fix: SDK server client constructor mismatch — MCP init crash on GCE

[Number531]

Summary

The GCE-deployed server (claude-sdk-server.js) failed to initialize the Agent SDK MCP server, rejecting all research workloads with:

⚠️ Failed to build Agent SDK MCP server: Cannot read properties of undefined (reading 'courtListener')
Agent SDK stream error: Error: Agent SDK MCP server not initialized

Root Cause

Two client constructor mismatches in getClients() (lines 390-391):

Client	Expected Signature	Received	Impact
ComprehensiveAnalysisClient	({ courtListener, secEdgar, federalRegister, uspto })	(exaKey, rateLimiter)	Constructor crash → MCP server null → all workloads blocked
ExaClient	(rateLimiter)	(exaKey, rateLimiter)	exaKey string consumed as rateLimiter; real rateLimiter discarded

Why This Only Affected GCE (Not Local)

Two architecturally different servers exist:

Environment	Entry Point	Client Init
Local (npm start)	index.js → EnhancedLegalMcpServer.js	Constructs ComprehensiveAnalysisClient correctly (lines 220-225)
GCE (Dockerfile)	src/server/claude-sdk-server.js directly	Had broken constructor calls (lines 390-391)

The Dockerfile runs claude-sdk-server.js directly, bypassing index.js. The local MCP stdio server (EnhancedLegalMcpServer) never calls getClients() in the SDK server — they share API client classes but initialize them independently.

Fix

• ExaClient: (exaKey, rateLimiter) → (rateLimiter)
• ComprehensiveAnalysisClient: Moved construction after clients object, passing { courtListener: clients.courtListenerWeb, secEdgar: clients.secWeb, federalRegister: clients.federalRegisterWeb, uspto: clients.usptoWeb } — matching EnhancedLegalMcpServer.js pattern

Commit: d28f483
Version: v4.12.3
Files: src/server/claude-sdk-server.js, CHANGELOG.md

Verification

• Local server unaffected (different entry point)
• GCE rebuild + redeploy
• E2E research workload through frontend

[Number531]

Update: v4.12.4 — EPIPE crash fix

After deploying v4.12.3 (constructor fix), the MCP server initialized successfully (✅ Agent SDK MCP server created with 148 tools) and the Agent SDK query launched. However, the server crashed with:

[FATAL] Uncaught exception: Error: write EPIPE

Root cause: The send() try/catch guards (already on main from SSE hardening) catch synchronous res.write() throws, but Node.js can also emit EPIPE as an async error event on the response object. No res.on('error') handler existed, so the error propagated to uncaughtException → gracefulShutdown() → process.exit(1).

Fix (commit adfdcb5): Added res.on('error', ...) handler near existing res.on('close') to absorb async EPIPE errors and call end() for cleanup.

Verification:

• send() try/catch — catches synchronous throws ✓
• Heartbeat try/catch — catches synchronous throws ✓
• res.on('error') — catches async EPIPE events ✓ (NEW)
• res.on('close') — sets clientDisconnected, calls end() ✓
• Local server unaffected (stdio transport, zero shared streaming code) ✓
• GCE rebuild + redeploy (in progress)
• E2E research workload

[Number531]

Resolved — closing. See CHANGELOG for details.