fleetd #661: add the pane-placement case to the validateAll reachability enumeration

validateAllReachesEveryOneOfTodaysSixValidators only covered six of
the eight real validators; the new validator was reachability-tested
only from FleetConfigTest, in a different file from the one whose job
is to enumerate every validateAll-reachability case.

Add the pane-placement case to the enumeration, rename the method to
drop the hardcoded count (validateAllReachesEveryOneOfTodaysRealValidators),
and correct the surrounding claims to say seven of eight, naming
validateLeadRollover as the one case still missing (fleetd #668, not
fixed here).

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

@@ -2688,9 +2688,10 @@ public record FleetConfig(
      * tab labels — every member gets one rendered into its tab. Choose a lead {@code tabPrefix} that
      * a member template matches and the daemon starts labelling its own members as leads, promoting
      * the entire fleet to {@link dev.ltms.fleet.auth.Role#PRIMARY} with no message and no diff.
-     * The member-space exclusion in {@link dev.ltms.fleet.herdr.LeadTabScanner} already blocks the
-     * realistic path, but defence that depends on one workspace label holding is not defence enough
-     * for a privilege boundary.
+     * {@link #validatePanePlacementAgainstLeadTabs()} is the check that stops a pane-placed member
+     * from landing inside a lead's tab in the first place; this check is a second, independent
+     * guard that catches the hazard even when every profile places members correctly, by refusing
+     * a label that a scan would still misread as a lead.
      *
      * <p>CB-557 shrank this check rather than removing it. The default template is
      * {@code "{role}: {profile} #{n}"} and {@code {role}} comes from a closed enum, so a
@@ -2737,6 +2738,45 @@ public record FleetConfig(
                 + "lead tabs cannot be confused.");
     }
 
+    /**
+     * 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.
+     *
+     * <p>Only a leader 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}
+     */
+    public void validatePanePlacementAgainstLeadTabs() {
+        if (fleet == null || fleet.leaders().isEmpty()) {
+            return;
+        }
+        boolean anyLeaderHasTab = fleet.leaders().values().stream()
+                .anyMatch(leader -> leader != null && leader.tab() != null && !leader.tab().isBlank());
+        if (!anyLeaderHasTab) {
+            return;
+        }
+        List<String> bad = new ArrayList<>();
+        profiles().entrySet().stream()
+                .filter(e -> !e.getValue().tabPlacement())
+                .map(Map.Entry::getKey)
+                .sorted()
+                .forEach(bad::add);
+        if (bad.isEmpty()) {
+            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.");
+    }
+
     /**
      * Reject a present {@code leadRollover:} block with no (or a blank) {@code handoverPath}
      * (fleetd #480). There is no sane non-null default for an operator-specific file path, unlike

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

@@ -37,8 +37,11 @@ import java.util.function.Supplier;
  * <p><strong>Direction of trust.</strong> The label names the lead; it never <em>grants</em>
  * anything a pane could take for itself. Three properties keep that honest:
  * <ol>
- *   <li>Worker spaces are excluded wholesale ({@code excludedWorkspaceLabels}), so a worker cannot
- *       become a lead by being placed — as a split, say — inside a matching tab.</li>
+ *   <li>{@code excludedWorkspaceLabels} can filter a workspace out of the scan, but this class does
+ *       not by itself stop a worker from landing inside a matching tab — a caller may pass an empty
+ *       set, and the daemon does. The guard against that is {@code
+ *       FleetConfig.validatePanePlacementAgainstLeadTabs}: it refuses, at startup, any profile that
+ *       places members by pane while a lead names a tab.</li>
  *   <li>A worker cannot rename a tab: {@code tab.rename} is reachable only through
  *       {@link WorkspaceControl}, which no {@code fleet_*} tool exposes. The label is writable by
  *       the human at the terminal and by nobody the bridge is defending against.</li>

fleetd/src/main/java/dev/ltms/fleet/lead/LeadLauncher.java

@@ -201,8 +201,8 @@ public final class LeadLauncher {
     /**
      * How many live leads exist per configured name, and which of that name's labelled tabs are
      * <em>not</em> live: a running agent in a tab labelled with that lead's exact {@code tab}
-     * (CB-579). Member workspaces are excluded, exactly as the scanner excludes them: a member must
-     * not be counted as a lead because it happens to sit in a matching tab.
+     * (CB-579). A member sitting in the same shared workspace is not counted as a lead because its
+     * tab carries a different label, not because any workspace is excluded from this count.
      *
      * <p>There used to be a second path here — a running agent on the terminal a
      * {@code fleet.leaders.<name>.terminal} pin named, for a lead opened and pinned by hand. That

