fleetd#201 Unit 1: typed backend-error classification in CompletionResolver

Replace the hardcoded API-Error check with a target-keyed BackendErrorPatternLookup
plus a BackendErrorSink, mirroring the existing ExhaustedPatternLookup/ExhaustionSink
pair. Classifies in all three paths (normal block, #211 raw-scrape fallback, and the
fleetd#164 MIN_TURN_NANOS floor). The sink fires only after Rendezvous.resolveFailure
wins for the exact waiter. A target with no configured pattern still falls back to the
narrow (?i)\bAPI Error\s*: compatibility pattern. Existing constructors keep compiling
via BackendErrorPatternLookup.legacy() / BackendErrorSink.none() defaults.

Public send result is unchanged (still a failed send) — the typed sink event is the
internal seam Unit 5 will consume.

fleetd/src/main/java/dev/ltms/fleet/inject/BackendErrorPatternLookup.java

@@ -0,0 +1,35 @@
+package dev.ltms.fleet.inject;
+
+import java.util.regex.Pattern;
+
+/**
+ * Per-target lookup for a profile's configured backend-error pattern (fleetd#201 / #227): how
+ * {@link CompletionResolver} recognizes a backend that failed a turn outright (a credential
+ * outage, a provider 5xx) from whatever ends up on the member's pane, apart from a genuine
+ * completion.
+ *
+ * <p>The pattern is always profile config, never a vendor string in Java source: every backend
+ * words its failure differently, so a hardcoded sentence would only ever match one of them. A
+ * target with no configured pattern is not "off" the way {@link ExhaustedPatternLookup#none()}
+ * is — {@link CompletionResolver} falls back to its narrow {@code (?i)\bAPI Error\s*:}
+ * compatibility pattern instead, so classification still happens, just without a profile-specific
+ * match. {@link #legacy()} is the explicit stand-in existing (pre-fleetd#201) callers pass to get
+ * exactly that fallback-only behavior until a caller wires a real, profile-driven lookup
+ * (fleetd#201 Unit 5).
+ */
+@FunctionalInterface
+public interface BackendErrorPatternLookup {
+
+    /** The compiled pattern configured for {@code target}'s profile, or {@code null} if none. */
+    Pattern patternFor(String target);
+
+    /**
+     * Legacy lookup — no profile has a configured pattern, so {@link CompletionResolver} classifies
+     * every target using only its built-in {@code (?i)\bAPI Error\s*:} compatibility pattern. The
+     * explicit stand-in existing constructors pass so their behavior is unchanged until a caller
+     * wires a real, profile-driven lookup.
+     */
+    static BackendErrorPatternLookup legacy() {
+        return target -> null;
+    }
+}

fleetd/src/main/java/dev/ltms/fleet/inject/BackendErrorSink.java

@@ -0,0 +1,35 @@
+package dev.ltms.fleet.inject;
+
+/**
+ * Notified when {@link CompletionResolver} actually delivers a typed backend-error classification
+ * to a waiting send (fleetd#201 / #227) — never on a race that lost. {@link CompletionResolver}
+ * calls this only after {@code Rendezvous.resolveFailure} returns {@code true} for that exact
+ * waiter, mirroring the win-only race rule {@link ExhaustionSink} already uses.
+ *
+ * <p>The public send result is unchanged by this classification — it is still a failed send
+ * ({@code Rendezvous.Kind#FAILED}); this sink is the internal seam a later stage (fleetd#201 Unit
+ * 5, the policy that cools a credential off after two such failures in 60 seconds and tells the
+ * lead) consumes. {@link CompletionResolver} knows only {@code target} (a herdr terminal id); it
+ * has no notion of profiles or credentials, so mapping {@code target} to whatever should be
+ * quarantined is entirely the sink's job — exactly like {@link ExhaustionSink}.
+ */
+@FunctionalInterface
+public interface BackendErrorSink {
+
+    /**
+     * @param target      the herdr terminal id whose turn was classified as a backend error
+     * @param matchedLine the single pane line that matched the backend-error pattern
+     * @param reason      the full failure reason carried by the classification (the matched line
+     *                    plus whatever pane context the classifying path attaches)
+     */
+    void onBackendError(String target, String matchedLine, String reason);
+
+    /**
+     * Inert sink — nothing happens on a backend-error classification. The explicit stand-in a
+     * caller (or a test not exercising this feature) passes instead of a defaulting overload,
+     * exactly like {@link ExhaustionSink#none()}.
+     */
+    static BackendErrorSink none() {
+        return (target, matchedLine, reason) -> { };
+    }
+}

