fix: stop tooltip dedup from hiding distinct events sharing a title

`chime--deduplicate-events-by-title' was keying off the user-facing
title alone, so two real "1:1" entries on different days collapsed to
one and the second one disappeared from the tooltip.

I changed the key to `(marker-file . marker-pos)' — the source heading
identity — so distinct headings keep both copies and recurring expansions
of one heading still fold to the soonest. When marker info is missing
(synthesized test events, edge cases) the key falls back to title, which
preserves the older fixtures the function was originally tested against.

Three new tests cover the regression paths: two distinct headings sharing
a title both survive, one heading expanded into multiple instances still
collapses to the soonest, and a mix of sourced and unsourced events
behaves correctly under both code paths.

1 files changed, 23 insertions, 14 deletions

diff --git a/chime.el b/chime.el
index 2bc1b75..3dafc48 100644
--- a/chime.el
+++ b/chime.el
@@ -1079,27 +1079,36 @@ Left-click opens calendar URL (if set), right-click jumps to event."
                   'local-map map))))
 
 (defun chime--deduplicate-events-by-title (upcoming-events)
-  "Deduplicate UPCOMING-EVENTS by title, keeping soonest occurrence.
+  "Collapse UPCOMING-EVENTS that come from the same source heading.
 
 UPCOMING-EVENTS should be a list where each element is
-\(EVENT TIME-INFO MINUTES).
-Returns a new list with only the soonest occurrence of each
-unique title.
-
-This prevents recurring events from appearing multiple times in
-the tooltip when `org-agenda-list' expands them into separate
-event objects."
-  (let ((title-hash (make-hash-table :test 'equal)))
+\(EVENT TIME-INFO MINUTES).  Returns a new list with one entry per
+source heading, keeping the soonest occurrence.
+
+The dedup key is the heading's marker (`marker-file' + `marker-pos'
+on the event alist) so two distinct headings sharing a display title
+both survive — for example, two separate \"1:1\" entries on different
+days.  When marker info is missing (typically synthesized test events),
+the key falls back to the title so older callers and fixtures keep
+working.
+
+The function still earns its keep against `org-agenda-list', which
+expands a recurring entry into multiple instances all sharing one
+marker; those collapse to a single soonest tooltip line."
+  (let ((id-hash (make-hash-table :test 'equal)))
     (dolist (item upcoming-events)
       (let* ((event (car item))
-             (title (cdr (assoc 'title event)))
              (minutes (caddr item))
-             (existing (gethash title title-hash)))
-        ;; Only keep if this is the first occurrence or soonest so far
+             (marker-file (cdr (assoc 'marker-file event)))
+             (marker-pos (cdr (assoc 'marker-pos event)))
+             (key (if (and marker-file marker-pos)
+                      (cons marker-file marker-pos)
+                    (cdr (assoc 'title event))))
+             (existing (gethash key id-hash)))
         (when (or (not existing)
                   (< minutes (caddr existing)))
-          (puthash title item title-hash))))
-    (hash-table-values title-hash)))
+          (puthash key item id-hash))))
+    (hash-table-values id-hash)))
 
 (defun chime--find-soonest-time-in-window (times now lookahead-minutes)
   "Find soonest time from TIMES list within LOOKAHEAD-MINUTES from NOW.