Merge PR #708: fleetd #669 — fleetd.example.yaml promised a defence that is not wired

The example file said two things stop the tab-name convention from becoming a
way to claim leadership, and named workspace exclusion as the first. Production
builds the scanner with an empty excludedWorkspaceLabels, so that defence does
not exist. It now names the two that do: the startup refusal of a colliding
tabPrefix/tabLabel, and CallerResolver asking the live spawned-member roster
before any tab map.

It also said a lead's workspace default is "leads" and must not be a member
workspace. The default is "fleet", the same space the members use, so that
advice was against the shipped shape.

Adds the test nobody wrote: a lead is still discovered when its workspace is
the member workspace, with an empty exclusion set. Corrects a test javadoc that
called itself the guard that matters while covering a parameter production never
passes.

mvn clean install: exit 0, BUILD SUCCESS, Tests run: 2000, Failures: 0.

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:

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/herdr/LeadTabScannerTest.java

@@ -205,9 +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() {
@@ -219,6 +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")