fleetd #711: re-key two pane-tab hazard reasons onto the unregistered-pane condition

Both refusals said a member landing in a lead's or collaborator's
labelled tab would be read back as that identity. CallerResolver
consults the spawned-member roster ahead of every tab map, so a live
registered member is never misread this way. State the real condition
instead: the hazard applies only while the pane is alive and carries
no entry in the spawned-member roster.

CLAUDE.md

@@ -27,10 +27,11 @@ through its `fleet_*` tools. No session addresses a peer, a broker, or the netwo
 **Every role reads this file.** A member runs in a git worktree of this same repo, so it inherits
 this `CLAUDE.md` verbatim, and every rule below is role-conditional.
 
-**Call `fleet_whoami`.** It returns `primary`, `worker`, or `architect`, resolved by the daemon from
-your connection — unforgeable, and the same resolution its authorization gate uses. A worker also
-carries its `sessionId`, `profile`, `worktree` and `branch`; an architect carries the slot name it
-was bound to. Don't infer what you can ask.
+**Call `fleet_whoami`.** It returns `primary`, `worker`, `architect`, or `collaborator`, resolved by
+the daemon from your connection — unforgeable, and the same resolution its authorization gate uses.
+A worker also carries its `sessionId`, `profile`, `worktree` and `branch`; an architect carries the
+slot name it was bound to; a collaborator carries its registry name and its own `sessionId`, and
+**no `leader` key** — a collaborator is a named peer, not a primary. Don't infer what you can ask.
 
 Only if that call is unavailable, fall back to these — each is one-way, so keep reading until one
 fires: the reply charter in your system prompt (*"You are a spawned member in the
@@ -38,12 +39,17 @@ claude-bridge fleet"*) ⇒ **spawned member**; fleet tools prefixed `mcp__fleet_
 member** (the launcher fixes that mount name; a primary's mount is named by whoever wrote its
 `.mcp.json`, so it varies — and a member spawned before CB-632 still says `mcp__bridge__*`); `ANTHROPIC_BASE_URL` set ⇒ **spawned member** (Claude-model members run
 on a clean env, so its *absence* proves nothing). None of these separate a worker from an architect —
-only `fleet_whoami` does. **Still unsure ⇒ act as a worker**, the most restricted member role. The
+only `fleet_whoami` does. **And none of them fires for a collaborator at all**: every signal in the
+ladder detects a *spawned* member, while a collaborator is a tab a person opened by hand, so it has
+no charter, no fixed mount name and a normal environment. A collaborator that cannot call
+`fleet_whoami` therefore falls to the line below and acts as a worker. That is the safe direction —
+it under-privileges, and the refusals are loud — but it means a collaborator has no way to learn
+what it is except by asking. **Still unsure ⇒ act as a worker**, the most restricted member role. The
 two mistakes are not symmetric: a primary acting as a worker is refused by the authorization gate —
 loud and self-correcting — while a member acting as the primary ends its turn with no `fleet_reply`,
 and the sender silently receives nothing. Fail toward the recoverable error.
 
-### Invariants — both roles, no exceptions
+### Invariants — every role, no exceptions
 
 1. **Never set, export, or forward `ANTHROPIC_BASE_URL`** (or `ANTHROPIC_AUTH_TOKEN`). The primary
    stays on subscription; only the bridge puts a member off it, at spawn. Mounting the bridge must
@@ -51,9 +57,10 @@ and the sender silently receives nothing. Fail toward the recoverable error.
 2. **The bridge is the only channel.** Text you print in your terminal reaches nobody — the other
    side cannot see your screen. An answer that isn't in a `fleet_*` call is silently discarded.
 3. **Identity comes from the connection, never an argument.** Workers never pass a target; you
-   cannot act as another session. Spawn/stop/drain are lead-only; **send is lead or architect**;
-   reply/ask are only-as-itself — any peer may answer for its own pane, and for no other. A call
-   outside your role is refused, not queued.
+   cannot act as another session. Spawn/stop/drain are lead-only; **send is lead, architect, or
+   collaborator** — and a collaborator may send only to a lead or another collaborator, never to a
+   spawned member's terminal; reply/ask are only-as-itself — any peer may answer for its own pane,
+   and for no other. A call outside your role is refused, not queued.
 4. **Delivery is status-gated: one message per turn.** Don't busy-poll a peer's terminal and don't
    re-send because a call looks slow — the bridge delivers when the peer is `idle`, `blocked` or
    `done`. A spawned member must **also** have mounted the bridge MCP: until it has, it is not
@@ -161,6 +168,7 @@ you decide.
 | Answer a member's `fleet_ask` | `fleet_send{turnId, content}` — **not** `sessionId` |
 | Message a **peer lead** on this host | `fleet_send{sessionId: <their terminal>, content}` — `fleet_list` → `leads` reports it. Coordination only, **never** a task |
 | Message a **peer lead** on another daemon or host | `fleet_send{coordId: <their coord-id>, content}` — needs a `coordinator:` block; your own coord-id is in `fleet_list`. Coordination only, **never** a task |
+| Message a **collaborator** on this host | `fleet_send{sessionId: <their terminal>, content}` — but **`fleet_list` does not report collaborators**, so you cannot discover one: it must tell you its `sessionId`, which its own `fleet_whoami` gives it. Coordination only, **never** a task |
 | Answer a peer lead that messaged you | `fleet_send{coordId}` — or `{sessionId}` if they are on this host. **Not** `fleet_reply`: it has no peer route and the publish is refused |
 | Read your own held lead-to-lead mail (no ack) | `fleet_poll{coordId: <your own coord-id, from fleet_list's coordinator.selfId>}` — primary-only; never acks, so `fleet_list`'s `held[]` still shows it after. `fleet_list`'s `held[]` gives only a truncated preview — this is the only way to read the full body |
 | Collect a held reply | `fleet_poll{target}` · then `fleet_ack{target, msgId}` |
@@ -234,6 +242,27 @@ simply complies has thrown away the reason there are two of you.
 7. **Never merge.** Stage files explicitly — never `git add -A` — and leave alone anything the
    project marks as not-yours-to-commit.
 
+### Collaborator — a named peer, not a member
+
+`fleet_whoami` answered `collaborator`, so your pane's tab matches a `fleet.collaborators.<name>.tab`
+entry. You are **not** a member: nothing delegates to you, you have no brief, no worktree and no
+ticket, and **you owe no `fleet_reply`** — the turn contract above is for a session a lead spawned,
+and it does not apply to you. Read it only to understand what the members around you are doing.
+
+What you may do: observe the fleet (`fleet_list`, `fleet_profiles`, `fleet_whoami`), and send to a
+lead or to another collaborator. What you may not: spawn, stop or drain anything, roll a lead's
+session, answer a member's `fleet_ask`, poll a ticket, or send to a spawned member's terminal. Each
+of those is refused at the gate, not queued.
+
+Two limits worth knowing before you hit them. **You cannot reach a worker** — not even to help one —
+because a worker belongs to the lead that spawned it, and routing around that would make you a
+second orchestrator with no plan. Send to the lead instead. And **you cannot read a ticket**, so you
+cannot collect a delegation's reply; ticket ids are a plain counter with no owner check, so holding
+one would let you walk every other session's answers.
+
+Being named buys you a channel, not authority. Your `fleet_send` to a lead is coordination between
+peers: the lead owes you no obedience, and you owe it none.
+
 ### Where each rule lives (don't duplicate — extend the right layer)
 
 | Layer | Scope | Reaches |
@@ -359,7 +388,7 @@ Before you call any work done, check the row that matches what you touched:
 | `ConnectionIdentity` / how a caller is resolved | the `fleet_whoami` paragraph and the fallback ladder |
 | `REPLY_CHARTER`, or a launcher's mount/flags | the fallback ladder (`mcp__fleet__*`), and the layering table's top row |
 | the injector / status gating | invariant 4 |
-| worktree provisioning or the parity overlay | the "both roles read this file" premise — it rests on the worker's worktree being a checkout of this repo |
+| worktree provisioning or the parity overlay | the "every role reads this file" premise — it rests on the worker's worktree being a checkout of this repo |
 | `.claude/skills/**` | the addendum's skill list, and the "name the playbook" rule |
 | a new peer kind (non-Claude adapter) | what that peer can read — anything it must obey belongs in its charter, not in the block |
 | **anything an operator can use, configure, or observe** — an MCP tool, a `fleetd.yaml` knob, an endpoint, a visible behaviour | **[Features](wiki/11-Features.md)** — one entry: what it does · the knob that turns it on · **why it exists** · the gotcha |

fleetd/fleetd.example.yaml

@@ -62,11 +62,12 @@ bind:
 #
 # Leads are configured under `fleet.leaders:` — see THE FLEET further down.
 #
-# Two things stop the tab-name convention from becoming a way to claim leadership: the configured
-# member spaces are excluded from the scan, so nothing fleetd places can land in a matching tab;
-# and startup REFUSES a `tabPrefix` that the fleet tabLabel template, or any per-profile `tabLabel`
-# override, also matches — so the two namespaces cannot overlap by accident. The label is a NAME,
-# never a capability: what a pane may do is decided by the role the daemon resolves for it.
+# Two things stop the tab-name convention from becoming a way to claim leadership: startup REFUSES
+# a `tabPrefix` that the fleet tabLabel template, or any per-profile `tabLabel` override, also
+# matches, so the two namespaces cannot overlap by accident; and the CallerResolver asks the live
+# spawned-member roster BEFORE any tab map, so a live member is never mistaken for a lead no matter
+# what its tab says. The label is a NAME, never a capability: what a pane may do is decided by the
+# role the daemon resolves for it.
 
 # CB-551: IDLE-LEAD HEARTBEAT — nudge the single lead back to work when it has been continuously
 # idle (no open fleet_send driving it) past the quiet period. The fleet is one lead + architects +
@@ -659,9 +660,10 @@ fleet:
   #     tabPrefix: "lead:"           # only used to guard against a worker tabLabel colliding with
   #                                  # this convention at startup; plays no part in matching a lead
   #     scanIntervalSeconds: 10      # rescan cadence, and the worst case before a new tab is seen
-  #     workspace: leads             # where a launched lead's tab is created (default "leads").
-  #                                  # MUST NOT be a member workspace — those are excluded from the
-  #                                  # scan, so a lead placed in one is never found again.
+  #     workspace: leads             # where a launched lead's tab is created (default "fleet",
+  #                                  # the same shared space the members use). Sharing that space
+  #                                  # with members is the normal shipped shape: the scanner tells
+  #                                  # a lead from a member by the exact tab label, not by workspace.
   #     cwd: /path/to/repo           # the launched lead's working directory (default: fleetd's own)
   #     kind: claude                 # descriptive; reported by fleet_whoami
   #   gpt-sol-5.6:
@@ -669,6 +671,22 @@ fleet:
   #     kind: opencode
   #     model: openai/gpt-5.6-terra
 
+  # A collaborator tab, keyed by name (fleetd #669). A pane whose tab matches resolves as the
+  # COLLABORATOR role: `fleet_whoami` answers `collaborator`, and the session may observe the fleet
+  # (`fleet_list`, `fleet_profiles`, `fleet_whoami`) and `fleet_send` to a lead or to another
+  # collaborator. It may NOT spawn, stop or drain anything, roll a lead's session, answer a
+  # member's `fleet_ask`, poll a ticket, send across hosts, or send to a spawned member's terminal.
+  # Each of those is refused at the gate rather than queued.
+  # Recognise-only, like a profile-less `leaders:` entry above: there is no `profile:`, no
+  # `instances:` and no `kind:`. `tab:` is REQUIRED and is the only field identity depends on,
+  # matched case-insensitively — the same GET-THE-VALUE-RIGHT warning above the `leaders:` block
+  # applies here too.
+  # A lead cannot discover a collaborator yet (#703): `fleet_list` has no `collaborators` key, so
+  # the collaborator must speak first, or pass on the `sessionId` its own `fleet_whoami` reports.
+  # collaborators:
+  #   reviewer-alex:
+  #     tab: "collab: alex"
+
   # architects:
   #   architect-1:
   #     profile: opus                # a strong model, on the operator's subscription

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

@@ -217,25 +217,28 @@ public final class Fleetd {
 
     /**
      * The {@link Injector}'s readiness gate (CB-534): a target is deliverable if it is a spawned
-     * member whose agent has connected the bridge MCP, <em>or</em> a lead.
+     * member whose agent has connected the bridge MCP, a lead, <em>or</em> a collaborator.
      *
      * <p>The gate exists for one reason — to hold a delivery out of a <em>spawned</em> member's boot
      * window, where herdr already reports {@code idle} but the TUI would drop an injected paste. That
      * hazard is a property of spawning. A lead is never spawned: the operator started it and named it
-     * (or labelled its tab) only once it was up, so there is no boot window to guard.
+     * (or labelled its tab) only once it was up, so there is no boot window to guard. A collaborator
+     * is the same way — a person's own tab, matched to a configured name, never spawned.
      *
-     * <p>A lead is also never enrolled in {@link MemberPresence} — {@code FleetMcp} marks presence
-     * for every spawned member (worker and architect), deliberately, since that map doubles as the
-     * member roster's availability signal and a lead counted there would show up as an available
-     * member. So without the second disjunct a lead is permanently un-deliverable: every
-     * lead→lead send sat on the gate for {@code READINESS_GRACE_POLLS} (~60s) and then failed
-     * having never been typed into the pane.
+     * <p>Neither a lead nor a collaborator is ever enrolled in {@link MemberPresence} — {@code
+     * FleetMcp} marks presence for every spawned member (worker and architect), deliberately, since
+     * that map doubles as the member roster's availability signal and a lead or collaborator counted
+     * there would show up as an available member. So without the second and third disjuncts a lead or
+     * collaborator is permanently un-deliverable: every send to one sat on the gate for
+     * {@code READINESS_GRACE_POLLS} (~60s) and then failed having never been typed into the pane.
      *
-     * <p>The lead set is read through the supplier on each call rather than snapshotted, so a lead
-     * discovered by {@code leadScan} after startup becomes deliverable without a restart.
+     * <p>Both sets are read through their supplier on each call rather than snapshotted, so a lead or
+     * collaborator discovered by {@code leadScan} after startup becomes deliverable without a restart.
      */
-    static Predicate<String> deliverableTo(MemberPresence presence, Supplier<Map<String, String>> leads) {
-        return target -> presence.isPresent(target) || leads.get().containsKey(target);
+    static Predicate<String> deliverableTo(MemberPresence presence, Supplier<Map<String, String>> leads,
+            Supplier<Map<String, String>> collaborators) {
+        return target -> presence.isPresent(target) || leads.get().containsKey(target)
+                || collaborators.get().containsKey(target);
     }
 
     /**

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

@@ -43,6 +43,7 @@ import dev.ltms.fleet.msg.MessageService;
 import dev.ltms.fleet.msg.Rendezvous;
 import dev.ltms.fleet.msg.ReplyInbox;
 import dev.ltms.fleet.msg.ReplyPushLoop;
+import dev.ltms.fleet.peer.MemberRole;
 import dev.ltms.fleet.peer.PeerLauncher;
 import dev.ltms.fleet.placement.BackendOutagePolicy;
 import dev.ltms.fleet.placement.BackendQuarantine;
@@ -50,6 +51,7 @@ import dev.ltms.fleet.power.CaffeinateSleepAssertionMechanism;
 import dev.ltms.fleet.power.IdleSleepGuard;
 import dev.ltms.fleet.rest.FleetApp;
 import dev.ltms.fleet.session.GitWorktrees;
+import dev.ltms.fleet.session.MemberSession;
 import dev.ltms.fleet.session.SessionManager;
 import dev.ltms.fleet.session.SessionReaper;
 import io.javalin.Javalin;
@@ -141,8 +143,12 @@ final class FleetdAssembly {
                 ? ports.connectHerdr(Path.of(cfg.memberHerdrSocket()))
                 : herdr;
         AtomicReference<Supplier<Map<String, String>>> leadsRef = new AtomicReference<>(Map::of);
+        // fleetd #669 Unit E: a collaborator's pane is opened by a person, exactly like a lead's,
+        // so its terminal must also route to the lead herdr daemon rather than the member one.
+        AtomicReference<Supplier<Map<String, String>>> collaboratorTerminalsRef = new AtomicReference<>(Map::of);
         HerdrRouter router = new HerdrRouter(herdr, memberHerdr,
-                target -> leadsRef.get().get().containsKey(target));
+                target -> leadsRef.get().get().containsKey(target)
+                        || collaboratorTerminalsRef.get().get().containsKey(target));
         // CB-402: one adapter per configured peer kind, fronted by a composite router. A profile's
         // `kind:` selects its adapter — claude-code (the default) and opencode partition the profile
         // set — and the composite dispatches each SPI call to the adapter that owns the profile/pane.
@@ -250,26 +256,47 @@ final class FleetdAssembly {
             log.info("leads: {} panes recognised {}", leadTerminals.size(), leadTerminals.values());
         }
         // CB-531/CB-579: discover leads by the tab labels the operator writes, one scanner per
-        // configured lead's own exact `tab:` label.
+        // configured lead's own exact `tab:` label. fleetd #669: the same scan also recognises a
+        // configured collaborator's tab, so one herdr pass answers both.
         final Supplier<Map<String, String>> leads;
+        final Supplier<Map<String, String>> collaboratorTerminals;
         var leaders = cfg.fleet().leaders();
-        if (!leaders.isEmpty()) {
+        var collaboratorsConfig = cfg.fleet().collaborators();
+        if (!leaders.isEmpty() || !collaboratorsConfig.isEmpty()) {
             Map<String, String> tabToName = new LinkedHashMap<>();
             leaders.forEach((name, leader) -> {
                 if (leader != null && leader.tab() != null && !leader.tab().isBlank()) {
                     tabToName.put(leader.tab(), name);
                 }
             });
-            int scanIntervalSeconds = leaders.values().iterator().next().scanIntervalSeconds();
+            Map<String, String> collaboratorTabToName = new LinkedHashMap<>();
+            collaboratorsConfig.forEach((name, collaborator) -> {
+                if (collaborator != null && collaborator.tab() != null && !collaborator.tab().isBlank()) {
+                    collaboratorTabToName.put(collaborator.tab(), name);
+                }
+            });
+            // A collaborator-only fleet configures no `leaders:` entry to read a scan interval from
+            // — FleetConfig.Collaborator carries no scanIntervalSeconds of its own. Falling back to
+            // FleetConfig.Leader's own compact-constructor default keeps a collaborator-only
+            // deployment on the same rescan cadence as the default lead cadence, instead of
+            // inventing a second number for the same kind of scan.
+            int scanIntervalSeconds = leaders.isEmpty()
+                    ? 10
+                    : leaders.values().iterator().next().scanIntervalSeconds();
             // This must use the lead daemon: scanning member tabs would demote the lead to a worker.
-            leads = new LeadTabScanner(herdr, tabToName, Set.of(),
+            LeadTabScanner scanner = new LeadTabScanner(herdr, tabToName, collaboratorTabToName, Set.of(),
                     TimeUnit.SECONDS.toNanos(scanIntervalSeconds), ports.nanoClock());
-            log.info("lead scan: tabs {} host a lead (rescan every {}s, shared fleet space)",
-                    tabToName.keySet(), scanIntervalSeconds);
+            leads = scanner;
+            collaboratorTerminals = scanner::collaborators;
+            log.info("lead/collaborator scan: tabs {} host a lead, tabs {} host a collaborator "
+                            + "(rescan every {}s, shared fleet space)",
+                    tabToName.keySet(), collaboratorTabToName.keySet(), scanIntervalSeconds);
         } else {
             leads = () -> leadTerminals;
+            collaboratorTerminals = Map::of;
         }
         leadsRef.set(leads);
+        collaboratorTerminalsRef.set(collaboratorTerminals);
 
