fix(tui): proactive mouse disable on ConPTY + /mouse toggle command

On Windows WSL2, ConPTY implicitly enables mouse event injection when
the alternate screen buffer (DEC 1049) is entered, causing raw escape
sequences to appear in the transcript as ghost characters.

Fix (two parts):
1. ConPTY fix: send DISABLE_MOUSE_TRACKING immediately after entering
   alt screen when mouse tracking is off (AlternateScreen.tsx)
2. Runtime toggle: add /mouse [on|off|toggle] slash command with config
   persistence (display.tui_mouse) so users can manage this at runtime

The env var HERMES_TUI_DISABLE_MOUSE continues to work as the initial
default, but can now be overridden via /mouse and persisted to config.

Closes: upstream ConPTY mouse injection issue
Credits: OutThisLife / PR #13716 for the toggle concept

tui_gateway/server.py

@@ -2789,6 +2789,23 @@ def _(rid, params: dict) -> dict:
         _write_config_key("display.tui_statusbar", nv)
         return _ok(rid, {"key": key, "value": nv})
 
+    if key == "mouse":
+        raw = str(value or "").strip().lower()
+        display = _load_cfg().get("display") if isinstance(_load_cfg().get("display"), dict) else {}
+        current = bool(display.get("tui_mouse", True))
+
+        if raw in ("", "toggle"):
+            nv = not current
+        elif raw == "on":
+            nv = True
+        elif raw == "off":
+            nv = False
+        else:
+            return _err(rid, 4002, f"unknown mouse value: {value}")
+
+        _write_config_key("display.tui_mouse", nv)
+        return _ok(rid, {"key": key, "value": "on" if nv else "off"})
+
     if key in ("prompt", "personality", "skin"):
         try:
             cfg = _load_cfg()
@@ -2917,6 +2934,10 @@ def _(rid, params: dict) -> dict:
             display.get("tui_statusbar", "top") if isinstance(display, dict) else "top"
         )
         return _ok(rid, {"value": _coerce_statusbar(raw)})
+    if key == "mouse":
+        display = _load_cfg().get("display")
+        on = display.get("tui_mouse", True) if isinstance(display, dict) else True
+        return _ok(rid, {"value": "on" if on else "off"})
     if key == "mtime":
         cfg_path = _hermes_home / "config.yaml"
         try:

ui-tui/packages/hermes-ink/src/ink/components/AlternateScreen.tsx

@@ -53,7 +53,7 @@ export function AlternateScreen(t0: Props) {
       }
 
       writeRaw(
-        ENTER_ALT_SCREEN + ERASE_SCROLLBACK + ERASE_SCREEN + CURSOR_HOME + (mouseTracking ? ENABLE_MOUSE_TRACKING : '')
+        ENTER_ALT_SCREEN + ERASE_SCROLLBACK + ERASE_SCREEN + CURSOR_HOME + (mouseTracking ? ENABLE_MOUSE_TRACKING : DISABLE_MOUSE_TRACKING)
       )
       ink?.setAltScreenActive(true, mouseTracking)
 

ui-tui/packages/hermes-ink/src/ink/ink.tsx

@@ -1121,6 +1121,23 @@ export default class Ink {
       this.repaint()
     }
   }
+
+  /**
+   * Toggle mouse tracking at runtime while the alt screen is active.
+   * Writes the appropriate DEC reset/set sequences so the terminal
+   * (and ConPTY on Windows WSL2) reflects the change immediately.
+   */
+  setAltScreenMouseTracking(enabled: boolean): void {
+    if (this.altScreenMouseTracking === enabled) {
+      return
+    }
+
+    this.altScreenMouseTracking = enabled
+
+    if (this.altScreenActive) {
+      this.options.stdout.write(enabled ? ENABLE_MOUSE_TRACKING : DISABLE_MOUSE_TRACKING)
+    }
+  }
   get isAltScreenActive(): boolean {
     return this.altScreenActive
   }

