fix(tui): make /clear confirm window humane (3s → 30s, reset on other slash)

The 3s gate was too tight — users reading the prompt and retyping
consistently blow past it and get stuck in a loop ("press /clear
again within 3s" forever). Fixes:

- bump CONFIRM_WINDOW_MS 3_000 → 30_000
- drop the time number from the confirmation message to remove the
  pressure vibe: "press /clear again to confirm — starts a new session"
- reset the gate from createSlashHandler whenever any non-destructive
  slash command runs, so stale arming from 20s ago can't silently
  turn the next /clear into an unintended confirm
- export the gate + isDestructiveCommand helper for that wiring
- add armed() introspection method

Follow-up to #4069 / 3366714b.

ui-tui/src/__tests__/destructive.test.ts

@@ -3,6 +3,10 @@ import { describe, expect, it } from 'vitest'
 import { CONFIRM_WINDOW_MS, createDestructiveGate } from '../domain/destructive.js'
 
 describe('createDestructiveGate', () => {
+  it('uses a generous default window so real humans can retype (#4069)', () => {
+    expect(CONFIRM_WINDOW_MS).toBeGreaterThanOrEqual(15_000)
+  })
+
   it('first request is not confirmed — it arms the gate', () => {
     const g = createDestructiveGate()
     expect(g.request('clear', 0)).toBe(false)
@@ -11,7 +15,7 @@ describe('createDestructiveGate', () => {
   it('second request within window with same key is confirmed', () => {
     const g = createDestructiveGate()
     g.request('clear', 0)
-    expect(g.request('clear', 2_500)).toBe(true)
+    expect(g.request('clear', CONFIRM_WINDOW_MS - 1)).toBe(true)
   })
 
   it('second request outside the window re-arms and is not confirmed', () => {
@@ -20,6 +24,15 @@ describe('createDestructiveGate', () => {
     expect(g.request('clear', CONFIRM_WINDOW_MS + 1)).toBe(false)
   })
 
+  it('armed() reports the pending key while fresh, null otherwise', () => {
+    const g = createDestructiveGate(100)
+    expect(g.armed()).toBe(null)
+    g.request('clear')
+    expect(g.armed()).toBe('clear')
+    g.reset()
+    expect(g.armed()).toBe(null)
+  })
+
   it('different key re-arms the gate, does not confirm', () => {
     const g = createDestructiveGate()
     g.request('clear', 0)

ui-tui/src/app/createSlashHandler.ts

@@ -3,6 +3,7 @@ import type { SlashExecResponse } from '../gatewayTypes.js'
 import { asCommandDispatch, rpcErrorMessage } from '../lib/rpc.js'
 
 import type { SlashHandlerContext } from './interfaces.js'
+import { destructiveGate, isDestructiveCommand } from './slash/commands/core.js'
 import { findSlashCommand } from './slash/registry.js'
 import type { SlashRunCtx } from './slash/types.js'
 import { getUiState } from './uiStore.js'
@@ -40,11 +41,17 @@ export function createSlashHandler(ctx: SlashHandlerContext): (cmd: string) => b
     const found = findSlashCommand(parsed.name)
 
     if (found) {
+      if (!isDestructiveCommand(found.name)) {
+        destructiveGate.reset()
+      }
+
       found.run(parsed.arg, runCtx, cmd)
 
       return true
     }
 
+    destructiveGate.reset()
+
     if (catalog?.canon) {
       const needle = `/${parsed.name}`.toLowerCase()
 

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

@@ -15,7 +15,11 @@ import { patchOverlayState } from '../../overlayStore.js'
 import { patchUiState } from '../../uiStore.js'
 import type { SlashCommand } from '../types.js'
 
-const destructiveGate = createDestructiveGate()
+export const destructiveGate = createDestructiveGate()
+
+const DESTRUCTIVE_COMMANDS = new Set(['clear', 'new'])
+
+export const isDestructiveCommand = (name: string) => DESTRUCTIVE_COMMANDS.has(name)
 
 const flagFromArg = (arg: string, current: boolean): boolean | null => {
   if (!arg) {
@@ -89,7 +93,7 @@ export const coreCommands: SlashCommand[] = [
       const label = cmd.startsWith('/new') ? '/new' : '/clear'
 
       if (!NO_CONFIRM_DESTRUCTIVE && !destructiveGate.request('clear')) {
-        return ctx.transcript.sys(`press ${label} again within 3s to confirm (starts a new session)`)
+        return ctx.transcript.sys(`press ${label} again to confirm — starts a new session`)
       }
 
       patchUiState({ status: 'forging session…' })

ui-tui/src/domain/destructive.ts

@@ -1,6 +1,7 @@
-export const CONFIRM_WINDOW_MS = 3_000
+export const CONFIRM_WINDOW_MS = 30_000
 
 export interface DestructiveGate {
+  armed: () => null | string
   request: (key: string, now?: number) => boolean
   reset: () => void
 }
@@ -8,9 +9,12 @@ export interface DestructiveGate {
 export const createDestructiveGate = (windowMs = CONFIRM_WINDOW_MS): DestructiveGate => {
   let pending: { at: number; key: string } | null = null
 
+  const isFresh = (now: number) => pending != null && now - pending.at < windowMs
+
   return {
+    armed: () => (pending != null && isFresh(Date.now()) ? pending.key : null),
     request: (key, now = Date.now()) => {
-      const confirmed = pending?.key === key && now - pending.at < windowMs
+      const confirmed = pending?.key === key && isFresh(now)
 
       pending = confirmed ? null : { at: now, key }