Debug gRPC Connection

Overview

The Bindu core (Python) runs a gRPC server on port 3774 that SDKs connect to via RegisterAgent and Heartbeat. After registration, the core calls back into the SDK's own gRPC server (ephemeral port) via HandleMessages. Most connection bugs are in that handshake.

See docs/grpc/overview.md for the full message flow and docs/grpc/limitations.md for known unimplemented behaviors.

Inputs

• Which end is reporting the failure: core logs vs. SDK logs.
• The exact error message and/or symptom.
• Recent commits touching proto/, bindu/grpc/, or sdks/typescript/src/.

Safety

• Do not modify files under bindu/grpc/generated/ or sdks/typescript/src/generated/ to "make the error go away". Proto drift is the underlying problem — fix it with the regenerate-grpc-stubs skill.
• Do not bypass the heartbeat mechanism. The core relies on heartbeats to clean up dead-agent registrations.
• Do not assume the SDK is at fault before inspecting core logs — the core is the ground truth for registration state.

Execution Contract

1. Confirm both processes are alive and bound to expected ports.
2. Inspect core logs for the registration handshake.
3. Probe the core directly with grpcurl.
4. Check for proto drift.
5. Verify SDK heartbeat timing.
6. Consult limitations doc before filing a bug.

Steps

1. Confirm both processes and ports

lsof -ti:3773 -ti:3774
ps aux | grep -E '(bindu|node.*agent|python.*bindu)' | grep -v grep

• 3773 missing → HTTP/A2A server never started. Check for port clash (lsof -i:3773).
• 3774 missing → core started without --grpc. Restart with bindu serve --grpc.
• SDK process missing → it crashed. Check its own logs for a stacktrace.

2. Inspect core logs

Filter for the [bindu-core] prefix. Meaningful signals:

3. Probe the core with grpcurl

# List services — confirms the core is accepting connections
grpcurl -plaintext -proto proto/agent_handler.proto localhost:3774 list

# Synthetic heartbeat — confirms the service is bound
grpcurl -plaintext -proto proto/agent_handler.proto \
  -d '{"agent_id":"test","timestamp":1234567890}' \
  localhost:3774 bindu.grpc.BinduService.Heartbeat

• list fails with connection refused → server not bound (check step 1).
• list works but Heartbeat errors → proto mismatch or handler crash. Read the error body carefully.

4. Check for proto drift

# Any proto changes without matching generated-tree changes?
git log --oneline -10 -- proto/
git log --oneline -10 -- bindu/grpc/generated/ sdks/typescript/src/generated/

If the proto moved but the generated trees didn't — stubs are stale. Run the regenerate-grpc-stubs skill.

5. Verify SDK heartbeat timing

SDKs must send Heartbeat every 30 seconds after RegisterAgent. TypeScript SDK heartbeat logic lives in sdks/typescript/src/client.ts.

Common bugs:

• Heartbeat interval never started (check the setInterval call).
• Heartbeat errors swallowed silently (check for try/catch around the call).
• Process exits between heartbeats (Node.js event loop starved).

6. Consult limitations

Before filing a bug, confirm the behavior isn't documented as known-missing in docs/grpc/limitations.md. Things currently not implemented:

• Streaming responses (HandleMessagesStream)
• TLS / mTLS (localhost only is safe)
• Automatic SDK reconnection
• Connection pooling in GrpcAgentClient

Never do

• Never edit generated stubs to silence a proto drift error. Regenerate instead.
• Never disable heartbeats to avoid "agent silently died" logs — that's the error reporting the real issue.
• Never run the core without --grpc and expect SDKs to work. There is no fallback path.
• Never deploy to non-localhost without mTLS — see docs/MTLS_DEPLOYMENT_GUIDE.md.