diff --git a/cljnim.nimble b/cljnim.nimble
index ffef1bf..e7c5700 100644
--- a/cljnim.nimble
+++ b/cljnim.nimble
@@ -8,3 +8,4 @@ bin           = @["cljnim"]
 
 # Dependencies
 requires "nim >= 2.0.0"
+requires "illwill >= 0.4.0"
diff --git a/src/cljnim.nim b/src/cljnim.nim
index 3976ed2..ccee022 100644
--- a/src/cljnim.nim
+++ b/src/cljnim.nim
@@ -1,6 +1,6 @@
 # Clojure/Nim — AI-First Clojure Compiler
 import os, osproc, strutils, times
-import reader, emitter, types, repl, macros, deps, ai_assist
+import reader, emitter, types, repl, macros, deps, ai_assist, tui
 
 proc getLibPath(): string =
   let appDir = getAppDir()
@@ -206,6 +206,7 @@ proc main() =
     echo "  cljnim deps                              Resolve dependencies from deps.edn"
     echo "  cljnim -e '<code>'                       Evaluate expression"
     echo "  cljnim ai '<description>'                Generate Clojure code with AI"
+    echo "  cljnim tui                               Start interactive TUI"
     echo ""
     echo "REPL Commands:"
     echo "  :quit, :q       Exit REPL"
@@ -346,6 +347,9 @@ proc main() =
       stderr.writeLine(aiRes.suggestion)
       quit(1)
 
+  of "tui":
+    runTui()
+
   else:
     stderr.writeLine("Unknown command: " & cmd)
     quit(1)
diff --git a/src/tui.nim b/src/tui.nim
new file mode 100644
index 0000000..2774ae8
--- /dev/null
+++ b/src/tui.nim
@@ -0,0 +1,120 @@
+# Clojure/Nim TUI — Terminal User Interface
+# Fullscreen menu-driven interface for cljnim
+
+import std/os
+import illwill
+import tui_config, tui_screens, repl
+
+proc runTui*() =
+  ## Main TUI entry point
+  let cfg = loadConfig()
+  var state = initState(cfg)
+
+  # ── illwill init ────────────────────────────────────────────────
+  proc exitProc() {.noconv.} =
+    illwillDeinit()
+    showCursor()
+    quit(0)
+
+  illwillInit(fullscreen = true)
+  setControlCHook(exitProc)
+  hideCursor()
+
+  var tb = newTerminalBuffer(terminalWidth(), terminalHeight())
+
+  # ── main loop ───────────────────────────────────────────────────
+  while not state.quit:
+    let w = terminalWidth()
+    let h = terminalHeight()
+
+    # Resize buffer if terminal changed
+    if tb.width != w or tb.height != h:
+      tb = newTerminalBuffer(w, h)
+
+    # Clear
+    tb.clear()
+    tb.setForegroundColor(fgWhite)
+
+    # Draw current screen
+    case state.currentScreen
+    of stMainMenu:
+      drawMainMenu(tb, state)
+    of stAiSettings:
+      drawAiSettings(tb, state)
+    of stCompile:
+      drawCompile(tb, state)
+    of stRun:
+      drawRun(tb, state)
+    of stAiGenerate:
+      drawAiGenerate(tb, state)
+    of stHelp:
+      drawHelp(tb, state)
+    of stRepl:
+      drawRepl(tb, state)
+
+    # Draw popup on top if active
+    drawPopup(tb, state)
+
+    # Render
+    tb.display()
+
+    # Handle input
+    var key = getKey()
+    if key == Key.None:
+      sleep(20)
+      continue
+
+    # Special handling for REPL launch
+    if state.currentScreen == stRepl and state.popupActive and state.popupMsg == "LAUNCH_REPL":
+      state.popupActive = false
+      state.popupMsg = ""
+      # Suspend TUI and launch REPL
+      illwillDeinit()
+      showCursor()
+      echo ""
+      echo "=== Starting Clojure/Nim REPL ==="
+      echo "Type :quit to return to TUI"
+      echo ""
+      var replState = initReplState(rmHuman)
+      try:
+        runHumanRepl(replState)
+      finally:
+        replState.cleanup()
+      # Re-init TUI
+      illwillInit(fullscreen = true)
+      setControlCHook(exitProc)
+      hideCursor()
+      tb = newTerminalBuffer(terminalWidth(), terminalHeight())
+      state.currentScreen = stMainMenu
+      continue
+
+    # Route input to current screen handler
+    if state.popupActive:
+      # Popup consumes Enter/Escape
+      case key
+      of Key.Enter, Key.Escape:
+        state.popupActive = false
+        state.popupMsg = ""
+      else: discard
+    else:
+      case state.currentScreen
+      of stMainMenu:
+        handleMainMenu(key, state)
+      of stAiSettings:
+        handleAiSettings(key, state)
+      of stCompile:
+        handleCompile(key, state)
+      of stRun:
+        handleRun(key, state)
+      of stAiGenerate:
+        handleAiGenerate(key, state)
+      of stHelp:
+        handleHelp(key, state)
+      of stRepl:
+        handleRepl(key, state)
+
+    sleep(20)
+
+  # ── cleanup ─────────────────────────────────────────────────────
