")),
            None,
        );

        // Even if a worktree happens to contain a path component that looks
        // like a pipeline stage, it must still be ignored.
        assert_eq!(
            stage_for_path(&worktrees.join("42_story_foo/.huskies/work/2_current/42_story_foo.md")),
            None,
        );

        // A path that only contains the word "worktrees" as part of a longer
        // segment (not an exact component) must NOT be filtered out.
        assert_eq!(
            stage_for_path(&PathBuf::from(
                "/proj/.huskies/work/2_current/not_worktrees_story.md"
            )),
            Some("2_current".to_string()),
        );
    }

    #[test]
    fn should_commit_stage_only_for_terminal_stages() {
        // Terminal stages — should commit.
        assert!(should_commit_stage("1_backlog"));
        assert!(should_commit_stage("5_done"));
        assert!(should_commit_stage("6_archived"));
        // Intermediate stages — broadcast-only, no commit.
        assert!(!should_commit_stage("2_current"));
        assert!(!should_commit_stage("3_qa"));
        assert!(!should_commit_stage("4_merge"));
        // Unknown — no commit.
        assert!(!should_commit_stage("unknown"));
    }

    #[test]
    fn stage_metadata_returns_correct_actions() {
        let (action, msg) = stage_metadata("2_current", "42_story_foo").unwrap();
        assert_eq!(action, "start");
        assert_eq!(msg, "huskies: start 42_story_foo");

        let (action, msg) = stage_metadata("5_done", "42_story_foo").unwrap();
        assert_eq!(action, "done");
        assert_eq!(msg, "huskies: done 42_story_foo");

        let (action, msg) = stage_metadata("6_archived", "42_story_foo").unwrap();
        assert_eq!(action, "accept");
        assert_eq!(msg, "huskies: accept 42_story_foo");

        assert!(stage_metadata("unknown", "id").is_none());
    }

    #[test]
    fn is_config_file_identifies_root_project_toml() {
        let git_root = PathBuf::from("/proj");
        let config = git_root.join(".huskies").join("project.toml");
        assert!(is_config_file(&config, &git_root));
    }

    #[test]
    fn is_config_file_identifies_root_agents_toml() {
        let git_root = PathBuf::from("/proj");
        let agents = git_root.join(".huskies").join("agents.toml");
        assert!(is_config_file(&agents, &git_root));
    }

    #[test]
    fn is_config_file_rejects_worktree_copies() {
        let git_root = PathBuf::from("/proj");
        // project.toml inside a worktree must NOT be treated as the root config.
        let worktree_config =
            PathBuf::from("/proj/.huskies/worktrees/42_story_foo/.huskies/project.toml");
        assert!(!is_config_file(&worktree_config, &git_root));
    }

    #[test]
    fn is_config_file_rejects_other_files() {
        let git_root = PathBuf::from("/proj");
        // Random files must not match.
        assert!(!is_config_file(
            &PathBuf::from("/proj/.huskies/work/2_current/42_story_foo.md"),
            &git_root
        ));
        assert!(!is_config_file(
            &PathBuf::from("/proj/.huskies/README.md"),
            &git_root
        ));
    }

    #[test]
    fn is_config_file_rejects_wrong_root() {
        let git_root = PathBuf::from("/proj");
        let other_root_config = PathBuf::from("/other/.huskies/project.toml");
        assert!(!is_config_file(&other_root_config, &git_root));
    }

    // ── sweep_done_to_archived (CRDT-based) ─────────────────────────────────
    //
    // The sweep function reads from `read_all_typed()` and checks
    // `Stage::Done { merged_at, .. }`.  Items created via
    // `write_item_with_content("5_done")` project `merged_at = Utc::now()`,
    // so we test with Duration::ZERO to sweep immediately and with a long
    // retention to verify items are kept.  No filesystem access is involved.

