feat(attest): pluggable attester seam with a deterministic sample implementation

[JSONbored]

Summary

The first slice of #9211: the pluggable boundary between collecting an attestation report and assembling the evidence envelope — so the attested-evaluation epic (#8534) can be built and CI-tested before any SEV-SNP-capable hardware exists.

Confidential Containers ships a no-TEE sample-attester path for exactly this reason. Mirroring it here means real hardware arrives as a config change (swap the Attester implementation) rather than as new code on the critical path — which is what turns the current blocker into "hardware-blocked, not code-blocked".

What lands:

• Attester — the swappable interface (kind + async collect), async because every real implementation performs IO.
• createSampleAttester() — deterministic and hardware-free: every field is derived from the request by SHA-256, so the same request yields byte-identical output and an attested-run E2E can assert exact bytes rather than "something was produced".
• assembleAttestationEnvelope() — computes reportData from the binding itself rather than trusting a caller- or attester-supplied value, so the envelope's commitment and the bytes the attester signed over cannot drift apart. Returns { ok: false } (never throws) when collection fails or the result doesn't validate, so a runner can record attestation_failed instead of crashing a completed evaluation.
• SAMPLE_ATTESTATION_MAGIC / isSampleAttestationReport() — a sample-attested envelope stays identifiable as a dev artifact.

Safety posture (the point of the magic prefix): a sample envelope must never be presentable as real evidence. Two independent things stop that — the report carries the magic as its leading plaintext bytes so the verifier (#9212) can name it precisely, and a sample report has no AMD signature chain so cryptographic verification fails regardless. The magic is the honest error message; the missing chain is the actual guarantee.

Pure and infrastructure-free, matching the module family's contract: no IO, no randomness, no wall-clock reads. A real SEV-SNP attester talks to /dev/sev-guest or a CoCo attestation agent and therefore lives in the IO layer that supplies it — that's the follow-up slice, along with the runner and envelope persistence.

Part of #9211 · epic #8534

Retargeted to main now that #9219 has merged.

Validation

• npx vitest run test/unit/attester-engine.test.ts — 13/13 pass
• Coverage on the new module: 100% statements (17/17), 100% branches (11/11) — every arm exercised: the teeTechnology ?? "sev-snp" fallback both ways, all four isSampleAttestationReport rejection paths (non-string, empty, malformed, valid-but-not-sample), invalid-collection, and both the Error and non-Error throw arms.
• npm run test --workspace @loopover/engine — 737/737 (includes the 3 new barrel tests)

Safety

• No secrets, wallets, hotkeys, trust scores, or reward values.
• No new dependencies; node:crypto only, matching the sibling modules.
• No public-surface or behavior change — additive module plus one barrel export line.

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	loopover-ui	70180d9	Commit Preview URL Branch Preview URL	Jul 27 2026, 07:24 AM

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

❌ 4 Tests Failed:

Tests completed	Failed	Passed	Skipped
22661	4	22657	21

View the top 3 failed test(s) by shortest run time

test/integration/orb-relay.test.ts > POST /v1/orb/relay/pull > REGRESSION (#4995): a DB error inside validateOrbRelayEnrollment's own lookup ALSO returns a clean 503 broker_error, not a framework 500 (the earlier of the two DB-touching calls in this handler)

Stack Traces | 0.00867s run time

AssertionError: expected 500 to be 503 // Object.is equality

- Expected
+ Received

- 503
+ 500

 ❯ test/integration/orb-relay.test.ts:1160:24

test/integration/orb-onboarding.test.ts > Central Orb installation registry routes (/v1/internal/orb/installations) > tolerates a list query that omits results (rows.results ?? [])

Stack Traces | 0.0337s run time

SyntaxError: Unexpected token 'I', "Internal S"... is not valid JSON
 ❯ test/integration/orb-onboarding.test.ts:57:14

test/integration/orb-ingest.test.ts > Orb instance registry routes (/v1/internal/orb/instances) > tolerates a list query that omits results (rows.results ?? [])

Stack Traces | 0.0391s run time

SyntaxError: Unexpected token 'I', "Internal S"... is not valid JSON
 ❯ test/integration/orb-ingest.test.ts:427:14

test/integration/orb-relay.test.ts > POST /v1/orb/relay/register > REGRESSION (#4995): a DB error inside validateOrbRelayEnrollment's own lookup ALSO returns a clean 503 broker_error, not a framework 500 (the earlier of the two DB-touching calls in this handler)

Stack Traces | 0.091s run time

AssertionError: expected 500 to be 503 // Object.is equality

- Expected
+ Received

- 503
+ 500

 ❯ test/integration/orb-relay.test.ts:155:24

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