diff --git a/fleetd/src/main/java/dev/ltms/fleet/mcp/FleetMcp.java b/fleetd/src/main/java/dev/ltms/fleet/mcp/FleetMcp.java
index 6685105..16e19a8 100644
--- a/fleetd/src/main/java/dev/ltms/fleet/mcp/FleetMcp.java
+++ b/fleetd/src/main/java/dev/ltms/fleet/mcp/FleetMcp.java
@@ -1397,11 +1397,11 @@ public final class FleetMcp {
      * {@code mailbox.pending} counts only broker-<em>ready</em> messages; a held message is already
      * an unacked delivery sitting with this consumer, so the normal, healthy state of a blocked lead
      * is {@code "pending": 0} next to a non-empty {@code held[]} — which invites the false reading
-     * "these are only in memory, a restart will lose them". They are not: {@code LeadMailbox}
-     * consumes with manual ack, so held mail is a durable broker delivery. {@code heldCount} is the
-     * honest second number beside {@code pending} ({@code held.size()}, not left for the reader to
-     * count the array), and {@code heldDurable} states the fact in words rather than leaving
-     * {@code pending} as the only number next to {@code held[]}.
+     * "these are only in memory, a restart will lose them". {@code heldCount} is the honest second
+     * number beside {@code pending} ({@code held.size()}, not left for the reader to count the
+     * array). {@code heldDurable} comes straight from {@link LeadChannel#heldDurable}, which the
+     * channel implementation derives from what it actually did when it declared and consumed its own
+     * queue (fleetd #440) — this method never asserts the fact itself.
      */
     private static Map<String, Object> coordinatorView(CoordinationSource coordination) {
         LeadChannel channel = coordination.leadChannel();
@@ -1415,7 +1415,7 @@ public final class FleetMcp {
         row.put("configured", true);
         row.put("mailbox", mailboxView(probe(channel, selfId)));
         row.put("heldCount", held.size());
-        row.put("heldDurable", true);
+        row.put("heldDurable", channel.heldDurable());
         row.put("held", held.stream().map(FleetMcp::heldView).toList());
         row.put("peers", coordination.peers().stream().map(p -> peerView(channel, p)).toList());
         return row;
diff --git a/fleetd/src/main/java/dev/ltms/fleet/msg/LeadChannel.java b/fleetd/src/main/java/dev/ltms/fleet/msg/LeadChannel.java
index d7c8931..653aa44 100644
--- a/fleetd/src/main/java/dev/ltms/fleet/msg/LeadChannel.java
+++ b/fleetd/src/main/java/dev/ltms/fleet/msg/LeadChannel.java
@@ -42,6 +42,18 @@ public interface LeadChannel {
     /** This daemon's own lead coordination id — the mailbox it owns, and the {@code from} it sends as. */
     String selfCoordId();
 
