enhance(#1279): project check_violation_fixture scalar — #1278 locate + #1279 proof compose end-to-end (#1346)

Delivers option (a) from the #1314 maintainer review: thread a fourth flat
scalar check_violation_fixture through the projection so a prohibition authored
at spec-phase machine-proves fail-first and greens through the deterministic
path alone — zero hand-authoring at verify time.

- src/probe-core.cts: Prohibition gains check_violation_fixture?; projectProhibitions
  emits it (both kinds) ONLY for a well-formed descriptor and ONLY when non-empty
  (blank/absent -> projects absent -> producer hard-gates, never a partial green).
- src/prohibition-enforcement.cts: descriptorFromProjection reads it back into
  violationFixture via the same numeric-coercion-safe scalar() normalizer.
- Tests (RED-first, proven non-vacuous by reverting both src edits): CHK-02(#1346)
  projection emit, CHK-08(#1346) read-back, CHK-03(D) example round-trip, the
  fast-check round-trip property extended to the 4th scalar (the contract trek-e
  blocked #1301 on), and a real-subprocess COMPOSE capstone greening end-to-end
  through project -> descriptorFromProjection -> default prover+runner.
- Docs flipped from 'hard-gates until #1346' to 'composes end-to-end': verify-phase.md,
  prohibition-probe.md, spec-phase.md authoring, ADR-550 addendum, changeset.
  #1346 now tracks only the node-test causation residual.

190 affected-suite tests green; eslint + tsc clean; size baseline regenerated.

.changeset/1279-machine-proven-fail-first.md

@@ -5,6 +5,6 @@ pr: 1314
 
 **Test-tier prohibition fail-first is now MACHINE-PROVEN, not caller-attested** — the deferred literal `regression-must-fail-first` property of ADR-550 Decision 4 (the gap #1259 / PR #1273 left as a tracked follow-up) has landed. The `check prohibition-enforcement` producer (`src/prohibition-enforcement.cts`, compiled by `build:lib` to the gitignored `gsd-core/bin/lib/prohibition-enforcement.cjs`) no longer trusts the caller's `failFirst` attestation: before a clean, non-vacuous pass can dispose a `test`-tier prohibition green, the new `defaultProveFailFirst` prover independently RUNS the wired check against a KNOWN VIOLATION and confirms it goes RED. Attestation is gone from the green AND (`passed = proof.provenFailFirst === true && run.passed === true`); any other outcome — passes-on-violation, can't-prove, throws, times out, or no violation source — **hard-gates in BOTH interactive and autonomous modes** (ADR-550 D4 / D3). The evidence record gains a `failFirstProof` field recording HOW fail-first was proven (FF-07). A caller can no longer green a toothless check.
 
-The violation is sourced from a new descriptor field, **`CheckDescriptor.violationFixture`** — an author-supplied path to a known-bad subject. For a `lint-rule` the prover lints that fixture and requires the rule id to appear in the JSON report (the rule must have teeth); for a `node-test` the prover spawns the negative test with the subject injected through the **`GSD_PROHIB_SUBJECT`** env convention and requires a NON-VACUOUS red — `# fail >= 1` AND a failing test named distinctly from the file (`isNonVacuousNodeTestRed`), so a violation fixture that merely CRASHES the test at load is not mistaken for the negative assertion firing red (symmetric with the clean-pass non-vacuity guard). The node-test prover also requires the `violationFixture` to EXIST (resolved against `cwd`) before spawning — a missing/typo'd path fail-CLOSES rather than letting an honest test's ENOENT crash forge a green (symmetric with the lint path's file-result guard). A documented residual — proving the red was *caused by* the violation rather than by the env merely being set — and threading a `check_violation_fixture` scalar through the #1278 projection so the deterministic path can green end-to-end are both tracked as follow-up **#1346**. The `lint-rule` path is fully shippable now and is dogfooded against the in-tree `local/no-source-grep` rule; the `node-test` path ships its mechanism (a fixture-bearing descriptor IS machine-proven) and is exercised by SYNTHETIC temp fixtures — there is no live in-tree `node --test` prohibition to dogfood. `CheckDescriptor.failFirst` is **DEMOTED, not removed** (FF-08): it is kept as a non-authoritative hint so the #1259 route-JSON shape and the `CheckDescriptor` type stay backward-compatible mid-migration, but no path greens on it alone. The green/fail-closed policy in `src/probe-core.cts` (`dispositionForProhibition`, reads only `evidence.length > 0`) is untouched; the evidence array shape is additive. This closes ADR-550's D5d follow-up — see the dated 2026-06-15 ADR-550 addendum. (#1279)
+The violation is sourced from a new descriptor field, **`CheckDescriptor.violationFixture`** — an author-supplied path to a known-bad subject. For a `lint-rule` the prover lints that fixture and requires the rule id to appear in the JSON report (the rule must have teeth); for a `node-test` the prover spawns the negative test with the subject injected through the **`GSD_PROHIB_SUBJECT`** env convention and requires a NON-VACUOUS red — `# fail >= 1` AND a failing test named distinctly from the file (`isNonVacuousNodeTestRed`), so a violation fixture that merely CRASHES the test at load is not mistaken for the negative assertion firing red (symmetric with the clean-pass non-vacuity guard). The node-test prover also requires the `violationFixture` to EXIST (resolved against `cwd`) before spawning — a missing/typo'd path fail-CLOSES rather than letting an honest test's ENOENT crash forge a green (symmetric with the lint path's file-result guard). The deterministic spec→verify path composes end-to-end: a fourth flat scalar **`check_violation_fixture`** is projected by `projectProhibitions` and read back by `descriptorFromProjection` (rides both kinds), so a prohibition authored with all four `check_*` scalars machine-proves fail-first and greens through the projection alone — zero hand-authoring at verify time (#1278 + #1279 + #1346; round-trip pinned by a fast-check property + CHK-03(D) + an end-to-end COMPOSE capstone). One documented residual remains under **#1346**: the node-test proof confirms the fixture exists and the check reds, but cannot generically prove the red was *caused by* the subject's content rather than by the env merely being set. The `lint-rule` path is fully shippable now and is dogfooded against the in-tree `local/no-source-grep` rule; the `node-test` path ships its mechanism (a fixture-bearing descriptor IS machine-proven) and is exercised by SYNTHETIC temp fixtures — there is no live in-tree `node --test` prohibition to dogfood. `CheckDescriptor.failFirst` is **DEMOTED, not removed** (FF-08): it is kept as a non-authoritative hint so the #1259 route-JSON shape and the `CheckDescriptor` type stay backward-compatible mid-migration, but no path greens on it alone. The green/fail-closed policy in `src/probe-core.cts` (`dispositionForProhibition`, reads only `evidence.length > 0`) is untouched; the evidence array shape is additive. This closes ADR-550's D5d follow-up — see the dated 2026-06-15 ADR-550 addendum. (#1279)
 
