fleetd must not let the host idle-sleep while members are live

Adds a small IdleSleepGuard (dev.ltms.fleet.power) that holds a macOS
caffeinate -i child while at least one fleet member is live, and
releases it once none are. It hangs off SessionManager's existing
onAcquire/onRelease hooks and SessionManager#size() rather than
tracking members a second way. New idleSleepGuard: config block,
on by default, following the FleetConfig.Health/ConfigReload pattern.

fleetd/fleetd.example.yaml

@@ -110,6 +110,14 @@ bind:
 #   notifications:
 #     mode: disabled
 
+# Idle-sleep guard: while at least one member is live, hold an OS-level assertion against idle
+# sleep (macOS only — a `caffeinate -i` child; a no-op elsewhere or if caffeinate is missing), so
+# an unattended host does not idle-sleep out from under a member's long turn. Unlike health/
+# configReload above, this is ON BY DEFAULT — omitting the block entirely leaves it enabled, the
+# same as `enabled: true`. Uncomment only to turn it off:
+# idleSleepGuard:
+#   enabled: false
+
 # herdr Unix socket. Omit to use the client default
 # (${HERDR_SOCKET_PATH:-~/.config/herdr/herdr.sock}).
 herdrSocket: ~/.config/herdr/herdr.sock

fleetd/src/main/java/dev/ltms/fleet/Fleetd.java

@@ -55,6 +55,8 @@ import dev.ltms.fleet.member.MemberCredentialPolicyView;
 import dev.ltms.fleet.member.OpenCodeLauncher;
 import dev.ltms.fleet.placement.BackendOutagePolicy;
 import dev.ltms.fleet.placement.BackendQuarantine;
+import dev.ltms.fleet.power.CaffeinateSleepAssertionMechanism;
+import dev.ltms.fleet.power.IdleSleepGuard;
 import io.javalin.Javalin;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -252,6 +254,26 @@ public final class Fleetd {
                 System::nanoTime, contextCap, clearAfterTurn);
         liveCountRef.set(profileName -> liveSessionCount(sessions.roster(), profileName));
 
+        // Idle-sleep guard: hold an OS-level assertion against idle sleep while at least one
+        // member is live, so an unattended host does not idle-sleep out from under a member's
+        // long turn (see FleetConfig.IdleSleepGuard / dev.ltms.fleet.power.IdleSleepGuard for the
+        // measurement that motivated this). Opt-out via idleSleepGuard.enabled: false; on by
+        // default. Hangs off SessionManager's own onAcquire/onRelease hooks (CB-520/CB-516,
+        // previously wired only to the reply inbox) and SessionManager#size() — the exact registry
+        // fleet_list's live/capacity numbers are themselves computed from — rather than tracking
+        // members a second way. No-op (never constructed) off macOS or when idleSleepGuard.enabled
+        // is explicitly false; the mechanism itself is additionally a no-op if 'caffeinate' cannot
+        // be started, so this can never fail a spawn, a release, or startup.
+        boolean idleSleepGuardEnabled = cfg.idleSleepGuard() == null || cfg.idleSleepGuard().isEnabled();
+        final IdleSleepGuard idleSleepGuard;
+        if (idleSleepGuardEnabled) {
+            idleSleepGuard = new IdleSleepGuard(new CaffeinateSleepAssertionMechanism(), sessions::size);
+            sessions.onAcquire(_ -> idleSleepGuard.recheck());
+            sessions.onRelease(_ -> idleSleepGuard.recheck());
+        } else {
+            idleSleepGuard = null;
+        }
+
         // CB-303 part 1: idle-ttl reaper — only when configured, defaults to disabled.
         final SessionReaper reaper;
         if (cfg.lifecycle() != null
@@ -698,6 +720,11 @@ public final class Fleetd {
             if (configWatcher != null) configWatcher.stop(); // CB-559: stop polling the config file
             mcp.close();
             if (reaper != null) reaper.stop();
+            // Idle-sleep guard: release unconditionally, even though sessions.close() above already
+            // drained every session (and each release already drove the live count to 0, which
+            // releases the guard's assertion on its own) — this is the backstop for a drain that was
+            // itself interrupted or threw, so no caffeinate child ever outlives the daemon.
+            if (idleSleepGuard != null) idleSleepGuard.close();
             // Release the broker connection last among message resources (no-op for the in-memory inbox).
             if (replyInbox instanceof AutoCloseable closeable) {
                 try {

fleetd/src/main/java/dev/ltms/fleet/config/ConfigRef.java

@@ -37,6 +37,10 @@ import java.util.function.Supplier;
  *       makes {@code fleet:} split rather than hot — see below.</li>
  *   <li><strong>Deferred</strong> — accepted into the new snapshot, but the wiring built at startup
  *       keeps the old value until a restart: {@code lifecycle:}, {@code leadHeartbeat:},
+ *       {@code idleSleepGuard:} ({@code Fleetd.java} reads it once, at startup, to decide whether
+ *       to construct an {@code IdleSleepGuard} and wire {@code SessionManager}'s
+ *       {@code onAcquire}/{@code onRelease} hooks to it — neither is rebuilt on reload, so a
+ *       running daemon keeps whatever this was at startup regardless of a later edit),
  *       {@code spawnReadyTimeoutMs} / {@code spawnReadyPollMs}, {@code quarantineCooldownSeconds}
  *       (CB-578 stage B — baked once into the {@code BackendQuarantine} built at startup),
  *       {@code guard:}, {@code worktreeRoot:} and {@code worktreeGroup:} (both baked once into the
@@ -129,8 +133,9 @@ import java.util.function.Supplier;
  *       five of COLD_KEYS" rather than re-listing them, so prose and set cannot drift again.</li>
  * </ul>
  *
- * <p><strong>The denominator, measured on 2026-09-04 (fleetd #330; recounted for fleetd #333).</strong>
- * {@code FleetConfig} has 22 top-level record components: 5 cold, 11 deferred, 3 split, 3
+ * <p><strong>The denominator, measured on 2026-09-04 (fleetd #330; recounted for fleetd #333),
+ * recounted again after {@code idleSleepGuard:} was added.</strong>
+ * {@code FleetConfig} has 23 top-level record components: 5 cold, 12 deferred, 3 split, 3
  * hot-excluded. Three of them are named nowhere in this file, and the reason is the same for all
  * three: {@code placement}, {@code memberCredentials} and {@code memberLoginShell} are
  * <strong>hot</strong> and correctly absent — all three are read live off {@code config.get()}
@@ -213,7 +218,7 @@ public final class ConfigRef implements Supplier<FleetConfig> {
     static final Set<String> DEFERRED_KEYS = Set.of(
             "guard", "worktreeRoot", "worktreeGroup", "primary", "configReload",
             "leadHeartbeat", "lifecycle", "spawnReadyTimeoutMs", "spawnReadyPollMs",
-            "quarantineCooldownSeconds", "profiles");
+            "quarantineCooldownSeconds", "profiles", "idleSleepGuard");
 
     private final Path path;
     private final AtomicReference<FleetConfig> current;
@@ -418,6 +423,14 @@ public final class ConfigRef implements Supplier<FleetConfig> {
         if (!Objects.equals(old.configReload(), fresh.configReload())) {
             changed.add("configReload");
         }
+        // Fleetd.java reads cfg.idleSleepGuard() once, at startup, to decide whether to construct
+        // an IdleSleepGuard at all and wire SessionManager's onAcquire/onRelease hooks to it —
+        // neither is rebuilt on reload, so a running daemon keeps whatever this was at startup
+        // (armed or not) regardless of a later edit here. Not cold: nothing already-open goes
+        // inconsistent with the new value, an armed-or-not guard just keeps its original answer.
+        if (!Objects.equals(old.idleSleepGuard(), fresh.idleSleepGuard())) {
+            changed.add("idleSleepGuard");
+        }
         if (!Objects.equals(old.spawnReadyTimeoutMs(), fresh.spawnReadyTimeoutMs())
                 || !Objects.equals(old.spawnReadyPollMs(), fresh.spawnReadyPollMs())) {
             changed.add("spawnReady*");

fleetd/src/main/java/dev/ltms/fleet/config/FleetConfig.java

@@ -106,6 +106,11 @@ import java.util.regex.PatternSyntaxException;
  *                      When {@code memberHerdrSocket} is NOT configured this field is never
  *                      consulted at all; fleetd keeps reading its own {@code $SHELL}, exactly as
  *                      before this field existed.
+ * @param idleSleepGuard opt-in-by-default: hold an OS-level assertion against idle sleep while at
+ *                      least one member is live, so an unattended host does not sleep out from
+ *                      under a member's long turn. {@code null} (the block omitted) behaves the
+ *                      same as an explicit {@code enabled: true}; set {@code enabled: false} to
+ *                      turn it off. See {@link dev.ltms.fleet.power.IdleSleepGuard}.
  */
 @JsonIgnoreProperties(ignoreUnknown = true)
 public record FleetConfig(
@@ -130,7 +135,22 @@ public record FleetConfig(
         MemberCredentials memberCredentials,
         Coordinator coordinator,
         String worktreeGroup,
-        String memberLoginShell) {
+        String memberLoginShell,
+        IdleSleepGuard idleSleepGuard) {
+
+    /** Back-compat form before the {@code idleSleepGuard:} block was added. */
+    public FleetConfig(Bind bind, String herdrSocket, String memberHerdrSocket, Map<String, Profile> profiles,
+                         Guard guard, String worktreeRoot, Lifecycle lifecycle, Integer spawnReadyTimeoutMs,
+                         Integer spawnReadyPollMs, Broker broker, Primary primary, Fleet fleet,
+                         LeadHeartbeat leadHeartbeat, Health health, String placement, Auth auth,
+                         ConfigReload configReload, Integer quarantineCooldownSeconds,
+                         MemberCredentials memberCredentials, Coordinator coordinator, String worktreeGroup,
+                         String memberLoginShell) {
+        this(bind, herdrSocket, memberHerdrSocket, profiles, guard, worktreeRoot, lifecycle, spawnReadyTimeoutMs,
+                spawnReadyPollMs, broker, primary, fleet, leadHeartbeat, health, placement, auth,
+                configReload, quarantineCooldownSeconds, memberCredentials, coordinator, worktreeGroup,
+                memberLoginShell, null);
+    }
 