    #[test]
    fn sweep_moves_old_items_to_archived() {
        crate::db::ensure_content_store();
        crate::db::write_item_with_content(
            "9880_story_sweep_old",
            "5_done",
            "---\nname: old\n---\n",
        );

        // With ZERO retention, any Done item should be swept.
        sweep_done_to_archived(Duration::ZERO);

        // Verify the item was moved to 6_archived in the CRDT.
        let items = crate::pipeline_state::read_all_typed();
        let item = items
            .iter()
            .find(|i| i.story_id.0 == "9880_story_sweep_old");
        assert!(
            item.is_some_and(|i| matches!(i.stage, crate::pipeline_state::Stage::Archived { .. })),
            "item should be archived after sweep"
        );
    }

    #[test]
    fn sweep_keeps_recent_items_in_done() {
        crate::db::ensure_content_store();
        crate::db::write_item_with_content(
            "9881_story_sweep_new",
            "5_done",
            "---\nname: new\n---\n",
        );

        // With a very long retention, the item (merged_at ≈ now) should stay.
        sweep_done_to_archived(Duration::from_secs(999_999));

        let items = crate::pipeline_state::read_all_typed();
        let item = items
            .iter()
            .find(|i| i.story_id.0 == "9881_story_sweep_new");
        assert!(
            item.is_some_and(|i| matches!(i.stage, crate::pipeline_state::Stage::Done { .. })),
            "item should remain in Done with long retention"
        );
    }

    #[test]
    fn sweep_respects_custom_retention() {
        crate::db::ensure_content_store();
        crate::db::write_item_with_content(
            "9882_story_sweep_custom",
            "5_done",
            "---\nname: custom\n---\n",
        );

        // With ZERO retention, sweep should promote.
        sweep_done_to_archived(Duration::ZERO);

        let items = crate::pipeline_state::read_all_typed();
        let item = items
            .iter()
            .find(|i| i.story_id.0 == "9882_story_sweep_custom");
        assert!(
            item.is_some_and(|i| matches!(i.stage, crate::pipeline_state::Stage::Archived { .. })),
            "item should be archived with zero retention"
        );
    }

    /// Prove that the sweep reads `merged_at` from the CRDT (not `Utc::now()`).
    ///
    /// This test sets `merged_at` to 10 seconds in the past and uses a 5-second
    /// retention.  If the sweep were still using `Utc::now()` as the start time
    /// (the original bug), the elapsed time would be ~0 and the item would NOT
    /// be swept.  With the fix, the item is swept because 10s > 5s retention.
    #[test]
    fn sweep_uses_crdt_merged_at_not_utc_now() {
        crate::db::ensure_content_store();

        let ten_seconds_ago =
            (chrono::Utc::now() - chrono::Duration::seconds(10)).timestamp() as f64;

        // Write item in 5_done with an explicit past merged_at timestamp.
        crate::crdt_state::write_item(
            "9883_story_sweep_merged_at",
            "5_done",
            Some("merged_at test"),
            None,
            None,
            None,
            None,
            None,
            None,
            Some(ten_seconds_ago),
        );

        // 5-second retention: item is 10s old → should be swept.
        sweep_done_to_archived(Duration::from_secs(5));

        let items = crate::pipeline_state::read_all_typed();
        let item = items
            .iter()
            .find(|i| i.story_id.0 == "9883_story_sweep_merged_at");
        assert!(
            item.is_some_and(|i| matches!(i.stage, crate::pipeline_state::Stage::Archived { .. })),
            "item with merged_at 10s ago should be archived with 5s retention"
        );
    }

    /// Prove that an item with merged_at NEWER than done_retention is NOT swept.
    #[test]
    fn sweep_keeps_item_newer_than_retention() {
        crate::db::ensure_content_store();

        let one_second_ago = (chrono::Utc::now() - chrono::Duration::seconds(1)).timestamp() as f64;

        crate::crdt_state::write_item(
            "9884_story_sweep_recent",
            "5_done",
            Some("recent merged_at test"),
            None,
            None,
            None,
            None,
            None,
            None,
            Some(one_second_ago),
        );

        // 1-hour retention: item is only 1s old → should NOT be swept.
        sweep_done_to_archived(Duration::from_secs(3600));

        let items = crate::pipeline_state::read_all_typed();
        let item = items
            .iter()
            .find(|i| i.story_id.0 == "9884_story_sweep_recent");
        assert!(
            item.is_some_and(|i| matches!(i.stage, crate::pipeline_state::Stage::Done { .. })),
            "item with merged_at 1s ago should stay in Done with 1-hour retention"
        );
    }
}
