Review Gauntlet

A graph-based post-implementation review gate — "the done gate". An orchestrator that must not claim done without green reviews spawns this agent once instead of judging trigger rules and parsing verdict sentinels itself. The graph structure makes skipping a lane or misreading a verdict impossible: trigger signals are computed by a script, lanes run as isolated parallel sub-agents, and the final verdict is a deterministic regex gate — an LLM never gets the chance to rationalize past it.

flowchart TD
    parse["parse<br/>(llm: extract request facts)"] --> signals["signals<br/>(script: deterministic diff facts)"]
    parse -. "fallback" .-> pfault["parse_fault<br/>(script: PIPELINE-FAULT marker)"]
    pfault --> gate
    signals --> select["select_lanes<br/>(llm: ADDITIVE-only judgment)"]
    select --> build["build_items<br/>(script: rules floor ∪ additions;<br/>forced lanes override exactly)"]
    select -. "fallback" .-> dlanes["default_lanes<br/>(script: deterministic degraded<br/>selection — wider, never narrower)"]
    dlanes --> build
    build --> mcr["map: code-review"] & madv["map: adversary"] & msec["map: security"] & mpb["map: probe"]
    mcr -->|"over: 0-or-1 items"| rcr[["code-reviewer<br/>(max_attempts: 2)"]]
    madv --> radv[["adversary<br/>(max_attempts: 2)"]]
    msec --> rsec[["security-reviewer<br/>(max_attempts: 2)"]]
    mpb --> rpb[["probe<br/>(max_attempts: 2)"]]
    rcr -. "fallback" .-> lfault["lane_fault<br/>(script: PIPELINE-FAULT lane result,<br/>collected by the map)"]
    radv -. "fallback" .-> lfault
    rsec -. "fallback" .-> lfault
    rpb -. "fallback" .-> lfault
    mcr & madv & msec & mpb --> rgate["retry_gate<br/>(script: fault-only re-run gate;<br/>stash + restore, ≤3 attempts,<br/>wall-clock budget)"]
    rgate -. "_next: retry faulted lanes" .-> build
    rgate --> gate["verdict_gate<br/>(script: sentinel regex — deterministic)"]
    gate --> done(["GAUNTLET: PASS | BLOCKED<br/>(+ GAUNTLET_REVIEW_INCOMPLETE: … when any lane or the pipeline was incomplete)"])

Why a graph

The four independent review lanes existed before this agent — as prompt discipline inside the calling orchestrator: "spawn code-reviewer when the change is broad", "🔴 always blocks", "INCONCLUSIVE is never PASS". Prompt discipline degrades under context pressure: a lane gets skipped, a verdict line gets paraphrased, a missing report reads as "nothing to report". Here those rules are structure:

Lane selection floor is deterministic (build_items.py): code-review always runs; adversary runs when a spec/plan is present; security runs on attack-surface signals (auth/deps/exec paths or diff content) or hardened posture; probe runs when consumer-facing surface changed and a local-run recipe exists. The select_lanes LLM can only widen the set — a false flag never removes a rule-selected lane. forced_lanes from the caller override everything exactly.
Conditional lanes without dynamic routing: each lane is a map node over a 0-or-1-item list — an empty list means the map runs zero branches (map-over-nothing), which is the skip mechanism. All four maps join at the retry gate on equal-length paths; it falls through to the verdict gate, or routes back to build_items for faulted lanes only.
The verdict is a regex, not an opinion (verdict_gate.py): a missing sentinel is a lane FAILURE, never a pass; the critical count from the code-review report's summary line (raw 🔴 count if absent) blocks regardless of its verdict line; a code-review lane whose own verdict line records a pipeline fault blocks (a degraded review is never a pass); the adversary's own degraded-run header (the Criteria: … line directly under its sentinel recording a pipeline fault, died criterion checks, or its verdict script's crash stub) blocks as a pipeline fault, not as a DIVERGES finding; NEEDS-HUMAN without 🔴 passes but is surfaced under Human attention required; probe INCONCLUSIVE blocks with an environment note — it is never treated as PASS or FAIL.
Verdict independence is structural: lanes run as isolated sub-agents with no teammates: flag — no cross-lane messaging, by construction.
Failure fails closed, structurally (fallback: routes + PIPELINE-FAULT markers): every LLM node and lane retries once (max_attempts: 2), then a fallback fires instead of killing the graph — and every fallback degrades toward BLOCKED, never toward a pass. A dead lane becomes a PIPELINE-FAULT: lane result (lane_fault.py) that the gate reports as BLOCKED naming the lane — distinct from SKIPPED (not selected). A dead parse records a fault and jumps straight to the gate (parse_fault.py). A dead select_lanes degrades to a deterministic selection (default_lanes.py): code-review + adversary, plus probe on consumer surface with a local-run recipe, plus security on auth/deps/exec signals or hardened posture, unioned with caller-forced lanes — wider, never narrower. A crashed build_items records a fault so an all-SKIPPED gate still blocks. Fault detection is prefix-anchored — a real review that merely quotes "PIPELINE-FAULT:" flows to the normal sentinel rules. And the GAUNTLET: sentinel is always emitted: even a crashed gate prints GAUNTLET: BLOCKED, never silence.

