CB-118: clip the completion baseline so the CB-115 guard survives >cap blocks

captureBaseline stored the raw, unclipped last-assistant block while resolve()
compares against clip(...) capped at MAX_SCRAPE_CHARS. For a block longer than
4000 chars the two capped representations never match even when the pane is
unchanged, defeating the CB-115 misattribution guard and letting a stale
completion resolve a rapid back-to-back send. Clip the baseline identically.

Regression test: an unchanged >cap block stays suppressed.

Surfaced by the fan-out issue-hunt E2E (1 primary -> 3 concurrent workers,
e2e/issue_hunt_test.py, added here). The same hunt's WorkerService.stop() and
Rendezvous.complete() findings were verified as false positives (locatePane is
already guarded; the sender's finally-close already removes the waiter).

Closes #2

bridged/src/test/java/dev/ltms/bridged/inject/CompletionResolverTest.java

@@ -156,6 +156,31 @@ class CompletionResolverTest {
         assertEquals("No, 391 = 17 × 23.", waiter.getNow(null).text());
     }
 
+    @Test
+    void suppressesAnUnchangedCompletionEvenWhenTheBlockExceedsTheScrapeCap() {
+        // The fan-out issue-hunt finding: captureBaseline once stored the RAW (unclipped) assistant
+        // block while resolve compares against a clip()'d tail. For a block longer than MAX_SCRAPE_CHARS
+        // the two capped representations differ even when the pane never changed, so the CB-115
+        // byte-identical guard failed to fire and a stale completion could resolve the send. Both sides
+        // must clip identically; here an unchanged >cap block on rapid back-to-back turns stays suppressed.
+        String longBlock = "⏺ " + "x".repeat(CompletionResolver.MAX_SCRAPE_CHARS + 500) + "\n❯ ";
+        FakeHerdr herdr = new FakeHerdr().readText(longBlock);
+        Rendezvous rendezvous = new Rendezvous();
+        CompletionResolver resolver = new CompletionResolver(new AgentControl(herdr), rendezvous);
+
+        var waiter = rendezvous.open("term_a");        // a send is blocked on this turn
+        resolver.captureBaseline("term_a");            // baseline is the clipped >cap block
+        var turn = resolver.inFlight("term_a");
+        assertEquals(CompletionResolver.MAX_SCRAPE_CHARS, turn.baseline().length(),
+                "the delivery baseline is clipped to the same cap resolve() applies to the tail");
+
+        resolver.resolve("term_a", turn);              // scrape unchanged → clipped tail == baseline → suppress
+
+        assertFalse(waiter.isDone(),
+                "an unchanged >cap block must still be recognised as stale and suppressed");
+        assertTrue(rendezvous.isWaiting("term_a"), "the send stays waiting for a real reply");
+    }
+
     @Test
     void resolvesWhenThereIsNoBaseline() {
         // No delivery baseline (e.g. the pre-turn read failed) ⇒ never suppress; the completion resolves.