//! Pipeline advance — moves stories forward through pipeline stages after agent completion.
use crate::config::ProjectConfig;
use crate::slog;
use crate::slog_error;
use crate::slog_warn;
use crate::io::watcher::WatcherEvent;
use std::collections::HashMap;
use std::path::{Path, PathBuf};
use std::sync::{Arc, Mutex};
use tokio::sync::broadcast;

use super::super::super::{
    CompletionReport, PipelineStage,
    agent_config_stage, pipeline_stage,
};
use super::super::{AgentPool, StoryAgent};

impl AgentPool {
    /// Pipeline advancement: after an agent completes, move the story to
    /// the next pipeline stage and start the appropriate agent.
    #[allow(clippy::too_many_arguments)]
    pub(super) async fn run_pipeline_advance(
        &self,
        story_id: &str,
        agent_name: &str,
        completion: CompletionReport,
        project_root: Option<PathBuf>,
        worktree_path: Option<PathBuf>,
        merge_failure_reported: bool,
        previous_session_id: Option<String>,
    ) {
        let project_root = match project_root {
            Some(p) => p,
            None => {
                slog_warn!("[pipeline] No project_root for '{story_id}:{agent_name}'");
                return;
            }
        };

        let config = ProjectConfig::load(&project_root).unwrap_or_default();
        let stage = config
            .find_agent(agent_name)
            .map(agent_config_stage)
            .unwrap_or_else(|| pipeline_stage(agent_name));

        match stage {
            PipelineStage::Other => {
                // Supervisors and unknown agents do not advance the pipeline.
            }
            PipelineStage::Coder => {
                if completion.gates_passed {
                    // Determine effective QA mode for this story.
                    let qa_mode = {
                        let item_type = crate::agents::lifecycle::item_type_from_id(story_id);
                        if item_type == "spike" {
                            crate::io::story_metadata::QaMode::Human
                        } else {
                            let default_qa = config.default_qa_mode();
                            resolve_qa_mode_from_store(&project_root, story_id, default_qa)
                        }
                    };

                    match qa_mode {
                        crate::io::story_metadata::QaMode::Server => {
                            slog!(
                                "[pipeline] Coder '{agent_name}' passed gates for '{story_id}'. \
                                 qa: server — moving directly to merge."
                            );
                            if let Err(e) =
                                crate::agents::lifecycle::move_story_to_merge(&project_root, story_id)
                            {
                                slog_error!(
                                    "[pipeline] Failed to move '{story_id}' to 4_merge/: {e}"
                                );
                            } else {
                                self.start_mergemaster_or_block(&project_root, story_id).await;
                            }
                        }
                        crate::io::story_metadata::QaMode::Agent => {
                            slog!(
                                "[pipeline] Coder '{agent_name}' passed gates for '{story_id}'. \
                                 qa: agent — moving to QA."
                            );
                            if let Err(e) = crate::agents::lifecycle::move_story_to_qa(&project_root, story_id) {
                                slog_error!("[pipeline] Failed to move '{story_id}' to 3_qa/: {e}");
                            } else if let Err(e) = self
                                .start_agent(&project_root, story_id, Some("qa"), None, None)
                                .await
                            {
                                slog_error!("[pipeline] Failed to start qa agent for '{story_id}': {e}");
                            }
                        }
                        crate::io::story_metadata::QaMode::Human => {
                            slog!(
                                "[pipeline] Coder '{agent_name}' passed gates for '{story_id}'. \
                                 qa: human — holding for human review."
                            );
                            if let Err(e) = crate::agents::lifecycle::move_story_to_qa(&project_root, story_id) {
                                slog_error!("[pipeline] Failed to move '{story_id}' to 3_qa/: {e}");
                            } else {
                                write_review_hold_to_store(story_id);
                            }
                        }
                    }
                } else {
                    // Increment retry count and check if blocked.
                    if let Some(reason) = should_block_story(story_id, config.max_retries, "coder") {
                        // Story has exceeded retry limit — do not restart.
                        let _ = self.watcher_tx.send(WatcherEvent::StoryBlocked {
                            story_id: story_id.to_string(),
                            reason,
                        });
                    } else {
                        slog!(
                            "[pipeline] Coder '{agent_name}' failed gates for '{story_id}'. Restarting."
                        );
                        let context = format!(
                            "\n\n---\n## Previous Attempt Failed\n\
                             The acceptance gates failed with the following output:\n{}\n\n\
                             Please review the failures above, fix the issues, and try again.",
                            completion.gate_output
                        );
                        if let Err(e) = self
                            .start_agent(
                                &project_root,
                                story_id,
                                Some(agent_name),
                                Some(&context),
                                previous_session_id,
                            )
                            .await
                        {
                            slog_error!(
                                "[pipeline] Failed to restart coder '{agent_name}' for '{story_id}': {e}"
                            );
                        }
                    }
                }
            }
            PipelineStage::Qa => {
                if completion.gates_passed {
                    // Run coverage gate in the QA worktree before advancing to merge.
                    let coverage_path = worktree_path
                        .clone()
                        .unwrap_or_else(|| project_root.clone());
                    let cp = coverage_path.clone();
                    let coverage_result =
                        tokio::task::spawn_blocking(move || crate::agents::gates::run_coverage_gate(&cp))
                            .await
                            .unwrap_or_else(|e| {
                                slog_warn!("[pipeline] Coverage gate task panicked: {e}");
                                Ok((false, format!("Coverage gate task panicked: {e}")))
                            });
                    let (coverage_passed, coverage_output) = match coverage_result {
                        Ok(pair) => pair,
                        Err(e) => (false, e),
                    };