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

@@ -765,6 +765,92 @@ class FleetConfigTest {
                 "a label that collides with a convention nobody reads is not a problem");
     }
 
+    // ── validatePanePlacementAgainstLeadTabs ────────────────────────────────────────────────────
+
+    /**
+     * 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.
+     */
+    @Test
+    void aPanePlacedProfileWithALeadTabRefusesToStart(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("pane-hazard.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                profiles:
+                  gx10:
+                    placement: pane
+                fleet:
+                  leaders:
+                    opus:
+                      tab: "lead: opus"
+                """);
+        FleetConfig cfg = FleetConfig.load(f);
+
+        IllegalStateException e = assertThrows(IllegalStateException.class,
+                cfg::validatePanePlacementAgainstLeadTabs);
+        assertTrue(e.getMessage().contains("gx10"), "the message must name the offending profile");
+    }
+
+    @Test
+    void aPanePlacedProfileWithNoLeadTabIsAllowed(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("pane-no-tab.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                profiles:
+                  gx10:
+                    placement: pane
+                fleet:
+                  leaders:
+                    opus:
+                      profile: gx10
+                """);
+
+        assertDoesNotThrow(() -> FleetConfig.load(f).validatePanePlacementAgainstLeadTabs(),
+                "a leader with no tab feeds nothing into the scanner, so pane placement is safe");
+    }
+
+    @Test
+    void aTabPlacedProfileWithALeadTabIsAllowed(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("tab-safe.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                profiles:
+                  gx10:
+                    placement: tab
+                fleet:
+                  leaders:
+                    opus:
+                      tab: "lead: opus"
+                """);
+
+        assertDoesNotThrow(() -> FleetConfig.load(f).validatePanePlacementAgainstLeadTabs(),
+                "a member in its own tab cannot land inside a lead's tab");
+    }
+
+    /** Proves the reflective sweep behind {@code validateAll} really reaches this validator. */
+    @Test
+    void validateAllAlsoRefusesPanePlacementAgainstALeadTab(@TempDir Path dir) throws Exception {
+        Path f = dir.resolve("pane-hazard-sweep.yaml");
+        Files.writeString(f, """
+                bind:
+                  port: 8080
+                profiles:
+                  gx10:
+                    placement: pane
+                fleet:
+                  leaders:
+                    opus:
+                      tab: "lead: opus"
+                """);
+        FleetConfig cfg = FleetConfig.load(f);
+
+        IllegalStateException e = assertThrows(IllegalStateException.class, cfg::validateAll);
+        assertTrue(e.getMessage().contains("gx10"), "the message must name the offending profile");
+    }
+
     // ── CB-530/CB-579: the leaders registry ─────────────────────────────────────────────────────
 
     @Test

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

@@ -42,12 +42,13 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  *       has right now. This is the proof that a future, real seventh validator on {@link
  *       FleetConfig} would be swept automatically, without needing to add a real (unwanted)
  *       seventh validator just to exercise the claim.</li>
- *   <li>{@link #validateAllReachesEveryOneOfTodaysSixValidators()} proves {@link
+ *   <li>{@link #validateAllReachesEveryOneOfTodaysRealValidators()} proves {@link
  *       FleetConfig#validateAll()} itself is wired to that same generic mechanism and genuinely
- *       reaches each of today's six real validators — reusing the exact minimal failing
+ *       reaches seven of today's eight real validators — reusing the exact minimal failing
  *       configurations {@code FleetConfigTest} already established for each one directly, so a
- *       single call to {@code validateAll()} is shown to reproduce every one of those six
- *       failures.</li>
+ *       single call to {@code validateAll()} is shown to reproduce every one of those seven
+ *       failures. The eighth, {@link FleetConfig#validateLeadRollover()}, has no case here yet —
+ *       a pre-existing gap tracked as fleetd #668.</li>
  * </ol>
  *
  * <p>Together with the direct-{@code Fleetd.main}-invocation tests in {@code
@@ -62,8 +63,8 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
  * the generic sweep — claim 1 proves {@link FleetConfig#invokeAllValidators} is generic, and claim
  * 2 proves {@code validateAll()} reaches today's six, and a hardcoded list satisfies both. So the
  * reflective sweep is a convenience, not the guarantee. The guarantee is {@link
- * #fleetConfigDeclaresExactlyTheseSixValidatorsToday()}: it fails the moment a seventh validator
- * is declared, which forces whoever adds it to look at this file.
+ * #fleetConfigDeclaresExactlyTheseValidatorsToday()}: it fails the moment any validator is added
+ * or removed, which forces whoever changes the set to look at this file.
  */
 class FleetConfigValidateAllTest {
 
@@ -209,18 +210,19 @@ class FleetConfigValidateAllTest {
                         + "name) must all be skipped");
     }
 
