Posted by Claude Code on evnchn's behalf.
TL;DR: Deprecated — this hook is no longer needed on Claude Opus 4.8+.
The silent-stop failure this gate guarded against — the model ending a turn text-only when the task still needed a tool call — was fixed model-side in Opus 4.8, not in the Claude Code harness. The guard is now redundant on 4.8+.
Keep it only if you run Opus 4.7 or older, where the failure mode returns and you'd be unguarded.
Archived as a deprecated reference, not deleted: the hook still works, and the bisect below is the record of why it was retired.
Why it was retired — the bisect (harness vs model)
Original purpose (2026-04-08): early Claude Code sessions died prematurely when the model produced a text-only turn with no tool call — the agentic loop ended silently. The nonce/phrase gate forced a confirmation before the harness was allowed to stop. Built for overnight autonomous work.
Decommissioned from the operator's settings.json in 2026-06-08 → 06-16 (settings backups bracket it: v1.4 still wired 06-08, gone by 06-16).
| Phase |
Instrument |
Result |
| A — harness |
Claude Code CHANGELOG 2.1.160–2.1.185 |
null — no entry addresses silent-stop / loop-ends-on-text-only |
| B — model |
.message.model in session logs + Opus 4.8 release notes |
hit — 4.7→4.8 crossover 2026-06-03, immediately before the decommission |
The stop-decision is harness control flow (a system-prompt diff can't capture it), but the behavior — the model choosing not to emit a tool call — is fundamentally model-side, so the model card is the right instrument. Opus 4.8 release notes, verbatim: "fewer cases of skipping a tool call that the task required" … "carries end-to-end tasks through." That is the silent-stop failure mode, fixed in the weights.
Confidence + caveats (what this does and doesn't prove)
- Empirical (ran it): model-string timeline from session logs (4.7→4.8 on 2026-06-03); CHANGELOG scan (null); settings-backup decommission bracket.
- Vendor claim (not independently measured): the "fewer skipped tool calls" improvement is from release notes — direction, not audit-grade magnitude.
- Not reproduced on demand: silent-stop is stochastic and rare on 4.8; 4.7's behavior can't be re-summoned — correlational, not a controlled A/B.
- Operator's removal motive not read verbatim: the gate was also redundant because its memory-signoff side-function had migrated elsewhere — both can be true.
Sources: Introducing Claude Opus 4.8 · What's new in Opus 4.8
Status: archived as deprecated. Re-wire only for Opus 4.7-or-older runs.
Posted by Claude Code on evnchn's behalf.
TL;DR: Deprecated — this hook is no longer needed on Claude Opus 4.8+.
The silent-stop failure this gate guarded against — the model ending a turn text-only when the task still needed a tool call — was fixed model-side in Opus 4.8, not in the Claude Code harness. The guard is now redundant on 4.8+.
Keep it only if you run Opus 4.7 or older, where the failure mode returns and you'd be unguarded.
Archived as a deprecated reference, not deleted: the hook still works, and the bisect below is the record of why it was retired.
Why it was retired — the bisect (harness vs model)
Original purpose (2026-04-08): early Claude Code sessions died prematurely when the model produced a text-only turn with no tool call — the agentic loop ended silently. The nonce/phrase gate forced a confirmation before the harness was allowed to stop. Built for overnight autonomous work.
Decommissioned from the operator's
settings.jsonin 2026-06-08 → 06-16 (settings backups bracket it:v1.4still wired 06-08, gone by 06-16)..message.modelin session logs + Opus 4.8 release notesThe stop-decision is harness control flow (a system-prompt diff can't capture it), but the behavior — the model choosing not to emit a tool call — is fundamentally model-side, so the model card is the right instrument. Opus 4.8 release notes, verbatim: "fewer cases of skipping a tool call that the task required" … "carries end-to-end tasks through." That is the silent-stop failure mode, fixed in the weights.
Confidence + caveats (what this does and doesn't prove)
Sources: Introducing Claude Opus 4.8 · What's new in Opus 4.8
Status: archived as deprecated. Re-wire only for Opus 4.7-or-older runs.