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

@@ -694,7 +694,7 @@ public final class Fleetd {
         }, outagePolicy);
 
         FleetMcp mcp = new FleetMcp(messages, workers, sessions, identity, presence,
-                primaryRegistry, callers, metrics,
+                primaryRegistry, callers, FleetMcp.AuthorizationMode.ENFORCED, metrics,
                 capacitySource(config, cfg, profile -> liveCountRef.get().apply(profile)),
                 new FleetMcp.HealthCoverageSource(() -> {
                     var health = config.get().health();

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

@@ -93,7 +93,18 @@ public final class FleetMcp {
 
     private final HttpServletStreamableServerTransportProvider transport;
     private final McpSyncServer server;
-    private final CallerResolver authz; // CB-501: null → authorization not enforced (legacy)
+    /**
+     * fleetd #518: whether {@link #denyFor} enforces the CB-505 policy table at all. Replaces the
+     * old {@code CallerResolver authz} field, whose null-ness used to decide BOTH this AND which
+     * principal-resolution code path {@link #contextExtractor} ran — reaching "authorization off"
+     * by simply not passing a {@link CallerResolver} also meant the resolved {@link Principal}
+     * came from a second, separately-maintained heuristic ({@code legacyPrincipal}, now deleted)
+     * that nothing ever exercised. There is now exactly one resolution path ({@code callers},
+     * required and non-null below) and a separate, explicitly-chosen {@link AuthorizationMode}
+     * for this flag — so a caller can turn enforcement off without silently swapping in a second,
+     * untested identity heuristic.
+     */
+    private final boolean authorizationEnforced;
     private final Metrics metrics;      // CB-502: null → auth failures not counted
     private final CapacitySource capacity;
     private final HealthCoverageSource healthCoverage;
@@ -250,6 +261,17 @@ public final class FleetMcp {
         public static CoordinationSource none() { return new CoordinationSource(null, List.of()); }
     }
 