fleetd/src/main/java/dev/ltms/fleet/inject/CompletionResolver.java

@@ -89,6 +89,8 @@ public final class CompletionResolver implements TurnListener {
     private final Rendezvous rendezvous;
     private final ExhaustedPatternLookup exhaustedPatterns;
     private final ExhaustionSink exhaustionSink;
+    private final BackendErrorPatternLookup backendErrorPatterns;
+    private final BackendErrorSink backendErrorSink;
     private final LongSupplier nowNanos;
 
     /**
@@ -129,10 +131,48 @@ public final class CompletionResolver implements TurnListener {
      *                          classification actually resolves a waiter. Required for the same
      *                          reason as {@code exhaustedPatterns} — pass {@link ExhaustionSink#none()}
      *                          to opt out.
+     *
+     * <p>Transition constructor (fleetd#201 Unit 1): delegates to the full constructor below with
+     * {@link BackendErrorPatternLookup#legacy()} and {@link BackendErrorSink#none()}, so every
+     * existing caller keeps today's behavior — the narrow built-in {@code API Error:} match, no
+     * sink notified — until a caller wires a real, profile-driven backend-error lookup and sink
+     * (fleetd#201 Unit 5).
      */
     public CompletionResolver(AgentControl agents, Rendezvous rendezvous, ExhaustedPatternLookup exhaustedPatterns,
                               ExhaustionSink exhaustionSink) {
-        this(agents, rendezvous, exhaustedPatterns, exhaustionSink, System::nanoTime);
+        this(agents, rendezvous, exhaustedPatterns, exhaustionSink,
+                BackendErrorPatternLookup.legacy(), BackendErrorSink.none(), System::nanoTime);
+    }
+
+    /**
+     * Transition constructor (fleetd#201 Unit 1): same legacy backend-error defaults as the 4-arg
+     * constructor above, but with the injectable clock. Kept so existing fleetd#164 timing tests
+     * (and any other caller that wants a controllable clock but not the backend-error feature)
+     * keep compiling unchanged.
+     */
+    public CompletionResolver(AgentControl agents, Rendezvous rendezvous, ExhaustedPatternLookup exhaustedPatterns,
+                       ExhaustionSink exhaustionSink, LongSupplier nowNanos) {
+        this(agents, rendezvous, exhaustedPatterns, exhaustionSink,
+                BackendErrorPatternLookup.legacy(), BackendErrorSink.none(), nowNanos);
+    }
+
+    /**
+     * Production constructor (fleetd#201 Unit 1): adds the target-keyed backend-error pattern
+     * lookup and sink alongside the existing exhaustion pair. Required, like {@code exhaustedPatterns}
+     * and {@code exhaustionSink} — pass {@link BackendErrorPatternLookup#legacy()} and
+     * {@link BackendErrorSink#none()} to opt out.
+     *
+     * @param backendErrorPatterns fleetd#201: per-target lookup for a profile's configured
+     *                             backend-error pattern; a target with none configured is matched
+     *                             against the built-in compatibility pattern instead (never "off").
+     * @param backendErrorSink     fleetd#201: notified when a backend-error classification actually
+     *                             resolves a waiter — never on a race that lost.
+     */
+    public CompletionResolver(AgentControl agents, Rendezvous rendezvous, ExhaustedPatternLookup exhaustedPatterns,
+                       ExhaustionSink exhaustionSink, BackendErrorPatternLookup backendErrorPatterns,
+                       BackendErrorSink backendErrorSink) {
+        this(agents, rendezvous, exhaustedPatterns, exhaustionSink, backendErrorPatterns, backendErrorSink,
+                System::nanoTime);
     }
 
