feat: slash commands + cross-session history + mode shortcuts

Slash Commands:
- Added /fix, /test, /review (coding), /ask, /agent, /plan (mode switch),
  /clear, /compact, /model (session). Total: 30 commands with categories.
- /ask, /agent, /plan switch modes locally (no gateway round-trip)
- /clear resets chat + activities

Cross-Session History:
- lib/chat-history.ts: localStorage-backed input history (50 entries max)
- ↑/↓ arrow keys recall previous inputs from any session
- HistoryNavigator class preserves current draft while browsing
- History saved on every send, deduped, most-recent-first

Mode Cycling:
- ⇧Tab hint shown next to mode selector
- Shift+Tab keyboard shortcut cycles Ask → Agent → Plan

Author: BunsDev

components/agent-panel.tsx

@@ -51,6 +51,7 @@ import {
   getEffectiveSystemPrompt,
   getAgentConfig,
 } from '@/lib/agent-session'
+import { addChatHistory, HistoryNavigator } from '@/lib/chat-history'
 import {
   SKILL_FIRST_OVERRIDE_TOKEN,
   buildSkillFirstBlockMessage,
@@ -396,6 +397,7 @@ export function AgentPanel() {
   } | null>(null)
 
   const inputRef = useRef<HTMLTextAreaElement>(null)
+  const historyNav = useRef(new HistoryNavigator())
   const sessionInitRef = useRef(false)
   const sentKeysRef = useRef(new Set<string>())
   const handledKeysRef = useRef(new Set<string>())
@@ -554,6 +556,9 @@ export function AgentPanel() {
     }
   }, [isStreaming, sending, turnStartTime])
 
+  // ─── Load chat input history ─────────────────────────────────
+  useEffect(() => { historyNav.current.load() }, [])
+
   // ─── Listen for chat events (streaming replies) ───────────────
   useEffect(() => {
     const callbacks = {
@@ -1213,6 +1218,21 @@ export function AgentPanel() {
     const text = (overrideText ?? input).trim()
     if (!text || sending) return
 
+    // Handle slash commands locally
+    if (text === '/ask') { setAgentMode('ask'); setInput(''); return }
+    if (text === '/agent') { setAgentMode('agent'); setInput(''); return }
+    if (text === '/plan') { setAgentMode('plan'); setInput(''); return }
+    if (text === '/clear') {
+      setMessages([])
+      setAgentActivities([])
+      setInput('')
+      return
+    }
+
+    // Save to cross-session history
+    addChatHistory(text)
+    historyNav.current.reset()
+
     logChatDebug('send attempt', {
       textLength: text.length,
       mode: agentMode,
@@ -1881,33 +1901,39 @@ export function AgentPanel() {
   const suggestions = useMemo(() => {
     if (!input.startsWith('/')) return []
     const cmds = [
+      // Coding
       { cmd: '/edit', desc: 'Edit current file', icon: 'lucide:pencil' },
       { cmd: '/explain', desc: 'Explain code', icon: 'lucide:book-open' },
       { cmd: '/refactor', desc: 'Refactor code', icon: 'lucide:refresh-cw' },
       { cmd: '/generate', desc: 'Generate new code', icon: 'lucide:plus' },
       { cmd: '/search', desc: 'Search across repo', icon: 'lucide:search' },
-      {
-        cmd: '/commit',
-        desc: 'Commit changes (AI if empty)',
-        icon: 'lucide:git-commit-horizontal',
-      },
+      { cmd: '/fix', desc: 'Fix errors in code', icon: 'lucide:wrench' },
+      { cmd: '/test', desc: 'Write tests for code', icon: 'lucide:flask-conical' },
+      { cmd: '/review', desc: 'Code review current changes', icon: 'lucide:scan-eye' },
+      // Git
+      { cmd: '/commit', desc: 'Commit changes (AI message)', icon: 'lucide:git-commit-horizontal' },
       { cmd: '/diff', desc: 'Show changes', icon: 'lucide:git-compare' },
-      { cmd: '/skill', desc: 'Open skill commands', icon: 'lucide:sparkles' },
-      { cmd: '/skill find', desc: 'Search for more skills', icon: 'lucide:search' },
-      { cmd: '/skill use', desc: 'Apply a bundled skill', icon: 'lucide:play' },
       { cmd: '/changes', desc: 'Pre-commit review', icon: 'lucide:eye' },
       { cmd: '/unstage', desc: 'Unstage all staged files', icon: 'lucide:minus-circle' },
       { cmd: '/undo', desc: 'Undo last commit', icon: 'lucide:undo-2' },
       { cmd: '/pull', desc: 'Pull latest changes', icon: 'lucide:arrow-down-circle' },
       { cmd: '/push', desc: 'Push to origin', icon: 'lucide:arrow-up-circle' },
       { cmd: '/sync', desc: 'Pull and push current branch', icon: 'lucide:refresh-cw' },
       { cmd: '/pr', desc: 'View pull requests', icon: 'lucide:git-pull-request' },
-      {
-        cmd: '/pr create',
-        desc: 'Create pull request',
-        icon: 'lucide:git-pull-request-create-arrow',
-      },
+      { cmd: '/pr create', desc: 'Create pull request', icon: 'lucide:git-pull-request-create-arrow' },
       { cmd: '/merge', desc: 'Merge pull request', icon: 'lucide:git-merge' },
+      // Modes
+      { cmd: '/ask', desc: 'Switch to Ask mode', icon: 'lucide:message-circle' },
+      { cmd: '/agent', desc: 'Switch to Agent mode', icon: 'lucide:bot' },
+      { cmd: '/plan', desc: 'Switch to Plan mode', icon: 'lucide:list-checks' },
+      // Session
+      { cmd: '/clear', desc: 'Clear chat history', icon: 'lucide:trash-2' },
+      { cmd: '/compact', desc: 'Compact session context', icon: 'lucide:minimize-2' },
+      { cmd: '/model', desc: 'Show or set model', icon: 'lucide:cpu' },
+      // Skills
+      { cmd: '/skill', desc: 'Open skill commands', icon: 'lucide:sparkles' },
+      { cmd: '/skill find', desc: 'Search for more skills', icon: 'lucide:search' },
+      { cmd: '/skill use', desc: 'Apply a bundled skill', icon: 'lucide:play' },
     ]
     const term = input.toLowerCase()
     return cmds.filter((c) => c.cmd.startsWith(term))
@@ -1941,6 +1967,30 @@ export function AgentPanel() {
           return
         }
       }
+      // ↑/↓: navigate input history (only when input is empty or at history position)
+      if (e.key === 'ArrowUp' && !e.shiftKey) {
+        const textarea = inputRef.current
+        if (textarea && textarea.selectionStart === 0 && textarea.selectionEnd === 0) {
+          historyNav.current.setDraft(input)
+          const prev = historyNav.current.up()
+          if (prev !== null) {
+            e.preventDefault()
+            setInput(prev)
+            return
+          }
+        }
+      }
+      if (e.key === 'ArrowDown' && !e.shiftKey) {
+        const textarea = inputRef.current
+        if (textarea && textarea.selectionStart === textarea.value.length) {
+          const next = historyNav.current.down()
+          if (next !== null) {
+            e.preventDefault()
+            setInput(next)
+            return
+          }
+        }
+      }
       // Shift+Tab: cycle agent mode (Ask → Agent → Plan → Ask)
       if (e.key === 'Tab' && e.shiftKey) {
         e.preventDefault()