 **PR-review flag — `GSD_PROHIB_SUBJECT` + `violationFixture` are PROPOSED, renamable conventions.** Both are net-new surface with ZERO live in-tree consumers (no in-tree node-test prohibition yet; node-test proof runs only on synthetic test fixtures, the real dogfood stays the lint-rule). They are forward-looking scaffolding, so a later rename — or replacing the env var with an argv — is a mechanical, zero-migration find/replace. Surfacing them here so the maintainer can **ratify, rename, or replace them at PR review** with no migration cost, exactly as #1278's ADR addendum was reviewed at PR time. The `failFirst` demotion is likewise open to weighing outright removal; the keep-as-hint rationale is recorded in the ADR addendum.

docs/adr/550-spec-phase-probe-contract.md

@@ -113,9 +113,9 @@ This addendum ratifies three contract points:
 
 Net effect on D4: the *guarantee* ("a `test`-tier prohibition is never a silent pass") was preserved at every step — fail-closed-now (#644), genuine-execution (#1259), and now **machine-proven fail-first (#1279)**. A `test`-tier prohibition reaches `green`/`passed` ONLY when the wired check both genuinely, non-vacuously passes AND is independently proven to fail on a violation; every miss/fail/un-provable hard-gates. The decision also lives in `src/prohibition-enforcement.cts` comments, `gsd-core/references/prohibition-probe.md`, `gsd-core/workflows/verify-phase.md`, and the #1279 changeset.
 
-**Review corrections (#1314 maintainer review) — two soundness items, tracked:**
+**Review corrections (#1314 maintainer review) — two soundness items:**
-- **node-test fixture-existence guard (was fail-OPEN).** The node-test prover originally guarded only `if (!fixture)`. A missing/typo'd/stale `violationFixture` path made `GSD_PROHIB_SUBJECT` point at a non-existent file; an honest negative test then threw ENOENT *inside its callback* — a failing test named distinctly from the file — which `isNonVacuousNodeTestRed` accepted as proof, **forging a green from a setup crash** (asymmetric with the lint-rule path, which fail-CLOSES on `< 1` file result). Fixed by requiring `fs.existsSync(fixture)` before spawning (symmetric fail-closed). **Documented residual (#1346):** existence is necessary but not sufficient — a deceptive test that reds merely *because* `GSD_PROHIB_SUBJECT` is set (not because the subject's CONTENT violates) is still accepted; proving causation generically for an arbitrary author-supplied test is not possible, so it is recorded as a constraint, not implied-solved.
+- **node-test fixture-existence guard (was fail-OPEN) — FIXED.** The node-test prover originally guarded only `if (!fixture)`. A missing/typo'd/stale `violationFixture` path made `GSD_PROHIB_SUBJECT` point at a non-existent file; an honest negative test then threw ENOENT *inside its callback* — a failing test named distinctly from the file — which `isNonVacuousNodeTestRed` accepted as proof, **forging a green from a setup crash** (asymmetric with the lint-rule path, which fail-CLOSES on `< 1` file result). Fixed by requiring `fs.existsSync(path.resolve(cwd, fixture))` before spawning (symmetric fail-closed; resolved against the producer's `cwd` to match the child's resolution). **Documented residual (#1346):** existence is necessary but not sufficient — a deceptive test that reds merely *because* `GSD_PROHIB_SUBJECT` is set (not because the subject's CONTENT violates) is still accepted; proving causation generically for an arbitrary author-supplied test is not possible, so it is recorded as a constraint, not implied-solved.
-- **`violationFixture` has no projection source (#1278 ↔ #1279 do not yet compose).** `descriptorFromProjection` reconstructs only `{ kind, target, rule? }`; the projected `check_*` scalars carry **no** `violationFixture`. Since green now *requires* a fixture, a prohibition wired purely through the #1278 deterministic path **always hard-gates (fail-closed, safe)** until a `check_violation_fixture` scalar is threaded through — tracked as **#1346**. Until then green requires a hand-supplied `violationFixture`; `verify-phase.md` now states this explicitly rather than implying the projected path produces greens.
+- **`violationFixture` projection source (#1278 ↔ #1279 now COMPOSE) — DELIVERED.** Initially `descriptorFromProjection` reconstructed only `{ kind, target, rule? }` and the projection carried no fixture, so a prohibition wired purely through the deterministic path always hard-gated. This PR threads a **fourth flat scalar `check_violation_fixture`** through `projectProhibitions` + `descriptorFromProjection` (rides both kinds; mirrors `CheckDescriptor.violationFixture`). A prohibition authored with all four scalars now **machine-proves fail-first and greens end-to-end through the projection alone** (zero hand-authoring) — the round-trip is pinned by a fast-check property + CHK-03(D) + an end-to-end COMPOSE capstone. Fail-closed is preserved: a descriptor with no `check_violation_fixture` (or a blank one) projects absent and hard-gates. The remaining work under #1346 is now just the node-test causation residual above.
 
