fleetd #669 Unit C: add the COLLABORATOR role and its authorization row

Adds Role.COLLABORATOR, Principal.collaborator(), and the Authz.permits grant:
READ/METRICS open, REPLY/ASK via ownership, SEND limited to a configured lead
or collaborator via a new classifier parameter, everything else denied.
isSpawnedMember() stays WORKER || ARCHITECT. fleet_whoami reports role and
collaborator name with no leader key.

Per a same-day ticket correction, the existing 3-argument Authz.permits is
kept (fail-closed default via the new NO_KNOWN_LEAD_OR_COLLABORATOR
classifier) rather than deleted, so the 47 pre-existing call sites in
AuthzTest/CallerResolverTest are untouched; both production gates
(FleetMcp#denyFor, FleetApp#allow via the new permitsFor seam) call the
4-argument form explicitly with the shared constant.

Mutation-verified: removing the classifier conjunct from the SEND arm kills
exactly 3 tests (AuthzTest, FleetMcpAuthzTest, FleetAppAuthTest), one per
gate, no cascade.

Full mvn clean install at this commit: 1974 tests, 0 failures (baseline at
f0ff252 was 1964; +10 are the new collaborator-matrix tests). Independently
counted from target/surefire-reports/*.xml after rm -rf: 173 report files,
aggregate tests=1974 failures=0 errors=0.

fleetd/src/main/java/dev/ltms/fleet/auth/Authz.java

@@ -1,5 +1,7 @@
 package dev.ltms.fleet.auth;
 
+import java.util.function.Predicate;
+
 /**
  * The authorization table (CB-505), stated once and enforced on both entry paths.
  *
@@ -60,58 +62,92 @@ public final class Authz {
     }
 
     /**
-     * Whether {@code caller} may perform {@code action} against {@code targetSession}.
-     *
-     * @param targetSession the session id in the request path; only consulted for the worker-scoped
-     *                      actions ({@code REPLY}, {@code ASK}), ignored otherwise, may be
-     *                      {@code null}
+     * Stands in for the terminal-to-tab registry a collaborator's {@code SEND} is checked
+     * against, until one exists: answers no for every target, so a collaborator reaches nothing
+     * today. Both production gates ({@code FleetMcp#denyFor}, {@code FleetApp#allow}) pass this
+     * exact instance, so the classifier is defined once and replacing it is a one-line change in
+     * each.
+     */
+    public static final Predicate<String> NO_KNOWN_LEAD_OR_COLLABORATOR = target -> false;
+
+    /**
+     * Convenience form for a caller with no classifier to supply. Fails closed: a collaborator's
+     * {@code SEND} is refused, as if no terminal were a configured lead or collaborator — the
+     * same decision {@link #NO_KNOWN_LEAD_OR_COLLABORATOR} gives explicitly. Every other action's
+     * result is identical to the four-argument form's, since none of them consult the classifier.
      */
     public static boolean permits(Principal caller, Action action, String targetSession) {
+        return permits(caller, action, targetSession, NO_KNOWN_LEAD_OR_COLLABORATOR);
+    }
+
+    /**
+     * Whether {@code caller} may perform {@code action} against {@code targetSession}.
+     *
+     * @param targetSession           the session id in the request path; only consulted for the
+     *                                worker-scoped actions ({@code REPLY}, {@code ASK}) and for a
+     *                                collaborator's {@code SEND}, ignored otherwise, may be
+     *                                {@code null}
+     * @param knownLeadOrCollaborator whether a terminal is a configured lead or collaborator —
+     *                                consulted only for a collaborator's {@code SEND}, to confine
+     *                                it to another named peer and never a spawned member's
+     *                                terminal
+     */
+    public static boolean permits(Principal caller, Action action, String targetSession,
+                                   Predicate<String> knownLeadOrCollaborator) {
         if (caller == null || caller.isAnonymous()) {
             return false; // authenticated as nothing ⇒ authorized for nothing
         }
         return switch (action) {
-            // Fleet lifecycle is the primary's alone — spawn, stop, drain. An architect
-            // deliberately does NOT get these (CB-548), so it cannot tear down or stand up workers
-            // even though it coordinates them; and a worker driving any of these would be a worker
-            // escalating into the orchestrator role.
+            // Fleet lifecycle is the primary's alone — spawn, stop, drain. An architect and a
+            // collaborator deliberately do NOT get these, so neither can tear down or stand up
+            // workers even though one of them coordinates them; and a worker driving any of these
+            // would be a worker escalating into the orchestrator role.
             case SPAWN, STOP, DRAIN, HANDOVER -> caller.isPrimary();
 