+  illwillDeinit()
+  showCursor()
diff --git a/src/tui_config.nim b/src/tui_config.nim
new file mode 100644
index 0000000..ff316cb
--- /dev/null
+++ b/src/tui_config.nim
@@ -0,0 +1,109 @@
+# TUI Configuration Manager
+# Handles persistent config in ~/.config/cljnim/config.json
+
+import std/[json, os, strutils]
+import ai_assist
+
+type
+  TuiConfig* = object
+    provider*: string      # "deepseek", "openai", "mimo", "custom"
+    model*: string
+    baseUrl*: string
+    apiKey*: string
+    timeoutMs*: int
+    lastFile*: string      # last used .clj file
+
+const
+  DefaultProviders = {
+    "deepseek": ("https://api.deepseek.com", "deepseek-chat"),
+    "openai": ("https://api.openai.com", "gpt-4o-mini"),
+    "mimo": ("https://api.mi-mo.ai", "mimo-chat"),
+    "custom": ("", "")
+  }
+
+proc configDir(): string =
+  getHomeDir() / ".config" / "cljnim"
+
+proc configPath(): string =
+  configDir() / "config.json"
+
+proc defaultConfig*(): TuiConfig =
+  result.provider = "deepseek"
+  result.model = "deepseek-chat"
+  result.baseUrl = "https://api.deepseek.com"
+  result.apiKey = ""
+  result.timeoutMs = 15000
+  result.lastFile = ""
+
+proc loadConfig*(): TuiConfig =
+  let path = configPath()
+  if not fileExists(path):
+    return defaultConfig()
+  try:
+    let jsonStr = readFile(path)
+    let j = parseJson(jsonStr)
+    result.provider = j{"provider"}.getStr("deepseek")
+    result.model = j{"model"}.getStr("deepseek-chat")
+    result.baseUrl = j{"baseUrl"}.getStr("https://api.deepseek.com")
+    result.apiKey = j{"apiKey"}.getStr("")
+    result.timeoutMs = j{"timeoutMs"}.getInt(15000)
+    result.lastFile = j{"lastFile"}.getStr("")
+  except:
+    result = defaultConfig()
+
+proc saveConfig*(cfg: TuiConfig) =
+  let dir = configDir()
+  if not dirExists(dir):
+    createDir(dir)
+  let j = %*{
+    "provider": cfg.provider,
+    "model": cfg.model,
+    "baseUrl": cfg.baseUrl,
+    "apiKey": cfg.apiKey,
+    "timeoutMs": cfg.timeoutMs,
+    "lastFile": cfg.lastFile
+  }
+  writeFile(configPath(), pretty(j))
+
+proc toAiConfig*(cfg: TuiConfig): AiConfig =
+  ## Convert TUI config to AiConfig for ai_assist module
+  result.apiKey = cfg.apiKey
+  result.baseUrl = cfg.baseUrl
+  result.model = cfg.model
+  result.timeoutMs = cfg.timeoutMs
+  if cfg.provider == "deepseek":
+    result.provider = aiDeepSeek
+  else:
+    result.provider = aiOpenAiCompatible
+
+proc fromAiConfig*(cfg: AiConfig): TuiConfig =
+  ## Convert AiConfig to TUI config
+  result.apiKey = cfg.apiKey
+  result.baseUrl = cfg.baseUrl
+  result.model = cfg.model
+  result.timeoutMs = cfg.timeoutMs
+  if cfg.provider == aiDeepSeek:
+    result.provider = "deepseek"
+  else:
+    result.provider = "openai"
+
+proc isValid*(cfg: TuiConfig): bool =
+  cfg.apiKey.len > 0 and cfg.baseUrl.len > 0 and cfg.model.len > 0
+
+proc providerDefaults*(provider: string): tuple[baseUrl, model: string] =
+  for i in 0..<DefaultProviders.len:
+    if DefaultProviders[i][0] == provider:
+      return DefaultProviders[i][1]
+  return ("", "")
+
+proc cycleProvider*(current: string, direction: int): string =
+  let providers = @["deepseek", "openai", "mimo", "custom"]
+  var idx = providers.find(current)
+  if idx < 0: idx = 0
+  idx = (idx + direction + providers.len) mod providers.len
+  return providers[idx]
+
+proc maskedKey*(cfg: TuiConfig): string =
+  if cfg.apiKey.len <= 4:
+    return ""
+  return "*".repeat(cfg.apiKey.len - 4) & cfg.apiKey[^4..^1]
diff --git a/src/tui_screens.nim b/src/tui_screens.nim
new file mode 100644
index 0000000..a5b4375
--- /dev/null
+++ b/src/tui_screens.nim
@@ -0,0 +1,718 @@
+# TUI Screens for cljnim
+# All UI screens: Main Menu, AI Settings, Compile, Run, Generate, Help
+
+import std/[os, strutils, osproc]
+import illwill
+import tui_config, ai_assist
+
+type
+  ScreenType* = enum
+    stMainMenu, stAiSettings, stCompile, stRun, stAiGenerate, stHelp, stRepl
+
+  InputField* = object
+    label*: string
+    value*: string
+    cursorPos*: int
+    password*: bool
+    active*: bool
+
+  ScreenState* = object
+    currentScreen*: ScreenType
+    prevScreen*: ScreenType
+    menuIndex*: int
+    config*: TuiConfig
+    configDirty*: bool
+    fields*: seq[InputField]
+    activeField*: int
+    statusMsg*: string
+    statusColor*: ForegroundColor
+    popupMsg*: string
+    popupActive*: bool
+    outputText*: seq[string]
+    outputScroll*: int
