feat(covenant): signed evidence, capability attenuation, accountable-intermediary modules

[reprewindai-dev]

Summary

Adds three additive, standards-hardened Covenant modules under src/lib/covenant/ — extracted/hardened from reference drafts — plus vitest suites. This is Phase 1: land + prove the primitives. Nothing in the live 9-phase runtime (runtime.ts), routes, governance.ts, safety.ts, or types.ts is touched, so /api/request is unchanged. Wiring these into the pipeline (and any trust-score model change) is a deliberate, design-gated Phase 2.

Each reference draft had a real Ed25519 bug — crypto.createSign('sha256') / key.export({format:'hex'}), which Node rejects for Ed25519. All three modules now reuse the existing ./crypto primitives (generateKeyPair, signMessage, verifyMessage, sha256) with base64-DER keys/signatures, and share one recursive canonical encoder.

evidence-standard.ts

Server-signed, per-agent evidence envelopes (the current runtime uses HMAC/SHA-256 with a single global lastEvidenceHash).

• canonicalEncode() — recursive, lexicographically key-sorted, whitespace-free JSON (the existing hmacHashObject only sorts top-level keys); rejects non-finite numbers, normalizes -0.
• EvidenceGenerator signs each envelope hash with an Ed25519 server key from COVENANT_EVIDENCE_SIGNING_KEY. Fail-closed:

  if (!key && NODE_ENV === "production") throw;   // no silent throwaway key
  // dev only: ephemeral keypair + one warning

• AgentEvidenceChain — one independent chain head per agent (removes the global-head race), plus verifyEvidence, getEvidenceChain, queryEvidenceByAgent/ByTime.

capability-attenuation.ts

Deterministic, signed delegation as an explicit Capability {resource, action, constraints} model — offered alongside the existing trust-score delegation, not replacing it.

• validateAttenuation() proves delegatee ⊆ delegator (and can't loosen max_amount); hasCapability() enforces grant/exclude/constraint/expiry/revocation.
• DelegationRegistry signs delegations (signMessage over canonicalEncode) and does cascading revocation (guards against re-processing already-revoked to terminate cycles).

accountable-intermediary.ts

Signed gateway/proxy decision receipts (new capability — no equivalent today).

• ManagedIntermediary.processRequest() emits a signed IntermediaryReceipt for forwarded | cached | denied(429/403) | queued, committing to the request hash + decision; verifyReceipt() recomputes hash and checks the Ed25519 signature (any field tamper ⇒ invalid).

Testing

• npm test: 42 passed (was 29 on main) — 13 new tests, no new failures. Covers deterministic canonicalization, verify-true, prod fail-closed, tamper-every-section, per-agent chains, attenuation escalation rejection, denial codes, cascade revocation, receipt tamper detection.
• tsc --noEmit, npm run build, npm run lint: the only failures (route-context typegen error; ESLint 10 vs legacy next lint config) reproduce identically on clean main — pre-existing, not introduced here.

Follow-up (Phase 2, not in this PR)

Wire EvidenceGenerator into Phase 7 sealing + forwardEvidence; decide whether capability attenuation supersedes trust-score delegation (data migration); source COVENANT_EVIDENCE_SIGNING_KEY via Coolify. These need design sign-off before touching the live path.

Link to Devin session: https://app.devin.ai/sessions/325c5e1802984dcd9189080f1493b466
Requested by: @reprewindai-dev

Summary by CodeRabbit

• New Features
  • Added verifiable accountability receipts for requests, including forwarding, caching, rate limits, and policy denials.
  • Added delegated permissions with support for constrained capabilities, expiration, verification, and cascading revocation.
  • Added signed execution evidence with request and response integrity checks, authorization details, and chain tracking.
  • Added verification tools to detect tampering and confirm the authenticity of receipts, permissions, and evidence.

