Imported from anthony-chaudhary/dos-kernel (src/dos/skills/dos-goal-gate/SKILL.md). Install upstream with npx skills add anthony-chaudhary/dos-kernel --skill dos-goal-gate. Copyright stays with the author.

dos-goal-gate — gate "I'm done" on a witness, not on self-report

A completion condition the agent checks against its own narration is the exact failure DOS exists to fix. When an agent decides "the goal is met" by re-reading what it just wrote, the part deciding ground truth is the part being judged — that is consistency, not grounding (docs/138). This skill never decides done-ness by re-reading the transcript. It turns the goal into a set of checkable EFFECT claims, then wires the Stop decision so the agent cannot stop until a read-back whose byte-author is not the agent (git ancestry, an OS exit code, a fresh state read) corroborates each effect. The kernel decides; the skill narrates.

The shape is domain-free: state the goal as effects → wire the Stop gate → on each stop, witness every effect → stop only when all are corroborated. The policy (which plan grammar, which lanes, where state lives) is data read from dos doctor --json, never literals this screenplay hardcodes.

Why this is not just "ask the model if it's done." A harness stop-condition ("keep going until X") is evaluated by a model reading the session — so a confident, fluent narration of an X that the world does not corroborate ends the work early (the silent fail of docs/177). The gate below replaces that judgment with a verdict over evidence the agent did not write: a phase is done when git says a commit backs it, not when the agent says it committed; a file exists when a fresh read finds it, not when the agent says it wrote it.

When to use this (and when not)

• Use it when a single agent self-paces toward a stated goal and you want its "done" to be unfalsifiable-by-narration — a /loop worker, a self-stopping task agent, or any run where the operator stated a completion condition.
• Use dos-witness-claim instead when many workers' results are folded at a parallel()/pipeline() barrier — that skill is the fan-out fold analogue; this one is the single-agent self-stop analogue. Same witness discipline, different site.
• This is advisory (a PDP, not a PEP — docs/99). It computes a Stop verdict and lets the runtime act on it via the user-owned hook seam. It blocks a false done; it never blocks a true one, and it never enforces beyond the Stop hook.

Inputs

• The operator's goal — the completion condition in plain words ("the auth refactor is shipped and the suite is green", "the migration plan's phases are all landed"). Free prose is the input, never the test.
• Optionally, a transcript path for the running session (the Stop event carries it; you rarely pass it by hand).

Step 0 — Discover the workspace layout (one call)

Run the doctor verb and read the result. Every path / lane / exit-code below comes from here, never a literal.

dos doctor --workspace . --json

The fields this skill uses:

• exit_codes.verify — {shipped, not_shipped, contract_error}. Branch on these for a git-phase effect (Step 2a), never on parsing prose.
• exit_codes."verify-result" — {healthy, unreadable, dead, contract_error} (dead=3). Branch on these for the terminal-state witness when a transcript is in play.
• paths.plans_glob / lanes / stamp — the host's plan grammar, lane taxonomy, and ship-stamp convention, if a goal names a (plan, phase).
• git — if false, the git-existence witness (Step 2a) has no history; every git-phase effect resolves source="none". Say so; do not silently pass it.
• runtime_hooks — which runtimes already have a dos hook … Stop entry wired (so you know whether Step 1 still needs doing).

Step 1 — Wire the Stop gate (once per workspace)

The gate is dos hook stop: a Stop / SubagentStop hook that refuses to let the agent stop while a confidently-CLAIMED phase is NOT corroborated by git. Wire it into the runtime's settings — idempotent, merged into any existing hooks, never clobbering the operator's own:

dos init --with-hooks --workspace .      # Claude Code (the default runtime)
# cross-runtime: dos init --hooks <runtime> --workspace .   (preview with --dry-run)

This binds three hooks; the load-bearing one here is Stop → dos hook stop. On every stop it extracts the (plan, phase) the agent claimed and refuses the stop (feeding the verdict back as the next instruction) if git does not back it. That refusal IS the grounded form of "keep working until the goal is met": the work cannot end on the agent's word that a phase shipped.

Two Stop hooks, opposite triggers — do not conflate them. dos hook stop blocks a false done (the agent claimed a phase, git disagrees). dos hook marker (docs/259) blocks a premature give-up while a keep-alive budget is unspent, then gets out of the way. A host may wire both; this skill is about the first. If your goal is "don't stop polling yet," that is dos hook marker, not this gate.

Step 1a — How this composes with the harness /goal command

The Claude Code /goal <condition> command is itself a session-scoped Stop hook — but a model-evaluated one: a fast model re-reads the session after each turn and rules on whether the condition holds. That is precisely the consistency-not-grounding shape this skill exists to fix — the judge is a model reading the agent's own narration, with no witness the agent did not author.

