Make prompt capture fast and resilient

Hop-State: A_06FN8D0CK06GY5XBDYZ632R
Hop-Proposal: R_06FN8CY2FJBV5QA0WFEDWHR
Hop-Task: T_06FN8C4PMFJRT8APV4G03Y8
Hop-Attempt: AT_06FN8C4PMFRJEE4B7KKQ740

internal/hop/git.go

@@ -655,6 +655,27 @@ func (r *Repository) ReadHiddenRef(ctx context.Context, name string) (oid string
 	return r.ReadRef(ctx, ref)
 }
 
+// ListHiddenRefs reads all refs below refs/hop in one Git process. Keys are
+// relative to refs/hop/ (for example, "states/P_..." or "accepted").
+func (r *Repository) ListHiddenRefs(ctx context.Context) (map[string]string, error) {
+	output, err := r.run(ctx, nil, nil, "for-each-ref", "--format=%(refname) %(objectname)", hiddenRefPrefix)
+	if err != nil {
+		return nil, err
+	}
+	refs := make(map[string]string)
+	for _, line := range strings.Split(strings.TrimSpace(output), "\n") {
+		if line == "" {
+			continue
+		}
+		name, oid, found := strings.Cut(line, " ")
+		if !found || !strings.HasPrefix(name, hiddenRefPrefix) {
+			return nil, fmt.Errorf("unexpected hidden ref listing %q", line)
+		}
+		refs[strings.TrimPrefix(name, hiddenRefPrefix)] = strings.TrimSpace(oid)
+	}
+	return refs, nil
+}
+
 // UpdateHiddenRef atomically updates refs/hop/name. With no expectedOld value,
 // it is unconditional. Passing expectedOld performs compare-and-swap; an empty
 // expected value means the ref must not exist.

internal/hop/service.go

@@ -1640,17 +1640,17 @@ func (s *Service) reconcileDerivedRefs(ctx context.Context, reconcileAccepted bo
 	if err != nil {
 		return err
 	}
+	refs, err := s.Repo.ListHiddenRefs(ctx)
+	if err != nil {
+		return err
+	}
 	for _, row := range rows {
 		state := row.State
-		if err := s.Repo.VerifyObjects(ctx, state.GitCommit, state.SourceTree); err != nil {
-			return fmt.Errorf("state %s references unavailable Git data: %w", state.ID, err)
-		}
 		name := "states/" + state.ID
-		commit, exists, err := s.Repo.ReadHiddenRef(ctx, name)
-		if err != nil {
-			return err
-		}
-		if !exists || commit != state.GitCommit {
+		if refs[name] != state.GitCommit {
+			if err := s.Repo.VerifyObjects(ctx, state.GitCommit, state.SourceTree); err != nil {
+				return fmt.Errorf("state %s references unavailable Git data: %w", state.ID, err)
+			}
 			if err := s.Repo.UpdateHiddenRef(ctx, name, state.GitCommit); err != nil {
 				return fmt.Errorf("repair Git pin for state %s: %w", state.ID, err)
 			}
@@ -1668,11 +1668,7 @@ func (s *Service) reconcileDerivedRefs(ctx context.Context, reconcileAccepted bo
 	if err != nil {
 		return err
 	}
-	commit, exists, err := s.Repo.ReadHiddenRef(ctx, acceptedRef)
-	if err != nil {
-		return err
-	}
-	if !exists || commit != head.GitCommit {
+	if refs[acceptedRef] != head.GitCommit {
 		if err := s.Repo.UpdateHiddenRef(ctx, acceptedRef, head.GitCommit); err != nil {
 			return fmt.Errorf("repair accepted Git ref: %w", err)
 		}