tui_gateway/ + tui-ui/ — the TUI and its JSON-RPC backend

Applies on top of the root AGENTS.md. The TUI fully replaces the classic prompt_toolkit CLI; activate with loki --tui or LOKI_TUI=1. tui_gateway is ALSO the backend the Desktop app and the dashboard /chat talk to — changes here have three consumers.

Process model

loki --tui
  └─ Node (Ink)  ──stdio JSON-RPC──  Python (tui_gateway)
       │                                  └─ AIAgent + tools + sessions
       └─ renders transcript, composer, prompts, activity

TypeScript owns the screen. Python owns sessions, tools, model calls, and slash-command logic. Never move agent behaviour into the renderer.

Transport

Newline-delimited JSON-RPC over stdio: requests from Ink, events from Python. tui_gateway/server.py is the facade with the method/event catalog; methods live in methods_*.py siblings (methods_config, methods_complete, methods_browser, methods_bot_relay, ...), event publishing in event_publisher.py / event_replay.py. Desktop reaches the same server over WebSocket via apps/shared (JsonRpcGatewayClient). New RPC = a new methods_<topic>.py or an entry in an existing topical sibling, registered in the table — no if method == ... chain (root shape rules).

Key surfaces

Shared subagent snapshots

subagent.list({session_id}) returns {subagents, delegations} for the calling transport's live session. Live child records are pinned to the exact session record and transport. Child authority is resolved at RPC time against the owning session's LIVE transport slot, so every authenticated reattach path (prompt.submit, queued drain, resume, activate, viewer failover) carries it with no registry bookkeeping — never add a per-record transport sync at an attach site; foreign or retired generations remain inaccessible. last_tool is the last started tool, not an in-flight indicator. Async completion units are not agents and lack exact generation authority; delegations remains an empty array for wire compatibility. No dispatch context, results, callbacks, or routing keys are sent. Clients hydrate from this snapshot on their existing poll and avoid updates when unchanged.

subagent.tail({session_id, subagent_id}) returns {subagent_id, available, text, truncated}: the last 16 KiB of the live child's existing transcript. Poll only the selected detail. Missing/finished/foreign children return an unavailable empty snapshot; no client-supplied path is opened. This is live-only, not persisted completion history. Invalid session/transport returns error 4001. subagent.steer({session_id, subagent_id, text}) remains the shared control: status: queued acknowledges acceptance, not delivery; final boundary races are reported by the existing runtime as missed_steer. subagent.interrupt({session_id, subagent_id}) requires the same exact live session/transport/generation ownership, including for subtree members. Missing RPC session authority is rejected; direct in-process interrupt_subagent(id) retains its legacy unscoped contract.

Slash command flow

1. Built-in client commands (/help, /quit, /clear, /resume, /copy, /paste, ...) are handled locally in app.tsx.
2. Everything else → slash.exec, which runs in the persistent _SlashWorker subprocess → command.dispatch fallback, which the gateway resolves into a skill / alias / exec directive (a skill command resolves to {type: "skill", message} and is submitted as a normal prompt).

commands.catalog (empty-query list) and complete.slash (typed-query completions) already include built-ins, user quick_commands, AND skill-derived commands (scan_skill_commands() / get_skill_commands()) — clients do not need a new RPC to see skills. The command definitions themselves come from loki_cli/commands.py (loki_cli/AGENTS.md).

Dev commands

cd tui-ui
npm install       # first time
npm run dev       # watch mode (rebuilds loki-ink + tsx --watch)
npm start         # production
npm run build     # full build (loki-ink + tsc)
npm run typecheck # tsc --noEmit
npm run lint      # eslint
npm run fmt       # prettier
npm test          # vitest

Python tests: tests/tui_gateway/ via scripts/run_tests.sh. TS tests: vitest in tui-ui. A Python test that asserts about package.json / .ts sources will not run on a JS-only PR — keep JS-side assertions in vitest (root testing rules). Root TypeScript style rules apply.

Related: web/AGENTS.md (dashboard embeds this TUI over a PTY), apps/desktop/AGENTS.md (own renderer on the same backend).