What does a Mejepa verdict look like cryptographically?

Each verdict packet carries the prediction (Pass/Fail/Abstain), the named failure mode on Fail or Abstain, the closest historical exemplar (id and cosine distance), the panel state hash, the Docker oracle report.json SHA-256, the conformal interval, an ed25519 signature, and a SHAKE-256 chain link tied to the previous packet.

Where is the public verification key?

Published at https://mejepa.com/keys. Old keys remain valid for verifying historical verdicts. Key rotation events are themselves signed and chained.

How does an auditor replay the chain offline?

Download the chain. Fetch the public key. Run the offline replay tool. The tool verifies every signature, walks the previous-hash chain, and reports any break. End-to-end in roughly 30 seconds. No Mejepa server is reached — the public key is sufficient.

What is the current ship-gate measurement?

Panel A prediction-oracle correlation = 0.866667 on the 8-of-30 holdout window as of 2026-05-20. Target = 0.95 stable across 4 rolling windows × all Python mutation cells. Panel B (cross-panel, non-overlapping encoders, FSV §1.9) is the sole p0 blocker.

What is Mejepa NOT today?

Not a hosted service. Not cross-language at ship-gate time (Python only today). Not an LLM, not a code-writer, not a fine-tune. Not a verifier for non-code AI outputs. Not a continuous-heuristic 'code quality' scorer. Not HTTP-callable from action paths. FSV §1.8.

Trust & Proof · FSV §1.1, §1.2, §1.8

Trust the chain, not the Oracle.

Every verdict the Oracle emits is signed with ed25519 and chained with SHAKE-256. The public key is published. The chain is replayable offline in roughly 30 seconds. You do not have to trust us to confirm what the Oracle saw — the math, the Docker container, and the public key are enough. A real Oracle shows you how to check her. Below: how the chain works, the live ship-gate, and the fences the Oracle holds on purpose.

The witness chain

Five signed witness types · one append-only chain

The chain links five witness types: verdicts, panel states, training certificates, feedback events, audit events. Each link carries the previous link's SHAKE-256 hash, so tampering with any historical record breaks every subsequent signature. Verification needs only the public key — Mejepa servers are not on the trust path.

Five sealed cream-linen envelopes in a row, connected by a black silk ribbon, anchored on the right by a brass ring engraved 'PUBLIC KEY · OFFLINE 30s'. Each envelope tagged in copperplate: verdict, panel, training cert, feedback event, audit.

What a verdict packet contains

The patch SHA-256 + base file SHA-256
The verdict: Pass, Fail, or Abstain (with OOD reason if applicable)
The Docker oracle report.json SHA-256 — anyone can re-run the container and confirm independently
The named failure mode on Fail or Abstain
The closest historical exemplar (id + cosine distance from the 491-row registry )
The panel state hash (15 slots, SHAKE-256)
The conformal interval
An ed25519 signature
The previous chain link's SHAKE-256 hash and this link's SHAKE-256 hash

How to replay offline

Download the chain from the pilot delivery (today: handed over with the engagement; post-ship-gate: from the buyer's verdict store).
Fetch the public key from https://mejepa.com/keys.
Run the offline replay tool. It walks every link, verifies every signature, and confirms no record was tampered with.

The live ship-gate

Panel A: 0.866667 → target 0.95

We measure the same number every week on the same 8-of-30 holdout from the SWE-bench Lite 300 × 8 corpus. The gap to ship-gate green is 0.083 correlation points on Panel A. Panel B (cross-panel, non-overlapping encoders — issue #405) is unmeasured and is the sole p0 blocker . There is no "soon." The gate fires when the number fires.

A brass-rimmed analog dial. Pointer at 0.866667 on a 0.85-to-0.95 arc. Brass plaque: SHIP-GATE · PANEL A · 8 OF 30 HOLDOUT · 2026-05-20.

What Mejepa is NOT today · verbatim from FSV §1.8

Pre-production · No SLA · No hosted service today · Python-only at ship-gate · FSV §1.8

The fences, named

Not a generative inference engine. No inner LLM. The product is the verifier, not a code-writer.
Not a benchmark harness.
Not a hosted service. Runs locally on operator hardware (aiwonder for production).
Not a Python codebase. Python only shows up as the corpus subject and in tool wrappers.
Not cross-language at ship-gate time. Current gate is Python-only.
Not HTTP-callable from action paths.

Plus, from the API stability statement: "ME-JEPA-Code is pre-production (no SLA, no backwards compatibility). Schema changes → wipe and rebuild. Future: TBD post-ship-gate."

If a vendor says "Mejepa is a hosted SaaS today" or asks for "Mejepa for non-code AI outputs," they are speaking ahead of the FSV plan. The honest answer for those surfaces is on the roadmap page: science risk, not engineering risk.