     /** Back-compat form before the {@code memberLoginShell} key was added. */
     public FleetConfig(Bind bind, String herdrSocket, String memberHerdrSocket, Map<String, Profile> profiles,
@@ -141,7 +161,7 @@ public record FleetConfig(
                          MemberCredentials memberCredentials, Coordinator coordinator, String worktreeGroup) {
         this(bind, herdrSocket, memberHerdrSocket, profiles, guard, worktreeRoot, lifecycle, spawnReadyTimeoutMs,
                 spawnReadyPollMs, broker, primary, fleet, leadHeartbeat, health, placement, auth,
-                configReload, quarantineCooldownSeconds, memberCredentials, coordinator, worktreeGroup, null);
+                configReload, quarantineCooldownSeconds, memberCredentials, coordinator, worktreeGroup, null, null);
     }
 
     /** Back-compat form before the {@code worktreeGroup} key was added. */
@@ -1245,6 +1265,25 @@ public record FleetConfig(
         }
     }
 
+    /**
+     * Hold an OS-level assertion against idle sleep while at least one member is live (see
+     * {@link dev.ltms.fleet.power.IdleSleepGuard}).
+     *
+     * <p>Unlike most opt-in blocks in this file, this one defaults to <em>on</em>: an unattended
+     * host idle-sleeping mid-turn is a correctness problem (a dropped AMQP link, a frozen member),
+     * not a convenience, so the safer default is armed. An operator who wants the previous
+     * behaviour (no assertion held, ever) sets {@code enabled: false} explicitly.
+     *
+     * @param enabled {@code false} turns the guard off; {@code null} (the block omitted
+     *                entirely) or {@code true} leaves it on
+     */
+    @JsonIgnoreProperties(ignoreUnknown = true)
+    public record IdleSleepGuard(Boolean enabled) {
+        public boolean isEnabled() {
+            return !Boolean.FALSE.equals(enabled);
+        }
+    }
+
     /**
      * The terminal → lead-name map seeded from the legacy singular {@code primary:} pin (CB-530).
      *
@@ -1495,7 +1534,7 @@ public record FleetConfig(
             "bind", "herdrSocket", "memberHerdrSocket", "profiles", "guard", "worktreeRoot",
             "lifecycle", "spawnReadyTimeoutMs", "spawnReadyPollMs", "broker", "primary", "fleet",
             "leadHeartbeat", "health", "placement", "auth", "configReload", "quarantineCooldownSeconds",
-            "memberCredentials", "coordinator", "worktreeGroup", "memberLoginShell");
+            "memberCredentials", "coordinator", "worktreeGroup", "memberLoginShell", "idleSleepGuard");
 
     /** Load and validate config from {@code path}. */
     public static FleetConfig load(Path path) {
@@ -2172,9 +2211,14 @@ public record FleetConfig(
         // memberLoginShell is left as-is (fleetd #213), like worktreeGroup: null/blank is "not
         // configured", and there is no sane non-null default — a member's login shell is
         // operator-specific and only meaningful when memberHerdrSocket is also set.
+        // idleSleepGuard is left as-is, like leadHeartbeat/configReload above, but for the opposite
+        // reason: it is on by default already (its own isEnabled() treats null the same as
+        // enabled: true — see its javadoc), so defaulting the block here would change nothing a
+        // reader observes and would only obscure that "block omitted" and "block present and
+        // enabled" are deliberately the same outcome.
         return new FleetConfig(b, herdrSocket, memberHerdrSocket, profiles, g, worktreeRoot, l, timeout, pollMs,
                 broker, primary, f, leadHeartbeat, health, placementOrDefault, a, configReload,
-                quarantineCooldown, mc, coordinator, worktreeGroup, memberLoginShell);
+                quarantineCooldown, mc, coordinator, worktreeGroup, memberLoginShell, idleSleepGuard);
     }
 
     /**

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

@@ -380,7 +380,9 @@ public final class CompletionResolver implements TurnListener {
                         + "matched the profile's exhausted pattern): {}", target, reason);
                 // CB-578 stage B: only on the resolution that actually won the race — a late
                 // duplicate must never quarantine a credential twice for one refusal.
-                exhaustionSink.onExhausted(target, reason);
+                if (startsWithExhaustion(matchedLine, exhausted)) {
+                    exhaustionSink.onExhausted(target, reason);
+                }
             }
             return;
         }
@@ -478,7 +480,9 @@ public final class CompletionResolver implements TurnListener {
                         + "usable assistant block; no fleet_reply): {}", target, reason);
                 // CB-578 stage B: only on the resolution that actually won the race — a late
                 // duplicate must never quarantine a credential twice for one refusal.
-                exhaustionSink.onExhausted(target, reason);
+                if (startsWithExhaustion(matchedLine, exhausted)) {
+                    exhaustionSink.onExhausted(target, reason);
+                }
             }
             return true;
         }
@@ -613,6 +617,46 @@ public final class CompletionResolver implements TurnListener {
         return null;
     }
 
+    /**
+     * True when nothing before the match on this pane line ends a sentence — that is, the match is
+     * still inside the line's first sentence rather than inside prose a member wrote about it.
+     * Used to decide whether an exhaustion match may quarantine a credential (fleetd #348).
+     *
+     * <p><strong>Why this is looser than {@link #startsWithBackendError}.</strong> An
+     * {@code exhaustedPattern} is written per profile and may name only the decisive words of a
+     * provider message — {@code "usage limit has been reached"} without its leading {@code "The"}.
+     * A start-of-line check would then reject the genuine refusal. That is the false negative
+     * fleetd #348's invariant 1 calls the worse direction: an unrecorded exhaustion leaves the
+     * fleet spawning into a credential with no capacity, and a quarantine runs 1800s against the
+     * backend-error cooldown's fixed 60s.
+     *
+     * <p>This rule accepts a superset of what a start-of-line check accepts: if the match begins
+     * right after the chrome, there is nothing in front of it, so there is no sentence ending
+     * either. So moving to it cannot add a false negative.
+     *
+     * <p><strong>No chrome skipping here, deliberately.</strong> The first version of this method
+     * copied {@code startsWithBackendError}'s leading-chrome loop. Measured on merge: deleting that
+     * loop left all 1369 tests green, and it must — the scan only looks for {@code . ! ?}, and no
+     * terminal chrome character is one of those. A step that cannot change the result is worse than
+     * no step, because the next reader takes it as evidence that chrome was handled.
+     *
+     * <p>It stays a heuristic. Prose whose <em>first</em> sentence carries the pattern still
+     * notifies the sink, and a genuine refusal behind an earlier full stop (a hostname, a version
+     * number) still does not. Both are known and neither is fixed here.
+     */
+    private static boolean startsWithExhaustion(String line, Pattern pattern) {
+        var matcher = pattern.matcher(line);
+        if (!matcher.find()) {
+            return false;
+        }
+        for (int prefix = 0; prefix < matcher.start(); prefix++) {
+            if (".!?".indexOf(line.charAt(prefix)) >= 0) {
+                return false;
+            }
+        }
+        return true;
+    }
+
     /**
      * True when the error pattern begins the matched pane line, rather than appearing in prose.
      *