         // CB-558: start any declared lead that is not already running. After the scanner is built,
         // and only when herdr answered — the launcher's whole safety property is that it can count
@@ -341,7 +368,7 @@ final class FleetdAssembly {
         // CB-301: the manager's presence bridge records availability and drives SPAWNING → READY.
         MemberPresence presence = sessions.asPresence();
         TurnListener turnListener = Fleetd.turnListener(completion, sessions);
-        Predicate<String> deliverable = Fleetd.deliverableTo(presence, leads);
+        Predicate<String> deliverable = Fleetd.deliverableTo(presence, leads, collaboratorTerminals);
         // fleetd #556: registration is wired directly to `completion`, not folded into the
         // `turnListener` fan-out above — so it survives `sessions.onDelivered` (or any future
         // listener) throwing, regardless of call order.
@@ -452,6 +479,15 @@ final class FleetdAssembly {
         ConnectionIdentity identity = new ConnectionIdentity(
                 new PaneLocator(herdr, memberHerdr), new LsofPeerPidLookup(), new LsofProcessCwdLookup());
 
+        // fleetd #669 Unit D: a live spawned member resolves as its own role, whatever a tab map
+        // says about the same terminal — read from the roster meant for a hot path (SessionManager
+        // javadoc), never rosterResolved(), since resolve() runs on every request.
+        Function<String, MemberRole> spawnedMemberRole = terminal -> sessions.roster().stream()
+                .filter(s -> terminal.equals(s.terminalId()))
+                .map(MemberSession::role)
+                .findFirst()
+                .orElse(null);
+
         // CB-501: one resolver behind both entry paths. Worker identity still comes from the
         // connection and is never token-gated, so enabling token mode cannot lock the fleet out.
         final CallerResolver callers;
@@ -461,11 +497,13 @@ final class FleetdAssembly {
                 throw new IllegalStateException("auth.mode=token but env var " + cfg.auth().tokenEnv()
                         + " is unset or empty — export it before starting fleetd");
             }
-            callers = CallerResolver.withLeadsAndMembers(identity, true, token, leads, members);
+            callers = CallerResolver.withLeadsAndMembers(identity, true, token, leads, members,
+                    spawnedMemberRole, collaboratorTerminals);
             log.info("auth: token mode (bearer required for non-worker callers, env {})",
                     cfg.auth().tokenEnv());
         } else {
-            callers = CallerResolver.withLeadsAndMembers(identity, false, null, leads, members);
+            callers = CallerResolver.withLeadsAndMembers(identity, false, null, leads, members,
+                    spawnedMemberRole, collaboratorTerminals);
             log.info("auth: loopback-trust (any loopback non-worker caller is the primary)");
         }
 

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}
+     * The fail-closed classifier: answers no for every target, so a collaborator's {@code SEND}
+     * is refused unless a caller supplies a real one. {@code CallerResolver#knownLeadOrCollaborator()}
+     * is the real one, read from the same lead and collaborator maps {@code CallerResolver#resolve}
+     * consults, so a target that classifier calls known is one {@code resolve} would actually
+     * resolve as a lead or collaborator.
+     */
+    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/CallerResolver.java

@@ -7,6 +7,7 @@ import java.nio.charset.StandardCharsets;
 import java.security.MessageDigest;
 import java.util.Map;
 import java.util.function.Function;
+import java.util.function.Predicate;
 import java.util.function.Supplier;
 
 /**
@@ -19,6 +20,13 @@ import java.util.function.Supplier;
  *
  * <p><strong>Resolution order</strong> — connection identity first, token second, nothing third:
  * <ol>
+ *   <li>A loopback peer PID that maps to a pane this gateway itself spawned ⇒ that member's own
+ *       role: {@link Role#WORKER} for a dev, hunter, or reviewer; {@link Role#ARCHITECT} for an
+ *       architect, but only while the live slot role still confirms it (fleetd #424 — a slot
+ *       revoked from config demotes an already-bound session on its very next request, so the
+ *       roster's own role is never granted on its word alone). No tab map is consulted — a live
+ *       spawned member's identity comes from the registry that spawned it, never from a label a
+ *       pane could also carry.</li>
  *   <li>A loopback peer PID that maps to a pane named by {@code leaders:}, by the legacy
  *       {@code primary.terminal} pin, or by an operator-labelled lead tab (CB-307, CB-530, CB-531)
  *       ⇒ {@link Role#PRIMARY}, carrying that lead's
@@ -28,8 +36,10 @@ import java.util.function.Supplier;
  *       so two leads can work as peers rather than one being demoted.</li>
  *   <li>A loopback peer PID that maps to a pane bound to a CB-548 architect slot ⇒
  *       {@link Role#ARCHITECT}, carrying the slot name. Just unforgeable as a worker's, and
- *       resolved from the <em>live</em> terminal→slot binding (never a request argument), before
- *       the generic worker fallback.</li>
+ *       resolved from the <em>live</em> terminal→slot binding (never a request argument). This is
+ *       the case the previous step does not catch: a binding with no live spawned-member session.</li>
+ *   <li>A loopback peer PID that maps to an operator-labelled collaborator tab ⇒
+ *       {@link Role#COLLABORATOR}, carrying that collaborator's name.</li>
  *   <li>A loopback peer PID that maps to any other herdr pane ⇒ {@link Role#WORKER}. This is
  *       unforgeable (the OS reports the PID, herdr owns the PID→pane map) and is honoured
  *       regardless of auth mode, so enabling auth never breaks the fleet.</li>
@@ -64,6 +74,20 @@ public final class CallerResolver {
     private final Supplier<Map<String, String>> architectTerminals;
     private final Function<String, MemberRole> memberSlotRoles;
     private final Function<String, String> memberSlotNames;
+    /**
+     * terminal_id → the role of the live spawned member occupying it, or {@code null} for a
+     * terminal no spawned member occupies. Consulted first, ahead of every tab map: a live
+     * spawned member's identity is its own, whatever a tab map says about the same terminal.
+     * A function rather than the roster itself, so a resolve on the hot path never scans a list —
+     * the lookup strategy is the caller's to choose.
+     */
+    private final Function<String, MemberRole> spawnedMemberRole;
+    /**
+     * terminal_id → collaborator name; empty when none are configured. A supplier for the same
+     * reason as {@link #leadTerminals}: a collaborator tab recognised after construction (the tab
+     * scan discovering a newly-labelled tab) takes effect without a restart.
+     */
+    private final Supplier<Map<String, String>> collaboratorTerminals;
 
     /** Loopback-trust resolver: no token required, historical behaviour. Test-only. */
     CallerResolver(ConnectionIdentity identity) {
@@ -124,17 +148,42 @@ public final class CallerResolver {
     /**
      * Live registry form that can confirm a bound slot is an architect slot.
      *
-     * <p>This is the only public construction path. It keeps terminal bindings and slot roles in
-     * the same {@link MemberRegistry}, so a configured architect can resolve as an architect.
+     * <p>It keeps terminal bindings and slot roles in the same {@link MemberRegistry}, so a
+     * configured architect can resolve as an architect. No spawned-member roster or collaborator
+     * registry is consulted — equivalent to {@link #withLeadsAndMembers(ConnectionIdentity,
+     * boolean, String, Supplier, MemberRegistry, Function, Supplier)} with both absent. Kept for
+     * every caller that has neither to offer, so adding them did not churn every construction site.
      */
     public static CallerResolver withLeadsAndMembers(ConnectionIdentity identity,
                                                        boolean tokenMode, String token,
                                                        Supplier<Map<String, String>> leadTerminals,
                                                        MemberRegistry members) {
+        return withLeadsAndMembers(identity, tokenMode, token, leadTerminals, members, null, null);
+    }
+
+    /**
+     * Live registry form that also resolves a live spawned member to its own role, and a
+     * configured collaborator tab to {@link Role#COLLABORATOR}.
+     *
+     * <p>This is the only public construction path that exercises the full resolution order.
+     *
+     * @param spawnedMemberRole      terminal_id → the role of the live spawned member occupying
+     *                               it, or {@code null} for a terminal no spawned member occupies.
+     *                               {@code null} here means no roster is consulted at all (every
+     *                               terminal falls through to the tab maps), not that none matches.
+     * @param collaboratorTerminals  terminal_id → collaborator name, live like {@code leadTerminals}
+     */
+    public static CallerResolver withLeadsAndMembers(ConnectionIdentity identity,
+                                                       boolean tokenMode, String token,
+                                                       Supplier<Map<String, String>> leadTerminals,
+                                                       MemberRegistry members,
+                                                       Function<String, MemberRole> spawnedMemberRole,
+                                                       Supplier<Map<String, String>> collaboratorTerminals) {
         return new CallerResolver(identity, tokenMode, token, leadTerminals,
                 members == null ? null : members::snapshot,
                 members == null ? null : members::roleForSlot,
-                members == null ? null : members::nameForSlot);
+                members == null ? null : members::nameForSlot,
+                spawnedMemberRole, collaboratorTerminals);
     }
 
     private static Supplier<Map<String, String>> fixed(Map<String, String> leadTerminals) {
@@ -160,6 +209,17 @@ public final class CallerResolver {
                            Supplier<Map<String, String>> architectTerminals,
                            Function<String, MemberRole> memberSlotRoles,
                            Function<String, String> memberSlotNames) {
+        this(identity, tokenMode, token, leadTerminals, architectTerminals, memberSlotRoles,
+                memberSlotNames, null, null);
+    }
+
+    private CallerResolver(ConnectionIdentity identity, boolean tokenMode, String token,
+                           Supplier<Map<String, String>> leadTerminals,
+                           Supplier<Map<String, String>> architectTerminals,
+                           Function<String, MemberRole> memberSlotRoles,
+                           Function<String, String> memberSlotNames,
+                           Function<String, MemberRole> spawnedMemberRole,
+                           Supplier<Map<String, String>> collaboratorTerminals) {
         if (tokenMode && (token == null || token.isBlank())) {
             throw new IllegalArgumentException(
                     "auth.mode=token requires a non-empty token; check that the env var named by "
@@ -172,6 +232,8 @@ public final class CallerResolver {
         this.architectTerminals = architectTerminals == null ? Map::of : architectTerminals;
         this.memberSlotRoles = memberSlotRoles == null ? _ -> null : memberSlotRoles;
         this.memberSlotNames = memberSlotNames == null ? Function.identity() : memberSlotNames;
+        this.spawnedMemberRole = spawnedMemberRole == null ? _ -> null : spawnedMemberRole;
+        this.collaboratorTerminals = collaboratorTerminals == null ? Map::of : collaboratorTerminals;
     }
 
     /**
@@ -198,6 +260,27 @@ public final class CallerResolver {
         return architectTerminals.get();
     }
 
+    /**
+     * The currently-recognised collaborator tabs, {@code terminal_id → name}.
+     *
+     * <p>Read from the same supplier {@link #resolve} consults, for the reason given in
+     * {@link #leads()}. Live for the same reason as {@link #leads()}.
+     */
+    public Map<String, String> collaborators() {
+        return collaboratorTerminals.get();
+    }
+
+    /**
+     * Whether {@code target} names a terminal this resolver would resolve as a lead or a
+     * collaborator — the classifier a collaborator's {@code SEND} is checked against, read from the
+     * exact maps {@link #resolve} consults so a target that would resolve as a lead or collaborator
+     * is never the one a collaborator is refused to reach, or the reverse.
+     */
+    public Predicate<String> knownLeadOrCollaborator() {
+        return target -> leadTerminals.get().containsKey(target)
+                || collaboratorTerminals.get().containsKey(target);
+    }
+
     /**
      * Resolve the caller of a request.
      *
@@ -208,6 +291,25 @@ public final class CallerResolver {
     public Principal resolve(String remoteAddr, int remotePort, String authorizationHeader) {
         ConnectionIdentity.Caller c = identity.resolve(remoteAddr, remotePort);
         if (c.terminal() != null) {
+            MemberRole spawnedRole = spawnedMemberRole.apply(c.terminal());
+            if (spawnedRole != null) {
+                // A live spawned member occupies this pane. Its identity is its own, whatever a tab
+                // map says about the same terminal — checked before every tab map, consulting none
+                // of them, so a tab label can never override a roster entry for the same terminal.
+                if (spawnedRole == MemberRole.ARCHITECT) {
+                    // The roster only answers THAT this pane is a live spawned member; config still
+                    // decides WHAT that member's slot grants (fleetd #424). A slot revoked after the
+                    // bind must still demote this session on its very next request, so the roster's
+                    // own ARCHITECT role is confirmed against the live slot role, exactly as the
+                    // architect-slot step below confirms a binding with no live member session.
+                    String slot = architectTerminals.get().get(c.terminal());
+                    if (slot != null && memberSlotRoles.apply(slot) == MemberRole.ARCHITECT) {
+                        return Principal.architect(memberSlotNames.apply(slot), c.terminal(), c.pid());
+                    }
+                    return Principal.worker(c.terminal(), c.pid());
+                }
+                return Principal.worker(c.terminal(), c.pid());
+            }
             String lead = leadTerminals.get().get(c.terminal());
             if (lead != null) {
                 // The config names this pane as a lead's own. The pane mapping is exactly as
@@ -221,10 +323,17 @@ public final class CallerResolver {
                 // The config/live binding names this pane as an architect slot's own. Same
                 // unforgeable pane mapping; the live binding, never a request argument, decides.
                 // Check the slot role too: this defence in depth prevents a bad lifecycle bind from
-                // escalating a dev, hunter or reviewer into an architect. Checked before
-                // the worker fallback.
+                // escalating a dev, hunter or reviewer into an architect. This is the case the
+                // spawned-member step above does not catch: a binding with no live member session.
                 return Principal.architect(memberSlotNames.apply(slot), c.terminal(), c.pid());
             }
+            String collaborator = collaboratorTerminals.get().get(c.terminal());
+            if (collaborator != null) {
+                // An operator-labelled collaborator tab, confirmed live by the same scan that
+                // confirms a lead tab. Checked last among the tab maps so a pane also matching one
+                // of the above keeps that stronger role.
+                return Principal.collaborator(collaborator, c.terminal(), c.pid());
+            }
             return Principal.worker(c.terminal(), c.pid()); // unforgeable; never token-gated
         }
 

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/config/ConfigRef.java

@@ -615,7 +615,7 @@ public final class ConfigRef implements Supplier<FleetConfig> {
         // may bind to, AND what a slot already bound still grants) through its own instance of that
         // same supplier shape — see MemberRegistry.live and its class doc for the binding rule:
         // removing a slot revokes ARCHITECT on the bound pane's very next request, and only the slot
-        // OCCUPANCY survives, so the demoted session keeps its slot key until it unbinds. Only
+        // OCCUPANCY survives, so the demoted session keeps its slot key until it unbinds.
         // fleet.leaders is frozen (Fleetd.java:281 reads cfg.fleet().leaders() off the startup
         // snapshot to build both the LeadTabScanner's tab-label-to-name map, wired into
         // CallerResolver.withLeadsAndMembers at Fleetd.java:620/624, and — when herdr answered —
@@ -635,6 +635,11 @@ public final class ConfigRef implements Supplier<FleetConfig> {
                     + "live through that same supplier for placement AND through a separate supplier "
                     + "on MemberRegistry for spawn-time identity — both already applied");
         }
+        if (!Objects.equals(collaboratorsOf(old), collaboratorsOf(fresh))) {
+            changed.add("fleet: fleet.collaborators (each collaborator's tab) is read once at "
+                    + "startup to build the LeadTabScanner's identity map, which is not rebuilt on "
+                    + "reload, so a collaborator added, removed, or given a new tab: needs a restart");
+        }
         // Kept in step with SPLIT_KEYS the same way changedColdKeys is kept in step with COLD_KEYS —
         // every message here must be traceable to one of the split keys the class doc documents.
         // NOTE what this does NOT prove, per the javadoc above: it does not catch a SPLIT_KEYS
@@ -650,6 +655,11 @@ public final class ConfigRef implements Supplier<FleetConfig> {
         return cfg.fleet() == null ? Map.of() : cfg.fleet().leaders();
     }
 
