Support todolist name resolution and improve cross-project validation

- Resolve --list via resolveTodolistInTodoset so names like "Sprint 1"
  work, not just numeric IDs and URLs
- Use project context from todo URL, --in flag, and config for both
  name resolution and cross-project validation
- Use ErrUsageHint for the cross-project error to show actionable guidance
- Update help text and SKILL.md placeholder to reflect name support

Author: jeremy

internal/commands/todos.go

@@ -1627,6 +1627,7 @@ You can pass either a todo ID or a Basecamp URL:
   basecamp todos position https://3.basecamp.com/123/buckets/456/todos/789 --to 1
 
 Move to a different todolist in the same project:
+  basecamp todos position 789 --to 1 --list "Sprint 1" --in myproject
   basecamp todos position 789 --to 1 --list 321
   basecamp todos position <todo-url> --to 1 --list <todolist-url>`,
 		RunE: func(cmd *cobra.Command, args []string) error {
@@ -1660,10 +1661,37 @@ Move to a different todolist in the same project:
 			if list != "" {
 				listIDStr, listProjectID := extractWithProject(list)
 
+				// Build project context: todo URL > --in flag > config
+				project := todoProjectID
+				if project == "" {
+					project = app.Flags.Project
+				}
+				if project == "" {
+					project = app.Config.ProjectID
+				}
+
 				// Cross-project moves are not supported by the reposition endpoint
-				if todoProjectID != "" && listProjectID != "" && todoProjectID != listProjectID {
-					return output.ErrUsage("Cannot move a todo to a list in a different project. " +
-						"Cross-project moves are not yet supported.")
+				if project != "" && listProjectID != "" && project != listProjectID {
+					return output.ErrUsageHint(
+						"Cannot move a todo to a list in a different project.",
+						"Pass a todolist from the same project; cross-project moves are not supported.",
+					)
+				}
+
+				// Resolve todolist name to ID when not already numeric
+				if !isNumeric(listIDStr) {
+					if project == "" {
+						return output.ErrUsage("--in is required to resolve todolist names")
+					}
+					resolvedProject, _, resolveErr := app.Names.ResolveProject(cmd.Context(), project)
+					if resolveErr != nil {
+						return resolveErr
+					}
+					resolved, resolveErr := resolveTodolistInTodoset(cmd, app, listIDStr, resolvedProject, "")
+					if resolveErr != nil {
+						return resolveErr
+					}
+					listIDStr = resolved
 				}
 
 				listID, parseErr := strconv.ParseInt(listIDStr, 10, 64)
@@ -1698,7 +1726,7 @@ Move to a different todolist in the same project:
 
 	cmd.Flags().IntVar(&position, "to", 0, "Target position, 1-based (1 = top)")
 	cmd.Flags().IntVar(&position, "position", 0, "Target position (alias for --to)")
-	cmd.Flags().StringVarP(&list, "list", "l", "", "Destination todolist ID or URL (move to a different list)")
+	cmd.Flags().StringVarP(&list, "list", "l", "", "Destination todolist ID, name, or URL (move to a different list)")
 
 	return cmd
 }

skills/basecamp/SKILL.md

@@ -352,7 +352,7 @@ basecamp unassign <id> [id...] --card --from <person> --in <project> # Remove ca
 basecamp assign <id> [id...] --step --to <person> --in <project>   # Assign card step
 basecamp unassign <id> [id...] --step --from <person> --in <project> # Remove step assignee
 basecamp todos position <id> --to 1                     # Move to top
-basecamp todos position <id> --to 1 --list <list>       # Move to different list
+basecamp todos position <id> --to 1 --list <id|name|url> # Move to different list
 basecamp todos sweep --overdue --complete --comment "Done" --in <project>
 ```