diff --git a/apps/interfaces/tui/package.json b/apps/interfaces/tui/package.json
new file mode 100644
index 0000000..82cc819
--- /dev/null
+++ b/apps/interfaces/tui/package.json
@@ -0,0 +1,16 @@
+{
+  "name": "@zesdex/tui",
+  "version": "1.21.2",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "tui": "bun src/main.ts",
+    "build": "true"
+  },
+  "dependencies": {
+    "@zesdex/domain": "workspace:*"
+  },
+  "devDependencies": {
+    "@types/bun": "^1.2.0"
+  }
+}
diff --git a/apps/interfaces/tui/src/action.ts b/apps/interfaces/tui/src/action.ts
new file mode 100644
index 0000000..4dfe0ae
--- /dev/null
+++ b/apps/interfaces/tui/src/action.ts
@@ -0,0 +1,200 @@
+/**
+ * The `Action` — a single well-typed event in the TUI, produced by key input
+ * and applied to `AppStateRest` by the event loop. Mirrors
+ * `apps/interfaces/tui/src/action/mod.rs`.
+ *
+ * Flow: `handleKey` returns `Action[]` → the event loop calls `applyAction`
+ * for each → state is mutated in place. Every state mutation funnels through
+ * this single chokepoint.
+ */
+import * as fs from "node:fs";
+import { Roles } from "@zesdex/domain";
+import type { AppStateRest, Overlay } from "./state.ts";
+import {
+  makeChatMessage,
+  pushTranscript,
+  toastInfo,
+  markDirty,
+  EditorState,
+} from "./state.ts";
+import { gitDiffOutput } from "./git.ts";
+
+/** A single well-typed event in the TUI that mutates `AppStateRest`. */
+export type Action =
+  | { tag: "ForceQuit" }
+  | { tag: "SubmitInput"; text: string }
+  | { tag: "DeleteChar" }
+  | { tag: "DeleteCharRight" }
+  | { tag: "CursorLeft" }
+  | { tag: "CursorRight" }
+  | { tag: "HistoryUp" }
+  | { tag: "HistoryDown" }
+  | { tag: "ScrollUp" }
+  | { tag: "ScrollDown" }
+  | { tag: "OpenOverlay"; overlay: Overlay }
+  | { tag: "CloseOverlay" }
+  | { tag: "SystemNote"; kind: string; message: string }
+  | { tag: "QuitConfirm" }
+  | { tag: "Resize"; width: number; height: number }
+  | { tag: "Tick" }
+  | { tag: "LessonAccept"; name: string }
+  | { tag: "LessonReject"; name: string }
+  | { tag: "LessonDelete"; name: string }
+  | { tag: "StartOAuth"; provider: string }
+  | { tag: "OpenEditor"; path: string }
+  | { tag: "McpAdd"; name: string; command: string }
+  | { tag: "ModelList" }
+  | { tag: "AbortTurn" }
+  | { tag: "Compact" }
+  | { tag: "ShowDiff" }
+  | { tag: "DiffScroll"; amount: number };
+
+/** Apply an `Action` to `AppStateRest`. `state` is mutated in place. */
+export function applyAction(state: AppStateRest, action: Action): void {
+  switch (action.tag) {
+    case "ForceQuit":
+      state.quit = true;
+      break;
+
+    case "QuitConfirm":
+      state.misc.overlay = "quit_confirm";
+      state.dirty = true;
+      break;
+
+    case "Resize":
+      if (state.lastRenderWidth !== action.width) {
+        state.transcriptCache.dirty = true;
+        state.lastRenderWidth = action.width;
+      }
+      state.dirty = true;
+      break;
+
+    case "Tick":
+      handleTick(state);
+      break;
+
+    case "SubmitInput":
+      pushTranscript(state, makeChatMessage(Roles.User, action.text));
+      state.input.submit();
+      state.pendingSubmit = action.text;
+      state.tokenCountDirty = true;
+      state.dirty = true;
+      break;
+
+    case "DeleteChar":
+      state.input.deleteLeft();
+      state.dirty = true;
+      break;
+    case "DeleteCharRight":
+      state.input.deleteRight();
+      state.dirty = true;
+      break;
