huskies: merge 913

server/src/agents/lifecycle.rs

@@ -12,8 +12,8 @@ use std::process::Command;
 
 use crate::db::yaml_legacy::clear_front_matter_field_in_content;
 use crate::pipeline_state::{
-    ApplyError, ArchiveReason, BranchName, GitSha, PipelineEvent, Stage, apply_transition,
-    stage_label,
+    ApplyError, ArchiveReason, BranchName, GitSha, PipelineEvent, Stage, TransitionFired,
+    apply_transition, stage_label,
 };
 use crate::slog;
 
@@ -248,13 +248,22 @@ pub fn transition_to_blocked(story_id: &str, reason: &str) -> Result<(), String>
     .map_err(|e| e.to_string())
 }
 
-/// Transition a story from `Stage::Merge` to `Stage::MergeFailure` via the state machine.
+/// Transition a story from `Stage::Merge` (or `Stage::MergeFailure`) to
+/// `Stage::MergeFailure` via the state machine.
 ///
 /// Builds a `PipelineEvent::MergeFailed { reason }`, validates the transition, writes
 /// the resulting `Stage::MergeFailure` to the CRDT, and persists the reason to front
 /// matter so it survives server restarts.
+///
+/// When the story is already in `MergeFailure`, this is a silent self-loop: the
+/// returned `TransitionFired::before` will be `Stage::MergeFailure`.  Callers
+/// should suppress re-notification in that case to avoid duplicate chat messages.
+///
 /// Returns `Err` on `TransitionError` — callers must NOT fall back to direct register writes.
-pub fn transition_to_merge_failure(story_id: &str, reason: &str) -> Result<(), String> {
+pub fn transition_to_merge_failure(
+    story_id: &str,
+    reason: &str,
+) -> Result<TransitionFired, String> {
     let reason_owned = reason.to_string();
     let transform: Box<dyn Fn(&str) -> String> = Box::new(move |content: &str| {
         crate::db::yaml_legacy::write_merge_failure_in_content(content, &reason_owned)
@@ -266,7 +275,6 @@ pub fn transition_to_merge_failure(story_id: &str, reason: &str) -> Result<(), S
         },
         Some(&*transform),
     )
-    .map(|_| ())
     .map_err(|e| e.to_string())
 }
 

server/src/agents/pool/pipeline/merge/runner.rs

@@ -126,21 +126,32 @@ impl AgentPool {
                         });
                 } else {
                     // Transition through the state machine (Merge → MergeFailure).
-                    if let Err(e) =
-                        crate::agents::lifecycle::transition_to_merge_failure(&sid, &reason)
-                    {
+                    // Only send the notification when the stage actually changed; if the
+                    // story was already in MergeFailure (self-loop), suppress the duplicate.
+                    let should_notify = match crate::agents::lifecycle::transition_to_merge_failure(
+                        &sid, &reason,
+                    ) {
+                        Ok(fired) => !matches!(
+                            fired.before,
+                            crate::pipeline_state::Stage::MergeFailure { .. }
+                        ),
+                        Err(e) => {
                             crate::slog_error!(
                                 "[merge] Failed to transition '{sid}' to MergeFailure: {e}"
                             );
+                            true
                         }
-                    let _ = pool
-                        .watcher_tx
+                    };
+                    if should_notify {
+                        let _ =
+                            pool.watcher_tx
                                 .send(crate::io::watcher::WatcherEvent::MergeFailure {
                                     story_id: sid.clone(),
                                     reason,
                                 });
                     }
                 }
+            }
 
             // Update CRDT with terminal status.
             match &report {

server/src/http/mcp/merge_tools.rs

@@ -179,19 +179,28 @@ pub(super) fn tool_report_merge_failure(args: &Value, ctx: &AppContext) -> Resul
     slog!("[mergemaster] Merge failure reported for '{story_id}': {reason}");
     ctx.services.agents.set_merge_failure_reported(story_id);
 
-    // Broadcast the failure so the Matrix notification listener can post an
-    // error message to configured rooms without coupling this tool to the bot.
+    // Route the failure through the typed state machine (Merge → MergeFailure).
+    // This persists the reason in front matter and updates the CRDT stage.
+    // Only broadcast the notification when the stage actually changed; if the
+    // story was already in MergeFailure (self-loop), suppress the duplicate.
+    let should_notify =
+        match crate::agents::lifecycle::transition_to_merge_failure(story_id, reason) {
+            Ok(fired) => !matches!(
+                fired.before,
+                crate::pipeline_state::Stage::MergeFailure { .. }
+            ),
+            Err(e) => {
+                slog_warn!("[mergemaster] Failed to transition '{story_id}' to MergeFailure: {e}");
+                true
+            }
+        };
+    if should_notify {
         let _ = ctx
             .watcher_tx
             .send(crate::io::watcher::WatcherEvent::MergeFailure {
                 story_id: story_id.to_string(),
                 reason: reason.to_string(),
             });
-
-    // Route the failure through the typed state machine (Merge → MergeFailure).
-    // This persists the reason in front matter and updates the CRDT stage.
-    if let Err(e) = crate::agents::lifecycle::transition_to_merge_failure(story_id, reason) {
-        slog_warn!("[mergemaster] Failed to transition '{story_id}' to MergeFailure: {e}");
     }
 