+    /**
+     * Whether a message sitting in {@link #peek}'s held set (fetched but not yet {@link #ack}ed) is
+     * still safe if this daemon crashes or restarts right now — the conclusion of two independent
+     * facts about how this channel owns its own queue: the queue was declared <em>durable</em>, and
+     * the consumer that filled {@code held} uses <em>manual ack</em>, so an unacked delivery is still
+     * owned by the broker rather than only in this process's memory. Both must hold for {@code true};
+     * an implementation must derive this from what it actually did when it declared and consumed its
+     * queue, never return a literal — fleetd #440 found {@code FleetMcp}'s {@code heldDurable} field
+     * doing exactly that, unable to ever report {@code false} even after the fact stopped being true.
+     */
+    boolean heldDurable();
+
     /**
      * A non-destructive look at {@code coordId}'s mailbox — does it exist, how many messages are
      * waiting on it, and how many consumers are attached — without owning, consuming, or otherwise
diff --git a/fleetd/src/main/java/dev/ltms/fleet/msg/LeadMailbox.java b/fleetd/src/main/java/dev/ltms/fleet/msg/LeadMailbox.java
index a9283f1..e57a6ad 100644
--- a/fleetd/src/main/java/dev/ltms/fleet/msg/LeadMailbox.java
+++ b/fleetd/src/main/java/dev/ltms/fleet/msg/LeadMailbox.java
@@ -86,6 +86,12 @@ public final class LeadMailbox implements LeadChannel, AutoCloseable {
     private final Object channelLock = new Object();
     /** msgId → held delivery, for this mailbox's own queue only (there is exactly one). */
     private final LinkedHashMap<String, Held> held = new LinkedHashMap<>();
+    /**
+     * fleetd #440: the answer to {@link #heldDurable()}, set once by {@link #own()} from the exact
+     * booleans it passed to {@code queueDeclare}/{@code basicConsume} — never a separate literal that
+     * could drift from what those calls actually did.
+     */
+    private boolean heldDurable;
     /** Successful broker acks on this connection, retained only to make a repeated caller ack quiet. */
     private final LinkedHashMap<String, Boolean> recentlyAcked = new LinkedHashMap<>();
     /** Bounds {@link #recentlyAcked}: it is only an idempotency aid, never delivery state. */
@@ -191,13 +197,22 @@ public final class LeadMailbox implements LeadChannel, AutoCloseable {
     /** Declare + consume this daemon's own {@code lead.<selfCoordId>.inbox}. Called once, at construction. */
     private void own() throws IOException {
         String queue = queueName(selfCoordId);
+        boolean durableQueue = true; // durable, non-exclusive, keep on idle
+        boolean autoAck = false; // manual ack
         synchronized (channelLock) {
-            channel.queueDeclare(queue, true, false, false, null); // durable, non-exclusive, keep on idle
-            channel.basicConsume(queue, false, deliverCallback(), _ -> { }); // autoAck=false: manual ack
+            channel.queueDeclare(queue, durableQueue, false, false, null);
+            channel.basicConsume(queue, autoAck, deliverCallback(), _ -> { });
         }
+        // fleetd #440: held mail is durable only while both hold — a durable queue AND manual ack.
+        this.heldDurable = durableQueue && !autoAck;
         log.debug("lead mailbox owns queue {} for coord-id {}", queue, selfCoordId);
     }
 
+    @Override
+    public boolean heldDurable() {
+        return heldDurable;
+    }
+
     /**
      * Publish {@code msg} to {@code toCoordId}'s mailbox and block until the broker's publisher
      * confirm for it lands. Does <em>not</em> imply owning or consuming {@code toCoordId}'s queue.
diff --git a/fleetd/src/test/java/dev/ltms/fleet/mcp/FleetMcpTest.java b/fleetd/src/test/java/dev/ltms/fleet/mcp/FleetMcpTest.java
index e55bdbd..2186371 100644
--- a/fleetd/src/test/java/dev/ltms/fleet/mcp/FleetMcpTest.java
+++ b/fleetd/src/test/java/dev/ltms/fleet/mcp/FleetMcpTest.java
@@ -734,6 +734,32 @@ class FleetMcpTest {
                 "must state the durability fact, not leave pending as the only number next to held[]: " + out);
     }
 
+    /**
+     * fleetd #440: {@code heldDurable} must be a derived fact, not a literal — so it can report
+     * {@code false} when the channel behind it says held mail is not durable (a non-durable queue,
+     * or a consumer running with {@code autoAck=true}). A test that only ever asserts {@code true}
+     * repeats the defect this ticket fixes.
+     */
+    @Test
+    void listReportsHeldDurableFalseWhenTheChannelSaysMailIsNotDurable() {
+        FakeHerdr h = new FakeHerdr();
+        SessionManager sessions = new SessionManager(workerService(h, "http://gx00.gw:8000", Set.of("gx00.gw")));
+        FakeLeadChannel channel = new FakeLeadChannel("mac-opus")
+                .withMailbox("mac-opus", LeadChannel.MailboxState.exists("mac-opus", 0, 1))
+                .withHeldDurable(false)
+                .hold(new LeadMessage("m1", "fleet01-lead", "mac-opus", "one"));
+
+        McpSchema.CallToolResult res = FleetMcp.listFleet(
+                workerService(h, "http://gx00.gw:8000", Set.of("gx00.gw")), sessions, null,
+                FleetMcp.CapacitySource.none(), new FleetMcp.HealthCoverageSource(() -> "off"),
+                FleetMcp.QuarantineSource.none(), Map.of(), "",
+                new FleetMcp.CoordinationSource(channel, List.of()));
+
+        String out = textOf(res);
+        assertTrue(out.contains("\"heldDurable\":false"),
+                "heldDurable must follow the channel, not a hardcoded true: " + out);
+    }
+
     // ── fleetd #421: a lead reads (never consumes) its own held peer mail ──────────────────────
 
