diff --git a/cargento/skills/cargento/cargento_runtime/aggregate.py b/cargento/skills/cargento/cargento_runtime/aggregate.py
index 6c3e3034..dfcb4fa1 100644
--- a/cargento/skills/cargento/cargento_runtime/aggregate.py
+++ b/cargento/skills/cargento/cargento_runtime/aggregate.py
@@ -1253,6 +1253,7 @@ def _attach_command_reports(self, out_sessions: list[Session]) -> dict[str, Any]
                     if (report["harness"], report["sid"]) == (session["harness"], session["sid"])
                 ]
         return {
+            "ends_observable": self.overlays is not None,
             "irreversible_enabled": enabled,
             **({"command_reports": reports} if enabled else {}),
         }
diff --git a/cargento/skills/cargento/cargento_runtime/dismissals.py b/cargento/skills/cargento/cargento_runtime/dismissals.py
index d67d701e..876a0d43 100644
--- a/cargento/skills/cargento/cargento_runtime/dismissals.py
+++ b/cargento/skills/cargento/cargento_runtime/dismissals.py
@@ -66,6 +66,20 @@ def store_path(config: RuntimeConfig) -> str:
     return os.path.join(config.state_home, "cargento-dismissals.json")
 
 
+def is_matchable(harness: str, sid: str) -> bool:
+    """Whether (harness, sid) can ever match a published session row.
+
+    Claude Code sessions publish the 8-character transcript prefix as their
+    sid, so a 36-character UUID or other non-8-character identifier can never
+    match any published Claude row. Admitting an unmatchable key would write a
+    permanent junk entry that never expires on activity, consuming one of the
+    bounded dismissal slots and eventually evicting a real dismissal (DRC-4179).
+    """
+    if not harness or not sid:
+        return False
+    return not (harness == "claude" and len(sid) > 8)
+
+
 def _entry(value: Any) -> Dismissal | None:
     """One untrusted record as a dismissal, or nothing.
 
@@ -79,7 +93,7 @@ def _entry(value: Any) -> Dismissal | None:
         return None
     harness = records.safe_text(value.get("harness"), KEY_CAP_CHARS).strip()
     sid = records.safe_text(value.get("sid"), KEY_CAP_CHARS).strip()
-    if not harness or not sid:
+    if not is_matchable(harness, sid):
         return None
     return {
         "harness": harness,
@@ -258,7 +272,7 @@ def dismiss(
     if not config.dismissals_enabled:
         return False
     key = _key(harness, sid)
-    if not key[0] or not key[1]:
+    if not is_matchable(key[0], key[1]):
         return False
     stamp = time.time() if now is None else now
     entry: Dismissal = {
@@ -290,6 +304,8 @@ def restore(
     if not config.dismissals_enabled:
         return False
     key = _key(harness, sid)
+    if not is_matchable(key[0], key[1]):
+        return False
     with state.dismissal_lock:
         bounded = tuple(e for e in load(config) if (e["harness"], e["sid"]) != key)
         state.dismissals = _stored(bounded)
diff --git a/cargento/skills/cargento/cargento_runtime/http_api.py b/cargento/skills/cargento/cargento_runtime/http_api.py
index d4d6d8f1..15869c9d 100644
--- a/cargento/skills/cargento/cargento_runtime/http_api.py
+++ b/cargento/skills/cargento/cargento_runtime/http_api.py
@@ -1201,7 +1201,6 @@ def _dismiss(self) -> None:
         answer = {
             "ok": True,
             "persisted": persisted,
-            "cleared": len(dismissals.active(config, state)),
         }
         self._send(json.dumps(answer, separators=(",", ":")).encode(), "application/json")
 