fleetd/src/main/java/dev/ltms/fleet/msg/MessageService.java

@@ -709,27 +709,47 @@ public final class MessageService {
             boolean isRecovery = task == recoveryTask && recovered != null;
             Reply outcome = isRecovery ? recovered : new Reply(Outcome.WORKER_FAILED, reason);
             String turnId = task.turnId;
-            if (task.future.complete(outcome)) {
-                if (outcome.outcome() == Outcome.WORKER_FAILED) {
-                    asyncFailed = true;
+            // fleetd #335: completing THIS task's future must not depend on any other task's
+            // cleanup succeeding — every task in `matching` is owed its own outcome regardless of
+            // what happens below, so decide and record that before doing anything that can throw.
+            boolean completedHere = task.future.complete(outcome);
+            if (completedHere && outcome.outcome() == Outcome.WORKER_FAILED) {
+                asyncFailed = true;
+            }
+            try {
+                if (abandonCleanupHookForTest != null) {
+                    // Test-only (fleetd #335 site 1): see the field's own javadoc.
+                    abandonCleanupHookForTest.run();
                 }
-                if (turnId != null) {
-                    // #275: whether this task was swept out of ASKING or was already answered and
-                    // only waiting on its resumed turn's real reply (#137), nothing will ever
-                    // complete this turnId now — drop it from this class's own bookkeeping AND the
-                    // reverse-rendezvous itself, so hasAsyncQuestion(target) stops reporting a turn
-                    // that is actually done, and a late answer() sees it as lapsed rather than
-                    // resolving a question nothing is listening for any more.
-                    asyncTasksByTurn.remove(turnId, task);
-                    rendezvous.closeAsk(turnId);
+                if (completedHere) {
+                    if (turnId != null) {
+                        // #275: whether this task was swept out of ASKING or was already answered and
+                        // only waiting on its resumed turn's real reply (#137), nothing will ever
+                        // complete this turnId now — drop it from this class's own bookkeeping AND the
+                        // reverse-rendezvous itself, so hasAsyncQuestion(target) stops reporting a turn
+                        // that is actually done, and a late answer() sees it as lapsed rather than
+                        // resolving a question nothing is listening for any more.
+                        asyncTasksByTurn.remove(turnId, task);
+                        rendezvous.closeAsk(turnId);
+                    }
+                } else if (isRecovery) {
+                    // The recovered reply was already drained out of the inbox, but this task resolved
+                    // through another path (e.g. a concurrent reply() or a second abandon() racing this
+                    // one) between us choosing it and completing it here. Put the reply back rather than
+                    // lose it silently — it may still belong to some other still-open task, or the next
+                    // caller that drains this target's inbox.
+                    inbox.publish(target, UUID.randomUUID().toString(), recovered.text());
                 }
-            } else if (isRecovery) {
-                // The recovered reply was already drained out of the inbox, but this task resolved
-                // through another path (e.g. a concurrent reply() or a second abandon() racing this
-                // one) between us choosing it and completing it here. Put the reply back rather than
-                // lose it silently — it may still belong to some other still-open task, or the next
-                // caller that drains this target's inbox.
-                inbox.publish(target, UUID.randomUUID().toString(), recovered.text());
+            } catch (RuntimeException e) {
+                // fleetd #335: inbox.publish reaches a broker (AmqpReplyInbox throws
+                // IllegalStateException on an unroutable/unconfirmed/interrupted publish) and this
+                // loop has no other teardown path — a caller on the release path, or the health
+                // monitor's GONE/NEVER_READY sweep. Losing this exception uncaught would abort the
+                // loop and leave every task still to come in `matching` PENDING forever (fleetd
+                // #335 site 1). completedHere is already recorded above, so only this task's
+                // best-effort bookkeeping is lost — log it and let the loop reach the rest.
+                log.error("abandon: per-task cleanup failed for ticket {} (target {}, turnId {})",
+                        task.ticket, target, turnId, e);
             }
         }
         if (failed) {
@@ -871,6 +891,10 @@ public final class MessageService {
                     boolean wasDelivered = delivery.completion().isDone()
                             && !delivery.completion().isCompletedExceptionally();
                     if (!wasDelivered) {
+                        if (timeoutCancellationRaceHookForTest != null) {
+                            // Test-only (fleetd #345): see the field's own javadoc.
+                            timeoutCancellationRaceHookForTest.run();
+                        }
                         // The target monitor makes cancellation atomic with onStatus picking this
                         // Pending up. If pickup won, report TIMED_OUT_WORKING because the text landed.
                         wasDelivered = injector.cancel(delivery) == Injector.Cancellation.DELIVERED;
@@ -941,13 +965,41 @@ public final class MessageService {
             return new AskResult(AskOutcome.ANSWERED, answer);
         } catch (TimeoutException e) {
             log.debug("fleet_ask from {} went unanswered in {}ms", workerSession, timeoutMillis);
-            // fleetd #307: mark the task BEFORE clearAsyncQuestion(forgetTurn=true) below drops it out of
-            // asyncTasksByTurn and nulls its turnId — that forgetting is deliberate and stays (it is
-            // what keeps the target from staying BUSY forever), but it would otherwise also erase
-            // askAnsweredAsyncTasks' only signal that the worker's eventual real fleet_reply still
-            // belongs to this task, stranding it in the inbox with a false "never replied" verdict.
-            markAskTimedOut(ticket.turnId());
-            clearAsyncQuestion(ticket.turnId(), true);
+            // Only the fresh owner tears down the shared turn (mirrors the finally block below).
+            // A duplicate's own timeoutMillis says nothing about whether the SHARED ask is actually
+            // done — it must leave the close/forget bookkeeping to the fresh owner, exactly as it
+            // already leaves closeAsk to it.
+            if (ticket.fresh()) {
+                // fleetd #334: close the ask turn BEFORE forgetting this task's turnId mapping below.
+                // Before this fix the order was reversed — the mapping was forgotten here first, and
+                // rendezvous.closeAsk only ran afterward, in the shared finally. A primary's answer()
+                // call racing this exact timeout could then find rendezvous.askSession(turnId) still
+                // non-null (the ask still "answerable") after the Task mapping was already gone:
+                // answer()'s own asyncTasksByTurn lookup returned null, its task != null guard skipped
+                // the completion, and the async ticket sat at PENDING forever even though answer()
+                // itself reported the worker's real reply. Closing here first removes that window:
+                // any answer() call that still observes askSession(turnId) != null is necessarily
+                // racing a point BEFORE the forgetting below runs (both happen on this one thread, in
+                // this order, with nothing that yields in between), so the Task mapping is still there
+                // for it to find; any call that observes askSession(turnId) == null now correctly
+                // bails out STALE_TURN (see answer()'s own top check) before ever reaching
+                // asyncTasksByTurn. rendezvous.closeAsk is idempotent — a no-op once the turn is
+                // already removed, see its own javadoc — so the shared finally below re-running it
+                // for this same fresh call is harmless.
+                rendezvous.closeAsk(ticket.turnId());
+                if (askTimeoutRaceHookForTest != null) {
+                    // Test-only (fleetd #334): see the field's own javadoc.
+                    askTimeoutRaceHookForTest.run();
+                }
+                // fleetd #307: mark the task BEFORE clearAsyncQuestion(forgetTurn=true) below drops it
+                // out of asyncTasksByTurn and nulls its turnId — that forgetting is deliberate and
+                // stays (it is what keeps the target from staying BUSY forever), but it would
+                // otherwise also erase askAnsweredAsyncTasks' only signal that the worker's eventual
+                // real fleet_reply still belongs to this task, stranding it in the inbox with a false
+                // "never replied" verdict.
+                markAskTimedOut(ticket.turnId());
+                clearAsyncQuestion(ticket.turnId(), true);
+            }
             return new AskResult(AskOutcome.TIMED_OUT, null);
         } catch (ExecutionException e) {
             Throwable cause = e.getCause();
@@ -1046,19 +1098,28 @@ public final class MessageService {
                 // the chained ask deliberately left open.
                 //
                 // A null task is NOT only "this was never an async ticket". That reading was in this
-                // comment when #329 merged and it is wrong. A genuine async ticket also lands here
-                // with task == null, because ask()'s timeout path runs clearAsyncQuestion(turnId,
-                // true) — which drops the asyncTasksByTurn entry — in its catch block, while
-                // rendezvous.closeAsk(turnId) runs later, in its finally. Between those two the ask
-                // is still answerable but the map entry is already gone, so the lookup at :991
-                // returns null and this ticket is never completed. Measured on 2026-09-04: a probe
-                // firing only that first half before answer() runs printed
-                // "answer=REPLIED phase=PENDING reply=null" — the same stranded ticket #329 set out
-                // to fix, one step earlier in the same race. The probe used forgetTurnForTest, which
-                // omits ask()'s markAskTimedOut; that cannot change the outcome, because askTimedOut
-                // is read only by askAnsweredAsyncTasks, and reply() never reaches it while this
-                // method's own waiter is live. So #329 narrows this window rather than closing it.
-                // Open as fleetd #334 — do not read this guard as complete.
+                // comment when #329 merged and it is wrong; it is still not the whole story after
+                // #334. A genuine async ticket can still land here with task == null — a blocking
+                // (wait:true) send's fleet_ask never has a Task at all, so that case is expected and
+                // fine. What #334 fixed was a SECOND, unintended way to get here with task == null:
+                // ask()'s timeout path used to run clearAsyncQuestion(turnId, true) — which drops the
+                // asyncTasksByTurn entry — in its catch block, while rendezvous.closeAsk(turnId) ran
+                // later, in its finally. Between those two the ask was still answerable but the map
+                // entry was already gone, so the lookup at :1053 returned null and this ticket was
+                // never completed. Measured on 2026-09-04: a probe firing only that first half before
+                // answer() ran printed "answer=REPLIED phase=PENDING reply=null" — the same stranded
+                // ticket #329 set out to fix, one step earlier in the same race; the probe used
+                // forgetTurnForTest, which omits ask()'s markAskTimedOut, and that omission does not
+                // change the outcome, because askTimedOut is read only by askAnsweredAsyncTasks, and
+                // reply() never reaches it while this method's own waiter is live. #334's fix
+                // reorders ask()'s timeout catch to run closeAsk before the forgetting (see the
+                // fresh-owner block there), which removes this path entirely rather than narrowing
+                // it further: once closeAsk has run, rendezvous.askSession(turnId) is null and
+                // answer() returns STALE_TURN from its own top check, before it ever reaches this
+                // lookup — see aLateAnswerDuringAskTimeoutTeardownStillCompletesTheAsyncTicket in
+                // MessageServiceTest, which pins the exact window with askTimeoutRaceHookForTest.
+                // So by the time this line runs, task == null means only the ordinary blocking-send
+                // case (or #329's own already-fixed race elsewhere) — not this one.
                 if (result.outcome() != Outcome.QUESTION && task != null) {
                     finishAsyncTask(task, result);
                 }
@@ -1118,7 +1179,18 @@ public final class MessageService {
             // class javadoc on sendAsync/CB-107.
             task.future.whenComplete((reply, ex) -> {
                 boolean failed = ex != null || reply == null || !reply.completed();
-                pushLoop.onTicketTerminal(ticket, target, failed);
+                try {
+                    pushLoop.onTicketTerminal(ticket, target, failed);
+                } catch (Throwable t) {
+                    // fleetd #335 (site 2): this stage's own CompletableFuture is discarded, so an
+                    // uncaught throw here (e.g. a RejectedExecutionException from
+                    // ReplyPushLoop's scheduler, already shut down while this in-flight send's
+                    // whenComplete fires during the daemon's own shutdown sequence — messages.close()
+                    // only stops accepting NEW async work, it does not cancel a delivery already
+                    // running) vanishes with no log line and no metric, and the push loop never learns
+                    // the ticket went terminal — the exact thing this hook exists to tell it.
+                    log.error("push loop failed to learn ticket {} (target {}) went terminal", ticket, target, t);
+                }
             });
         }
         asyncExecutor.submit(() -> {
@@ -1370,6 +1442,24 @@ public final class MessageService {
         this.afterFinishAsyncTaskCompleteHookForTest = hook;
     }
 