+    case "CursorLeft":
+      state.input.cursor = Math.max(0, state.input.cursor - 1);
+      state.dirty = true;
+      break;
+    case "CursorRight":
+      if (state.input.cursor < state.input.buffer.length) state.input.cursor += 1;
+      state.dirty = true;
+      break;
+    case "HistoryUp":
+      state.input.historyUp();
+      state.dirty = true;
+      break;
+    case "HistoryDown":
+      state.input.historyDown();
+      state.dirty = true;
+      break;
+
+    case "ScrollUp":
+      state.scroll.scrollUp(3);
+      state.dirty = true;
+      break;
+    case "ScrollDown":
+      state.scroll.scrollDown(3);
+      state.dirty = true;
+      break;
+
+    case "OpenOverlay":
+      state.misc.overlay = action.overlay;
+      state.dirty = true;
+      break;
+    case "CloseOverlay":
+      state.misc.overlay = "none";
+      state.dirty = true;
+      break;
+
+    case "SystemNote":
+      pushTranscript(state, makeChatMessage(Roles.System, action.message));
+      break;
+
+    case "ModelList":
+      state.misc.overlay = "model_selector";
+      state.dirty = true;
+      break;
+
+    case "OpenEditor":
+      {
+        const content = fs.existsSync(action.path)
+          ? fs.readFileSync(action.path, "utf8")
+          : "";
+        state.misc.editor = new EditorState(action.path, content);
+        state.misc.overlay = "editor";
+        state.dirty = true;
+      }
+      break;
+
+    case "LessonAccept":
+      toastInfo(state, `Lesson accepted: ${action.name}`);
+      break;
+    case "LessonReject":
+      toastInfo(state, `Lesson rejected: ${action.name}`);
+      break;
+    case "LessonDelete":
+      toastInfo(state, `Lesson deleted: ${action.name}`);
+      break;
+
+    case "StartOAuth":
+      toastInfo(state, `OAuth login started for ${action.provider}`);
+      break;
+
+    case "McpAdd":
+      toastInfo(state, `MCP server added: ${action.name} (${action.command})`);
+      break;
+
+    case "AbortTurn":
+      state.abortFlag.value = true;
+      toastInfo(state, "Aborting current turn...");
+      break;
+
+    case "Compact":
+      toastInfo(state, "Compacting conversation...");
+      break;
+
+    case "ShowDiff":
+      {
+        state.misc.diffContent = gitDiffOutput(state.workspaceRoots);
+        state.misc.diffScroll = 0;
+        state.misc.overlay = "diff";
+        state.dirty = true;
+      }
+      break;
+
+    case "DiffScroll":
+      {
+        const maxScroll = Math.max(0, state.misc.diffContent.split("\n").length - 1);
+        const newScroll = Math.max(0, state.misc.diffScroll + action.amount);
+        state.misc.diffScroll = Math.min(newScroll, maxScroll);
+        state.dirty = true;
+      }
+      break;
+  }
+}
+
+/** Periodic timer tick — drains queued events and applies streaming text. */
+function handleTick(state: AppStateRest): void {
+  // Streaming updates are applied via appendToLastTranscript by the turn
+  // driver; here we only reconcile cache validity and progress the spinner.
+  state.misc.tickCount += 1;
+  markDirty(state);
+}
diff --git a/apps/interfaces/tui/src/command.ts b/apps/interfaces/tui/src/command.ts
new file mode 100644
index 0000000..3c28a69
--- /dev/null
+++ b/apps/interfaces/tui/src/command.ts
@@ -0,0 +1,113 @@
+/**
+ * Slash-command parser that maps TUI `/foo` input lines into `Command`
+ * variants for the action dispatch system. Mirrors
+ * `apps/interfaces/tui/src/controller/command.rs`.