-            // Delivering a turn to a local session is open to the primary and the architect: an
-            // architect delegates to workers (that is the role's point) but still has no lifecycle
-            // rights. A worker is excluded — sending would be it escalating.
-            case SEND -> caller.isPrimary() || caller.isArchitect();
+            // Delivering a turn to a local session is open to the primary, the architect, and a
+            // collaborator whose target is itself a configured lead or collaborator: the architect
+            // delegates to workers (that is the role's point); a collaborator may reach only
+            // another named peer, never a spawned member's terminal. A worker is excluded —
+            // sending would be it escalating.
+            case SEND -> caller.isPrimary() || caller.isArchitect()
+                    || (caller.isCollaborator() && knownLeadOrCollaborator.test(targetSession));
 
-            // Same grant as SEND. Resolving a worker's blocked question is part of delegating to
-            // it, not a separate capability.
+            // Resolving a worker's blocked question is part of delegating to it, open to the same
+            // two roles that may stand up that delegation in the first place. Not a collaborator:
+            // resuming another session's turn is lifecycle-adjacent, not peer messaging.
             case ANSWER -> caller.isPrimary() || caller.isArchitect();
 
-            // Same grant as SEND. This leaves the daemon over the coordination broker rather than
-            // addressing a local session, but the caller who may do one may do the other.
+            // Leaves the daemon over the coordination broker rather than addressing a local
+            // session, open to the same two roles as ANSWER. Not a collaborator: it is a
+            // local-tab peer with no cross-host route.
             case COORD_SEND -> caller.isPrimary() || caller.isArchitect();
 
             // The load-bearing rule: a caller acts only as the pane it occupies. CB-532 widened who
             // that can be — a lead answering another lead is replying for its OWN terminal, which
             // this already permits — while the rule itself is unchanged, and is what stops anyone
-            // forging a reply for a rendezvous someone else is waiting on. An architect's own pane
-            // passes through the same check, so it can answer a funnel that delegated to it. An
-            // unnamed primary (token/loopback, no pane) owns nothing and is still excluded.
+            // forging a reply for a rendezvous someone else is waiting on. An architect's or a
+            // collaborator's own pane passes through the same check, so each can answer a funnel
+            // that delegated to it. An unnamed primary (token/loopback, no pane) owns nothing and
+            // is still excluded.
             case REPLY, ASK -> caller.ownsSession(targetSession);
 
             // READ is roster, profile, and identity observation — fleet_list, fleet_profiles, and
             // fleet_whoami — and carries no secrets: no ticket reply, no pending question, and no
             // other session's turn state. Those live under TASK_READ. METRICS is the separate
-            // Prometheus scrape. Both stay open to every authenticated role.
-            case READ, METRICS -> caller.isPrimary() || caller.isWorker() || caller.isArchitect();
+            // Prometheus scrape. Both are open to every authenticated role, including a
+            // collaborator.
+            case READ, METRICS -> caller.isPrimary() || caller.isWorker() || caller.isArchitect()
+                    || caller.isCollaborator();
 
-            // Ticket polling and session status, open to every authenticated role the same as READ.
-            // Unlike READ, a holder may poll a ticket it did not create, or read another session's
-            // pending question and the turnId that answers it.
+            // Ticket polling and session status, open to every role READ is open to except a
+            // collaborator: ticket ids are a sequential counter with no owner check, so a holder
+            // could walk every ticket and read another session's delegation reply.
             case TASK_READ -> caller.isPrimary() || caller.isWorker() || caller.isArchitect();
 