+    /**
+     * Null in production; test seam for fleetd #345 — invoked in {@link #send}'s timeout path after
+     * {@link Injector.Delivery#completion()} reports incomplete and before {@link Injector#cancel}
+     * takes the target monitor. A test installs this to make {@code onStatus} pick the exact queued
+     * delivery up in that window, so {@code cancel} returns {@link Injector.Cancellation#DELIVERED}.
+     * This deterministically covers the caller's need to use that result rather than relying on a
+     * timing-sensitive real race.
+     */
+    private volatile Runnable timeoutCancellationRaceHookForTest;
+
+    /**
+     * Test-only (fleetd #345): install {@link #timeoutCancellationRaceHookForTest}. Package-private
+     * so the test, in the same package, can reach it without widening any production API.
+     */
+    void setTimeoutCancellationRaceHookForTest(Runnable hook) {
+        this.timeoutCancellationRaceHookForTest = hook;
+    }
+
     /**
      * Null in production; test seam for fleetd #329 (F3) — invoked from {@link #reply} right after
      * the single local read of {@code orphan.turnId} passes its null-check and before that (now-local)
@@ -1399,6 +1489,56 @@ public final class MessageService {
         clearAsyncQuestion(turnId, true);
     }
 
+    /**
+     * Null in production; test seam for fleetd #335 (site 1) — invoked from {@link #abandon(String,
+     * String, boolean)}'s per-task loop, once per task, right before that task's own cleanup
+     * (turnId bookkeeping, or the stranded-reply put-back) runs. A test installs this to inject a
+     * throw at that exact point deterministically.
+     *
+     * <p>The one production call there that can really throw is {@code inbox.publish} in the
+     * put-back branch — {@link AmqpReplyInbox#publish} reaches a broker and throws {@link
+     * IllegalStateException} on an unroutable, unconfirmed, or interrupted publish — but reaching
+     * that branch requires a second completion of the very task {@code abandon} is about to
+     * complete to win the race first (see the branch's own comment), and the #137 follow-up
+     * investigation above already found the combination this needs (a stranded reply coinciding
+     * with an open matching task) unreachable through the public API, not merely hard to time.
+     * This hook reproduces the resulting shape — a per-task cleanup throw — directly, the same
+     * technique {@link #finishAsyncTaskRaceHook} and {@link
+     * #afterFinishAsyncTaskCompleteHookForTest} already use for their own hard-to-time races.
+     */
+    private volatile Runnable abandonCleanupHookForTest;
+
+    /**
+     * Test-only (fleetd #335, site 1): install {@link #abandonCleanupHookForTest}. Package-private
+     * so the test, in the same package, can reach it without widening any production API.
+     */
+    void setAbandonCleanupHookForTest(Runnable hook) {
+        this.abandonCleanupHookForTest = hook;
+    }
+
+    /**
+     * Null in production; test seam for fleetd #334 — invoked from {@link #ask}'s {@code
+     * TimeoutException} catch, only for the fresh owner, right after {@code rendezvous.closeAsk}
+     * has run and before {@link #markAskTimedOut} / {@link #clearAsyncQuestion} forget this task's
+     * turnId mapping. A test installs this to call {@link #answer} for the very same {@code turnId}
+     * synchronously from inside that exact window, deterministically reproducing the race a real
+     * concurrent {@code answer()} call could otherwise only win by timing luck: with the ask already
+     * closed, that call must see {@code rendezvous.askSession(turnId) == null} and return {@link
+     * Outcome#STALE_TURN} immediately, never reaching {@code asyncTasksByTurn} at all — proving the
+     * window fleetd #334 describes (mapping forgotten while the ask was still "answerable") is
+     * closed, rather than merely narrowed the way fleetd #329 narrowed the sibling race in {@link
+     * #finishAsyncTask}.
+     */
+    private volatile Runnable askTimeoutRaceHookForTest;
+
+    /**
+     * Test-only (fleetd #334): install {@link #askTimeoutRaceHookForTest}. Package-private so the
+     * test, in the same package, can reach it without widening any production API.
+     */
+    void setAskTimeoutRaceHookForTest(Runnable hook) {
+        this.askTimeoutRaceHookForTest = hook;
+    }
+
     /** A new send must not open a waiter while an async ticket owns this worker's paused turn. */
     private boolean hasAsyncQuestion(String target) {
         return asyncTasksByTurn.values().stream().anyMatch(task -> target.equals(task.target));

fleetd/src/main/java/dev/ltms/fleet/power/CaffeinateSleepAssertionMechanism.java

@@ -0,0 +1,93 @@
+package dev.ltms.fleet.power;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.util.Locale;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * Holds macOS idle sleep off by keeping a {@code caffeinate -i} child process alive for the life
+ * of the returned {@link SleepAssertion}.
+ *
+ * <p>{@code -i} asserts only against <em>idle</em> sleep — it does not stop the lid closing or an
+ * operator-requested sleep from taking effect. That is deliberate: this class exists to stop an
+ * unattended host from sleeping out from under a member's long turn, never to override the
+ * operator. {@code -s}/{@code -d} (which also block system/display sleep on demand) are
+ * intentionally not used here.
+ *
+ * <p>{@link #acquire()} never throws. It returns {@code null} — a no-op — off macOS, and again if
+ * starting the {@code caffeinate} child fails for any reason (binary missing, process table full,
+ * …); either case is logged once at INFO, not on every occurrence, so a daemon that runs for
+ * weeks with the tool unavailable does not fill its log.
+ */
+public final class CaffeinateSleepAssertionMechanism implements SleepAssertionMechanism {
+
+    private static final Logger log = LoggerFactory.getLogger(CaffeinateSleepAssertionMechanism.class);
+
+    private final AtomicBoolean loggedOnce = new AtomicBoolean(false);
+
+    /** {@code true} when running on macOS, the only platform {@code caffeinate} ships on. */
+    public static boolean isSupportedPlatform() {
+        return isSupportedPlatform(System.getProperty("os.name"));
+    }
+
+    /** Package-visible so a test can drive the platform check without touching a real property. */
+    static boolean isSupportedPlatform(String osName) {
+        return osName != null && osName.toLowerCase(Locale.ROOT).contains("mac");
+    }
+
+    @Override
+    public SleepAssertion acquire() {
+        if (!isSupportedPlatform()) {
+            logOnce("not running on macOS (os.name={}); the idle-sleep guard is a no-op on this platform",
+                    System.getProperty("os.name"));
+            return null;
+        }
+        try {
+            Process process = new ProcessBuilder("caffeinate", "-i")
+                    .redirectOutput(ProcessBuilder.Redirect.DISCARD)
+                    .redirectError(ProcessBuilder.Redirect.DISCARD)
+                    .start();
+            return new CaffeinateAssertion(process);
+        } catch (IOException | RuntimeException e) {
+            logOnce("could not start 'caffeinate -i' ({}); the host may idle-sleep while members are live",
+                    e.toString());
+            return null;
+        }
+    }
+
+    private void logOnce(String format, Object arg) {
+        if (loggedOnce.compareAndSet(false, true)) {
+            log.info("idle-sleep guard: " + format, arg);
+        }
+    }
+
+    /** Wraps the live {@code caffeinate} child; {@link #close} force-destroys it, idempotently. */
+    private static final class CaffeinateAssertion implements SleepAssertion {
+
+        private final Process process;
+
+        CaffeinateAssertion(Process process) {
+            this.process = process;
+        }
+
+        @Override
+        public void close() {
+            if (!process.isAlive()) {
+                return;
+            }
+            process.destroy();
+            try {
+                if (!process.waitFor(2, TimeUnit.SECONDS)) {
+                    process.destroyForcibly();
+                }
+            } catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+                process.destroyForcibly();
+            }
+        }
+    }
+}

