git:20261003.a873b78 to git:20261003.9b16792

### Terminal Workbench / TUI (`packages/harness/deerflow/tui/`)

A terminal-native UI over the embedded harness, exposed as the `deerflow` console script (`[project.scripts]` in `packages/harness/pyproject.toml`). It is a UI shell over `DeerFlowClient` and does **not** fork agent behavior. `textual` is an optional dependency (`deerflow-harness[tui]`; also in the backend dev group); the console script degrades to headless help when it is absent. Full guide: [docs/TUI.md](../../../../docs/TUI.md).

**Module layout** (all layers except `app.py` and `widgets/` are pure / Textual-free and unit-tested directly):

- `cli.py` — `plan_launch()` (pure launch-mode decision) + headless `--print` / `--json` + `main()` entry point. Headless modes exit `1` when the final AI message carries `deerflow_error_fallback` (provider failures arrive as flagged messages, not exceptions). `_RunOutcome` and `chat()` share `_AIMessageAccumulator`: deltas accumulate per message id and the last content-bearing AI id supplies the text; metadata-only events preserve that id. Fallback writers must supply text or flag an id whose text was already emitted. Keep the client import lazy so help and launch planning do not load the agent graph. TTY → TUI, else headless help. `--tui-transparent` / `DEER_FLOW_TUI_TRANSPARENT` opt into terminal-default backgrounds without changing the solid-theme default. Uses an **absolute** `from deerflow.tui.app import run_tui` so the `app.py` module name doesn't trip `test_harness_boundary.py` (which records relative import module names verbatim).

- `view_state.py` — `ViewState` + `reduce(state, action)`, the testable heart. Rows: user / assistant / tool / system. Title captured from `values` events.

- `runtime.py` — `translate(StreamEvent) -> [Action]` (pure) + `stream_actions()` which brackets a run with `RunStarted`/`RunEnded` and turns model errors into an `AssistantError` row.

- `message_format.py` / `command_registry.py` / `input_history.py` / `render.py` / `theme.py` — pure helpers (tool summaries, slash registry + `resolve()`, ↑/↓ history, Rich renderers). The command registry must exclude every shared `RESERVED_SLASH_SKILL_NAMES` entry that the agent runtime rejects from both its picker and resolver; the `context` skill is the exception for ordinary task text, while the exact composer-only `/context compact` alias remains unavailable as a skill activation.

- `app.py` — Textual `App`. Runs `DeerFlowClient.stream()` (sync) on a worker thread and marshals actions to the UI thread via `call_from_thread`. Slash palette with `/goal` management + model/thread modal pickers; routes idle display-only `/clear` through `ClearRows` without replacing the active thread, and blocks state-resetting local commands like `/new` and `/clear` with the standard "Still working" message during an active run; priority key bindings gated by `check_action` so they never steal keys from overlays or the composer. Application-level PageUp/PageDown bindings scroll the transcript while preserving composer focus; streaming follows output only while the transcript remains at the bottom.

- `widgets/composer.py` — the composer, a Textual `TextArea`: bracketed multiline pastes retain their line breaks and indentation, `Enter` submits the whole document unchanged (only an all-whitespace document counts as empty), and Up/Down move inside it before falling back to input history at the first/last visual row (soft-wrapped rows count, so a long wrapped prompt is navigable).

- `session.py` / `persistence.py` — builds the client + checkpointer and the `ThreadMetaWriter`.

**Web UI visibility**: the Web UI lists threads from the `threads_meta` SQL table (user-scoped), not the checkpointer. `persistence.py` writes a `threads_meta` row under the default user (`"default"`) into the same DB the Gateway reads — via the harness-only `deerflow.persistence.engine.init_engine_from_config()` — so TUI sessions appear in the Web UI sidebar **without** running the Gateway. Best-effort: a no-op on the `memory` backend. All DB work runs on one long-lived background event loop (a SQLAlchemy async engine is bound to its creating loop).

**Tests**: `tests/test_tui_*.py` — pure layers via plain pytest, the app/palette/overlays via Textual's pilot harness with a fake in-process session, and `test_tui_persistence.py` for the `threads_meta` round-trip.