+    /** {@code cfg.fleet().collaborators()}, defensively, in case a caller hands in a non-defaulted config. */
+    private static Map<String, FleetConfig.Collaborator> collaboratorsOf(FleetConfig cfg) {
+        return cfg.fleet() == null ? Map.of() : cfg.fleet().collaborators();
+    }
+
     /**
      * {@link FleetConfig.Profile} record components deliberately left out of
      * {@link #sameLaunchSettings} because they are read <em>live</em>, not baked in at spawn — see

fleetd/src/main/java/dev/ltms/fleet/config/FleetConfig.java

@@ -1176,6 +1176,25 @@ public record FleetConfig(
         }
     }
 
+    /**
+     * A tab fleetd recognises as a collaborator, keyed by name (fleetd #669).
+     *
+     * <p>Recognise-only: there is no {@code profile}, no {@code instances} and no {@code kind}.
+     * Nothing here ever launches a pane.
+     *
+     * <p>{@code tabPrefix} is absent. Identity is matched on the exact {@code tab} alone.
+     *
+     * @param tab the exact tab label hosting this collaborator, matched case-insensitively; the
+     *            only field identity depends on. Required — an entry with no {@code tab} can
+     *            never be discovered.
+     */
+    @JsonIgnoreProperties(ignoreUnknown = true)
+    public record Collaborator(String tab) {
+        public Collaborator {
+            tab = (tab == null || tab.isBlank()) ? null : tab.strip();
+        }
+    }
+
     /**
      * One entry of a {@code fleet:} role pool — a role paired with the backend it runs on.
      *
@@ -1213,15 +1232,18 @@ public record FleetConfig(
      * is exactly compatible with that. The pool is also what replaced {@code defaultProfile:} — an
      * unqualified spawn names a role, and the role's pool supplies the candidates.
      *
-     * @param leaders     panes that orchestrate rather than are orchestrated, keyed by lead name
-     * @param architects  profiles the {@code architect} role may run on
-     * @param developers  profiles the {@code dev} role may run on
-     * @param hunters     profiles the {@code hunter} role may run on
-     * @param reviewers   profiles the {@code reviewer} role may run on
-     * @param charters    optional launch-charter text keyed by singular role wire name
-     * @param tabLabel    template for a member tab's label; {@code {role}}, {@code {profile}},
-     *                    {@code {model}} and {@code {n}} (a per role+profile counter) are
-     *                    substituted. Default {@link #DEFAULT_TAB_LABEL}
+     * @param leaders       panes that orchestrate rather than are orchestrated, keyed by lead name
+     * @param architects    profiles the {@code architect} role may run on
+     * @param developers    profiles the {@code dev} role may run on
+     * @param hunters       profiles the {@code hunter} role may run on
+     * @param reviewers     profiles the {@code reviewer} role may run on
+     * @param charters      optional launch-charter text keyed by singular role wire name
+     * @param tabLabel      template for a member tab's label; {@code {role}}, {@code {profile}},
+     *                      {@code {model}} and {@code {n}} (a per role+profile counter) are
+     *                      substituted. Default {@link #DEFAULT_TAB_LABEL}
+     * @param collaborators tabs fleetd recognises as collaborators (fleetd #669), keyed by name.
+     *                      Recognise-only, exactly like a {@code profile}-less {@link Leader}:
+     *                      nothing here is ever auto-launched.
      */
     @JsonIgnoreProperties(ignoreUnknown = true)
     public record Fleet(Map<String, Leader> leaders,
@@ -1230,7 +1252,8 @@ public record FleetConfig(
                         Map<String, Slot> hunters,
                         Map<String, Slot> reviewers,
                         Map<String, String> charters,
-                        String tabLabel) {
+                        String tabLabel,
+                        Map<String, Collaborator> collaborators) {
 
         /**
          * Role first, so the tab bar identifies the member's fleet role.
@@ -1245,26 +1268,30 @@ public record FleetConfig(
             reviewers = unmodifiableOrEmpty(reviewers);
             charters = unmodifiableOrEmpty(charters);
             tabLabel = (tabLabel == null || tabLabel.isBlank()) ? DEFAULT_TAB_LABEL : tabLabel;
+            collaborators = unmodifiableOrEmpty(collaborators);
         }
 
         /**
-         * A fleet with no configured launch charters — the shape every deployment had before
-         * CB-566, and what most tests want.
+         * A fleet with no configured launch charters and no collaborators — the shape every
+         * deployment had before CB-566, and what most tests want.
          *
          * <p>Kept deliberately, even though an overload that drops a new field is normally the
          * shape to avoid. It is safe here because nothing <em>reads</em> a charter through a
          * constructor: the launcher reads {@code fleet.charters()} from the live config. Jackson
          * binds the canonical constructor, so this one cannot swallow an operator's YAML.
+         * {@code collaborators} is dropped the same way and for the same reason: no caller of
+         * this overload has ever needed to set it, so it defaults to empty here exactly as the
+         * canonical constructor would default an absent YAML key.
          */
         public Fleet(Map<String, Leader> leaders, Map<String, Slot> architects,
                      Map<String, Slot> developers, Map<String, Slot> reviewers,
                      Map<String, String> charters, String tabLabel) {
-            this(leaders, architects, developers, null, reviewers, charters, tabLabel);
+            this(leaders, architects, developers, null, reviewers, charters, tabLabel, null);
         }
 
         public Fleet(Map<String, Leader> leaders, Map<String, Slot> architects,
                      Map<String, Slot> developers, Map<String, Slot> reviewers, String tabLabel) {
-            this(leaders, architects, developers, null, reviewers, null, tabLabel);
+            this(leaders, architects, developers, null, reviewers, null, tabLabel, null);
         }
 
         /**
@@ -1910,7 +1937,7 @@ public record FleetConfig(
 
     /** The {@code fleet:} child blocks whose direct children are slot names. */
     private static final Set<String> FLEET_POOL_KEYS =
-            Set.of("leaders", "architects", "developers", "hunters", "reviewers");
+            Set.of("leaders", "architects", "developers", "hunters", "reviewers", "collaborators");
 
     /**
      * Reject a {@code fleet:} role pool whose slot names repeat (CB-548, re-homed by CB-557).
@@ -1920,7 +1947,7 @@ public record FleetConfig(
      * daemon would never know. Jackson's YAML parser does not fail on duplicate mapping keys by
      * default, so duplicates are caught here, at parse time, before the map is built.
      *
-     * <p>Only the five pools <em>directly under the top-level {@code fleet:}</em> are considered,
+     * <p>Only the six pools <em>directly under the top-level {@code fleet:}</em> are considered,
      * and only their direct child keys (the slot names). A nested field elsewhere, even one also
      * named {@code developers:}, is ignored, so parsing of the rest of the config is unaffected.
      *
@@ -2679,17 +2706,21 @@ public record FleetConfig(
     }
 
     /**
-     * Reject a member tab-label template that could render as a configured lead tab or match a
-     * lead-tab naming convention, and reject two {@code fleet.leaders} entries that share one exact
-     * tab.
+     * Reject a member tab-label template that could render as a configured lead or collaborator
+     * tab or match a lead-tab naming convention, and reject two {@code fleet.leaders} or
+     * {@code fleet.collaborators} entries — across either registry — that share one exact tab.
+     *
+     * <p>{@code fleet.collaborators} has no {@code tabPrefix}: identity is matched on the exact
+     * {@code tab} alone, so only the exact-render check applies there, not the prefix check.
      *
      * @throws IllegalStateException when the fleet template or a profile {@code tabLabel} override
-     *                               can render as a configured lead tab or match a lead-tab prefix,
-     *                               or when two {@code fleet.leaders} entries carry the same exact
-     *                               {@code tab} (case-insensitively)
+     *                               can render as a configured lead or collaborator tab or match a
+     *                               lead-tab prefix, or when two entries — of either registry, or
+     *                               one of each — carry the same exact {@code tab}
+     *                               (case-insensitively)
      */
     public void validateLeadTabPrefixes() {
-        if (fleet == null || fleet.leaders().isEmpty()) {
+        if (fleet == null) {
             return;
         }
         List<String> bad = new ArrayList<>();
@@ -2722,11 +2753,33 @@ public record FleetConfig(
                         }
                     });
         });
+        fleet.collaborators().forEach((collabName, collaborator) -> {
+            if (collaborator == null) {
+                return;
+            }
+            String tab = collaborator.tab();
+            if (templateCanRenderAs(fleet.tabLabel(), tab)) {
+                bad.add("fleet.tabLabel=\"" + fleet.tabLabel() + "\" can render as the tab of "
+                        + "collaborator '" + collabName + "' (\"" + tab + "\")");
+            }
+            profiles().entrySet().stream()
+                    .map(Map.Entry::getKey)
+                    .sorted()
+                    .forEach(p -> {
+                        String label = profiles().get(p).tabLabel();
+                        if (templateCanRenderAs(label, tab)) {
+                            bad.add("profile '" + p + "' overrides tabLabel with \"" + label
+                                    + "\", which can render as the tab of collaborator '"
+                                    + collabName + "' (\"" + tab + "\")");
+                        }
+                    });
+        });
         if (!bad.isEmpty()) {
             throw new IllegalStateException("refusing to start: " + String.join("; ", bad)
-                    + ". Every member labelled that way would be read back as a lead and granted "
-                    + "spawn/stop/send on the whole fleet. Change one of the two so member tabs "
-                    + "and lead tabs cannot be confused.");
+                    + ". A member labelled that way, while its pane carries no entry in the "
+                    + "spawned-member roster, is read back as a lead or collaborator and granted "
+                    + "that identity's authority. Change one of the two so member tabs cannot be "
+                    + "confused with a lead's or collaborator's tab.");
         }
 
         List<String> collisions = new ArrayList<>();
@@ -2749,13 +2802,49 @@ public record FleetConfig(
                 }
             }
         }
+        List<String> collabNames = fleet.collaborators().keySet().stream().sorted().toList();
+        for (int i = 0; i < collabNames.size(); i++) {
+            String nameA = collabNames.get(i);
+            Collaborator a = fleet.collaborators().get(nameA);
+            if (a == null || a.tab() == null || a.tab().isBlank()) {
+                continue;
+            }
+            for (int j = i + 1; j < collabNames.size(); j++) {
+                String nameB = collabNames.get(j);
+                Collaborator b = fleet.collaborators().get(nameB);
+                if (b == null || b.tab() == null || b.tab().isBlank()) {
+                    continue;
+                }
+                if (a.tab().equalsIgnoreCase(b.tab())) {
+                    collisions.add("collaborator '" + nameA + "' and collaborator '" + nameB
+                            + "' both use tab \"" + a.tab() + "\"");
+                }
+            }
+        }
+        for (String leadName : leadNames) {
+            Leader lead = fleet.leaders().get(leadName);
+            if (lead == null || lead.tab() == null || lead.tab().isBlank()) {
+                continue;
+            }
+            for (String collabName : collabNames) {
+                Collaborator collaborator = fleet.collaborators().get(collabName);
+                if (collaborator == null || collaborator.tab() == null
+                        || collaborator.tab().isBlank()) {
+                    continue;
+                }
+                if (lead.tab().equalsIgnoreCase(collaborator.tab())) {
+                    collisions.add("lead '" + leadName + "' and collaborator '" + collabName
+                            + "' both use tab \"" + lead.tab() + "\"");
+                }
+            }
+        }
         if (collisions.isEmpty()) {
             return;
         }
         throw new IllegalStateException("refusing to start: " + String.join("; ", collisions)
-                + ". Tab identity is matched exactly, so only one of two leads sharing a tab can "
-                + "ever be found — the other is silently unreachable. Give each lead its own "
-                + "exact tab.");
+                + ". Tab identity is matched exactly, so only one of two entries sharing a tab can "
+                + "ever be found — the other is silently unreachable. Give each lead and "
+                + "collaborator its own exact tab.");
     }
 
     private static boolean templateCanRenderAs(String template, String tab) {
@@ -2785,25 +2874,29 @@ public record FleetConfig(
 
     /**
      * Reject a profile that places its members by {@code "pane"} while any {@code fleet.leaders}
-     * entry names a {@code tab}. A pane-placed member lands inside the focused tab rather than its
-     * own, so it can land inside a lead's own labelled tab. {@link
-     * dev.ltms.fleet.herdr.LeadTabScanner} identifies a lead purely by that tab's label — it does
-     * not exclude the member space — so a member that ends up there would be read back as the lead
-     * and granted spawn/stop/send on the whole fleet.
+     * or {@code fleet.collaborators} entry names a {@code tab}. A pane-placed member lands inside
+     * the focused tab rather than its own, so it can land inside a lead's or collaborator's own
+     * labelled tab. {@link dev.ltms.fleet.herdr.LeadTabScanner} identifies a lead or collaborator
+     * purely by that tab's label — it does not exclude the member space — so a member that ends up
+     * there, while its pane carries no entry in the spawned-member roster, is read back as that
+     * lead or collaborator and granted that identity's authority.
      *
-     * <p>Only a leader with a non-blank {@code tab} is in scope: one with no {@code tab} feeds
+     * <p>Only an entry with a non-blank {@code tab} is in scope: one with no {@code tab} feeds
      * nothing into {@link dev.ltms.fleet.herdr.LeadTabScanner}, so it creates no hazard here.
      *
      * @throws IllegalStateException when any {@code profiles:} entry is pane-placed while any
-     *                               {@code fleet.leaders} entry names a non-blank {@code tab}
+     *                               {@code fleet.leaders} or {@code fleet.collaborators} entry
+     *                               names a non-blank {@code tab}
      */
     public void validatePanePlacementAgainstLeadTabs() {
-        if (fleet == null || fleet.leaders().isEmpty()) {
+        if (fleet == null) {
             return;
         }
         boolean anyLeaderHasTab = fleet.leaders().values().stream()
                 .anyMatch(leader -> leader != null && leader.tab() != null && !leader.tab().isBlank());
-        if (!anyLeaderHasTab) {
+        boolean anyCollaboratorHasTab = fleet.collaborators().values().stream()
+                .anyMatch(c -> c != null && c.tab() != null && !c.tab().isBlank());
+        if (!anyLeaderHasTab && !anyCollaboratorHasTab) {
             return;
         }
         List<String> bad = new ArrayList<>();
@@ -2816,10 +2909,12 @@ public record FleetConfig(
             return;
         }
         throw new IllegalStateException("refusing to start: profile(s) " + bad
-                + " use placement: pane while fleet.leaders names a tab. A pane-placed member can "
-                + "land inside a lead's labelled tab and be read back as the lead, granted "
-                + "spawn/stop/send on the whole fleet. Set placement: tab for each named profile, "
-                + "or remove the tab from every fleet.leaders entry.");
+                + " use placement: pane while fleet.leaders or fleet.collaborators names a tab. A "
+                + "pane-placed member can land inside that labelled tab, and while its pane "
+                + "carries no entry in the spawned-member roster, it is read back as the lead or "
+                + "collaborator and granted that identity's authority. Set placement: tab for "
+                + "each named profile, or remove the tab from every fleet.leaders and "
+                + "fleet.collaborators entry.");
     }
 
     /**
@@ -2926,8 +3021,14 @@ public record FleetConfig(
      * so duplicates are unrepresentable by construction once loaded — and {@link #load(Path)}
      * already rejects a duplicated slot name at parse time, before the map collapses.
      *
-     * @throws IllegalStateException when a slot names no profile or an unknown one, or when a lead
-     *                               can be neither found nor created, naming the offending entry
+     * <p>Also rejects a {@code fleet.collaborators} entry with no (or a blank) {@code tab}. A
+     * {@code profile}-less lead is still useful recognise-only — {@code tab} is the only field
+     * that matters to it either way. A collaborator carries no other field at all, so a blank
+     * {@code tab} leaves nothing for the entry to mean.
+     *
+     * @throws IllegalStateException when a slot names no profile or an unknown one, when a lead
+     *                               can be neither found nor created, or when a collaborator names
+     *                               no tab, naming the offending entry
      */
     public void validateMembers() {
         if (fleet == null) {
@@ -2965,6 +3066,16 @@ public record FleetConfig(
                         + "auto-launched, labelled) purely by its tab, so every entry must name one.");
             }
         });
+        fleet.collaborators().forEach((name, collaborator) -> {
+            if (collaborator == null) {
+                return;
+            }
+            if (collaborator.tab() == null || collaborator.tab().isBlank()) {
+                bad.add("fleet.collaborators." + name + " has no tab: — a collaborator is "
+                        + "recognised purely by its tab, and carries no other field, so every "
+                        + "entry must name one.");
+            }
+        });
         if (!bad.isEmpty()) {
             throw new IllegalStateException("refusing to start: " + String.join(" ", bad));
         }

fleetd/src/main/java/dev/ltms/fleet/herdr/HerdrRouter.java

@@ -11,12 +11,18 @@ public final class HerdrRouter implements AutoCloseable {
     private final AgentControl memberAgents;
     private final WorkspaceControl leadSpaces;
     private final WorkspaceControl memberSpaces;
-    private final Predicate<String> isLead;
+    private final Predicate<String> routeToLead;
 