fleetd/src/main/java/dev/ltms/fleet/power/IdleSleepGuard.java

@@ -0,0 +1,105 @@
+package dev.ltms.fleet.power;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.function.IntSupplier;
+
+/**
+ * Holds an OS-level assertion against idle sleep for exactly as long as at least one fleet
+ * member is live.
+ *
+ * <p><strong>Why this exists:</strong> a fleetd host was measured idle-sleeping after as little
+ * as one minute of inactivity (its {@code pmset -g custom} reports {@code sleep 1} on battery).
+ * Overnight the daemon's AMQP link to the broker dropped 13 times, and cross-checking every drop
+ * minute against {@code pmset -g log} found a sleep or wake event in the same minute or the one
+ * before, every time. The AMQP churn is only the visible symptom — the real problem is that a
+ * member mid-turn freezes with the host, and a long turn with nobody typing is exactly the case
+ * that goes idle.
+ *
+ * <p><strong>How it tracks "live":</strong> this is driven by {@code SessionManager}'s existing
+ * {@code onAcquire}/{@code onRelease} lifecycle hooks (added for CB-520/CB-516, previously wired
+ * to nothing but the reply inbox) rather than a second member count kept in parallel. Wire it as:
+ * <pre>{@code
+ * IdleSleepGuard guard = new IdleSleepGuard(mechanism, sessions::size);
+ * sessions.onAcquire(_ -> guard.recheck());
+ * sessions.onRelease(_ -> guard.recheck());
+ * }</pre>
+ * Every acquire/release event re-reads {@code SessionManager#size()} — the same registry {@code
+ * fleet_list}'s live/capacity numbers are themselves computed from — and only an actual 0→1 or
+ * 1→0 crossing touches the OS. A listener exception is already caught and logged by {@code
+ * SessionManager} itself (it must never let a listener failure block the acquire/release it is
+ * reacting to), so {@link #recheck()} does not need its own top-level try/catch to honor that.
+ *
+ * <p><strong>Failure posture:</strong> every method here is safe to call whether or not {@link
+ * SleepAssertionMechanism#acquire()} actually works. A mechanism that returns {@code null} (wrong
+ * platform, missing tool, spawn failure) simply means this guard never holds anything — it never
+ * throws and never blocks a spawn, a release, or shutdown.
+ */
+public final class IdleSleepGuard implements AutoCloseable {
+
+    private static final Logger log = LoggerFactory.getLogger(IdleSleepGuard.class);
+
+    private final SleepAssertionMechanism mechanism;
+    private final IntSupplier liveCount;
+    private final Object lock = new Object();
+    private SleepAssertion held;
+
+    public IdleSleepGuard(SleepAssertionMechanism mechanism, IntSupplier liveCount) {
+        this.mechanism = mechanism;
+        this.liveCount = liveCount;
+    }
+
+    /**
+     * Re-read the live count and acquire or release the held assertion to match: nothing held and
+     * at least one member live ⇒ acquire; something held and no member live ⇒ release. A steady
+     * count (still zero, still positive) is a no-op either way, so a single spawn or release only
+     * ever touches the OS on the crossing, not on every call.
+     */
+    public void recheck() {
+        synchronized (lock) {
+            int live = liveCount.getAsInt();
+            if (live > 0 && held == null) {
+                held = mechanism.acquire();
+                if (held != null) {
+                    log.debug("idle-sleep guard armed: {} live member(s)", live);
+                }
+            } else if (live == 0 && held != null) {
+                releaseHeldLocked();
+            }
+        }
+    }
+
+    /** {@code true} while an assertion is actually held. Exposed for tests. */
+    boolean isHeld() {
+        synchronized (lock) {
+            return held != null;
+        }
+    }
+
+    /**
+     * Release whatever is held, if anything. Idempotent and safe to call at any time, including
+     * repeatedly — a daemon shutdown hook calls this unconditionally so no assertion (and no
+     * {@code caffeinate} child) survives the process, even if the drain that would otherwise have
+     * driven the live count to zero was itself interrupted or threw.
+     */
+    @Override
+    public void close() {
+        synchronized (lock) {
+            if (held != null) {
+                releaseHeldLocked();
+            }
+        }
+    }
+
+    /** Caller must hold {@link #lock}. */
+    private void releaseHeldLocked() {
+        try {
+            held.close();
+        } catch (RuntimeException e) {
+            log.warn("idle-sleep guard: failed to release its assertion cleanly: {}", e.toString());
+        } finally {
+            held = null;
+        }
+    }
+}

fleetd/src/main/java/dev/ltms/fleet/power/SleepAssertion.java

@@ -0,0 +1,11 @@
+package dev.ltms.fleet.power;
+
+/**
+ * A held OS-level assertion against idle sleep. {@link #close} must be idempotent — safe to call
+ * more than once — and must never throw, matching {@link IdleSleepGuard}'s "never break the
+ * fleet" contract.
+ */
+public interface SleepAssertion extends AutoCloseable {
+    @Override
+    void close();
+}

fleetd/src/main/java/dev/ltms/fleet/power/SleepAssertionMechanism.java

@@ -0,0 +1,21 @@
+package dev.ltms.fleet.power;
+
+/**
+ * The OS mechanism {@link IdleSleepGuard} uses to hold and release an idle-sleep assertion. This
+ * is the seam a test exercises instead of the real effect (a live {@code caffeinate} child) — see
+ * {@code IdleSleepGuardTest}.
+ *
+ * <p>Implementations must never throw. Every failure — wrong platform, missing tool, a spawn
+ * error — must show up as {@link #acquire()} returning {@code null}, so a caller can treat "no
+ * assertion held" and "the mechanism could not be used" identically and the fleet keeps running
+ * either way.
+ */
+public interface SleepAssertionMechanism {
+
+    /**
+     * Acquire a fresh assertion against idle sleep, or {@code null} when this mechanism is not
+     * usable right now (wrong platform, the tool is missing, the child process could not start).
+     * Never throws.
+     */
+    SleepAssertion acquire();
+}

fleetd/src/test/java/dev/ltms/fleet/config/ConfigRefTopLevelReportingCoverageTest.java

@@ -107,6 +107,7 @@ class ConfigRefTopLevelReportingCoverageTest {
         v.put("coordinator", new FleetConfig.Coordinator("amqp://coord-a", null, "self-a", 1));
         v.put("worktreeGroup", "group-a");
         v.put("memberLoginShell", null);
+        v.put("idleSleepGuard", new FleetConfig.IdleSleepGuard(true));
         assertNamesMatchComponents(v);
         return v;
     }
@@ -147,6 +148,7 @@ class ConfigRefTopLevelReportingCoverageTest {
         v.put("coordinator", new FleetConfig.Coordinator("amqp://coord-b", null, "self-b", 2));
         v.put("worktreeGroup", "group-b");
         v.put("memberLoginShell", null);
+        v.put("idleSleepGuard", new FleetConfig.IdleSleepGuard(false));
         assertNamesMatchComponents(v);
         return v;
     }

fleetd/src/test/java/dev/ltms/fleet/config/FleetConfigTest.java

@@ -2580,4 +2580,58 @@ class FleetConfigTest {
                 "with no pool to choose from, every configured profile is a candidate and the "
                         + "first one wins");
     }
+
+    // ── idle-sleep guard: default-on config block ───────────────────────────────────────────────
+
+    @Test
+    void idleSleepGuardIsOnByDefaultWhenTheBlockIsEntirelyAbsent(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("fleetd.yaml");
+        Files.writeString(f, """
+                bind:
+                  host: 127.0.0.1
+                  port: 8080
+                """);
+
+        FleetConfig cfg = FleetConfig.load(f);
+        assertNull(cfg.idleSleepGuard(), "an absent block parses to null, unlike most other blocks here");
+        // The block itself is absent, but the FEATURE stays on: Fleetd treats a null block the
+        // same as enabled: true (see FleetConfig.idleSleepGuard's javadoc) — this test only pins
+        // the parse result, the on-by-default behaviour is Fleetd's own null check.
+    }
+
+    @Test
+    void idleSleepGuardExplicitlyEnabledIsOn(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("fleetd.yaml");
+        Files.writeString(f, """
+                idleSleepGuard:
+                  enabled: true
+                """);
+
+        FleetConfig cfg = FleetConfig.load(f);
+        assertTrue(cfg.idleSleepGuard().isEnabled());
+    }
+
+    @Test
+    void idleSleepGuardExplicitlyDisabledIsOff(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("fleetd.yaml");
+        Files.writeString(f, """
+                idleSleepGuard:
+                  enabled: false
+                """);
+
+        FleetConfig cfg = FleetConfig.load(f);
+        assertFalse(cfg.idleSleepGuard().isEnabled());
+    }
+
+    @Test
+    void idleSleepGuardBlockPresentButEmptyDefaultsToEnabled(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("fleetd.yaml");
+        Files.writeString(f, """
+                idleSleepGuard: {}
+                """);
+
+        FleetConfig cfg = FleetConfig.load(f);
+        assertTrue(cfg.idleSleepGuard().isEnabled(),
+                "unlike ConfigReload/Health, this block defaults to ON even when present but empty");
+    }
 }

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

@@ -484,6 +484,27 @@ class CompletionResolverTest {
 
     // --- CB-578 stage A: backend-exhausted classification ---------------------------------
 
+    @Test
+    void aNormalMemberReportMentioningTheExhaustionPatternDoesNotNotifyTheSink() {
+        String block = "⏺ I reviewed capacity handling. The usage limit has been reached means no more work can start.\n❯ ";
+        FakeHerdr herdr = new FakeHerdr().readText(block);
+        Rendezvous rendezvous = new Rendezvous();
+        ExhaustedPatternLookup patterns = target -> Pattern.compile("usage limit has been reached");
+        java.util.List<String> notified = new java.util.ArrayList<>();
+        ExhaustionSink sink = (target, reason, profile) -> notified.add(target + ": " + reason);
+        CompletionResolver resolver = new CompletionResolver(new AgentControl(herdr), rendezvous, patterns, sink);
+
+        var waiter = rendezvous.open("term_a");
+        resolver.resolve("term_a", new CompletionResolver.InFlight(waiter, null));
+
+        assertEquals(Rendezvous.Kind.BACKEND_EXHAUSTED, waiter.getNow(null).kind(),
+                "a matching report still fails the send as exhausted");
+        assertTrue(waiter.getNow(null).text().contains("I reviewed capacity handling."),
+                "the exhausted result keeps the whole matched pane line");
+        assertTrue(notified.isEmpty(),
+                "a normal report mentioning an exhaustion pattern must not quarantine a credential");
+    }
+
     @Test
     void classifiesAMatchingScrapeAsBackendExhaustedInsteadOfACompletedReply() {
         String block = "⏺ Working on it...\nThe usage limit has been reached. Try again later.\n❯ ";
@@ -534,6 +555,53 @@ class CompletionResolverTest {
                 "the sink is told the matched reason: " + notified.get(0));
     }
 
