feat: APS-AgentMesh adapter — structural authorization gates

[aeoess]

APS-AgentMesh Integration

Responds to @imran-siddique's invitation in #478.

Bridges Agent Passport System (APS) structural authorization into AGT's PolicyEngine as external trust signals.

What this PR adds

packages/agentmesh-integrations/aps-agentmesh/ — a new integration package with:

Component	Purpose
APSPolicyGate	Injects APS PolicyDecision into AGT evaluate(action, context)
APSTrustBridge	Maps APS passport grades (0-3) to AGT trust scores (0-1000)
APSScopeVerifier	Validates APS delegation scope chains for task assignment
aps_context()	Builds AGT-compatible context dict from APS artifacts

Architecture

APS governs between processes (cryptographic proof of authorization scope). AGT governs inside the process (policy evaluation, trust scoring). APS structural authorization = hard constraint (gate). AGT behavioral trust = soft signal.

AGT policy rule example

- name: require-aps-authorization
  type: capability
  conditions:
    aps_decision.verdict: 'permit'
  allowed_actions:
    - 'deploy.*'

Tests

17 tests covering: decision parsing, scope chain validation, trust bridging, policy gate context building, scope verification (prefix match, wildcard, depth, budget), and AGT context shape compatibility.

Next steps from #478

1. ✅ Draft PR with minimal APS adapter (this PR)
2. Define interface contract for consuming APS PolicyDecision artifacts
3. Add cross-verification tests using shared decision artifact format
4. Map Entity Verification v1.0 to did:agentmesh: DID scheme

APS: aeoess.com | SDK v1.29.1 (1,919 tests) | MCP v2.19.0 (125 tools) | Paper

[imran-siddique]

Architecturally sound adapter — clean separation of APS hard gates vs AGT soft signals. One blocking issue:

Critical: Signature verification silently degrades to format-only check
\�erify_aps_signature()\ falls back to accepting any 128-char hex string when PyNaCl is absent. Since
acl\ is not in required dependencies, the default install always uses this insecure path. Must fail closed:
\\python
except ImportError:
return False # Cannot verify without nacl
\\

Also:

• Pin \�gent-passport-system>=0.7.0,<0.8.0\ (unbounded external dep)
• Remove unused \hashlib\ and \ ime\ imports
• Add input validation on \passport_grade\ (invalid values silently accepted)
• Trim promotional content in README to match style of other integration packages
• Add tests for \�erify_aps_signature\ (the critical path has zero coverage)

Good work overall — the fail-closed defaults on APSDecision and the zero-dep core are well done.

[aeoess]

@imran-siddique — all six items addressed in e7f8423. Thank you for the thorough review.

1. CRITICAL (fail closed): verify_aps_signature() now returns False when PyNaCl is absent. No more format-only fallback.

2. Pinned dep: agent-passport-system>=0.7.0,<0.8.0

3. Unused imports: Removed hashlib and time.

4. passport_grade validation: aps_context() raises ValueError on invalid grades (must be 0, 1, 2, or 3).

5. README trimmed: Replaced promotional section with minimal links.

6. Tests added: 5 new tests covering verify_aps_signature (fail-closed without nacl, bad signature, empty inputs) and passport_grade validation (invalid value, negative value). 22 total passing.

[aeoess]

@imran-siddique — all six points addressed across two commits (e7f8423 + f8d4ea5):

1. verify_aps_signature fail-closed — return False on ImportError. No silent degradation.
2. Dep pinned — agent-passport-system>=0.7.0,<0.8.0
3. Unused imports removed — hashlib and time cleaned up
4. passport_grade validation — ValueError for values outside 0-3
5. README trimmed — removed architectural positioning language, added install section, matches integration package style
6. 3 new signature tests (25 total): valid roundtrip, wrong key rejects, tampered data rejects. All require PyNaCl — skip gracefully when absent.

The fail-closed fix was the right call. Format-only verification creates false confidence — worse than no verification.

[aeoess]

@imran-siddique — just checking if the two fix commits (e7f8423 + f8d4ea5) address everything from your review. Happy to adjust if any points need further work.

[imran-siddique]

All 6 review items verified as addressed:

1. verify_aps_signature() now returns False on ImportError (fail-closed)
2. agent-passport-system pinned to >=0.7.0,<0.8.0
3. Unused hashlib/time imports removed
4. passport_grade validated with ValueError
5. README promotional content trimmed
6. Signature verification tests added (6 tests)

Clean architecture, good test coverage (25 tests), zero required dependencies. LGTM.

Note: PR is still in Draft — please mark as Ready for Review to proceed with merge.

[aeoess]

@imran-siddique — thank you for the thorough review. Marked as ready.

One follow-up after merge: the dep pin is currently >=0.7.0,<0.8.0. We shipped v0.8.0 today with BYOI interop (did:key, SPIFFE, OAuth, VC wrapper). Happy to open a follow-up PR bumping to >=0.8.0 once this lands — the interop modules let the AGT adapter bridge to external identity systems without custom code.