fleetd #284: free failed-session capacity

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

@@ -858,14 +858,15 @@ public final class Fleetd {
     }
 
     /**
-     * Count sessions that occupy a profile's spawn capacity. A {@code BACKEND_ERROR} session stays
-     * in the roster so {@code fleet_list} can show its failure, but its dead backend cannot use a
-     * seat or accept another delivery.
+     * Count sessions that occupy a profile's spawn capacity. A {@code BACKEND_ERROR} or
+     * {@code FAILED} session stays in the roster so {@code fleet_list} can show its failure, but a
+     * member that cannot accept another delivery does not use a seat.
      */
     static int liveSessionCount(List<MemberSession> roster, String profileName) {
         return (int) roster.stream()
                 .filter(session -> profileName.equals(session.profile()))
                 .filter(session -> session.state() != MemberSession.State.BACKEND_ERROR)
+                .filter(session -> session.state() != MemberSession.State.FAILED)
                 .count();
     }
 

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

@@ -322,8 +322,9 @@ public record FleetConfig(
      *                       statement that does not stop being true just because the profile was
      *                       named directly. A negative value has no sane meaning (there is no
      *                       "excluded" to degrade to below zero) and is refused at config load
-     *                       instead, naming the profile and the key. Live means any session the
-     *                       registry still owns (acquired and not yet released), in any state.
+     *                       instead, naming the profile and the key. Live means a session that can
+     *                       receive another delivery. The roster keeps terminal {@code BACKEND_ERROR}
+     *                       and {@code FAILED} sessions for diagnostics, but they do not use capacity.
      * @param kind           which peer launcher spawns this profile: {@code "claude-code"} (default —
      *                       the {@link dev.ltms.fleet.member.ClaudeCodeLauncher}) or {@code "opencode"}.
      *                       The {@code CompositePeerLauncher} routes {@code spawn}/reap by this value, so

fleetd/src/main/java/dev/ltms/fleet/mcp/FleetMcp.java

@@ -1196,7 +1196,7 @@ public final class FleetMcp {
         int leadSeatCount = leadSeats.seatsFor().apply(profile);
         int reclaimable = (int) roster.stream().filter(s -> profile.equals(s.profile()))
                 .filter(s -> s.state() == MemberSession.State.READY || s.state() == MemberSession.State.DONE
-                        || s.state() == MemberSession.State.BACKEND_ERROR)
+                        || s.state() == MemberSession.State.BACKEND_ERROR || s.state() == MemberSession.State.FAILED)
                 .filter(s -> messages == null || (!messages.hasAcceptedDelivery(s.terminalId()) && !messages.hasInboxMessage(s.terminalId())))
                 .count();
         Map<String, Object> row = new LinkedHashMap<>();

fleetd/src/test/java/dev/ltms/fleet/FleetdBackendErrorSinkTest.java

@@ -230,6 +230,28 @@ class FleetdBackendErrorSinkTest {
     @Test
     @DisplayName("a backend-error session no longer blocks the real maxLoad spawn gate")
     void backendErrorSessionDoesNotBlockFreshSpawnAtMaxLoad() {
+        SessionManager sessions = capacityLimitedSessions();
+        MemberSession failed = sessions.acquire("terra", null, null, null);
+
+        assertTrue(sessions.onBackendError(failed.terminalId(), "backend exited"));
+
+        MemberSession fresh = sessions.acquire("terra", null, null, null);
+        assertEquals("terra", fresh.profile(), "the real maxLoad gate grants a fresh spawn after a backend error");
+    }
+
+    @Test
+    @DisplayName("a failed session no longer blocks the real maxLoad spawn gate")
+    void failedSessionDoesNotBlockFreshSpawnAtMaxLoad() {
+        SessionManager sessions = capacityLimitedSessions();
+        MemberSession failed = sessions.acquire("terra", null, null, null);
+
+        sessions.onTurnFailed(failed.terminalId());
+
+        MemberSession fresh = sessions.acquire("terra", null, null, null);
+        assertEquals("terra", fresh.profile(), "the real maxLoad gate grants a fresh spawn after a failed turn");
+    }
+
+    private static SessionManager capacityLimitedSessions() {
         FakeHerdr herdr = new FakeHerdr();
         FleetConfig.Profile profile = new FleetConfig.Profile("terra", "http://gx00.gw:8000", "coder",
                 null, "FLEETD_WORKER_TOKEN", List.of("claude"), "tab", "fleetd-workers",
@@ -242,11 +264,6 @@ class FleetdBackendErrorSinkTest {
                 PlacementPolicies.fixed(), name -> Fleetd.liveSessionCount(sessionsRef.get().roster(), name));
         SessionManager sessions = new SessionManager(workers);
         sessionsRef.set(sessions);
-        MemberSession failed = sessions.acquire("terra", null, null, null);
-
-        assertTrue(sessions.onBackendError(failed.terminalId(), "backend exited"));
-
-        MemberSession fresh = sessions.acquire("terra", null, null, null);
-        assertEquals("terra", fresh.profile(), "the real maxLoad gate grants a fresh spawn after a backend error");
+        return sessions;
     }
 }

fleetd/src/test/java/dev/ltms/fleet/mcp/FleetMcpTest.java

@@ -605,18 +605,20 @@ class FleetMcpTest {
     }
 
     @Test
-    void capacityReportsABackendErrorSessionAsReclaimable() {
+    void capacityReportsTerminalFailureSessionsAsReclaimable() {
         FakeHerdr h = new FakeHerdr();
         SessionManager sessions = new SessionManager(workerService(h, "http://gx00.gw:8000", Set.of("gx00.gw")));
-        MemberSession session = sessions.acquire("ltms-local", null, null, null);
-        assertTrue(sessions.onBackendError(session.terminalId(), "backend exited"));
+        MemberSession backendError = sessions.acquire("ltms-local", null, null, null);
+        MemberSession failed = sessions.acquire("ltms-local", null, null, null);
+        assertTrue(sessions.onBackendError(backendError.terminalId(), "backend exited"));
+        sessions.onTurnFailed(failed.terminalId());
 
         String out = textOf(FleetMcp.listFleet(workerService(h, "http://gx00.gw:8000", Set.of("gx00.gw")),
                 sessions, null, new FleetMcp.CapacitySource(profile -> 0, profile -> 1,
                 () -> Set.of("ltms-local"), () -> 0), new FleetMcp.HealthCoverageSource(() -> "off"),
                 FleetMcp.QuarantineSource.none(), Map.of(), ""));
 
-        assertTrue(out.contains("\"reclaimable\":1"), out);
+        assertTrue(out.contains("\"reclaimable\":2"), out);
     }
 
     @Test