-    public HerdrRouter(HerdrClient lead, HerdrClient member, Predicate<String> isLead) {
+    /**
+     * @param routeToLead true for a terminal whose pane lives in the lead herdr daemon — a lead's
+     *                     own pane or a configured collaborator's, both opened by a person at a
+     *                     terminal rather than spawned, so both are found in the lead daemon rather
+     *                     than the member one
+     */
+    public HerdrRouter(HerdrClient lead, HerdrClient member, Predicate<String> routeToLead) {
         this.lead = Objects.requireNonNull(lead, "lead");
         this.member = member != null ? member : lead;
-        this.isLead = Objects.requireNonNull(isLead, "isLead");
+        this.routeToLead = Objects.requireNonNull(routeToLead, "routeToLead");
         leadAgents = new AgentControl(this.lead);
         memberAgents = this.member == this.lead ? leadAgents : new AgentControl(this.member);
         leadSpaces = new WorkspaceControl(this.lead);
@@ -27,7 +33,7 @@ public final class HerdrRouter implements AutoCloseable {
     public WorkspaceControl leadSpaces() { return leadSpaces; }
     public AgentControl memberAgents() { return memberAgents; }
     public WorkspaceControl memberSpaces() { return memberSpaces; }
-    public AgentControl agentsFor(String targetId) { return isLead.test(targetId) ? leadAgents : memberAgents; }
+    public AgentControl agentsFor(String targetId) { return routeToLead.test(targetId) ? leadAgents : memberAgents; }
 
     HerdrClient leadClient() { return lead; }
     HerdrClient memberClient() { return member; }

fleetd/src/main/java/dev/ltms/fleet/herdr/LeadTabScanner.java

@@ -96,13 +96,19 @@ public final class LeadTabScanner implements Supplier<Map<String, String>> {
 
     private static final Logger log = LoggerFactory.getLogger(LeadTabScanner.class);
 
+    /** What a matched tab names: a lead or a collaborator. */
+    private enum Kind { LEAD, COLLABORATOR }
+
+    /** One matched tab's name and what it names. */
+    private record Entry(String name, Kind kind) {}
+
     private final HerdrClient herdr;
-    private final Map<String, String> tabToName;
+    private final Map<String, Entry> tabToEntry;
     private final Set<String> excludedWorkspaceLabels;
     private final long ttlNanos;
     private final LongSupplier clock;
 
-    private Map<String, String> cached = Map.of();
+    private Map<String, Entry> cached = Map.of();
     private long scannedAtNanos;
     private boolean everScanned;
 
@@ -126,26 +132,53 @@ public final class LeadTabScanner implements Supplier<Map<String, String>> {
      */
     public LeadTabScanner(HerdrClient herdr, Map<String, String> tabToName,
                           Set<String> excludedWorkspaceLabels, long ttlNanos, LongSupplier clock) {
+        this(herdr, tabToName, Map.of(), excludedWorkspaceLabels, ttlNanos, clock);
+    }
+
+    /**
+     * As {@link #LeadTabScanner(HerdrClient, Map, Set, long, LongSupplier)}, additionally scanning
+     * for configured collaborator tabs in the same pass.
+     *
+     * @param collaboratorTabToName every configured collaborator's exact tab label → its name
+     *                              ({@code fleet.collaborators.<name>.tab}), matched the same way as
+     *                              {@code tabToName}
+     */
+    public LeadTabScanner(HerdrClient herdr, Map<String, String> tabToName,
+                          Map<String, String> collaboratorTabToName,
+                          Set<String> excludedWorkspaceLabels, long ttlNanos, LongSupplier clock) {
         this.herdr = herdr;
-        this.tabToName = normalize(tabToName);
+        this.tabToEntry = buildTabIndex(tabToName, collaboratorTabToName);
         this.excludedWorkspaceLabels = excludedWorkspaceLabels == null
                 ? Set.of() : Set.copyOf(excludedWorkspaceLabels);
         this.ttlNanos = ttlNanos;
         this.clock = clock;
     }
 
-    /** Keys stripped and lower-cased once, so every lookup is a plain map hit. */
-    private static Map<String, String> normalize(Map<String, String> tabToName) {
-        if (tabToName == null || tabToName.isEmpty()) {
-            return Map.of();
+    /**
+     * Keys stripped and lower-cased once, so every lookup is a plain map hit. Leads and
+     * collaborators merge into a single index, so {@link #scan()} matches both kinds in one pass
+     * over the tab list; a label naming both a lead and a collaborator takes the lead entry —
+     * leads are put last, so a colliding key's lead entry is the one that overwrites — since a lead
+     * can already do everything a collaborator can. Config validation already refuses a lead and a
+     * collaborator sharing one exact tab, so this ordering is defence in depth, not the control.
+     */
+    private static Map<String, Entry> buildTabIndex(Map<String, String> tabToName,
+                                                     Map<String, String> collaboratorTabToName) {
+        Map<String, Entry> out = new LinkedHashMap<>();
+        putNormalized(out, collaboratorTabToName, Kind.COLLABORATOR);
+        putNormalized(out, tabToName, Kind.LEAD);
+        return Collections.unmodifiableMap(out);
+    }
+
+    private static void putNormalized(Map<String, Entry> out, Map<String, String> tabToName, Kind kind) {
+        if (tabToName == null) {
+            return;
         }
-        Map<String, String> out = new LinkedHashMap<>();
         tabToName.forEach((tab, name) -> {
             if (tab != null && !tab.isBlank() && name != null && !name.isBlank()) {
-                out.put(tab.strip().toLowerCase(Locale.ROOT), name);
+                out.put(tab.strip().toLowerCase(Locale.ROOT), new Entry(name, kind));
             }
         });
-        return Collections.unmodifiableMap(out);
     }
 
     /**
@@ -156,6 +189,29 @@ public final class LeadTabScanner implements Supplier<Map<String, String>> {
      */
     @Override
     public synchronized Map<String, String> get() {
+        return byKind(refresh(), Kind.LEAD);
+    }
+
+    /**
+     * The current {@code terminal_id → collaborator name} map, sharing the same scan and cache as
+     * {@link #get()} — both kinds are matched in one pass, so this never costs a second herdr call.
+     */
+    public synchronized Map<String, String> collaborators() {
+        return byKind(refresh(), Kind.COLLABORATOR);
+    }
+
+    private static Map<String, String> byKind(Map<String, Entry> entries, Kind kind) {
+        Map<String, String> out = new LinkedHashMap<>();
+        entries.forEach((terminal, entry) -> {
+            if (entry.kind() == kind) {
+                out.put(terminal, entry.name());
+            }
+        });
+        return Collections.unmodifiableMap(out);
+    }
+
+    /** Rescans if the cache has expired, otherwise returns the cached answer. */
+    private Map<String, Entry> refresh() {
         long now = clock.getAsLong();
         if (everScanned && now - scannedAtNanos < ttlNanos) {
             return cached;
@@ -165,21 +221,21 @@ public final class LeadTabScanner implements Supplier<Map<String, String>> {
         scannedAtNanos = now;
         everScanned = true;
         try {
-            Map<String, String> fresh = scan();
+            Map<String, Entry> fresh = scan();
             if (!fresh.equals(cached)) {
-                log.info("lead panes: {}", fresh);
+                log.info("lead/collaborator panes: {}", fresh);
             }
             cached = fresh;
         } catch (HerdrException e) {
-            log.warn("lead-tab scan failed, keeping the {} lead(s) already known: {}",
+            log.warn("lead-tab scan failed, keeping the {} entr(y/ies) already known: {}",
                     cached.size(), e.getMessage());
         }
         return cached;
     }
 
     /** One full pass: labelled tabs → live agents in them → those panes' terminals. */
-    private Map<String, String> scan() {
-        Map<String, String> nameByTab = new LinkedHashMap<>();
+    private Map<String, Entry> scan() {
+        Map<String, Entry> entryByTab = new LinkedHashMap<>();
         for (JsonNode w : herdr.call("workspace.list").path("workspaces")) {
             Workspace ws = Workspace.from(w);
             if (ws.workspaceId() == null || excludedWorkspaceLabels.contains(ws.label())) {
@@ -187,21 +243,22 @@ public final class LeadTabScanner implements Supplier<Map<String, String>> {
             }
             for (JsonNode t : herdr.call("tab.list", Map.of("workspace_id", ws.workspaceId())).path("tabs")) {
                 Tab tab = Tab.from(t);
-                String name = leadNameOf(tab.label());
-                if (name != null && tab.tabId() != null) {
-                    nameByTab.put(tab.tabId(), name);
+                Entry entry = entryOf(tab.label());
+                if (entry != null && tab.tabId() != null) {
+                    entryByTab.put(tab.tabId(), entry);
                 }
             }
         }
 
-        if (nameByTab.isEmpty()) {
+        if (entryByTab.isEmpty()) {
             gracedTerminals = Set.of();
             return Map.of();
         }
 
-        // fleetd #359: a labelled tab is only a lead when herdr also reports a running agent in
-        // it — the same liveness signal LeadLauncher.countLeads trusts for the identical purpose.
-        // Without this, a tab left behind by a session that has since died reads as live forever.
+        // fleetd #359: a labelled tab is only a lead (or collaborator) when herdr also reports a
+        // running agent in it — the same liveness signal LeadLauncher.countLeads trusts for the
+        // identical purpose. Without this, a tab left behind by a session that has since died reads
+        // as live forever.
         Set<String> tabsWithAgent = new HashSet<>();
         for (JsonNode a : herdr.call("agent.list").path("agents")) {
             String tabId = a.path("tab_id").asText(null);
@@ -210,18 +267,18 @@ public final class LeadTabScanner implements Supplier<Map<String, String>> {
             }
         }
 
-        Map<String, String> byTerminal = new LinkedHashMap<>();
+        Map<String, Entry> byTerminal = new LinkedHashMap<>();
         Set<String> stillGraced = new HashSet<>();
         // One pane.list for every tab: panes carry tab_id, so the join is local.
         for (JsonNode p : herdr.call("pane.list", Map.of()).path("panes")) {
             String tabId = p.path("tab_id").asText(null);
-            String name = nameByTab.get(tabId);
+            Entry entry = entryByTab.get(tabId);
             String terminal = p.path("terminal_id").asText(null);
-            if (name == null || terminal == null || terminal.isBlank()) {
+            if (entry == null || terminal == null || terminal.isBlank()) {
                 continue;
             }
             if (tabsWithAgent.contains(tabId)) {
-                byTerminal.put(terminal, name);
+                byTerminal.put(terminal, entry);
                 continue;
             }
             // No agent reported for this tab, but its tab/pane are still here — this is the
@@ -230,7 +287,7 @@ public final class LeadTabScanner implements Supplier<Map<String, String>> {
             // reported as live; a terminal we never reported live gets none, so the original #359
             // fix (a genuinely dead tab is never reported) is unaffected for the common case.
             if (cached.containsKey(terminal) && !gracedTerminals.contains(terminal)) {
-                byTerminal.put(terminal, name);
+                byTerminal.put(terminal, entry);
                 stillGraced.add(terminal);
             }
         }
@@ -239,18 +296,19 @@ public final class LeadTabScanner implements Supplier<Map<String, String>> {
     }
 
     /**
-     * The lead name a tab label declares, or {@code null} if it names none of the configured leads.
+     * The entry a tab label declares, or {@code null} if it names neither a configured lead nor a
+     * configured collaborator.
      *
-     * <p>Exact match (case-insensitive, ends stripped) against {@link #tabToName} — no prefix
+     * <p>Exact match (case-insensitive, ends stripped) against {@link #tabToEntry} — no prefix
      * stripping, so an operator's {@code "lead: something-else"} tab is never mistaken for a
      * configured lead just because it shares a prefix. The match strips a trailing
      * {@link PendingCloseMarker} first, so a tab {@code LeadLauncher} has flagged as maybe-dead but
      * not yet closed keeps resolving normally while that reconcile is pending.
      */
-    private String leadNameOf(String label) {
+    private Entry entryOf(String label) {
         if (label == null) {
             return null;
         }
-        return tabToName.get(PendingCloseMarker.strip(label).toLowerCase(Locale.ROOT));
+        return tabToEntry.get(PendingCloseMarker.strip(label).toLowerCase(Locale.ROOT));
     }
 }

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

@@ -114,6 +114,13 @@ public final class FleetMcp {
      * dev.ltms.fleet.herdr.PaneLocator} — that a real assembly wired up. See {@link #identity()}.
      */
     private final ConnectionIdentity identity;
+    /**
+     * Kept as a field (rather than only captured by the {@code contextExtractor} closure) so
+     * {@link #denyFor} can read {@link CallerResolver#knownLeadOrCollaborator()} — the classifier a
+     * collaborator's {@code SEND} is checked against, built from the same lead and collaborator
+     * maps {@link #identity}-based resolution reads.
+     */
+    private final CallerResolver callers;
     private final Metrics metrics;      // CB-502: null → auth failures not counted
     private final CapacitySource capacity;
     private final HealthCoverageSource healthCoverage;
@@ -409,6 +416,7 @@ public final class FleetMcp {
         this.authorizationEnforced = Objects.requireNonNull(authorizationMode, "authorizationMode")
                 == AuthorizationMode.ENFORCED;
         this.identity = identity;
+        this.callers = callers;
         this.leadChannel = leadChannel;
         this.peers = peers == null ? List.of() : List.copyOf(peers);
         this.capacity = capacity;
@@ -552,6 +560,7 @@ public final class FleetMcp {
                     return listFleet(workers, sessions, messages, capacity, healthCoverage, loopHealth, quarantine, outage,
                             leadSeats, leadContextGauge, leadConfigDirs, callers.leads(),
                             callerTerminal(exchange),
+                            callers.collaborators(), collaboratorsVisibleTo(principal(exchange)),
                             new CoordinationSource(leadChannel, peers),
                             coordinatorVisibleTo(principal(exchange)));
                 };
@@ -689,7 +698,7 @@ 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, callers.knownLeadOrCollaborator())) {
             if (action != Authz.Action.READ && action != Authz.Action.TASK_READ) {
                 AuditLog.allowed(caller, action, target); // reads would drown the trail
             }
@@ -735,6 +744,21 @@ public final class FleetMcp {
         return caller.isPrimary();
     }
 
+    /**
+     * fleetd #703: who may see {@code fleet_list}'s {@code collaborators} array — a roster of the
+     * human-opened tabs this daemon recognises as named peers. Visible to exactly the roles that
+     * may {@link Authz.Action#SEND} to a named peer ({@code Authz.java}'s {@code SEND} case):
+     * the primary, an architect, and a collaborator (reaching another collaborator or a lead). A
+     * worker holds {@code READ} but can never {@code SEND} to a collaborator, so listing them to a
+     * worker would expose which human tabs exist on the host with no use to that caller. Split out
+     * for the same reason as {@link #coordinatorVisibleTo}: the decision must be unit-testable
+     * without fabricating an SDK {@code McpSyncServerExchange}, and the handler must call this
+     * named predicate rather than inlining the check.
+     */
+    static boolean collaboratorsVisibleTo(Principal caller) {
+        return caller.isPrimary() || caller.isArchitect() || caller.isCollaborator();
+    }
+
     /** The worker identity resolved from this call's connection, or {@code null} if the primary. */
     private static String callerTerminal(McpSyncServerExchange exchange) {
         Object v = exchange.transportContext().get(CALLER_TERMINAL);
@@ -1309,6 +1333,18 @@ 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
@@ -1741,7 +1777,8 @@ public final class FleetMcp {
                                                Map<String, String> leads, String selfTerm,
                                                CoordinationSource coordination) {
         return listFleet(workers, sessions, messages, capacity, healthCoverage, loopHealth, quarantine,
-                OutageSource.none(), LeadSeatSource.none(), new LeadContextGauge(), LeadConfigDirSource.none(), leads, selfTerm, coordination, false);
+                OutageSource.none(), LeadSeatSource.none(), new LeadContextGauge(), LeadConfigDirSource.none(), leads, selfTerm,
+                Map.of(), false, coordination, false);
     }
 
     /** As above, plus fleetd #201 Unit 5 cool-off facts (see {@link OutageSource}). */
@@ -1750,7 +1787,8 @@ public final class FleetMcp {
                                                QuarantineSource quarantine, OutageSource outage,
                                                Map<String, String> leads, String selfTerm) {
         return listFleet(workers, sessions, messages, capacity, healthCoverage, LoopHealthSource.none(), quarantine, outage,
-                LeadSeatSource.none(), new LeadContextGauge(), LeadConfigDirSource.none(), leads, selfTerm, CoordinationSource.none(), false);
+                LeadSeatSource.none(), new LeadContextGauge(), LeadConfigDirSource.none(), leads, selfTerm,
+                Map.of(), false, CoordinationSource.none(), false);
     }
 
     /**
@@ -1767,7 +1805,8 @@ public final class FleetMcp {
                                                QuarantineSource quarantine, Map<String, String> leads, String selfTerm,
                                                CoordinationSource coordination) {
         return listFleet(workers, sessions, messages, capacity, healthCoverage, LoopHealthSource.none(), quarantine, OutageSource.none(),
-                LeadSeatSource.none(), new LeadContextGauge(), LeadConfigDirSource.none(), leads, selfTerm, coordination, false);
+                LeadSeatSource.none(), new LeadContextGauge(), LeadConfigDirSource.none(), leads, selfTerm,
+                Map.of(), false, coordination, false);
     }
 
     /** As above, plus fleetd #201 Unit 5 cool-off facts (see {@link OutageSource}). */
@@ -1776,7 +1815,8 @@ public final class FleetMcp {
                                                QuarantineSource quarantine, OutageSource outage,
                                                Map<String, String> leads, String selfTerm, CoordinationSource coordination) {
         return listFleet(workers, sessions, messages, capacity, healthCoverage, LoopHealthSource.none(), quarantine, outage,
-                LeadSeatSource.none(), new LeadContextGauge(), LeadConfigDirSource.none(), leads, selfTerm, coordination, false);
+                LeadSeatSource.none(), new LeadContextGauge(), LeadConfigDirSource.none(), leads, selfTerm,
+                Map.of(), false, coordination, false);
     }
 