 ## Addendum (2026-06-15): optional `check` descriptor on the prohibition item — D3 shape extension (#1278)
 

gsd-core/references/prohibition-probe.md

@@ -151,38 +151,39 @@ Splitting these axes keeps the lifecycle enum free of a verification fact and le
 prohibition adapter declare `test | judgment` without forking the shared lifecycle enum that
 the edge-probe's `explicit | backstop` also uses.
 
-## Optional wired-check descriptor (deterministic locate, #1278)
+## Optional wired-check descriptor (deterministic locate + machine-proof, #1278 + #1346)
 
 A `resolved`/`test`-tier prohibition MAY carry an **optional `check` descriptor** that names
 the wired mechanical check, so verify-phase locates it deterministically instead of inventing
 `{kind, target, rule}` each run. The descriptor is captured at spec-phase (soft / optional —
 the author wires it when the negative test or lint rule already exists) and is represented as
-**three flat scalar keys** on the `must_haves.prohibitions` item — never a nested `check: {}`
+**four flat scalar keys** on the `must_haves.prohibitions` item — never a nested `check: {}`
 object:
 
 - `check_kind` — `node-test` | `lint-rule` (which producer mechanism runs the check).
 - `check_target` — the test file (`node-test`) or the file the rule runs against (`lint-rule`).
 - `check_rule` — the `ruleId` to filter on, **lint-rule only** (absent for `node-test`).
+- `check_violation_fixture` — path to a KNOWN-BAD subject the #1279 prover runs the check against to
+  machine-prove fail-first (rides BOTH kinds; for `node-test` it is injected via `GSD_PROHIB_SUBJECT`).
 
 The flat-scalar shape is load-bearing: the shared `parseMustHavesBlock` is a flat parser and a
 nested object would flatten/mangle the round-trip (ADR-550 2026-06-15 addendum; #644 "no parser
 rewrite" precedent). `projectProhibitions` emits these keys **only for a well-formed descriptor**
-(valid `check_kind` + non-empty `check_target`; `check_rule` only on the lint-rule path), and
+(valid `check_kind` + non-empty `check_target`; `check_rule` only on the lint-rule path;
-verify-phase reads them back via `descriptorFromProjection` into the `CheckDescriptor` handed to
+`check_violation_fixture` only when non-empty), and verify-phase reads them back via
-`check prohibition-enforcement`. This closes the **locate** half with **zero manual descriptor
+`descriptorFromProjection` into the `CheckDescriptor` handed to `check prohibition-enforcement`. This
-authoring**. Note the projection carries **no `violationFixture`** (`descriptorFromProjection`
+closes **both** the locate (#1278) and the machine-proof-fixture (#1346) halves with **zero manual
-reconstructs only `{ kind, target, rule? }`); because #1279 machine-proves fail-first against a
+descriptor authoring**: a prohibition authored with all four scalars greens end-to-end through the
-fixture, a prohibition wired purely through this projected path **hard-gates (fail-closed)** until a
+projection alone.
-`check_violation_fixture` scalar is threaded through — tracked as **#1346**. Until then green needs a
-hand-supplied `violationFixture`.
 
 **Fail-closed + backward-compat.** A partial descriptor (`lint-rule` missing `check_rule`), an
-unknown `check_kind`, or an **absent** descriptor on a test-tier prohibition falls through to the
+unknown `check_kind`, an **absent** descriptor, OR a descriptor with **no `check_violation_fixture`**
-producer's existing fail-closed locate — never a silent green. A prohibition with no descriptor
+falls through to the producer's fail-closed paths (`located: false`, or located-but-unprovable) —
-parses and disposes byte-identically to today. `failFirst` is **not** sourced from the
+never a silent green. A prohibition with no descriptor parses and disposes byte-identically to today.
-descriptor and is now **demoted** (machine-proven fail-first DELIVERED in #1279 — no path greens on
+`failFirst` is **not** sourced from the descriptor and is **demoted** (machine-proven fail-first
-attestation alone, FF-08); the `dispositionForProhibition` policy is unchanged. The field that gates
+DELIVERED in #1279 — no path greens on attestation alone, FF-08); the `dispositionForProhibition`
-green and is **not yet projected** is `violationFixture` (follow-up #1346).
+policy is unchanged. Residual (tracked **#1346**): the node-test proof confirms the fixture exists and
+the check goes RED, but cannot generically prove the red was *caused by* the subject's content.
 
 ## Output schema
 

gsd-core/workflows/spec-phase.md

@@ -365,11 +365,16 @@ For each Requirement gathered so far, run the two-stage recall→precision pass:
        - `check_target` — the negative-test file path (for `node-test`), or the path to lint
          (for `lint-rule`).
        - `check_rule` — the eslint rule id (e.g. `local/no-source-grep`); `lint-rule` only.
+       - `check_violation_fixture` (#1346) — path to a KNOWN-BAD subject the wired check is run
+         against to **machine-prove fail-first**; rides BOTH kinds. Capture it to let the item green
+         end-to-end with zero hand-authoring at verify time; for `node-test` the negative test should
+         read its subject from the `GSD_PROHIB_SUBJECT` env var so the prover can inject this fixture.
        This is a **SOFT capture (CHK-04): a `test`-tier prohibition WITHOUT a descriptor is still
        allowed** — if the author cannot yet name the wired check, leave the descriptor empty and
        proceed. It is NOT a hard authoring block; the item simply stays fail-closed/flagged
-       downstream (an absent/partial descriptor → `descriptorFromProjection` null/under-specified
+       downstream (an absent/partial descriptor — or one with no `check_violation_fixture` —
-       → producer fail-closed locate, never green). Do NOT capture `failFirst` here — it is a
+       → `descriptorFromProjection` null/under-specified/fixture-less → producer fail-closed
+       locate-or-unprovable, never green). Do NOT capture `failFirst` here — it is a
        verify-time caller attestation, not a spec-authored field (#1279).
    - **Dismiss (reason)** → mark `dismissed` with a REQUIRED non-empty reason (PROB-05). The
      reason string is the audit trail; silence is not a valid dismissal.
@@ -390,8 +395,8 @@ For each Requirement gathered so far, run the two-stage recall→precision pass:
 written (test or judgment tier); otherwise leave `unresolved`. **`--auto` NEVER auto-dismisses
 a prohibition** — a wrong dismissal is the exact silent failure this probe eliminates (PROB-06,
 the load-bearing safety property). On a `test`-tier auto-resolution, capture the `check_kind` /
-`check_target` / `check_rule` descriptor **only when a wired check is unambiguous**; otherwise
+`check_target` / `check_rule` / `check_violation_fixture` descriptor **only when a wired check is unambiguous**; otherwise
-leave it empty — `--auto` NEVER fabricates a check path (a wrong locate is re-validated and
+leave it empty — `--auto` NEVER fabricates a check path or fixture (a wrong locate is re-validated and
 fails closed at the producer, but a fabricated path is still noise to avoid). Log:
 `[auto] prohibitions: R resolved, U unresolved`.
 
