docs: keep the org-element cache reproduction evidenceHEADmain

Twelve scripts plus a README covering the persist-write cache corruption:
the no-dirvish root cause, the buffer-list ordering dependency, a faithful
replay of the file-manager preview path, and the two fixes I tried and
reverted.

The README says which scripts are weak evidence and why, so the next reader
doesn't rebuild an argument on the one whose control varied three things at
once.

Also holds the upstream bug report and its reproduction, verified to run
standalone under emacs -Q.

1 files changed, 49 insertions, 0 deletions

diff --git a/working/org-element-cache-persist-bug/refute-fontify-rearms.el b/working/org-element-cache-persist-bug/refute-fontify-rearms.el
new file mode 100644
index 00000000..fd55194b
--- /dev/null
+++ b/working/org-element-cache-persist-bug/refute-fontify-rearms.el
@@ -0,0 +1,49 @@
+;; Does the preview buffer re-register after the let unwinds, on fontification?
+(require 'org) (require 'org-element) (require 'org-persist)
+(defvar rk-dir (make-temp-file "refute-" t))
+(setq org-persist-directory (expand-file-name "persist" rk-dir))
+(setq org-element-use-cache t org-element-cache-persistent t org-log-done nil)
+(defvar rk-file (expand-file-name "notes.org" rk-dir))
+(with-temp-file rk-file
+  (dotimes (i 20) (insert (format "* TODO task %d\nbody with src_python{1+1} inline\n" i))))
+
+(defun rk-bufs (buf)
+  (with-current-buffer buf
+    (let (s) (avl-tree-mapc (lambda (el) (push (org-element-property :buffer el) s))
+                            org-element--cache)
+         (delete-dups s))))
+
+(let ((real (find-file-noselect rk-file)))
+  (with-current-buffer real
+    (org-element-cache-reset)
+    (org-element-cache-map #'ignore :granularity 'headline)
+    (goto-char (point-min)) (re-search-forward "^\\* TODO task 0") (beginning-of-line)
+    (org-todo "DONE"))
+  (message "before: %S" (rk-bufs real))
+  ;; preview WITH the fix's environment, then let it LIVE and fontify (the step my tests skip)
+  (let ((prev (get-buffer-create "*prev*")))
+    (with-current-buffer prev
+      (with-silent-modifications
+        (insert-file-contents rk-file nil 0 1048576)
+        (setq buffer-file-name rk-file))
+      (eval `(let ((inhibit-message t) (non-essential t)
+                   (enable-dir-local-variables nil) (enable-local-variables :safe)
+                   (org-element-use-cache nil))
+               (setq-local delay-mode-hooks t) (set-auto-mode) (font-lock-mode 1)))
+      (message "after set-auto-mode: local-cache=%S global=%S persist-hook=%S"
+               org-element-use-cache (default-value 'org-element-use-cache)
+               (and (memq 'org-persist-write-all-buffer kill-buffer-hook) t))
+      ;; THE MISSING STEP: the preview lives in a window and gets fontified
+      (font-lock-ensure)
+      (message "after fontify:      persist-hook=%S cache-active=%S"
+               (and (memq 'org-persist-write-all-buffer kill-buffer-hook) t)
+               (org-element--cache-active-p)))
+    (let (kill-buffer-query-functions) (kill-buffer prev)))
+  (message "after kill: %S" (rk-bufs real))
+  (with-current-buffer real
+    (message "parse => %s"
+             (condition-case e (progn (org-element-cache-map
+                                       (lambda (el) (org-element-property :raw-value el))
+                                       :granularity 'headline) "OK")
+               (error (format "ERROR %S" e))))))
+(delete-directory rk-dir t)