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Project	Deployment	Actions	Updated (UTC)
c-api	Error		Aug 3, 2026 11:34pm
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Review failed

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: f3ac3e6b-b429-47e6-9105-d3daa7f47710

📥 Commits

Reviewing files that changed from the base of the PR and between b44ac31 and d61d122.

📒 Files selected for processing (6)

• src/lib/covenant/accountable-intermediary.test.ts
• src/lib/covenant/accountable-intermediary.ts
• src/lib/covenant/capability-attenuation.test.ts
• src/lib/covenant/capability-attenuation.ts
• src/lib/covenant/evidence-standard.test.ts
• src/lib/covenant/evidence-standard.ts

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📝 Walkthrough

Walkthrough

Adds three Covenant modules: signed execution evidence with agent chains, signed intermediary receipts, and attenuated capability delegation. Each module includes verification logic and focused Vitest coverage for tampering, expiry, denial, revocation, and retrieval behavior.

Changes

Evidence standard

Layer / File(s)	Summary
Evidence contracts and canonical commitments src/lib/covenant/evidence-standard.ts, src/lib/covenant/evidence-standard.test.ts	Defines evidence types, signing-key handling, deterministic canonical encoding, and envelope hashing.
Evidence generation and agent chains src/lib/covenant/evidence-standard.ts, src/lib/covenant/evidence-standard.test.ts	Generates and signs evidence, records per-agent chain state, stores records, and tests key exposure and chain linkage.
Evidence verification and queries src/lib/covenant/evidence-standard.ts, src/lib/covenant/evidence-standard.test.ts	Verifies hashes and signatures and supports chain, agent, and time-range queries with tamper tests.

Capability attenuation

Layer / File(s)	Summary
Capability models and attenuation checks src/lib/covenant/capability-attenuation.ts, src/lib/covenant/capability-attenuation.test.ts	Defines capabilities and delegated authority and checks grants, exclusions, expiry, and amount limits.
Signed delegation registry src/lib/covenant/capability-attenuation.ts, src/lib/covenant/capability-attenuation.test.ts	Registers agent keys, creates signed delegations, and verifies delegation signatures and validity.
Revocation and effective capabilities src/lib/covenant/capability-attenuation.ts, src/lib/covenant/capability-attenuation.test.ts	Cascades revocation to downstream delegations and aggregates effective capabilities by agent and audience.

Accountable intermediary

Layer / File(s)	Summary
Receipt schema and request processing src/lib/covenant/accountable-intermediary.ts, src/lib/covenant/accountable-intermediary.test.ts	Produces signed receipts for forwarding, denials, cache hits, and queued requests.
Receipt verification and retrieval src/lib/covenant/accountable-intermediary.ts	Validates receipt algorithms, keys, hashes, and signatures and returns stored receipts.

Estimated code review effort: 5 (Critical) | ~90 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Caller
  participant EvidenceGenerator
  participant AgentEvidenceChain
  participant EvidenceStorage
  Caller->>EvidenceGenerator: submit execution evidence
  EvidenceGenerator->>AgentEvidenceChain: record envelope hash
  AgentEvidenceChain-->>EvidenceGenerator: return chain metadata
  EvidenceGenerator->>EvidenceStorage: store signed evidence
  EvidenceStorage-->>Caller: return evidence

Loading

sequenceDiagram
  participant DelegationRegistry
  participant validateAttenuation
  participant Ed25519
  DelegationRegistry->>validateAttenuation: validate delegated capabilities
  validateAttenuation-->>DelegationRegistry: return validation result
  DelegationRegistry->>Ed25519: sign delegation
  Ed25519-->>DelegationRegistry: return signature
  DelegationRegistry->>Ed25519: verify delegation signature

Loading

sequenceDiagram
  participant Client
  participant ManagedIntermediary
  participant DownstreamServer
  participant ReceiptStorage
  Client->>ManagedIntermediary: process request
  ManagedIntermediary->>DownstreamServer: forward eligible request
  DownstreamServer-->>ManagedIntermediary: return response
  ManagedIntermediary->>ReceiptStorage: store signed receipt
  ReceiptStorage-->>Client: return receipt and response

Loading

Possibly related PRs

• reprewindai-dev/cAPI#6: Related to the shared Covenant evidence and runtime evidence infrastructure.
• reprewindai-dev/cAPI#16: Related to runtime accountability, action outcomes, and evidence-reference audit contracts.