+    quit*: bool
+
+proc initState*(cfg: TuiConfig): ScreenState =
+  result.currentScreen = stMainMenu
+  result.prevScreen = stMainMenu
+  result.menuIndex = 0
+  result.config = cfg
+  result.configDirty = false
+  result.activeField = 0
+  result.statusMsg = "Ready"
+  result.statusColor = fgGreen
+  result.popupMsg = ""
+  result.popupActive = false
+  result.outputText = @[]
+  result.outputScroll = 0
+  result.quit = false
+
+const
+  MenuItems = @[
+    "Compile .clj → .nim",
+    "Run .clj file",
+    "Start REPL",
+    "AI Code Generator",
+    "AI Settings",
+    "Help",
+    "Exit"
+  ]
+
+# ─── Helpers ─────────────────────────────────────────────────────────
+
+proc centerX(text: string, width: int): int =
+  max(0, (width - text.len) div 2)
+
+proc truncate(s: string, maxLen: int): string =
+  if s.len <= maxLen: s
+  else: s[0..<maxLen-3] & "..."
+
+proc wrapText(text: string, maxWidth: int): seq[string] =
+  result = @[]
+  for line in text.splitLines():
+    if line.len <= maxWidth:
+      result.add(line)
+    else:
+      var i = 0
+      while i < line.len:
+        let endIdx = min(i + maxWidth, line.len)
+        result.add(line[i..<endIdx])
+        i = endIdx
+
+proc drawBox(tb: var TerminalBuffer, x1, y1, x2, y2: int, title = "") =
+  tb.drawRect(x1, y1, x2, y2)
+  if title.len > 0 and title.len < (x2 - x1):
+    let tx = centerX(title, x2 - x1 - 1) + x1 + 1
+    tb.write(tx, y1, fgCyan, " ", title, " ")
+
+proc drawButton(tb: var TerminalBuffer, x, y: int, label: string, active: bool) =
+  if active:
+    tb.write(x, y, bgWhite, fgBlack, " ", label, " ", resetStyle)
+  else:
+    tb.write(x, y, fgWhite, "[", label, "]")
+
+proc drawOutputArea(tb: var TerminalBuffer, x1, y1, x2, y2: int, lines: seq[string], scroll: int) =
+  tb.drawRect(x1, y1, x2, y2)
+  let visibleHeight = y2 - y1 - 1
+  let startIdx = if scroll < 0: max(0, lines.len - visibleHeight) else: scroll
+  for i in 0..<visibleHeight:
+    let lineIdx = startIdx + i
+    if lineIdx < lines.len:
+      tb.write(x1 + 1, y1 + 1 + i, fgWhite, truncate(lines[lineIdx], x2 - x1 - 2))
+    else:
+      tb.write(x1 + 1, y1 + 1 + i, fgBlack, "~")
+
+# ─── Popup ───────────────────────────────────────────────────────────
+
+proc drawPopup*(tb: var TerminalBuffer, state: var ScreenState) =
+  if not state.popupActive or state.popupMsg.len == 0: return
+  let w = terminalWidth()
+  let h = terminalHeight()
+  let lines = state.popupMsg.wrapText(w - 8)
+  let pw = min(w - 4, 60)
+  let ph = lines.len + 4
+  let px = max(2, (w - pw) div 2)
+  let py = max(2, (h - ph) div 2)
+
+  tb.fill(px, py, px + pw, py + ph, " ")
+  tb.drawBox(px, py, px + pw, py + ph, "Message")
+  for i, line in lines:
+    tb.write(px + 2, py + 2 + i, fgWhite, truncate(line, pw - 4))
+  tb.write(px + 2, py + ph - 1, fgYellow, "Press ENTER or ESC to close")
+
+# ─── Main Menu ───────────────────────────────────────────────────────
+
+proc drawMainMenu*(tb: var TerminalBuffer, state: var ScreenState) =
+  let w = terminalWidth()
+  let h = terminalHeight()
+
+  # Header
+  let title = "Clojure/Nim TUI"
+  tb.write(centerX(title, w), 1, fgCyan, title)
+  tb.drawHorizLine(0, w - 1, 2, doubleStyle = true)
+
+  # Menu box
+  let boxW = 50
+  let boxH = MenuItems.len + 6
+  let bx = centerX("", boxW)
+  let by = max(4, (h - boxH) div 2)
+  drawBox(tb, bx, by, bx + boxW, by + boxH, "Main Menu")
+
+  for i, item in MenuItems:
+    let y = by + 2 + i
+    let arrow = if i == state.menuIndex: ">>> " else: "    "
+    let color = if i == state.menuIndex: fgYellow else: fgWhite
+    tb.write(bx + 4, y, color, arrow, item)
+
+  # Footer status
+  tb.drawHorizLine(0, w - 1, h - 2, doubleStyle = true)
+  let aiStatus = if state.config.isValid: state.config.provider & " (configured)" else: "not configured"
+  let status = "Status: " & state.statusMsg & " | AI: " & aiStatus
+  tb.write(2, h - 1, state.statusColor, truncate(status, w - 4))
+
+proc handleMainMenu*(key: Key, state: var ScreenState) =
+  case key
+  of Key.Up:
+    state.menuIndex = (state.menuIndex - 1 + MenuItems.len) mod MenuItems.len
+  of Key.Down:
+    state.menuIndex = (state.menuIndex + 1) mod MenuItems.len
+  of Key.Enter:
+    case state.menuIndex
+    of 0:
+      state.currentScreen = stCompile
+      state.fields = @[InputField(label: "File", value: state.config.lastFile, cursorPos: state.config.lastFile.len, active: true)]
+      state.activeField = 0
