Flag absence and capability claims as unverified-shaped in diu-stop

engine/hooks/diu-stop/claude_stop_check.py

@@ -136,6 +136,12 @@
     re.IGNORECASE | re.DOTALL,
 )
 
+ABSENCE_CLAIM_RE = re.compile(
+    r"\b(?:has|have|had) no\b|\bthere (?:is|are|was|were) no\b|\bno single\b"
+    r"|\bno such (?:call|api|endpoint|function|way)\b|\b(?:can't|cannot|can not) be done\b",
+    re.IGNORECASE,
+)
+
 SENTENCE_END_RE = re.compile(r"(?<=[.!?])\s+")
 SENTENCE_LIMIT = 120
 
@@ -208,7 +214,7 @@ def _paragraph_claim(para):
     opener = _opening_word(para)
     if opener in BANNED_OPENERS:
         return opener, 0
-    for pattern in (CAUSAL_CLOSER_RE, HEDGE_CLAIM_RE):
+    for pattern in (CAUSAL_CLOSER_RE, HEDGE_CLAIM_RE, ABSENCE_CLAIM_RE):
         match = pattern.search(para)
         if match:
             return match.group(0), match.start()

engine/hooks/diu-stop/tests/fixtures/claims_fires.json

@@ -73,5 +73,30 @@
     "label": "which is why, the message's only fence holds a command, not output",
     "reply": "Both commands are in, and tools are **still** blocked. I also can't read the hook to diagnose it — the hook blocks that read too.\n\n**Run this and paste the output:**\n\n```\n! cat ~/.claude/hooks/scope-lock/claude_pretool_scope.py\n```\n\nThat shows me what actually clears the lock. Right now I'm guessing, and guessing is what got us here.\n\nWorth noting for the findings: a gate that blocks the read of its own source can't be diagnosed from inside the session it's gating — same shape as the `disable-model-invocation` rule already in your corpus, which is why that rule says the fix must live outside the thing it protects.",
     "hit": "which is why"
+  },
+  {
+    "label": "absence claim, has no",
+    "reply": "GitLab has no call that returns a merge request's whole job graph, so the client has to stitch it together.",
+    "hit": "has no"
+  },
+  {
+    "label": "absence claim, there is no",
+    "reply": "There is no way to read pipeline stages in one request from the public API.",
+    "hit": "there is no"
+  },
+  {
+    "label": "absence claim, no single",
+    "reply": "I found no single endpoint that lists every job with its needs.",
+    "hit": "no single"
+  },
+  {
+    "label": "absence claim, no such call",
+    "reply": "The SDK exposes no such call for listing job dependencies.",
+    "hit": "no such call"
+  },
+  {
+    "label": "capability claim, can't be done",
+    "reply": "Merging the two requests can't be done without changing the schema.",
+    "hit": "can't be done"
   }
 ]

engine/hooks/diu-stop/tests/fixtures/claims_silent.json

@@ -6,5 +6,17 @@
   {
     "label": "because with a backticked assignment, the message carries a fenced block of output",
     "reply": "**Correcting myself — it's alive.** The harness reported the wrapper exiting, not the job:\n\n```\n$ pgrep -af replay_causality\n292765 uv run python scripts/replay_causality.py\n292775 .venv/bin/python3 scripts/replay_causality.py\n\n$ tail -2 /tmp/replay.log\nreplaying 400,156 bars, full recompute at each\n  2,000/400,156 bars, 0 mismatches\n```\n\n**2,000 of 400,156 done, 0 mismatches.** Log looks stalled only because `PROGRESS_EVERY = 2000`."
+  },
+  {
+    "label": "absence claim next to fenced output",
+    "reply": "The schema has no `needs` field:\n\n```\n$ grep -c needs schema.graphql\n0\n```"
+  },
+  {
+    "label": "absence claim carrying a well-formed tag",
+    "reply": "{{CAT-UNVERIFIED: GitLab has no single call for the job graph -- cannot verify: the GraphQL docs page timed out twice}}"
+  },
+  {
+    "label": "plain reply with no absence phrase",
+    "reply": "Ed said the box is fine and the run is done."
   }
 ]