                    if coverage_passed {
                        // Check whether this item needs human review before merging.
                        let needs_human_review = {
                            let item_type = crate::agents::lifecycle::item_type_from_id(story_id);
                            if item_type == "spike" {
                                true // Spikes always need human review.
                            } else {
                                let default_qa = config.default_qa_mode();
                                matches!(
                                    resolve_qa_mode_from_store(&project_root, story_id, default_qa),
                                    crate::io::story_metadata::QaMode::Human
                                )
                            }
                        };

                        if needs_human_review {
                            // Hold in 3_qa/ for human review.
                            write_review_hold_to_store(story_id);
                            slog!(
                                "[pipeline] QA passed for '{story_id}'. \
                                 Holding for human review. \
                                 Worktree preserved at: {worktree_path:?}"
                            );
                        } else {
                            slog!(
                                "[pipeline] QA passed gates and coverage for '{story_id}'. \
                                 Moving directly to merge."
                            );
                            if let Err(e) =
                                crate::agents::lifecycle::move_story_to_merge(&project_root, story_id)
                            {
                                slog_error!(
                                    "[pipeline] Failed to move '{story_id}' to 4_merge/: {e}"
                                );
                            } else {
                                self.start_mergemaster_or_block(&project_root, story_id).await;
                            }
                        }
                    } else if let Some(reason) = should_block_story(story_id, config.max_retries, "qa-coverage") {
                        // Story has exceeded retry limit — do not restart.
                        let _ = self.watcher_tx.send(WatcherEvent::StoryBlocked {
                            story_id: story_id.to_string(),
                            reason,
                        });
                    } else {
                        slog!(
                            "[pipeline] QA coverage gate failed for '{story_id}'. Restarting QA."
                        );
                        let context = format!(
                            "\n\n---\n## Coverage Gate Failed\n\
                             The coverage gate (script/test_coverage) failed with the following output:\n{}\n\n\
                             Please improve test coverage until the coverage gate passes.",
                            coverage_output
                        );
                        if let Err(e) = self
                            .start_agent(&project_root, story_id, Some("qa"), Some(&context), None)
                            .await
                        {
                            slog_error!("[pipeline] Failed to restart qa for '{story_id}': {e}");
                        }
                    }
                } else if let Some(reason) = should_block_story(story_id, config.max_retries, "qa") {
                    // Story has exceeded retry limit — do not restart.
                    let _ = self.watcher_tx.send(WatcherEvent::StoryBlocked {
                        story_id: story_id.to_string(),
                        reason,
                    });
                } else {
                    slog!("[pipeline] QA failed gates for '{story_id}'. Restarting.");
                    let context = format!(
                        "\n\n---\n## Previous QA Attempt Failed\n\
                         The acceptance gates failed with the following output:\n{}\n\n\
                         Please re-run and fix the issues.",
                        completion.gate_output
                    );
                    if let Err(e) = self
                        .start_agent(&project_root, story_id, Some("qa"), Some(&context), None)
                        .await
                    {
                        slog_error!("[pipeline] Failed to restart qa for '{story_id}': {e}");
                    }
                }
            }
            PipelineStage::Mergemaster => {
                // Bug 529: Guard against stale mergemaster advances.  If the story
                // has already reached done or archived (e.g. a previous mergemaster
                // succeeded), this advance is a zombie — skip it entirely to avoid
                // phantom notifications and redundant post-merge test runs.
                if let Ok(Some(typed_item)) = crate::pipeline_state::read_typed(story_id) {
                    let current_dir = typed_item.stage.dir_name();
                    if current_dir == "5_done" || current_dir == "6_archived" {
                        slog!(
                            "[pipeline] Skipping stale mergemaster advance for '{story_id}': \
                             story is already in work/{current_dir}/"
                        );
                        // Skip pipeline advancement — do not run post-merge tests,
                        // do not emit notifications, do not restart agents.
                        return;
                    }
                }

