feat: implement gt mq retry command for failed merge requests

Add 'gt mq retry <rig> <mr-id>' command to retry failed MRs:
- Added GetMR() and Retry() methods to refinery.Manager
- Added RegisterMR() for persistent MR tracking
- Added PendingMRs field to Refinery state
- Created new mq.go command file with retry subcommand
- Support --now flag for immediate processing
- Added comprehensive tests for retry functionality

Closes gt-svi.4

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

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

internal/refinery/manager.go

@@ -551,6 +551,90 @@ 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")
+
+// 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.
+func (m *Manager) GetMR(id string) (*MergeRequest, error) {
+	ref, err := m.loadState()
+	if err != nil {
+		return nil, err
+	}
+
+	// Check if it's the current MR
+	if ref.CurrentMR != nil && ref.CurrentMR.ID == id {
+		return ref.CurrentMR, nil
+	}
+
+	// Check pending MRs
+	if ref.PendingMRs != nil {
+		if mr, ok := ref.PendingMRs[id]; ok {
+			return 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 {
+	ref, err := m.loadState()
+	if err != nil {
+		return err
+	}
+
+	// Find the MR
+	var mr *MergeRequest
+	if ref.PendingMRs != nil {
+		mr = ref.PendingMRs[id]
+	}
+	if mr == nil {
+		return ErrMRNotFound
+	}
+
+	// Verify it's in a failed state (open with an error)
+	if mr.Status != MROpen || mr.Error == "" {
+		return ErrMRNotFailed
+	}
+
+	// Clear the error to mark as ready for retry
+	mr.Error = ""
+
+	// Save the state
+	if err := m.saveState(ref); err != nil {
+		return err
+	}
+
+	// If --now flag, process immediately
+	if processNow {
+		result := m.ProcessMR(mr)
+		if !result.Success {
+			return fmt.Errorf("retry failed: %s", result.Error)
+		}
+	}
+
+	return nil
+}
+
+// RegisterMR adds a merge request to the pending queue.
+func (m *Manager) RegisterMR(mr *MergeRequest) error {
+	ref, err := m.loadState()
+	if err != nil {
+		return err
+	}
+
+	if ref.PendingMRs == nil {
+		ref.PendingMRs = make(map[string]*MergeRequest)
+	}
+
+	ref.PendingMRs[mr.ID] = mr
+	return m.saveState(ref)
+}
+
 // findTownRoot walks up directories to find the town root.
 func findTownRoot(startPath string) string {
 	path := startPath

