Add 'last touched' issue tracking for update/close without ID

When no issue ID is provided to `bd update` or `bd close`, use the last
touched issue from the most recent create, update, show, or close operation.

This addresses the common workflow where you create an issue and then
immediately want to add more details (like changing priority from P2 to P4)
without re-typing the issue ID.

Implementation:
- New file last_touched.go with Get/Set/Clear functions
- Store last touched ID in .beads/last-touched (gitignored)
- Track on create, update, show, and close operations
- Allow update/close with zero args to use last touched

(bd-s2t)

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

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

cmd/bd/update.go

@@ -18,9 +18,23 @@ var updateCmd = &cobra.Command{
 	Use:     "update [id...]",
 	GroupID: "issues",
 	Short:   "Update one or more issues",
-	Args:    cobra.MinimumNArgs(1),
+	Long: `Update one or more issues.
+
+If no issue ID is provided, updates the last touched issue (from most recent
+create, update, show, or close operation).`,
+	Args: cobra.MinimumNArgs(0),
 	Run: func(cmd *cobra.Command, args []string) {
 		CheckReadonly("update")
+
+		// If no IDs provided, use last touched issue
+		if len(args) == 0 {
+			lastTouched := GetLastTouchedID()
+			if lastTouched == "" {
+				FatalErrorRespectJSON("no issue ID provided and no last touched issue")
+			}
+			args = []string{lastTouched}
+		}
+
 		updates := make(map[string]interface{})
 
 		if cmd.Flags().Changed("status") {
@@ -141,6 +155,7 @@ var updateCmd = &cobra.Command{
 		// If daemon is running, use RPC
 		if daemonClient != nil {
 			updatedIssues := []*types.Issue{}
+			var firstUpdatedID string // Track first successful update for last-touched
 			for _, id := range resolvedIDs {
 				updateArgs := &rpc.UpdateArgs{ID: id}
 
@@ -213,16 +228,27 @@ var updateCmd = &cobra.Command{
 				if !jsonOutput {
 					fmt.Printf("%s Updated issue: %s\n", ui.RenderPass("✓"), id)
 				}
+
+				// Track first successful update for last-touched
+				if firstUpdatedID == "" {
+					firstUpdatedID = id
+				}
 			}
 
 			if jsonOutput && len(updatedIssues) > 0 {
 				outputJSON(updatedIssues)
 			}
+
+			// Set last touched after all updates complete
+			if firstUpdatedID != "" {
+				SetLastTouchedID(firstUpdatedID)
+			}
 			return
 		}
 
 		// Direct mode
 		updatedIssues := []*types.Issue{}
+		var firstUpdatedID string // Track first successful update for last-touched
 		for _, id := range resolvedIDs {
 			// Check if issue is a template: templates are read-only
 			issue, err := store.GetIssue(ctx, id)
@@ -324,6 +350,16 @@ var updateCmd = &cobra.Command{
 			} else {
 				fmt.Printf("%s Updated issue: %s\n", ui.RenderPass("✓"), id)
 			}
+
+			// Track first successful update for last-touched
+			if firstUpdatedID == "" {
+				firstUpdatedID = id
+			}
+		}
+
+		// Set last touched after all updates complete
+		if firstUpdatedID != "" {
+			SetLastTouchedID(firstUpdatedID)
 		}
 
 		// Schedule auto-flush if any issues were updated