You do not replace /goal; you wire dos hook stop (Step 1) alongside it, and the harness combines them for you. Claude Code runs every matching Stop hook in parallel and applies an ANY-block rule: the stop is refused if any hook blocks it (a {"decision":"block",…} at exit 0, or exit 2). So with both active, the agent may stop only when the /goal model-judge AND the grounded git gate both allow it — a logical AND of "the narration reads done" and "ground truth backs it." The grounded gate can only ever add a refusal the model-judge missed; it never loosens /goal. That is the whole win: keep using /goal for its fluent, free, prose-level check, and let dos hook stop veto the case where the prose says done but git does not corroborate it.

The two hooks are independent — the gate does not read the goal text. A settings.json Stop hook receives the session/transcript, not the /goal condition string (the harness exposes no goal field to hooks). So dos hook stop does not "check the goal"; it independently checks that every phase the agent claimed shipped is backed by git. The alignment between the two is the operator's job: state the goal as the same checkable effects the gate verifies (Step 2), so "the model thinks it's done" and "git backs every claimed phase" converge on the same finish line. Do not write the gate as if it parses the goal — it parses the agent's claims and asks git.

Step 1b — The Fable-5 guide's "check your last paragraph" is the advisory form of this gate

Anthropic's Claude Fable 5 prompting guide has a section, "Rare cases of early stopping," for a known failure: deep in a long session the model can end a turn on a text-only statement of intent ("I'll now run X") without the tool call, or pause to ask permission it already has. Its fix is a prompt:

Before ending your turn, check your last paragraph. If it is a plan, an analysis, a question, a list of next steps, or a promise about work you have not done ("I'll…", "let me know when…"), do that work now with tool calls. End your turn only when the task is complete or you are blocked on input only the user can provide.

That is the advisory version of this skill, and dos hook stop is the enforced version that subsumes it. Same failure, opposite ends: the guide asks the model to re-read its OWN last paragraph (consistency, not grounding — the same shape Step 1a flags for /goal); the gate refuses the stop until a witness the agent did not author backs the claimed effect. The prompt lowers the frequency of "I'll now run X" early stops; the gate makes them impossible to get away with.

So a kernel reader migrating to Fable does not need to add the guide's prompt as a separate safeguard — the witness gate already covers that case. It is still fine to keep the prompt as defense-in-depth: it cuts the early stop before it happens, the gate catches the one that slips through. (An "I'll now run X" turn with no tool call and no shipped effect is exactly the unwitnessed-claim case the gate refuses — the operator sees a structured "your goal isn't witnessed yet, keep going," not a generic block.)

Step 2 — State the goal as checkable effects (the decomposition)

A goal is met when its effects are present in the world. Translate the prose goal into a list of named, checkable effects — and abstain rather than invent. An effect you cannot name an identifier for is not a passable goal; it is a NO_CLAIM to surface for the operator, never a test you fabricate (docs/134).

Map each effect to its witness rung:

The first two are shipped CLI verbs. The third is the open seam — handled honestly in Step 2b. The goal's "done" is the conjunction of all its effects' witnesses: every one CONFIRMED/SHIPPED, or the goal is not met.

Step 2a — git-phase effects: ask the truth syscall

For each (plan, phase) the goal names, never trust "I committed it" and never grep commit subjects yourself:

dos verify --workspace . <PLAN> <PHASE> --json
echo "exit=$?"

Read the ShipVerdict {shipped, source, sha?}, branch on exit_codes.verify, and read the rung:

• source: "registry" — the strongest git ship; a ship row exists. Effect met.
• source: "grep-subject" — a commit subject carried the phase token. SHIPPED, but weaker (a subject can flip the verdict even if little was built). Met, but mark the rung; do not treat it as equal to registry.
• source: "none" — no positive git evidence. The agent CLAIMED the phase but git does not corroborate it. The effect is NOT met — this is the narrated success the world does not back. The goal is unmet; keep working.

This is grounding because git is a witness the agent did not author: a commit's existence in ancestry is a fact about the repository, not about the agent's prose.

Step 2b — created-file / DB-row / sent-message effects: the read-back gap

There is NO dos verify-effect (or dos witness) CLI verb. The effect-witness join is shipped in the kernel as a Python API, not a command (exactly as tool_stream has no dos tool-stream verb — see EXAMPLES.md Recipe 5). So for any effect outside git, document the pattern and log the gap at runtime, rather than pretending a verb exists:

from dos.claim_extract import extract_claims          # (a) abstain, never invent
from dos.effect_witness import EffectClaim, witness_effect
from dos.evidence import gather_evidence, resolve_evidence_source  # (b) read-back

# (a) Extract the claim from the agent's terminal text. extract_claims fires only
#     on an explicit ID-shaped token or a DOS-CLAIM: marker — free prose yields [].
#     That [] is a NO_CLAIM (surface it), not a met effect.