@@ -402,8 +407,8 @@ runs identically for non-Claude / text-mode hosts.
 Populate the `## Prohibitions` section of SPEC.md from the resolved prohibitions (each
 `resolved`/`test` row is a checkable negative acceptance criterion; `resolved`/`judgment`
 rows route to judgment review; `⚠ UNRESOLVED` rows are flagged as assumptions). A
-`resolved`/`test` row ALSO carries its captured `check_kind` / `check_target` / `check_rule`
+`resolved`/`test` row ALSO carries its captured `check_kind` / `check_target` / `check_rule` /
-descriptor when present (so the projection feeds `verify-phase`'s deterministic locate, #1278);
+`check_violation_fixture` descriptor when present (so the projection feeds `verify-phase`'s deterministic locate + machine-proof, #1278 + #1346);
 a `test` row with no captured descriptor is still valid — it stays fail-closed/flagged
 downstream rather than blocking authoring.
 

gsd-core/workflows/verify-phase.md

@@ -70,17 +70,17 @@ Aggregate all must_haves across plans for phase-level verification.
 **Prohibitions (`must_haves.prohibitions`, ADR-550 D3 — the must-NOT sibling block):** When a plan carries `must_haves.prohibitions`, extract each `{ statement, status, verification }` item and route it by `verification` tier in verdict assembly (ADR-550 D4, "B-with-guard", 2026-06-12 maintainer decision). These are NEGATIVE checks (the must-NOT must NOT have happened), distinct from positive `truths`:
 
 - **judgment-tier → mode-dependent soft-gate.** Interactive verify defers each item to the end-of-phase human checkpoint (`human_verify_mode: end-of-phase`). Autonomous verify records a NON-AUTHORITATIVE LLM-judge verdict + a prominent `unverified-prohibition — human review recommended` flag (autonomous completion reads "complete with N flagged prohibitions"). NEVER a silent pass; NEVER a hard halt of an AFK run.
-- **test-tier → ENFORCED via `check prohibition-enforcement` (green on pass, hard-gate on miss/fail).** Accept the `verification: test` value (the SPEC↔must_haves.prohibitions projection contract holds — no forced schema change later). For each test-tier item, the verifier builds `request.check` **DETERMINISTICALLY from the projected descriptor** — it does NOT invent `{ kind, target, rule }`. Read the flat scalar keys `check_kind` / `check_target` / `check_rule` off the `must_haves.prohibitions` item and reconstruct the `CheckDescriptor` via the `descriptorFromProjection` adapter in `prohibition-enforcement` (`descriptorFromProjection(projectedItem)` → `{ kind: check_kind, target: check_target, rule?: check_rule }`). Supply a `violationFixture` (a path to a KNOWN-BAD subject) in the request — it is the field that gates **green**, and it is **NOT sourced from the projection today** (the projected `check_*` scalars carry no fixture; threading a `check_violation_fixture` scalar through is the tracked follow-up **#1346**). So with projection alone the item **hard-gates fail-closed** — green currently requires a hand-supplied `violationFixture`. Do NOT rely on `failFirst`: it is DEMOTED (#1279) and greens nothing on its own. Invoke the producer (CLI surface unchanged):
+- **test-tier → ENFORCED via `check prohibition-enforcement` (green on pass, hard-gate on miss/fail).** Accept the `verification: test` value (the SPEC↔must_haves.prohibitions projection contract holds — no forced schema change later). For each test-tier item, the verifier builds `request.check` **DETERMINISTICALLY from the projected descriptor** — it does NOT invent `{ kind, target, rule }`. Read the flat scalar keys `check_kind` / `check_target` / `check_rule` / `check_violation_fixture` off the `must_haves.prohibitions` item and reconstruct the `CheckDescriptor` via the `descriptorFromProjection` adapter in `prohibition-enforcement` (`descriptorFromProjection(projectedItem)` → `{ kind: check_kind, target: check_target, rule?: check_rule, violationFixture?: check_violation_fixture }`). The `violationFixture` (a path to a KNOWN-BAD subject) is the field that gates **green** and it is **now projected** (`check_violation_fixture`, #1346) — so a prohibition authored with all four scalars greens through the projection alone, **zero hand-authoring at verify time**. Do NOT rely on `failFirst`: it is DEMOTED (#1279) and greens nothing on its own; an item with no projected fixture hard-gates fail-closed. Invoke the producer (CLI surface unchanged):
 