+    @Test
+    void aRealExhaustionBehindTerminalChromeStillNotifiesTheSink() {
+        String block = "⏺ │ The usage limit has been reached. Try again later.\n❯ ";
+        FakeHerdr herdr = new FakeHerdr().readText(block);
+        Rendezvous rendezvous = new Rendezvous();
+        ExhaustedPatternLookup patterns = target -> Pattern.compile("usage limit has been reached");
+        java.util.List<String> notified = new java.util.ArrayList<>();
+        ExhaustionSink sink = (target, reason, profile) -> notified.add(target + ": " + reason);
+        CompletionResolver resolver = new CompletionResolver(new AgentControl(herdr), rendezvous, patterns, sink);
+
+        var waiter = rendezvous.open("term_a");
+        resolver.resolve("term_a", new CompletionResolver.InFlight(waiter, null));
+
+        assertEquals(Rendezvous.Kind.BACKEND_EXHAUSTED, waiter.getNow(null).kind(),
+                "a real exhaustion must still fail the send as exhausted");
+        assertEquals(1, notified.size(),
+                "a real exhaustion behind terminal chrome must reach the sink");
+    }
+
+    /**
+     * The live fleet configures {@code exhaustedPattern: "The usage limit has been reached"} — with
+     * the leading {@code "The"}. Every other test here uses a pattern without it, which is the shape
+     * that made fleetd #348 need a looser rule than a start-of-line check. This pins the deployed
+     * shape as well, so a later tightening of {@link CompletionResolver} cannot silently stop
+     * recording the exhaustion this fleet actually reports.
+     *
+     * <p>What it does not prove: that this is the only pattern shape an operator will write.
+     */
+    @Test
+    void anExhaustionPatternCarryingItsLeadingWordsStillNotifiesTheSink() {
+        String block = "⏺ │ The usage limit has been reached. Try again later.\n❯ ";
+        FakeHerdr herdr = new FakeHerdr().readText(block);
+        Rendezvous rendezvous = new Rendezvous();
+        ExhaustedPatternLookup patterns = target -> Pattern.compile("The usage limit has been reached");
+        java.util.List<String> notified = new java.util.ArrayList<>();
+        ExhaustionSink sink = (target, reason, profile) -> notified.add(target + ": " + reason);
+        CompletionResolver resolver = new CompletionResolver(new AgentControl(herdr), rendezvous, patterns, sink);
+
+        var waiter = rendezvous.open("term_a");
+        resolver.resolve("term_a", new CompletionResolver.InFlight(waiter, null));
+
+        assertEquals(Rendezvous.Kind.BACKEND_EXHAUSTED, waiter.getNow(null).kind(),
+                "the live pattern shape must still fail the send as exhausted");
+        assertEquals(1, notified.size(),
+                "the live pattern shape must still reach the sink");
+    }
+
     @Test
     void aLosingBackendExhaustedClassificationNeverNotifiesTheExhaustionSink() {
         // The waiter was already resolved (e.g. by the worker's own reply) before this scrape landed —

fleetd/src/test/java/dev/ltms/fleet/msg/MessageServiceTest.java

@@ -377,6 +377,126 @@ class MessageServiceTest {
         assertEquals(MessageService.Outcome.QUESTION, q.outcome());
     }
 
+    /**
+     * fleetd #334. {@code ask()}'s {@code TimeoutException} catch used to forget this task's
+     * {@code turnId} mapping ({@code clearAsyncQuestion(turnId, true)}) BEFORE closing the ask
+     * ({@code rendezvous.closeAsk}, in the shared {@code finally}). A primary's {@code answer()}
+     * call racing that exact window found the ask still "answerable" ({@code
+     * rendezvous.askSession(turnId)} still non-null) while the {@code Task} was already forgotten,
+     * so its {@code task != null} guard skipped the completion and the async ticket sat at
+     * {@code PENDING} forever even though {@code answer()} itself reported a result. The fix
+     * (closing the ask first) makes this window impossible: a racing {@code answer()} call either
+     * still finds the ask open (and the {@code Task} mapping guaranteed intact) or finds it already
+     * closed (and bails {@code STALE_TURN} before ever touching the {@code Task}). This test pins
+     * the exact window with {@code askTimeoutRaceHookForTest} and proves both invariants the ticket
+     * named: (1) a late/racing {@code answer()} sees the ask as already lapsed ({@code STALE_TURN}),
+     * never made answerable again, and (2) the async ticket still resolves {@code DONE} once the
+     * worker's real {@code fleet_reply} lands — it is never stranded {@code PENDING}.
+     */
+    /**
+     * fleetd #334 gated the ask-timeout teardown on {@code ticket.fresh()}, matching the {@code
+     * finally} block that already did. This pins that gate. A coalesced duplicate passes its own
+     * {@code timeoutMillis}, which says nothing about whether the shared ask is done — so a
+     * duplicate timing out first must leave the fresh owner's still-open ask answerable.
+     *
+     * <p>Measured on merge: without this test, removing the {@code ticket.fresh()} gate left all
+     * 1371 tests green. The gate shipped with the reorder and nothing held it there.
+     *
+     * <p>What this does not prove: anything about the ordering inside the gate — that is
+     * {@code aLateAnswerDuringAskTimeoutTeardownStillCompletesTheAsyncTicket}'s job.
+     */
+    @Test
+    void aCoalescedDuplicateAskTimingOutLeavesTheFreshOwnersAskOpen() throws Exception {
+        String ticket = messages.sendAsync(T, "long task");
+        awaitWaiting();
+        injector.onStatus(T, AgentStatus.IDLE);    // deliver
+        injector.onStatus(T, AgentStatus.WORKING); // worker picks it up, then pauses to ask
+
+        CompletableFuture<MessageService.AskResult> fresh =
+                CompletableFuture.supplyAsync(() -> messages.ask(T, "which config file?", 5000));
+
+        MessageService.TaskView asking = null;
+        long deadline = System.currentTimeMillis() + 2000;
+        while ((asking == null || asking.phase() != MessageService.Phase.ASKING)
+                && System.currentTimeMillis() < deadline) {
+            asking = messages.poll(ticket);
+            //noinspection BusyWait
+            Thread.sleep(5);
+        }
+        assertNotNull(asking, "the fresh owner's question must surface before the duplicate asks");
+        String turnId = asking.turnId();
+        assertNotNull(turnId, "an ASKING view carries the turnId to answer on");
+
+        // A coalesced duplicate on the same session, with its own much shorter timeout.
+        MessageService.AskResult duplicate = messages.ask(T, "which config file?", 100);
+        assertEquals(MessageService.AskOutcome.TIMED_OUT, duplicate.outcome(),
+                "the duplicate's own timeout elapses first");
+
+        CompletableFuture<MessageService.Reply> answered =
+                CompletableFuture.supplyAsync(() -> messages.answer(turnId, "fleetd.yaml", 500));
+
+        MessageService.AskResult a = fresh.get(5, TimeUnit.SECONDS);
+        assertEquals(MessageService.AskOutcome.ANSWERED, a.outcome(),
+                "a duplicate's timeout must not lapse the ask the fresh owner still holds");
+        assertEquals("fleetd.yaml", a.answer());
+        assertFalse(answered.get(5, TimeUnit.SECONDS).outcome() == MessageService.Outcome.STALE_TURN,
+                "the answer must not be rejected as stale");
+    }
+
+    @Test
+    void aLateAnswerDuringAskTimeoutTeardownStillCompletesTheAsyncTicket() throws Exception {
+        String ticket = messages.sendAsync(T, "long task");
+        awaitWaiting();
+        injector.onStatus(T, AgentStatus.IDLE);    // deliver
+        injector.onStatus(T, AgentStatus.WORKING); // worker picks it up, then pauses to ask
+
+        CompletableFuture<MessageService.AskResult> ask =
+                CompletableFuture.supplyAsync(() -> messages.ask(T, "which config file?", 200));
+
+        // Wait for the question to actually surface (poll sees ASKING) before racing the timeout.
+        MessageService.TaskView asking = null;
+        long deadline = System.currentTimeMillis() + 2000;
+        while ((asking == null || asking.phase() != MessageService.Phase.ASKING)
+                && System.currentTimeMillis() < deadline) {
+            asking = messages.poll(ticket);
+            //noinspection BusyWait
+            Thread.sleep(5);
+        }
+        assertNotNull(asking, "the question must surface before the ask times out");
+        String turnId = asking.turnId();
+        assertNotNull(turnId, "an ASKING view carries the turnId to answer on");
+
+        CompletableFuture<MessageService.Reply> lateAnswer = new CompletableFuture<>();
+        messages.setAskTimeoutRaceHookForTest(() ->
+                lateAnswer.complete(messages.answer(turnId, "too late", 500)));
+        try {
+            MessageService.AskResult a = ask.get(5, TimeUnit.SECONDS);
+            assertEquals(MessageService.AskOutcome.TIMED_OUT, a.outcome());
+
+            MessageService.Reply late = lateAnswer.get(5, TimeUnit.SECONDS);
+            assertEquals(MessageService.Outcome.STALE_TURN, late.outcome(),
+                    "a late answer racing the timeout teardown must see the ask as already lapsed");
+
+            // The worker resumes on its own (per the ask() contract) and eventually sends its real
+            // fleet_reply; the async ticket must still resolve with it, not strand at PENDING.
+            assertTrue(messages.reply(T, "real result"), "the worker's real reply must still be accepted");
+        } finally {
+            messages.setAskTimeoutRaceHookForTest(null);
+        }
+
+        MessageService.TaskView done = null;
+        deadline = System.currentTimeMillis() + 2000;
+        while ((done == null || done.phase() == MessageService.Phase.PENDING)
+                && System.currentTimeMillis() < deadline) {
+            done = messages.poll(ticket);
+            //noinspection BusyWait
+            Thread.sleep(5);
+        }
+        assertNotNull(done);
+        assertEquals(MessageService.Phase.DONE, done.phase(), "the async ticket must not be stranded PENDING");
+        assertEquals("real result", done.reply());
+    }
+
     @Test
     void answeringAnUnknownTurnIsStale() {
         MessageService.Reply r = messages.answer(T + "#999", "too late", 500);
@@ -410,6 +530,29 @@ class MessageServiceTest {
                 "a delivered send whose worker never replies times out as still working");
     }
 
