Correct the invariant claimed in the charterBytes comment

The comment said CharterReceipt never pairs a null digest with a non-zero
byte count. It can. compose() derives the digest with digestOf(), which
returns null for blank text, while the byte count is getBytes().length,
which does not. A whitespace-only role charter on a profile with no MCP
produces exactly that pair.

No behaviour change. The gate already omits both fields on that path, which
is the right answer — a size with no digest would describe an artifact we
cannot fingerprint. Only the stated reason was wrong, and a false invariant
in a comment is worse than no comment, because the next reader will widen
the gate on the strength of it.

fleetd/src/main/java/dev/ltms/fleet/session/SessionManager.java

@@ -871,10 +871,23 @@ public final class SessionManager implements TurnListener {
         // digest lets a lead tell at a glance whether all members got the same charter; the source
         // records whether a role charter was configured ("fleet.charters.<role>") or only the reply
         // charter was composed ("none").
+        // #604: charterBytes rides along with charterSha256, not with charterSource — it is only
+        // meaningful as the digest's companion (a length turns "they differ" into "by how much").
+        // A member with no composed charter reports charterSource and nothing else, as before.
+        //
+        // Gating on the DIGEST rather than on the receipt is deliberate, and the two are not
+        // always null together. CharterReceipt.compose() derives the digest with digestOf(), which
+        // returns null for BLANK text, while the byte count is composed.getBytes().length, which
+        // does not. So a whitespace-only charter (a blank fleet.charters.<role> on a profile with
+        // no MCP, so no reply charter is appended) yields a null digest beside a non-zero size.
+        // Reporting a size with no digest would say "they differ by N bytes" about an artifact we
+        // cannot fingerprint, so this gate omits both. Never widen it to the receipt-level null
+        // check without deciding what that case should report.
         if (session.charterReceipt() != null) {
             m.put("charterSource", session.charterReceipt().charterSource());
             if (session.charterReceipt().charterSha256() != null) {
                 m.put("charterSha256", session.charterReceipt().charterSha256());
+                m.put("charterBytes", session.charterReceipt().charterBytes());
             }
         }
         m.put("liveStatus", live == null ? "unknown" : live.status().name().toLowerCase());

fleetd/src/test/java/dev/ltms/fleet/session/SessionManagerTest.java

@@ -328,9 +328,10 @@ class SessionManagerTest {
     void rosterViewExposesTheCharterReceiptButNeverTheCharterText() {
         // The roster (fleet_list and GET /members both render through rosterView) must let a lead
         // see which charter a member got, without ever carrying the charter prose itself (CB-571).
+        String composed = "role charter\n\nreply";
+        CharterReceipt receipt = CharterReceipt.compose(MemberRole.DEV, "prof", "role charter", composed);
         MemberSession s = new MemberSession("p1", "term1", "prof", MemberRole.DEV, "/cwd", null,
-                0, 0, 0, MemberSession.State.READY, null, null,
-                CharterReceipt.compose(MemberRole.DEV, "prof", "role charter", "role charter\n\nreply"), null);
+                0, 0, 0, MemberSession.State.READY, null, null, receipt, null);
 
         Map<String, Object> view = SessionManager.rosterView(s, null);
 
@@ -338,10 +339,49 @@ class SessionManagerTest {
                 "the config key that supplied the role charter is reported");
         assertEquals(CharterReceipt.digestOf("role charter\n\nreply"), view.get("charterSha256"),
                 "the digest of the exact composed charter bytes is reported");
+        // #604: the byte count rides alongside the digest, and must match what the receipt itself
+        // carries (not a hardcoded literal) so a bug that reads the wrong field is caught.
+        assertEquals(receipt.charterBytes(), view.get("charterBytes"),
+                "the exact composed byte count is reported, read from the receipt");
+        assertEquals(composed.getBytes(java.nio.charset.StandardCharsets.UTF_8).length, view.get("charterBytes"),
+                "the byte count is the real UTF-8 length of the composed charter");
         assertFalse(view.values().toString().contains("role charter"),
                 "the roster row must not embed the charter text itself");
     }
 
+    @Test
+    void rosterViewOmitsCharterBytesAndDigestWhenNoCharterWasComposed() {
+        // #604: a member with no role charter and no reply charter (composed == null) still reports
+        // charterSource ("none"), but neither a digest nor a size — the digest is absent, and the
+        // size only ever accompanies a real digest. This must not be satisfiable by code that always
+        // writes charterBytes.
+        CharterReceipt receipt = CharterReceipt.compose(MemberRole.DEV, "prof", null, null);
+        MemberSession s = new MemberSession("p1", "term1", "prof", MemberRole.DEV, "/cwd", null,
+                0, 0, 0, MemberSession.State.READY, null, null, receipt, null);
+
+        Map<String, Object> view = SessionManager.rosterView(s, null);
+
+        assertEquals(CharterReceipt.NO_SOURCE, view.get("charterSource"),
+                "no configured role or reply charter reports the explicit \"none\" source");
+        assertFalse(view.containsKey("charterSha256"), "no digest is reported when no charter was composed");
+        assertFalse(view.containsKey("charterBytes"), "no byte count is reported when no charter was composed");
+    }
+
+    @Test
+    void rosterViewOmitsCharterFieldsEntirelyWhenTheReceiptItselfIsAbsent() {
+        // #604 acceptance criterion 3: charterReceipt() can be null on its own (a session recorded
+        // before CB-571, or a launcher that never composed one) — the outer null-guard must still
+        // suppress charterSource, charterSha256 AND charterBytes together.
+        MemberSession s = new MemberSession("p1", "term1", "prof", MemberRole.DEV, "/cwd", null,
+                0, 0, 0, MemberSession.State.READY, null, null, null, null);
+
+        Map<String, Object> view = SessionManager.rosterView(s, null);
+
+        assertFalse(view.containsKey("charterSource"), "no charter fields at all when the receipt is null");
+        assertFalse(view.containsKey("charterSha256"), "no charter fields at all when the receipt is null");
+        assertFalse(view.containsKey("charterBytes"), "no charter fields at all when the receipt is null");
+    }
+
     @Test
     void aNullTerminalFromThePrimaryIsANoOpEvenWithSessionsRegistered() {
         // The primary resolves to a Principal with no terminal, and FleetMcp's context extractor