   ```bash
   gsd_run check prohibition-enforcement <request.json>
   ```
 
-  where `<request.json>` carries `{ prohibition, check, mode }` — `check` being the wired mechanical-check descriptor `{ kind: 'node-test' | 'lint-rule', target, rule?, violationFixture, failFirst? }`, with `kind`/`target`/`rule` now sourced from the projected `check_*` scalars (not author/verifier invention — #1278). For `node-test`, `target` (from `check_target`) is the negative-test file path; for `lint-rule`, `target` is the PATH to lint and `rule` (from `check_rule`) is the eslint rule id (e.g. `local/no-source-grep`) — both required (a lint-rule without `rule` is not a valid wired check). `violationFixture` is the author-supplied path to a KNOWN-BAD subject the producer runs the check against to **machine-prove fail-first** (for `node-test`, injected via the `GSD_PROHIB_SUBJECT` env convention — #1279); `failFirst` is a DEMOTED, non-authoritative hint kept only for backward route-JSON shape (no path greens on it alone — FF-08). The producer LOCATES the wired check from the projection, **machine-proves it is fail-first** by running it against the violation and confirming it goes RED, RUNS it for a genuine non-vacuous pass, builds `enforcementEvidence`, and emits the `dispositionForProhibition()` verdict (#1259 + #1278 + #1279, ADR-550 D5d). Fail-first is **machine-proven, not caller-attested** — absent a provable violation the producer fails closed, never falling back to attestation. Route the result by its typed fields:
+  where `<request.json>` carries `{ prohibition, check, mode }` — `check` being the wired mechanical-check descriptor `{ kind: 'node-test' | 'lint-rule', target, rule?, violationFixture, failFirst? }`, with `kind`/`target`/`rule`/`violationFixture` now sourced from the projected `check_*` scalars (not author/verifier invention — #1278 + #1346). For `node-test`, `target` (from `check_target`) is the negative-test file path; for `lint-rule`, `target` is the PATH to lint and `rule` (from `check_rule`) is the eslint rule id (e.g. `local/no-source-grep`) — both required (a lint-rule without `rule` is not a valid wired check). `violationFixture` (from `check_violation_fixture`) is the path to a KNOWN-BAD subject the producer runs the check against to **machine-prove fail-first** (for `node-test`, injected via the `GSD_PROHIB_SUBJECT` env convention — #1279); `failFirst` is a DEMOTED, non-authoritative hint kept only for backward route-JSON shape (no path greens on it alone — FF-08). The producer LOCATES the wired check from the projection, **machine-proves it is fail-first** by running it against the violation and confirming it goes RED, RUNS it for a genuine non-vacuous pass, builds `enforcementEvidence`, and emits the `dispositionForProhibition()` verdict (#1259 + #1278 + #1279, ADR-550 D5d). Fail-first is **machine-proven, not caller-attested** — absent a provable violation the producer fails closed, never falling back to attestation. Route the result by its typed fields:
   - **`status: 'green'`, `flagged: false`** (a genuinely-passing wired negative test / lint rule, `located: true`, non-empty `evidence`) → the item is satisfiable → it can reach **passed**.
   - **missing, non-attested, or genuinely-non-passing check** (`located: false` OR `status: 'unverified'`, `flagged: true`) → **hard-gate**: disposes flagged-unverified, NEVER green, routing to `gaps_found` in BOTH interactive and autonomous modes (a failing mechanical check blocks even AFK; ADR-550 D4 / D3). The deterministic fail-closed default backing every miss/fail is `dispositionForProhibition()` in probe-core (`status: 'unverified'`, `flagged: true` on empty `enforcementEvidence`).
 
-  > **Descriptor source — deterministic locate (#1278, DELIVERED).** The `check` descriptor's `{ kind, target, rule }` is now sourced **deterministically from the projected `check_kind` / `check_target` / `check_rule` scalars** on the `must_haves.prohibitions` item (authored at `/gsd:spec-phase`, projected by `projectProhibitions`, read back via the `descriptorFromProjection` adapter). So the **locate** half closes with **zero manual descriptor authoring** — the verifier no longer invents `{ kind, target, rule }` (removing the spoofable invent-at-verify-time surface; ADR-857 §147 exogenous grading). **Fail-closed is preserved:** an item with NO projected descriptor — or a PARTIAL one (e.g. a `lint-rule` missing `check_rule`) — makes `descriptorFromProjection` return `null` / an under-specified descriptor, which falls through to the producer's existing fail-closed LOCATE (`located: false`) → flagged-unverified, NEVER green, in BOTH modes. **Important — the projection does NOT yet carry a `violationFixture`** (`descriptorFromProjection` reconstructs only `{ kind, target, rule? }`). Because #1279 now machine-proves fail-first against a `violationFixture`, a prohibition wired **purely through this projected path always hard-gates** (fail-closed, safe) until a `check_violation_fixture` scalar is threaded through — the **tracked follow-up #1346**. Until then a green requires the verifier to hand-supply `violationFixture`; `failFirst` is demoted and greens nothing (#1279, DELIVERED).
+  > **Descriptor source — deterministic locate + machine-proof compose (#1278 + #1346, DELIVERED).** The `check` descriptor's `{ kind, target, rule, violationFixture }` is now sourced **deterministically from the projected `check_kind` / `check_target` / `check_rule` / `check_violation_fixture` scalars** on the `must_haves.prohibitions` item (authored at `/gsd:spec-phase`, projected by `projectProhibitions`, read back via the `descriptorFromProjection` adapter). So both halves close with **zero manual descriptor authoring** — the verifier neither invents the locate (#1278) nor hand-supplies the violation fixture (#1346): a prohibition authored with all four scalars machine-proves fail-first and greens end-to-end through the projection alone (removing the spoofable invent-at-verify-time surface; ADR-857 §147 exogenous grading). **Fail-closed is preserved:** an item with NO projected descriptor, a PARTIAL one (e.g. a `lint-rule` missing `check_rule`), OR a descriptor with **no `check_violation_fixture`** makes `descriptorFromProjection` return `null` / an under-specified or fixture-less descriptor, which falls through to the producer's fail-closed paths (`located: false`, or located-but-unprovable) → flagged-unverified, NEVER green, in BOTH modes. `failFirst` is demoted and greens nothing on its own (#1279, FF-08). Residual (tracked **#1346**): the node-test proof confirms the fixture exists and the check goes RED, but cannot generically prove the red was *caused by* the subject's content vs the env merely being set.
 