             // fleetd #421: reading held lead-to-lead mail is the primary's alone. An architect
             // holds READ today (CB-548), so "not primary" must mean not-architect here too — this
-            // is coordination between leads, not observation of the roster.
+            // is coordination between leads, not observation of the roster. The same reasoning
+            // excludes a collaborator.
             case COORD_READ -> caller.isPrimary();
         };
     }

fleetd/src/main/java/dev/ltms/fleet/auth/Principal.java

@@ -11,7 +11,9 @@ package dev.ltms.fleet.auth;
  * @param pid      the connecting process id, or {@code -1} when not resolvable (audit context)
  * @param name     for a lead resolved from the CB-530 {@code leaders:} registry, which lead it is;
  *                 for an architect resolved from the CB-548 {@code architects:} registry, which
- *                 slot it occupies; {@code null} for every other caller, including an unnamed primary
+ *                 slot it occupies; for a collaborator resolved from the {@code collaborators:}
+ *                 registry, which collaborator it is; {@code null} for every other caller,
+ *                 including an unnamed primary
  */
 public record Principal(Role role, String terminal, long pid, String name) {
 
@@ -73,6 +75,19 @@ public record Principal(Role role, String terminal, long pid, String name) {
         return new Principal(Role.ARCHITECT, terminal, pid, slotName);
     }
 
+    /**
+     * A collaborator: a human-opened tab recognised by its exact label in the
+     * {@code collaborators:} registry.
+     *
+     * <p>Carries {@link Role#COLLABORATOR}. {@code name} is reporting only — it lets
+     * {@code fleet_whoami} say which collaborator is asking. Identity is the {@code terminal}:
+     * like a worker's it comes from the connection, so {@code ownsSession} works exactly as it
+     * does for a worker — a collaborator acts as its own pane and no other.
+     */
+    public static Principal collaborator(String name, String terminal, long pid) {
+        return new Principal(Role.COLLABORATOR, terminal, pid, name);
+    }
+
     public boolean isPrimary() {
         return role == Role.PRIMARY;
     }
@@ -81,6 +96,10 @@ public record Principal(Role role, String terminal, long pid, String name) {
         return role == Role.ARCHITECT;
     }
 
+    public boolean isCollaborator() {
+        return role == Role.COLLABORATOR;
+    }
+
     public boolean isWorker() {
         return role == Role.WORKER;
     }
@@ -120,6 +139,7 @@ public record Principal(Role role, String terminal, long pid, String name) {
         return switch (role) {
             case WORKER -> "worker:" + terminal;
             case ARCHITECT -> "architect:" + name;
+            case COLLABORATOR -> "collaborator:" + name;
             case PRIMARY -> name == null ? "primary" : "leader:" + name;
             case ANONYMOUS -> "anonymous";
         };

fleetd/src/main/java/dev/ltms/fleet/auth/Role.java

@@ -34,6 +34,17 @@ public enum Role {
      */
     ARCHITECT,
 
+    /**
+     * A config-declared, human-opened tab recognised by its exact label (the {@code
+     * fleet.collaborators.<name>.tab} registry). Never spawned — identity comes from the
+     * connection, never a request argument, exactly like {@link #WORKER} and {@link #ARCHITECT}.
+     * May {@code SEND} only to a configured lead or collaborator, {@code REPLY}/{@code ASK} only
+     * as its own pane, and {@code READ}/{@code METRICS}; may not {@code SPAWN}/{@code STOP}/
+     * {@code DRAIN}/{@code HANDOVER}, poll a ticket ({@code TASK_READ}), or reach the
+     * coordination broker ({@code COORD_SEND}/{@code COORD_READ}).
+     */
+    COLLABORATOR,
+
     /** Authenticated as nothing. Authorized for nothing but {@code /healthz}. */
     ANONYMOUS
 }

