CB-113: reliable worker readiness gate + submission nudge

Delegating right after spawn failed: herdr reports 'idle' during the worker's
boot, so the injector delivered into a not-ready TUI (paste lost) and wedged the
worker. Two fixes:

- Readiness gate: a worker is 'available' only once its Claude connects the bridge
  MCP (the daemon observes it via peer-PID->terminal). WorkerPresence tracks it; the
  injector holds the first delivery until present, so it never pastes into the boot
  window. Exposed as 'ready' on GET /sessions/{id}/status.
- Submission nudge: the Enter accompanying a delivery can race the paste (esp. right
  as the TUI becomes ready), leaving text unsubmitted. While a delivered message
  stays idle (not picked up), the injector re-sends Enter each poll until the worker
  starts (WORKING) or the grace expires.

Validated live: spawn + immediate delegate now holds during boot (ready=false),
delivers on MCP-connect, re-nudges Enter, worker replies. 102 tests green.

bridged/src/test/java/dev/ltms/bridged/inject/InjectorTest.java

@@ -51,6 +51,47 @@ class InjectorTest {
         assertEquals(List.of("hello"), sent());
     }
 
+    @Test
+    void holdsDeliveryUntilTheWorkerIsAvailable() {
+        // CB-113: idle alone is not enough — hold until the worker's MCP is connected (ready).
+        java.util.Set<String> ready = new java.util.HashSet<>();
+        Injector inj = new Injector(new AgentControl(herdr), TurnListener.NOOP, ready::contains);
+        inj.enqueue(T, "task");
+
+        inj.onStatus(T, AgentStatus.IDLE); // idle but not yet available → held out of the boot window
+        assertEquals(List.of(), sent(), "must not deliver into a not-yet-available worker");
+
+        ready.add(T);                      // the worker's Claude connects the bridge MCP
+        inj.onStatus(T, AgentStatus.IDLE);
+        assertEquals(List.of("task"), sent(), "delivers once the worker is available");
+    }
+
+    @SuppressWarnings("unchecked")
+    private long enterKeystrokes() {
+        return herdr.calls.stream()
+                .filter(c -> c.method().equals("agent.send"))
+                .filter(c -> "\r".equals(((Map<String, Object>) c.params()).get("text")))
+                .count();
+    }
+
+    @Test
+    void resubmitsEnterWhenADeliveredMessageIsNotPickedUp() {
+        // CB-113: the Enter at delivery can race the paste; while the worker stays idle (not picked
+        // up), the injector re-nudges Enter so the pending paste submits.
+        injector.enqueue(T, "task");
+        injector.onStatus(T, AgentStatus.IDLE); // deliver: paste + one Enter
+        long afterDeliver = enterKeystrokes();
+
+        injector.onStatus(T, AgentStatus.IDLE); // still idle → re-nudge Enter
+        injector.onStatus(T, AgentStatus.IDLE); // and again
+        assertTrue(enterKeystrokes() > afterDeliver, "an unpicked-up delivery re-nudges Enter");
+
+        injector.onStatus(T, AgentStatus.WORKING); // worker finally starts
+        long atPickup = enterKeystrokes();
+        injector.onStatus(T, AgentStatus.WORKING);
+        assertEquals(atPickup, enterKeystrokes(), "no more nudges once the worker has picked up");
+    }
+
     @Test
     void holdsWhileWorkingThenDeliversOnIdle() {
         injector.enqueue(T, "later");

bridged/src/test/java/dev/ltms/bridged/inject/WorkerPresenceTest.java

@@ -0,0 +1,33 @@
+package dev.ltms.bridged.inject;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/** The CB-113 worker-availability registry. */
+class WorkerPresenceTest {
+
+    @Test
+    void tracksPresenceAndForgets() {
+        WorkerPresence p = new WorkerPresence();
+        assertFalse(p.isPresent("term_a"), "unseen worker is not available");
+
+        p.markPresent("term_a");
+        assertTrue(p.isPresent("term_a"), "a worker seen on the MCP is available");
+
+        p.forget("term_a");
+        assertFalse(p.isPresent("term_a"), "a torn-down worker is no longer available");
+    }
+
+    @Test
+    void nullOrBlankMarkIsANoOp() {
+        WorkerPresence p = new WorkerPresence();
+        assertDoesNotThrow(() -> {
+            p.markPresent(null);
+            p.markPresent("  ");
+        });
+        assertFalse(p.isPresent(""), "blank/null contacts (the primary) are never present");
+    }
+}

bridged/src/test/java/dev/ltms/bridged/rest/BridgedAppTest.java

@@ -9,6 +9,7 @@ import dev.ltms.bridged.herdr.FakeHerdr;
 import dev.ltms.bridged.herdr.WorkspaceControl;
 import dev.ltms.bridged.inject.Injector;
 import dev.ltms.bridged.inject.StatusPoller;
+import dev.ltms.bridged.inject.WorkerPresence;
 import dev.ltms.bridged.msg.MessageService;
 import dev.ltms.bridged.msg.Rendezvous;
 import dev.ltms.bridged.worker.WorkerService;
@@ -36,6 +37,7 @@ class BridgedAppTest {
 
     private final ObjectMapper mapper = new ObjectMapper();
     private final HttpClient http = HttpClient.newHttpClient();
+    private final WorkerPresence presence = new WorkerPresence();
     private Javalin app;
     private StatusPoller poller;
 
@@ -63,7 +65,8 @@ class BridgedAppTest {
         poller.start();
         Rendezvous rendezvous = new Rendezvous();
         MessageService messages = new MessageService(agents, injector, rendezvous);
-        app = new BridgedApp(herdr, workers, messages, rendezvous, null).build().start("127.0.0.1", 0);
+        app = new BridgedApp(herdr, workers, messages, rendezvous, this.presence, null)
+                .build().start("127.0.0.1", 0);
         return app.port();
     }
 
@@ -380,6 +383,16 @@ class BridgedAppTest {
         assertEquals("blocked", mapper.readTree(res.body()).get("status").asText());
     }
 
+    @Test
+    void sessionStatusReportsReadinessFromMcpPresence() throws Exception {
+        int port = start(new FakeHerdr(), "http://gx00.gw:8000", Set.of("gx00.gw"));
+        // Not yet seen on the bridge MCP → not ready.
+        assertFalse(mapper.readTree(req(port, "GET", "/sessions/term_a/status").body()).get("ready").asBoolean());
+        // Worker connects its MCP client → available.
+        presence.markPresent("term_a");
+        assertTrue(mapper.readTree(req(port, "GET", "/sessions/term_a/status").body()).get("ready").asBoolean());
+    }
+
     @Test
     void stopWorkerInPanePlacementClosesOnlyThePane() throws Exception {
         FakeHerdr herdr = new FakeHerdr();