Macro-5 Build Postflight Fail-Closed Proof — R2-B2 (2026-06-19)

Date: 2026-06-19 · Workstream: R2-B2-MACRO-5-STAGING-BUILD-AUTHORIZATION-PACKAGE-2026-06-19 (Deliverable 57 of 110) · Editorial revision: rev1 Class: build postflight fail-closed proof · READ-ONLY · NON-ENACTING · NON-AUTHORIZING · NO write performed.

Metadata convention. Editorial revision (rev1) only. AgentData storage revision/content_length authoritative at read time.

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0. Status and non-authorization

STATUS: PASS — engineering / design-only. The postflight proof that the producer failed closed (no fabricated pass). Engineering PASS ≠ authority PASS. Default: HOLD.

1. Purpose

Define the after-build proof that every failure was a no-op + evidence, never a fabricated stamp/certify.

2. Sources / evidence read

Macro-4 bad-input no-digest-pass rule (D53); error candidate (26); B2 error contract refinement (35). Main process, no reader-agents.

3. Accepted baseline (carried)

On failure: no stamp + a structured failure record; fail-open (stamp/certify on bad input) is disqualifying.

4. Evidence / analysis — fail-closed proof obligation

Proof	Postflight must show
every failed stage	produced no candidate stamp
every failure	produced a candidate_error_code/candidate_reject_reason + evidence append
no bad input	created a digest/PASS/stamp/certify (F-OPEN-1…10)
no silent PASS	every PASS has evidence

5. Candidate / requirement / gate / result

A build passes PT-6 only if no fail-open artifact exists for any input. No run occurred (no build); obligation defined. A single fail-open result rejects the build.

6. Owner-gated future work

Running the producer to test fail-closed is Owner-gated (and bad-input tests are separately gated); forbidden now.

7. What remains unresolved

No run; no fail-closed proof exists.

8. Ready for GPT/Codex review

Yes — Codex should confirm a single fail-open result rejects the build.