feat(todo-cleanup): add --convert-subtasks dated-rewrite mode

Rewrites every level-3+ DONE/CANCELLED/FAILED heading into a dated event-log entry from its CLOSED cookie, enforcing the todo-format depth rule that interactive closes and --archive-done (level-2 only) leave unapplied. A new lint-org checker (subtask-done-not-dated) flags stragglers, and the clean-todo, wrap-up, open-tasks, and task-review workflows now run the converter before archiving.

Removing the CLOSED cookie keeps a DEADLINE or SCHEDULED cookie that shares its planning line, rather than dropping the whole line.

From the .emacs.d handoff (2026-07-01 convert-subtasks bundle).

1 files changed, 28 insertions, 0 deletions

diff --git a/.ai/scripts/lint-org.el b/.ai/scripts/lint-org.el
index 5447cb3..90b1b1d 100644
--- a/.ai/scripts/lint-org.el
+++ b/.ai/scripts/lint-org.el
@@ -35,6 +35,7 @@
 ;;   empty-heading                     bare stars with no title
 ;;   malformed-priority-cookie         [#x]-shaped token org rejected
 ;;   level2-done-without-closed        completed level-2 task with no CLOSED
+;;   subtask-done-not-dated            level-3+ done sub-task still a DONE keyword
 ;;   (anything else)                   surfaced as judgment with checker name
 ;;
 ;; Output format on stdout:
@@ -503,6 +504,32 @@ the live file on the next `task-sorted'."
                "level-2 DONE/CANCELLED has no CLOSED date — add CLOSED: [YYYY-MM-DD Day]; task-sorted's aging step archives an undated completed task immediately"))))))))
 
 ;;; ---------------------------------------------------------------------------
+;;; level-3+ dated-header check (claude-rules/todo-format.md)
+;;
+;; The inverse of the level-2 check above.  A completed sub-task — a heading at
+;; level 3 or deeper, under a parent task — becomes a dated event-log entry, not
+;; a DONE keyword, so the parent's subtree grows a chronological history instead
+;; of a long tail of nested DONE lines.  An interactive org close
+;; (`org-log-done' → DONE + CLOSED) leaves the keyword in place, and
+;; `--archive-done' only touches level 2, so these accumulate.  Flag them for
+;; conversion.  Judgment-only and regex-based (independent of which TODO keywords
+;; the batch Emacs recognizes); todo-cleanup.el --convert-subtasks does the fix.
+
+(defun lo--check-subtask-done-not-dated ()
+  "Flag level-3+ headings carrying a done keyword (DONE/CANCELLED/FAILED).
+Emits one judgment item per offending heading (checker
+`subtask-done-not-dated')."
+  (save-excursion
+    (goto-char (point-min))
+    ;; Case-sensitive: the keywords are uppercase, not the words in a title.
+    (let ((case-fold-search nil))
+      (while (re-search-forward
+              "^\\*\\{3,\\} \\(DONE\\|CANCELLED\\|FAILED\\) " nil t)
+        (lo--emit-judgment
+         'subtask-done-not-dated (line-number-at-pos)
+         "level-3+ done sub-task should be a dated event-log entry (todo-format.md): run todo-cleanup.el --convert-subtasks to rewrite it")))))
+
+;;; ---------------------------------------------------------------------------
 ;;; File processing
 
 (defun lo--backup (file)
@@ -543,6 +570,7 @@ left unmodified and mechanical entries are recorded with :preview t."
           (lo--check-empty-headings)
           (lo--check-malformed-priority-cookies)
           (lo--check-level2-done-without-closed)
+          (lo--check-subtask-done-not-dated)
           (when (and (not lo-check-only) (buffer-modified-p))
             (save-buffer)))
       (with-current-buffer buf (set-buffer-modified-p nil))