     @Test
@@ -834,6 +860,9 @@ class FleetMcpTest {
             @Override
             public String selfCoordId() { return "mac-opus"; }
 
+            @Override
+            public boolean heldDurable() { return true; }
+
             @Override
             public MailboxState inspect(String coordId) {
                 started.countDown();
diff --git a/fleetd/src/test/java/dev/ltms/fleet/msg/FakeLeadChannel.java b/fleetd/src/test/java/dev/ltms/fleet/msg/FakeLeadChannel.java
index b603a79..f631483 100644
--- a/fleetd/src/test/java/dev/ltms/fleet/msg/FakeLeadChannel.java
+++ b/fleetd/src/test/java/dev/ltms/fleet/msg/FakeLeadChannel.java
@@ -28,11 +28,19 @@ public final class FakeLeadChannel implements LeadChannel {
     private volatile IllegalStateException publishFailure;
     /** Canned {@link #inspect} results by coord-id — absent for any coord-id not configured here. */
     private final Map<String, MailboxState> mailboxes = new ConcurrentHashMap<>();
+    /** fleetd #440: matches {@link LeadMailbox}'s real default (durable queue + manual ack) unless overridden. */
+    private volatile boolean heldDurable = true;
 
     public FakeLeadChannel(String selfCoordId) {
         this.selfCoordId = selfCoordId;
     }
 
+    /** Make {@link #heldDurable()} report {@code durable} — the fleetd #440 seam for the false case. */
+    public FakeLeadChannel withHeldDurable(boolean durable) {
+        this.heldDurable = durable;
+        return this;
+    }
+
     /** Make {@link #inspect(String)} return {@code state} for {@code coordId} instead of "absent". */
     public FakeLeadChannel withMailbox(String coordId, MailboxState state) {
         mailboxes.put(coordId, state);
@@ -80,6 +88,11 @@ public final class FakeLeadChannel implements LeadChannel {
         return mailboxes.getOrDefault(coordId, MailboxState.absent(coordId));
     }
 
+    @Override
+    public boolean heldDurable() {
+        return heldDurable;
+    }
+
     public List<LeadMessage> published() {
         return List.copyOf(published);
     }
diff --git a/fleetd/src/test/java/dev/ltms/fleet/msg/LeadMailboxTest.java b/fleetd/src/test/java/dev/ltms/fleet/msg/LeadMailboxTest.java
index 6998b47..e0c36ae 100644
--- a/fleetd/src/test/java/dev/ltms/fleet/msg/LeadMailboxTest.java
+++ b/fleetd/src/test/java/dev/ltms/fleet/msg/LeadMailboxTest.java
@@ -207,6 +207,21 @@ class LeadMailboxTest {
         }
     }
 
+    /**
+     * fleetd #440: {@code heldDurable()} must be derived from what {@link LeadMailbox#own} actually
+     * did against the real broker — a durable queue declare plus a manual-ack consumer — not a
+     * hardcoded literal. This is the mutation-sensitive test: flip {@code own()}'s {@code autoAck}
+     * local to {@code true} (or its {@code durableQueue} local to {@code false}) and this must fail.
+     */
+    @Test
+    void heldDurableReportsTrueBecauseTheQueueIsDurableAndTheConsumeIsManualAck() throws Exception {
+        String self = coordId("lead-held-durable");
+        try (LeadMailbox mailbox = LeadMailbox.open(uri(), self)) {
+            assertTrue(mailbox.heldDurable(),
+                    "own() declares a durable queue and consumes with autoAck=false, so held mail is durable");
+        }
+    }
+
     @Test
     void inspectReportsAMissingMailboxAsAbsentRatherThanThrowing() throws Exception {
         String nobody = coordId("lead-inspect-nobody");