fix(formatter): offload media conversion from event loop

[wangtaotaotao95]

AgentScope Version

2.0.8 (main at 5ff52f87)

Description

Fixes #2724.

AgentScope's formatter methods are async, but media conversion could perform synchronous downloads or local file reads on the event-loop thread. A slow image, audio, or PDF operation could therefore stall unrelated coroutines for up to the request timeout.

This PR offloads existing synchronous DataBlock conversion helpers through asyncio.to_thread in the OpenAI Chat/Responses, Anthropic, Gemini, Moonshot, Ollama, and xAI formatters. It preserves the current helper APIs and output schemas while moving blocking downloads and file reads away from the event loop.

Regression coverage includes:

• a parametrized remote-download test across six formatter families, which schedules an event-loop callback while a mocked download waits;
• an xAI local-image test proving the file read runs outside the event-loop thread.

Verification:

• Original related formatter suites: 91 passed, 4 subtests passed
• xAI and async regression suites: 23 passed
• All pre-commit hooks on changed files passed, including mypy, black, flake8, and pylint
• No public API or documentation changes

The patch and tests were prepared with AI assistance and manually reviewed and verified.

Checklist

• An issue has been created for this PR
• I have read the CONTRIBUTING.md
• Docstrings are in Google style
• Related documentation update is not applicable; no public API or documented behavior changed
• Code is ready for review

Current-head validation (2026-10-01)

Merged main 72f3f6fa into this branch and resolved the Moonshot import conflict, retaining asynchronous media conversion and all current main behavior. At adc464f8, all formatter suites passed: 150 tests and 4 subtests. All pre-commit hooks on the conflict-resolved Moonshot file passed, and git diff --check passed.

Claim coordination: the previous claimant explicitly released #2724 in favor of this PR: #2724 (comment) . The remaining assignment/guard metadata needs maintainer cleanup.

[wangtaotaotao95]

Rebased onto current main (head 202c165) and reconciled the xAI helper extraction with the async local-file read path.

Validation:

• formatter_remote_media_async_test.py and formatter_xai_test.py — 26 tests passed
• pre-commit on all changed files — all hooks passed
• git diff --check — passed

[github-actions]

Thanks for the pull request. One thing worth sorting out before it is reviewed:

• [Bug]: Remote media downloads in async formatters block the event loop #2724 is claimed by @ZxlDragonDoctor. Please leave it with them while the claim stands.

If you think it belongs here anyway, say so and a maintainer will take a look.

[wangtaotaotao95]

Following up on the PR guard: @ZxlDragonDoctor explicitly released the claim on #2724 after checking this existing PR and confirmed that they have no competing PR for the issue: #2724 (comment) .

The issue still appears assigned to them, so the guard is reading stale claim metadata. Could a maintainer clear the released claim and re-evaluate the guard for this PR? This change continues the existing fix; it does not compete with an active claim.