Guards four unbounded growth paths reachable at idle — the shape matches
reports of the TUI hitting V8's 2GB heap limit after ~1m of idle with 0
tokens used (Mark-Compact freed ~6MB of 2045MB → pure retention).
- `GatewayClient.logs` + `gateway.stderr` events: 200-line cap is bytes-
uncapped; a chatty Python child emitting multi-MB lines (traceback,
dumped config, unsplit JSON) retains everything. Truncate at 4KB/line.
- `GatewayClient.bufferedEvents`: unbounded until `drain()` fires. Cap
at 2000 so a pre-mount event storm can't pin memory indefinitely.
- `useMainApp` gateway `exit` handler: didn't reset `turnController`, so
a mid-stream crash left `bufRef`/`reasoningText` alive forever.
- `pasteSnips` count-capped (32) but byte-uncapped. Add a 4MB total cap
and clear snips in `clearIn` so submitted pastes don't linger.
- `StylePool.transitionCache`: uncapped `Map<number,string>`. Full-clear
at 32k entries (mirrors `charCache` pattern).
Hoist turn state from a 286-line hook into $turnState atom + turnController
singleton. createGatewayEventHandler becomes a typed dispatch over the
controller; its ctx shrinks from 30 fields to 5. Event-handler refs and 16
threaded actions are gone.
Fold three createSlash*Handler factories into a data-driven SlashCommand[]
registry under slash/commands/{core,session,ops}.ts. Aliases are data;
findSlashCommand does name+alias lookup. Shared guarded/guardedErr combinator
in slash/guarded.ts.
Split constants.ts + app/helpers.ts into config/ (timing/limits/env),
content/ (faces/placeholders/hotkeys/verbs/charms/fortunes), domain/ (roles/
details/messages/paths/slash/viewport/usage), protocol/ (interpolation/paste).
Type every RPC response in gatewayTypes.ts (26 new interfaces); drop all
`(r: any)` across slash + main app.
Shrink useMainApp from 1216 -> 646 lines by extracting useSessionLifecycle,
useSubmission, useConfigSync. Add <Fg> themed primitive and strip ~50
`as any` color casts.
Tests: 50 passing. Build + type-check clean.