components/chat/chat-input-bar.tsx

@@ -596,7 +596,10 @@ export function ChatInputBar({
 
         {/* Bottom bar — mode + model (model hidden on mobile) */}
         <div className="flex items-center justify-between mt-1">
-          <ModeSelector mode={agentMode} onChange={setAgentMode} />
+          <div className="flex items-center gap-1.5">
+            <ModeSelector mode={agentMode} onChange={setAgentMode} />
+            <span className="hidden sm:inline text-[9px] text-[var(--text-disabled)]">⇧Tab</span>
+          </div>
           <div className="hidden sm:flex items-center gap-2">
             {modelInfo.current && (
               <div className="relative">

lib/chat-history.ts

@@ -0,0 +1,78 @@
+/**
+ * Cross-session chat input history.
+ * Persists to localStorage for recall across app restarts.
+ */
+
+const STORAGE_KEY = 'code-editor:chat-history'
+const MAX_ENTRIES = 50
+
+export function getChatHistory(): string[] {
+  try {
+    const raw = localStorage.getItem(STORAGE_KEY)
+    return raw ? JSON.parse(raw) : []
+  } catch {
+    return []
+  }
+}
+
+export function addChatHistory(text: string): void {
+  const trimmed = text.trim()
+  if (!trimmed) return
+  try {
+    const history = getChatHistory()
+    // Remove duplicate if exists
+    const filtered = history.filter(h => h !== trimmed)
+    // Add to front (most recent first)
+    filtered.unshift(trimmed)
+    // Trim to max
+    if (filtered.length > MAX_ENTRIES) filtered.length = MAX_ENTRIES
+    localStorage.setItem(STORAGE_KEY, JSON.stringify(filtered))
+  } catch {}
+}
+
+export function clearChatHistory(): void {
+  try { localStorage.removeItem(STORAGE_KEY) } catch {}
+}
+
+/**
+ * Hook-friendly history navigator.
+ * Returns [current, goUp, goDown, reset].
+ */
+export class HistoryNavigator {
+  private history: string[] = []
+  private index = -1
+  private draft = ''
+
+  load() {
+    this.history = getChatHistory()
+    this.index = -1
+    this.draft = ''
+  }
+
+  setDraft(text: string) {
+    if (this.index === -1) this.draft = text
+  }
+
+  up(): string | null {
+    if (this.history.length === 0) return null
+    if (this.index < this.history.length - 1) {
+      this.index++
+      return this.history[this.index]
+    }
+    return null
+  }
+
+  down(): string | null {
+    if (this.index <= 0) {
+      this.index = -1
+      return this.draft
+    }
+    this.index--
+    return this.history[this.index]
+  }
+
+  reset() {
+    this.index = -1
+    this.draft = ''
+  }
+}