Fault-only re-runs

retry_gate.py sits between the lane maps and the verdict gate and re-runs only lanes that faulted — a missing report (stood in for by a synthetic PIPELINE-FAULT: <lane> lane produced no report marker so it never renders as SKIPPED), a non-string report, the lane_fault marker, a sentinel-less report, or a nested graph's own degraded-run wording (the code-review verdict line / the adversary's header line directly under its sentinel). A real verdict (DIVERGES, FAIL, INCONCLUSIVE, NEEDS-HUMAN, …) is never re-run: the review's judgment stands. Each lane gets up to 3 attempts, all inside a wall-clock budget (MAX_RETRY_ELAPSED_SECS) sized to fit the graph timeout.

Stash + restore: every lane report that ran this pass is stashed in kept_results; a re-run pass overwrites the untouched lanes' collected results with [], so their stashed reports are restored before the gate. The verdict gate always sees each lane's last report.
Retry never narrows selection: lane selection is not re-run. A re-run pass rebuilds items only for the retried lanes, and the stashed results stand in for the rest.
Exhaustion is recorded, not hidden: a lane still faulted after its attempts or the budget lands in review_incomplete, and its fault flows to the verdict gate as-is.
Crash guards append: the build_items.py and retry_gate.py crash guards append to an existing signals_error rather than overwrite it, and build_items.py preserves the prior lanes_summary.

A non-empty GAUNTLET_REVIEW_INCOMPLETE: line structurally implies GAUNTLET: BLOCKED: the verdict gate forces every lane named in review_incomplete to a BLOCKED row (review incomplete after N attempt(s)) and a matching blocker, so a restored earlier report can never turn an incomplete review into a pass — and malformed review_incomplete bookkeeping is itself recorded as a pipeline fault, never dropped.

Whenever at least one lane (or the pipeline) could not complete, the first line reads GAUNTLET: BLOCKED followed immediately by GAUNTLET_REVIEW_INCOMPLETE: <lane>[, <lane>]. The names are the exhausted lanes from review_incomplete, plus the pipeline pseudo-lane whenever a pipeline-level PIPELINE-FAULT: fired — parse death, or a crash in the builder, the retry gate, the default-lanes fallback, or the verdict gate itself (the default-lanes fallback's crash still runs the widened lanes, so pipeline appears alongside real lane rows). The report gains a ## Review incomplete section naming each exhausted lane with its attempt count; PIPELINE-FAULT lane rows carry ×N when the lane was re-run (N > 1). The named entries are faults to re-run, never code findings; the line can accompany real findings from the other lanes, which still appear under ## Blockers and must be fixed as usual.