diff --git a/cargento/skills/cargento/cargento_runtime/web/next-observed.js b/cargento/skills/cargento/cargento_runtime/web/next-observed.js
index 790b273d..20e2c853 100644
--- a/cargento/skills/cargento/cargento_runtime/web/next-observed.js
+++ b/cargento/skills/cargento/cargento_runtime/web/next-observed.js
@@ -472,7 +472,7 @@ function nextObserved(payload, evidence){
     quiet: `The other ${other.length}: ${otherWords.filter(word => word[1]).map(word => `${word[1]} ${word[0]}`).join(" · ") || "none"}; ` +
       `of these, ${partial} partially read.`,
     gates: `${totals.reportsBlock} of ${totals.sessions} ${totals.sessions === 1 ? "session reports" : "sessions report"} block state · ` +
-      `${totals.sessions - totals.reportsBlock} unknown · ends observed on ${totals.ended} ${totals.ended === 1 ? "session" : "sessions"}`,
+      `${totals.sessions - totals.reportsBlock} unknown · ${payload.ends_observable === false ? "ends unobservable" : `ends observed on ${totals.ended} ${totals.ended === 1 ? "session" : "sessions"}`}`,
     rows: harnesses.map(row => ({key: String(row.key || ""), label: nextObservedString(row.label) || String(row.key || "Harness not published"),
       sessions: sessions.filter(session => session.harness === row.key).length,
       ...nextObservedPair("block", !row.error && row.reports_needs_input === true ?
diff --git a/cargento/skills/cargento/cargento_runtime/web/next-session.js b/cargento/skills/cargento/cargento_runtime/web/next-session.js
index 056a4954..6effc6a1 100644
--- a/cargento/skills/cargento/cargento_runtime/web/next-session.js
+++ b/cargento/skills/cargento/cargento_runtime/web/next-session.js
@@ -112,24 +112,26 @@ function nextSessionMeta(session){
   const parts = [];
   const harness = nextSessionRegistryLabel(session);
   if(harness) parts.push(harness);
-  if(session.state_detail) parts.push(String(session.state_detail));
-  /* Outside the state chain below, on purpose. An end is a fact about the
-     session id; `state` is a reading of file recency that a session which ended
-     seconds ago can still make say "working". */
+  /* An observed end supersedes the present-tense activity and duration phrases;
+     an ended session must not describe itself as awaiting input (DRC-4554). */
   const ended = nextDurationSince(nextSessionEndedAt(session));
-  if(ended != null) parts.push(`ended ${ended} ago`);
-  if(session.state === "needs_input"){
-    const blocked = nextDurationSince(session.blocked_since);
-    if(blocked != null) parts.push(`blocked ${blocked}`);
-    if(session.wait_unconfirmed) parts.push("unconfirmed: no positive observation in 5m");
-  }else if(session.state === "working"){
-    const turn = session.turn;
-    const elapsed = turn && typeof turn === "object" && !Array.isArray(turn) &&
-      typeof turn.elapsed_h === "string" ? turn.elapsed_h.trim() : "";
-    if(elapsed) parts.push(`turn started ${elapsed} ago`);
-  }else if(session.state === "idle"){
-    const started = nextDurationSince(session.started_at);
-    if(started != null) parts.push(`session started ${started} ago`);
+  if(ended != null){
+    parts.push(`ended ${ended} ago`);
+  }else{
+    if(session.state_detail) parts.push(String(session.state_detail));
+    if(session.state === "needs_input"){
+      const blocked = nextDurationSince(session.blocked_since);
+      if(blocked != null) parts.push(`blocked ${blocked}`);
+      if(session.wait_unconfirmed) parts.push("unconfirmed: no positive observation in 5m");
+    }else if(session.state === "working"){
+      const turn = session.turn;
+      const elapsed = turn && typeof turn === "object" && !Array.isArray(turn) &&
+        typeof turn.elapsed_h === "string" ? turn.elapsed_h.trim() : "";
+      if(elapsed) parts.push(`turn started ${elapsed} ago`);
+    }else if(session.state === "idle"){
+      const started = nextDurationSince(session.started_at);
+      if(started != null) parts.push(`session started ${started} ago`);
+    }
   }
   /* These last two are unconditional, and both for the reason the first one
      gives: every clause above is a reading, and these say what the readings
diff --git a/cargento/skills/cargento/tests/test_dismissals.py b/cargento/skills/cargento/tests/test_dismissals.py
index 890704b5..2f64da0c 100644
--- a/cargento/skills/cargento/tests/test_dismissals.py
+++ b/cargento/skills/cargento/tests/test_dismissals.py
@@ -362,5 +362,39 @@ def test_the_defaults_are_bounded(self) -> None:
         self.assertIs(True, dataclasses.replace(config, dismissals_enabled=True).dismissals_enabled)
 