                // Block advancement if the mergemaster explicitly reported a failure.
                // The server-owned gate check runs in the feature-branch worktree (not
                // master), so `gates_passed=true` is misleading when no code was merged.
                if merge_failure_reported {
                    slog!(
                        "[pipeline] Pipeline advancement blocked for '{story_id}': \
                         mergemaster explicitly reported a merge failure. \
                         Story stays in 4_merge/ for human review."
                    );
                } else {
                    // Run script/test on master (project_root) as the post-merge verification.
                    slog!(
                        "[pipeline] Mergemaster completed for '{story_id}'. Running post-merge tests on master."
                    );
                    let root = project_root.clone();
                    let test_result =
                        tokio::task::spawn_blocking(move || crate::agents::gates::run_project_tests(&root))
                            .await
                            .unwrap_or_else(|e| {
                                slog_warn!("[pipeline] Post-merge test task panicked: {e}");
                                Ok((false, format!("Test task panicked: {e}")))
                            });
                    let (passed, output) = match test_result {
                        Ok(pair) => pair,
                        Err(e) => (false, e),
                    };

                    if passed {
                        slog!(
                            "[pipeline] Post-merge tests passed for '{story_id}'. Moving to done."
                        );
                        if let Err(e) =
                            crate::agents::lifecycle::move_story_to_done(&project_root, story_id)
                        {
                            slog_error!("[pipeline] Failed to move '{story_id}' to done: {e}");
                        }
                        self.remove_agents_for_story(story_id);
                        // TODO: Re-enable worktree cleanup once we have persistent agent logs.
                        // Removing worktrees destroys evidence needed to debug empty-commit agents.
                        // let config =
                        //     crate::config::ProjectConfig::load(&project_root).unwrap_or_default();
                        // if let Err(e) =
                        //     worktree::remove_worktree_by_story_id(&project_root, story_id, &config)
                        //         .await
                        // {
                        //     slog!(
                        //         "[pipeline] Failed to remove worktree for '{story_id}': {e}"
                        //     );
                        // }
                        slog!(
                            "[pipeline] Story '{story_id}' done. Worktree preserved for inspection."
                        );
                    } else if let Some(reason) = should_block_story(story_id, config.max_retries, "mergemaster") {
                        // Story has exceeded retry limit — do not restart.
                        let _ = self.watcher_tx.send(WatcherEvent::StoryBlocked {
                            story_id: story_id.to_string(),
                            reason,
                        });
                    } else {
                        slog!(
                            "[pipeline] Post-merge tests failed for '{story_id}'. Restarting mergemaster."
                        );
                        let context = format!(
                            "\n\n---\n## Post-Merge Test Failed\n\
                         The tests on master failed with the following output:\n{}\n\n\
                         Please investigate and resolve the failures, then call merge_agent_work again.",
                            output
                        );
                        if let Err(e) = self
                            .start_agent(
                                &project_root,
                                story_id,
                                Some("mergemaster"),
                                Some(&context),
                                None,
                            )
                            .await
                        {
                            slog_error!(
                                "[pipeline] Failed to restart mergemaster for '{story_id}': {e}"
                            );
                        }
                    }
                }
            }
        }

        // Always scan for unassigned work after any agent completes, regardless
        // of the outcome (success, failure, restart).  This ensures stories that
        // failed agent assignment due to busy agents are retried when agents
        // become available (bug 295).
        self.auto_assign_available_work(&project_root).await;
    }