+      state.outputText = @[]
+    of 1:
+      state.currentScreen = stRun
+      state.fields = @[InputField(label: "File", value: state.config.lastFile, cursorPos: state.config.lastFile.len, active: true)]
+      state.activeField = 0
+      state.outputText = @[]
+    of 2: state.currentScreen = stRepl
+    of 3:
+      state.currentScreen = stAiGenerate
+      state.fields = @[InputField(label: "Description", value: "", cursorPos: 0, active: true)]
+      state.activeField = 0
+      state.outputText = @[]
+    of 4:
+      state.prevScreen = stMainMenu
+      state.currentScreen = stAiSettings
+      state.activeField = 0
+      state.fields = @[
+        InputField(label: "Provider", value: state.config.provider, cursorPos: state.config.provider.len, active: true),
+        InputField(label: "Model", value: state.config.model, cursorPos: state.config.model.len, active: false),
+        InputField(label: "Base URL", value: state.config.baseUrl, cursorPos: state.config.baseUrl.len, active: false),
+        InputField(label: "API Key", value: state.config.apiKey, cursorPos: state.config.apiKey.len, password: true, active: false),
+        InputField(label: "Timeout (ms)", value: $state.config.timeoutMs, cursorPos: ($state.config.timeoutMs).len, active: false)
+      ]
+    of 5: state.currentScreen = stHelp
+    of 6: state.quit = true
+    else: discard
+  of Key.Escape: state.quit = true
+  else: discard
+
+# ─── AI Settings ─────────────────────────────────────────────────────
+
+proc drawAiSettings*(tb: var TerminalBuffer, state: var ScreenState) =
+  let w = terminalWidth()
+  let h = terminalHeight()
+
+  tb.write(centerX("AI Configuration", w), 1, fgCyan, "AI Configuration")
+  tb.drawHorizLine(0, w - 1, 2, doubleStyle = true)
+
+  let startY = 4
+  let labelW = 14
+  for i, f in state.fields:
+    let y = startY + i * 2
+    let lblColor = if i == state.activeField: fgYellow else: fgWhite
+    tb.write(4, y, lblColor, truncate(f.label, labelW) & ":")
+
+    let valX = 4 + labelW + 2
+    let valW = min(50, w - valX - 4)
+    var display = f.value
+    if f.password:
+      display = if f.value.len > 4: "*".repeat(f.value.len - 4) & f.value[^4..^1] else: f.value
+    display = truncate(display, valW)
+
+    if i == state.activeField:
+      tb.write(valX, y, bgWhite, fgBlack, display & " ".repeat(valW - display.len), resetStyle)
+    else:
+      tb.write(valX, y, fgWhite, display)
+
+  # Provider hint
+  if state.activeField == 0:
+    let (defaultUrl, defaultModel) = providerDefaults(state.fields[0].value)
+    if defaultUrl.len > 0:
+      tb.write(4, startY + state.fields.len * 2 + 1, fgBlack, "Defaults: " & defaultUrl & " | " & defaultModel)
+
+  # Buttons
+  let btnY = h - 5
+  drawButton(tb, 4, btnY, "Save", state.activeField == state.fields.len)
+  drawButton(tb, 14, btnY, "Test", state.activeField == state.fields.len + 1)
+  drawButton(tb, 26, btnY, "Back", state.activeField == state.fields.len + 2)
+
+  # Footer
+  tb.drawHorizLine(0, w - 1, h - 2, doubleStyle = true)
+  tb.write(2, h - 1, state.statusColor, truncate(state.statusMsg, w - 4))
+
+proc handleAiSettings*(key: Key, state: var ScreenState) =
+  if state.popupActive:
+    case key
+    of Key.Enter, Key.Escape:
+      state.popupActive = false
+      state.popupMsg = ""
+    else: discard
+    return
+
+  let totalFields = state.fields.len + 3  # fields + Save + Test + Back
+
+  case key
+  of Key.Up:
+    state.activeField = (state.activeField - 1 + totalFields) mod totalFields
+  of Key.Down:
+    state.activeField = (state.activeField + 1) mod totalFields
+  of Key.Tab:
+    state.activeField = (state.activeField + 1) mod totalFields
+  of Key.Backspace:
+    if state.activeField < state.fields.len:
+      var f = addr state.fields[state.activeField]
+      if f.cursorPos > 0:
+        f.value.delete(f.cursorPos - 1 .. f.cursorPos - 1)
+        f.cursorPos.dec
+  of Key.Left:
+    if state.activeField < state.fields.len and state.fields[state.activeField].cursorPos > 0:
+      state.fields[state.activeField].cursorPos.dec
+  of Key.Right:
+    if state.activeField < state.fields.len and state.fields[state.activeField].cursorPos < state.fields[state.activeField].value.len:
+      state.fields[state.activeField].cursorPos.inc
+  of Key.Enter:
+    if state.activeField < state.fields.len:
+      state.activeField = (state.activeField + 1) mod totalFields