 
+class MatchableKeyTest(DismissalStoreTestCase):
+    """DRC-4179: an unmatchable key cannot consume a slot or evict a real dismissal."""
+
+    def test_an_unmatchable_claude_uuid_is_refused(self) -> None:
+        config, state = self.runtime()
+        # Full 36-char UUID for Claude: can never match an 8-character prefix row.
+        uuid_sid = "12345678-1234-1234-1234-123456789abc"
+        persisted = dismissals.dismiss(config, state, "claude", uuid_sid, now=1000.0)
+        self.assertFalse(persisted)
+        self.assertEqual((), dismissals.load(config))
+
+    def test_an_unmatchable_entry_in_store_is_dropped_on_load(self) -> None:
+        config, _state = self.runtime()
+        self.write_store(
+            {
+                "v": 1,
+                "entries": [
+                    # Real 8-char Claude sid
+                    {"harness": "claude", "sid": "abcd1234", "at": 100.0, "seen_activity": 100.0},
+                    # Junk 36-char UUID sid that can never match
+                    {
+                        "harness": "claude",
+                        "sid": "12345678-1234-1234-1234-123456789abc",
+                        "at": 200.0,
+                        "seen_activity": 200.0,
+                    },
+                ],
+            }
+        )
+        loaded = dismissals.load(config)
+        self.assertEqual(1, len(loaded))
+        self.assertEqual("abcd1234", loaded[0]["sid"])
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/cargento/skills/cargento/tests/test_focus.py b/cargento/skills/cargento/tests/test_focus.py
index 41b252d0..c3f18b6a 100644
--- a/cargento/skills/cargento/tests/test_focus.py
+++ b/cargento/skills/cargento/tests/test_focus.py
@@ -1021,7 +1021,7 @@ def test_the_pinned_assembly_is_untouched(self) -> None:
         # would fail on the reader rather than on an injected token.
         self.assertNotIn(b'<meta name="cargento-focus"', assembled)
         self.assertEqual(
-            "f7cd56b1aa750b7b8980d4e20e1e55792fba13d995de22497bd732eb5c9afa63",
+            "7c0dbcb341cd1652e60821fde01b3c1080bc58022100bfa9ba25317fefb1c52a",
             hashlib.sha256(assembled).hexdigest(),
         )
 
diff --git a/cargento/skills/cargento/tests/test_http_api.py b/cargento/skills/cargento/tests/test_http_api.py
index 71b3124d..aa8e2124 100644
--- a/cargento/skills/cargento/tests/test_http_api.py
+++ b/cargento/skills/cargento/tests/test_http_api.py
@@ -633,7 +633,7 @@ def test_a_mark_reaches_the_store_and_the_next_read_reflects_it(self) -> None:
         self.assertEqual((200, 200, 200), (first, status, listed_status))
         answer = json.loads(body)
         self.assertIs(True, answer["persisted"])
-        self.assertEqual(1, answer["cleared"])
+        self.assertNotIn("cleared", answer)
         self.assertEqual(
             [{"harness": "claude", "sid": "abcd1234"}],
             [{k: v for k, v in row.items() if k != "at"} for row in json.loads(listed)["cleared"]],
@@ -656,7 +656,27 @@ def test_a_body_that_names_nothing_is_a_no_op(self) -> None:
                 with self.subTest(body=body):
                     status, answer = self._post(port, body)
                     self.assertEqual(200, status)
-                    self.assertEqual(0, json.loads(answer)["cleared"])
+                    self.assertNotIn("cleared", json.loads(answer))
+
+    def test_an_unmatchable_key_returns_persisted_false_and_does_not_persist(self) -> None:
+        config, state = self._runtime()
+        with self._serving(cli.build_application(config, state, clock=time.time)) as port:
+            status, body = self._post(
+                port,
+                json.dumps(
+                    {
+                        "harness": "claude",
+                        "sid": "12345678-1234-1234-1234-123456789abc",
+                    }
+                ).encode(),
+            )
+            listed_status, listed = self._get(port, "/api/cleared")
+        self.assertEqual(200, status)
+        self.assertEqual(200, listed_status)
+        answer = json.loads(body)
+        self.assertIs(False, answer["persisted"])
+        self.assertNotIn("cleared", answer)
+        self.assertEqual([], json.loads(listed)["cleared"])
 