    /// Start the mergemaster agent for `story_id`, but only if the feature
    /// branch has commits that are not yet on master.
    ///
    /// If the branch has zero commits ahead of master, this logs an error and
    /// sends a [`WatcherEvent::StoryBlocked`] instead of spawning a Claude
    /// session.  A no-op merge session was observed spending $0.82 in the
    /// 2026-04-09 incident (story 519).
    async fn start_mergemaster_or_block(&self, project_root: &Path, story_id: &str) {
        let branch = format!("feature/story-{story_id}");
        if !crate::agents::lifecycle::feature_branch_has_unmerged_changes(project_root, story_id) {
            slog_error!(
                "[mergemaster] Branch '{branch}' has no commits ahead of master — \
                 refusing to spawn merge session. \
                 Likely cause: the worktree was reset to master after the feature \
                 branch's commits were created. Investigate the worktree's git state \
                 before retrying. Story '{story_id}' stays in 4_merge/ for human review."
            );
            let _ = self.watcher_tx.send(WatcherEvent::StoryBlocked {
                story_id: story_id.to_string(),
                reason: format!(
                    "Feature branch '{branch}' has no commits ahead of master — nothing to merge. \
                     The worktree may have been reset to master. \
                     Check the worktree's git state and retry manually."
                ),
            });
            return;
        }
        if let Err(e) = self
            .start_agent(project_root, story_id, Some("mergemaster"), None, None)
            .await
        {
            slog_error!("[pipeline] Failed to start mergemaster for '{story_id}': {e}");
        }
    }
}

/// Spawn pipeline advancement as a background task.
///
/// This is a **non-async** function so it does not participate in the opaque
/// type cycle between `start_agent` and `run_server_owned_completion`.
#[allow(clippy::too_many_arguments)]
pub(super) fn spawn_pipeline_advance(
    agents: Arc<Mutex<HashMap<String, StoryAgent>>>,
    port: u16,
    story_id: &str,
    agent_name: &str,
    completion: CompletionReport,
    project_root: Option<PathBuf>,
    worktree_path: Option<PathBuf>,
    watcher_tx: broadcast::Sender<WatcherEvent>,
    merge_failure_reported: bool,
    previous_session_id: Option<String>,
) {
    let sid = story_id.to_string();
    let aname = agent_name.to_string();
    tokio::spawn(async move {
        let pool = AgentPool {
            agents,
            port,
            child_killers: Arc::new(Mutex::new(HashMap::new())),
            watcher_tx,
            merge_jobs: Arc::new(Mutex::new(HashMap::new())),
        };
        pool.run_pipeline_advance(
            &sid,
            &aname,
            completion,
            project_root,
            worktree_path,
            merge_failure_reported,
            previous_session_id,
        )
        .await;
    });
}

/// Resolve QA mode from the content store.
fn resolve_qa_mode_from_store(
    _project_root: &Path,
    story_id: &str,
    default: crate::io::story_metadata::QaMode,
) -> crate::io::story_metadata::QaMode {
    if let Some(contents) = crate::db::read_content(story_id) {
        return crate::io::story_metadata::resolve_qa_mode_from_content(&contents, default);
    }
    default
}

/// Write review_hold to the content store.
fn write_review_hold_to_store(story_id: &str) {
    if let Some(contents) = crate::db::read_content(story_id) {
        let updated = crate::io::story_metadata::write_review_hold_in_content(&contents);
        crate::db::write_content(story_id, &updated);
        // Also persist to SQLite via shadow write.
        let stage = crate::pipeline_state::read_typed(story_id)
            .ok()
            .flatten()
            .map(|i| i.stage.dir_name().to_string())
            .unwrap_or_else(|| "3_qa".to_string());
        crate::db::write_item_with_content(story_id, &stage, &updated);
    } else {
        slog_error!("[pipeline] Cannot write review_hold for '{story_id}': no content in store");
    }
}