 **Option B: Use Success Criteria from ROADMAP.md**
 

src/probe-core.cts

@@ -299,6 +299,10 @@ export interface Prohibition {
   check_kind?: 'node-test' | 'lint-rule';
   check_target?: string;
   check_rule?: string;
+  // Optional 4th flat scalar (#1346): the path to a KNOWN-BAD subject the #1279 prover runs the check
+  // against to MACHINE-PROVE fail-first. Projected only alongside a well-formed descriptor; absent ->
+  // the producer hard-gates (green requires a fixture). Mirrors `CheckDescriptor.violationFixture`.
+  check_violation_fixture?: string;
 }
 
 /**
@@ -376,6 +380,13 @@ export function projectProhibitions(
       if (kind === 'lint-rule' && typeof p.check_rule === 'string' && p.check_rule.trim() !== '') {
         entry.check_rule = String(p.check_rule);
       }
+      // `check_violation_fixture` (#1346) rides BOTH kinds — it's what the #1279 prover machine-proves
+      // fail-first against. Emit ONLY a non-empty fixture (a blank one projects absent so green still
+      // hard-gates downstream — never a partial green); meaningless without the descriptor, so it lives
+      // inside this well-formed-descriptor branch.
+      if (typeof p.check_violation_fixture === 'string' && p.check_violation_fixture.trim() !== '') {
+        entry.check_violation_fixture = String(p.check_violation_fixture);
+      }
     }
     out.push(entry);
   }

src/prohibition-enforcement.cts

@@ -90,7 +90,8 @@ export interface CheckDescriptor {
  *   - `null`/`undefined`/non-object input -> `null`.
  *   - `check_kind` ABSENT -> `null` (no descriptor -> producer locates nothing -> fail-closed).
  *   - `check_kind` present -> `{ kind: check_kind, target: check_target }`, adding `rule: check_rule`
- *     ONLY when `check_rule` is a non-empty string.
+ *     ONLY when `check_rule` is a non-empty string, and `violationFixture: check_violation_fixture`
+ *     ONLY when that scalar is a non-empty string (#1346 — composes #1278 locate with #1279 proof).
  *   - `failFirst` is NEVER sourced from the projection — it stays a verify-time caller attestation
  *     (#1279 machine-proves it; out of scope here). The returned descriptor carries no `failFirst`.
  *   - The adapter does NOT strictly validate kind/target/rule: it faithfully reconstructs whatever
@@ -121,6 +122,12 @@ export function descriptorFromProjection(
     const rule = scalar(projected.check_rule);
     if (rule.trim().length > 0) descriptor.rule = rule;
   }
+  // `violationFixture` (#1346) rides BOTH kinds — reconstruct it from `check_violation_fixture` so the
+  // deterministic #1278 locate path and the #1279 machine-proof COMPOSE: a projected fixture lets the
+  // default prover green end-to-end with zero hand-authoring. Absent/blank -> no fixture -> the prover
+  // hard-gates (fail-closed; green requires a fixture), never fabricated.
+  const fixture = scalar(projected.check_violation_fixture);
+  if (fixture.trim().length > 0) descriptor.violationFixture = fixture;
   return descriptor;
 }
 

tests/probe-core.property.test.cjs

@@ -193,6 +193,7 @@ function renderProhibitionsDoc(entries) {
     if (e.check_kind !== undefined) lines.push(`      check_kind: ${e.check_kind}`);
     if (e.check_target !== undefined) lines.push(`      check_target: ${e.check_target}`);
     if (e.check_rule !== undefined) lines.push(`      check_rule: ${e.check_rule}`);
+    if (e.check_violation_fixture !== undefined) lines.push(`      check_violation_fixture: ${e.check_violation_fixture}`);
   }
   lines.push('---', '', 'Body.', '');
   return lines.join('\n');
@@ -216,19 +217,20 @@ const pathScalarArb = fc.array(fc.constantFrom(...PATH_CHARS), { minLength: 1, m
 const numericScalarArb = fc.nat({ max: 9999999 }).map(String);
 const targetArb = fc.oneof(pathScalarArb, numericScalarArb);
 
-// A fully well-formed descriptor item (resolved test-tier); node-test carries no rule.
+// A fully well-formed descriptor item (resolved test-tier); node-test carries no rule. The
+// violation fixture (#1346) rides BOTH kinds and exercises the numeric-coercion path too.
 const wellFormedArb = KIND_ARB.chain((kind) =>
-  fc.record({ target: targetArb, rule: pathScalarArb }).map(({ target, rule }) => {
+  fc.record({ target: targetArb, rule: pathScalarArb, fixture: targetArb }).map(({ target, rule, fixture }) => {
-    const item = { ...BASE_TIER, check_kind: kind, check_target: target };
+    const item = { ...BASE_TIER, check_kind: kind, check_target: target, check_violation_fixture: fixture };
     if (kind === 'lint-rule') item.check_rule = rule;
-    return { item, kind, target, rule: kind === 'lint-rule' ? rule : undefined };
+    return { item, kind, target, rule: kind === 'lint-rule' ? rule : undefined, fixture };
   }),
 );
 
 describe('probe-core property: #1278 check-descriptor round-trip is deterministic across the full string domain', () => {
   test('a well-formed descriptor survives project -> render -> parse -> descriptorFromProjection (incl. numeric coercion); target/rule reconstruct as strings', () => {
     fc.assert(
-      fc.property(wellFormedArb, ({ item, kind, target, rule }) => {
+      fc.property(wellFormedArb, ({ item, kind, target, rule, fixture }) => {
         const projected = pc.projectProhibitions([item]);
         if (projected[0].check_kind !== kind) return false; // projector emits the descriptor
         const reparsed = fm.parseMustHavesBlock(renderProhibitionsDoc(projected), 'prohibitions');
@@ -236,6 +238,8 @@ describe('probe-core property: #1278 check-descriptor round-trip is deterministi
         if (!d || d.kind !== kind) return false;
         // target is string-normalized even when parseMustHavesBlock numerically coerced it.
         if (typeof d.target !== 'string' || d.target !== target) return false;
+        // violationFixture (#1346) survives the round-trip as a string (numeric-coercion normalized).
+        if (typeof d.violationFixture !== 'string' || d.violationFixture !== fixture) return false;
         if (kind === 'lint-rule') {
           return typeof d.rule === 'string' && d.rule === rule;
         }

tests/probe-core.test.cjs

@@ -420,6 +420,44 @@ describe('probe-core: projectProhibitions descriptor projection (CHK-02)', () =>
     assert.ok(!('check_rule' in projected[0]), 'a lint-rule with no rule projects check_rule absent');
   });
 