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

@@ -689,7 +689,7 @@ public final class FleetMcp {
         if (!authorizationEnforced) {
             return null; // AuthorizationMode.UNENFORCED: authorization not enforced (fleetd #518)
         }
-        if (Authz.permits(caller, action, target)) {
+        if (Authz.permits(caller, action, target, Authz.NO_KNOWN_LEAD_OR_COLLABORATOR)) {
             if (action != Authz.Action.READ && action != Authz.Action.TASK_READ) {
                 AuditLog.allowed(caller, action, target); // reads would drown the trail
             }
@@ -1309,6 +1309,18 @@ public final class FleetMcp {
             }
             return text(json(m));
         }
+        if (caller.isCollaborator()) {
+            // A collaborator's name is its slot in the collaborators: registry; sessionId is its
+            // pane so a peer knows where to reach it. No leader key: a collaborator is not a
+            // primary for authorization, unlike a lead.
+            if (caller.name() != null) {
+                m.put("collaborator", caller.name());
+            }
+            if (caller.terminal() != null) {
+                m.put("sessionId", caller.terminal());
+            }
+            return text(json(m));
+        }
         if (!caller.isWorker()) {
             // CB-530: which lead, once more than one pane is configured as one. `role` deliberately
             // still reads "primary" — the fallback ladder in CLAUDE.md keys on it, and a lead IS a

fleetd/src/main/java/dev/ltms/fleet/rest/FleetApp.java

@@ -266,6 +266,17 @@ public final class FleetApp {
         return app;
     }
 
+    /**
+     * The authorization decision behind {@link #allow}, taking the caller directly rather than
+     * pulling it from a servlet {@link Context} — unit-testable without fabricating a live
+     * request, the same reason {@code FleetMcp#denyFor} is split from {@code FleetMcp#deny}. The
+     * classifier is the same shared instance {@link #allow} would use, so a test calling this
+     * exercises the real production gate, not a test-supplied stand-in.
+     */
+    static boolean permitsFor(Principal caller, Authz.Action action, String target) {
+        return Authz.permits(caller, action, target, Authz.NO_KNOWN_LEAD_OR_COLLABORATOR);
+    }
+
     /**
      * Gate a handler on the CB-505 authorization table. Returns {@code true} when the request may
      * proceed; otherwise writes the error response and returns {@code false}.
@@ -279,7 +290,7 @@ public final class FleetApp {
             return true; // legacy: authorization not enforced
         }
         Principal caller = ctx.attribute(CALLER);
-        if (Authz.permits(caller, action, target)) {
+        if (permitsFor(caller, action, target)) {
             if (action != Authz.Action.READ && action != Authz.Action.METRICS
                     && action != Authz.Action.TASK_READ) {
                 AuditLog.allowed(caller, action, target); // reads would drown the trail

fleetd/src/test/java/dev/ltms/fleet/auth/AuthzTest.java

@@ -14,6 +14,7 @@ class AuthzTest {
     private static final Principal ANON = Principal.anonymous();
     private static final Principal ARCH_DESIGN = Principal.architect("lead-designer", "term_design", 400);
     private static final Principal ARCH_OTHER = Principal.architect("reviewer", "term_review", 500);
+    private static final Principal COLLABORATOR = Principal.collaborator("ops", "term_collab", 600);
 