/// Increment retry_count and block the story if it exceeds `max_retries`.
///
/// Returns `Some(reason)` if the story is now blocked (caller should NOT restart the agent).
/// Returns `None` if the story may be retried.
/// When `max_retries` is 0, retry limits are disabled.
fn should_block_story(story_id: &str, max_retries: u32, stage_label: &str) -> Option<String> {
    use crate::io::story_metadata::{increment_retry_count_in_content, write_blocked_in_content};

    if max_retries == 0 {
        return None;
    }

    if let Some(contents) = crate::db::read_content(story_id) {
        let (updated, new_count) = increment_retry_count_in_content(&contents);
        crate::db::write_content(story_id, &updated);
        let stage = crate::pipeline_state::read_typed(story_id)
            .ok()
            .flatten()
            .map(|i| i.stage.dir_name().to_string())
            .unwrap_or_else(|| "2_current".to_string());
        crate::db::write_item_with_content(story_id, &stage, &updated);

        if new_count >= max_retries {
            slog_warn!(
                "[pipeline] Story '{story_id}' reached retry limit ({new_count}/{max_retries}) \
                 at {stage_label} stage. Marking as blocked."
            );
            let blocked = write_blocked_in_content(&updated);
            crate::db::write_content(story_id, &blocked);
            crate::db::write_item_with_content(story_id, &stage, &blocked);
            Some(format!(
                "Retry limit exceeded ({new_count}/{max_retries}) at {stage_label} stage"
            ))
        } else {
            slog!(
                "[pipeline] Story '{story_id}' retry {new_count}/{max_retries} at {stage_label} stage."
            );
            None
        }
    } else {
        slog_error!("[pipeline] Failed to read content for '{story_id}' to increment retry_count");
        None
    }
}

#[cfg(test)]
mod tests {
    use super::super::super::AgentPool;
    use super::super::super::composite_key;
    use crate::agents::{AgentStatus, CompletionReport};
    use crate::io::watcher::WatcherEvent;

    // ── pipeline advance tests ────────────────────────────────────────────────

    #[tokio::test]
    async fn pipeline_advance_coder_gates_pass_server_qa_moves_to_merge() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();

        // Set up story in 2_current/ (no qa frontmatter → uses project default "server").
        // Use a unique high-numbered ID to avoid collision with the agent_qa test.
        let current = root.join(".huskies/work/2_current");
        fs::create_dir_all(&current).unwrap();
        fs::write(current.join("9908_story_server_qa.md"), "test").unwrap();
        crate::db::ensure_content_store();
        crate::db::write_content("9908_story_server_qa", "test");

        let pool = AgentPool::new_test(3001);
        pool.run_pipeline_advance(
            "9908_story_server_qa",
            "coder-1",
            CompletionReport {
                summary: "done".to_string(),
                gates_passed: true,
                gate_output: String::new(),
            },
            Some(root.to_path_buf()),
            None,
            false,
            None,
        )
        .await;

        // With default qa: server, story skips QA and goes straight to 4_merge/
        // Lifecycle moves now update the content store, not the filesystem.
        assert!(
            crate::db::read_content("9908_story_server_qa").is_some(),
            "story should still exist in content store after move to merge"
        );
    }

    #[tokio::test]
    async fn pipeline_advance_coder_gates_pass_agent_qa_moves_to_qa() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();

        // Set up story in 2_current/ with qa: agent frontmatter.
        // Use a unique high-numbered ID to avoid collision with the server_qa test.
        let current = root.join(".huskies/work/2_current");
        fs::create_dir_all(&current).unwrap();
        fs::write(
            current.join("9909_story_agent_qa.md"),
            "---\nname: Test\nqa: agent\n---\ntest",
        )
        .unwrap();
        crate::db::ensure_content_store();
        crate::db::write_content("9909_story_agent_qa", "---\nname: Test\nqa: agent\n---\ntest");

        let pool = AgentPool::new_test(3001);
        pool.run_pipeline_advance(
            "9909_story_agent_qa",
            "coder-1",
            CompletionReport {
                summary: "done".to_string(),
                gates_passed: true,
                gate_output: String::new(),
            },
            Some(root.to_path_buf()),
            None,
            false,
            None,
        )
        .await;

        // With qa: agent, story should move to 3_qa/
        // Lifecycle moves now update the content store, not the filesystem.
        assert!(
            crate::db::read_content("9909_story_agent_qa").is_some(),
            "story should still exist in content store after move to qa"
        );
    }

    #[tokio::test]
    async fn pipeline_advance_qa_gates_pass_moves_story_to_merge() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();