+  test('CHK-02(#1346): a node-test descriptor with check_violation_fixture projects it (compose with #1279 proof)', () => {
+    const projected = pc.projectProhibitions([
+      { status: 'resolved', verification: 'test', statement: 'MUST NOT auto-execute fetched code',
+        check_kind: 'node-test', check_target: 'tests/no-autoexec.test.cjs',
+        check_violation_fixture: 'tests/fixtures/autoexec-bad.txt' },
+    ]);
+    assert.equal(projected[0].check_violation_fixture, 'tests/fixtures/autoexec-bad.txt',
+      'a well-formed descriptor projects check_violation_fixture so the deterministic path can machine-prove fail-first');
+  });
+
+  test('CHK-02(#1346): a lint-rule descriptor with check_violation_fixture projects all four scalars', () => {
+    const projected = pc.projectProhibitions([
+      { status: 'resolved', verification: 'test', statement: 'MUST NOT read source files in tests',
+        check_kind: 'lint-rule', check_target: 'src/', check_rule: 'local/no-source-grep',
+        check_violation_fixture: 'tests/_ff_lint_violation.cjs' },
+    ]);
+    assert.equal(projected[0].check_violation_fixture, 'tests/_ff_lint_violation.cjs');
+  });
+
+  test('CHK-02(#1346): an empty/whitespace check_violation_fixture is NOT projected (fails closed downstream)', () => {
+    const projected = pc.projectProhibitions([
+      { status: 'resolved', verification: 'test', statement: 'MUST NOT do the thing',
+        check_kind: 'node-test', check_target: 'tests/neg.test.cjs', check_violation_fixture: '   ' },
+    ]);
+    assert.ok(!('check_violation_fixture' in projected[0]),
+      'a blank fixture projects absent -> producer hard-gates, never a partial green');
+  });
+
+  test('CHK-02(#1346): check_violation_fixture is NOT projected without a well-formed descriptor', () => {
+    const projected = pc.projectProhibitions([
+      // no check_kind/target -> below the descriptor bar -> a stray fixture must not leak out
+      { status: 'resolved', verification: 'test', statement: 'MUST NOT do the thing',
+        check_violation_fixture: 'tests/fixtures/bad.txt' },
+    ]);
+    assert.ok(!('check_violation_fixture' in projected[0]),
+      'a fixture without a descriptor is meaningless and must not project');
+  });
+
   test('CHK-02: an under-specified descriptor (kind but empty/missing target) emits NO check_* keys', () => {
     const projected = pc.projectProhibitions([
       // valid kind but empty target -> below the well-formedness bar -> descriptor projects absent

tests/prohibition-enforcement.test.cjs

@@ -731,6 +731,41 @@ describe('prohibition-enforcement REAL runner end-to-end (#1259)', () => {
     assert.equal(result.located, true, 'the descriptor was located; it just could not be proven fail-first');
     assert.equal(result.evidence.length, 0, 'no enforcement evidence on a hard-gate');
   });
+
+  test('COMPOSE (#1346): a prohibition projected WITH check_violation_fixture greens end-to-end through the DEFAULT prover+runner (zero hand-authoring)', (t) => {
+    const enforce = require(ENFORCEMENT_LIB);
+    const pc = require(path.join(__dirname, '..', 'gsd-core', 'bin', 'lib', 'probe-core.cjs'));
+    const dir = createTempDir('prohib-compose-1346-');
+    t.after(() => cleanup(dir));
+    // The #1278 deterministic-locate path + the #1279 machine-proof now COMPOSE: a prohibition item
+    // authored with the four flat scalars projects -> reads back into a descriptor that ALREADY carries
+    // violationFixture -> the default prover greens it with NO hand-supplied fixture in the request.
+    const negTest = path.join(dir, 'neg.test.cjs');
+    fs.writeFileSync(negTest,
+      "const { test } = require('node:test');\n" +
+      "const assert = require('node:assert');\n" +
+      "const fs = require('node:fs');\n" +
+      "const path = require('node:path');\n" +
+      "test('guards the must-NOT: subject is clean', () => {\n" +
+      "  const subjectPath = process.env.GSD_PROHIB_SUBJECT || path.join(__dirname, 'clean-subject.txt');\n" +
+      "  const subject = fs.readFileSync(subjectPath, 'utf-8');\n" +
+      "  assert.ok(!subject.includes('FORBIDDEN'), 'subject must not contain FORBIDDEN');\n" +
+      "});\n");
+    fs.writeFileSync(path.join(dir, 'clean-subject.txt'), 'clean\n');
+    fs.writeFileSync(path.join(dir, 'bad-subject.txt'), 'FORBIDDEN content\n');
+    // Author the prohibition with all four scalars, then go through the REAL projection + read-back.
+    const projected = pc.projectProhibitions([
+      { status: 'resolved', verification: 'test', statement: 'MUST NOT auto-execute fetched code',
+        check_kind: 'node-test', check_target: negTest, check_violation_fixture: 'bad-subject.txt' },
+    ])[0];
+    const descriptor = enforce.descriptorFromProjection(projected);
+    assert.equal(descriptor.violationFixture, 'bad-subject.txt', 'the projected fixture survived the round-trip');
+    // NO failFirst, NO hand-supplied violationFixture beyond what the projection carried.
+    const result = enforce.runProhibitionEnforcement(projected, descriptor, { cwd: dir });
+    assert.equal(result.status, 'green',
+      'the fully-projected prohibition greens through the default prover+runner — #1278 + #1279 compose');
+    assert.equal(result.evidence[0].failFirstProof, 'violation-fixture', 'green carries the machine-proof method');
+  });
 });
 