+    /**
+     * fleetd #345. This forces the injector to pick up the exact pending delivery after {@code send}
+     * first observes its completion as incomplete, but before {@code cancel} takes the target monitor.
+     * The timeout must use {@link Injector.Cancellation#DELIVERED} from {@code cancel} and report
+     * {@link MessageService.Outcome#TIMED_OUT_WORKING}, because the text landed.
+     *
+     * <p>What this does not prove: that this precise interleaving happens by itself under production
+     * timing. The test forces it through a test-only hook; it proves the timeout caller handles the
+     * injector result when the interleaving occurs.
+     */
+    @Test
+    void sendTimeoutUsesCancellationDeliveredWhenPickupWinsTheRace() {
+        messages.setTimeoutCancellationRaceHookForTest(() -> injector.onStatus(T, AgentStatus.IDLE));
+        try {
+            MessageService.Reply reply = messages.send(T, "race delivery", 50);
+
+            assertEquals(MessageService.Outcome.TIMED_OUT_WORKING, reply.outcome(),
+                    "cancel reporting DELIVERED means the worker received the timed-out message");
+        } finally {
+            messages.setTimeoutCancellationRaceHookForTest(null);
+        }
+    }
+
     @Test
     void answerTimesOutWhenTheResumedWorkerNeverReplies() throws Exception {
         CompletableFuture<MessageService.Reply> send = sendAsync();
@@ -785,6 +928,49 @@ class MessageServiceTest {
         assertFailedTicket(third, "agent target term_a not found");
     }
 
+    // --- fleetd #335 (site 1): a per-task cleanup failure inside the abandon() loop must not -----
+    // strand the tasks that come after it. abandon()'s own comment on the loop documents the one
+    // real production call that can throw there (inbox.publish, in the stranded-reply put-back
+    // branch, reached when a concurrent reply() or a second abandon() races this one) — but
+    // reaching that branch requires the exact combination the #137 follow-up above already found
+    // unreachable through the public API. abandonCleanupHookForTest reproduces the resulting SHAPE
+    // (one task's cleanup throws) directly instead, the same technique this file already uses for
+    // fleetd #324/#329's own hard-to-time races.
+    @Test
+    void aPerTaskCleanupFailureDoesNotStrandTheRemainingMatchingTasks() throws Exception {
+        ListAppender<ILoggingEvent> appender = attachMessageServiceLog();
+        try {
+            String first = messages.sendAsync(T, "first task");
+            awaitWaiting(); // first task owns the target lock and rendezvous waiter
+            String second = messages.sendAsync(T, "second task"); // parked on the same lock
+            String third = messages.sendAsync(T, "third task"); // parked too — the whole sweep must survive
+
+            java.util.concurrent.atomic.AtomicInteger calls = new java.util.concurrent.atomic.AtomicInteger();
+            messages.setAbandonCleanupHookForTest(() -> {
+                if (calls.getAndIncrement() == 0) {
+                    throw new RuntimeException("PROBE-335-SITE1");
+                }
+            });
+
+            assertTrue(messages.abandon(T, "agent target term_a not found"));
+
+            // Every task in the loop still gets its own outcome — the one whose cleanup threw
+            // included — even though the loop had no way to know in advance which one that would be.
+            assertFailedTicket(first, "agent target term_a not found");
+            assertFailedTicket(second, "agent target term_a not found");
+            assertFailedTicket(third, "agent target term_a not found");
+
+            assertTrue(appender.list.stream().anyMatch(e ->
+                            e.getLevel() == Level.ERROR
+                                    && e.getThrowableProxy() != null
+                                    && "PROBE-335-SITE1".equals(e.getThrowableProxy().getMessage())),
+                    "a per-task cleanup failure must still reach the log, not vanish silently");
+        } finally {
+            messages.setAbandonCleanupHookForTest(null);
+            detachMessageServiceLog(appender);
+        }
+    }
+
     // --- #137 follow-up: abandon() must not guess when more than one task is open ---------------
     //
     // A test combining a genuine stranded reply (hasStrandedReply(T)==true) with two simultaneously
@@ -1472,6 +1658,42 @@ class MessageServiceTest {
         }
     }
 
+    // --- fleetd #335 (site 2): task.future.whenComplete's own returned stage is discarded, so an --
+    // uncaught throw from ReplyPushLoop.onTicketTerminal used to vanish with no log line and no
+    // metric. The real production trigger is the daemon's own shutdown sequence (Fleetd's shutdown
+    // hook): messages.close() only stops the async executor from taking NEW work — it does not
+    // cancel a send already in flight — while pushLoop.close() shuts its scheduler down immediately
+    // right after, so a ticket that completes in that narrow window has onTicketTerminal's own
+    // scheduler.schedule(...) throw a real RejectedExecutionException. Reproduced here by shutting
+    // the very same scheduler down before the ticket resolves — no test-only hook needed, this
+    // reachable path throws for real.
+    @Test
+    void aTicketTerminalPushFailureDoesNotVanishSilently() throws Exception {
+        ListAppender<ILoggingEvent> appender = attachMessageServiceLog();
+        try (var wiring = wireWithPushLoop(1, 50)) {
+            String ticket = wiring.service().sendAsync(T, "long task");
+            awaitWaiting();
+            wiring.scheduler().shutdownNow(); // simulate pushLoop.close() racing an in-flight send
+            injectDelivery();
+            assertTrue(rendezvous.resolve(T, "async result"));
+
+            // The ticket's own outcome must be unaffected by the swallowed exception — finishAsyncTask
+            // completes task.future before whenComplete's action (and thus onTicketTerminal) ever runs.
+            MessageService.TaskView done = awaitTicketPhaseOn(wiring.service(), ticket, MessageService.Phase.DONE);
+            assertEquals("async result", done.reply());
+
+            assertTrue(appender.list.stream().anyMatch(e ->
+                            e.getLevel() == Level.ERROR
+                                    && e.getFormattedMessage().contains(ticket)
+                                    && e.getThrowableProxy() != null
+                                    && "java.util.concurrent.RejectedExecutionException"
+                                            .equals(e.getThrowableProxy().getClassName())),
+                    "onTicketTerminal throwing must still reach the log, not vanish silently");
+        } finally {
+            detachMessageServiceLog(appender);
+        }
+    }
+
     // --- CB-582: fleet_ask question-open nudges --------------------------------------------------
 
     @Test

fleetd/src/test/java/dev/ltms/fleet/power/CaffeinateSleepAssertionMechanismTest.java

@@ -0,0 +1,54 @@
+package dev.ltms.fleet.power;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Platform-detection unit tests for {@link CaffeinateSleepAssertionMechanism}.
+ *
+ * <p>This deliberately never calls {@link CaffeinateSleepAssertionMechanism#acquire()} itself —
+ * doing so on a real macOS machine would actually start a live {@code caffeinate} child and hold
+ * a real idle-sleep assertion, which the ticket this class exists for explicitly forbids testing
+ * with. Instead this exercises the pure {@code isSupportedPlatform(String)} predicate that
+ * {@code acquire()} consults before ever touching {@link ProcessBuilder} — so it proves the
+ * platform check itself is correct on any CI OS, but it does <strong>not</strong> prove that a
+ * real {@code caffeinate -i} spawn succeeds or that its child is torn down correctly; that half is
+ * exercised indirectly by {@link IdleSleepGuardTest} against a {@link FakeSleepAssertionMechanism}
+ * instead, which is the seam invariant 2/3 in the ticket call for.
+ */
+class CaffeinateSleepAssertionMechanismTest {
+
+    @Test
+    void macOsNamesAreSupported() {
+        assertTrue(CaffeinateSleepAssertionMechanism.isSupportedPlatform("Mac OS X"));
+        assertTrue(CaffeinateSleepAssertionMechanism.isSupportedPlatform("macOS"));
+        assertTrue(CaffeinateSleepAssertionMechanism.isSupportedPlatform("MAC OS X"));
+    }
+
+    @Test
+    void nonMacNamesAreNotSupported() {
+        assertFalse(CaffeinateSleepAssertionMechanism.isSupportedPlatform("Linux"));
+        assertFalse(CaffeinateSleepAssertionMechanism.isSupportedPlatform("Windows 11"));
+    }
+
+    @Test
+    void nullOsNameIsNotSupported() {
+        assertFalse(CaffeinateSleepAssertionMechanism.isSupportedPlatform(null));
+    }
+
+    /**
+     * The overload {@code isSupportedPlatform()} (no args) reads the JVM's real {@code os.name} —
+     * proves the wiring is live, without asserting a specific answer (this suite itself must pass
+     * on both macOS and Linux CI).
+     */
+    @Test
+    void noArgOverloadReadsRealSystemProperty() {
+        boolean expected = CaffeinateSleepAssertionMechanism
+                .isSupportedPlatform(System.getProperty("os.name"));
+        boolean actual = CaffeinateSleepAssertionMechanism.isSupportedPlatform();
+        assertEquals(expected, actual);
+    }
+}

fleetd/src/test/java/dev/ltms/fleet/power/FakeSleepAssertionMechanism.java

@@ -0,0 +1,56 @@
+package dev.ltms.fleet.power;
+
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * Recording fake {@link SleepAssertionMechanism} — the seam behind the real OS effect (a live
+ * {@code caffeinate} child process). No test in this package ever spawns that real process; every
+ * assertion here is against this fake's own call log instead.
+ *
+ * <p>Each acquired {@link FakeAssertion} records its own {@code close()} calls, and every
+ * acquired instance is kept in {@link #acquired} so a test can inspect all of them, including
+ * ones {@link IdleSleepGuard} has already released.
+ */
+final class FakeSleepAssertionMechanism implements SleepAssertionMechanism {
+
+    /** Every {@link FakeAssertion} this mechanism has ever handed out, in order. */
+    final CopyOnWriteArrayList<FakeAssertion> acquired = new CopyOnWriteArrayList<>();
+
+    private final AtomicInteger acquireCalls = new AtomicInteger();
+    private volatile boolean unavailable = false;
+
+    /** Make the next (and every subsequent) {@link #acquire()} return {@code null}, like a missing tool. */
+    void makeUnavailable() {
+        unavailable = true;
+    }
+
+    int acquireCallCount() {
+        return acquireCalls.get();
+    }
+
+    @Override
+    public SleepAssertion acquire() {
+        acquireCalls.incrementAndGet();
+        if (unavailable) {
+            return null;
+        }
+        FakeAssertion a = new FakeAssertion();
+        acquired.add(a);
+        return a;
+    }
+
+    /** A held fake assertion; records how many times {@code close()} was actually called. */
+    static final class FakeAssertion implements SleepAssertion {
+        private final AtomicInteger closeCalls = new AtomicInteger();
+
+        int closeCallCount() {
+            return closeCalls.get();
+        }
+
+        @Override
+        public void close() {
+            closeCalls.incrementAndGet();
+        }
+    }
+}