+    elif state.activeField == state.fields.len:  # Save
+      state.config.provider = state.fields[0].value
+      state.config.model = state.fields[1].value
+      state.config.baseUrl = state.fields[2].value
+      state.config.apiKey = state.fields[3].value
+      try:
+        state.config.timeoutMs = parseInt(state.fields[4].value)
+      except:
+        state.config.timeoutMs = 15000
+      saveConfig(state.config)
+      state.statusMsg = "Configuration saved!"
+      state.statusColor = fgGreen
+    elif state.activeField == state.fields.len + 1:  # Test
+      let testCfg = TuiConfig(
+        provider: state.fields[0].value,
+        model: state.fields[1].value,
+        baseUrl: state.fields[2].value,
+        apiKey: state.fields[3].value,
+        timeoutMs: (try: parseInt(state.fields[4].value) except: 15000),
+        lastFile: ""
+      )
+      state.statusMsg = "Testing connection..."
+      state.statusColor = fgYellow
+      let aiCfg = toAiConfig(testCfg)
+      let res = callAiApi(aiCfg, "Say 'OK' if you can read this.")
+      if res.ok:
+        state.popupMsg = "Connection successful!\nModel: " & testCfg.model & "\nResponse: " & res.suggestion
+        state.statusMsg = "Connection OK"
+        state.statusColor = fgGreen
+      else:
+        state.popupMsg = "Connection failed:\n" & res.suggestion
+        state.statusMsg = "Connection failed"
+        state.statusColor = fgRed
+      state.popupActive = true
+    else:  # Back
+      state.currentScreen = state.prevScreen
+      state.statusMsg = "Ready"
+      state.statusColor = fgGreen
+  of Key.Escape:
+    state.currentScreen = state.prevScreen
+    state.statusMsg = "Ready"
+    state.statusColor = fgGreen
+  else:
+    if state.activeField < state.fields.len:
+      let ch = char(key.ord)
+      if ch >= ' ' and ch <= '~':
+        var f = addr state.fields[state.activeField]
+        f.value.insert($ch, f.cursorPos)
+        f.cursorPos.inc
+        if state.activeField == 0:
+          let (url, model) = providerDefaults(f.value)
+          if url.len > 0:
+            state.fields[1].value = model
+            state.fields[2].value = url
+            state.fields[1].cursorPos = model.len
+            state.fields[2].cursorPos = url.len
+  for i in 0..<state.fields.len:
+    state.fields[i].active = (i == state.activeField)
+
+# ─── Compile Screen ──────────────────────────────────────────────────
+
+proc drawCompile*(tb: var TerminalBuffer, state: var ScreenState) =
+  let w = terminalWidth()
+  let h = terminalHeight()
+
+  tb.write(centerX("Compile to Nim", w), 1, fgCyan, "Compile to Nim")
+  tb.drawHorizLine(0, w - 1, 2, doubleStyle = true)
+
+  let valX = 12
+  let valW = min(50, w - valX - 4)
+  let f = state.fields[0]
+  let display = truncate(f.value, valW)
+  tb.write(4, 4, fgWhite, "File:")
+  if state.activeField == 0:
+    tb.write(valX, 4, bgWhite, fgBlack, display & " ".repeat(valW - display.len), resetStyle)
+  else:
+    tb.write(valX, 4, fgWhite, display)
+
+  # Buttons
+  let btnY = 7
+  drawButton(tb, 4, btnY, "Compile", state.activeField == 1)
+  drawButton(tb, 16, btnY, "Browse", state.activeField == 2)
+  drawButton(tb, 28, btnY, "Back", state.activeField == 3)
+
+  # Output
+  if state.outputText.len > 0:
+    drawOutputArea(tb, 2, 9, w - 2, h - 3, state.outputText, state.outputScroll)
+
+  tb.drawHorizLine(0, w - 1, h - 2, doubleStyle = true)
+  tb.write(2, h - 1, state.statusColor, truncate(state.statusMsg, w - 4))
+
+proc handleCompile*(key: Key, state: var ScreenState) =
+  if state.popupActive:
+    case key
+    of Key.Enter, Key.Escape:
+      state.popupActive = false
+      state.popupMsg = ""
+    else: discard
+    return
+
+  let totalFields = 4  # file + Compile + Browse + Back
+  case key
+  of Key.Up:
+    state.activeField = (state.activeField - 1 + totalFields) mod totalFields
+  of Key.Down:
+    state.activeField = (state.activeField + 1) mod totalFields
+  of Key.Tab:
+    state.activeField = (state.activeField + 1) mod totalFields
+  of Key.Backspace:
+    if state.activeField == 0 and state.fields[0].cursorPos > 0:
+      state.fields[0].value.delete(state.fields[0].cursorPos - 1 .. state.fields[0].cursorPos - 1)
+      state.fields[0].cursorPos.dec
+  of Key.Left:
+    if state.activeField == 0 and state.fields[0].cursorPos > 0:
+      state.fields[0].cursorPos.dec
+  of Key.Right:
+    if state.activeField == 0 and state.fields[0].cursorPos < state.fields[0].value.len:
+      state.fields[0].cursorPos.inc
+  of Key.Enter:
+    if state.activeField == 0:
+      state.activeField = 1
+    elif state.activeField == 1:  # Compile
+      let filePath = state.fields[0].value.strip()
+      if filePath.len == 0:
+        state.statusMsg = "Please enter a file path"
+        state.statusColor = fgRed
+      elif not fileExists(filePath):
+        state.statusMsg = "File not found: " & filePath
+        state.statusColor = fgRed
+      else:
+        state.config.lastFile = filePath
+        saveConfig(state.config)
+        state.statusMsg = "Compiling..."
+        state.statusColor = fgYellow
+        let appDir = getAppDir()
+        let cljnimBin = if fileExists(appDir / "cljnim"): appDir / "cljnim" else: "./cljnim"
+        let (output, exitCode) = execCmdEx(cljnimBin & " compile " & quoteShell(filePath))
+        state.outputText = output.splitLines()
+        if exitCode == 0:
+          state.statusMsg = "Compilation successful!"
+          state.statusColor = fgGreen
+        else:
+          state.statusMsg = "Compilation failed"
+          state.statusColor = fgRed
+    elif state.activeField == 2:  # Browse
+      state.statusMsg = "Browse not implemented — type path manually"
+      state.statusColor = fgYellow
+    else:  # Back
+      state.currentScreen = stMainMenu
+      state.statusMsg = "Ready"
+      state.statusColor = fgGreen
+  of Key.Escape:
+    state.currentScreen = stMainMenu
+    state.statusMsg = "Ready"
+    state.statusColor = fgGreen
+  else:
+    if state.activeField == 0:
+      let ch = char(key.ord)
+      if ch >= ' ' and ch <= '~':
+        state.fields[0].value.insert($ch, state.fields[0].cursorPos)
+        state.fields[0].cursorPos.inc
+
+# ─── Run Screen ──────────────────────────────────────────────────────
+
+proc drawRun*(tb: var TerminalBuffer, state: var ScreenState) =
+  let w = terminalWidth()
+  let h = terminalHeight()
+
+  tb.write(centerX("Run Clojure File", w), 1, fgCyan, "Run Clojure File")
+  tb.drawHorizLine(0, w - 1, 2, doubleStyle = true)
+
+  let valX = 12
+  let valW = min(50, w - valX - 4)
+  let display = truncate(state.fields[0].value, valW)
+  tb.write(4, 4, fgWhite, "File:")
+  if state.activeField == 0:
+    tb.write(valX, 4, bgWhite, fgBlack, display & " ".repeat(valW - display.len), resetStyle)
+  else:
+    tb.write(valX, 4, fgWhite, display)
+
+  let btnY = 7
+  drawButton(tb, 4, btnY, "Run", state.activeField == 1)
+  drawButton(tb, 14, btnY, "Browse", state.activeField == 2)
+  drawButton(tb, 26, btnY, "Back", state.activeField == 3)
+
+  if state.outputText.len > 0:
+    drawOutputArea(tb, 2, 9, w - 2, h - 3, state.outputText, state.outputScroll)
+
+  tb.drawHorizLine(0, w - 1, h - 2, doubleStyle = true)
+  tb.write(2, h - 1, state.statusColor, truncate(state.statusMsg, w - 4))
+
+proc handleRun*(key: Key, state: var ScreenState) =
+  if state.popupActive:
+    case key
+    of Key.Enter, Key.Escape:
+      state.popupActive = false
+      state.popupMsg = ""
+    else: discard
+    return
+
+  let totalFields = 4
+  case key
+  of Key.Up:
+    state.activeField = (state.activeField - 1 + totalFields) mod totalFields
+  of Key.Down:
+    state.activeField = (state.activeField + 1) mod totalFields
+  of Key.Tab:
+    state.activeField = (state.activeField + 1) mod totalFields
+  of Key.Backspace:
+    if state.activeField == 0 and state.fields[0].cursorPos > 0:
+      state.fields[0].value.delete(state.fields[0].cursorPos - 1 .. state.fields[0].cursorPos - 1)
+      state.fields[0].cursorPos.dec
+  of Key.Left:
+    if state.activeField == 0 and state.fields[0].cursorPos > 0:
+      state.fields[0].cursorPos.dec
+  of Key.Right:
+    if state.activeField == 0 and state.fields[0].cursorPos < state.fields[0].value.len:
+      state.fields[0].cursorPos.inc
+  of Key.Enter:
+    if state.activeField == 0:
+      state.activeField = 1
+    elif state.activeField == 1:  # Run
+      let filePath = state.fields[0].value.strip()
+      if filePath.len == 0:
+        state.statusMsg = "Please enter a file path"
+        state.statusColor = fgRed
+      elif not fileExists(filePath):
+        state.statusMsg = "File not found: " & filePath
+        state.statusColor = fgRed
+      else:
+        state.config.lastFile = filePath
+        saveConfig(state.config)
+        state.statusMsg = "Running..."