     @Test
     void anonymousIsAuthorizedForNothing() {
@@ -166,4 +167,87 @@ class AuthzTest {
         assertFalse(Authz.isUnauthenticated(WORKER_A));
         assertFalse(Authz.isUnauthenticated(PRIMARY));
     }
+
+    // ── the collaborator matrix ─────────────────────────────────────────────────────────────────
+
+    /**
+     * {@code SEND} for a collaborator is the one grant that is conditional rather than fixed:
+     * flipping only the classifier's answer for the target flips only this outcome.
+     */
+    @Test
+    void aCollaboratorMaySendOnlyWhenTheClassifierAcceptsTheTarget() {
+        assertTrue(Authz.permits(COLLABORATOR, SEND, "term_lead", target -> true),
+                "the classifier accepting the target must grant SEND");
+        assertFalse(Authz.permits(COLLABORATOR, SEND, "term_lead", target -> false),
+                "the classifier refusing the target must deny SEND");
+        assertFalse(Authz.permits(COLLABORATOR, SEND, "term_lead"),
+                "the real production classifier recognises no terminal yet, so SEND is refused today");
+    }
+
+    /**
+     * Control for the test above: every other action's result for a collaborator does not move
+     * when the classifier does. Only {@code SEND} is wired to it.
+     */
+    @Test
+    void theClassifierMovesOnlySendForACollaborator() {
+        for (Authz.Action a : Authz.Action.values()) {
+            if (a == SEND) {
+                continue;
+            }
+            assertEquals(
+                    Authz.permits(COLLABORATOR, a, "term_lead"),
+                    Authz.permits(COLLABORATOR, a, "term_lead", target -> true),
+                    a + " must not depend on the classifier at all");
+        }
+    }
+
+    @Test
+    void aCollaboratorMayReadAndScrapeMetrics() {
+        assertTrue(Authz.permits(COLLABORATOR, READ, null));
+        assertTrue(Authz.permits(COLLABORATOR, METRICS, null));
+    }
+
+    @Test
+    void aCollaboratorMayReplyAndAskOnlyAsItsOwnPane() {
+        assertTrue(Authz.permits(COLLABORATOR, REPLY, "term_collab"),
+                "its own pane is its own");
+        assertTrue(Authz.permits(COLLABORATOR, ASK, "term_collab"));
+
+        assertFalse(Authz.permits(COLLABORATOR, REPLY, "term_design"),
+                "a collaborator must not reply on another pane");
+        assertFalse(Authz.permits(COLLABORATOR, REPLY, null),
+                "an absent target must not pass the own-session rule");
+    }
+
+    /**
+     * Every action denied to a collaborator, asserted denied even when the classifier would
+     * accept any target — proving none of these is actually gated on the classifier at all.
+     */
+    @Test
+    void aCollaboratorIsDeniedLifecycleCoordinationAndTicketPolling() {
+        for (Authz.Action a : new Authz.Action[]{SPAWN, STOP, DRAIN, HANDOVER, ANSWER, COORD_SEND,
+                COORD_READ, TASK_READ}) {
+            assertFalse(Authz.permits(COLLABORATOR, a, "term_lead", target -> true),
+                    "a collaborator must not " + a + " even when the classifier accepts every target");
+        }
+    }
+
+    @Test
+    void aCollaboratorIsNotCountedAsPrimaryWorkerOrArchitect() {
+        assertFalse(COLLABORATOR.isPrimary());
+        assertFalse(COLLABORATOR.isWorker());
+        assertFalse(COLLABORATOR.isArchitect());
+        assertTrue(COLLABORATOR.isCollaborator());
+    }
+
+    /**
+     * A collaborator is never spawned, so it must not be enrolled in the presence map as an
+     * available member. Control: both a worker and an architect — which ARE spawned — still are.
+     */
+    @Test
+    void isSpawnedMemberIsFalseForACollaboratorButTrueForAWorkerAndAnArchitect() {
+        assertFalse(COLLABORATOR.isSpawnedMember());
+        assertTrue(WORKER_A.isSpawnedMember());
+        assertTrue(ARCH_DESIGN.isSpawnedMember());
+    }
 }

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

@@ -97,6 +97,7 @@ class FleetMcpAuthzTest {
     private static final Principal WORKER_A = Principal.worker("term_a", 200);
     private static final Principal ANON = Principal.anonymous();
     private static final Principal ARCH_DESIGN = Principal.architect("lead-designer", "term_design", 400);
+    private static final Principal COLLABORATOR = Principal.collaborator("ops", "term_collab", 600);
 
     // --- the table, enforced on THIS path too ---------------------------------------------------
 
@@ -226,6 +227,19 @@ class FleetMcpAuthzTest {
                 "the caller IS authenticated — it is just not the right role");
     }
 