        // Set up story in 3_qa/
        let qa_dir = root.join(".huskies/work/3_qa");
        fs::create_dir_all(&qa_dir).unwrap();
        // qa: server so the story skips human review and goes straight to merge.
        fs::write(
            qa_dir.join("51_story_test.md"),
            "---\nname: Test\nqa: server\n---\ntest",
        )
        .unwrap();
        crate::db::ensure_content_store();
        crate::db::write_content("51_story_test", "---\nname: Test\nqa: server\n---\ntest");

        let pool = AgentPool::new_test(3001);
        pool.run_pipeline_advance(
            "51_story_test",
            "qa",
            CompletionReport {
                summary: "QA done".to_string(),
                gates_passed: true,
                gate_output: String::new(),
            },
            Some(root.to_path_buf()),
            None,
            false,
            None,
        )
        .await;

        // Story should have moved to 4_merge/
        // Lifecycle moves now update the content store, not the filesystem.
        assert!(
            crate::db::read_content("51_story_test").is_some(),
            "story should still exist in content store after move to merge"
        );
    }

    #[tokio::test]
    async fn pipeline_advance_supervisor_does_not_advance() {
        use std::fs;
        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();

        let current = root.join(".huskies/work/2_current");
        fs::create_dir_all(&current).unwrap();
        fs::write(current.join("52_story_test.md"), "test").unwrap();

        let pool = AgentPool::new_test(3001);
        pool.run_pipeline_advance(
            "52_story_test",
            "supervisor",
            CompletionReport {
                summary: "supervised".to_string(),
                gates_passed: true,
                gate_output: String::new(),
            },
            Some(root.to_path_buf()),
            None,
            false,
            None,
        )
        .await;

        // Story should NOT have moved (supervisors don't advance pipeline)
        assert!(
            current.join("52_story_test.md").exists(),
            "story should still be in 2_current/ for supervisor"
        );
    }

    #[tokio::test]
    async fn pipeline_advance_sends_agent_state_changed_to_watcher_tx() {
        use std::fs;

        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();

        // Set up story in 2_current/
        let current = root.join(".huskies/work/2_current");
        fs::create_dir_all(&current).unwrap();
        fs::write(current.join("173_story_test.md"), "test").unwrap();
        // Ensure 3_qa/ exists for the move target
        fs::create_dir_all(root.join(".huskies/work/3_qa")).unwrap();
        // Ensure 1_backlog/ exists (start_agent calls move_story_to_current)
        fs::create_dir_all(root.join(".huskies/work/1_backlog")).unwrap();

        // Write a project.toml with a qa agent so start_agent can resolve it.
        fs::create_dir_all(root.join(".huskies")).unwrap();
        fs::write(
            root.join(".huskies/project.toml"),
            r#"
default_qa = "agent"

[[agent]]
name = "coder-1"
role = "Coder"
command = "echo"
args = ["noop"]
prompt = "test"
stage = "coder"

[[agent]]
name = "qa"
role = "QA"
command = "echo"
args = ["noop"]
prompt = "test"
stage = "qa"
"#,
        )
        .unwrap();

        let pool = AgentPool::new_test(3001);
        // Subscribe to the watcher channel BEFORE the pipeline advance.
        let mut rx = pool.watcher_tx.subscribe();

        pool.run_pipeline_advance(
            "173_story_test",
            "coder-1",
            CompletionReport {
                summary: "done".to_string(),
                gates_passed: true,
                gate_output: String::new(),
            },
            Some(root.to_path_buf()),
            None,
            false,
            None,
        )
        .await;

        // The pipeline advance should have sent AgentStateChanged events via
        // the pool's watcher_tx (not a dummy channel). Collect all events.
        let mut got_agent_state_changed = false;
        while let Ok(evt) = rx.try_recv() {
            if matches!(evt, WatcherEvent::AgentStateChanged) {
                got_agent_state_changed = true;
                break;
            }
        }

        assert!(
            got_agent_state_changed,
            "pipeline advance should send AgentStateChanged through the real watcher_tx \
             (bug 173: lozenges must update when agents are assigned during pipeline advance)"
        );
    }