     /**
@@ -145,11 +185,14 @@ public final class CompletionResolver implements TurnListener {
      * package.
      */
     public CompletionResolver(AgentControl agents, Rendezvous rendezvous, ExhaustedPatternLookup exhaustedPatterns,
-                       ExhaustionSink exhaustionSink, LongSupplier nowNanos) {
+                       ExhaustionSink exhaustionSink, BackendErrorPatternLookup backendErrorPatterns,
+                       BackendErrorSink backendErrorSink, LongSupplier nowNanos) {
         this.agents = agents;
         this.rendezvous = rendezvous;
         this.exhaustedPatterns = Objects.requireNonNull(exhaustedPatterns, "exhaustedPatterns");
         this.exhaustionSink = Objects.requireNonNull(exhaustionSink, "exhaustionSink");
+        this.backendErrorPatterns = Objects.requireNonNull(backendErrorPatterns, "backendErrorPatterns");
+        this.backendErrorSink = Objects.requireNonNull(backendErrorSink, "backendErrorSink");
         this.nowNanos = Objects.requireNonNull(nowNanos, "nowNanos");
     }
 
@@ -232,7 +275,7 @@ public final class CompletionResolver implements TurnListener {
         // screen, since that is usually the backend's own error.
         long elapsedNanos = nowNanos.getAsLong() - turn.deliveredAtNanos();
         if (elapsedNanos < MIN_TURN_NANOS) {
-            fail(target, turn, tooFastReason(target, elapsedNanos));
+            failTooFast(target, turn, waiter, elapsedNanos);
             return;
         }
         String tail;
@@ -302,18 +345,27 @@ public final class CompletionResolver implements TurnListener {
             }
             return;
         }
-        // fleetd#164 (part 2): a scrape that read cleanly and produced content still isn't a real
-        // reply when that content is the backend's own rejection (e.g. an HTTP 400 before the worker
-        // did any work). Classify it as a failure naming the member, rather than handing the caller a
-        // scrape that reads like a completed answer.
-        String backendError = firstMatchingLine(assistantBlock, BACKEND_ERROR);
+        // fleetd#164 (part 2) / fleetd#201: a scrape that read cleanly and produced content still
+        // isn't a real reply when that content is the backend's own rejection (e.g. an HTTP 400
+        // before the worker did any work). Classify it as a failure naming the member, rather than
+        // handing the caller a scrape that reads like a completed answer, and — only on the
+        // resolution that actually wins the race, mirroring the exhaustion sink above — notify the
+        // typed backend-error sink so a later stage can act on repeated failures.
+        String backendError = firstMatchingLine(assistantBlock, backendErrorPatternOrFallback(target));
         if (backendError != null) {
             // Carry the whole scrape, not just the matched line. The pattern is a heuristic: a member
             // that forgot fleet_reply while reporting *about* a backend error matches it too. Failing
             // is still right — the caller must not read a scrape as an answer — but dropping the rest
             // of the pane would destroy the report, which is the same defect fleetd#164 is about.
-            fail(target, turn, "member " + target + " ended on a backend error: " + backendError
-                    + "\n--- pane tail ---\n" + tail);
+            String reason = "member " + target + " ended on a backend error: " + backendError
+                    + "\n--- pane tail ---\n" + tail;
+            if (rendezvous.resolveFailure(waiter, reason)) {
+                inFlight.remove(target, turn);
+                log.warn("failing send to {} via turn-stall fallback: {}", target, reason);
+                // fleetd#201 Unit 1: only on the resolution that actually won the race — a late
+                // duplicate must never double-count one backend failure.
+                backendErrorSink.onBackendError(target, backendError, reason);
+            }
             return;
         }
         String completion = clipped ? tail + "\n" + CLIPPED_PANE_TAIL_MARKER : tail;
@@ -353,14 +405,20 @@ public final class CompletionResolver implements TurnListener {
             }
             return true;
         }
-        String backendError = firstMatchingLine(raw, BACKEND_ERROR);
+        String backendError = firstMatchingLine(raw, backendErrorPatternOrFallback(target));
         if (backendError != null) {
             // Carry the pane, not just the matched line — the same fleetd#164 rule the normal path
             // above applies. Here it matters more, not less: the trimmed block was empty, so the raw
             // scrape is the ONLY copy of whatever the member managed to say. Clipped to the same cap
             // the normal path uses, since a raw screen has no boundary trimming to bound it.
-            fail(target, turn, "member " + target + " ended on a backend error: " + backendError
-                    + "\n--- pane tail ---\n" + clip(raw));
+            String reason = "member " + target + " ended on a backend error: " + backendError
+                    + "\n--- pane tail ---\n" + clip(raw);
+            if (rendezvous.resolveFailure(waiter, reason)) {
+                inFlight.remove(target, turn);
+                log.warn("failing send to {} via turn-stall fallback from the raw scrape: {}", target, reason);
+                // fleetd#201 Unit 1: only on the resolution that actually won the race.
+                backendErrorSink.onBackendError(target, backendError, reason);
+            }
             return true;
         }
         return false;
@@ -402,22 +460,53 @@ public final class CompletionResolver implements TurnListener {
     }
 
