Fix broken idle detection and websocket disconnect handling

[simonrosenberg]

Summary

This PR fixes two critical bugs causing runtime instability as reported in #1633:

1. Broken Idle Time Detection (PRIMARY FIX)

Problem: The runtime-api was killing runtimes that were actively serving requests because it incorrectly calculated them as "idle". The idle time was only updated when events were processed in the conversation service, not when actual HTTP requests were being served.

Solution: Added ActivityTrackingMiddleware that updates the last activity timestamp on every HTTP request. This ensures that the /server_info endpoint accurately reflects actual HTTP activity, allowing runtime-api to correctly detect idle vs active runtimes.

2. Websocket Disconnect Handling (SECONDARY FIX)

Problem: When websocket connections encountered RuntimeError or ConnectionError, these exceptions were re-raised, potentially causing server instability.

Solution: Modified websocket handlers to gracefully handle these errors by logging a warning and returning normally instead of re-raising. Cleanup (unsubscription) still happens in the finally block.

Changes

• middleware.py: Added ActivityTrackingMiddleware class that calls update_last_execution_time() on every HTTP request
• api.py: Added the ActivityTrackingMiddleware to the FastAPI application
• sockets.py: Modified exception handling to gracefully handle RuntimeError and ConnectionError instead of re-raising them
• test_middleware.py: Added tests for the activity tracking middleware
• test_event_router_websocket.py: Updated test to reflect new graceful error handling behavior

Checklist

• If the PR is changing/adding functionality, are there tests to reflect this?
• If there is an example, have you run the example to make sure that it works?
• If there are instructions on how to run the code, have you followed the instructions and made sure that it works?
• If the feature is significant enough to require documentation, is there a PR open on the OpenHands/docs repository with the same branch name?
• Is the github CI passing?

Fixes #1633

@simonrosenberg can click here to continue refining the PR

---

Agent Server images for this PR

• GHCR package: https://github.com/OpenHands/agent-sdk/pkgs/container/agent-server

Variants & Base Images

Variant	Architectures	Base Image	Docs / Tags
java	amd64, arm64	eclipse-temurin:17-jdk	Link
python	amd64, arm64	nikolaik/python-nodejs:python3.12-nodejs22	Link
golang	amd64, arm64	golang:1.21-bookworm	Link

Pull (multi-arch manifest)

# Each variant is a multi-arch manifest supporting both amd64 and arm64
docker pull ghcr.io/openhands/agent-server:bb0eaac-python

Run

docker run -it --rm \
  -p 8000:8000 \
  --name agent-server-bb0eaac-python \
  ghcr.io/openhands/agent-server:bb0eaac-python

All tags pushed for this build

ghcr.io/openhands/agent-server:bb0eaac-golang-amd64
ghcr.io/openhands/agent-server:bb0eaac-golang_tag_1.21-bookworm-amd64
ghcr.io/openhands/agent-server:bb0eaac-golang-arm64
ghcr.io/openhands/agent-server:bb0eaac-golang_tag_1.21-bookworm-arm64
ghcr.io/openhands/agent-server:bb0eaac-java-amd64
ghcr.io/openhands/agent-server:bb0eaac-eclipse-temurin_tag_17-jdk-amd64
ghcr.io/openhands/agent-server:bb0eaac-java-arm64
ghcr.io/openhands/agent-server:bb0eaac-eclipse-temurin_tag_17-jdk-arm64
ghcr.io/openhands/agent-server:bb0eaac-python-amd64
ghcr.io/openhands/agent-server:bb0eaac-nikolaik_s_python-nodejs_tag_python3.12-nodejs22-amd64
ghcr.io/openhands/agent-server:bb0eaac-python-arm64
ghcr.io/openhands/agent-server:bb0eaac-nikolaik_s_python-nodejs_tag_python3.12-nodejs22-arm64
ghcr.io/openhands/agent-server:bb0eaac-golang
ghcr.io/openhands/agent-server:bb0eaac-java
ghcr.io/openhands/agent-server:bb0eaac-python

About Multi-Architecture Support

• Each variant tag (e.g., bb0eaac-python) is a multi-arch manifest supporting both amd64 and arm64
• Docker automatically pulls the correct architecture for your platform
• Individual architecture tags (e.g., bb0eaac-python-amd64) are also available if needed

[github-actions]

Coverage Report •

File	Stmts	Miss	Cover	Missing
openhands-agent-server/openhands/agent_server
api.py	147	49	66%	57, 63, 67–69, 71, 83, 85, 108, 147–149, 151–155, 168, 201, 208–209, 213–216, 218, 230, 238, 243–244, 246–247, 250–253, 255, 261, 265, 271, 279–280, 288–289, 297, 301–302, 304, 310
middleware.py	23	7	69%	27–29, 32–33, 36–37
sockets.py	101	51	49%	50–51, 57–59, 68–70, 76–78, 84–85, 88–89, 93, 107–108, 110–111, 113–115, 118, 120–123, 125–126, 128–132, 135–138, 141–142, 145, 148, 155–156, 170–174, 184
TOTAL	14794	7094	52%

[enyst]

Are we sure about not raising on RuntimeError? 🤔

Tiny nit: we could refactor these as except (exceptions) as e: like the WebSocketDisconnect code above, rather than isinstance

[simonrosenberg]

Closed the PR and make 2 smaller PRs
#1636
#1635