     def test_the_rollback_switch_answers_503_on_both_routes(self) -> None:
         # 503, not 404: under `--no-dismiss` the route exists and the store does
diff --git a/cargento/skills/cargento/tests/test_next_attention.py b/cargento/skills/cargento/tests/test_next_attention.py
index 9093526c..3082b153 100644
--- a/cargento/skills/cargento/tests/test_next_attention.py
+++ b/cargento/skills/cargento/tests/test_next_attention.py
@@ -2261,8 +2261,8 @@ def model(self, sessions: list[dict[str, Any]]) -> Any:
             )
         )
 
-    def render(self, sessions: list[dict[str, Any]]) -> str:
-        payload = {"generated": 10_000, "sessions": sessions}
+    def render(self, sessions: list[dict[str, Any]], **extra: Any) -> str:
+        payload = {"generated": 10_000, "sessions": sessions, **extra}
         rendered = self._run_page_js(
             "\n".join(
                 (
@@ -2410,6 +2410,14 @@ def test_the_visible_coverage_line_counts_no_end_as_none_not_undefined(self) ->
         self.assertIn("ends observed on 0 sessions", visible)
         self.assertNotIn("undefined", visible)
 
+    def test_the_visible_coverage_line_says_unobservable_under_no_events(self) -> None:
+        # DRC-4555: under --no-events ends are unobservable, not zero observed.
+        html = self.render([self.row(sid="quiet-1")], ends_observable=False)
+        visible = html.split('<details class="next-attention-coverage-details"')[0]
+
+        self.assertIn("ends unobservable", visible)
+        self.assertNotIn("ends observed on 0 sessions", visible)
+
 
 @unittest.skipUnless(shutil.which("node"), "node not available")
 class HealthyBoardBriefTest(NextPageJsHarness):
diff --git a/cargento/skills/cargento/tests/test_next_flag.py b/cargento/skills/cargento/tests/test_next_flag.py
index 8e39c8c6..0430e7c4 100644
--- a/cargento/skills/cargento/tests/test_next_flag.py
+++ b/cargento/skills/cargento/tests/test_next_flag.py
@@ -64,9 +64,9 @@ def test_retired_next_query_is_not_a_page_alias(self) -> None:
     def test_the_canonical_loader_is_the_released_ui_bundle(self) -> None:
         page = frontend_page.load_page()
 
-        self.assertEqual(911_238, len(page))
+        self.assertEqual(911_302, len(page))
         self.assertEqual(
-            "f7cd56b1aa750b7b8980d4e20e1e55792fba13d995de22497bd732eb5c9afa63",
+            "7c0dbcb341cd1652e60821fde01b3c1080bc58022100bfa9ba25317fefb1c52a",
             hashlib.sha256(page).hexdigest(),
         )
 
diff --git a/cargento/skills/cargento/tests/test_next_observed.py b/cargento/skills/cargento/tests/test_next_observed.py
index 7ddf2a16..a43b13ac 100644
--- a/cargento/skills/cargento/tests/test_next_observed.py
+++ b/cargento/skills/cargento/tests/test_next_observed.py
@@ -152,6 +152,20 @@ def test_every_denominator_comes_from_the_same_thirteen_sessions(self) -> None:
         self.assertEqual(["alpha", "epsilon", "beta"], out["activeProjects"])
         self.assertEqual(["zeta", "delta", "gamma", "theta"], out["rest"])
 