     /**
-     * fleetd#164: the failure reason for a turn that settled inside {@link #MIN_TURN_NANOS} — names
-     * the member and both timings, and appends whatever the pane shows (usually the backend's own
-     * error) so the caller sees the cause, not just "it failed".
+     * fleetd#164 (floor) / fleetd#201 (classification): fail a turn that settled inside
+     * {@link #MIN_TURN_NANOS} — a crash signature (e.g. a backend HTTP 400 before the worker did
+     * anything) that a bare {@code BUSY -> DONE} transition cannot be told apart from a genuinely
+     * fast completion. Runs the same backend-error classification the normal and raw-scrape paths
+     * apply, against whatever is on screen right now: a match is a typed failure that 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".
      */
-    private String tooFastReason(String target, long elapsedNanos) {
+    private void failTooFast(String target, InFlight turn, CompletableFuture<Rendezvous.Resolution> waiter,
+                              long elapsedNanos) {
         String scrape;
         try {
-            scrape = clip(agents.read(target, SCRAPE_SOURCE));
+            scrape = agents.read(target, SCRAPE_SOURCE);
         } catch (RuntimeException e) {
             scrape = "";
         }
-        String reason = String.format(
+        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",
                 target, elapsedNanos / 1_000_000, MIN_TURN_NANOS / 1_000_000);
-        return scrape.isBlank() ? reason : reason + ": " + scrape;
+        String backendError = firstMatchingLine(scrape, backendErrorPatternOrFallback(target));
+        if (backendError != null) {
+            String reason = baseReason + ": " + clippedScrape;
+            if (rendezvous.resolveFailure(waiter, reason)) {
+                inFlight.remove(target, turn);
+                log.warn("failing send to {} via turn-stall fallback: {}", target, reason);
+                // fleetd#201 Unit 1: only on the resolution that actually won the race.
+                backendErrorSink.onBackendError(target, backendError, reason);
+            }
+            return;
+        }
+        fail(target, turn, clippedScrape.isBlank() ? baseReason : baseReason + ": " + clippedScrape);
+    }
+
+    /**
+     * fleetd#201: the pattern to classify a backend error against for {@code target} — its
+     * profile's configured {@link BackendErrorPatternLookup} entry when there is one, else the
+     * built-in {@link #BACKEND_ERROR} compatibility pattern. A target with no configured pattern is
+     * never "off": it always falls back to this narrow default, exactly like the classification
+     * behaved before fleetd#201 (Unit 5 reports a target relying on this fallback separately, as
+     * legacy-default coverage rather than full per-profile coverage).
+     */
+    private Pattern backendErrorPatternOrFallback(String target) {
+        Pattern configured = backendErrorPatterns.patternFor(target);
+        return configured != null ? configured : BACKEND_ERROR;
     }
 
