fix: serialize Laminar span_context UUIDs as strings for JSON compatibility

[neubig]

Summary

Fixes a bug introduced in PR #1988 where Laminar.get_laminar_span_context_dict() returns uuid.UUID objects which are not JSON serializable, causing all PR review workflows to fail with:

Object of type UUID is not JSON serializable

Root Cause

PR #1988 added code to capture span context for trace continuation:

span_context = Laminar.get_laminar_span_context_dict()

However, get_laminar_span_context_dict() returns a dict with uuid.UUID objects (not strings), which fails when json.dump() is called.

Fix

Use get_laminar_span_context().model_dump(mode="json") instead, which properly serializes UUIDs as strings:

laminar_span_context = Laminar.get_laminar_span_context()
span_context = (
    laminar_span_context.model_dump(mode="json")
    if laminar_span_context
    else None
)

Impact

This bug caused 100% of PR review workflows using SDK code with PR #1988 to fail. After this fix, PR reviews should succeed again.

Testing

Added a test to verify trace data with span_context is JSON serializable, which would have caught this bug before merge.

@neubig 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:9167399-python

Run

docker run -it --rm \
  -p 8000:8000 \
  --name agent-server-9167399-python \
  ghcr.io/openhands/agent-server:9167399-python

All tags pushed for this build

ghcr.io/openhands/agent-server:9167399-golang-amd64
ghcr.io/openhands/agent-server:9167399-golang_tag_1.21-bookworm-amd64
ghcr.io/openhands/agent-server:9167399-golang-arm64
ghcr.io/openhands/agent-server:9167399-golang_tag_1.21-bookworm-arm64
ghcr.io/openhands/agent-server:9167399-java-amd64
ghcr.io/openhands/agent-server:9167399-eclipse-temurin_tag_17-jdk-amd64
ghcr.io/openhands/agent-server:9167399-java-arm64
ghcr.io/openhands/agent-server:9167399-eclipse-temurin_tag_17-jdk-arm64
ghcr.io/openhands/agent-server:9167399-python-amd64
ghcr.io/openhands/agent-server:9167399-nikolaik_s_python-nodejs_tag_python3.12-nodejs22-amd64
ghcr.io/openhands/agent-server:9167399-python-arm64
ghcr.io/openhands/agent-server:9167399-nikolaik_s_python-nodejs_tag_python3.12-nodejs22-arm64
ghcr.io/openhands/agent-server:9167399-golang
ghcr.io/openhands/agent-server:9167399-java
ghcr.io/openhands/agent-server:9167399-python

About Multi-Architecture Support

• Each variant tag (e.g., 9167399-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., 9167399-python-amd64) are also available if needed

[all-hands-bot]

🟡 Acceptable - Works but could be cleaner

Linus-Style Analysis:

This fix is pragmatic and direct - you identified a real production bug (100% PR review failure) and fixed it without over-engineering. The solution is simple: use the proper serialization method instead of the broken one.

VERDICT: ✅ Worth merging - Core logic is sound, one minor test improvement suggested

KEY INSIGHT: This is how bug fixes should be done - minimal change, direct solution, test to prevent regression. The only gap is demonstrating why the old code was broken.

[enyst]

Thank you!