Sentinels parsed

Lane	Sentinel	Blocks on
code-reviewer	`Verdict: MERGE-READY \| NEEDS-HUMAN`	critical count from the report's summary line (raw 🔴 count if absent); missing sentinel; own verdict line records a pipeline fault
adversary	`ADVERSARIAL_REVIEW: CONFORMS \| DIVERGES`	DIVERGES; own degraded-run header (pipeline fault, died criterion checks, or its verdict script's crash stub); missing sentinel
security-reviewer	`SECURITY_REVIEW: PASS \| FAIL`	FAIL; missing sentinel
probe	`USAGE_PROBE: PASS \| FAIL \| INCONCLUSIVE`	FAIL; INCONCLUSIVE (environment note); missing sentinel

Spawning it

agent__spawn --agent review-gauntlet --prompt "Post-implementation review gate.

Project: /abs/path/to/repo
Diff: main...HEAD          (a git range, a ref, or 'worktree' for uncommitted changes)
Rigor: production          Security posture: standard

Plan / acceptance criteria:
<paste the criteria the implementation must satisfy — enables the adversary lane>

Local-run recipe / usage suites:
<how to boot the service locally + where existing suites live — enables the probe lane>

Forced lanes: (optional — e.g. 'adversary, probe' to run exactly those)" \
  --variables {"verification_commands": "[\"cargo test --all\", \"cargo clippy -- -D warnings\"]"}

Verification commands are NOT part of the prompt. They are the declared verification_commands graph variable (default '[]'; a JSON array of shell commands as a string, since agent variables arrive as strings), also settable from the CLI:

coyote -a review-gauntlet --agent-variable project_dir /abs/path/to/repo \
  --agent-variable verification_commands '["cargo test --all"]' "<prompt>"

The reply opens with GAUNTLET: PASS or GAUNTLET: BLOCKED (plus the GAUNTLET_REVIEW_INCOMPLETE: line when applicable), followed by a lane status table, the lane-selection reasons, blockers, attention items, and each lane's full report in a collapsible section. On BLOCKED with a GAUNTLET_REVIEW_INCOMPLETE: line: the named lanes never completed — fix any non-fault blockers listed under ## Blockers, then spawn a fresh gauntlet run (a fault is never a code finding). On BLOCKED without it: fix the findings per your own findings-handling rules, then spawn a fresh gauntlet run. On PASS with Human attention required: complete the work but carry those items into your final report verbatim.

Notes

The caller decides whether review is warranted at all (the gauntlet is for non-trivial work — that's why code-review is unconditionally on); the gauntlet decides which of the other lanes apply and what the verdicts mean.
Lane sub-agents get generous finite per-attempt timeouts (see the timeout: on each run_* node) and one retry (max_attempts: 2) inside the lane, then up to 3 attempts of the whole lane from retry_gate.py while the wall-clock budget (MAX_RETRY_ELAPSED_SECS) allows; settings.timeout is derived from that envelope in graph.yaml's comment. A lane that still dies or times out falls back to the lane_fault marker — BLOCKED naming the lane and GAUNTLET_REVIEW_INCOMPLETE, never a silent pass.
The verification_commands variable is forwarded to the adversary lane as a structured inputs: passthrough on run_adversary (a lone {{…}} template lands the raw value in the child's state) — never through the lane prompt and never extracted by parse. The adversary's run_checks stage executes those commands with a shell, which makes the declaration a trust boundary: the prompt also carries plan text pasted from the repo under review, so commands must never be inferred from it, and the engine merges only the keys parse's output_schema.properties declares, so an extra verification_commands key emitted by the LLM is dropped before it reaches state. Undeclared stays undeclared ('[]' ⇒ "none declared"); a declaration that is not a JSON array of strings executes nothing and records a PIPELINE-FAULT, which the adversary lane reports as DIVERGES and the gate as BLOCKED.
Signals failures degrade gracefully: if git can't compute the diff, lane selection falls back to caller context + forced lanes, and the report notes it. The auth-path regex deliberately over-fires (auth(?!or) matches auth/authn/authz/oauth but not "author") — the safe direction, since signals only ever ADD the security lane.
Requires the code-reviewer, adversary, security-reviewer, and probe agents to be installed (they ship with Coyote).

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