Merge polecat/Ace: mq list + mq reject commands

Combined with Dag's mq retry from previous merge.
Full MQ CLI now includes: list, retry, reject subcommands.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/refinery/manager.go

@@ -551,13 +551,13 @@ Thank you for your contribution!`,
 	router.Send(msg)
 }
 
-// ErrMRNotFound is returned when a merge request is not found.
-var ErrMRNotFound = errors.New("merge request not found")
+// Common errors for MR operations
+var (
+	ErrMRNotFound  = errors.New("merge request not found")
+	ErrMRNotFailed = errors.New("merge request has not failed")
+)
 
-// ErrMRNotFailed is returned when trying to retry an MR that hasn't failed.
-var ErrMRNotFailed = errors.New("merge request has not failed")
-
-// GetMR returns a merge request by ID.
+// GetMR returns a merge request by ID from the state.
 func (m *Manager) GetMR(id string) (*MergeRequest, error) {
 	ref, err := m.loadState()
 	if err != nil {
@@ -579,6 +579,34 @@ func (m *Manager) GetMR(id string) (*MergeRequest, error) {
 	return nil, ErrMRNotFound
 }
 
+// FindMR finds a merge request by ID or branch name in the queue.
+func (m *Manager) FindMR(idOrBranch string) (*MergeRequest, error) {
+	queue, err := m.Queue()
+	if err != nil {
+		return nil, err
+	}
+
+	for _, item := range queue {
+		// Match by ID
+		if item.MR.ID == idOrBranch {
+			return item.MR, nil
+		}
+		// Match by branch name (with or without polecat/ prefix)
+		if item.MR.Branch == idOrBranch {
+			return item.MR, nil
+		}
+		if "polecat/"+idOrBranch == item.MR.Branch {
+			return item.MR, nil
+		}
+		// Match by worker name (partial match for convenience)
+		if strings.Contains(item.MR.ID, idOrBranch) {
+			return item.MR, nil
+		}
+	}
+
+	return nil, ErrMRNotFound
+}
+
 // Retry resets a failed merge request so it can be processed again.
 // If processNow is true, immediately processes the MR instead of waiting for the loop.
 func (m *Manager) Retry(id string, processNow bool) error {
@@ -635,6 +663,54 @@ func (m *Manager) RegisterMR(mr *MergeRequest) error {
 	return m.saveState(ref)
 }
 
+// RejectMR manually rejects a merge request.
+// It closes the MR with rejected status and optionally notifies the worker.
+// Returns the rejected MR for display purposes.
+func (m *Manager) RejectMR(idOrBranch string, reason string, notify bool) (*MergeRequest, error) {
+	mr, err := m.FindMR(idOrBranch)
+	if err != nil {
+		return nil, err
+	}
+
+	// Verify MR is open or in_progress (can't reject already closed)
+	if mr.IsClosed() {
+		return nil, fmt.Errorf("%w: MR is already closed with reason: %s", ErrClosedImmutable, mr.CloseReason)
+	}
+
+	// Close with rejected reason
+	if err := mr.Close(CloseReasonRejected); err != nil {
+		return nil, fmt.Errorf("failed to close MR: %w", err)
+	}
+	mr.Error = reason
+
+	// Optionally notify worker
+	if notify {
+		m.notifyWorkerRejected(mr, reason)
+	}
+
+	return mr, nil
+}
+
+// notifyWorkerRejected sends a rejection notification to a polecat.
+func (m *Manager) notifyWorkerRejected(mr *MergeRequest, reason string) {
+	router := mail.NewRouter(m.workDir)
+	msg := &mail.Message{
+		From:    fmt.Sprintf("%s/refinery", m.rig.Name),
+		To:      fmt.Sprintf("%s/%s", m.rig.Name, mr.Worker),
+		Subject: "Merge request rejected",
+		Body: fmt.Sprintf(`Your merge request has been rejected.
+
+Branch: %s
+Issue: %s
+Reason: %s
+
+Please review the feedback and address the issues before resubmitting.`,
+			mr.Branch, mr.IssueID, reason),
+		Priority: mail.PriorityNormal,
+	}
+	router.Send(msg)
+}
+
 // findTownRoot walks up directories to find the town root.
 func findTownRoot(startPath string) string {
 	path := startPath

internal/refinery/types_test.go

@@ -255,3 +255,48 @@ func TestMergeRequest_StatusChecks(t *testing.T) {
 		})
 	}
 }
+
+func TestMergeRequest_Rejection(t *testing.T) {
+	t.Run("reject from open succeeds", func(t *testing.T) {
+		mr := &MergeRequest{Status: MROpen}
+		err := mr.Close(CloseReasonRejected)
+		if err != nil {
+			t.Errorf("Close(rejected) unexpected error: %v", err)
+		}
+		if mr.Status != MRClosed {
+			t.Errorf("Close(rejected) status = %s, want %s", mr.Status, MRClosed)
+		}
+		if mr.CloseReason != CloseReasonRejected {
+			t.Errorf("Close(rejected) closeReason = %s, want %s", mr.CloseReason, CloseReasonRejected)
+		}
+	})
+
+	t.Run("reject from in_progress succeeds", func(t *testing.T) {
+		mr := &MergeRequest{Status: MRInProgress}
+		err := mr.Close(CloseReasonRejected)
+		if err != nil {
+			t.Errorf("Close(rejected) unexpected error: %v", err)
+		}
+		if mr.Status != MRClosed {
+			t.Errorf("Close(rejected) status = %s, want %s", mr.Status, MRClosed)
+		}
+		if mr.CloseReason != CloseReasonRejected {
+			t.Errorf("Close(rejected) closeReason = %s, want %s", mr.CloseReason, CloseReasonRejected)
+		}
+	})
+
+	t.Run("reject from closed fails", func(t *testing.T) {
+		mr := &MergeRequest{Status: MRClosed, CloseReason: CloseReasonMerged}
+		err := mr.Close(CloseReasonRejected)
+		if err == nil {
+			t.Error("Close(rejected) expected error, got nil")
+		}
+		if !errors.Is(err, ErrClosedImmutable) {
+			t.Errorf("Close(rejected) error = %v, want %v", err, ErrClosedImmutable)
+		}
+		// CloseReason should not change
+		if mr.CloseReason != CloseReasonMerged {
+			t.Errorf("Close(rejected) closeReason changed from %s to %s", CloseReasonMerged, mr.CloseReason)
+		}
+	})
+}