+ */
+
+import type { Action } from "./action.ts";
+
+/** A parsed slash command from the TUI input buffer. */
+export type Command =
+  | { tag: "Help" }
+  | { tag: "Quit" }
+  | { tag: "McpOpen" }
+  | { tag: "Clear" }
+  | { tag: "ClearConfirm" }
+  | { tag: "Login"; provider: string }
+  | { tag: "Edit"; path: string }
+  | { tag: "McpAdd"; name: string; command: string }
+  | { tag: "ModelList" }
+  | { tag: "Compact" }
+  | { tag: "TodoOpen" }
+  | { tag: "PlanOpen" }
+  | { tag: "UsageOpen" }
+  | { tag: "Diff" }
+  | { tag: "Unknown"; text: string };
+
+/** Parse a slash-prefixed input line into a `Command` value. */
+export function parseCommand(text: string): Command {
+  const trimmed = text.trim();
+  if (!trimmed.startsWith("/")) return { tag: "Unknown", text: trimmed };
+
+  const parts = trimmed.split(" ", 3);
+  const cmd = parts[0] ?? "";
+  const arg1 = parts[1] ?? "";
+  const arg2 = parts[2] ?? "";
+
+  switch (cmd) {
+    case "/help":
+      return { tag: "Help" };
+    case "/quit":
+      return { tag: "Quit" };
+    case "/clear":
+      return arg1 === "" ? { tag: "ClearConfirm" } : { tag: "Clear" };
+    case "/login":
+      return arg1 === "" ? { tag: "Login", provider: "" } : { tag: "Login", provider: arg1 };
+    case "/edit":
+      return { tag: "Edit", path: arg1 === "" ? "." : arg1 };
+    case "/mcp":
+      if (arg1 === "") return { tag: "McpOpen" };
+      if (arg1 === "add") {
+        const rest = arg2.trim();
+        const space = rest.indexOf(" ");
+        if (space !== -1) {
+          return { tag: "McpAdd", name: rest.slice(0, space), command: rest.slice(space + 1).trim() };
+        }
+        return { tag: "McpAdd", name: rest, command: "" };
+      }
+      return { tag: "Unknown", text: cmd };
+    case "/model":
+      return { tag: "ModelList" };
+    case "/compact":
+      return { tag: "Compact" };
+    case "/todo":
+      return { tag: "TodoOpen" };
+    case "/plan":
+      return { tag: "PlanOpen" };
+    case "/usage":
+      return { tag: "UsageOpen" };
+    case "/diff":
+      return { tag: "Diff" };
+    default:
+      return { tag: "Unknown", text: cmd };
+  }
+}
+
+/** Map a parsed `Command` into `Action` values for the event loop. */
+export function applyCommand(cmd: Command): Action[] {
+  switch (cmd.tag) {
+    case "Help":
+      return [{ tag: "OpenOverlay", overlay: "help" }];
+    case "Quit":
+      return [{ tag: "QuitConfirm" }];
+    case "McpOpen":
+      return [{ tag: "OpenOverlay", overlay: "mcp" }];
+    case "Clear":
+      return [{ tag: "SystemNote", kind: "clear", message: "Transcript cleared." }];
+    case "ClearConfirm":
+      return [{ tag: "OpenOverlay", overlay: "clear_confirm" }];
+    case "Login":
+      return [{ tag: "StartOAuth", provider: cmd.provider }];
+    case "Edit":
+      return [{ tag: "OpenEditor", path: cmd.path }];
+    case "McpAdd":
+      return [{ tag: "McpAdd", name: cmd.name, command: cmd.command }];
+    case "ModelList":
+      return [{ tag: "ModelList" }];
+    case "Compact":
+      return [{ tag: "Compact" }];
+    case "TodoOpen":
+      return [{ tag: "OpenOverlay", overlay: "todo" }];
+    case "PlanOpen":
+      return [{ tag: "OpenOverlay", overlay: "plan" }];
+    case "UsageOpen":
+      return [{ tag: "OpenOverlay", overlay: "usage" }];
+    case "Diff":
+      return [{ tag: "ShowDiff" }];
+    case "Unknown":
+      if (cmd.text.startsWith("/")) {
+        return [{ tag: "SystemNote", kind: "error", message: `Unknown command: ${cmd.text}` }];
+      }
+      return [{ tag: "SubmitInput", text: cmd.text }];
+  }
+}
diff --git a/apps/interfaces/tui/src/controller.ts b/apps/interfaces/tui/src/controller.ts
new file mode 100644
index 0000000..936a2f6
--- /dev/null
+++ b/apps/interfaces/tui/src/controller.ts
@@ -0,0 +1,330 @@
+/**
+ * Key event dispatcher: maps raw key events into `Action` variants, with
+ * special handling for overlays, autocomplete, and the inline editor.
+ * Mirrors `apps/interfaces/tui/src/controller/input.rs`.
+ *
+ * Flow: `handleKey` is called on each key press → returns `Action[]`.
