[cyruszhang]

Summary

Allow a trusted PawApp backend to submit an analysis, reconnect after a lost response, and recover the original run instead of starting it twice. Add durable submission and command receipts, replayable events, and explicit interrupted-run recovery without automatic re-execution.

• Support independent runs and subsequent turns in an owned session, with idempotent answer/cancel commands and capability discovery.
• Load task-scoped Host tools and skills through an ephemeral capability bridge.
• Register artifacts with media type, size, and SHA-256 digest; verify ownership and content on handoff. Add explicit analysis progress and deliverable presentation metadata.
• Document the protocol, deployment limits, and integration boundary.

Based on merged #81 (14535e3). The diff contains only the remaining Engine integration: 29 files in host-core, its tests, and documentation. Model inheritance, native console support, dataset selection, scoped session ownership, Windows artifact-path fixes, and dependency updates are inherited from main.

Verification

• uv sync --locked --all-packages — passed.
• uv run --locked pytest -q — 1,094 passed, 8 skipped.
• uvx --from ruff==0.12.12 ruff check packages scripts examples tests --select E9,F63,F7,F811,F82,F841 — passed.
• uv run --locked python -m compileall -q -x '(\.venv|node_modules|__pycache__)' packages scripts examples — passed.
• git diff --check — passed.
• Tests cover duplicate submissions, transaction rollback, restart recovery, command reconciliation, namespace isolation, Host capabilities, artifact verification, and native console compatibility.
• Frontend code and dependencies are unchanged; frontend checks were not rerun locally.

Risk and compatibility

• Durable submissions require SQL storage; JSON mode explicitly reports unsupported. SQLite is tested; PostgreSQL recovery needs separate validation.

• Adds submission and command receipt tables. Run one Engine process/worker per database; execution tracking and live event delivery remain process-local.

• The Engine trusts the backend's identity header. The Host must derive it from authenticated user/workspace/app context and keep service credentials out of the browser.

• Existing native console endpoints remain available. Host-side delegation, grant UI, and Main Agent continuation require their separate platform implementation.

• Package versions remain at the 0.3.2 base; this PR does not publish a release.

• No credentials, private URLs, business data, or internal-only identifiers

• Documentation and CHANGELOG.md updated

• Commit includes DCO sign-off (Signed-off-by)