Coalesce continuous annotation bars into one jump point

A continuous selection across N clips is N marks → N bars, and OTIO's fractional
media offsets leave ~1-frame gaps between adjacent clips, so the jump control
showed "jump (5)" for a continuous stretch. merge-bars snaps bar endpoints to
whole frames and joins touching ranges; only a real >=1-frame gap splits.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tl/src/tl/scene.cljs

@@ -54,6 +54,21 @@
                  (when (< lo hi) [(+ c (- lo a)) (+ c (- hi a))])))
              segs)))
 
+(defn merge-bars
+  "Coalesce [lo hi) ranges that meet at a frame boundary into single bars, so a
+   continuous selection spanning several clips reads as one piece. Endpoints snap
+   to whole frames first, which absorbs the sub-frame gaps OTIO's fractional
+   media offsets leave between adjacent clips; only a real (≥1 frame) gap splits."
+  [bars]
+  (reduce (fn [acc [lo hi]]
+            (let [lo (js/Math.floor lo) hi (js/Math.ceil hi)
+                  [plo phi] (peek acc)]
+              (if (and plo (<= lo phi))
+                (conj (pop acc) [plo (max phi hi)])
+                (conj acc [lo hi]))))
+          []
+          (sort-by first bars)))
+
 (defn slice
   "Sub-segments of `segs` covering local range [la lb), src + local re-cut."
   [segs la lb]

tl/src/tl/subs.cljs

@@ -72,7 +72,8 @@
           (keep (fn [[gid g]]
                   (when (and (= :annotation (:type g)) (= ctx (:parent g)))
                     (let [src-segs (scene/resolve scene gid)
-                          bars     (vec (mapcat (fn [{[a b] :src}] (scene/pieces segs a b)) src-segs))
+                          bars     (scene/merge-bars
+                                    (mapcat (fn [{[a b] :src}] (scene/pieces segs a b)) src-segs))
                           reason   (scene/broken-reason scene gid)]
                       {:id gid :name (:name g) :color (or (:color g) "#4e8fc2")
                        :content (:content g) :children (count (:marks g))

tl/test/tl/scene_test.cljs

@@ -221,6 +221,15 @@
         (is (= 0  (get-in (first marks) [:start :at])))
         (is (= 30 (get-in (first marks) [:end :at])))))))
 
+(deftest merge-bars-coalesces-continuous-run
+  (testing "sub-frame OTIO gaps collapse to one bar; a real gap stays split"
+    ;; foobar's real bars (continuous 5-clip selection, ~0.9-frame source gaps)
+    (is (= [[128 542]]
+           (s/merge-bars [[128.87 190.87] [191.80 265.80] [266.73 384.73]
+                          [385.61 413.61] [414.58 541.58]])))
+    (is (= [[0 50] [200 260]] (s/merge-bars [[0 50] [200 260]])))   ; real gap → two
+    (is (= [] (s/merge-bars [])))))
+
 (deftest restore-annotations-rekeywordizes-json
   (testing "a JSON-roundtripped annotation (string :type/:parent/:ref) is restored + resolves"
     (let [json-like {:ann-1 {:type "annotation" :parent "root" :name "x"