     /**

fleetd/src/test/java/dev/ltms/fleet/inject/CompletionResolverTest.java

@@ -4,8 +4,11 @@ import ch.qos.logback.classic.Level;
 import ch.qos.logback.classic.LoggerContext;
 import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.core.read.ListAppender;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import dev.ltms.fleet.herdr.AgentControl;
 import dev.ltms.fleet.herdr.FakeHerdr;
+import dev.ltms.fleet.herdr.HerdrClient;
 import dev.ltms.fleet.msg.Rendezvous;
 import dev.ltms.fleet.msg.TestTurnTokens;
 import dev.ltms.fleet.msg.TurnToken;
@@ -759,4 +762,202 @@ class CompletionResolverTest {
         assertEquals("partial (configured: [terra]; not configured: [gx10])",
                 CompletionResolver.coverage(Set.of("terra", "gx10"), Set.of("terra")));
     }
+
+    // --- fleetd#201 Unit 1: target-keyed backend-error pattern + typed sink ----------------------
+
+    @Test
+    void aConfiguredBackendErrorPatternClassifiesAMatchAsAFailureAndNotifiesTheSinkOnce() {
+        String block = "⏺ 503 Service Unavailable: upstream credential rejected\n❯ ";
+        FakeHerdr herdr = new FakeHerdr().readText(block);
+        Rendezvous rendezvous = new Rendezvous();
+        BackendErrorPatternLookup patterns = target -> Pattern.compile("(?i)503 Service Unavailable");
+        java.util.List<String> notified = new java.util.ArrayList<>();
+        BackendErrorSink sink = (target, matchedLine, reason) -> notified.add(target + ": " + matchedLine);
+        CompletionResolver resolver = new CompletionResolver(new AgentControl(herdr), rendezvous,
+                ExhaustedPatternLookup.none(), ExhaustionSink.none(), patterns, sink);
+
+        var waiter = rendezvous.open("term_a");
+        resolver.resolve("term_a", new CompletionResolver.InFlight(waiter, null));
+
+        assertTrue(waiter.isDone(), "a configured-pattern match still resolves the blocked send");
+        assertEquals(Rendezvous.Kind.FAILED, waiter.getNow(null).kind());
+        assertEquals(1, notified.size(), "the sink fires exactly once for the winning classification");
+        assertEquals("term_a: 503 Service Unavailable: upstream credential rejected", notified.get(0));
+    }
+
+    @Test
+    void aLosingBackendErrorClassificationNeverNotifiesTheSink() {
+        // The waiter was already resolved (e.g. by the worker's own fleet_reply) before this scrape
+        // landed — resolveFailure loses the race and must return false, so the sink must not fire.
+        String block = "⏺ 503 Service Unavailable: upstream credential rejected\n❯ ";
+        FakeHerdr herdr = new FakeHerdr().readText(block);
+        Rendezvous rendezvous = new Rendezvous();
+        BackendErrorPatternLookup patterns = target -> Pattern.compile("(?i)503 Service Unavailable");
+        java.util.List<String> notified = new java.util.ArrayList<>();
+        BackendErrorSink sink = (target, matchedLine, reason) -> notified.add(target + ": " + matchedLine);
+        CompletionResolver resolver = new CompletionResolver(new AgentControl(herdr), rendezvous,
+                ExhaustedPatternLookup.none(), ExhaustionSink.none(), patterns, sink);
+
+        var waiter = rendezvous.open("term_a");
+        var turn = new CompletionResolver.InFlight(waiter, null);
+        assertTrue(rendezvous.resolveCompletion(waiter, "already replied")); // fleet_reply won first
+
+        resolver.resolve("term_a", turn);
+
+        assertTrue(notified.isEmpty(), "a classification that loses the race must not fire the sink");
+        assertEquals("already replied", waiter.getNow(null).text(), "the earlier resolution stands untouched");
+    }
+
+    @Test
+    void aBackendErrorClassificationThatLosesARealRaceDuringTheScrapeNeverNotifiesTheSink() {
+        // The test above pre-resolves the waiter BEFORE calling resolve(), so it is caught by
+        // resolve()'s own top-of-method isDone() guard before ever reaching the win-gated
+        // resolveFailure call this unit adds — it proves the outcome, not the specific gate. This
+        // test forces the actual race window fleetd#201 must be safe in: a genuine fleet_reply lands
+        // WHILE the herdr scrape for this turn is in flight, i.e. AFTER resolve() has already passed
