fix(calendar-sync): stop EXDATE scan loop on comma-separated values

calendar-sync--get-exdates read (match-end 0) after split-string, whose internal matching clobbers the match data. The scan position jumped back to a comma offset inside the value and re-matched the same EXDATE line forever, growing the result list until the kernel OOM killer took the whole session down (twice, 2026-07-13). The fix captures the line's end position before the split. The comma-separated tests added with a9e61207 were the first code to hit this path. All 12 exdates tests and all 56 calendar-sync test files now pass in milliseconds.

1 files changed, 9 insertions, 3 deletions

diff --git a/modules/calendar-sync-recurrence.el b/modules/calendar-sync-recurrence.el
index bc1cc92f..2689cdd6 100644
--- a/modules/calendar-sync-recurrence.el
+++ b/modules/calendar-sync-recurrence.el
@@ -195,10 +195,16 @@ Handles both simple values and values with parameters like TZID."
           (pos 0))
       ;; Find all EXDATE lines.  One line may carry several comma-separated
       ;; datetimes (RFC 5545); split them so each is excluded individually.
+      ;; Capture the match end BEFORE split-string: its internal matching
+      ;; clobbers the match data, and reading (match-end 0) afterwards made
+      ;; pos jump backwards to a comma offset inside the value -- re-matching
+      ;; the same line forever and growing the list until the OOM killer
+      ;; intervened (took two agent sessions down on 2026-07-13).
       (while (string-match "^EXDATE[^:\n]*:\\([^\n]+\\)" event-str pos)
-        (dolist (val (split-string (match-string 1 event-str) "," t))
-          (push val exdates))
-        (setq pos (match-end 0)))
+        (let ((line-end (match-end 0)))
+          (dolist (val (split-string (match-string 1 event-str) "," t))
+            (push val exdates))
+          (setq pos line-end)))
       (nreverse exdates))))
 
 (defun calendar-sync--get-exdate-line (event-str exdate-value)