Consolidate MCP metrics helpers and add regression tests

[YASH-ai-bit]

Summary

This PR consolidates the duplicate MCP metrics helpers by keeping utils/mcp/metrics.ts as the canonical implementation, turning utils/mcp/metric.ts into a compatibility re-export, and adding direct regression coverage for the metrics behavior.

What changed

• kept utils/mcp/metrics.ts as the live MCP metrics implementation

• updated utils/mcp/metrics.ts to track bounded request records in addition to the existing cumulative counters

• preserved the current metrics fields and behavior already used by the MCP API routes

• added compatible observability fields to getMetrics():

  • uptime.startedAt
  • uptime.durationSeconds
  • uptime.durationHuman
  • latency.unit
  • latency.sampleSize
  • latency.window
  • throughput.requestsPerMinute
  • throughput.recentRequests

• replaced utils/mcp/metric.ts with a thin re-export of utils/mcp/metrics.ts so both paths share one state source

• added utils/mcp/__tests__/metrics.test.ts

Why

There were two MCP metrics helper modules with overlapping responsibilities:

• utils/mcp/metrics.ts
• utils/mcp/metric.ts

The live MCP routes already import utils/mcp/metrics.ts, so this PR keeps that file as the canonical implementation and removes the risk of the two modules drifting or maintaining separate state.

The new tests add direct coverage for:

• cumulative request counting
• tool usage tracking
• onboarding rate limiting
• recent-window metrics behavior
• compatibility through the metric.ts re-export

Testing

Ran:

• npm test -- utils/mcp/__tests__/metrics.test.ts utils/mcp/__tests__/auth.test.ts utils/mcp/__tests__/request-proof-server.test.ts

Manual MCP smoke checks:

• GET /api/mcp/status

• POST /api/mcp/onboard

• POST /api/mcp initialize without the required Accept header returns the expected 406

• POST /api/mcp initialize with the required headers succeeds and returns a session id

Notes

• This PR is intended to preserve existing MCP behavior. The current metrics.ts fields remain in place, and the extra metrics fields are additive only.

• Before:

CREATE TABLE IF NOT EXISTS mcp_request_proofs (
  event_id TEXT PRIMARY KEY,
  pubkey TEXT NOT NULL,
  action TEXT NOT NULL,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (event_id)
)

This SQL syntax was throwing error in table creation while I was testing mcp/api, this issue has also been mentioned in #354.

• After:

CREATE TABLE IF NOT EXISTS mcp_request_proofs (
  event_id TEXT NOT NULL,
  pubkey TEXT NOT NULL,
  action TEXT NOT NULL,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (event_id)
);

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