    // ── story 519: mergemaster pre-flight blocks when no commits ahead ──

    /// Regression test for story 519: when the feature branch has zero commits
    /// ahead of master, mergemaster must not spawn a Claude session.  A no-op
    /// session spent $0.82 in the 2026-04-09 incident because the worktree was
    /// reset to master before mergemaster ran.
    #[tokio::test]
    async fn mergemaster_blocks_and_sends_story_blocked_when_no_commits_ahead() {
        use std::fs;
        use std::process::Command;

        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();

        // Init a bare git repo on master with one empty commit.
        Command::new("git").args(["init"]).current_dir(root).output().unwrap();
        Command::new("git").args(["config", "user.email", "test@test.com"]).current_dir(root).output().unwrap();
        Command::new("git").args(["config", "user.name", "Test"]).current_dir(root).output().unwrap();
        Command::new("git").args(["commit", "--allow-empty", "-m", "init"]).current_dir(root).output().unwrap();

        // Create a feature branch that points at master HEAD (zero commits ahead).
        // This replicates the incident where the worktree was reset to master.
        Command::new("git")
            .args(["branch", "feature/story-9919_story_no_commits"])
            .current_dir(root)
            .output()
            .unwrap();

        // Set up pipeline dirs and story file.
        let current = root.join(".huskies/work/2_current");
        fs::create_dir_all(&current).unwrap();
        fs::create_dir_all(root.join(".huskies/work/4_merge")).unwrap();
        fs::write(current.join("9919_story_no_commits.md"), "---\nname: Test\n---\n").unwrap();
        crate::db::ensure_content_store();
        crate::db::write_content("9919_story_no_commits", "---\nname: Test\n---\n");

        let pool = AgentPool::new_test(3001);
        let mut rx = pool.watcher_tx.subscribe();

        // Simulate coder completing with gates passed (qa: server → goes to merge).
        pool.run_pipeline_advance(
            "9919_story_no_commits",
            "coder-1",
            CompletionReport {
                summary: "done".to_string(),
                gates_passed: true,
                gate_output: String::new(),
            },
            Some(root.to_path_buf()),
            None,
            false,
            None,
        )
        .await;

        // Story should still exist in the content store after moving to merge.
        assert!(
            crate::db::read_content("9919_story_no_commits").is_some(),
            "story should remain in content store — not removed"
        );

        // A StoryBlocked event must have been emitted (triggers chat failure notice,
        // not the success 🎉 emoji).
        let mut got_blocked = false;
        while let Ok(evt) = rx.try_recv() {
            if let WatcherEvent::StoryBlocked { story_id, .. } = &evt
                && story_id == "9919_story_no_commits"
            {
                got_blocked = true;
                break;
            }
        }
        assert!(
            got_blocked,
            "StoryBlocked event must be sent when feature branch has no commits ahead of master"
        );

        // No mergemaster agent should have been started.
        let agents = pool.agents.lock().unwrap();
        let mergemaster_started = agents
            .values()
            .any(|a| a.agent_name.contains("mergemaster"));
        assert!(
            !mergemaster_started,
            "mergemaster agent must NOT be started when no commits ahead of master"
        );
    }

    // ── bug 295: pipeline advance picks up waiting QA stories ──────────

    #[tokio::test]
    async fn pipeline_advance_picks_up_waiting_qa_stories_after_completion() {
        use std::fs;
        use super::super::super::auto_assign::is_agent_free;

        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();

        let sk = root.join(".huskies");
        let qa_dir = sk.join("work/3_qa");
        fs::create_dir_all(&qa_dir).unwrap();

        // Configure a single QA agent.
        fs::write(
            sk.join("project.toml"),
            r#"
[[agent]]
name = "qa"
stage = "qa"
"#,
        )
        .unwrap();

        // Story 292 is in QA with QA agent running (will "complete" via
        // run_pipeline_advance below).  Story 293 is in QA with NO agent —
        // simulating the "stuck" state from bug 295.
        fs::write(
            qa_dir.join("292_story_first.md"),
            "---\nname: First\nqa: human\n---\n",
        )
        .unwrap();
        fs::write(
            qa_dir.join("293_story_second.md"),
            "---\nname: Second\nqa: human\n---\n",
        )
        .unwrap();

        let pool = AgentPool::new_test(3001);
        // QA is currently running on story 292.
        pool.inject_test_agent("292_story_first", "qa", AgentStatus::Running);

        // Verify that 293 cannot get a QA agent right now (QA is busy).
        {
            let agents = pool.agents.lock().unwrap();
            assert!(
                !is_agent_free(&agents, "qa"),
                "qa should be busy on story 292"
            );
        }