+        // the top guard (waiter not done yet) and committed to reading the pane, but BEFORE it
+        // reaches the "if (rendezvous.resolveFailure(...))" line below. The side effect is attached
+        // to the one real I/O step resolve() performs between those two points: the herdr
+        // "agent.read" call itself.
+        Rendezvous rendezvous = new Rendezvous();
+        var waiter = rendezvous.open("term_a");
+        ObjectMapper mapper = new ObjectMapper();
+        HerdrClient racingDuringScrape = new HerdrClient() {
+            @Override
+            public JsonNode call(String method, Object params) {
+                if ("agent.read".equals(method)) {
+                    // The real fleet_reply that wins the race, landing mid-scrape.
+                    assertTrue(rendezvous.resolve("term_a", "a genuine fleet_reply landed first"),
+                            "the racing reply must land while the waiter is still open");
+                }
+                try {
+                    return mapper.readTree(mapper.writeValueAsString(java.util.Map.of(
+                            "type", "agent_read",
+                            "read", java.util.Map.of("text",
+                                    "⏺ 503 Service Unavailable: upstream credential rejected\n❯ "))));
+                } catch (Exception e) {
+                    throw new RuntimeException(e);
+                }
+            }
+
+            @Override
+            public void close() {
+            }
+        };
+        BackendErrorPatternLookup patterns = target -> Pattern.compile("(?i)503 Service Unavailable");
+        java.util.List<String> notified = new java.util.ArrayList<>();
+        BackendErrorSink sink = (target, matchedLine, reason) -> notified.add(target + ": " + matchedLine);
+        CompletionResolver resolver = new CompletionResolver(new AgentControl(racingDuringScrape), rendezvous,
+                ExhaustedPatternLookup.none(), ExhaustionSink.none(), patterns, sink);
+
+        var turn = new CompletionResolver.InFlight(waiter, null); // not done yet — passes the top guard
+        resolver.resolve("term_a", turn);
+
+        assertTrue(notified.isEmpty(),
+                "a classification that loses a real race during the scrape must not fire the sink");
+        assertEquals(Rendezvous.Kind.REPLY, waiter.getNow(null).kind(), "the genuine fleet_reply stands");
+        assertEquals("a genuine fleet_reply landed first", waiter.getNow(null).text());
+    }
+
+    @Test
+    void exhaustionKeepsWinningOverBackendErrorEvenWhenBothPatternsMatchTheSameLine() {
+        // A line matching both a configured exhausted pattern AND a configured backend-error pattern
+        // must classify BACKEND_EXHAUSTED and call only the ExhaustionSink — the ordering fleetd#578
+        // already relies on must not change.
+        String block = "⏺ The usage limit has been reached. Try again later.\n❯ ";
+        FakeHerdr herdr = new FakeHerdr().readText(block);
+        Rendezvous rendezvous = new Rendezvous();
+        ExhaustedPatternLookup exhausted = target -> Pattern.compile("usage limit has been reached");
+        BackendErrorPatternLookup backendErrors = target -> Pattern.compile("(?i)usage limit");
+        java.util.List<String> exhaustedNotified = new java.util.ArrayList<>();
+        java.util.List<String> backendErrorNotified = new java.util.ArrayList<>();
+        ExhaustionSink exhaustionSink = (target, reason) -> exhaustedNotified.add(target);
+        BackendErrorSink backendErrorSink = (target, matchedLine, reason) -> backendErrorNotified.add(target);
+        CompletionResolver resolver = new CompletionResolver(new AgentControl(herdr), rendezvous,
+                exhausted, exhaustionSink, backendErrors, backendErrorSink);
+
+        var waiter = rendezvous.open("term_a");
+        resolver.resolve("term_a", new CompletionResolver.InFlight(waiter, null));
+
+        assertEquals(Rendezvous.Kind.BACKEND_EXHAUSTED, waiter.getNow(null).kind(),
+                "exhaustion must keep winning over backend error");
+        assertEquals(1, exhaustedNotified.size(), "the exhaustion sink fires");
+        assertTrue(backendErrorNotified.isEmpty(), "the backend-error sink must never fire for this turn");
+    }
+
+    @Test
