refactor(tasks): extract headless task runner

[ewen-poch]

Problem

Task automation orchestration lived in the public Web transport adapter. That coupled HTTP compatibility, ACP/session lifecycle, artifacts, previews, and runtime-event handling in one module, making ownership unclear and the adapter difficult to change safely.

Proposed change

Extract a headless TaskRunner that owns task run and artifact orchestration behind narrow project, session, agent, artifact, preview, and event ports. Keep task-api.ts as a compatibility adapter for the existing public HTTP surface.

flowchart LR
  HTTP["HTTP routes"] --> Adapter["Task HTTP compatibility adapter"]
  Adapter --> Runner["TaskRunner"]
  Events["F3 runtime events"] --> Runner
  Runner --> Ports["Narrow capability ports"]
  Ports --> Facade["Temporary IPC / WebRPC facade"]
  Runner --> PublicEvents["Existing public task-event projection"]

Loading

The temporary facade remains an explicit A6/T2 removal target; the new task module does not depend on IPC registries, routers, channel names, or generic invoke contracts.

Scope and compatibility

• Preserve existing routes, request/response bodies, status codes, task events, CLI behavior, SDK behavior, and persisted schemas.
• Preserve controller-scoped lifecycle and the current SDK/CLI wait timeout; do not add a task-internal timeout.
• Preserve Electron/Web/CLI IPC compatibility and the existing Specialist, Permission, and Compute capability asymmetry.
• Keep Issue [Feature]: Provider-neutral multi-agent research orchestration #458 forward-compatible without adding orchestration state or public APIs.
• No data-model, data-relation, or user-interaction changes.

Acceptance and verification

• TaskRunner and adapter tests: 20 passed.
• SDK/CLI compatibility tests: 16 passed.
• HTTP compatibility tests: 15 passed.
• F3/controller lifecycle tests: 12 passed.
• Architecture search: no IPC router/registry imports, channel strings, or generic invoke dependencies in the task module.
• npm run typecheck: passed.
• npm run lint: 0 errors; 23 pre-existing warnings.
• npm test: 642 files passed, 15 skipped; 9,456 tests passed, 184 skipped.

Review

Independent Standards and Spec reviews found no remaining actionable issues after adding adapter-mapping certification and the explicit A6/T2 removal note. CI and platform E2E remain the final merge gate. Merge by squash after all required checks pass.

[github-actions]

Codex Review

Verdict: mergeable

No actionable findings.

Summary: Static inspection found no concrete merge-blocking defects in the requested changes.