fix(save): detect comment edits with a rendered-Org hash, not the md round-trip

A comment whose markdown doesn't survive md->org->md (a heading, single-asterisk italics) was flagged changed on every save, because the dirty scan compared org-to-md of the rendered body against the stored markdown hash. When the comment was authored by someone else, that surfaced as "1 read-only comment skipped" on every save even though nothing had been edited.

Descriptions already dodge this: 9424b84 gave them LINEAR-DESC-ORG-SHA256 and compared Org-to-Org. I did the same for comments. pearl--format-comment now writes LINEAR-COMMENT-ORG-SHA256 (the rendered body hash), and a new pearl--comment-dirty-p compares the current body against it, falling back to the old markdown hash for comments rendered before the baseline existed. Both detection sites use it: the save scan and the edit-current-comment no-op check. The markdown hash stays for the remote-conflict gate.

2 files changed, 87 insertions, 27 deletions

diff --git a/pearl.el b/pearl.el
index 18c65c2..3ade6dc 100644
--- a/pearl.el
+++ b/pearl.el
@@ -1762,6 +1762,7 @@ A null author renders as `(unknown)'."
             (format ":LINEAR-COMMENT-ID:        %s\n" (or (plist-get comment :id) ""))
             (format ":LINEAR-COMMENT-AUTHOR-ID: %s\n" (or (plist-get comment :author-id) ""))
             (format ":LINEAR-COMMENT-SHA256:    %s\n" (secure-hash 'sha256 raw-body))
+            (format ":LINEAR-COMMENT-ORG-SHA256: %s\n" (secure-hash 'sha256 (string-trim body)))
             ":END:\n"
             (if (string-empty-p body) "" (concat body "\n")))))
 
@@ -3283,28 +3284,37 @@ track correctly across the in-place inserts and deletes the merge performs."
 
 ;;; Dirty detection (the save model's local scanners)
 
+(defun pearl--comment-dirty-p ()
+  "Return non-nil when the comment body at point differs from its last fetch.
+An Org-to-Org comparison against `LINEAR-COMMENT-ORG-SHA256' (the rendered body
+as fetched), so a comment whose markdown does not survive md->org->md (a heading
+or single-asterisk emphasis) is not mistaken for a local edit -- the same fix
+`pearl--subtree-dirty-p' applies to descriptions.  Comments rendered before that
+baseline existed fall back to the older markdown-round-trip comparison against
+`LINEAR-COMMENT-SHA256'; they migrate on the next re-render."
+  (let ((org-hash (org-entry-get nil "LINEAR-COMMENT-ORG-SHA256")))
+    (if org-hash
+        (not (string= (secure-hash 'sha256 (pearl--entry-body-at-point)) org-hash))
+      (let ((stored (or (org-entry-get nil "LINEAR-COMMENT-SHA256") "")))
+        (not (string= (secure-hash 'sha256 (pearl--org-to-md (pearl--entry-body-at-point)))
+                      stored))))))
+
 (defun pearl--changed-comment-candidates ()
   "Return comments under the issue at point whose body changed since fetch.
-Each is a plist (:comment-id :author-id :marker).  Local only: compares
-`secure-hash' of `pearl--org-to-md' of each comment body to its stored
-`LINEAR-COMMENT-SHA256' (taken over the markdown Linear stored, so the
-comparison must round-trip through markdown, as `pearl-edit-current-comment'
-does).  A candidate only means the body differs; ownership is decided later."
+Each is a plist (:comment-id :author-id :marker).  Local only, via
+`pearl--comment-dirty-p'.  A candidate only means the body differs; ownership is
+decided later."
   (let (candidates)
     (save-excursion
       (pearl--goto-heading-or-error)
       (let ((issue-end (save-excursion (org-end-of-subtree t t) (point))))
         (while (and (outline-next-heading) (< (point) issue-end))
           (let ((cid (org-entry-get nil "LINEAR-COMMENT-ID")))
-            (when (and cid (not (string-empty-p cid)))
-              (let ((stored (or (org-entry-get nil "LINEAR-COMMENT-SHA256") ""))
-                    (local (secure-hash 'sha256
-                                        (pearl--org-to-md (pearl--entry-body-at-point)))))
-                (unless (string= local stored)
-                  (push (list :comment-id cid
-                              :author-id (org-entry-get nil "LINEAR-COMMENT-AUTHOR-ID")
-                              :marker (point-marker))
-                        candidates))))))))
+            (when (and cid (not (string-empty-p cid)) (pearl--comment-dirty-p))
+              (push (list :comment-id cid
+                          :author-id (org-entry-get nil "LINEAR-COMMENT-AUTHOR-ID")
+                          :marker (point-marker))
+                    candidates))))))
     (nreverse candidates)))
 