+    /**
+     * fleetd #518: whether {@link #denyFor} enforces the CB-505 policy table. A required
+     * constructor parameter with no default, so "authorization is off" can only be reached by a
+     * caller explicitly saying so — never by omitting a {@link CallerResolver} the way the old
+     * {@code callers == null} idiom allowed. {@code callers} itself is required either way: even
+     * under {@link #UNENFORCED}, the one real {@link CallerResolver} still resolves every caller's
+     * {@link Principal} (so {@code markSpawnedMemberPresent}/{@code recordPrimarySingleton} see a
+     * real identity), and {@link #denyFor} is the only thing that changes.
+     */
+    public enum AuthorizationMode { ENFORCED, UNENFORCED }
+
     /**
      * The only constructor (fleetd #480 Unit C correction round). Every field below used to have
      * its own defaulting overload — {@code leadChannel}/{@code outage}/{@code leadSeats}/
@@ -268,10 +290,16 @@ public final class FleetMcp {
      * {@link OutageSource#none()}, {@link LeadSeatSource#none()}, {@code List.of()} are all still
      * perfectly fine values, just never an implicit default reached by omission.
      *
-     * @param callers      resolves each call's {@link Principal}; {@code null} disables
-     *                     authorization. This surface needs its own enforcement: {@code /mcp} is a
-     *                     raw servlet on Jetty's context handler and never passes through
-     *                     Javalin's {@code before} filter, so the REST guard does not cover it.
+     * @param callers      resolves each call's {@link Principal}. Required, never {@code null} —
+     *                     fleetd #518: use {@link AuthorizationMode#UNENFORCED} to disable
+     *                     enforcement, not a missing resolver. This surface needs its own
+     *                     enforcement: {@code /mcp} is a raw servlet on Jetty's context handler and
+     *                     never passes through Javalin's {@code before} filter, so the REST guard
+     *                     does not cover it.
+     * @param authorizationMode fleetd #518: whether {@link #denyFor} enforces the CB-505 policy
+     *                     table ({@link AuthorizationMode#ENFORCED}) or leaves the gate open
+     *                     ({@link AuthorizationMode#UNENFORCED}, for the pre-CB-513 test suite that
+     *                     does not exercise authorization). Required, with no default.
      * @param metrics      registry for auth-failure counting; may be {@code null}
      * @param quarantine   CB-578 stage B facts for {@code fleet_profiles}; pass
      *                     {@link QuarantineSource#none()} for a caller that does not want the
@@ -301,9 +329,13 @@ public final class FleetMcp {
      */
     public FleetMcp(MessageService messages, PeerLauncher workers, SessionManager sessions,
                      ConnectionIdentity identity, MemberPresence presence, PrimaryRegistry primaryRegistry,
-                      CallerResolver callers, Metrics metrics, CapacitySource capacity, HealthCoverageSource healthCoverage,
+                      CallerResolver callers, AuthorizationMode authorizationMode, Metrics metrics,
+                      CapacitySource capacity, HealthCoverageSource healthCoverage,
                       QuarantineSource quarantine, LeadChannel leadChannel, OutageSource outage,
                       LeadSeatSource leadSeats, List<String> peers, LeadRollover leadRollover) {
+        Objects.requireNonNull(callers, "callers");
+        this.authorizationEnforced = Objects.requireNonNull(authorizationMode, "authorizationMode")
+                == AuthorizationMode.ENFORCED;
         this.leadChannel = leadChannel;
         this.peers = peers == null ? List.of() : List.copyOf(peers);
         this.capacity = capacity;
@@ -322,11 +354,11 @@ public final class FleetMcp {
                 // (CB-113) — its MCP initialize is the reliable "the agent is up" signal.
                 .contextExtractor(req -> {
                     // One resolution per call, shared with the REST surface via CallerResolver so
-                    // the two paths cannot drift on who a caller is.
-                    Principal p = callers != null
-                            ? callers.resolve(req.getRemoteAddr(), req.getRemotePort(),
-                                    req.getHeader("Authorization"))
-                            : legacyPrincipal(identity, req.getRemoteAddr(), req.getRemotePort());
+                    // the two paths cannot drift on who a caller is. fleetd #518: callers is
+                    // required (never null) so there is no second, untested resolution path to
+                    // fall back to here — AuthorizationMode governs enforcement, not identity.
+                    Principal p = callers.resolve(req.getRemoteAddr(), req.getRemotePort(),
+                            req.getHeader("Authorization"));
                     // CB-532: guard on the ROLE, not on the terminal being null. This excludes a
                     // lead, which carries its pane too, while including every spawned member role.
                     // Enrolling a lead would count it as an available member in the roster.
@@ -443,7 +475,7 @@ public final class FleetMcp {
                     McpSchema.CallToolResult denied = deny(exchange, toolAction("fleet_list", Map.of()), null);
                     if (denied != null) return denied;
                     return listFleet(workers, sessions, messages, capacity, healthCoverage, quarantine, outage,
-                            leadSeats, callers == null ? Map.of() : callers.leads(),
+                            leadSeats, callers.leads(),
                             callerTerminal(exchange),
                             new CoordinationSource(leadChannel, peers),
                             coordinatorVisibleTo(principal(exchange)));
@@ -522,35 +554,9 @@ public final class FleetMcp {
                 .toolCall(fleetWhoami, whoamiHandler)
                 .toolCall(fleetHandover, handoverHandler)
                 .build();
-        this.authz = callers;
         this.metrics = metrics;
     }
 
-    /**
-     * Pre-CB-501 identity: worker if the connection maps to a pane, otherwise anonymous. Used
-     * only by the legacy constructor ({@code callers == null}), where authorization is not
-     * enforced anyway — but the resolved {@link Principal} still reaches non-authz logic (e.g.
-     * {@code markSpawnedMemberPresent}, {@code recordPrimarySingleton}), so it must not be trusted
-     * with a role it did not earn.
-     *
-     * <p>fleetd #509: this used to fall back to {@link Principal#primary}, unconditionally, for
-     * every caller the connection did not resolve to a worker pane — with none of
-     * {@code CallerResolver.java:254}'s two guards ({@code isLoopback}, {@code scanComplete}).
-     * That is the exact shape #317 and #505 each closed on the enforced path; this branch was the
-     * same trap, left open on the legacy one. It now returns {@link Principal#anonymous} instead,
-     * so an unresolved legacy caller earns no authority rather than the primary's.
-     *
-     * <p>Package-private (was {@code private}) so this is unit-testable directly, the same reason
-     * {@link #denyFor} was split out — it runs inside a contextExtractor closure that only fires on
-     * a real MCP request, so nothing else could pin this behaviour.
-     */
-    static Principal legacyPrincipal(ConnectionIdentity identity, String addr, int port) {
-        ConnectionIdentity.Caller c = identity.resolve(addr, port);
-        return c.terminal() != null
-                ? Principal.worker(c.terminal(), c.pid())
-                : Principal.anonymous();
-    }
-
     /** The caller reconstructed from the transport context. */
     private static Principal principal(McpSyncServerExchange exchange) {
         return principalFrom(exchange.transportContext().get(CALLER_ROLE),
@@ -605,8 +611,8 @@ public final class FleetMcp {
     McpSchema.CallToolResult denyFor(Principal caller, Authz.Action action, String target) {
         // The enforcement switch lives HERE rather than in the exchange-facing wrapper: any future
         // tool that calls this directly must not be able to skip the gate by accident.
-        if (authz == null) {
-            return null; // legacy constructor: authorization not enforced
+        if (!authorizationEnforced) {
+            return null; // AuthorizationMode.UNENFORCED: authorization not enforced (fleetd #518)
         }
         if (Authz.permits(caller, action, target)) {
             if (action != Authz.Action.READ) {