ui-tui/src/app.tsx

@@ -1,18 +1,21 @@
+import { useStore } from '@nanostores/react'
+
 import { GatewayProvider } from './app/gatewayContext.js'
 import { useMainApp } from './app/useMainApp.js'
+import { $uiState } from './app/uiStore.js'
 import { AppLayout } from './components/appLayout.js'
-import { MOUSE_TRACKING } from './config/env.js'
 import type { GatewayClient } from './gatewayClient.js'
 
 export function App({ gw }: { gw: GatewayClient }) {
   const { appActions, appComposer, appProgress, appStatus, appTranscript, gateway } = useMainApp(gw)
+  const { mouseTracking } = useStore($uiState)
 
   return (
     <GatewayProvider value={gateway}>
       <AppLayout
         actions={appActions}
         composer={appComposer}
-        mouseTracking={MOUSE_TRACKING}
+        mouseTracking={mouseTracking}
         progress={appProgress}
         status={appStatus}
         transcript={appTranscript}

ui-tui/src/app/interfaces.ts

@@ -88,6 +88,7 @@ export interface UiState {
   detailsMode: DetailsMode
   info: null | SessionInfo
   inlineDiffs: boolean
+  mouseTracking: boolean
   sections: SectionVisibility
   showCost: boolean
   showReasoning: boolean

ui-tui/src/app/slash/commands/core.ts

@@ -84,6 +84,27 @@ export const coreCommands: SlashCommand[] = [
     run: (_arg, ctx) => ctx.session.die()
   },
 
+  {
+    aliases: ['scroll'],
+    help: 'toggle mouse/wheel tracking [on|off|toggle]',
+    name: 'mouse',
+    run: (arg, ctx) => {
+      const current = ctx.ui.mouseTracking
+      const next = flagFromArg(arg, current)
+
+      if (next === null) {
+        return ctx.transcript.sys('usage: /mouse [on|off|toggle]')
+      }
+
+      patchUiState({ mouseTracking: next })
+      ctx.gateway
+        .rpc<ConfigSetResponse>('config.set', { key: 'mouse', value: next ? 'on' : 'off' })
+        .catch(() => {})
+
+      queueMicrotask(() => ctx.transcript.sys(`mouse tracking ${next ? 'on' : 'off'}`))
+    }
+  },
+
   {
     aliases: ['new'],
     help: 'start a new session',

ui-tui/src/app/uiStore.ts

@@ -2,6 +2,7 @@ import { atom } from 'nanostores'
 
 import { ZERO } from '../domain/usage.js'
 import { DEFAULT_THEME } from '../theme.js'
+import { MOUSE_TRACKING } from '../config/env.js'
 
 import type { UiState } from './interfaces.js'
 
@@ -12,6 +13,7 @@ const buildUiState = (): UiState => ({
   detailsMode: 'collapsed',
   info: null,
   inlineDiffs: true,
+  mouseTracking: MOUSE_TRACKING,
   sections: {},
   showCost: false,
   showReasoning: false,

ui-tui/src/app/useConfigSync.ts

@@ -46,6 +46,7 @@ export const applyDisplay = (cfg: ConfigFullResponse | null, setBell: (v: boolea
     compact: !!d.tui_compact,
     detailsMode: resolveDetailsMode(d),
     inlineDiffs: d.inline_diffs !== false,
+    mouseTracking: d.tui_mouse !== false,
     sections: resolveSections(d.sections),
     showCost: !!d.show_cost,
     showReasoning: !!d.show_reasoning,

ui-tui/src/gatewayTypes.ts

@@ -61,6 +61,7 @@ export interface ConfigDisplayConfig {
   streaming?: boolean
   thinking_mode?: string
   tui_compact?: boolean
+  tui_mouse?: boolean
   tui_statusbar?: 'bottom' | 'off' | 'on' | 'top' | boolean
 }