Feat/mship block stream

[Sg312]

Summary

Make mship block stream

Type of Change

• Bug fix

Testing

Manual

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Skipped		May 16, 2026 1:48am

[greptile-apps]

Greptile Summary

This PR adds end-to-end NDJSON streaming support to the Mothership block execution path so long-running headless requests send heartbeats to prevent HTTP proxy timeouts, and assistant content chunks reach the client incrementally.

• route.ts: A new wantsStreamedExecuteResponse guard branches the endpoint into a streaming path that emits an initial heartbeat, forwards text-channel events as chunk events, and closes with a final event. A shared buildExecuteResponsePayload helper deduplicates the response shape.
• mothership-handler.ts: Always requests application/x-ndjson. readMothershipExecuteResponse consumes the NDJSON stream for the non-streaming path; createMothershipStreamingExecution pipes chunk events into a ReadableStream and mutates execution.output on the final event for the streaming path.
• trace-spans.ts: hasUnhandledError now short-circuits for successful mothership spans, preventing contained tool-call failures from bubbling up to mark the workflow as errored.

Confidence Score: 5/5

Safe to merge — the streaming and non-streaming paths are cleanly separated, abort/cleanup handling is symmetric, and the previously flagged reader-lock gap is fixed.

Both the streaming and non-streaming branches have consistent error handling and resource cleanup. The reader lock is properly released via try/finally in both readMothershipExecuteResponse and createMothershipStreamingExecution. Abort signals thread correctly through the new lifecycleAbortController and stream cancel callbacks. Tests cover the heartbeat, chunk, error, and cancel scenarios.

No files require special attention.

Important Files Changed

Filename	Overview
apps/sim/app/api/mothership/execute/route.ts	Adds NDJSON streaming path with heartbeats, chunk forwarding, abort plumbing, and a refactored buildExecuteResponsePayload helper
apps/sim/executor/handlers/mothership/mothership-handler.ts	Adds NDJSON stream consumption helpers, always-on ndjson request headers, and proper reader lock release in all paths
apps/sim/executor/handlers/mothership/mothership-handler.test.ts	Adds tests for heartbeat stream consumption, error surfacing, chunk streaming with metadata, and stream cancellation aborting the fetch
apps/sim/lib/logs/execution/trace-spans/trace-spans.ts	Short-circuits hasUnhandledError for successful mothership spans so contained tool errors don't bubble to the workflow root
apps/sim/lib/logs/execution/trace-spans/trace-spans.test.ts	Adds a test verifying that a successful mothership span with a failed child tool span does not mark the workflow as errored

Sequence Diagram

sequenceDiagram
participant Handler as MothershipBlockHandler
participant Route as POST /api/mothership/execute
participant Lifecycle as runHeadlessCopilotLifecycle
participant Client as Stream Consumer
Handler->>Route: POST (Accept: application/x-ndjson)
Route->>Route: wantsStreamedExecuteResponse true
Route-->>Handler: 200 application/x-ndjson
Route->>Client: type heartbeat
Route->>Lifecycle: runLifecycle(onEvent)
loop Every 15s idle
Route->>Client: type heartbeat
end
loop On text event
Lifecycle-->>Route: text event
Route->>Client: type chunk content
end
Lifecycle-->>Route: result
alt success
Route->>Client: type final data
else failure
Route->>Client: type error
end
Route->>Client: stream close
alt isContentSelectedForStreaming
Handler->>Handler: createMothershipStreamingExecution
Client->>Handler: stream.cancel abortController.abort
else non-streaming
Handler->>Handler: readMothershipExecuteResponse
end

Loading

_{Reviews (3): Last reviewed commit: "Fix" | Re-trigger Greptile}

[Sg312]

@greptile review

[Sg312]

@cursor review

[cursor]

PR Summary

Medium Risk
Adds a new NDJSON streaming mode with heartbeats/chunking and new cancellation paths, which increases complexity in request lifecycle and stream parsing/abort handling (potential for leaks or partial results if mis-handled).

Overview
Adds an optional NDJSON streaming response to POST /api/mothership/execute: callers can request application/x-ndjson (or x-mothership-execute-stream: ndjson) to receive periodic heartbeat events, streamed assistant chunk events, and a terminating final payload instead of waiting for a single JSON response.

Updates the executor’s MothershipBlockHandler to always request NDJSON, parse both JSON and NDJSON responses, and—when ctx.stream selects content—return a StreamingExecution that forwards chunk text while still capturing the final metadata (tokens/tool calls/cost). Abort/cancel handling is tightened so request/stream cancellation propagates through to the underlying Mothership lifecycle and fetch, and tests are expanded to cover heartbeats, chunk streaming, error events, and cancellation behavior.

^{Reviewed by Cursor Bugbot for commit eee2da0. Bugbot is set up for automated code reviews on this repo. Configure here.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit eee2da0. Configure here.}

[Sg312]

@greptile review