     /**
@@ -1798,7 +1838,8 @@ public final class FleetMcp {
                                                LeadSeatSource leadSeats, Map<String, String> leads, String selfTerm,
                                                CoordinationSource coordination) {
         return listFleet(workers, sessions, messages, capacity, healthCoverage, LoopHealthSource.none(), quarantine, outage,
-                leadSeats, new LeadContextGauge(), LeadConfigDirSource.none(), leads, selfTerm, coordination, false);
+                leadSeats, new LeadContextGauge(), LeadConfigDirSource.none(), leads, selfTerm,
+                Map.of(), false, coordination, false);
     }
 
     /**
@@ -1822,7 +1863,8 @@ public final class FleetMcp {
                                                 LeadSeatSource leadSeats, Map<String, String> leads, String selfTerm,
                                                 CoordinationSource coordination, boolean callerIsPrimary) {
         return listFleet(workers, sessions, messages, capacity, healthCoverage, LoopHealthSource.none(), quarantine,
-                outage, leadSeats, new LeadContextGauge(), LeadConfigDirSource.none(), leads, selfTerm, coordination, callerIsPrimary);
+                outage, leadSeats, new LeadContextGauge(), LeadConfigDirSource.none(), leads, selfTerm,
+                Map.of(), false, coordination, callerIsPrimary);
     }
 
     /**
@@ -1832,6 +1874,13 @@ public final class FleetMcp {
      * matter); the one caller that matters for caching, {@code fleet_list}'s MCP handler, passes
      * its own single long-lived instance instead (see {@code FleetMcp}'s {@code leadContextGauge}
      * field).
+     *
+     * @param collaborators        terminal_id → collaborator name, live from the resolver
+     *                              ({@link dev.ltms.fleet.auth.CallerResolver#collaborators()})
+     * @param collaboratorsVisible whether this caller may see the {@code collaborators} array (see
+     *                             {@link #collaboratorsVisibleTo}); every wrapper overload above
+     *                             passes {@code false}, so a test that wants the row must call this
+     *                             overload with an explicit {@code true}
      */
     static McpSchema.CallToolResult listFleet(PeerLauncher workers, SessionManager sessions, MessageService messages,
                                                  CapacitySource capacity, HealthCoverageSource healthCoverage,
@@ -1840,6 +1889,7 @@ public final class FleetMcp {
                                                LeadSeatSource leadSeats, LeadContextGauge contextGauge,
                                                LeadConfigDirSource leadConfigDirs,
                                                Map<String, String> leads, String selfTerm,
+                                               Map<String, String> collaborators, boolean collaboratorsVisible,
                                                CoordinationSource coordination, boolean callerIsPrimary) {
         try {
             Map<String, Agent> live = workers.list().stream()
@@ -1866,6 +1916,16 @@ public final class FleetMcp {
             result.put("loopHealth", Map.of(
                     "statusPoller", loopHealth.statusPoller().get().name(),
                     "sessionReaper", loopHealth.sessionReaper().get().name()));
+            // fleetd #703: a collaborator tab is a person's own tab, so the row is assembled and
+            // included only for the roles that may SEND to a named peer -- gate BEFORE assembling
+            // it, same reason as the coordinator row just below: the key must be absent for a
+            // worker, never present-and-empty.
+            if (collaboratorsVisible) {
+                result.put("collaborators", collaborators.entrySet().stream()
+                        .sorted(Map.Entry.comparingByValue())
+                        .map(e -> collaboratorRow(e.getKey(), e.getValue()))
+                        .toList());
+            }
             // fleetd #439: coordinator/coordinatorView is lead-to-lead coordination state and must
             // never reach a worker or an architect -- gate BEFORE assembling it, not after, so the
             // key is absent rather than present-and-empty.
@@ -2177,6 +2237,20 @@ public final class FleetMcp {
         return m;
     }
 
+    /**
+     * fleetd #703: one row of the {@code collaborators} array — a named peer's registry name and
+     * the herdr {@code terminal_id} a {@code fleet_send} must target to reach it. No status, no
+     * context gauge, no profile: a collaborator is never spawned and carries no profile, so those
+     * fields have no meaning for it, and the scan behind {@code terminal} only reports a tab it
+     * actually found in herdr, so a tab nobody has open does not appear here at all.
+     */
+    private static Map<String, Object> collaboratorRow(String terminal, String name) {
+        Map<String, Object> m = new LinkedHashMap<>();
+        m.put("name", name);
+        m.put("sessionId", terminal);
+        return m;
+    }
+
     /**
      * Reads the lead context gauge for one lead. {@code configDir} is this lead's configured
      * {@code CLAUDE_CONFIG_DIR} override (see {@link LeadConfigDirSource}), derived from
@@ -2402,7 +2476,12 @@ public final class FleetMcp {
                         + "msgId/from/preview, never the full body), and one row per coordinator.peers "
                         + "coord-id ('peers': coordId/reachable, plus pending/consumers when reachable) — "
                         + "this is peer DISCOVERY for cross-host leads, distinct from the local 'leads' "
-                        + "array above. It is omitted entirely when no coordinator is configured.",
+                        + "array above. It is omitted entirely when no coordinator is configured. A "
+                        + "'collaborators' array, visible only to the primary, an architect, and a "
+                        + "collaborator (never a worker), reports every other named peer tab this daemon "
+                        + "recognises: each row is 'name' (its registry name) and 'sessionId' (the "
+                        + "terminal id a fleet_send targets to reach it). Absent entirely for a worker, "
+                        + "whatever is configured.",
                 objectSchema(Map.of(), List.of()));
     }
 

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

@@ -266,6 +266,21 @@ 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}.
+     *
+     * @param knownLeadOrCollaborator the classifier a collaborator's {@code SEND} is checked
+     *                                against; pass {@link #auth}'s own {@code
+     *                                knownLeadOrCollaborator()} to exercise the real production
+     *                                gate, as {@link #allow} does
+     */
+    static boolean permitsFor(Principal caller, Authz.Action action, String target,
+                              Predicate<String> knownLeadOrCollaborator) {
+        return Authz.permits(caller, action, target, knownLeadOrCollaborator);
+    }
+
     /**
      * 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 +294,7 @@ 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, auth.knownLeadOrCollaborator())) {
             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/FleetDeliverabilityTest.java

@@ -14,10 +14,12 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * CB-534: the injector's readiness gate must open for a lead as well as for a present worker.
+ * fleetd #669 follow-up: the same gate must also open for a collaborator, which — like a lead —
+ * is never enrolled in {@link MemberPresence} and never discovered by the lead scan.
  *
- * <p>The bug these cover was silent and slow: a lead was never marked present (only workers are), so
- * every lead→lead delivery sat on the gate for the full readiness grace and failed ~60s later without
- * a keystroke ever reaching the pane.
+ * <p>The bug these cover was silent and slow: a lead (and later a collaborator) was never marked
+ * present (only workers are) and never counted as a lead, so every send to one sat on the gate for
+ * the full readiness grace and failed ~60s later without a keystroke ever reaching the pane.
  */
 class FleetDeliverabilityTest {
 
@@ -25,19 +27,25 @@ class FleetDeliverabilityTest {
         return () -> m;
     }
 
+    private static Supplier<Map<String, String>> collaborators(Map<String, String> m) {
+        return () -> m;
+    }
+
     @Test
     @DisplayName("a worker that has connected its MCP is deliverable")
     void presentWorkerIsDeliverable() {
         MemberPresence presence = new MemberPresence();
         presence.markPresent("term_worker");
 
-        assertTrue(Fleetd.deliverableTo(presence, leads(Map.of())).test("term_worker"));
+        assertTrue(Fleetd.deliverableTo(presence, leads(Map.of()), collaborators(Map.of()))
+                .test("term_worker"));
     }
 
     @Test
     @DisplayName("a worker still in its boot window is held back")
     void absentWorkerIsNotDeliverable() {
-        assertFalse(Fleetd.deliverableTo(new MemberPresence(), leads(Map.of())).test("term_booting"));
+        assertFalse(Fleetd.deliverableTo(new MemberPresence(), leads(Map.of()), collaborators(Map.of()))
+                .test("term_booting"));
     }
 
     @Test
@@ -45,19 +53,31 @@ class FleetDeliverabilityTest {
     void leadIsDeliverableWithoutPresence() {
         MemberPresence presence = new MemberPresence();
         Predicate<String> deliverable =
-                Fleetd.deliverableTo(presence, leads(Map.of("term_lead", "opus-5.0")));
+                Fleetd.deliverableTo(presence, leads(Map.of("term_lead", "opus-5.0")), collaborators(Map.of()));
 
         assertFalse(presence.isPresent("term_lead"), "a lead is never enrolled in worker presence");
         assertTrue(deliverable.test("term_lead"), "…and must be deliverable anyway");
     }
 
     @Test
-    @DisplayName("an unknown terminal is deliverable to neither")
+    @DisplayName("a collaborator is deliverable without ever being marked present or scanned as a lead")
+    void collaboratorIsDeliverableWithoutPresenceOrLeadStatus() {
+        MemberPresence presence = new MemberPresence();
+        Predicate<String> deliverable = Fleetd.deliverableTo(presence, leads(Map.of()),
+                collaborators(Map.of("term_collab", "kevin")));
+
+        assertFalse(presence.isPresent("term_collab"), "a collaborator is never enrolled in worker presence");
+        assertTrue(deliverable.test("term_collab"), "…and must be deliverable anyway");
+    }
+
+    @Test
+    @DisplayName("an unknown terminal is deliverable to none of presence, leads, or collaborators")
     void strangerIsNotDeliverable() {
         MemberPresence presence = new MemberPresence();
         presence.markPresent("term_worker");
 
-        assertFalse(Fleetd.deliverableTo(presence, leads(Map.of("term_lead", "opus-5.0")))
+        assertFalse(Fleetd.deliverableTo(presence, leads(Map.of("term_lead", "opus-5.0")),
+                        collaborators(Map.of("term_collab", "kevin")))
                 .test("term_stranger"));
     }
 
@@ -65,22 +85,47 @@ class FleetDeliverabilityTest {
     @DisplayName("a lead discovered after startup becomes deliverable with no restart")
     void leadSetIsReadThroughOnEveryCall() {
         Map<String, String> discovered = new HashMap<>();
-        Predicate<String> deliverable = Fleetd.deliverableTo(new MemberPresence(), leads(discovered));
+        Predicate<String> deliverable =
+                Fleetd.deliverableTo(new MemberPresence(), leads(discovered), collaborators(Map.of()));
 
         assertFalse(deliverable.test("term_late"));
         discovered.put("term_late", "gpt-sol-5.6"); // leadScan picks up a newly labelled tab
         assertTrue(deliverable.test("term_late"), "the supplier must be re-read, not snapshotted");
     }
 
+    @Test
+    @DisplayName("a collaborator discovered after startup becomes deliverable with no restart")
+    void collaboratorSetIsReadThroughOnEveryCall() {
+        Map<String, String> discovered = new HashMap<>();
+        Predicate<String> deliverable =
+                Fleetd.deliverableTo(new MemberPresence(), leads(Map.of()), collaborators(discovered));
+
+        assertFalse(deliverable.test("term_late_collab"));
+        discovered.put("term_late_collab", "kevin"); // the same tab scan picks up a newly labelled collaborator tab
+        assertTrue(deliverable.test("term_late_collab"), "the supplier must be re-read, not snapshotted");
+    }
+
     @Test
     @DisplayName("forgetting a torn-down worker does not strip a lead of its deliverability")
     void forgetDoesNotDisarmALead() {
         MemberPresence presence = new MemberPresence();
         Predicate<String> deliverable =
-                Fleetd.deliverableTo(presence, leads(Map.of("term_lead", "opus-5.0")));
+                Fleetd.deliverableTo(presence, leads(Map.of("term_lead", "opus-5.0")), collaborators(Map.of()));
 
         presence.forget("term_lead"); // the injector's cleanup path runs against every target
 
         assertTrue(deliverable.test("term_lead"));
     }
+
+    @Test
+    @DisplayName("forgetting a torn-down worker does not strip a collaborator of its deliverability")
+    void forgetDoesNotDisarmACollaborator() {
+        MemberPresence presence = new MemberPresence();
+        Predicate<String> deliverable = Fleetd.deliverableTo(presence, leads(Map.of()),
+                collaborators(Map.of("term_collab", "kevin")));
+
+        presence.forget("term_collab"); // the injector's cleanup path runs against every target
+
+        assertTrue(deliverable.test("term_collab"));
+    }
 }

fleetd/src/test/java/dev/ltms/fleet/FleetdAssemblyCollaboratorHerdrRoutingTest.java

@@ -0,0 +1,165 @@
+package dev.ltms.fleet;
+
+import dev.ltms.fleet.config.ConfigRef;
+import dev.ltms.fleet.config.FleetConfig;
+import dev.ltms.fleet.guard.SubscriptionGuard;
+import dev.ltms.fleet.herdr.FakeHerdr;
+import dev.ltms.fleet.herdr.HerdrClient;
+import dev.ltms.fleet.msg.ReplyInbox;
+import io.javalin.Javalin;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.function.LongSupplier;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertSame;
+
+/**
+ * fleetd #669 Unit E. Reaches the real {@link dev.ltms.fleet.herdr.HerdrRouter} that {@link
+ * FleetdAssembly#assembleAndStart} builds and wires — not a copy built for this test — and proves
+ * that a configured collaborator's terminal routes to the LEAD herdr daemon.
+ *
+ * <p>Two distinct {@link FakeHerdr} instances are required, the same pattern {@code
+ * FleetdAssemblyConnectionIdentityTest} and {@code FleetdLeadRolloverAssemblyTest} already use:
+ * with one client shared between {@code herdrSocket} and {@code memberHerdrSocket},
+ * {@code HerdrRouter} folds {@code leadAgents} and {@code memberAgents} into the same instance
+ * (see its constructor), and {@code agentsFor} would return that one object regardless of whether
+ * the collaborator map was ever consulted — invisible to a mutation of the predicate this ticket
+ * fixes. This test's two sockets resolve to two different fakes, so the assertion only passes when
+ * the collaborator's terminal is actually recognised and routed to the lead one.
+ */
+class FleetdAssemblyCollaboratorHerdrRoutingTest {
+
+    private static final Path LEAD_SOCKET = Path.of("/fake/lead-herdr.sock");
+    private static final Path MEMBER_SOCKET = Path.of("/fake/member-herdr.sock");
+
+    private static final class RecordingResourcePorts implements ResourcePorts {
+        final Map<Path, HerdrClient> herdrsBySocket = new LinkedHashMap<>();
+        Runnable shutdownHook;
+
+        @Override
+        public Map<String, String> environment() {
+            return Map.of();
+        }
+
+        @Override
+        public HerdrClient connectHerdr(Path socketPath) {
+            HerdrClient client = herdrsBySocket.get(socketPath);
+            if (client == null) {
+                throw new IllegalStateException("no fake herdr registered for socket " + socketPath);
+            }
+            return client;
+        }
+
+        @Override
+        public Fleetd.AmqpOpener replyInboxOpener() {
+            return (uri, prefetch) -> new ReplyInbox() {
+                @Override public void own(String target) { }
+                @Override public void release(String target) { }
+                @Override public void publish(String target, String msgId, String content) { }
+                @Override public List<InboxMessage> peek(String target) { return List.of(); }
+                @Override public boolean ack(String target, String msgId) { return false; }
+            };
+        }
+
+        @Override
+        public Fleetd.LeadMailboxOpener leadMailboxOpener() {
+            return (uri, selfCoordId, prefetch) -> {
+                throw new UnsupportedOperationException(
+                        "leadMailboxOpener must not be called — no coordinator: block is configured");
+            };
+        }
+
+        @Override
+        public LongSupplier nanoClock() {
+            return System::nanoTime;
+        }
+
+        @Override
+        public LongSupplier wallClockNanos() {
+            return System::nanoTime;
+        }
+
+        @Override
+        public ScheduledExecutorService newScheduler(String purpose) {
+            return Executors.newSingleThreadScheduledExecutor();
+        }
+
+        @Override
+        public void addShutdownHook(Runnable hook) {
+            shutdownHook = hook;
+        }
+
+        @Override
+        public void startHttp(Javalin app, String host, int port) {
+            // Do not bind a real port in this assembly test.
+        }
+
+        @Override
+        public Runnable herdrPollWait() {
+            return () -> {
+                throw new UnsupportedOperationException("FakeHerdr is healthy; no poll wait is expected");
+            };
+        }
+    }
+
+    private static FleetConfig writeConfig(Path dir) throws Exception {
+        Path file = dir.resolve("fleetd.yaml");
+        Files.writeString(file, """
+                bind:
+                  host: 127.0.0.1
+                  port: 8765
+                herdrSocket: "%s"
+                memberHerdrSocket: "%s"
+                idleSleepGuard:
+                  enabled: false
+                fleet:
+                  collaborators:
+                    reviewer-alex:
+                      tab: "collab: alex"
+                profiles:
+                  sonnet:
+                    subscription: true
+                    argv: ["ccs", "sonnet"]
+                """.formatted(LEAD_SOCKET, MEMBER_SOCKET));
+        return FleetConfig.load(file);
+    }
+
+    @Test
+    void assembledRouterRoutesACollaboratorTerminalToTheLeadDaemon(@TempDir Path dir) throws Exception {
+        FleetConfig cfg = writeConfig(dir);
+        RecordingResourcePorts ports = new RecordingResourcePorts();
+
+        // The fixed FakeHerdr fixture already ties terminal "term_a" to a live agent on tab
+        // "w2:t7" (pane "w2:p7") — seeding only the tab LABEL to match the configured collaborator
+        // is enough to make LeadTabScanner resolve "term_a" as that collaborator. Seeded on the
+        // LEAD fake only: a collaborator's pane lives in the lead daemon, exactly like a lead's.
+        FakeHerdr lead = new FakeHerdr().withTab("w2", "w2:t7", "collab: alex");
+        FakeHerdr member = new FakeHerdr();
+        ports.herdrsBySocket.put(LEAD_SOCKET, lead);
+        ports.herdrsBySocket.put(MEMBER_SOCKET, member);
+
+        FleetdRuntime runtime = FleetdAssembly.assembleAndStart(new AssemblyInputs(cfg,
+                new ConfigRef(dir.resolve("fleetd.yaml"), cfg), new SubscriptionGuard(cfg.guard().hostSet())), ports);
+        try {
+            assertSame(runtime.router().leadAgents(), runtime.router().agentsFor("term_a"),
+                    "a configured collaborator's terminal must route to the LEAD daemon — "
+                            + "FleetdAssembly must wire the collaborator map into the router's "
+                            + "predicate, not just LeadTabScanner.get()");
+            assertSame(runtime.router().memberAgents(), runtime.router().agentsFor("term_shell"),
+                    "control: a terminal naming neither a lead nor a collaborator (term_shell, on "
+                            + "the unlabelled tab w2:t8) must still route to the member daemon");
+        } finally {
+            assertNotNull(ports.shutdownHook, "control: assembly must capture its shutdown hook");
+            ports.shutdownHook.run();
+        }
+    }
+}

fleetd/src/test/java/dev/ltms/fleet/FleetdAssemblyLeadTabScannerExclusionTest.java

