fix: prevent closing issues with open blockers (GH#962)

Added IsBlocked method to Storage interface that checks if an issue is
in the blocked_issues_cache and returns the blocking issue IDs.

The close command now checks for blockers before allowing an issue to
be closed:
- If an issue has open blockers, closing is blocked with an error message
- The --force flag overrides this check
- Works in both daemon mode (RPC) and direct storage mode
- Also handles cross-rig routed IDs

This addresses the bug where agents could close a bead even when it
depends on an open bug/issue.

Closes #962

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

internal/rpc/protocol.go

@@ -174,6 +174,7 @@ type CloseArgs struct {
 	Reason      string `json:"reason,omitempty"`
 	Session     string `json:"session,omitempty"`      // Claude Code session ID that closed this issue
 	SuggestNext bool   `json:"suggest_next,omitempty"` // Return newly unblocked issues (GH#679)
+	Force       bool   `json:"force,omitempty"`        // Force close even with open blockers (GH#962)
 }
 
 // CloseResult is returned when SuggestNext is true (GH#679)

internal/rpc/server_issues_epics.go

@@ -831,6 +831,23 @@ func (s *Server) handleClose(req *Request) Response {
 		}
 	}
 
+	// Check if issue has open blockers (GH#962)
+	if !closeArgs.Force {
+		blocked, blockers, err := store.IsBlocked(ctx, closeArgs.ID)
+		if err != nil {
+			return Response{
+				Success: false,
+				Error:   fmt.Sprintf("failed to check blockers: %v", err),
+			}
+		}
+		if blocked && len(blockers) > 0 {
+			return Response{
+				Success: false,
+				Error:   fmt.Sprintf("cannot close %s: blocked by open issues %v (use --force to override)", closeArgs.ID, blockers),
+			}
+		}
+	}
+
 	// Capture old status for rich mutation event
 	oldStatus := ""
 	if issue != nil {