CB-517: add bridge_whoami and make the bridge prompt a portable charter

The communication rules lived only in two opt-in skills, so nothing
always-on told the primary how to orchestrate and nothing guaranteed a
worker loaded its playbook. Move protocol and policy into CLAUDE.md,
which a worker inherits for free (its worktree is a checkout of this
repo), and leave the skills as pure per-job procedure.

bridge_whoami closes the load-bearing gap: every tool already consumed
the caller identity ConnectionIdentity resolves from the connection, but
none reported it, so an agent had to infer its own role from side
channels the daemon does not control. Guessing fails asymmetrically — a
primary acting as a worker is refused by the authz gate and learns at
once, while a worker acting as the primary ends its turn without
bridge_reply and the sender silently receives nothing. The tool reuses
the same Principal the gate is built on, so the two cannot disagree; the
primary gets role only (handing it a sessionId it does not own would
invite the forged reply Authz refuses), and a worker missing from the
registry still gets role + sessionId rather than 'unknown'.

The CLAUDE.md block is written to be copied as-is into any project that
mounts the bridge: repo-local details (Authz paths, the .mcp.json/wiki
exclusions, the skill names) moved below it into a project addendum, and
every role-inference fallback is stated one-way — the mount-name signal
only holds for mcp__bridge__* (the launcher fixes it), not for the
primary's mount, which each project names itself. The wiki carries the
block verbatim as the template, with a sync check.

Because this repo IS the bridge, that block is shipped surface, not
documentation: the addendum adds a mandatory checklist mapping each part
of the code to the part of the prompt it can invalidate.

Also: delegate-by-default policy for the primary — the test is not 'could
I do this faster myself' but 'can I write a brief good enough for a
worker'.

mvn clean install: 356 tests green (353 + 3 for whoami); ide_diagnostics
clean on both changed files.

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

@@ -1,5 +1,6 @@
 package dev.ltms.bridged.mcp;
 
+import dev.ltms.bridged.auth.Principal;
 import dev.ltms.bridged.config.BridgedConfig;
 import dev.ltms.bridged.guard.SubscriptionGuard;
 import dev.ltms.bridged.herdr.AgentControl;
@@ -343,4 +344,58 @@ class BridgeMcpTest {
         assertNotEquals(Boolean.TRUE, res.isError());
         assertEquals("blocked", textOf(res));
     }
+
+    // --- bridge_whoami: the caller's own identity, so an agent never has to guess its role -------
+
+    @Test
+    void whoamiReportsThePrimaryAsPrimaryAndNothingElse() {
+        FakeHerdr h = new FakeHerdr();
+        McpSchema.CallToolResult res = BridgeMcp.whoami(
+                Principal.primary(100), sessionManager(h, "http://gx00.gw:8000", Set.of("gx00.gw")));
+
+        assertNotEquals(Boolean.TRUE, res.isError());
+        String out = textOf(res);
+        assertTrue(out.contains("\"role\":\"primary\""), out);
+        // The primary owns no session — leaking a sessionId here would invite it to reply as one.
+        assertFalse(out.contains("sessionId"), out);
+    }
+
+    @Test
+    void whoamiReportsAWorkerWithItsRegisteredSession() {
+        FakeHerdr h = new FakeHerdr();
+        FakeWorktrees worktrees = new FakeWorktrees().withRepoRoot("/repo").withPrefix("/wt");
+        SessionManager sessions = new SessionManager(
+                workerService(h, "http://gx00.gw:8000", Set.of("gx00.gw")), worktrees);
+        WorkerSession s = sessions.acquire("ltms-local", null, "/caller/proj", "term_primary",
+                new WorktreeRequest("cb-517", null));
+
+        McpSchema.CallToolResult res = BridgeMcp.whoami(Principal.worker(s.terminalId(), 200), sessions);
+
+        assertNotEquals(Boolean.TRUE, res.isError());
+        String out = textOf(res);
+        assertTrue(out.contains("\"role\":\"worker\""), out);
+        assertTrue(out.contains("\"sessionId\":\"" + s.terminalId() + "\""), out);
+        assertTrue(out.contains("\"profile\":\"ltms-local\""), out);
+        assertTrue(out.contains("\"worktree\":\"" + s.worktree() + "\""), out);
+        assertTrue(out.contains("\"branch\":\"" + s.branch() + "\""), out);
+        assertTrue(out.contains("\"owner\":\"term_primary\""), out);
+    }
+
+    /**
+     * A worker the registry has no record of — it outlived a daemon restart — must still learn the
+     * load-bearing fact. Degrading to "I don't know who you are" would put it back to guessing,
+     * which is the failure this tool exists to remove.
+     */
+    @Test
+    void whoamiStillReportsWorkerRoleWhenTheSessionIsUnregistered() {
+        FakeHerdr h = new FakeHerdr();
+        McpSchema.CallToolResult res = BridgeMcp.whoami(Principal.worker("term_orphan", 200),
+                sessionManager(h, "http://gx00.gw:8000", Set.of("gx00.gw")));
+
+        assertNotEquals(Boolean.TRUE, res.isError());
+        String out = textOf(res);
+        assertTrue(out.contains("\"role\":\"worker\""), out);
+        assertTrue(out.contains("\"sessionId\":\"term_orphan\""), out);
+        assertFalse(out.contains("profile"), out); // nothing invented for a session we don't track
+    }
 }