@@ -31,8 +31,7 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * fleetd #670 — pins the {@code excludedWorkspaceLabels} argument {@link FleetdAssembly}'s
- * production boot path passes to {@link LeadTabScanner} at {@code FleetdAssembly.java:265}
- * ({@code Set.of()}).
+ * production boot path passes to {@link LeadTabScanner} ({@code Set.of()}).
  *
  * <p>{@code LeadTabScannerTest} already covers this constructor parameter, but it builds its own
  * {@link LeadTabScanner} with its own set, so it tests the seam and proves nothing about the
@@ -191,7 +190,7 @@ class FleetdAssemblyLeadTabScannerExclusionTest {
             Set<?> excluded = (Set<?>) excludedField.get(leads);
 
             assertTrue(excluded.isEmpty(),
-                    "FleetdAssembly.java:265 must pass an empty excludedWorkspaceLabels to "
+                    "FleetdAssembly must pass an empty excludedWorkspaceLabels to "
                             + "LeadTabScanner — scanning member tabs would demote the lead to a worker");
         } finally {
             assertNotNull(ports.shutdownHook, "control: assembly must capture its shutdown hook");

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/auth/CallerResolverTest.java

@@ -523,4 +523,129 @@ class CallerResolverTest {
         }
     }
 
+    // ── fleetd #669 Unit D: a live spawned member outranks every tab map ────────────────────────
+
+    /**
+     * Criterion 1: a terminal present in BOTH the spawned-member roster AND the lead tab map
+     * resolves as its member role, not as a lead — the roster is checked first, consulting no tab
+     * map at all when it matches.
+     */
+    @Test
+    void aSpawnedMemberWinsOverALeadTabForTheSamePane() {
+        Principal p = CallerResolver.withLeadsAndMembers(workerIdentity(), false, null,
+                        () -> Map.of("term_a", "opus-5.0"), new MemberRegistry(null),
+                        t -> "term_a".equals(t) ? MemberRole.DEV : null, Map::of)
+                .resolve("127.0.0.1", 42, null);
+
+        assertEquals(Role.WORKER, p.role(),
+                "a live spawned member's own identity must win over a tab map naming the same pane a lead");
+        assertEquals("term_a", p.terminal());
+    }
+
+    /** A spawned architect in the roster resolves ARCHITECT, carrying its bound slot's name. */
+    @Test
+    void aSpawnedArchitectInTheRosterResolvesArchitectWithItsSlotName() {
+        Principal p = CallerResolver.withLeadsAndMembers(workerIdentity(), false, null, Map::of,
+                        boundMembers("architect:lead-designer", MemberRole.ARCHITECT),
+                        t -> "term_a".equals(t) ? MemberRole.ARCHITECT : null, Map::of)
+                .resolve("127.0.0.1", 42, null);
+
+        assertEquals(Role.ARCHITECT, p.role());
+        assertEquals("lead-designer", p.name());
+        assertEquals("term_a", p.terminal());
+    }
+
+    /**
+     * fleetd #424 regression: the roster only answers THAT a pane is a live spawned member; config
+     * still decides WHAT that member's slot grants. A slot revoked after the bind must still demote
+     * the session on its very next request, exactly as it would for a pane with no roster entry at
+     * all — the roster's own ARCHITECT role must never be granted on its word alone.
+     *
+     * <p>{@code bind} refuses an unconfigured slot, so the revoked state can only be reached by
+     * binding while the slot is configured and then swapping the config out from under it, the way
+     * a live reload does.
+     */
+    @Test
+    void aRevokedArchitectSlotDemotesALiveSpawnedArchitectToWorker() {
+        FleetConfig.Fleet configured = new FleetConfig.Fleet(Map.of(),
+                Map.of("lead-designer", new FleetConfig.Slot("sonnet")), Map.of(), Map.of(), null);
+        java.util.concurrent.atomic.AtomicReference<FleetConfig.Fleet> live =
+                new java.util.concurrent.atomic.AtomicReference<>(configured);
+        MemberRegistry members = MemberRegistry.live(live::get);
+        assertTrue(members.bind("architect:lead-designer", "term_a"));
+
+        live.set(new FleetConfig.Fleet(Map.of(), Map.of(), Map.of(), Map.of(), null)); // slot revoked
+
+        // Setup controls: the slot is really gone from config, but the occupancy is still there —
+        // otherwise this test would pass for the wrong reason.
+        assertNull(members.roleForSlot("architect:lead-designer"), "setup control: the slot must be gone from config");
+        assertEquals("architect:lead-designer", members.snapshot().get("term_a"),
+                "setup control: the binding itself must still be there");
+
+        Principal p = CallerResolver.withLeadsAndMembers(workerIdentity(), false, null, Map::of,
+                        members, t -> "term_a".equals(t) ? MemberRole.ARCHITECT : null, Map::of)
+                .resolve("127.0.0.1", 42, null);
+
+        assertEquals(Role.WORKER, p.role(),
+                "a revoked slot must demote a live spawned architect on its very next request");
+    }
+
+    /** Criterion 3: a configured collaborator tab that is not a spawned member resolves COLLABORATOR. */
+    @Test
+    void aConfiguredCollaboratorTabResolvesToCollaboratorCarryingItsName() {
+        Principal p = CallerResolver.withLeadsAndMembers(workerIdentity(), false, null, Map::of,
+                        new MemberRegistry(null), t -> null, () -> Map.of("term_a", "ops"))
+                .resolve("127.0.0.1", 42, null);
+
+        assertEquals(Role.COLLABORATOR, p.role());
+        assertEquals("ops", p.name());
+        assertEquals("term_a", p.terminal());
+    }
+
+    /** Regression: an empty collaborator registry leaves every pane exactly as before. */
+    @Test
+    void anEmptyCollaboratorRegistryLeavesEveryPaneAsBefore() {
+        Principal p = CallerResolver.withLeadsAndMembers(workerIdentity(), false, null, Map::of,
+                        new MemberRegistry(null), t -> null, Map::of)
+                .resolve("127.0.0.1", 42, null);
+
+        assertEquals(Role.WORKER, p.role());
+        assertNull(p.name());
+    }
+
+    @Test
+    void describeNamesTheCollaborator() {
+        assertEquals("collaborator:ops", Principal.collaborator("ops", "term_a", 1).describe());
+    }
+
+    // ── fleetd #669 Unit D: knownLeadOrCollaborator() reads the same maps resolve() does ───────────
+
+    @Test
+    void knownLeadOrCollaboratorIsTrueForALeadTerminal() {
+        CallerResolver r = CallerResolver.withLeadsAndMembers(workerIdentity(), false, null,
+                () -> Map.of("term_lead", "opus-5.0"), new MemberRegistry(null), t -> null, Map::of);
+
+        assertTrue(r.knownLeadOrCollaborator().test("term_lead"));
+        assertFalse(r.knownLeadOrCollaborator().test("term_other"));
+    }
+
+    @Test
+    void knownLeadOrCollaboratorIsTrueForACollaboratorTerminal() {
+        CallerResolver r = CallerResolver.withLeadsAndMembers(workerIdentity(), false, null, Map::of,
+                new MemberRegistry(null), t -> null, () -> Map.of("term_collab", "ops"));
+
+        assertTrue(r.knownLeadOrCollaborator().test("term_collab"));
+        assertFalse(r.knownLeadOrCollaborator().test("term_other"));
+    }
+
+    @Test
+    void knownLeadOrCollaboratorIsFalseForASpawnedMembersTerminal() {
+        // The exact scenario a collaborator's SEND must never reach: a live spawned member's own
+        // terminal, which is neither a configured lead nor a configured collaborator.
+        CallerResolver r = CallerResolver.withLeadsAndMembers(workerIdentity(), false, null, Map::of,
+                new MemberRegistry(null), t -> "term_a".equals(t) ? MemberRole.DEV : null, Map::of);
+
+        assertFalse(r.knownLeadOrCollaborator().test("term_a"));
+    }
+
 }

fleetd/src/test/java/dev/ltms/fleet/config/ConfigRefTest.java

@@ -107,6 +107,8 @@ class ConfigRefTest {
 
         assertTrue(out.applied());
         assertTrue(out.deferred().isEmpty());
+        assertTrue(out.split().stream().noneMatch(s -> s.contains("fleet.collaborators")),
+                out.split().toString());
         assertEquals("new charter", ref.get().fleet().charterFor(
                 dev.ltms.fleet.peer.MemberRole.ARCHITECT));
     }
@@ -786,14 +788,100 @@ class ConfigRefTest {
         assertTrue(out.split().getFirst().startsWith("fleet:"), out.split().toString());
         assertTrue(out.split().getFirst().contains("restart"), out.split().toString());
         assertTrue(out.split().getFirst().contains("live"), out.split().toString());
+        assertTrue(out.split().stream().noneMatch(s -> s.contains("fleet.collaborators")),
+                out.split().toString());
         assertTrue(out.summary().contains("partially live"), out.summary());
         // The snapshot still carries the new value — the LeadTabScanner's identity map and
         // LeadLauncher's auto-launch are what wait for a restart; a reload rebuilds neither.
         assertEquals("lead: opus-b", ref.get().fleet().leaders().get("opus").tab());
     }
 
+    @Test
+    void addingAFleetCollaboratorIsReportedAsSplit(@TempDir Path dir) throws Exception {
+        assertCollaboratorChangeIsReported(dir, """
+                fleet:
+                  collaborators:
+                    alex:
+                      tab: "collaborator: alex"
+                """, "add a collaborator");
+    }
+
+    @Test
+    void removingAFleetCollaboratorIsReportedAsSplit(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("fleetd.yaml");
+        Files.writeString(f, yaml("""
+                fleet:
+                  collaborators:
+                    alex:
+                      tab: "collaborator: alex"
+                """));
+        ConfigRef ref = refFor(f);
+
+        Files.writeString(f, yaml("fleet: {}\n"));
+        assertCollaboratorSplit(ref.reload(), "remove a collaborator");
+    }
+
+    @Test
+    void changingAFleetCollaboratorTabIsReportedAsSplit(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("fleetd.yaml");
+        Files.writeString(f, yaml("""
+                fleet:
+                  collaborators:
+                    alex:
+                      tab: "collaborator: alex-a"
+                """));
+        ConfigRef ref = refFor(f);
+
+        Files.writeString(f, yaml("""
+                fleet:
+                  collaborators:
+                    alex:
+                      tab: "collaborator: alex-b"
+                """));
+        assertCollaboratorSplit(ref.reload(), "change a collaborator tab");
+    }
+
+    @Test
+    void unchangedFleetCollaboratorsProduceNoSplitReport(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("fleetd.yaml");
+        String config = yaml("""
+                fleet:
+                  collaborators:
+                    alex:
+                      tab: "collaborator: alex"
+                """);
+        Files.writeString(f, config);
+        ConfigRef ref = refFor(f);
+
+        Files.writeString(f, config);
+        ConfigRef.Outcome out = ref.reload();
+
+        assertTrue(out.applied());
+        assertTrue(out.split().isEmpty(), out.split().toString());
+    }
+
+    private static void assertCollaboratorChangeIsReported(Path dir, String changed, String action)
+            throws Exception {
+        Path f = dir.resolve("fleetd.yaml");
+        Files.writeString(f, yaml("fleet: {}\n"));
+        ConfigRef ref = refFor(f);
+
+        Files.writeString(f, yaml(changed));
+        assertCollaboratorSplit(ref.reload(), action);
+    }
+
+    private static void assertCollaboratorSplit(ConfigRef.Outcome out, String action) {
+        assertTrue(out.applied(), action);
+        assertTrue(out.deferred().isEmpty(), out.deferred().toString());
+        assertEquals(1, out.split().size(), out.split().toString());
+        String report = out.split().getFirst();
+        assertTrue(report.startsWith("fleet: fleet.collaborators"), report);
+        assertTrue(report.contains("read once at startup"), report);
+        assertTrue(report.contains("restart"), report);
+    }
+
     /**
-     * fleetd #333: {@code fleet.leaders} is the ONLY frozen part of {@code fleet:}. A reload that
+     * fleetd #333: {@code fleet.leaders} is a frozen part of {@code fleet:}. A reload that
      * changes {@code tabLabel} (or charters, or a role pool) without touching {@code fleet.leaders}
      * must stay fully hot with nothing reported — proving {@link ConfigRef#changedSplitKeys}
      * compares {@code fleet.leaders} specifically rather than the whole {@code Fleet} record, which

fleetd/src/test/java/dev/ltms/fleet/config/FleetConfigTest.java

@@ -850,7 +850,8 @@ class FleetConfigTest {
 
     /**
      * The hazard this guard closes: a pane-placed member lands inside the focused tab rather than
-     * its own, so it can land inside a lead's labelled tab and be read back as that lead.
+     * its own, so it can land inside a lead's labelled tab and, while its pane carries no entry in
+     * the spawned-member roster, be read back as that lead.
      */
     @Test
     void aPanePlacedProfileWithALeadTabRefusesToStart(@TempDir Path dir) throws Exception {
@@ -1000,6 +1001,274 @@ class FleetConfigTest {
                 "no primary.terminal pin ⇒ nothing registered, even with fleet.leaders configured");
     }
 