✨ Finishing Touches 💡 1

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• Commit unit tests in branch devin/1785799722-capi-evidence-standard

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🔧 ESLint

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src/lib/covenant/accountable-intermediary.test.ts

Oops! Something went wrong! :(

ESLint: 10.8.0

TypeError [ERR_IMPORT_ATTRIBUTE_MISSING]: Module "file:///.eslintrc.json?mtime=1785801415162" needs an import attribute of "type: json"
at validateAttributes (node:internal/modules/esm/assert:88:15)
at defaultLoadSync (node:internal/modules/esm/load:164:3)
at #loadAndMaybeBlockOnLoaderThread (node:internal/modules/esm/loader:776:12)
at #loadSync (node:internal/modules/esm/loader:796:49)
at ModuleLoader.load (node:internal/modules/esm/loader:762:26)
at ModuleLoader.loadAndTranslate (node:internal/modules/esm/loader:504:31)
at #getOrCreateModuleJobAfterResolve (node:internal/modules/esm/loader:555:36)
at afterResolve (node:internal/modules/esm/loader:603:52)
at ModuleLoader.getOrCreateModuleJob (node:internal/modules/esm/loader:609:12)
at node:internal/modules/esm/loader:628:32

src/lib/covenant/accountable-intermediary.ts

Oops! Something went wrong! :(

ESLint: 10.8.0

TypeError [ERR_IMPORT_ATTRIBUTE_MISSING]: Module "file:///.eslintrc.json?mtime=1785801415162" needs an import attribute of "type: json"
at validateAttributes (node:internal/modules/esm/assert:88:15)
at defaultLoadSync (node:internal/modules/esm/load:164:3)
at #loadAndMaybeBlockOnLoaderThread (node:internal/modules/esm/loader:776:12)
at #loadSync (node:internal/modules/esm/loader:796:49)
at ModuleLoader.load (node:internal/modules/esm/loader:762:26)
at ModuleLoader.loadAndTranslate (node:internal/modules/esm/loader:504:31)
at #getOrCreateModuleJobAfterResolve (node:internal/modules/esm/loader:555:36)
at afterResolve (node:internal/modules/esm/loader:603:52)
at ModuleLoader.getOrCreateModuleJob (node:internal/modules/esm/loader:609:12)
at node:internal/modules/esm/loader:628:32

src/lib/covenant/capability-attenuation.test.ts

Oops! Something went wrong! :(

ESLint: 10.8.0

TypeError [ERR_IMPORT_ATTRIBUTE_MISSING]: Module "file:///.eslintrc.json?mtime=1785801415162" needs an import attribute of "type: json"
at validateAttributes (node:internal/modules/esm/assert:88:15)
at defaultLoadSync (node:internal/modules/esm/load:164:3)
at #loadAndMaybeBlockOnLoaderThread (node:internal/modules/esm/loader:776:12)
at #loadSync (node:internal/modules/esm/loader:796:49)
at ModuleLoader.load (node:internal/modules/esm/loader:762:26)
at ModuleLoader.loadAndTranslate (node:internal/modules/esm/loader:504:31)
at #getOrCreateModuleJobAfterResolve (node:internal/modules/esm/loader:555:36)
at afterResolve (node:internal/modules/esm/loader:603:52)
at ModuleLoader.getOrCreateModuleJob (node:internal/modules/esm/loader:609:12)
at node:internal/modules/esm/loader:628:32

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