feat(agent-mesh): port production trust-engine features from internal#68
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… repo Surgically merged internal-only features into existing public agent-mesh: - governance/audit.py: MerkleAuditChain with real SHA-256 hash computation, Merkle tree proofs, and chain verification (replaced stubs) - trust/bridge.py: IATP/Nexus integration with protocol translation (_a2a_to_mcp, _mcp_to_a2a) instead of passthrough stubs - reward/trust_decay.py: InteractionEdge graph tracking, recursive network propagation, RegimeChangeAlert with KL divergence detection - identity/delegation.py: Ed25519 signature verification in delegation chains All public-only features preserved (ScopeChain, UserContext, CloudEvents, etc). Backward-compatible aliases maintained (ChainNode=MerkleNode, AuditChain=MerkleAuditChain). Tests updated to reflect real implementations vs stubs. 1521 tests pass (matching baseline), 0 regressions. Closes #61 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Dependency Review✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.Scanned FilesNone |
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Pull request overview
Ports production-grade “trust engine” features into the public agent-mesh package, upgrading prior stub implementations to real cryptographic audit trails, protocol translation, network-aware trust decay, and delegation-chain verification.
Changes:
- Implement Merkle-based audit chain with SHA-256 hashing, inclusion proofs, and integrity verification.
- Add protocol translation support in the trust bridge (A2A ↔ MCP) with optional external integration imports.
- Expand trust decay into a network-propagating engine with interaction graph tracking and regime-change detection; strengthen scope-chain verification with hash + signature checks.
Reviewed changes
Copilot reviewed 9 out of 9 changed files in this pull request and generated 8 comments.
Show a summary per file
| File | Description |
|---|---|
| packages/agent-mesh/src/agentmesh/governance/audit.py | Replaces audit stubs with SHA-256 hashing + Merkle audit chain, proofs, and export/proof APIs. |
| packages/agent-mesh/src/agentmesh/trust/bridge.py | Adds protocol translation helpers and optional IATP/Nexus imports; updates send_message() to translate when protocols differ. |
| packages/agent-mesh/src/agentmesh/reward/trust_decay.py | Implements interaction graph tracking, propagation, and KL-divergence regime detection in NetworkTrustEngine. |
| packages/agent-mesh/src/agentmesh/identity/delegation.py | Adds link-hash integrity checking and Ed25519 signature verification during scope-chain verification. |
| packages/agent-mesh/tests/test_trust_decay.py | Updates tests to reflect interaction graph recording and propagation behavior. |
| packages/agent-mesh/tests/test_trust.py | Updates tests to assert translation helpers exist and map fields as expected. |
| packages/agent-mesh/tests/test_services.py | Updates audit service tests to expect a computed Merkle root. |
| packages/agent-mesh/tests/test_governance.py | Updates governance tests to expect real hashes, Merkle roots, and proofs. |
| packages/agent-mesh/tests/test_coverage_boost.py | Adds async translation tests for _translate() and passthrough behavior. |
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| identity = self.known_identities.get(link.parent_did) | ||
| if identity is None: | ||
| return True # Graceful fallback — can't verify without identity | ||
| signable_data = f"{link.parent_did}:{link.child_did}:{','.join(sorted(link.delegated_capabilities))}" |
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The signed payload (signable_data) does not include previous_link_hash, link_id, depth, timestamps, or the computed link_hash. This allows replay/cut-and-paste of a valid signature onto a different chain by changing previous_link_hash and recomputing link_hash (hash is not keyed). Consider signing the canonical bytes of the full link (or at least signing link.compute_hash() / previous_link_hash) so the signature actually binds the link into its chain context.