+    // ── fleetd #669: the collaborators registry ────────────────────────────────────────────────
+
+    /**
+     * {@code Fleet} is {@code @JsonIgnoreProperties(ignoreUnknown = true)}, so a config naming
+     * {@code fleet.collaborators.<name>.tab} loads with no exception whether or not the key is
+     * ever read into the object model. Asserting only "no exception" would pass both before and
+     * after the real fix, so this asserts the parsed value is actually reachable from the loaded
+     * {@code FleetConfig} — the one thing a vacuous "no exception" test cannot tell apart.
+     */
+    @Test
+    void collaboratorsBlockIsActuallyParsedNotSilentlyDropped(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("collaborators.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                fleet:
+                  collaborators:
+                    reviewer-alex:
+                      tab: "collab: alex"
+                """);
+
+        FleetConfig cfg = FleetConfig.load(f);
+        assertEquals("collab: alex", cfg.fleet().collaborators().get("reviewer-alex").tab());
+    }
+
+    /** A collaborator carries no field other than {@code tab}, so a blank one is meaningless. */
+    @Test
+    void aCollaboratorWithNoTabRefusesToStart(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("useless-collaborator.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                fleet:
+                  collaborators:
+                    ghost: {}
+                """);
+        FleetConfig cfg = FleetConfig.load(f);
+
+        IllegalStateException e = assertThrows(IllegalStateException.class, cfg::validateMembers);
+        assertTrue(e.getMessage().contains("ghost"), "the message must name the useless entry");
+        assertTrue(e.getMessage().contains("tab:"), "the message must say what is missing");
+    }
+
+    /** Control for {@link #aCollaboratorWithNoTabRefusesToStart}: a named tab loads cleanly. */
+    @Test
+    void aCollaboratorWithATabIsAllowed(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("named-collaborator.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                fleet:
+                  collaborators:
+                    reviewer-alex:
+                      tab: "collab: alex"
+                """);
+        FleetConfig cfg = FleetConfig.load(f);
+
+        assertDoesNotThrow(cfg::validateMembers);
+    }
+
+    /**
+     * fleetd #669: the fleet-wide {@code tabLabel} template can render as a collaborator tab, the
+     * same hazard {@link #aFleetTabLabelTemplateThatCanRenderAsALeadTabRefusesToStart} covers on
+     * the lead side. Drives the fleet-wide branch directly, with no profile override involved.
+     */
+    @Test
+    void aFleetTabLabelTemplateThatCanRenderAsACollaboratorTabRefusesToStart(@TempDir Path dir)
+            throws Exception {
+        Path f = dir.resolve("collide-template-collaborator.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                fleet:
+                  tabLabel: "al{profile}"
+                  collaborators:
+                    alex:
+                      tab: "alpha"
+                """);
+        FleetConfig cfg = FleetConfig.load(f);
+
+        IllegalStateException e =
+                assertThrows(IllegalStateException.class, cfg::validateLeadTabPrefixes);
+        assertTrue(e.getMessage().contains("fleet.tabLabel"));
+        assertTrue(e.getMessage().contains("alex"), "the message must name the offending collaborator");
+    }
+
+    /**
+     * A member tabLabel that can render as a configured collaborator tab is the same hazard as the
+     * lead case above — while its pane carries no entry in the spawned-member roster, a member
+     * labelled that way is read back as the collaborator.
+     */
+    @Test
+    void aProfileTabLabelOverrideMatchingACollaboratorTabRefusesToStart(@TempDir Path dir)
+            throws Exception {
+        Path f = dir.resolve("collide-collaborator.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                profiles:
+                  gx10:
+                    tabLabel: "collab-tab"
+                fleet:
+                  collaborators:
+                    alex:
+                      tab: "collab-tab"
+                """);
+        FleetConfig cfg = FleetConfig.load(f);
+
+        IllegalStateException e =
+                assertThrows(IllegalStateException.class, cfg::validateLeadTabPrefixes);
+        assertTrue(e.getMessage().contains("gx10"), "the message must name the offending profile");
+        assertTrue(e.getMessage().contains("collab-tab"), "the message must name the offending label");
+    }
+
+    /** Control: a profile tabLabel that cannot render as the collaborator tab is allowed. */
+    @Test
+    void aProfileTabLabelThatCannotRenderAsACollaboratorTabIsAllowed(@TempDir Path dir)
+            throws Exception {
+        Path f = dir.resolve("ok-collaborator.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                profiles:
+                  gx10:
+                    tabLabel: "worker-{profile}"
+                fleet:
+                  collaborators:
+                    alex:
+                      tab: "collab-tab"
+                """);
+        FleetConfig cfg = FleetConfig.load(f);
+
+        assertDoesNotThrow(cfg::validateLeadTabPrefixes);
+    }
+
+    /** fleetd #669: identity is matched on a collaborator's exact tab, so two sharing one are unreachable. */
+    @Test
+    void twoCollaboratorsSharingTheSameExactTabRefusesToStart(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("shared-collaborator-tab.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                fleet:
+                  collaborators:
+                    alex:
+                      tab: "shared tab"
+                    sam:
+                      tab: "Shared Tab"
+                """);
+        FleetConfig cfg = FleetConfig.load(f);
+
+        IllegalStateException e =
+                assertThrows(IllegalStateException.class, cfg::validateLeadTabPrefixes);
+        assertTrue(e.getMessage().contains("alex"), "the message must name one offending collaborator");
+        assertTrue(e.getMessage().contains("sam"), "the message must name the other offending collaborator");
+    }
+
+    /** Control for {@link #twoCollaboratorsSharingTheSameExactTabRefusesToStart}: distinct tabs load cleanly. */
+    @Test
+    void twoCollaboratorsWithDistinctExactTabsAreAllowed(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("distinct-collaborator-tabs.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                fleet:
+                  collaborators:
+                    alex:
+                      tab: "alex tab"
+                    sam:
+                      tab: "sam tab"
+                """);
+        FleetConfig cfg = FleetConfig.load(f);
+
+        assertDoesNotThrow(cfg::validateLeadTabPrefixes);
+    }
+
+    /**
+     * fleetd #669: a collaborator tab equal to a lead tab crosses a privilege boundary — the worst
+     * of the three new collisions, since only one of the two identities is ever found.
+     */
+    @Test
+    void aCollaboratorTabEqualToALeadTabRefusesToStart(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("lead-collaborator-collision.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                fleet:
+                  leaders:
+                    opus:
+                      tab: "shared tab"
+                  collaborators:
+                    alex:
+                      tab: "Shared Tab"
+                """);
+        FleetConfig cfg = FleetConfig.load(f);
+
+        IllegalStateException e =
+                assertThrows(IllegalStateException.class, cfg::validateLeadTabPrefixes);
+        assertTrue(e.getMessage().contains("opus"), "the message must name the offending lead");
+        assertTrue(e.getMessage().contains("alex"), "the message must name the offending collaborator");
+    }
+
+    /** Control for {@link #aCollaboratorTabEqualToALeadTabRefusesToStart}: distinct tabs load cleanly. */
+    @Test
+    void aLeadAndACollaboratorWithDistinctTabsAreAllowed(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("lead-collaborator-ok.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                fleet:
+                  leaders:
+                    opus:
+                      tab: "lead tab"
+                  collaborators:
+                    alex:
+                      tab: "collab tab"
+                """);
+        FleetConfig cfg = FleetConfig.load(f);
+
+        assertDoesNotThrow(cfg::validateLeadTabPrefixes);
+    }
+
+    /**
+     * fleetd #669: a pane-placed member can land in a collaborator's labelled tab exactly as it
+     * can land in a lead's — {@code validatePanePlacementAgainstLeadTabs()} must fire even when
+     * {@code fleet.leaders} is empty, which is the early-return the brief flagged as the bug.
+     */
+    @Test
+    void aPanePlacedProfileWithACollaboratorTabRefusesToStartEvenWithNoLeaders(@TempDir Path dir)
+            throws Exception {
+        Path f = dir.resolve("pane-hazard-collaborator.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                profiles:
+                  gx10:
+                    placement: pane
+                fleet:
+                  collaborators:
+                    alex:
+                      tab: "collab: alex"
+                """);
+        FleetConfig cfg = FleetConfig.load(f);
+
+        IllegalStateException e = assertThrows(IllegalStateException.class,
+                cfg::validatePanePlacementAgainstLeadTabs);
+        assertTrue(e.getMessage().contains("gx10"), "the message must name the offending profile");
+    }
+
+    /** Control: a pane-placed profile with no lead or collaborator tab configured is allowed. */
+    @Test
+    void aPanePlacedProfileWithNoLeaderOrCollaboratorTabIsAllowed(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("pane-no-tab-at-all.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                profiles:
+                  gx10:
+                    placement: pane
+                fleet:
+                  collaborators:
+                    alex: {}
+                """);
+
+        assertDoesNotThrow(() -> FleetConfig.load(f).validatePanePlacementAgainstLeadTabs(),
+                "a collaborator with no tab feeds nothing into the scanner, so pane placement is safe");
+    }
+
     // ── CB-548: the architects registry ────────────────────────────────────────────────────────
 
     @Test
@@ -1272,6 +1541,60 @@ class FleetConfigTest {
         assertEquals(Set.of("sonnet"), cfg.fleet().pool(MemberRole.REVIEWER).keySet());
     }
 
+    /**
+     * A duplicated name in {@code fleet.collaborators} is refused at parse time, like any other
+     * {@code fleet:} pool. See {@link #duplicateSlotNamesInOnePoolAreRejectedAtParseTime}.
+     */
+    @Test
+    void duplicateCollaboratorNamesAreRejectedAtParseTime(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("collaborator-dup.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                fleet:
+                  collaborators:
+                    alex:
+                      tab: "collab: alex"
+                    alex:
+                      tab: "collab: alex, second"
+                """);
+
+        IllegalStateException e =
+                assertThrows(IllegalStateException.class, () -> FleetConfig.load(f));
+        assertTrue(e.getMessage().contains("alex"),
+                "the refusal names the duplicated entry, was: " + e.getMessage());
+        assertTrue(e.getMessage().contains("fleet.collaborators"),
+                "the refusal names the pool the duplicate is in, was: " + e.getMessage());
+    }
+
+    /**
+     * Control for {@link #duplicateCollaboratorNamesAreRejectedAtParseTime}: the same name reused
+     * across the collaborators registry and a member role pool is the role × profile matrix doing
+     * its job in the other pool, not a mistake — only a repeat within one pool loses an entry.
+     */
+    @Test
+    void theSameNameInCollaboratorsAndAnotherPoolIsNotADuplicate(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("collaborator-cross-pool.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                profiles:
+                  sonnet:
+                    baseUrl: http://gx10.gw:8000
+                fleet:
+                  architects:
+                    alex:
+                      profile: sonnet
+                  collaborators:
+                    alex:
+                      tab: "collab: alex"
+                """);
+
+        FleetConfig cfg = assertDoesNotThrow(() -> FleetConfig.load(f));
+        assertEquals(Set.of("alex"), cfg.fleet().pool(MemberRole.ARCHITECT).keySet());
+        assertEquals(Set.of("alex"), cfg.fleet().collaborators().keySet());
+    }
+
     @Test
     void duplicateKeysOutsideTheFleetPoolsAreUnaffected(@TempDir Path dir) throws Exception {
         // The duplicate check is scoped to the fleet pools — a duplicate elsewhere is not this

fleetd/src/test/java/dev/ltms/fleet/herdr/HerdrRouterTest.java

@@ -2,6 +2,8 @@ package dev.ltms.fleet.herdr;
 
 import org.junit.jupiter.api.Test;
 
+import java.util.Map;
+
 import static org.junit.jupiter.api.Assertions.assertSame;
 import static org.junit.jupiter.api.Assertions.assertNotSame;
 
@@ -28,4 +30,44 @@ class HerdrRouterTest {
         assertSame(router.leadAgents(), router.agentsFor("lead"));
         assertSame(router.memberAgents(), router.agentsFor("member"));
     }
+
+    /**
+     * fleetd #669 Unit E. The predicate shape here is exactly what {@code FleetdAssembly} builds:
+     * true when the terminal is a known lead OR a known collaborator. Two distinct clients are
+     * required — with one shared client {@code agentsFor} would return the same object regardless
+     * of the predicate's answer, and this assertion would pass whether or not the collaborator map
+     * was ever consulted.
+     */
+    @Test
+    void collaboratorTerminalRoutesToTheLeadDaemon() {
+        FakeHerdr lead = new FakeHerdr();
+        FakeHerdr member = new FakeHerdr();
+        Map<String, String> leads = Map.of("term_lead", "primary");
+        Map<String, String> collaborators = Map.of("term_collab", "reviewer-alex");
+        HerdrRouter router = new HerdrRouter(lead, member,
+                id -> leads.containsKey(id) || collaborators.containsKey(id));
+
+        assertSame(router.leadAgents(), router.agentsFor("term_collab"),
+                "a configured collaborator's terminal must route to the LEAD daemon, not the member "
+                        + "one — its pane is opened by a person, exactly like a lead's");
+    }
+
+    /**
+     * Companion to {@link #collaboratorTerminalRoutesToTheLeadDaemon}: a terminal that is neither a
+     * known lead nor a known collaborator must still route to the member daemon. Without this, a
+     * predicate of {@code _ -> true} would also pass the test above.
+     */
+    @Test
+    void terminalInNeitherMapStillRoutesToTheMemberDaemon() {
+        FakeHerdr lead = new FakeHerdr();
+        FakeHerdr member = new FakeHerdr();
+        Map<String, String> leads = Map.of("term_lead", "primary");
+        Map<String, String> collaborators = Map.of("term_collab", "reviewer-alex");
+        HerdrRouter router = new HerdrRouter(lead, member,
+                id -> leads.containsKey(id) || collaborators.containsKey(id));
+
+        assertSame(router.memberAgents(), router.agentsFor("term_worker"),
+                "a terminal absent from both maps must stay on the member daemon — the fix widens "
+                        + "the predicate, it does not make it unconditionally true");
+    }
 }

fleetd/src/test/java/dev/ltms/fleet/herdr/LeadTabScannerTest.java

@@ -163,6 +163,13 @@ class LeadTabScannerTest {
         return new LeadTabScanner(herdr, tabToName, Set.of("fleetd-workers"), TTL, clock::get);
     }
 
+    private LeadTabScanner scannerWithCollaborators(TopologyHerdr herdr, Map<String, String> tabToName,
+                                                     Map<String, String> collaboratorTabToName,
+                                                     AtomicLong clock) {
+        return new LeadTabScanner(herdr, tabToName, collaboratorTabToName,
+                Set.of("fleetd-workers"), TTL, clock::get);
+    }
+
     @Test
     void everyConfiguredTabBecomesALeadNamedByItsEntry() {
         Map<String, String> leads = scanner(twoLeads(), twoLeadsConfigured(), new AtomicLong()).get();
@@ -198,9 +205,12 @@ class LeadTabScannerTest {
     }
 
     /**
-     * The guard that matters: fleetd labels its own worker tabs, so if a worker space were scanned
-     * a naming accident would promote the fleet. The exclusion is by workspace, not by hoping the
-     * worker template never collides.
+     * Covers the {@code excludedWorkspaceLabels} parameter: a tab in an excluded workspace is never
+     * matched, whatever its label. Production always constructs this class with an empty set (CB-558,
+     * {@code FleetdAssembly}), so this parameter plays no part in the live guard against a worker
+     * tab being mistaken for a lead — that guard is {@code CallerResolver} asking the live
+     * spawned-member roster before any tab map. This test exists because the parameter still exists
+     * and is worth covering on its own terms.
      */
     @Test
     void aTabInAWorkerSpaceIsNeverALeadEvenWhenItsLabelMatches() {
@@ -212,6 +222,29 @@ class LeadTabScannerTest {
         assertFalse(scanner(herdr, tabToName, new AtomicLong()).get().containsKey("term_impostor"));
     }
 
+    /**
+     * The shipped shape (CB-558, {@code FleetdAssembly}): production always constructs this class
+     * with an empty {@code excludedWorkspaceLabels}, and a lead's {@code workspace:} default is the
+     * same shared {@code "fleet"} space the members use. A lead tab is still found when it sits in
+     * the exact same workspace as a member-labelled tab — the scanner tells them apart by the exact
+     * tab label, not by which workspace either one is in.
+     */
+    @Test
+    void aLeadIsDiscoveredWhenItsWorkspaceIsTheSameAsTheMemberWorkspace() {
+        TopologyHerdr herdr = new TopologyHerdr()
+                .workspace("w1", "fleet")
+                .tab("w1:t1", "w1", "lead: opus-5.0")
+                .tab("w1:t2", "w1", "worker: gx10 #1")
+                .pane("w1:p1", "w1:t1", "term_opus")
+                .pane("w1:p2", "w1:t2", "term_worker");
+        LeadTabScanner s = new LeadTabScanner(herdr, Map.of("lead: opus-5.0", "opus-5.0"),
+                Set.of(), TTL, new AtomicLong()::get);
+
+        assertEquals("opus-5.0", s.get().get("term_opus"),
+                "a lead sharing the members' workspace is still discovered — the label, not the "
+                        + "workspace, is what matches it");
+    }
+
     @Test
     void aLabelWithNoConfiguredEntryIsIgnored() {
         TopologyHerdr herdr = new TopologyHerdr().workspace("w1", "main")
@@ -464,4 +497,75 @@ class LeadTabScannerTest {
 
         assertEquals(afterFirst, herdr.calls, "the failure path must be rate-limited too");
     }
+
+    // ── fleetd #669 Unit D: a collaborator tab is matched the same way as a lead tab, one pass ─────
+
+    @Test
+    void aConfiguredCollaboratorTabIsReportedByCollaboratorsNotByGet() {
+        TopologyHerdr herdr = new TopologyHerdr()
+                .workspace("w1", "main")
+                .tab("w1:t1", "w1", "collab: ops")
+                .pane("w1:p1", "w1:t1", "term_ops");
+        LeadTabScanner s = scannerWithCollaborators(herdr, Map.of(), Map.of("collab: ops", "ops"),
+                new AtomicLong());
+
+        assertEquals(Map.of("term_ops", "ops"), s.collaborators(),
+                "a collaborator tab is matched exactly like a lead tab");
+        assertEquals(Map.of(), s.get(), "a collaborator tab must never also appear as a lead");
+    }
+
+    /**
+     * Criterion 4, scanner level: a collaborator tab that is labelled but runs no agent is not
+     * reported — the same #359 liveness cross-check a lead tab gets.
+     */
+    @Test
+    void aDeadCollaboratorTabIsNotReported() {
+        TopologyHerdr herdr = new TopologyHerdr()
+                .workspace("w1", "main")
+                .tab("w1:t1", "w1", "collab: ops")
+                .pane("w1:p1", "w1:t1", "term_ops")
+                .deadAgent("w1:t1");
+        LeadTabScanner s = scannerWithCollaborators(herdr, Map.of(), Map.of("collab: ops", "ops"),
+                new AtomicLong());
+
+        assertFalse(s.collaborators().containsKey("term_ops"),
+                "a dead collaborator tab must never resolve as a live collaborator");
+    }
+
+    /**
+     * Both kinds are matched in a single pass over the same tab list — not a second scanner, not a
+     * second scan. Proven by herdr call count: scanning one lead tab and one collaborator tab in the
+     * same instance costs exactly as many calls as scanning two lead tabs in {@link #twoLeads()}.
+     */
+    @Test
+    void leadsAndCollaboratorsAreMatchedInOnePassOverTheSameScan() {
+        TopologyHerdr oneOfEach = new TopologyHerdr()
+                .workspace("w1", "main")
+                .tab("w1:t1", "w1", "lead: opus-5.0")
+                .tab("w1:t2", "w1", "collab: ops")
+                .pane("w1:p1", "w1:t1", "term_opus")
+                .pane("w1:p2", "w1:t2", "term_ops");
+        LeadTabScanner s = scannerWithCollaborators(oneOfEach, Map.of("lead: opus-5.0", "opus-5.0"),
+                Map.of("collab: ops", "ops"), new AtomicLong());
+
+        assertEquals(Map.of("term_opus", "opus-5.0"), s.get());
+        assertEquals(Map.of("term_ops", "ops"), s.collaborators());
+
+        TopologyHerdr twoLeadsBaseline = twoLeads();
+        scanner(twoLeadsBaseline, twoLeadsConfigured(), new AtomicLong()).get();
+
+        assertEquals(twoLeadsBaseline.calls, oneOfEach.calls,
+                "one lead tab + one collaborator tab must cost exactly as many herdr calls as two "
+                        + "lead tabs — proof this is one pass, not a second scan");
+    }
+
+    /** Regression: with no collaborators configured, every existing lead-only behaviour is unchanged. */
+    @Test
+    void anEmptyCollaboratorMapLeavesCollaboratorsEmptyAndGetUnaffected() {
+        LeadTabScanner s = scannerWithCollaborators(twoLeads(), twoLeadsConfigured(), Map.of(),
+                new AtomicLong());
+
+        assertEquals(Map.of(), s.collaborators());
+        assertEquals(Map.of("term_opus", "opus-5.0", "term_gpt", "gpt-sol-5.6"), s.get());
+    }
 }