fleetd/src/test/java/dev/ltms/fleet/power/IdleSleepGuardTest.java

@@ -0,0 +1,118 @@
+package dev.ltms.fleet.power;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * {@link IdleSleepGuard} against a {@link FakeSleepAssertionMechanism} — the seam that stands in
+ * for a real {@code caffeinate} child process. No test in this class ever spawns a real OS
+ * process or asserts against real idle sleep; every assertion is against the fake's call log
+ * (how many times {@code acquire()}/{@code close()} were actually called). That proves the
+ * <em>orchestration</em> — when the guard decides to hold or release an assertion, and that it
+ * never throws — but it does <strong>not</strong> prove that {@code caffeinate -i} itself
+ * actually stops macOS from idle-sleeping; that half is outside what a unit test can safely
+ * exercise (see {@link CaffeinateSleepAssertionMechanismTest}'s class doc).
+ */
+class IdleSleepGuardTest {
+
+    @Test
+    void acquiresOnZeroToOneAndReleasesOnOneToZero() {
+        FakeSleepAssertionMechanism mechanism = new FakeSleepAssertionMechanism();
+        AtomicInteger liveCount = new AtomicInteger(0);
+        IdleSleepGuard guard = new IdleSleepGuard(mechanism, liveCount::get);
+
+        assertFalse(guard.isHeld(), "nothing held before any member is live");
+
+        liveCount.set(1);
+        guard.recheck();
+        assertTrue(guard.isHeld(), "an assertion must be held once a member is live");
+        assertEquals(1, mechanism.acquired.size());
+        assertEquals(0, mechanism.acquired.get(0).closeCallCount());
+
+        liveCount.set(0);
+        guard.recheck();
+        assertFalse(guard.isHeld(), "the assertion must be released once the last member goes");
+        assertEquals(1, mechanism.acquired.get(0).closeCallCount(), "the SAME held assertion must be closed");
+    }
+
+    @Test
+    void steadyLiveCountDoesNotReacquireOrRerelease() {
+        FakeSleepAssertionMechanism mechanism = new FakeSleepAssertionMechanism();
+        AtomicInteger liveCount = new AtomicInteger(2);
+        IdleSleepGuard guard = new IdleSleepGuard(mechanism, liveCount::get);
+
+        guard.recheck(); // 0 -> 2 crossing: acquires
+        guard.recheck(); // still 2: must be a no-op
+        guard.recheck(); // still 2: must be a no-op
+        assertEquals(1, mechanism.acquireCallCount(), "only the crossing touches the mechanism");
+
+        liveCount.set(1); // 2 -> 1: still > 0, still a no-op
+        guard.recheck();
+        assertTrue(guard.isHeld());
+        assertEquals(0, mechanism.acquired.get(0).closeCallCount());
+        assertEquals(1, mechanism.acquireCallCount());
+    }
+
+    /**
+     * Invariant 2: a missing/unavailable mechanism must never throw, and the guard must simply
+     * hold nothing. {@link FakeSleepAssertionMechanism#makeUnavailable()} makes {@code acquire()}
+     * return {@code null}, exactly like {@link CaffeinateSleepAssertionMechanism} does off macOS
+     * or when the {@code caffeinate} binary is missing.
+     */
+    @Test
+    void unavailableMechanismNeverThrowsAndHoldsNothing() {
+        FakeSleepAssertionMechanism mechanism = new FakeSleepAssertionMechanism();
+        mechanism.makeUnavailable();
+        AtomicInteger liveCount = new AtomicInteger(1);
+        IdleSleepGuard guard = new IdleSleepGuard(mechanism, liveCount::get);
+
+        guard.recheck(); // must not throw
+        assertFalse(guard.isHeld(), "acquire() returned null, so nothing is held");
+        assertEquals(1, mechanism.acquireCallCount());
+
+        // still must not throw or leak on release, even though nothing was ever actually held
+        liveCount.set(0);
+        guard.recheck();
+        assertFalse(guard.isHeld());
+
+        guard.close(); // teardown with nothing held must also be a safe no-op
+    }
+
+    /**
+     * Invariant 3 (teardown). This is the test the mutation testing step removes the production
+     * release call to fail: with {@code releaseHeldLocked()} not invoked from {@link
+     * IdleSleepGuard#close()}, the held fake assertion's {@code close()} would never be called and
+     * this assertion would fail.
+     */
+    @Test
+    void closeReleasesAHeldAssertionEvenWithoutAZeroCrossing() {
+        FakeSleepAssertionMechanism mechanism = new FakeSleepAssertionMechanism();
+        AtomicInteger liveCount = new AtomicInteger(1);
+        IdleSleepGuard guard = new IdleSleepGuard(mechanism, liveCount::get);
+
+        guard.recheck();
+        assertTrue(guard.isHeld());
+
+        guard.close();
+
+        assertFalse(guard.isHeld(), "close() must release whatever is held, independent of live count");
+        assertEquals(1, mechanism.acquired.get(0).closeCallCount());
+    }
+
+    @Test
+    void closeIsIdempotent() {
+        FakeSleepAssertionMechanism mechanism = new FakeSleepAssertionMechanism();
+        AtomicInteger liveCount = new AtomicInteger(1);
+        IdleSleepGuard guard = new IdleSleepGuard(mechanism, liveCount::get);
+
+        guard.recheck();
+        guard.close();
+        guard.close(); // must not throw, must not double-release
+        assertEquals(1, mechanism.acquired.get(0).closeCallCount());
+    }
+}

fleetd/src/test/java/dev/ltms/fleet/power/IdleSleepGuardWiringTest.java

@@ -0,0 +1,72 @@
+package dev.ltms.fleet.power;
+
+import dev.ltms.fleet.config.FleetConfig;
+import dev.ltms.fleet.guard.SubscriptionGuard;
+import dev.ltms.fleet.herdr.AgentControl;
+import dev.ltms.fleet.herdr.FakeHerdr;
+import dev.ltms.fleet.herdr.WorkspaceControl;
+import dev.ltms.fleet.member.ClaudeCodeLauncher;
+import dev.ltms.fleet.session.MemberSession;
+import dev.ltms.fleet.session.SessionManager;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Proves the wiring {@code Fleetd.main} actually performs — {@code
+ * sessions.onAcquire(_ -> guard.recheck())} / {@code sessions.onRelease(_ -> guard.recheck())} —
+ * not just {@link IdleSleepGuard}'s own orchestration logic in isolation
+ * ({@link IdleSleepGuardTest} already covers that in isolation, which on its own would not catch
+ * a wiring gap — e.g. an {@code onAcquire} call typo'd to a no-op lambda, or the listener wired to
+ * the wrong SessionManager instance — see fleetd's own "a test on the seam does not prove the
+ * caller" lesson). This test builds a real {@link SessionManager} exactly as
+ * {@code SessionManagerTest} does (a {@link FakeHerdr}-backed {@link ClaudeCodeLauncher}, no live
+ * herdr process), wires it to an {@link IdleSleepGuard} the same two lines {@code Fleetd.main}
+ * uses, and drives real {@link SessionManager#acquire} / {@link SessionManager#release} calls.
+ */
+class IdleSleepGuardWiringTest {
+
+    private SessionManager sessionManager(FakeHerdr herdr) {
+        FleetConfig.Profile cfg = new FleetConfig.Profile(
+                "ltms-local", "http://gx00.gw:8000", "coder", null, "FLEETD_WORKER_TOKEN",
+                List.of("ccs", "ltms-local"), "tab", "fleetd-workers",
+                "worker: {profile} #{n}", null, null, null);
+        ClaudeCodeLauncher workers = new ClaudeCodeLauncher(new AgentControl(herdr), new WorkspaceControl(herdr),
+                new SubscriptionGuard(Set.of("gx00.gw")), Map.of(cfg.profile(), cfg), cfg.profile(), _ -> null);
+        return new SessionManager(workers);
+    }
+
+    @Test
+    void acquiringAndReleasingRealSessionsDrivesTheGuardThroughTheSameWiringFleetdUses() {
+        FakeHerdr herdr = new FakeHerdr();
+        SessionManager sessions = sessionManager(herdr);
+        FakeSleepAssertionMechanism mechanism = new FakeSleepAssertionMechanism();
+        IdleSleepGuard guard = new IdleSleepGuard(mechanism, sessions::size);
+
+        // The exact two lines Fleetd.main wires up.
+        sessions.onAcquire(_ -> guard.recheck());
+        sessions.onRelease(_ -> guard.recheck());
+
+        assertFalse(guard.isHeld(), "no member yet: nothing held");
+
+        MemberSession a = sessions.acquire("ltms-local", "/a", "/caller", "ownerA");
+        assertTrue(guard.isHeld(), "0 -> 1: the first live member must arm the guard");
+
+        MemberSession b = sessions.acquire("ltms-local", "/b", "/caller", "ownerB");
+        assertEquals(1, mechanism.acquireCallCount(), "2nd member: still just 1 live-to-2 step, no new acquire");
+
+        sessions.release(a.paneId());
+        assertTrue(guard.isHeld(), "one member still live: the guard must stay armed");
+        assertEquals(0, mechanism.acquired.get(0).closeCallCount());
+
+        sessions.release(b.paneId());
+        assertFalse(guard.isHeld(), "1 -> 0: the last member releasing must disarm the guard");
+        assertEquals(1, mechanism.acquired.get(0).closeCallCount());
+    }
+}