| signable_data = f"{link.parent_did}:{link.child_did}:{','.join(sorted(link.delegated_capabilities))}" | |
| # Sign and verify the canonical hash of the full link so the signature | |
| # is bound to the link's chain context (including previous_link_hash, depth, etc.). | |
| signable_data = link.compute_hash() |
| from modules.iatp import IATPClient, IATPMessage, TrustLevel | ||
| from modules.nexus import NexusClient, ReputationEngine | ||
| AGENT_OS_AVAILABLE = True | ||
| except ImportError: | ||
| # Fallback if agent-os not installed yet (for development) | ||
| AGENT_OS_AVAILABLE = False | ||
| IATPClient = None | ||
| NexusClient = None |
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The optional modules.iatp / modules.nexus imports are unused in this file, which will trigger Ruff F401 during lint. Additionally, the except ImportError fallback only defines IATPClient/NexusClient but not the other imported names, which could lead to NameError if they’re referenced later. Consider removing these imports until they’re needed, or guard them behind TYPE_CHECKING / define consistent sentinels for all imported symbols and import from the actual public package names (not modules.*).
| from modules.iatp import IATPClient, IATPMessage, TrustLevel | |
| from modules.nexus import NexusClient, ReputationEngine | |
| AGENT_OS_AVAILABLE = True | |
| except ImportError: | |
| # Fallback if agent-os not installed yet (for development) | |
| AGENT_OS_AVAILABLE = False | |
| IATPClient = None | |
| NexusClient = None | |
| from modules.iatp import IATPClient, IATPMessage, TrustLevel # noqa: F401 | |
| from modules.nexus import NexusClient, ReputationEngine # noqa: F401 | |
| AGENT_OS_AVAILABLE = True | |
| except ImportError: | |
| # Fallback if agent-os not installed yet (for development) | |
| AGENT_OS_AVAILABLE = False | |
| IATPClient = None | |
| IATPMessage = None | |
| TrustLevel = None | |
| NexusClient = None | |
| ReputationEngine = None |
| from agentmesh.constants import TRUST_SCORE_DEFAULT, TRUST_SCORE_MAX | ||
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| logger = logging.getLogger(__name__) | ||
| from collections import Counter, defaultdict | ||
| from dataclasses import dataclass, field | ||
| from typing import Any, Callable, Dict, List, Optional, Tuple |
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There’s an import (from collections import Counter, defaultdict) after the logger = logging.getLogger(__name__) statement, which violates E402 (“module level import not at top of file”) and will be flagged by the repo’s ruff check --select E,F,W lint step. Move the collections import up with the other imports (or add it before any non-import statements).
| """Return (peer_did, interaction_weight) pairs for *agent_did*.""" | ||
| neighbors: List[Tuple[str, float]] = [] | ||
| for (f, t), edge in self._edges.items(): | ||
| if f == agent_did: | ||
| neighbors.append((t, edge.weight)) | ||
| elif t == agent_did: | ||
| neighbors.append((f, edge.weight)) |
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InteractionEdge is documented as a directed edge, but get_neighbors() treats edges as bidirectional by returning both outgoing neighbors (from_did → to_did) and incoming neighbors (to_did → from_did). Either update the documentation/types to reflect an undirected interaction graph, or adjust neighbor traversal/propagation to respect directionality.
| """Return (peer_did, interaction_weight) pairs for *agent_did*.""" | |
| neighbors: List[Tuple[str, float]] = [] | |
| for (f, t), edge in self._edges.items(): | |
| if f == agent_did: | |
| neighbors.append((t, edge.weight)) | |
| elif t == agent_did: | |
| neighbors.append((f, edge.weight)) | |
| """Return (peer_did, interaction_weight) pairs for *agent_did*. | |
| Neighbors are defined via outgoing directed edges (from_did -> to_did). | |
| """ | |
| neighbors: List[Tuple[str, float]] = [] | |
| for (f, t), edge in self._edges.items(): | |
| if f == agent_did: | |
| neighbors.append((t, edge.weight)) |
| "resource": self.resource, | ||
| "data": self.data, | ||
| "outcome": self.outcome, | ||
| "previous_hash": self.previous_hash, |
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AuditEntry.compute_hash() currently omits several mutable fields (e.g., target_did, policy_decision, matched_rule, trace_id, session_id) from the hashed payload. That means those fields could be altered without verify_hash() detecting tampering. Include all entry fields that should be integrity-protected (or explicitly document/justify exclusions).