# (b) Gather a read-back from a witness the agent did not author. A real witness
#     (a fresh HTTP GET, an OS exit code, a state-snapshot diff) lives in a driver
#     registered under the `dos.evidence_sources` entry-point group; resolve it by
#     name and run it at the boundary:
source = resolve_evidence_source("<your-witness-name>")   # built-in `null` if none wired
facts = gather_evidence(source, subject="<effect key>", config=cfg)

# (c) The effect is met ONLY on CONFIRMED — the join is capped by the read-back's
#     accountability (believe_under_floor): a forgeable same-surface read-back
#     (AGENT_AUTHORED) is recorded but structurally CANNOT grant belief.
verdict = witness_effect(EffectClaim(key="<effect key>", narrated="<what agent said>"),
                         (facts,))
# verdict.verdict -> CONFIRMED | REFUTED | UNWITNESSED | NO_CLAIM
# verdict.believe -> True ONLY on CONFIRMED

The load-bearing rule, enforced structurally by believe_under_floor: a read-back on the forgeable floor (AGENT_AUTHORED — the agent re-reading its own surface, a pasted receipt, an mtime) is recorded but structurally incapable of granting belief. So the worst a lying same-surface read-back can do is be ignored, never manufacture a CONFIRMED. Log the gap, never silently skip it: the first time a non-git effect needs witnessing and no dos.evidence_sources driver is wired, emit a one-line log naming the unwitnessed effect — surface it up, never launder it into "goal met."

Step 3 — The gate's verdict is the stop decision

With the gate wired (Step 1), the runtime already enforces the git-phase rung on every stop. Your job in the screenplay is to keep the agent's claimed effects and the goal's effect-list aligned, and to read the gate's verdict honestly:

• All effects CONFIRMED / SHIPPED → the goal is met. The Stop hook emits nothing ({"checked": N, "ok": true} under --json) and the agent stops. This is the only path to "done."
• Any effect source: "none" / REFUTED → the goal is unmet. dos hook stop emits {"decision": "block", "reason": "…"}, the runtime declines to stop, and the reason is fed back as the next instruction — keep working. The agent does not get to overrule this by asserting completion again.
• Any effect UNWITNESSED / NO_CLAIM → you cannot say the goal is met. Surface it for the operator; do not let the agent stop on an effect no accountable witness reached. (The git-phase rung fails safe — a source:"none" is treated as not-shipped, so the gate keeps working rather than passing an unproven claim.)

You can check the gate's reasoning out-of-band, before relying on it, by feeding a synthetic Stop event:

echo '{"transcript_path":"<session.jsonl>"}' | dos hook stop --workspace . --json
# {"ok": false, "reason": "DOS verify: you claimed … shipped, but git has no commit backing it …", "results": [...]}
#   ok:false  → the goal is NOT met; the agent will be kept working.
#   ok:true   → every claimed phase is corroborated; the agent may stop.

This is the same out-of-loop check as dos plan --once / dos commit-audit: a verdict over ground truth, run from outside the loop that wrote the claim.

Anti-patterns

• ❌ Deciding "the goal is met" by re-reading the transcript / the agent's last message. That is consistency, not grounding — the agent judging its own bytes. Decompose into effects and witness each one.
• ❌ Treating "I committed the phase" as the phase shipping. Run dos verify; a source:"none" means git does not back the claim, regardless of the narration.
• ❌ Grepping commit subjects yourself to confirm a ship. The ship-stamp grammar is dos.toml [stamp] data the oracle reads — ask dos verify, do not re-implement the rung (a subject is forgeable; let the oracle weigh the rung).
• ❌ Letting the agent stop on an UNWITNESSED / NO_CLAIM effect "because it probably worked." Abstain surfaces it; it is never a met effect.
• ❌ Wiring dos hook marker when you mean this gate (or vice versa). Marker bounds keep-alive polling; this gate refuses a false done. Opposite triggers.
• ❌ Naming a specific lane, plan dir, ship prefix, or witness backend as a literal — read the active layout from dos doctor --json and resolve witnesses by name.

The one rule under this skill

"The goal is met" is a claim with a byte-author. Let the agent stop only when a witness whose byte-author is not the agent corroborates every effect the goal named. The agent's confidence and its fluent description of success are irrelevant to that gate — which is the whole point: the part that decides the goal is done is never the part being judged.