fix(tools): merge subagents metrics (TaskToolSet)

[VascoSch92]

Summary

(ref #2180)

Same problem as in #2221

Same solution.

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?

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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:cf83b49-python

Run

docker run -it --rm \
  -p 8000:8000 \
  --name agent-server-cf83b49-python \
  ghcr.io/openhands/agent-server:cf83b49-python

All tags pushed for this build

ghcr.io/openhands/agent-server:cf83b49-golang-amd64
ghcr.io/openhands/agent-server:cf83b49-golang_tag_1.21-bookworm-amd64
ghcr.io/openhands/agent-server:cf83b49-golang-arm64
ghcr.io/openhands/agent-server:cf83b49-golang_tag_1.21-bookworm-arm64
ghcr.io/openhands/agent-server:cf83b49-java-amd64
ghcr.io/openhands/agent-server:cf83b49-eclipse-temurin_tag_17-jdk-amd64
ghcr.io/openhands/agent-server:cf83b49-java-arm64
ghcr.io/openhands/agent-server:cf83b49-eclipse-temurin_tag_17-jdk-arm64
ghcr.io/openhands/agent-server:cf83b49-python-amd64
ghcr.io/openhands/agent-server:cf83b49-nikolaik_s_python-nodejs_tag_python3.12-nodejs22-amd64
ghcr.io/openhands/agent-server:cf83b49-python-arm64
ghcr.io/openhands/agent-server:cf83b49-nikolaik_s_python-nodejs_tag_python3.12-nodejs22-arm64
ghcr.io/openhands/agent-server:cf83b49-golang
ghcr.io/openhands/agent-server:cf83b49-java
ghcr.io/openhands/agent-server:cf83b49-python

About Multi-Architecture Support

• Each variant tag (e.g., cf83b49-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., cf83b49-python-amd64) are also available if needed

[all-hands-bot]

🟢 LGTM - Clean fix for sub-agent metrics isolation. The solution is simple: reset metrics on sub-agent creation, merge back before eviction. Tests verify real behavior without over-mocking. No issues found.

[github-actions]

Coverage Report •

File	Stmts	Miss	Cover	Missing
openhands-tools/openhands/tools/task
manager.py	121	77	36%	64–66, 70–72, 79, 81, 84, 87–88, 92–93, 97, 101–104, 107–109, 111, 135–136, 138–139, 144, 150, 157–158, 163–165, 173, 180, 189–191, 199, 205, 215–216, 218–221, 223, 239–240, 242, 244–245, 248, 250, 254–255, 257–260, 262–270, 272–273, 275, 282–283, 289–290, 292
TOTAL	19103	9676	49%

[enyst]

I'd take this in, thank you, I just left a tiny comment for further thinking

[github-actions]

API breakage checks (Griffe)

Result: Passed

Action log

[github-actions]

Agent server REST API breakage checks (OpenAPI)

Result: Passed

Action log