feat(btw): deliver background results to the originating request

[YUZHEthefool]

Preflight

• Existing Issues and PRs were searched.
• This follows the current-branch, no-legacy, Python 3.14+ policy.
• Exactly one Agent note is provided by the actual author.

Problem

A detached task is only useful if its result reaches the original request and the request's resources survive until delivery completes.

Proposal

Deliver background results through the existing response decoration and sending stages, preserving the originating request identity. Release temporary files and event registrations after completion, failure, or cancellation.

Design: PR #28 and its English proposal. Parent: P / #122. PR #28 is documentation only; this issue tracks follow-up implementation or evaluation.

Associated PR: PR #138 (non-draft; base split/btw-work-runtime).

Acceptance criteria

• The originating IM session or WebChat message_id receives acknowledgement, streamed output, per-model-call agent_stats, and the final result in the correct order.
• Acknowledgement does not prematurely end the WebChat request. Concurrent requests, targeted interrupts, and follow-up capture remain request-scoped.
• Reply content checks, TTS/T2I decoration, delivery, and stop-propagation remain effective; already-completed inbound stages are not rerun.
• Successful delivery, execution failure, delivery failure, and cancellation release temporary files and event registrations without early cleanup or duplicate finalization.
• Integration tests exercise the real scheduler and WebChat protocol; a mocked dispatcher success test is insufficient evidence for the complete path.

Dependencies and delivery

Blocked by: B3 / #125

Integrates with B2 / #124 before a work submission is considered usable. Preserve existing current-master request protocol tests.

Implementation anchors

Historical prototype 33ee103a62937db3e930c89ba47a648b75cc7772 provides provenance, not code to copy unchanged:

• astrbot/core/pipeline/scheduler.py: deliver_detached_result / finalize_detached_event.
• astrbot/core/agent/btw/work_loop.py: WorkLoop._run_detached.
• astrbot/core/webchat/emitter.py: WebChat completion delivery.

Integrate with the current tool catalog, Skill snapshot assembly, and authorization service, rechecking current master when implementation begins.

Validation

Commands below are required for the implementation PR, not results claimed by this issue.

Existing current-master regression baseline:

uv run pytest tests/unit/test_pipeline_scheduler_order.py tests/unit/test_webchat_run_coordinator.py tests/unit/test_webchat_service.py

Historical prototype tests to adapt with the feature (they are not shipped by documentation-only PR #28):

• tests/unit/test_btw.py

For changed documentation, run pnpm run docs:build from docs/ and make check-md from the repository root. Update OpenAPI and generated outputs together only if the HTTP contract changes.

Out of scope

A new HTTP protocol, a session-wide busy flag, or a separate response pipeline is not required.

Repository requirements

Follow AGENTS.md, GOVERNANCE.md, and AI_POLICY.md. This issue uses the feature_request template. Keep Python 3.14+, current configuration shapes, existing authorization boundaries, and bilingual feature documentation. A follow-up PR requires human maintainer review and a separate AI-assisted review. Use the feat PR template for the corresponding work.

Author

Agent

Agent note

Codex prepared this development issue at the user's request from PR #28, its discussion, the referenced source, existing tests, and current-master integration points. AI assisted the research and English drafting. Filing this issue changes no runtime behavior and does not claim feature tests or model trials have passed. Remaining decisions concern implementation details and experimental evidence within the stated scope.