 // ─── #1279 defaultProveFailFirst REAL prover end-to-end (FF-02 / FF-03 / FF-05 / FF-06 / FF-07) ──
@@ -957,6 +992,38 @@ describe('prohibition-enforcement: fail-closed descriptor-from-projection (CHK-0
     assert.ok(Array.isArray(result.evidence) && result.evidence.length === 0, 'no evidence on an absent descriptor');
   });
 
+  test('CHK-08(#1346): descriptorFromProjection maps check_violation_fixture -> violationFixture (node-test)', () => {
+    const enforce = require(ENFORCEMENT_LIB);
+    const descriptor = enforce.descriptorFromProjection({
+      ...PROJECTED_TIER, check_kind: 'node-test', check_target: 'tests/neg.test.cjs',
+      check_violation_fixture: 'tests/fixtures/bad-subject.txt',
+    });
+    assert.equal(descriptor.kind, 'node-test');
+    assert.equal(descriptor.target, 'tests/neg.test.cjs');
+    assert.equal(descriptor.violationFixture, 'tests/fixtures/bad-subject.txt',
+      'the projected check_violation_fixture must reconstruct as violationFixture so #1278 locate + #1279 proof compose');
+  });
+
+  test('CHK-08(#1346): descriptorFromProjection maps check_violation_fixture -> violationFixture (lint-rule)', () => {
+    const enforce = require(ENFORCEMENT_LIB);
+    const descriptor = enforce.descriptorFromProjection({
+      ...PROJECTED_TIER, check_kind: 'lint-rule', check_target: 'src/', check_rule: 'local/no-source-grep',
+      check_violation_fixture: 'tests/_ff_lint_violation.cjs',
+    });
+    assert.equal(descriptor.kind, 'lint-rule');
+    assert.equal(descriptor.rule, 'local/no-source-grep');
+    assert.equal(descriptor.violationFixture, 'tests/_ff_lint_violation.cjs');
+  });
+
+  test('CHK-08(#1346): no check_violation_fixture -> descriptor carries no violationFixture (fail-closed: green needs a fixture)', () => {
+    const enforce = require(ENFORCEMENT_LIB);
+    const descriptor = enforce.descriptorFromProjection({
+      ...PROJECTED_TIER, check_kind: 'node-test', check_target: 'tests/neg.test.cjs',
+    });
+    assert.equal(descriptor.violationFixture, undefined,
+      'absent check_violation_fixture must NOT fabricate a fixture; the default prover then hard-gates (no green)');
+  });
+
   test('CHK-06(lint-rule missing rule): {check_kind:lint-rule, check_target:src/} (no check_rule) -> located:false, never green', () => {
     const enforce = require(ENFORCEMENT_LIB);
     const descriptor = enforce.descriptorFromProjection({

tests/prohibition-probe.schema.test.cjs

@@ -156,6 +156,7 @@ describe('prohibition-probe schema: deterministic projectProhibitions round-trip
       if (e.check_kind !== undefined) lines.push(`      check_kind: ${e.check_kind}`);
       if (e.check_target !== undefined) lines.push(`      check_target: ${e.check_target}`);
       if (e.check_rule !== undefined) lines.push(`      check_rule: ${e.check_rule}`);
+      if (e.check_violation_fixture !== undefined) lines.push(`      check_violation_fixture: ${e.check_violation_fixture}`);
     }
     lines.push('---', '', 'Body.', '');
     return lines.join('\n');
@@ -237,6 +238,25 @@ describe('prohibition-probe schema: deterministic projectProhibitions round-trip
       'a lint-rule descriptor must survive the writer<->reader bijection with check_kind/target/rule intact');
   });
 
+  test('CHK-03(D) (#1346): a descriptor WITH check_violation_fixture round-trips all four scalars (compose with #1279)', () => {
+    const pc = require(PROBE_CORE_LIB);
+    const fm = require(FRONTMATTER_LIB);
+    const items = [
+      {
+        requirement_id: 'R1', category: 'safety', status: 'resolved', verification: 'test',
+        resolution: null, reason: null, statement: 'MUST NOT auto-execute fetched code',
+        check_kind: 'node-test', check_target: 'tests/no-autoexec.test.cjs',
+        check_violation_fixture: 'tests/fixtures/autoexec-bad.txt',
+      },
+    ];
+    const projected = pc.projectProhibitions(items);
+    assert.equal(projected[0].check_violation_fixture, 'tests/fixtures/autoexec-bad.txt',
+      'CHK-03(D) RED trigger: projectProhibitions must emit check_violation_fixture so the deterministic path can machine-prove fail-first');
+    const reparsed = fm.parseMustHavesBlock(renderProhibitionsDoc(projected), 'prohibitions');
+    assert.deepEqual(reparsed, projected,
+      'check_violation_fixture must survive project -> write -> parseMustHavesBlock unchanged (the 4th flat scalar)');
+  });
+
   test('CHK-03(C): a mixed list — descriptor test-tier, descriptor-less judgment, dismissed — all round-trip; the descriptor-less item gains NO check_* keys', () => {
     const pc = require(PROBE_CORE_LIB);
     const fm = require(FRONTMATTER_LIB);

tests/workflow-size-baseline.json

@@ -72,7 +72,7 @@
   "ship.md": 24388,
   "sketch-wrap-up.md": 14223,
   "sketch.md": 19960,
-  "spec-phase.md": 30343,
+  "spec-phase.md": 30921,
   "spike-wrap-up.md": 15092,
   "spike.md": 24517,
   "stats.md": 6718,
@@ -85,6 +85,6 @@
   "undo.md": 10431,
   "update.md": 21053,
   "validate-phase.md": 10745,
-  "verify-phase.md": 37771,
+  "verify-phase.md": 37821,
   "verify-work.md": 31157
 }