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

@@ -78,10 +78,15 @@ class FleetMcpAuthzTest {
         // fleetd #480 correction round: FleetMcp has one constructor now (no defaulting
         // overloads — see its javadoc), so every feature this test does not exercise is passed
         // its explicit "off" value here rather than being omitted.
+        //
+        // fleetd #518: callers is now required (never null) either way — the resolver that used
+        // to be omitted to reach "legacy" is now always real, and AuthorizationMode is the
+        // separate, explicit choice that governs enforcement.
         mcp = new FleetMcp(messages, workers, sessions, identity, sessions.asPresence(),
                 new PrimaryRegistry(null),
-                enforce ? CallerResolver.withLeadsAndMembers(identity, false, null,
-                Map::of, new MemberRegistry(null)) : null,
+                CallerResolver.withLeadsAndMembers(identity, false, null,
+                Map::of, new MemberRegistry(null)),
+                enforce ? FleetMcp.AuthorizationMode.ENFORCED : FleetMcp.AuthorizationMode.UNENFORCED,
                 metrics, FleetMcp.CapacitySource.none(), new FleetMcp.HealthCoverageSource(() -> "off"),
                 FleetMcp.QuarantineSource.none(), null, FleetMcp.OutageSource.none(),
                 FleetMcp.LeadSeatSource.none(), List.of(), null);
@@ -187,28 +192,31 @@ class FleetMcpAuthzTest {
         // The 22 pre-existing FleetMcpTest cases rely on no authorization being enforced.
         FleetMcp m = mcp(false);
         assertNull(m.denyFor(ANON, Authz.Action.SPAWN, null),
-                "no CallerResolver supplied ⇒ authorization not enforced (legacy behaviour)");
+                "AuthorizationMode.UNENFORCED chosen explicitly ⇒ authorization not enforced "
+                        + "(legacy behaviour) — fleetd #518 replaced the old callers == null idiom");
     }
 
     /**
-     * fleetd #509: {@code legacyPrincipal} (used only when {@code callers == null}, i.e. the
-     * legacy constructor above) used to fall back to {@link Principal#primary} for ANY caller the
-     * connection did not resolve to a worker pane — no {@code isLoopback} check, no
-     * {@code scanComplete} check, unlike the enforced path's {@code CallerResolver.java:254}. A
-     * non-loopback caller (an off-host client) is exactly the case that must never earn the
-     * primary's authority, and authorization being disabled in legacy mode does not make that
-     * safe: the resolved {@link Principal} still reaches non-authz logic such as
-     * {@code markSpawnedMemberPresent} and {@code recordPrimarySingleton}.
+     * fleetd #509 was originally proven against {@code FleetMcp.legacyPrincipal} — a second,
+     * separately-maintained principal-resolution heuristic that only ran when {@code callers} was
+     * omitted (null). fleetd #518 deleted that whole heuristic: {@code callers} is now required
+     * and non-null under every {@link FleetMcp.AuthorizationMode}, so the ONE real
+     * {@link CallerResolver} resolves every caller, enforced or not, and #509's property (a
+     * non-loopback / unresolved caller must never earn the primary's authority) is exactly what
+     * {@code CallerResolverTest.aNonLoopbackCallerIsNeverThePrimaryUnderLoopbackTrust} already
+     * proves on that one real path. There is no longer a second heuristic here to test.
      */
     @Test
-    void legacyPrincipalIsAnonymousNotPrimaryForAnUnresolvedCaller() {
+    void anUnresolvedNonLoopbackCallerIsAnonymousUnderTheOneRealResolver() {
         ConnectionIdentity identity = new ConnectionIdentity(new PaneLocator(herdr), _ -> 999_999);
+        CallerResolver resolver = CallerResolver.withLeadsAndMembers(identity, false, null,
+                Map::of, new MemberRegistry(null));
         // A non-loopback address never even reaches the pane scan — resolve() short-circuits it
         // to Caller(null, -1, true), the same "no terminal" shape a genuine primary's connection
-        // produces. legacyPrincipal must not conflate the two.
-        Principal p = FleetMcp.legacyPrincipal(identity, "8.8.8.8", 1234);
+        // produces on loopback. The real resolver must not conflate the two.
+        Principal p = resolver.resolve("8.8.8.8", 1234, null);
         assertEquals(Principal.anonymous(), p,
-                "an unresolved legacy caller must earn no authority, not the primary's");
+                "an unresolved, non-loopback caller must earn no authority, not the primary's");
     }
 
