diff --git a/fleetd/src/main/java/dev/ltms/fleet/inject/CompletionResolver.java b/fleetd/src/main/java/dev/ltms/fleet/inject/CompletionResolver.java
index 50755fc..7ad8406 100644
--- a/fleetd/src/main/java/dev/ltms/fleet/inject/CompletionResolver.java
+++ b/fleetd/src/main/java/dev/ltms/fleet/inject/CompletionResolver.java
@@ -548,8 +548,19 @@ public final class CompletionResolver implements TurnListener {
      * fast completion. Runs the same backend-error classification the normal and raw-scrape paths
      * apply, against whatever is on screen right now: a match together with the too-fast crash
      * signature notifies {@link #backendErrorSink} (only on the resolution that wins the race). A
-     * non-match stays the original generic too-fast failure, naming the member and both timings,
-     * with whatever the pane shows appended so the caller sees the cause, not just "it failed".
+     * non-match stays the generic too-fast failure, naming the member and both timings, with
+     * whatever the pane shows appended so the caller sees the evidence, not just "it failed".
+     *
+     * <p>fleetd#376: <strong>this path must never resolve a completion.</strong> A fast backend can
+     * genuinely answer inside the floor, so the failure is sometimes wrong — but it is wrong in the
+     * loud direction, and the fix for that is honest wording, not a guess at the pane's meaning.
+     * Reclassifying from the scrape was tried and rejected: there is no reliable positive marker for
+     * "this is a real reply" across backends. {@link #lastAssistantBlock} falls back to the entire
+     * pane when it finds no {@code ⏺} marker, so on a crash the candidate "reply" is the whole
+     * screen; and {@code ⏺} itself is a Claude Code marker that an opencode pane never carries — the
+     * very backend whose speed raised this ticket. Any weaker test (non-blank, or "contains sentence
+     * punctuation") passes on almost every crash, because a pane holding a file path, a version
+     * number or a hostname contains a full stop. That trades a loud wrong answer for a silent one.
      */
     private void failTooFast(String target, InFlight turn, CompletableFuture<Rendezvous.Resolution> waiter,
                               long elapsedNanos) {
@@ -560,13 +571,13 @@ public final class CompletionResolver implements TurnListener {
             scrape = "";
         }
         String clippedScrape = clip(scrape);
-        String baseReason = String.format(
-                "member %s went BUSY -> DONE in %dms (floor %dms) — too fast to be real work, most "
-                        + "likely a backend error before any work started",
+        String timing = String.format(
+                "member %s went BUSY -> DONE in %dms (floor %dms)",
                 target, elapsedNanos / 1_000_000, MIN_TURN_NANOS / 1_000_000);
         String backendError = firstMatchingLine(scrape, backendErrorPatternOrFallback(target));
         if (backendError != null) {
-            String reason = baseReason + ": " + clippedScrape;
+            String reason = timing + " — too fast to be real work, and the pane carries a backend "
+                    + "error: " + clippedScrape;
             if (rendezvous.resolveFailure(waiter, reason)) {
                 inFlight.remove(target, turn);
                 log.warn("failing send to {} via turn-stall fallback: {}", target, reason);
@@ -575,7 +586,14 @@ public final class CompletionResolver implements TurnListener {
             }
             return;
         }
-        fail(target, turn, clippedScrape.isBlank() ? baseReason : baseReason + ": " + clippedScrape);
+        // fleetd#376: no pattern matched, so the cause is genuinely unknown. Say that, rather than
+        // asserting a backend error the way this message used to — a fast backend really can finish
+        // inside the floor, and a reader who trusts a wrong cause stops looking at the pane.
+        String reason = timing + " — inside the floor. That is usually a backend error before any "
+                + "work started, but a fast backend can answer inside it too, and nothing here can "
+                + "tell those apart, so the turn is reported failed rather than guessed. Read the "
+                + "pane below before deciding which it was";
+        fail(target, turn, clippedScrape.isBlank() ? reason : reason + ": " + clippedScrape);
     }
 
     /**
diff --git a/fleetd/src/test/java/dev/ltms/fleet/inject/CompletionResolverTest.java b/fleetd/src/test/java/dev/ltms/fleet/inject/CompletionResolverTest.java
index e1aaab2..1d17799 100644
--- a/fleetd/src/test/java/dev/ltms/fleet/inject/CompletionResolverTest.java
+++ b/fleetd/src/test/java/dev/ltms/fleet/inject/CompletionResolverTest.java
@@ -357,6 +357,54 @@ class CompletionResolverTest {
                 "the failure carries whatever was on screen: " + waiter.getNow(null).text());
     }
 
+    @Test
+    void aPlausibleLookingReplyInsideTheFloorStillFails() {
+        // fleetd#376 guard. A fix was attempted that inspected the pane inside the floor and resolved
+        // a COMPLETION when the text "looked like a real reply". Every cheap test for that is unsafe:
+        // lastAssistantBlock falls back to the WHOLE pane when there is no ⏺ marker, and a crash pane
+        // almost always contains sentence punctuation — in a file path, a version, or a hostname.