        // Simulate QA completing on story 292: remove the agent from the pool
        // (as run_server_owned_completion does) then run pipeline advance.
        {
            let mut agents = pool.agents.lock().unwrap();
            agents.remove(&composite_key("292_story_first", "qa"));
        }

        pool.run_pipeline_advance(
            "292_story_first",
            "qa",
            CompletionReport {
                summary: "QA done".to_string(),
                gates_passed: true,
                gate_output: String::new(),
            },
            Some(root.to_path_buf()),
            None,
            false,
            None,
        )
        .await;

        // After pipeline advance, auto_assign should have started QA on story 293.
        let agents = pool.agents.lock().unwrap();
        let qa_on_293 = agents.values().any(|a| {
            a.agent_name == "qa"
                && matches!(a.status, AgentStatus::Pending | AgentStatus::Running)
        });
        assert!(
            qa_on_293,
            "auto_assign should have started qa for story 293 after 292's QA completed, \
             but no qa agent is pending/running. Pool: {:?}",
            agents
                .iter()
                .map(|(k, a)| format!("{k}: {} ({})", a.agent_name, a.status))
                .collect::<Vec<_>>()
        );
    }

    // ── bug 529: stale mergemaster advance for a done story is a no-op ──

    /// Regression test for bug 529: when a stale mergemaster advance fires
    /// after the story has already reached 5_done, the advance must be a
    /// no-op — no post-merge tests, no notifications, no agent restarts.
    #[tokio::test]
    async fn stale_mergemaster_advance_for_done_story_is_noop() {
        use std::fs;
        use std::process::Command;

        // Initialise CRDT so read_typed works.
        crate::crdt_state::init_for_test();
        crate::db::ensure_content_store();

        let tmp = tempfile::tempdir().unwrap();
        let root = tmp.path();

        // Init a git repo so post-merge tests would pass if they ran.
        Command::new("git").args(["init"]).current_dir(root).output().unwrap();
        Command::new("git").args(["config", "user.email", "test@test.com"]).current_dir(root).output().unwrap();
        Command::new("git").args(["config", "user.name", "Test"]).current_dir(root).output().unwrap();
        Command::new("git").args(["commit", "--allow-empty", "-m", "init"]).current_dir(root).output().unwrap();

        // Set up pipeline dirs.
        fs::create_dir_all(root.join(".huskies/work/5_done")).unwrap();

        // Seed the story in 5_done via the DB, which also writes to the CRDT.
        let story_id = "9929_story_zombie_merge";
        let content = "---\nname: Zombie Merge Test\n---\n";
        crate::db::write_content(story_id, content);
        crate::db::write_item_with_content(story_id, "5_done", content);

        let pool = AgentPool::new_test(3001);
        let mut rx = pool.watcher_tx.subscribe();

        // Simulate a stale mergemaster advance firing for the already-done story.
        pool.run_pipeline_advance(
            story_id,
            "mergemaster",
            CompletionReport {
                summary: "stale advance".to_string(),
                gates_passed: true,
                gate_output: String::new(),
            },
            Some(root.to_path_buf()),
            None,
            false,
            None,
        )
        .await;

        // No agents should have been started.
        let agents = pool.agents.lock().unwrap();
        assert!(
            agents.is_empty(),
            "No agents should be started for a stale advance on a done story. \
             Pool: {:?}",
            agents.keys().collect::<Vec<_>>()
        );
        drop(agents);

        // No StoryBlocked or other events should have been emitted.
        let mut got_event = false;
        while let Ok(evt) = rx.try_recv() {
            // AgentStateChanged from auto_assign is acceptable only if the
            // advance didn't short-circuit.  Since we return early, no events.
            if matches!(evt, WatcherEvent::StoryBlocked { .. }) {
                got_event = true;
            }
        }
        assert!(
            !got_event,
            "No StoryBlocked event should be emitted for a stale advance"
        );

        // The story should still be in 5_done (not moved elsewhere).
        if let Ok(Some(item)) = crate::pipeline_state::read_typed(story_id) {
            assert_eq!(
                item.stage.dir_name(),
                "5_done",
                "Story should remain in 5_done after stale mergemaster advance"
            );
        }
    }
}