+ */
+import { Roles } from "@zesdex/domain";
+import type { AppStateRest } from "./state.ts";
+import { AutocompleteKind, markDirty, toastInfo, overlayIsActive } from "./state.ts";
+import type { Action } from "./action.ts";
+import { applyCommand, parseCommand } from "./command.ts";
+
+/** A decoded terminal key event (normalised from raw input). */
+export interface KeyEvent {
+  code: string;
+  ctrl: boolean;
+  alt: boolean;
+  shift?: boolean;
+  /** For plain char events, the decoded character(s). */
+  value?: string;
+}
+
+/** Common key codes we normalise from raw input. */
+export const KeyCode = {
+  Enter: "Enter",
+  Backspace: "Backspace",
+  Delete: "Delete",
+  Left: "ArrowLeft",
+  Right: "ArrowRight",
+  Up: "ArrowUp",
+  Down: "ArrowDown",
+  PageUp: "PageUp",
+  PageDown: "PageDown",
+  Esc: "Escape",
+  Tab: "Tab",
+  Char: "Char",
+} as const;
+
+/** Normalise a raw string key (from raw-mode stdin) into a `KeyEvent`. */
+export function decodeKey(raw: string): KeyEvent | null {
+  if (raw === "\r" || raw === "\n") return { code: KeyCode.Enter, ctrl: false, alt: false };
+  if (raw === "\u001b") return { code: KeyCode.Esc, ctrl: false, alt: false };
+  if (raw === "\t") return { code: KeyCode.Tab, ctrl: false, alt: false };
+  if (raw === "\u007f" || raw === "\b") return { code: KeyCode.Backspace, ctrl: false, alt: false };
+
+  // Ctrl+letter (0x01–0x1a)
+  const ch = raw.charCodeAt(0);
+  if (ch >= 0x01 && ch <= 0x1a && raw.length === 1) {
+    const letter = String.fromCharCode(ch + 0x60);
+    return { code: KeyCode.Char, value: letter, ctrl: true, alt: false };
+  }
+
+  // ESC-prefixed sequences: arrows, page keys, alt+char.
+  if (raw.startsWith("\u001b[")) {
+    switch (raw) {
+      case "\u001b[A":
+        return { code: KeyCode.Up, ctrl: false, alt: false };
+      case "\u001b[B":
+        return { code: KeyCode.Down, ctrl: false, alt: false };
+      case "\u001b[C":
+        return { code: KeyCode.Right, ctrl: false, alt: false };
+      case "\u001b[D":
+        return { code: KeyCode.Left, ctrl: false, alt: false };
+      case "\u001b[5~":
+        return { code: KeyCode.PageUp, ctrl: false, alt: false };
+      case "\u001b[6~":
+        return { code: KeyCode.PageDown, ctrl: false, alt: false };
+      case "\u001b[3~":
+        return { code: KeyCode.Delete, ctrl: false, alt: false };
+      case "\u001b[1;5A":
+        return { code: KeyCode.Up, ctrl: true, alt: false };
+      case "\u001b[1;5B":
+        return { code: KeyCode.Down, ctrl: true, alt: false };
+      default:
+        return null;
+    }
+  }
+  if (raw.startsWith("\u001b") && raw.length > 1) {
+    // Alt+<char>
+    const inner = raw.slice(1);
+    if (inner.length === 1) {
+      return { code: KeyCode.Char, value: inner, ctrl: false, alt: true };
+    }
+    return null;
+  }
+
+  // Plain printable char(s)
+  return { code: KeyCode.Char, value: raw, ctrl: false, alt: false };
+}
+
+/** Mark state dirty and return an empty action list. */
+function mark(state: AppStateRest): Action[] {
+  markDirty(state);
+  return [];
+}
+
+/**
+ * Translate a decoded `KeyEvent` into zero or more `Action` values based on
+ * the current application state.