internal/refinery/manager_test.go

@@ -0,0 +1,172 @@
+package refinery
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/steveyegge/gastown/internal/rig"
+)
+
+func setupTestManager(t *testing.T) (*Manager, string) {
+	t.Helper()
+
+	// Create temp directory structure
+	tmpDir := t.TempDir()
+	rigPath := filepath.Join(tmpDir, "testrig")
+	if err := os.MkdirAll(filepath.Join(rigPath, ".gastown"), 0755); err != nil {
+		t.Fatalf("mkdir .gastown: %v", err)
+	}
+
+	r := &rig.Rig{
+		Name: "testrig",
+		Path: rigPath,
+	}
+
+	return NewManager(r), rigPath
+}
+
+func TestManager_GetMR(t *testing.T) {
+	mgr, _ := setupTestManager(t)
+
+	// Create a test MR in the pending queue
+	mr := &MergeRequest{
+		ID:       "gt-mr-abc123",
+		Branch:   "polecat/Toast/gt-xyz",
+		Worker:   "Toast",
+		IssueID:  "gt-xyz",
+		Status:   MROpen,
+		Error:    "test failure",
+	}
+
+	if err := mgr.RegisterMR(mr); err != nil {
+		t.Fatalf("RegisterMR: %v", err)
+	}
+
+	t.Run("find existing MR", func(t *testing.T) {
+		found, err := mgr.GetMR("gt-mr-abc123")
+		if err != nil {
+			t.Errorf("GetMR() unexpected error: %v", err)
+		}
+		if found == nil {
+			t.Fatal("GetMR() returned nil")
+		}
+		if found.ID != mr.ID {
+			t.Errorf("GetMR() ID = %s, want %s", found.ID, mr.ID)
+		}
+	})
+
+	t.Run("MR not found", func(t *testing.T) {
+		_, err := mgr.GetMR("nonexistent-mr")
+		if err != ErrMRNotFound {
+			t.Errorf("GetMR() error = %v, want %v", err, ErrMRNotFound)
+		}
+	})
+}
+
+func TestManager_Retry(t *testing.T) {
+	t.Run("retry failed MR clears error", func(t *testing.T) {
+		mgr, _ := setupTestManager(t)
+
+		// Create a failed MR
+		mr := &MergeRequest{
+			ID:       "gt-mr-failed",
+			Branch:   "polecat/Toast/gt-xyz",
+			Worker:   "Toast",
+			Status:   MROpen,
+			Error:    "merge conflict",
+		}
+
+		if err := mgr.RegisterMR(mr); err != nil {
+			t.Fatalf("RegisterMR: %v", err)
+		}
+
+		// Retry without processing
+		err := mgr.Retry("gt-mr-failed", false)
+		if err != nil {
+			t.Errorf("Retry() unexpected error: %v", err)
+		}
+
+		// Verify error was cleared
+		found, _ := mgr.GetMR("gt-mr-failed")
+		if found.Error != "" {
+			t.Errorf("Retry() error not cleared, got %s", found.Error)
+		}
+	})
+
+	t.Run("retry non-failed MR fails", func(t *testing.T) {
+		mgr, _ := setupTestManager(t)
+
+		// Create a successful MR (no error)
+		mr := &MergeRequest{
+			ID:     "gt-mr-success",
+			Branch: "polecat/Toast/gt-abc",
+			Worker: "Toast",
+			Status: MROpen,
+			Error:  "", // No error
+		}
+
+		if err := mgr.RegisterMR(mr); err != nil {
+			t.Fatalf("RegisterMR: %v", err)
+		}
+
+		err := mgr.Retry("gt-mr-success", false)
+		if err != ErrMRNotFailed {
+			t.Errorf("Retry() error = %v, want %v", err, ErrMRNotFailed)
+		}
+	})
+
+	t.Run("retry nonexistent MR fails", func(t *testing.T) {
+		mgr, _ := setupTestManager(t)
+
+		err := mgr.Retry("nonexistent", false)
+		if err != ErrMRNotFound {
+			t.Errorf("Retry() error = %v, want %v", err, ErrMRNotFound)
+		}
+	})
+}
+
+func TestManager_RegisterMR(t *testing.T) {
+	mgr, rigPath := setupTestManager(t)
+
+	mr := &MergeRequest{
+		ID:           "gt-mr-new",
+		Branch:       "polecat/Cheedo/gt-123",
+		Worker:       "Cheedo",
+		IssueID:      "gt-123",
+		TargetBranch: "main",
+		CreatedAt:    time.Now(),
+		Status:       MROpen,
+	}
+
+	if err := mgr.RegisterMR(mr); err != nil {
+		t.Fatalf("RegisterMR: %v", err)
+	}
+
+	// Verify it was saved to disk
+	stateFile := filepath.Join(rigPath, ".gastown", "refinery.json")
+	data, err := os.ReadFile(stateFile)
+	if err != nil {
+		t.Fatalf("reading state file: %v", err)
+	}
+
+	var ref Refinery
+	if err := json.Unmarshal(data, &ref); err != nil {
+		t.Fatalf("unmarshal state: %v", err)
+	}
+
+	if ref.PendingMRs == nil {
+		t.Fatal("PendingMRs is nil")
+	}
+
+	saved, ok := ref.PendingMRs["gt-mr-new"]
+	if !ok {
+		t.Fatal("MR not found in PendingMRs")
+	}
+
+	if saved.Worker != "Cheedo" {
+		t.Errorf("saved MR worker = %s, want Cheedo", saved.Worker)
+	}
+}

internal/refinery/types.go

@@ -38,6 +38,10 @@ type Refinery struct {
 	// CurrentMR is the merge request currently being processed.
 	CurrentMR *MergeRequest `json:"current_mr,omitempty"`
 
+	// PendingMRs tracks merge requests that have been submitted.
+	// Key is the MR ID.
+	PendingMRs map[string]*MergeRequest `json:"pending_mrs,omitempty"`
+
 	// LastMergeAt is when the last successful merge happened.
 	LastMergeAt *time.Time `json:"last_merge_at,omitempty"`