+        state.statusColor = fgYellow
+        let appDir = getAppDir()
+        let cljnimBin = if fileExists(appDir / "cljnim"): appDir / "cljnim" else: "./cljnim"
+        let (output, exitCode) = execCmdEx(cljnimBin & " run " & quoteShell(filePath))
+        state.outputText = output.splitLines()
+        if exitCode == 0:
+          state.statusMsg = "Execution successful!"
+          state.statusColor = fgGreen
+        else:
+          state.statusMsg = "Execution failed"
+          state.statusColor = fgRed
+    elif state.activeField == 2:  # Browse
+      state.statusMsg = "Browse not implemented — type path manually"
+      state.statusColor = fgYellow
+    else:  # Back
+      state.currentScreen = stMainMenu
+      state.statusMsg = "Ready"
+      state.statusColor = fgGreen
+  of Key.Escape:
+    state.currentScreen = stMainMenu
+    state.statusMsg = "Ready"
+    state.statusColor = fgGreen
+  else:
+    if state.activeField == 0:
+      let ch = char(key.ord)
+      if ch >= ' ' and ch <= '~':
+        state.fields[0].value.insert($ch, state.fields[0].cursorPos)
+        state.fields[0].cursorPos.inc
+
+# ─── AI Generate Screen ──────────────────────────────────────────────
+
+proc drawAiGenerate*(tb: var TerminalBuffer, state: var ScreenState) =
+  let w = terminalWidth()
+  let h = terminalHeight()
+
+  tb.write(centerX("AI Code Generator", w), 1, fgCyan, "AI Code Generator")
+  tb.drawHorizLine(0, w - 1, 2, doubleStyle = true)
+
+  let valX = 16
+  let valW = min(50, w - valX - 4)
+  let display = truncate(state.fields[0].value, valW)
+  tb.write(4, 4, fgWhite, "Description:")
+  if state.activeField == 0:
+    tb.write(valX, 4, bgWhite, fgBlack, display & " ".repeat(valW - display.len), resetStyle)
+  else:
+    tb.write(valX, 4, fgWhite, display)
+
+  let btnY = 7
+  drawButton(tb, 4, btnY, "Generate", state.activeField == 1)
+  drawButton(tb, 18, btnY, "Copy", state.activeField == 2)
+  drawButton(tb, 28, btnY, "Back", state.activeField == 3)
+
+  if state.outputText.len > 0:
+    drawOutputArea(tb, 2, 9, w - 2, h - 3, state.outputText, state.outputScroll)
+
+  tb.drawHorizLine(0, w - 1, h - 2, doubleStyle = true)
+  tb.write(2, h - 1, state.statusColor, truncate(state.statusMsg, w - 4))
+
+proc handleAiGenerate*(key: Key, state: var ScreenState) =
+  if state.popupActive:
+    case key
+    of Key.Enter, Key.Escape:
+      state.popupActive = false
+      state.popupMsg = ""
+    else: discard
+    return
+
+  let totalFields = 4
+  case key
+  of Key.Up:
+    state.activeField = (state.activeField - 1 + totalFields) mod totalFields
+  of Key.Down:
+    state.activeField = (state.activeField + 1) mod totalFields
+  of Key.Tab:
+    state.activeField = (state.activeField + 1) mod totalFields
+  of Key.Backspace:
+    if state.activeField == 0 and state.fields[0].cursorPos > 0:
+      state.fields[0].value.delete(state.fields[0].cursorPos - 1 .. state.fields[0].cursorPos - 1)
+      state.fields[0].cursorPos.dec
+  of Key.Left:
+    if state.activeField == 0 and state.fields[0].cursorPos > 0:
+      state.fields[0].cursorPos.dec
+  of Key.Right:
+    if state.activeField == 0 and state.fields[0].cursorPos < state.fields[0].value.len:
+      state.fields[0].cursorPos.inc
+  of Key.Enter:
+    if state.activeField == 0:
+      state.activeField = 1
+    elif state.activeField == 1:  # Generate
+      if not state.config.isValid:
+        state.statusMsg = "AI not configured — go to AI Settings"
+        state.statusColor = fgRed
+      else:
+        let desc = state.fields[0].value.strip()
+        if desc.len == 0:
+          state.statusMsg = "Please enter a description"
+          state.statusColor = fgRed
+        else:
+          state.statusMsg = "Generating..."