     Ok(format!(

server/src/pipeline_state/tests.rs

@@ -750,4 +750,82 @@ fn merge_failure_transition_emits_event_with_full_reason() {
     );
 }
 
+// ── Story 913: MergeFailure + MergeFailed self-loop ────────────────
+
+/// AC1: `MergeFailure + MergeFailed` is a valid self-transition — no error logged.
+#[test]
+fn merge_failure_plus_merge_failed_is_self_loop() {
+    let s = Stage::MergeFailure {
+        reason: "initial failure".into(),
+    };
+    let result = transition(
+        s,
+        PipelineEvent::MergeFailed {
+            reason: "second failure".into(),
+        },
+    );
+    assert!(
+        matches!(result, Ok(Stage::MergeFailure { .. })),
+        "MergeFailure + MergeFailed should self-loop to MergeFailure, got: {result:?}"
+    );
+}
+
+/// AC2 + AC3: applying `MergeFailed` to a story already in `MergeFailure` succeeds and
+/// the `TransitionFired::before` is `MergeFailure`, allowing callers to suppress the
+/// duplicate notification.
+#[test]
+fn repeated_merge_failure_apply_transition_no_error_no_duplicate_notification() {
+    crate::crdt_state::init_for_test();
+    crate::db::ensure_content_store();
+
+    let story_id = "99913_story_merge_failure_selfloop";
+    crate::db::write_item_with_content(
+        story_id,
+        "4_merge_failure",
+        "---\nname: MergeFailure Self-loop Test\n---\n# Story\n",
+        crate::db::ItemMeta::from_yaml("---\nname: MergeFailure Self-loop Test\n---\n# Story\n"),
+    );
+
+    // Apply a second MergeFailed to a story already in MergeFailure.
+    let fired = super::apply::apply_transition(
+        story_id,
+        PipelineEvent::MergeFailed {
+            reason: "duplicate failure".into(),
+        },
+        None,
+    )
+    .expect("MergeFailed on already-failed story should succeed without error");
+
+    // The before-stage was MergeFailure: this was a self-loop.
+    // Callers check this to decide whether to suppress the chat notification.
+    assert!(
+        matches!(fired.before, Stage::MergeFailure { .. }),
+        "fired.before should be MergeFailure (self-loop): {:?}",
+        fired.before
+    );
+    assert!(
+        matches!(fired.after, Stage::MergeFailure { .. }),
+        "fired.after should remain MergeFailure: {:?}",
+        fired.after
+    );
+
+    // Verify the CRDT stage is still 4_merge_failure.
+    let item = read_typed(story_id)
+        .expect("CRDT read should succeed")
+        .expect("item should still exist");
+    assert_eq!(
+        item.stage.dir_name(),
+        "4_merge_failure",
+        "CRDT stage should remain 4_merge_failure after self-loop"
+    );
+
+    // Simulate the caller's de-dup logic: since fired.before is already MergeFailure,
+    // no notification should be dispatched.
+    let should_notify = !matches!(fired.before, Stage::MergeFailure { .. });
+    assert!(
+        !should_notify,
+        "should_notify must be false for a self-loop to prevent duplicate notification"
+    );
+}
+
 // ── ProjectionError Display ─────────────────────────────────────────

server/src/pipeline_state/transition.rs

@@ -181,6 +181,12 @@ pub fn transition(state: Stage, event: PipelineEvent) -> Result<Stage, Transitio
         // ── MergeFailed: Merge → MergeFailure (recoverable intermediate) ──
         (Merge { .. }, MergeFailed { reason }) => Ok(MergeFailure { reason }),
 
+        // ── MergeFailure self-loop: repeated failure is a no-op ─────────────
+        // When the mergemaster retries and fails again while the story is already
+        // in MergeFailure, treat it as a silent self-transition so callers can
+        // detect the no-op via `fired.before == MergeFailure` and skip re-notifying.
+        (MergeFailure { .. }, MergeFailed { reason }) => Ok(MergeFailure { reason }),
+
         (Merge { .. }, MergeFailedFinal { reason }) => Ok(Archived {
             archived_at: now,
             reason: ArchiveReason::MergeFailed { reason },