huskies: merge 1199 story Orphaned build-dir GC: reclaim dead worktree targets without touching warm caches

server/src/agents/merge/mod.rs

@@ -4,7 +4,7 @@ use serde::{Deserialize, Serialize};
 
 mod squash;
 
-pub(crate) use squash::run_squash_merge;
+pub(crate) use squash::{merge_lock_is_free, run_squash_merge};
 
 /// Typed outcome of a completed squash-merge operation.
 ///

server/src/agents/merge/squash/mod.rs

@@ -17,6 +17,19 @@ use crate::config::ProjectConfig;
 /// causing `git cherry-pick merge-queue/…` to fail with "bad revision".
 static MERGE_LOCK: Mutex<()> = Mutex::new(());
 
+/// Returns `true` when no squash-merge is currently running, i.e. the merge
+/// lock is free.
+///
+/// Used by the build-directory GC pass (story 1199) to decide whether
+/// `.huskies/merge_workspace` is safe to reclaim. This is a best-effort,
+/// momentary check — the lock is not held across the reclaim itself, so a
+/// merge that starts immediately afterward can still race with GC. That's
+/// acceptable: the GC pass tolerates races and skips on error rather than
+/// failing the whole pass.
+pub(crate) fn merge_lock_is_free() -> bool {
+    MERGE_LOCK.try_lock().is_ok()
+}
+
 /// Resolve the base branch for `project_root` from config, or auto-detect it.
 fn resolve_base_branch(project_root: &Path) -> String {
     let configured = crate::config::ProjectConfig::load(project_root)

server/src/agents/pool/worktree_lifecycle.rs

@@ -157,6 +157,12 @@ pub(crate) async fn on_coding_transition(project_root: &Path, port: u16, story_i
 }
 
 /// Remove the worktree and feature branch for `story_id` after it reaches a terminal stage.
+///
+/// Story 1199: bytes-reclaimed accounting for the worktree's `target/` dir
+/// happens one layer down, in `remove_worktree` — the single choke point
+/// shared by this subscriber, the `remove_worktree` MCP tool, and
+/// `worktree::cleanup`/`sweep`. Logging it there (once) avoids a duplicate
+/// log line here.
 pub(crate) async fn on_terminal_transition(project_root: &Path, story_id: &str) {
     let config = match crate::config::ProjectConfig::load(project_root) {
         Ok(c) => c,
@@ -270,6 +276,30 @@ mod tests {
         );
     }
 
+    /// Story 1199 AC4: on_terminal_transition reclaims the worktree's target/
+    /// dir (and everything else in the worktree) when removing it.
+    #[tokio::test]
+    async fn terminal_transition_reclaims_target_dir() {
+        let tmp = TempDir::new().unwrap();
+        let root = setup_project(&tmp);
+        let story_id = "1006_test_reclaim_target";
+
+        on_coding_transition(&root, 3001, story_id).await;
+        let wt_path = crate::worktree::worktree_path(&root, story_id);
+        let target_dir = wt_path.join("target");
+        fs::create_dir_all(&target_dir).unwrap();
+        fs::write(target_dir.join("build_artifact.bin"), vec![0u8; 512]).unwrap();
+        assert!(target_dir.exists(), "target/ must exist before cleanup");
+
+        on_terminal_transition(&root, story_id).await;
+
+        assert!(
+            !target_dir.exists(),
+            "target/ dir must be reclaimed when the worktree is removed"
+        );
+        assert!(!wt_path.exists());
+    }
+
     /// AC2: on_terminal_transition is a no-op (non-fatal) when no worktree exists.
     #[tokio::test]
     async fn terminal_transition_noop_when_no_worktree() {