     // --- fleetd #439: who may see fleet_list's coordinator row ----------------------------------

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

@@ -0,0 +1,147 @@
+package dev.ltms.fleet.mcp;
+
+import dev.ltms.fleet.auth.CallerResolver;
+import dev.ltms.fleet.auth.MemberRegistry;
+import dev.ltms.fleet.config.FleetConfig;
+import dev.ltms.fleet.guard.SubscriptionGuard;
+import dev.ltms.fleet.herdr.AgentControl;
+import dev.ltms.fleet.herdr.FakeHerdr;
+import dev.ltms.fleet.herdr.PaneLocator;
+import dev.ltms.fleet.herdr.WorkspaceControl;
+import dev.ltms.fleet.inject.Injector;
+import dev.ltms.fleet.member.ClaudeCodeLauncher;
+import dev.ltms.fleet.msg.InMemoryReplyInbox;
+import dev.ltms.fleet.msg.MessageService;
+import dev.ltms.fleet.msg.Rendezvous;
+import dev.ltms.fleet.session.FakeWorktrees;
+import dev.ltms.fleet.session.SessionManager;
+import io.modelcontextprotocol.client.McpClient;
+import io.modelcontextprotocol.client.McpSyncClient;
+import io.modelcontextprotocol.client.transport.HttpClientStreamableHttpTransport;
+import io.modelcontextprotocol.spec.McpClientTransport;
+import io.modelcontextprotocol.spec.McpSchema;
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.server.ServerConnector;
+import org.eclipse.jetty.servlet.ServletContextHandler;
+import org.eclipse.jetty.servlet.ServletHolder;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+
+import java.net.http.HttpRequest;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * fleetd #518 — Part 2: drive the {@code contextExtractor} closure for real.
+ *
+ * <p>{@code FleetMcp.deny()}/{@code denyFor()} has a full policy table of tests
+ * ({@code FleetMcpAuthzTest}), and {@code CallerResolver.resolve()} has its own full suite
+ * ({@code CallerResolverTest}). Neither one ever exercises the closure that WIRES them together
+ * inside {@code FleetMcp}'s constructor: it is built once, handed to the MCP SDK's transport, and
+ * only ever runs when a real MCP client makes a real HTTP request. Every existing test either
+ * calls {@code denyFor(Principal, ...)} with a hand-built {@link dev.ltms.fleet.auth.Principal}
+ * (never asking who the transport would actually have resolved) or drives a static handler method
+ * directly. A mutation that swapped the whole resolution decision for an unconditional fallback —
+ * bypassing {@link CallerResolver} entirely — passed the full suite, including every
+ * {@code FleetMcpAuthzTest} case, because none of them go through the transport at all.
+ *
+ * <p>This test boots the real {@code HttpServletStreamableServerTransportProvider} on a real
+ * Jetty server, drives it with a real MCP client over HTTP, and checks a result that only the
+ * real {@link CallerResolver} can produce: token-mode inspects the {@code Authorization} header
+ * and grants {@code PRIMARY} only for the right bearer token. The connection never resolves to a
+ * worker pane (the fake peer-pid lookup always misses), so the ONLY way {@code fleet_whoami} can
+ * come back as {@code primary} is if the closure actually called {@code callers.resolve(...)} and
+ * read that header — a behaviour the deleted {@code legacyPrincipal} heuristic never had at all.
+ */
+class FleetMcpContextExtractorTest {
+
+    private static final String TOKEN = "s3cret-mcp-token";
+
+    private final FakeHerdr herdr = new FakeHerdr();
+    private final AgentControl agents = new AgentControl(herdr);
+    private FleetMcp mcp;
+    private Server server;
+
+    @AfterEach
+    void tearDown() throws Exception {
+        if (server != null) {
+            server.stop();
+        }
+        if (mcp != null) {
+            mcp.close();
+        }
+    }
+
+    @Test
+    void aRealMcpRequestIsResolvedByTheRealCallerResolverNotAFallback() throws Exception {
+        FleetConfig.Profile cfg = new FleetConfig.Profile(
+                "ltms-local", "http://gx00.gw:8000", "coder", null, "FLEETD_WORKER_TOKEN", null,
+                "tab", "fleetd-workers", "worker: {profile} #{n}", null, null, null);
+        ClaudeCodeLauncher workers = new ClaudeCodeLauncher(agents, new WorkspaceControl(herdr),
+                new SubscriptionGuard(Set.of("gx00.gw")), Map.of(cfg.profile(), cfg), cfg.profile(),
+                _ -> "tok");
