CB-108: fleet-management MCP tools (bridge_spawn / bridge_list / bridge_stop)

The primary could delegate to a worker but not create or reap one over MCP —
spawning was a raw REST POST /workers. BridgeMcp now adapts WorkerService so a
worker's whole lifecycle runs through MCP: bridge_spawn returns the new worker's
sessionId (for bridge_send) and paneId (for bridge_stop); bridge_list projects the
tracked workers; bridge_stop tears one down. The subscription boundary stays
enforced inside WorkerService (bridge_spawn surfaces a guard breach as a tool error
without touching herdr). Tools are thin static adapters, unit-tested by parity.

bridged/src/test/java/dev/ltms/bridged/mcp/BridgeMcpTest.java

@@ -1,13 +1,18 @@
 package dev.ltms.bridged.mcp;
 
+import dev.ltms.bridged.config.BridgedConfig;
+import dev.ltms.bridged.guard.SubscriptionGuard;
 import dev.ltms.bridged.herdr.AgentControl;
 import dev.ltms.bridged.herdr.FakeHerdr;
+import dev.ltms.bridged.herdr.WorkspaceControl;
 import dev.ltms.bridged.inject.Injector;
 import dev.ltms.bridged.msg.MessageService;
 import dev.ltms.bridged.msg.Rendezvous;
+import dev.ltms.bridged.worker.WorkerService;
 import io.modelcontextprotocol.spec.McpSchema;
 import org.junit.jupiter.api.Test;
 
+import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.TimeUnit;
 
@@ -29,6 +34,14 @@ class BridgeMcpTest {
         return ((McpSchema.TextContent) r.content().getFirst()).text();
     }
 
+    private static WorkerService workerService(FakeHerdr h, String baseUrl, Set<String> allow) {
+        BridgedConfig.Worker cfg = new BridgedConfig.Worker(
+                "ltms-local", baseUrl, "coder", null, "BRIDGED_WORKER_TOKEN", null,
+                "tab", "bridged-workers", "worker: {profile} #{n}", null);
+        return new WorkerService(new AgentControl(h), new WorkspaceControl(h),
+                new SubscriptionGuard(allow), cfg, _ -> "tok");
+    }
+
     @Test
     void sendThenReplyRoundTrips() throws Exception {
         // bridge_send blocks; bridge_reply resolves it with the worker's structured answer.
@@ -106,6 +119,48 @@ class BridgeMcpTest {
         assertTrue(textOf(res).contains("no send is awaiting"));
     }
 
+    @Test
+    void spawnReturnsTheNewWorkersSessionAndPane() {
+        FakeHerdr h = new FakeHerdr();
+        McpSchema.CallToolResult res = BridgeMcp.spawn(workerService(h, "http://gx00.gw:8000", Set.of("gx00.gw")));
+        assertNotEquals(Boolean.TRUE, res.isError());
+        String out = textOf(res);
+        assertTrue(out.contains("\"sessionId\":\"term_new\""), out);
+        assertTrue(out.contains("\"paneId\":\"w9:pW\""), out);
+    }
+
+    @Test
+    void spawnRejectsAnOffAllowlistProfileWithoutTouchingHerdr() {
+        FakeHerdr h = new FakeHerdr();
+        McpSchema.CallToolResult res = BridgeMcp.spawn(workerService(h, "https://api.anthropic.com", Set.of("gx00.gw")));
+        assertTrue(res.isError());
+        assertTrue(textOf(res).contains("subscription boundary"));
+        assertFalse(h.called("agent.start"), "the guard must block before any spawn");
+    }
+
+    @Test
+    void listReportsTrackedWorkers() {
+        FakeHerdr h = new FakeHerdr();
+        McpSchema.CallToolResult res = BridgeMcp.listWorkers(workerService(h, "http://gx00.gw:8000", Set.of("gx00.gw")));
+        assertNotEquals(Boolean.TRUE, res.isError());
+        assertTrue(textOf(res).contains("\"sessionId\":\"term_a\""), textOf(res));
+    }
+
+    @Test
+    void stopTearsDownAWorkerByPane() {
+        FakeHerdr h = new FakeHerdr();
+        McpSchema.CallToolResult res = BridgeMcp.stop(workerService(h, "http://gx00.gw:8000", Set.of("gx00.gw")), "w9:pW");
+        assertNotEquals(Boolean.TRUE, res.isError());
+        assertEquals("stopped w9:pW", textOf(res));
+        assertTrue(h.called("pane.close"));
+    }
+
+    @Test
+    void stopRequiresAPaneId() {
+        FakeHerdr h = new FakeHerdr();
+        assertTrue(BridgeMcp.stop(workerService(h, "http://gx00.gw:8000", Set.of("gx00.gw")), "  ").isError());
+    }
+
     @Test
     void statusReportsLiveAgentStatus() {
         FakeHerdr blocked = new FakeHerdr().agentStatus("blocked");