 (defun pearl--priority-number-at-point ()
@@ -4728,23 +4738,21 @@ reported (refresh to reconcile)."
   (save-excursion
     (pearl--goto-heading-or-error "Not on a Linear comment")
     (let ((comment-id (org-entry-get nil "LINEAR-COMMENT-ID"))
-          (stored (org-entry-get nil "LINEAR-COMMENT-SHA256"))
           (marker (point-marker))
           (buf (current-buffer)))
       (unless comment-id
         (user-error "Not on a Linear comment"))
-      ;; No-op fast path before resolving the viewer: an unchanged comment
-      ;; costs no viewer lookup.  `pearl--entry-body-at-point' reads the text
-      ;; after the drawer and before the first child heading -- a comment
-      ;; subtree has that shape, so it serves the comment body unchanged.
-      (let ((local-md (pearl--org-to-md (pearl--entry-body-at-point))))
-        (if (string= (secure-hash 'sha256 local-md) (or stored ""))
-            (message "No comment changes to sync")
-          (pearl--viewer-async
-           (lambda (viewer)
-             (pearl--save-comment-field
-              marker (and viewer (plist-get viewer :id))
-              (lambda (outcome) (pearl--report-save-outcome outcome buf))))))))))
+      ;; No-op fast path before resolving the viewer: an unchanged comment costs
+      ;; no viewer lookup.  The dirty check is Org-to-Org (see
+      ;; `pearl--comment-dirty-p'), so a comment whose markdown does not survive
+      ;; the round-trip is not falsely seen as edited.
+      (if (not (pearl--comment-dirty-p))
+          (message "No comment changes to sync")
+        (pearl--viewer-async
+         (lambda (viewer)
+           (pearl--save-comment-field
+            marker (and viewer (plist-get viewer :id))
+            (lambda (outcome) (pearl--report-save-outcome outcome buf)))))))))
 
 ;;;###autoload
 (defun pearl-delete-current-comment ()
diff --git a/tests/test-pearl-comment-editing.el b/tests/test-pearl-comment-editing.el
index 32b194d..4853548 100644
--- a/tests/test-pearl-comment-editing.el
+++ b/tests/test-pearl-comment-editing.el
@@ -365,5 +365,57 @@ adds the comment there rather than refusing."
     (re-search-forward "see :note:")
     (should (string= "see :note: below\nand more text" (pearl--entry-body-at-point)))))
 
+;;; round-trip stability of the dirty check (the read-only-every-save fix)
+
+(defun test-pearl-comment-editing--commented-issue (body)
+  "An issue subtree whose one comment (by another user) has BODY."
+  (concat "** TODO ENG-1: x\n:PROPERTIES:\n:LINEAR-ID: i\n:END:\nissue body\n"
+          (pearl--format-comment
+           (list :id "c1" :author "Eric" :author-id "u-eric"
+                 :created-at "2026-01-01T00:00:00.000Z" :body body))))
+
+(ert-deftest test-pearl-comment-dirty-p-stable-for-lossy-markdown ()
+  "A freshly rendered comment whose markdown does not survive md->org->md
+(a heading, single-asterisk italics) is not seen as dirty."
+  (test-pearl--in-org (test-pearl-comment-editing--commented-issue
+                       "# Heading\n\nsome *italic* words")
+    (re-search-forward "LINEAR-COMMENT-ID")
+    (org-back-to-heading t)
+    (should-not (pearl--comment-dirty-p))))
+
+(ert-deftest test-pearl-comment-dirty-p-detects-a-real-edit ()
+  "An actual edit to the comment body is detected as dirty."
+  (test-pearl--in-org (test-pearl-comment-editing--commented-issue "original text")
+    (re-search-forward "LINEAR-COMMENT-ID")
+    (org-back-to-heading t)
+    (should-not (pearl--comment-dirty-p))
+    (goto-char (point-max))
+    (insert " EDITED")
+    (org-back-to-heading t)
+    (should (pearl--comment-dirty-p))))
+
+(ert-deftest test-pearl-changed-comment-candidates-ignores-unedited-lossy-comment ()
+  "The save scan does not flag an unedited comment with lossy markdown, so a
+non-viewer comment is no longer reported read-only on every save."
+  (test-pearl--in-org (test-pearl-comment-editing--commented-issue
+                       "## A heading\n\n*emphasis* and text")
+    (re-search-forward "^\\*\\* ")
+    (org-back-to-heading t)
+    (should-not (pearl--changed-comment-candidates))))
+
+(ert-deftest test-pearl-comment-dirty-p-legacy-falls-back-to-md-hash ()
+  "A comment rendered before the Org baseline existed (no LINEAR-COMMENT-ORG-SHA256)
+falls back to the markdown-hash comparison, so a clean legacy comment is not dirty."
+  (test-pearl--in-org
+      (concat "** TODO ENG-1: x\n:PROPERTIES:\n:LINEAR-ID: i\n:END:\n"
+              "**** Eric — 2026-01-01T00:00:00.000Z\n:PROPERTIES:\n"
+              ":LINEAR-COMMENT-ID:        c1\n"
+              ":LINEAR-COMMENT-AUTHOR-ID: u-eric\n"
+              (format ":LINEAR-COMMENT-SHA256:    %s\n" (secure-hash 'sha256 "plain body"))
+              ":END:\nplain body\n")
+    (re-search-forward "LINEAR-COMMENT-ID")
+    (org-back-to-heading t)
+    (should-not (pearl--comment-dirty-p))))
+
 (provide 'test-pearl-comment-editing)
 ;;; test-pearl-comment-editing.el ends here