diff --git a/.engine/knowledge/graph.json b/.engine/knowledge/graph.json
index 144305e..abaf4a4 100644
--- a/.engine/knowledge/graph.json
+++ b/.engine/knowledge/graph.json
@@ -2684,7 +2684,7 @@
       },
       "slug": "boot-session-start",
       "source": {
-        "fingerprint": "sha256:e4bfb5d394d5472371e3d2220be624de8161e41af26580fd59fafe5d041ba983",
+        "fingerprint": "sha256:d90d6fc411f942130ab0026d167b6675bb55adcb0687213361d08b991ccee17e",
         "path": ".engine/operations/boot-session-start.md"
       },
       "status": "active",
@@ -4002,7 +4002,7 @@
       },
       "slug": "boot",
       "source": {
-        "fingerprint": "sha256:5a26c1c51f59caee6a2b484b6ffc973466cf9134ef62ba9da9bcceb87c0393cb",
+        "fingerprint": "sha256:c2cc6eea7825e50fc787057a8b92cde6a7ab3a8229ead24c0a3b2010abc7c0e0",
         "path": ".engine/tools/boot.py"
       },
       "status": "active",
@@ -5651,7 +5651,7 @@
       },
       "slug": "test_boot",
       "source": {
-        "fingerprint": "sha256:bee5261ab0ea9f5b5e9e37628b3aed09021d2ab03eb5dd2b0e3468b678794b18",
+        "fingerprint": "sha256:760e716a7ae967b9aebfb0fd8c31afb249f5c2d83de11ac81f0aba5483fe7dee",
         "path": ".engine/tools/test_boot.py"
       },
       "status": "active",
diff --git a/.engine/operations/boot-session-start.md b/.engine/operations/boot-session-start.md
index 2e4e8cc..27810e0 100644
--- a/.engine/operations/boot-session-start.md
+++ b/.engine/operations/boot-session-start.md
@@ -48,6 +48,10 @@ only, never the whole pack, and the session never halts.
      the terse-versus-full decision, and the write all run in the deterministic hook (`boot_alarm_ledger`),
      never the model, and are **fail-toward-full**: a missing/unreadable/write-failed ledger, or any
      ambiguity, renders the alarm in full (repetition is the tolerable failure; suppression is not).
+     The relay is a **once-per-session act in the grounding reply**: each alarm is named with its
+     consequence in plain words, never wrapped in an invented "boot check" / "before we start setup"
+     preamble, and the "(unchanged since last session)" framing is **not re-surfaced on later turns** of
+     the same session (if asked again, answer plainly without restapling the boot wrapper).
 
 To print the assembled briefing by hand (a debug view of what the hook injects): `python tools/boot.py pack`.
 
diff --git a/.engine/tools/boot.py b/.engine/tools/boot.py
index 80826f7..cb9c632 100644
--- a/.engine/tools/boot.py
+++ b/.engine/tools/boot.py
@@ -997,11 +997,17 @@ def assemble_pack(session_id: str | None = None, *, use_ledger: bool = False) ->
         # (unchanged since last session)" is a standing one already seen — relay it as the brief reminder
         # it is; a new or worsened item is stated in full. If a standing alarm has dropped off entirely
         # since last session, that means the engine re-checked and it is resolved — not that it stopped
-        # watching; say so plainly if the operator asks.
+        # watching; say so plainly if the operator asks. The emitted instruction below also bounds WHEN the
+        # relay happens — once, in this grounding reply, with no invented "boot check" preamble and not
+        # re-surfaced on later turns; keep this comment and that emitted text in step.
         out.append("   (An item marked 'still … (unchanged since last session)' is a standing one the "
                    "operator already saw — relay it as a brief reminder, not a fresh alarm; a new or "
                    "worsened item is stated in full. An alarm that dropped off since last session means "
-                   "the engine verified it resolved, never that it stopped checking.)")
+                   "the engine verified it resolved, never that it stopped checking. Relay each alarm "
+                   "once, here in this grounding reply, naming the thing and its consequence in plain "
+                   "words — do not invent a 'boot check' or 'before we start setup' preamble, and do not "
+                   "re-surface this framing on later turns of the same session. If the operator asks "
+                   "again, answer plainly, without the boot-time framing.)")
     else:
         out.append("2. No governance alarm to relay this session.")
     out.append("3. Then surface a brief plain-language headline of anything in the status below that needs "
diff --git a/.engine/tools/test_boot.py b/.engine/tools/test_boot.py
index 3cd0a5b..820f50b 100644
--- a/.engine/tools/test_boot.py
+++ b/.engine/tools/test_boot.py
@@ -1046,6 +1046,18 @@ def test_marker_token_in_briefing_on_the_alarm_branch(self):
         self.assertIn(boot.PRESENT_MARKER, pack)            # ...but the instruction still names it
         self.assertIn(boot.RELAY_MARKER, pack)              # ...and the governance alarm is INFORM-marked
 
+    def test_collapse_contract_bounds_the_relay_to_the_grounding_reply(self):
+        # The AI-facing collapse contract must not just say HOW to render a collapsed alarm — it must bound
+        # WHEN: a once-per-session act in this grounding reply, with no invented "boot check" preamble and no
+        # re-surfacing of the "(unchanged since last session)" framing on later turns. This is the guard
+        # against a model restapling the boot wrapper mid-session (the leak the operator caught).
+        with mock.patch.object(boot, "gather_signals",
+                               return_value=_signals(gate="off", reason="no pull request")):
+            pack = boot.assemble_pack()
+        self.assertIn("Relay each alarm once", pack)            # once-per-session bound
+        self.assertIn("do not invent a 'boot check'", pack)    # no invented preamble
+        self.assertIn("later turns of the same session", pack)  # no mid-session re-surfacing
+
     def test_must_push_carries_the_inform_marker_for_governance(self):
         items = boot.must_push(_signals(gate="off", reason="no pull request"))
         self.assertTrue(items)