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

@@ -63,6 +63,17 @@ class FleetMcpAuthzTest {
 
     /** A fully wired FleetMcp on fakes — constructing it is itself part of what is under test. */
     private FleetMcp mcp(boolean enforce) {
+        ConnectionIdentity identity = new ConnectionIdentity(new PaneLocator(herdr), _ -> 999_999);
+        return mcp(enforce, CallerResolver.withLeadsAndMembers(identity, false, null,
+                Map::of, new MemberRegistry(null)));
+    }
+
+    /**
+     * As {@link #mcp(boolean)}, with an explicit {@link CallerResolver} — so a test can wire known
+     * leads/collaborators and drive {@code denyFor}'s real {@code knownLeadOrCollaborator()}
+     * classifier instead of the default empty one.
+     */
+    private FleetMcp mcp(boolean enforce, CallerResolver callers) {
         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);
@@ -83,9 +94,7 @@ class FleetMcpAuthzTest {
         // 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),
-                CallerResolver.withLeadsAndMembers(identity, false, null,
-                Map::of, new MemberRegistry(null)),
+                new PrimaryRegistry(null), callers,
                 enforce ? FleetMcp.AuthorizationMode.ENFORCED : FleetMcp.AuthorizationMode.UNENFORCED,
                 metrics, FleetMcp.CapacitySource.none(), new FleetMcp.HealthCoverageSource(() -> "off"),
                 FleetMcp.QuarantineSource.none(), null, FleetMcp.OutageSource.none(),
@@ -97,6 +106,7 @@ 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 +236,39 @@ 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());
+    }
+
+    /**
+     * fleetd #669 Unit D: wires a real {@link CallerResolver} with a known lead and a known
+     * collaborator tab, and leaves a spawned member's own terminal recognised by neither map — so a
+     * collaborator's SEND reaches both named peers and is refused for the spawned member's terminal,
+     * over MCP's {@code denyFor}.
+     */
+    @Test
+    void aCollaboratorMaySendToAKnownLeadOrCollaboratorButNotToASpawnedMembersTerminal() {
+        ConnectionIdentity identity = new ConnectionIdentity(new PaneLocator(herdr), _ -> 999_999);
+        CallerResolver callers = CallerResolver.withLeadsAndMembers(identity, false, null,
+                () -> Map.of("term_lead_known", "lead-x"), new MemberRegistry(null),
+                t -> null, () -> Map.of("term_collab_known", "ops2"));
+        FleetMcp m = mcp(true, callers);
+
+        assertNull(m.denyFor(COLLABORATOR, Authz.Action.SEND, "term_lead_known"));
+        assertNull(m.denyFor(COLLABORATOR, Authz.Action.SEND, "term_collab_known"));
+        assertNotNull(m.denyFor(COLLABORATOR, Authz.Action.SEND, "term_a"),
+                "a spawned member's own terminal must stay unreachable, even once the classifier is real");
+    }
+
     @Test
     void theLegacyConstructorLeavesTheGateOpen() {
         // The 22 pre-existing FleetMcpTest cases rely on no authorization being enforced.
@@ -323,6 +366,58 @@ class FleetMcpAuthzTest {
                         + "calling, not pass a literal boolean -- found: " + trailing);
     }
 
+    // --- fleetd #703: who may see fleet_list's collaborators array -------------------------------
+
+    /**
+     * fleetd #703: {@link FleetMcp#collaboratorsVisibleTo} is the whole policy decision for
+     * {@code fleet_list}'s {@code collaborators} array. Visible to exactly the roles that may
+     * {@code SEND} to a named peer -- the primary, an architect, and a collaborator itself -- never
+     * a worker, which holds {@code READ} but can never {@code SEND} to a collaborator, and never an
+     * anonymous caller.
+     */
+    @Test
+    void onlyPrimaryArchitectAndCollaboratorMaySeeTheCollaboratorsArray() {
+        assertTrue(FleetMcp.collaboratorsVisibleTo(PRIMARY), "the primary must see the collaborators array");
+        assertTrue(FleetMcp.collaboratorsVisibleTo(ARCH_DESIGN), "an architect must see the collaborators array");
+        assertTrue(FleetMcp.collaboratorsVisibleTo(COLLABORATOR), "a collaborator must see its own peer roster");
+        assertFalse(FleetMcp.collaboratorsVisibleTo(WORKER_A),
+                "a worker holds READ but can never SEND to a collaborator, so it must not see the array");
+        assertFalse(FleetMcp.collaboratorsVisibleTo(ANON), "authenticated as nothing must not see it either");
+    }
+
+    /**
+     * fleetd #703, same reasoning as {@link #theFleetListHandlerActuallyConsultsCoordinatorVisibleTo}:
+     * the predicate above can be perfectly correct while the one production call site never asks it.
+     * This reads {@code FleetMcp.java}'s own source and asserts the {@code fleet_list} handler's
+     * {@code listFleet(...)} call both threads {@code callers.collaborators()} into the payload and
+     * asks {@code collaboratorsVisibleTo(principal(exchange))} for the visibility flag, rather than a
+     * literal boolean or an empty map.
+     */
+    @Test
+    void theFleetListHandlerActuallyConsultsCollaboratorsVisibleTo() throws Exception {
+        String source = Files.readString(MCP_SOURCE);
+
+        int start = source.indexOf("listHandler =");
+        assertTrue(start >= 0, "could not find the fleet_list handler (listHandler) in " + MCP_SOURCE
+                + " -- the scrape has stopped matching, fix the anchor before trusting this test");
+        int end = source.indexOf("stopHandler =", start);
+        assertTrue(end > start, "could not find the handler declared after listHandler to bound the scrape");
+        String handlerBlock = source.substring(start, end);
+
+        // CONTROL: the block we scraped really does contain a call to listFleet(...) -- if this
+        // fails, the anchors above moved and the assertions below would otherwise pass on nothing.
+        assertTrue(handlerBlock.contains("listFleet("),
+                "control failed: the scraped listHandler block contains no listFleet( call at all -- "
+                        + "the anchors have drifted, this test is not testing what it claims to");
+
+        assertTrue(handlerBlock.contains("callers.collaborators()"),
+                "the fleet_list handler must thread callers.collaborators() into listFleet(...), not an "
+                        + "empty or literal map -- block: " + handlerBlock);
+        assertTrue(handlerBlock.contains("collaboratorsVisibleTo(principal(exchange))"),
+                "the fleet_list handler must ask collaboratorsVisibleTo(principal(exchange)) who is "
+                        + "calling, not pass a literal boolean -- block: " + handlerBlock);
+    }
+
     // --- which action each tool hands the gate (fleetd #272) ------------------------------------
 
     /**

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

@@ -121,6 +121,7 @@ class FleetMcpLeadContextGaugeWiringTest {
                 FleetMcp.CapacitySource.none(), new FleetMcp.HealthCoverageSource(() -> "off"),
                 FleetMcp.LoopHealthSource.none(), FleetMcp.QuarantineSource.none(), FleetMcp.OutageSource.none(),
                 FleetMcp.LeadSeatSource.none(), contextGauge, leadConfigDirs,
-                Map.of(LEAD_TERMINAL, LEAD_NAME), LEAD_TERMINAL, FleetMcp.CoordinationSource.none(), false);
+                Map.of(LEAD_TERMINAL, LEAD_NAME), LEAD_TERMINAL, Map.of(), false,
+                FleetMcp.CoordinationSource.none(), false);
     }
 }

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

@@ -10,6 +10,7 @@ import dev.ltms.fleet.herdr.AgentControl;
 import dev.ltms.fleet.herdr.AgentStatus;
 import dev.ltms.fleet.herdr.FakeHerdr;
 import dev.ltms.fleet.inject.LoopWatchdog;
+import dev.ltms.fleet.lead.LeadContextGauge;
 import dev.ltms.fleet.herdr.PaneLocator;
 import dev.ltms.fleet.herdr.WorkspaceControl;
 import dev.ltms.fleet.inject.Injector;
@@ -879,6 +880,83 @@ class FleetMcpTest {
         assertTrue(out.contains("x".repeat(80) + "…"), "expected an 80-char preview with an ellipsis: " + out);
     }
 
+    // --- fleetd #703: fleet_list's collaborators array -------------------------------------------
+
+    /** Calls the canonical {@code listFleet} overload directly, so a test can set the collaborators
+     * payload and its visibility independently of a real {@code Principal} / MCP exchange. */
+    private static McpSchema.CallToolResult listFleetWithCollaborators(FakeHerdr h,
+            Map<String, String> collaborators, boolean collaboratorsVisible) {
+        SessionManager sessions = new SessionManager(workerService(h, "http://gx00.gw:8000", Set.of("gx00.gw")));
+        return FleetMcp.listFleet(
+                workerService(h, "http://gx00.gw:8000", Set.of("gx00.gw")), sessions, null,
+                FleetMcp.CapacitySource.none(), new FleetMcp.HealthCoverageSource(() -> "off"),
+                FleetMcp.LoopHealthSource.none(), FleetMcp.QuarantineSource.none(), FleetMcp.OutageSource.none(),
+                FleetMcp.LeadSeatSource.none(), new LeadContextGauge(), FleetMcp.LeadConfigDirSource.none(),
+                Map.of(), "", collaborators, collaboratorsVisible,
+                FleetMcp.CoordinationSource.none(), false);
+    }
+
+    /**
+     * fleetd #703 acceptance A: a visible caller with one configured collaborator gets a
+     * {@code collaborators} row whose key ({@code CallerResolver.collaborators()}'s
+     * {@code terminal_id -> name} entry) lands as that row's {@code sessionId}, and {@code leads}/
+     * {@code members} are unaffected by the new key.
+     */
+    @Test
+    void listReportsACollaboratorsRowKeyedByTheCollaboratorsTerminalId() {
+        FakeHerdr h = new FakeHerdr();
+        String out = textOf(listFleetWithCollaborators(h, Map.of("term_collab", "ops"), true));
+
+        assertTrue(out.contains("\"collaborators\":["), out);
+        assertTrue(out.contains("\"name\":\"ops\""), out);
+        assertTrue(out.contains("\"sessionId\":\"term_collab\""), out);
+        assertTrue(out.contains("\"leads\":[]"), out);
+        assertTrue(out.contains("\"members\":[]"), out);
+    }
+
+    /**
+     * fleetd #703 acceptance A, control half: with no collaborator configured, the key is absent
+     * (caller cannot see it) or an empty array (caller can), and {@code leads}/{@code members} are
+     * unchanged either way.
+     */
+    @Test
+    void listOmitsOrEmptiesCollaboratorsWhenNoneAreConfigured() {
+        FakeHerdr h = new FakeHerdr();
+
+        String visibleButEmpty = textOf(listFleetWithCollaborators(h, Map.of(), true));
+        assertTrue(visibleButEmpty.contains("\"collaborators\":[]"), visibleButEmpty);
+        assertTrue(visibleButEmpty.contains("\"leads\":[]"), visibleButEmpty);
+        assertTrue(visibleButEmpty.contains("\"members\":[]"), visibleButEmpty);
+
+        String notVisible = textOf(listFleetWithCollaborators(h, Map.of(), false));
+        assertFalse(notVisible.contains("\"collaborators\""), notVisible);
+        assertTrue(notVisible.contains("\"leads\":[]"), notVisible);
+        assertTrue(notVisible.contains("\"members\":[]"), notVisible);
+    }
+
+    /**
+     * fleetd #703 acceptance B: a worker must not see the {@code collaborators} array at all, while
+     * an architect -- a role that also holds READ, same as a worker -- does see it. Both halves are
+     * asserted: a test that only checked the worker-hidden half would pass even if the feature were
+     * never wired up for anyone.
+     */
+    @Test
+    void listOmitsCollaboratorsForAWorkerAndIncludesThemForAnArchitect() {
+        FakeHerdr h = new FakeHerdr();
+        Map<String, String> collaborators = Map.of("term_collab", "ops");
+
+        String asWorker = textOf(listFleetWithCollaborators(h, collaborators,
+                FleetMcp.collaboratorsVisibleTo(Principal.worker("term_w", 1))));
+        assertFalse(asWorker.contains("\"collaborators\""),
+                "a worker must not see the collaborators array: " + asWorker);
+
+        String asArchitect = textOf(listFleetWithCollaborators(h, collaborators,
+                FleetMcp.collaboratorsVisibleTo(Principal.architect("design", "term_arch", 2))));
+        assertTrue(asArchitect.contains("\"collaborators\":["),
+                "an architect must see the collaborators array: " + asArchitect);
+        assertTrue(asArchitect.contains("\"sessionId\":\"term_collab\""), asArchitect);
+    }
+
     /**
      * fleetd #421: {@code mailbox.pending} counts only broker-ready messages, so a blocked lead's
      * normal, healthy state is {@code "pending": 0} next to a non-empty {@code held[]} — which
@@ -1837,6 +1915,32 @@ 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 +203,74 @@ class FleetAppAuthTest {
         }
     }
 
+    /**
+     * {@code permitsFor} is the exact decision {@link FleetApp#allow} makes, passing the real
+     * production classifier rather than a test-supplied one — built from an empty {@link
+     * CallerResolver}, so no terminal is recognised as a configured lead or collaborator and a
+     * collaborator's SEND is refused through the REST gate.
+     */
+    @Test
+    void aCollaboratorMayNotSendOverRestWithTheRealProductionClassifier() {
+        ConnectionIdentity identity = new ConnectionIdentity(new PaneLocator(new FakeHerdr()), _ -> 700L);
+        CallerResolver callers = CallerResolver.withLeadsAndMembers(identity, false, null,
+                Map::of, new MemberRegistry(null));
+        Principal collaborator = Principal.collaborator("ops", "term_collab", 700);
+        assertFalse(FleetApp.permitsFor(collaborator, Authz.Action.SEND, "term_lead",
+                        callers.knownLeadOrCollaborator()),
+                "no terminal is recognised as a lead or collaborator yet");
+    }
+
+    /**
+     * fleetd #669 Unit D: wires a real {@link CallerResolver} with a known lead and a known
+     * collaborator tab, and a spawned member's own terminal recognised by neither map. A
+     * collaborator's SEND reaches the known lead and the known collaborator, and is refused for the
+     * spawned member's terminal — over the REST route, not just the unit-level classifier, so a
+     * test covering only MCP cannot leave this route open.
+     */
+    @Test
+    void aCollaboratorMaySendToAKnownLeadOrCollaboratorButNotToASpawnedMembersTerminalOverRest() throws Exception {
+        int port = startWithRealClassifier(FakeHerdr.WORKER_PID,
+                Map.of("term_lead_known", "lead-x"), Map.of("term_a", "ops2"));
+
+        HttpResponse<String> toLead = send(port, "POST", "/sessions/term_lead_known/message",
+                "{\"content\":\"hi\",\"wait\":false}", null);
+        assertEquals(202, toLead.statusCode(), toLead.body());
+
+        HttpResponse<String> toSpawnedMembersTerminal = send(port, "POST", "/sessions/term_worker/message",
+                "{\"content\":\"hi\",\"wait\":false}", null);
+        assertEquals(403, toSpawnedMembersTerminal.statusCode(), toSpawnedMembersTerminal.body());
+    }
+
+    /**
+     * As {@link #start}, but with explicit lead/collaborator maps and no spawned-member roster, so
+     * a test can wire the real {@link CallerResolver#knownLeadOrCollaborator()} classifier instead
+     * of the default empty one.
+     */
+    private int startWithRealClassifier(long pid, Map<String, String> leadTerminals,
+                                        Map<String, String> collaboratorTerminals) {
+        FakeHerdr herdr = new FakeHerdr();
+        FleetConfig.Profile wcfg = new FleetConfig.Profile(
+                "ltms-local", "http://gx00.gw:8000", "coder", null, "FLEETD_WORKER_TOKEN", null,
+                "tab", "fleetd-workers", "worker: {profile} #{n}", null, null, null);
+        AgentControl agents = new AgentControl(herdr);
+        ClaudeCodeLauncher workers = new ClaudeCodeLauncher(
+                agents, new WorkspaceControl(herdr), new SubscriptionGuard(Set.of("gx00.gw")),
+                Map.of(wcfg.profile(), wcfg), wcfg.profile(),
+                k -> "FLEETD_WORKER_TOKEN".equals(k) ? "tok-abc" : null);
+        SessionManager sessions = new SessionManager(workers, new FakeWorktrees());
+        Injector injector = new Injector(agents);
+        MessageService messages = new MessageService(agents, injector, new Rendezvous());
+
+        ConnectionIdentity identity = new ConnectionIdentity(new PaneLocator(herdr), _ -> pid);
+        CallerResolver callers = CallerResolver.withLeadsAndMembers(identity, false, null,
+                () -> leadTerminals, new MemberRegistry(null), t -> null, () -> collaboratorTerminals);
+        metrics = FleetMetrics.create(sessions, new dev.ltms.fleet.msg.InMemoryReplyInbox());
+
+        app = new FleetApp(herdr, workers, sessions, messages, sessions.asPresence(), null,
+                callers, metrics).build().start("127.0.0.1", 0);
+        return app.port();
+    }
+
     // --- loopback-trust: the caller is the primary -------------------------------------------
 
     @Test