+    /**
+     * {@code denyFor} passes the real production classifier, not a test-supplied one — no
+     * terminal is recognised as a configured lead or collaborator, so a collaborator's SEND is
+     * refused over MCP.
+     */
+    @Test
+    void aCollaboratorMayNotSendOverMcpWithTheRealProductionClassifier() {
+        FleetMcp m = mcp(true);
+        McpSchema.CallToolResult denied = m.denyFor(COLLABORATOR, Authz.Action.SEND, "term_lead");
+        assertNotNull(denied, "no terminal is recognised as a lead or collaborator yet");
+        assertTrue(denied.isError());
+    }
+
     @Test
     void theLegacyConstructorLeavesTheGateOpen() {
         // The 22 pre-existing FleetMcpTest cases rely on no authorization being enforced.

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

@@ -1837,6 +1837,32 @@ class FleetMcpTest {
         assertTrue(out.contains("\"sessionId\":\"term_design\""), out);
     }
 
+    /**
+     * A collaborator reports its own role and name, never the {@code leader} key a lead gets —
+     * {@code role} already reads {@code "collaborator"}, so a {@code leader} key alongside it
+     * would be self-contradicting. Control: the same call shape fed a named lead must still carry
+     * {@code leader}, so this is not passing because the key stopped being emitted for everyone.
+     */
+    @Test
+    void whoamiReportsACollaboratorWithNoLeaderKeyButALeadStillGetsOne() {
+        FakeHerdr h = new FakeHerdr();
+        SessionManager sessions = sessionManager(h, "http://gx00.gw:8000", Set.of("gx00.gw"));
+
+        McpSchema.CallToolResult collabRes = FleetMcp.whoami(
+                Principal.collaborator("ops", "term_collab", 700), sessions);
+        assertNotEquals(Boolean.TRUE, collabRes.isError());
+        String collabOut = textOf(collabRes);
+        assertTrue(collabOut.contains("\"role\":\"collaborator\""), collabOut);
+        assertTrue(collabOut.contains("\"collaborator\":\"ops\""), collabOut);
+        assertTrue(collabOut.contains("\"sessionId\":\"term_collab\""), collabOut);
+        assertFalse(collabOut.contains("leader"), collabOut);
+
+        McpSchema.CallToolResult leadRes = FleetMcp.whoami(
+                Principal.leader("opus", "term_lead", 100), sessions);
+        String leadOut = textOf(leadRes);
+        assertTrue(leadOut.contains("\"leader\":\"opus\""), leadOut);
+    }
+
     /**
      * CB-548: an architect SEND delegates as its own pane (recording the per-target delegation) but
      * must NEVER become the legacy singleton "primary" fallback — the per-target map does not cure

fleetd/src/test/java/dev/ltms/fleet/rest/FleetAppAuthTest.java

@@ -6,6 +6,7 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 import dev.ltms.fleet.auth.CallerResolver;
 import dev.ltms.fleet.auth.Authz;
 import dev.ltms.fleet.auth.MemberRegistry;
+import dev.ltms.fleet.auth.Principal;
 import dev.ltms.fleet.config.FleetConfig;
 import dev.ltms.fleet.guard.SubscriptionGuard;
 import dev.ltms.fleet.herdr.AgentControl;
@@ -202,6 +203,18 @@ class FleetAppAuthTest {
         }
     }
 
+    /**
+     * {@code permitsFor} is the exact decision {@link FleetApp#allow} makes, passing the real
+     * production classifier rather than a test-supplied one — no terminal is recognised as a
+     * configured lead or collaborator, so a collaborator's SEND is refused through the REST gate.
+     */
+    @Test
+    void aCollaboratorMayNotSendOverRestWithTheRealProductionClassifier() {
+        Principal collaborator = Principal.collaborator("ops", "term_collab", 700);
+        assertFalse(FleetApp.permitsFor(collaborator, Authz.Action.SEND, "term_lead"),
+                "no terminal is recognised as a lead or collaborator yet");
+    }
+
     // --- loopback-trust: the caller is the primary -------------------------------------------
 
     @Test