+    void aConfiguredPatternAlsoClassifiesTheRawScrapeFallbackAndNotifiesTheSink() {
+        // No ⏺ marker and leading TUI chrome ⇒ lastAssistantBlock() yields "", so classification must
+        // fall back to the raw scrape (fleetd#211) — and it must use the configured pattern too.
+        String block = """
+                ╭──────────────────────────────────────╮
+                503 Service Unavailable: upstream credential rejected
+                """;
+        FakeHerdr herdr = new FakeHerdr().readText(block);
+        Rendezvous rendezvous = new Rendezvous();
+        BackendErrorPatternLookup patterns = target -> Pattern.compile("(?i)503 Service Unavailable");
+        java.util.List<String> notified = new java.util.ArrayList<>();
+        BackendErrorSink sink = (target, matchedLine, reason) -> notified.add(target + ": " + matchedLine);
+        CompletionResolver resolver = new CompletionResolver(new AgentControl(herdr), rendezvous,
+                ExhaustedPatternLookup.none(), ExhaustionSink.none(), patterns, sink);
+
+        var waiter = rendezvous.open("term_a");
+        resolver.resolve("term_a", new CompletionResolver.InFlight(waiter, null));
+
+        assertTrue(waiter.isDone(), "a raw-scrape configured-pattern match still resolves the blocked send");
+        assertEquals(Rendezvous.Kind.FAILED, waiter.getNow(null).kind(),
+                "classified from the raw scrape even though the trimmed block was empty");
+        assertEquals(1, notified.size(), "the sink fires exactly once from the raw-scrape path");
+        assertTrue(notified.get(0).contains("503 Service Unavailable"), notified.get(0));
+    }
+
+    // --- fleetd#201 Unit 1: classification inside the fleetd#164 MIN_TURN_NANOS floor -------------
+
+    @Test
+    void aMatchingErrorInsideTheFloorIsTypedAndNotifiesTheSink() {
+        FakeHerdr herdr = new FakeHerdr().readText("⏺ 503 Service Unavailable: upstream credential rejected\n❯ ");
+        Rendezvous rendezvous = new Rendezvous();
+        long[] clock = {10_000_000_000L};
+        BackendErrorPatternLookup patterns = target -> Pattern.compile("(?i)503 Service Unavailable");
+        java.util.List<String> notified = new java.util.ArrayList<>();
+        BackendErrorSink sink = (target, matchedLine, reason) -> notified.add(target + ": " + matchedLine);
+        CompletionResolver resolver = new CompletionResolver(new AgentControl(herdr), rendezvous,
+                ExhaustedPatternLookup.none(), ExhaustionSink.none(), patterns, sink, () -> clock[0]);
+
+        var waiter = rendezvous.open("term_a");
+        var turn = new CompletionResolver.InFlight(waiter, null, clock[0]); // delivered "now"
+        clock[0] += CompletionResolver.MIN_TURN_NANOS - 1; // inside the floor
+
+        resolver.resolve("term_a", turn);
+
+        assertTrue(waiter.isDone());
+        assertEquals(Rendezvous.Kind.FAILED, waiter.getNow(null).kind());
+        assertEquals(1, notified.size(), "a matching error inside the floor notifies the sink");
+        assertTrue(notified.get(0).contains("503 Service Unavailable"), notified.get(0));
+    }
+
+    @Test
+    void aNonMatchInsideTheFloorStaysGenericAndNeverNotifiesTheSink() {
+        FakeHerdr herdr = new FakeHerdr().readText("⏺ still starting up\n❯ ");
+        Rendezvous rendezvous = new Rendezvous();
+        long[] clock = {10_000_000_000L};
+        BackendErrorPatternLookup patterns = target -> Pattern.compile("(?i)503 Service Unavailable");
+        java.util.List<String> notified = new java.util.ArrayList<>();
+        BackendErrorSink sink = (target, matchedLine, reason) -> notified.add(target + ": " + matchedLine);
+        CompletionResolver resolver = new CompletionResolver(new AgentControl(herdr), rendezvous,
+                ExhaustedPatternLookup.none(), ExhaustionSink.none(), patterns, sink, () -> clock[0]);
+
+        var waiter = rendezvous.open("term_a");
+        var turn = new CompletionResolver.InFlight(waiter, null, clock[0]); // delivered "now"
+        clock[0] += CompletionResolver.MIN_TURN_NANOS - 1; // inside the floor
+
+        resolver.resolve("term_a", turn);
+
+        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());
+        assertTrue(notified.isEmpty(), "a non-match must never notify the typed sink");
+    }
 }