refactor: consolidate MCP logic into utils as single source of truth

[khaliqgant]

Summary

• Socket discovery (discoverSocket, detectCloudWorkspace, getCloudSocketPath, discoverAgentName, etc.) moved from MCP's cloud.ts (522 lines) to @agent-relay/utils/discovery.ts — MCP now a thin re-export (41 lines, -92%)
• Error classes (RelayError, DaemonNotRunningError, etc.) moved from MCP's errors.ts to @agent-relay/utils/errors.ts — MCP now a thin re-export (17 lines, -69%)
• SDK enhanced: RelayClient now uses discoverSocket() for cloud-aware socket resolution instead of hardcoded /tmp/agent-relay.sock; uses typed errors (DaemonNotRunningError, ConnectionError) on connect failure
• ~560 lines of duplication eliminated, no breaking changes, all public APIs preserved via re-exports
• Subsumes MCPSocketFixer's socket resolution fix (commit 3a3c095 preserved in consolidated code)

Dependency graph (no cycles)

protocol (no deps)
config → protocol
utils → protocol, config
sdk → protocol, utils
mcp → config, protocol, utils

Test plan

• 206 utils tests pass (51 new: discovery, errors, consolidation verification)
• 50 SDK tests pass (all existing, including cloud-aware socket resolution)
• 102 MCP tests pass (all existing, including 20 discover tests via re-exports)
• 358 total tests, 0 failures
• TypeScript compilation clean for utils, SDK, and MCP packages
• No cyclic dependency issues (verified with turbo)
• Manual verification: MCP tools work end-to-end with daemon
• Manual verification: SDK client connects using discovered socket

🤖 Generated with Claude Code

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 5 additional flags.

[khaliqgant]

Code Review: PR #353 — MCP/SDK Consolidation

Reviewer: CodexReviewer (automated thorough review)
Verdict: APPROVE ✅

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1. Code Correctness & Consolidation Completeness ✅

The consolidation is complete and correctly implemented:

• @agent-relay/utils/discovery.ts (524 lines) — canonical implementation of all socket discovery, cloud workspace detection, agent identity, and cloud API helpers
• @agent-relay/utils/errors.ts (56 lines) — canonical implementation of all 7 error classes (RelayError, DaemonNotRunningError, AgentNotFoundError, TimeoutError, ConnectionError, ChannelNotFoundError, SpawnError)
• @agent-relay/mcp/src/cloud.ts — reduced from 522 lines to 41-line pure re-export (−92%)
• @agent-relay/mcp/src/errors.ts — reduced from 54 lines to 17-line pure re-export (−69%)
• @agent-relay/sdk/src/discovery.ts — new 38-line re-export barrel
• @agent-relay/sdk/src/errors.ts — new 17-line re-export barrel

All re-export modules contain zero implementation logic. No stale duplicate class definitions remain.

2. Duplication Elimination ✅

~560 lines of duplication eliminated — claim verified. Net positive lines accounted for by 404 lines of new tests, 55 lines of re-export barrels, and the unrelated PR audit report.

3. Backwards Compatibility ✅

All public APIs preserved via re-exports. MCP consumers can still import from ./cloud.js and ./errors.js. SDK consumers get new exports at both barrel and subpath imports. package.json exports maps properly configured with types, CJS, and ESM.

4. Dependency Graph — No Cycles ✅

Verified all 5 package.json files. Proper DAG:

protocol (no @agent-relay deps)
config → protocol
utils → protocol, config
sdk → protocol, utils
mcp → config, protocol, utils

No circular dependencies.

5. Test Coverage ✅

• 51 new tests across 3 files: consolidation verification (28), discovery unit tests (16), error class tests (7)
• Existing MCP discover tests updated to reflect existsSync gate removal
• 358 total tests, 0 failures (per CI)

6. Error Handling Improvements ✅

SDK client.ts now uses typed errors: ECONNREFUSED/ENOENT → DaemonNotRunningError, other errors → ConnectionError. Enables instanceof pattern matching for consumers.

7. Minor Observations (Non-blocking)

• discovery.ts doc comment says "consolidated here in the SDK" but it's in utils — cosmetic
• reports/pr-audit-2026-01-30.md is unrelated to consolidation — consider separate PR
• DEFAULT_SOCKET_PATH fallback in sdk/src/client.ts is fine for robustness

8. Trail Trajectory

Recorded: traj_87mr8y2pd0xb — 95% confidence.

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Summary: Well-executed refactoring eliminating significant code duplication with clean dependency graph, maintained backwards compatibility, and thorough test coverage. Recommend merge.

[willwashburn]

heck yeah