+        SessionManager sessions = new SessionManager(workers, new FakeWorktrees());
+        MessageService messages = new MessageService(agents, new Injector(agents), new Rendezvous(),
+                new InMemoryReplyInbox());
+        // The peer-pid lookup always misses (-1), so no connection here is ever resolved to a
+        // worker pane — every call falls through to CallerResolver's token check, the one branch
+        // that is unreachable through the deleted legacy heuristic.
+        ConnectionIdentity identity = new ConnectionIdentity(new PaneLocator(herdr), _ -> -1);
+        CallerResolver callers = CallerResolver.withLeadsAndMembers(identity, true, TOKEN,
+                Map::of, new MemberRegistry(null));
+
+        mcp = new FleetMcp(messages, workers, sessions, identity, sessions.asPresence(),
+                new PrimaryRegistry(null), callers, FleetMcp.AuthorizationMode.ENFORCED,
+                null, FleetMcp.CapacitySource.none(), new FleetMcp.HealthCoverageSource(() -> "off"),
+                FleetMcp.QuarantineSource.none(), null, FleetMcp.OutageSource.none(),
+                FleetMcp.LeadSeatSource.none(), List.of(), null);
+
+        ServletContextHandler handler = new ServletContextHandler();
+        handler.setContextPath("/");
+        handler.addServlet(new ServletHolder(mcp.servlet()), "/mcp");
+        server = new Server(0);
+        server.setHandler(handler);
+        server.start();
+        String baseUrl = "http://127.0.0.1:"
+                + ((ServerConnector) server.getConnectors()[0]).getLocalPort();
+
+        // The right bearer token: the real CallerResolver grants PRIMARY, which fleet_whoami's
+        // READ gate lets through.
+        McpSchema.CallToolResult authorized = callWhoami(baseUrl, "Bearer " + TOKEN);
+        assertFalse(authorized.isError(), "a valid bearer token must resolve as PRIMARY and pass "
+                + "fleet_whoami's READ gate: " + textOf(authorized));
+        assertTrue(textOf(authorized).contains("\"role\":\"primary\""),
+                "fleet_whoami must report the role the real CallerResolver resolved over this "
+                        + "connection, not a fallback: " + textOf(authorized));
+
+        // No credential at all, over the SAME wiring: the real resolver refuses it as ANONYMOUS.
+        // legacyPrincipal never looked at the Authorization header, so it could not have told
+        // these two calls apart at all -- this is the assertion the deleted mutation would fail.
+        McpSchema.CallToolResult unauthorized = callWhoami(baseUrl, null);
+        assertTrue(unauthorized.isError(), "no credential must be refused, not silently let "
+                + "through: " + textOf(unauthorized));
+    }
+
+    private static McpSchema.CallToolResult callWhoami(String baseUrl, String authorizationHeader) {
+        HttpRequest.Builder requestTemplate = HttpRequest.newBuilder();
+        if (authorizationHeader != null) {
+            requestTemplate.header("Authorization", authorizationHeader);
+        }
+        McpClientTransport transport = HttpClientStreamableHttpTransport.builder(baseUrl)
+                .endpoint("/mcp")
+                .requestBuilder(requestTemplate)
+                .build();
+        try (McpSyncClient client = McpClient.sync(transport).build()) {
+            client.initialize();
+            return client.callTool(McpSchema.CallToolRequest.builder("fleet_whoami").arguments(Map.of()).build());
+        }
+    }
+
+    private static String textOf(McpSchema.CallToolResult r) {
+        return ((McpSchema.TextContent) r.content().getFirst()).text();
+    }
+}

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

@@ -89,6 +89,7 @@ class FleetMcpHandoverTest {
         mcp = new FleetMcp(messages, workers, sessions, identity, sessions.asPresence(),
                 new PrimaryRegistry(null),
                 CallerResolver.withLeadsAndMembers(identity, false, null, Map::of, new MemberRegistry(null)),
+                FleetMcp.AuthorizationMode.ENFORCED,
                 null, FleetMcp.CapacitySource.none(), new FleetMcp.HealthCoverageSource(() -> "off"),
                 FleetMcp.QuarantineSource.none(), null, FleetMcp.OutageSource.none(),
                 FleetMcp.LeadSeatSource.none(), List.of(), leadRollover);