+          state.statusColor = fgYellow
+          let res = generateCode(desc)
+          if res.ok:
+            state.outputText = res.suggestion.splitLines()
+            state.statusMsg = "Code generated!"
+            state.statusColor = fgGreen
+          else:
+            state.outputText = @["Error:", res.suggestion]
+            state.statusMsg = "Generation failed"
+            state.statusColor = fgRed
+    elif state.activeField == 2:  # Copy
+      if state.outputText.len > 0:
+        let fullText = state.outputText.join("\n")
+        # Try to copy to clipboard via xclip/xsel
+        let (_, exitCode) = execCmdEx("echo " & quoteShell(fullText) & " | xclip -selection clipboard 2>/dev/null || echo " & quoteShell(fullText) & " | xsel --clipboard --input 2>/dev/null")
+        if exitCode == 0:
+          state.statusMsg = "Copied to clipboard!"
+          state.statusColor = fgGreen
+        else:
+          state.statusMsg = "Copy failed — install xclip or xsel"
+          state.statusColor = fgYellow
+    else:  # Back
+      state.currentScreen = stMainMenu
+      state.statusMsg = "Ready"
+      state.statusColor = fgGreen
+  of Key.Escape:
+    state.currentScreen = stMainMenu
+    state.statusMsg = "Ready"
+    state.statusColor = fgGreen
+  else:
+    if state.activeField == 0:
+      let ch = char(key.ord)
+      if ch >= ' ' and ch <= '~':
+        state.fields[0].value.insert($ch, state.fields[0].cursorPos)
+        state.fields[0].cursorPos.inc
+
+# ─── Help Screen ─────────────────────────────────────────────────────
+
+proc drawHelp*(tb: var TerminalBuffer, state: var ScreenState) =
+  let w = terminalWidth()
+  let h = terminalHeight()
+
+  tb.write(centerX("Help", w), 1, fgCyan, "Help")
+  tb.drawHorizLine(0, w - 1, 2, doubleStyle = true)
+
+  let helpText = @[
+    "Clojure/Nim TUI v0.1.0",
+    "",
+    "Navigation:",
+    "  Arrow Keys / Tab  Navigate menus and fields",
+    "  Enter             Select / Confirm",
+    "  Escape            Go back / Cancel",
+    "  Backspace         Delete character",
+    "",
+    "AI Configuration:",
+    "  Set your API key in AI Settings. Supported providers:",
+    "  - DeepSeek (deepseek-chat)",
+    "  - OpenAI / OpenRouter (gpt-4o-mini)",
+    "  - Xiaomi MiMo (mimo-chat)",
+    "  - Custom OpenAI-compatible endpoints",
+    "",
+    "Config is saved to: ~/.config/cljnim/config.json",
+    "",
+    "Press ESC to return to Main Menu"
+  ]
+
+  for i, line in helpText:
+    if 4 + i < h - 2:
+      tb.write(4, 4 + i, fgWhite, truncate(line, w - 8))
+
+  tb.drawHorizLine(0, w - 1, h - 2, doubleStyle = true)
+  tb.write(2, h - 1, fgGreen, "Press ESC to go back")
+
+proc handleHelp*(key: Key, state: var ScreenState) =
+  case key
+  of Key.Escape, Key.Enter:
+    state.currentScreen = stMainMenu
+  else: discard
+
+# ─── REPL Screen ─────────────────────────────────────────────────────
+
+proc drawRepl*(tb: var TerminalBuffer, state: var ScreenState) =
+  let w = terminalWidth()
+  let h = terminalHeight()
+
+  tb.write(centerX("REPL", w), 1, fgCyan, "REPL")
+  tb.drawHorizLine(0, w - 1, 2, doubleStyle = true)
+
+  let msg = @[
+    "The REPL runs in a separate terminal session.",
+    "",
+    "Press ENTER to start the REPL now.",
+    "Press ESC to go back to the menu.",
+    "",
+    "You can also run REPL from command line:",
+    "  ./cljnim repl          (human mode)",
+    "  ./cljnim repl --json   (AI/structured mode)",
+    "  ./cljnim repl --tcp 5555  (TCP server mode)"
+  ]
+
+  for i, line in msg:
+    if 6 + i < h - 2:
+      tb.write(4, 6 + i, fgWhite, truncate(line, w - 8))
+
+  tb.drawHorizLine(0, w - 1, h - 2, doubleStyle = true)
+  tb.write(2, h - 1, fgGreen, "ENTER = start REPL | ESC = back")
+
+proc handleRepl*(key: Key, state: var ScreenState) =
+  case key
+  of Key.Escape:
+    state.currentScreen = stMainMenu
+  of Key.Enter:
+    # Signal to main loop to suspend TUI and launch REPL
+    state.popupMsg = "LAUNCH_REPL"
+    state.popupActive = true
+  else: discard