+    def test_gates_coverage_distinguishes_unobservable_ends_from_none_observed(self) -> None:
+        # DRC-4555: under --no-events ends are unobservable, not zero observed.
+        out = self._run_page_js(
+            self.FIXTURE
+            + """
+payload.ends_observable = false;
+console.log(JSON.stringify(nextObserved(payload).coverage.gates));
+"""
+        )
+        self.assertEqual(
+            "9 of 13 sessions report block state · 4 unknown · ends unobservable",
+            out,
+        )
+
     def test_every_text_has_a_nonempty_value_and_known_boolean(self) -> None:
         out = self._run_page_js(
             self.FIXTURE
diff --git a/cargento/skills/cargento/tests/test_next_page.py b/cargento/skills/cargento/tests/test_next_page.py
index 03e57649..6ea2d483 100644
--- a/cargento/skills/cargento/tests/test_next_page.py
+++ b/cargento/skills/cargento/tests/test_next_page.py
@@ -616,8 +616,8 @@ def test_load_page_preserves_its_byte_oracles(self) -> None:
                 "b71d627fe8cc06bc4210d23c76c0ee5b2ab644ce15a44c9d617ba66fe398847d",
             ),
             "next-observed.js": (
-                31_136,
-                "931161c99c97d8f72fd30e7c9b104546541979b82eb7c8dec17bb4682d32edf2",
+                31_199,
+                "05d0574cd61663223ee75e8bb9eed8d10729733b737d79a4fa8943793116cb89",
             ),
             "next-attention.js": (
                 56_558,
@@ -664,8 +664,8 @@ def test_load_page_preserves_its_byte_oracles(self) -> None:
                 "62f971c5e2a570068b7e2c3ee72b2499774d14a3b739f6f908962f91b98382f1",
             ),
             "next-session.js": (
-                36_503,
-                "08099b828eb65c1c6c07f214a6e90c1cf18547249f5174e3aaf4379fb77d7bd1",
+                36_504,
+                "4a338ab2c9ce6ae7c197e1361df807a54bbf17b05078541cdba26eeef9fc1c9c",
             ),
             "next-workstream.js": (
                 18_659,
@@ -707,9 +707,9 @@ def test_load_page_preserves_its_byte_oracles(self) -> None:
         )
 
         assembled = frontend_page.load_page()
-        self.assertEqual(911_238, len(assembled))
+        self.assertEqual(911_302, len(assembled))
         self.assertEqual(
-            "f7cd56b1aa750b7b8980d4e20e1e55792fba13d995de22497bd732eb5c9afa63",
+            "7c0dbcb341cd1652e60821fde01b3c1080bc58022100bfa9ba25317fefb1c52a",
             hashlib.sha256(assembled).hexdigest(),
         )
 
diff --git a/cargento/skills/cargento/tests/test_next_session.py b/cargento/skills/cargento/tests/test_next_session.py
index 0d62b3c8..04e01bb6 100644
--- a/cargento/skills/cargento/tests/test_next_session.py
+++ b/cargento/skills/cargento/tests/test_next_session.py
@@ -1343,3 +1343,18 @@ def test_a_session_with_no_observed_end_still_reads_idle(self) -> None:
 
         self.assertNotIn("session ended", html)
         self.assertIn("idle", html)
+
+    def test_an_ended_session_does_not_describe_itself_as_awaiting_your_message(self) -> None:
+        # DRC-4554: header yields present-tense state phrase to an observed end.
+        html = self.detail(
+            'state_detail: "awaiting your message", finished_at: 9350, ended_at: 9400,'
+        )
+
+        self.assertIn("ended 10m ago", html)
+        self.assertNotIn("awaiting your message", html)
+
+    def test_a_non_ended_session_describes_itself_as_awaiting_your_message(self) -> None:
+        html = self.detail('state_detail: "awaiting your message", finished_at: 9350,')
+
+        self.assertIn("awaiting your message", html)
+        self.assertNotIn("ended 10m ago", html)