| "resource": self.resource, | |
| "data": self.data, | |
| "outcome": self.outcome, | |
| "previous_hash": self.previous_hash, | |
| "resource": self.resource, | |
| "target_did": self.target_did, | |
| "data": self.data, | |
| "outcome": self.outcome, | |
| "policy_decision": self.policy_decision, | |
| "matched_rule": self.matched_rule, | |
| "previous_hash": self.previous_hash, | |
| "trace_id": self.trace_id, | |
| "session_id": self.session_id, |
| "outcome": self.outcome, | ||
| "previous_hash": self.previous_hash, | ||
| } | ||
| canonical = json.dumps(data, sort_keys=True) |
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json.dumps(data, sort_keys=True) in compute_hash() will raise TypeError if self.data contains non-JSON-serializable values (e.g., bytes, datetime). Since AuditEntry.data is a free-form dict, consider using a stable serialization that can handle common non-JSON types (e.g., default=str / Pydantic’s JSON encoding) so audit logging can’t fail at runtime on otherwise valid entries.
| canonical = json.dumps(data, sort_keys=True) | |
| canonical = json.dumps(data, sort_keys=True, default=str) |
| if not proof: | ||
| return None | ||
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| return { | ||
| "entry": entry.model_dump(), | ||
| "merkle_proof": proof, | ||
| "merkle_root": self._chain.get_root_hash(), | ||
| "verified": self._chain.verify_proof( | ||
| entry.entry_hash, proof, self._chain.get_root_hash() |
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AuditLog.get_proof() treats an empty proof list as falsy (if not proof:) and returns None. For a single-entry Merkle tree, a valid inclusion proof is typically the empty list (root == leaf), so this would incorrectly report “no proof”. Check proof is None instead, and consider separately validating that merkle_root is not None before calling verify_proof().
| if not proof: | |
| return None | |
| return { | |
| "entry": entry.model_dump(), | |
| "merkle_proof": proof, | |
| "merkle_root": self._chain.get_root_hash(), | |
| "verified": self._chain.verify_proof( | |
| entry.entry_hash, proof, self._chain.get_root_hash() | |
| # A valid Merkle proof may be an empty list (e.g., single-entry tree), | |
| # so only treat None as "no proof". | |
| if proof is None: | |
| return None | |
| merkle_root = self._chain.get_root_hash() | |
| # If there is no Merkle root, we cannot verify the proof. | |
| if merkle_root is None: | |
| return None | |
| return { | |
| "entry": entry.model_dump(), | |
| "merkle_proof": proof, | |
| "merkle_root": merkle_root, | |
| "verified": self._chain.verify_proof( | |
| entry.entry_hash, proof, merkle_root |
| identity = self.known_identities.get(link.parent_did) | ||
| if identity is None: | ||
| return True # Graceful fallback — can't verify without identity | ||
| signable_data = f"{link.parent_did}:{link.child_did}:{','.join(sorted(link.delegated_capabilities))}" |
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_verify_link_signature() currently returns True when the parent identity is unknown (identity is None). If ScopeChain.verify() is used for authorization decisions, this is effectively fail-open and allows forged delegation links to validate as long as the attacker omits/avoids known identities. Consider failing closed by default (returning False with an error), or making this behavior explicitly configurable (e.g., require_signatures=True).
Summary
Surgically merges production trust-engine features from the internal repo into the public agent-mesh package. Unlike other modules where internal was a superset, the public agent-mesh has significantly diverged (97 files vs 17 internal), so this required careful feature merging rather than file replacement.
Changes
governance/audit.py — Cryptographic Audit Trail
trust/bridge.py — Protocol Translation
reward/trust_decay.py — Network Propagation
ecord_interaction()\ (was no-op)
identity/delegation.py — Signature Verification
Tests
Closes #61