-    // ── Claim 2: FleetConfig.validateAll() is wired to that mechanism and reaches all six today ──
+    // ── Claim 2: FleetConfig.validateAll() is wired to that mechanism and reaches seven of eight today ──
 
     /**
      * Reflectively enumerates {@link FleetConfig}'s own public, no-arg, void {@code validateXxx()}
      * methods (excluding {@code validateAll} itself) — the exact same filter {@link
      * FleetConfig#invokeAllValidators} applies. This is not the mechanism proof (that is claim 1,
-     * above, on an unrelated class) — it is a visible denominator: today there are six, named
-     * here, so a reader adding a seventh sees this assertion name the new count rather than a
-     * silent pass at the old one.
+     * above, on an unrelated class) — it is a visible denominator: today there are eight, named in
+     * the {@code Set.of} below, so a reader adding or removing one sees this assertion name the new
+     * count rather than a silent pass at the old one. The count lives only in that set, not in this
+     * method's name, so the two cannot drift apart.
      */
     @Test
-    void fleetConfigDeclaresExactlyTheseSixValidatorsToday() {
+    void fleetConfigDeclaresExactlyTheseValidatorsToday() {
         Set<String> names = new TreeSet<>();
         for (Method m : FleetConfig.class.getMethods()) {
             if (java.lang.reflect.Modifier.isPublic(m.getModifiers())
@@ -233,7 +235,8 @@ class FleetConfigValidateAllTest {
         }
         assertEquals(new TreeSet<>(Set.of("validateAuthExposure", "validateLeadTabPrefixes",
                 "validateSubscriptionProfiles", "validateCharters", "validateMembers",
-                "validateModels", "validateLeadRollover")), names,
+                "validateModels", "validateLeadRollover", "validatePanePlacementAgainstLeadTabs")),
+                names,
                 "FleetConfig's public validate*() methods changed. Do TWO things, in this "
                         + "order. First confirm validateAll() still delegates to "
                         + "invokeAllValidators(this) — a hardcoded list there passes every other "
@@ -262,14 +265,17 @@ class FleetConfigValidateAllTest {
     }
 
     /**
-     * The heart of claim 2: for each of today's six real validators, a minimal file that fails
+     * The heart of claim 2: for seven of today's eight real validators, a minimal file that fails
      * ONLY that one — the exact fixtures {@code FleetConfigTest} uses to test each validator
      * directly — must also fail through {@link FleetConfig#validateAll()}. If a future edit to
-     * {@code validateAll()} silently dropped one validator from the sweep (e.g. a typo'd name
-     * filter), exactly one of these six would start passing when it must not.
+     * {@code validateAll()} silently dropped one of these seven from the sweep (e.g. a typo'd name
+     * filter), exactly one of them would start passing when it must not.
+     *
+     * <p>The eighth, {@link FleetConfig#validateLeadRollover()}, has no case here — a pre-existing
+     * gap tracked as fleetd #668, not fixed by this change.
      */
     @Test
-    void validateAllReachesEveryOneOfTodaysSixValidators(@TempDir Path dir) throws Exception {
+    void validateAllReachesEveryOneOfTodaysRealValidators(@TempDir Path dir) throws Exception {
         // validateAuthExposure: a non-loopback bind without token mode.
         assertValidateAllRefuses(dir, "auth-exposure.yaml", """
                 bind:
@@ -342,6 +348,20 @@ class FleetConfigValidateAllTest {
                   allow:
                     - model: claude-sonnet-5
                 """, "rogue");
+
+        // validatePanePlacementAgainstLeadTabs: a pane-placed profile while a lead names a tab.
+        assertValidateAllRefuses(dir, "pane-placement.yaml", """
+                bind:
+                  host: 127.0.0.1
+                  port: 8765
+                profiles:
+                  gx10:
+                    placement: pane
+                fleet:
+                  leaders:
+                    opus:
+                      tab: "lead: opus"
+                """, "gx10");
     }
 
     private static void assertValidateAllRefuses(Path dir, String fileName, String yaml,

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

@@ -232,8 +232,9 @@ class LeadTabScannerTest {
 
     @Test
     void everyPaneInALeadTabResolvesAsThatLead() {
-        // A human may split their own lead tab. Both panes are theirs, so both are that lead —
-        // nothing fleetd placed can land here (see the worker-space test above).
+        // A human may split their own lead tab. Both panes are theirs, so both are that lead.
+        // A pane-placed member landing here instead is refused at startup by
+        // FleetConfig.validatePanePlacementAgainstLeadTabs, not by this scanner.
         TopologyHerdr herdr = twoLeads().pane("w1:p1b", "w1:t1", "term_opus_split");
 
         assertEquals("opus-5.0",