+        // This pane is the trap: it reads like a finished answer and it is a backend failure.
+        FakeHerdr herdr = new FakeHerdr().readText(
+                "Error: connection reset while loading src/main/java/Foo.java v1.2.3\n❯ ");
+        Rendezvous rendezvous = new Rendezvous();
+        long[] clock = {10_000_000_000L};
+        CompletionResolver resolver = new CompletionResolver(new AgentControl(herdr), rendezvous,
+                ExhaustedPatternLookup.none(), ExhaustionSink.none(), () -> clock[0]);
+
+        var waiter = rendezvous.open("term_a");
+        var turn = new CompletionResolver.InFlight(waiter, null, clock[0]);
+        clock[0] += CompletionResolver.MIN_TURN_NANOS - 1; // inside the floor
+
+        resolver.resolve("term_a", turn);
+
+        assertEquals(Rendezvous.Kind.FAILED, waiter.getNow(null).kind(),
+                "inside the floor the verdict is always FAILED — never guess a completion from pane text");
+    }
+
+    @Test
+    void theTooFastFailureDoesNotAssertACauseItCannotKnow() {
+        // fleetd#376: the message used to say "most likely a backend error before any work started".
+        // When no error pattern matches, that cause is a guess, and a reader who believes it stops
+        // looking at the pane. The verdict stays FAILED; only the claim about WHY is withdrawn.
+        FakeHerdr herdr = new FakeHerdr().readText("I am running on opencode/mimo-v2.5-free.\n❯ ");
+        Rendezvous rendezvous = new Rendezvous();
+        long[] clock = {10_000_000_000L};
+        CompletionResolver resolver = new CompletionResolver(new AgentControl(herdr), rendezvous,
+                ExhaustedPatternLookup.none(), ExhaustionSink.none(), () -> clock[0]);
+
+        var waiter = rendezvous.open("term_a");
+        var turn = new CompletionResolver.InFlight(waiter, null, clock[0]);
+        clock[0] += CompletionResolver.MIN_TURN_NANOS - 1; // inside the floor
+
+        resolver.resolve("term_a", turn);
+
+        String text = waiter.getNow(null).text();
+        assertEquals(Rendezvous.Kind.FAILED, waiter.getNow(null).kind(), "still fails, still loud");
+        assertFalse(text.contains("most likely a backend error"),
+                "an unmatched fast turn must not assert a backend error: " + text);
+        assertTrue(text.contains("mimo-v2.5-free"), "the pane is still carried: " + text);
+    }
+
     @Test
     void aBusyToDoneTransitionJustOutsideTheFloorResolvesNormally() {
         FakeHerdr herdr = new FakeHerdr().readText("⏺ a real, if quick, answer\n❯ ");
@@ -1117,8 +1165,16 @@ class CompletionResolverTest {
         assertTrue(waiter.isDone());
         assertEquals(Rendezvous.Kind.FAILED, waiter.getNow(null).kind(),
                 "still a failure — the floor itself, not the pattern, is why");
-        assertTrue(waiter.getNow(null).text().contains("too fast to be real work"),
-                "a non-match inside the floor stays the generic too-fast reason: " + waiter.getNow(null).text());
+        // fleetd#376: this used to assert the phrase "too fast to be real work", which carried the
+        // claim "most likely a backend error before any work started". With no pattern matched that
+        // cause is a guess, so the wording was withdrawn. What this test really guards is unchanged:
+        // the floor alone still fails the turn, it stays generic, and it never notifies the sink.
+        String reason = waiter.getNow(null).text();
+        assertTrue(reason.contains("inside the floor"),
+                "a non-match inside the floor stays the generic floor reason: " + reason);
+        assertFalse(reason.contains("most likely a backend error"),
+                "a non-match must not assert a cause it did not establish: " + reason);
+        assertTrue(reason.contains("still starting up"), "the pane is still carried: " + reason);
         assertTrue(notified.isEmpty(), "a non-match must never notify the typed sink");
     }
 }