+ */
+export function handleKey(key: KeyEvent, state: AppStateRest): Action[] {
+  const code = key.code;
+
+  // ── Editor overlay ───────────────────────────────────────────────────
+  if (state.misc.overlay === "editor") {
+    if (code === KeyCode.Char && key.ctrl && (key.value === "c" || key.value === "s")) {
+      return [{ tag: "QuitConfirm" }];
+    }
+    if (code === KeyCode.Esc) {
+      state.misc.editor = null;
+      state.misc.overlay = "none";
+      return [];
+    }
+    if (code === KeyCode.Backspace) {
+      if (state.misc.editor) {
+        state.misc.editor.deleteLeft();
+        mark(state);
+      }
+      return [];
+    }
+    if (code === KeyCode.Enter) {
+      if (state.misc.editor) {
+        state.misc.editor.content =
+          state.misc.editor.content.slice(0, state.misc.editor.cursor) +
+          "\n" +
+          state.misc.editor.content.slice(state.misc.editor.cursor);
+        state.misc.editor.cursor += 1;
+        mark(state);
+      }
+      return [];
+    }
+    if (code === KeyCode.Char && key.value) {
+      if (state.misc.editor) {
+        state.misc.editor.content =
+          state.misc.editor.content.slice(0, state.misc.editor.cursor) +
+          key.value +
+          state.misc.editor.content.slice(state.misc.editor.cursor);
+        state.misc.editor.cursor += key.value.length;
+        mark(state);
+      }
+      return [];
+    }
+    return [];
+  }
+
+  // ── Diff overlay ─────────────────────────────────────────────────────
+  if (state.misc.overlay === "diff") {
+    if (code === KeyCode.Char && key.ctrl && key.value === "c") return [{ tag: "QuitConfirm" }];
+    if (code === KeyCode.Up || (code === KeyCode.Char && key.value === "k")) {
+      return [{ tag: "DiffScroll", amount: -1 }];
+    }
+    if (code === KeyCode.Down || (code === KeyCode.Char && key.value === "j")) {
+      return [{ tag: "DiffScroll", amount: 1 }];
+    }
+    if (code === KeyCode.PageUp) return [{ tag: "DiffScroll", amount: -20 }];
+    if (code === KeyCode.PageDown) return [{ tag: "DiffScroll", amount: 20 }];
+    if (code === KeyCode.Esc) return [{ tag: "CloseOverlay" }];
+    return [];
+  }
+
+  // ── Learning overlay ─────────────────────────────────────────────────
+  if (state.misc.overlay === "learning") {
+    if (code === KeyCode.Char && key.ctrl && key.value === "c") return [{ tag: "QuitConfirm" }];
+    if (code === KeyCode.Esc) return [{ tag: "CloseOverlay" }];
+    if (code === KeyCode.Up) {
+      state.misc.selectedIndex = cycleSelectedIndex(state.misc.selectedIndex, 10, false);
+      return mark(state);
+    }
+    if (code === KeyCode.Down) {
+      state.misc.selectedIndex = cycleSelectedIndex(state.misc.selectedIndex, 10, true);
+      return mark(state);
+    }
+    if (code === KeyCode.Enter || (code === KeyCode.Char && key.value === "a")) {
+      return [{ tag: "LessonAccept", name: `lesson-${state.misc.selectedIndex}` }];
+    }
+    if (code === KeyCode.Char && key.value === "r") {
+      return [{ tag: "LessonReject", name: `lesson-${state.misc.selectedIndex}` }];
+    }
+    if (code === KeyCode.Char && key.value === "d") {
+      return [{ tag: "LessonDelete", name: `lesson-${state.misc.selectedIndex}` }];
+    }
+    return [];
+  }
+
+  // ── Normal (non-overlay) dispatch ────────────────────────────────────
+  switch (code) {
+    case KeyCode.Char:
+      if (key.ctrl && key.value === "c") return [{ tag: "QuitConfirm" }];
+      if (key.ctrl && key.value === "d") return [{ tag: "CloseOverlay" }];
+      if (key.ctrl && key.value === "y") {
+        const lastAssistant = [...state.transcriptCache.messages]
+          .reverse()
+          .find((m) => m.role === Roles.Assistant);
+        if (lastAssistant) {
+          state.misc.pendingClipboardCopy = lastAssistant.content;
+        } else {
+          toastInfo(state, "No assistant message to copy yet");
+        }
+        return [];
+      }
+      if (key.alt) return [{ tag: "ShowDiff" }];
+      // Regular char insertion
+      if (state.input.autocompleteVisible) {
+        state.input.closeAutocomplete();
+        mark(state);
+      }
+      if (key.value) state.input.insert(key.value);
+      mark(state);
+      if (state.input.buffer.startsWith("/")) {
+        state.input.openAutocomplete();
+      } else if (state.input.mentionQueryAtCursor()) {
+        state.input.openMentionAutocomplete(state.mentionFiles);
+      }
+      return [];
+    case KeyCode.Enter:
+      if (state.input.autocompleteVisible) {
+        state.input.selectAutocomplete();
+        return mark(state);
+      }
+      if (overlayIsActive(state.misc.overlay)) {
+        return []; // handle_overlay_enter (simplified: no-op)
+      }
+      {
+        const text = state.input.buffer;
+        if (text.startsWith("/")) {
+          return applyCommand(parseCommand(text));
+        }
+        return [{ tag: "SubmitInput", text }];
+      }
+    case KeyCode.Backspace:
+      if (state.input.autocompleteVisible) {
+        state.input.closeAutocomplete();
+        return mark(state);
+      }
+      return [{ tag: "DeleteChar" }];
+    case KeyCode.Delete:
+      if (state.input.autocompleteVisible) {
+        state.input.closeAutocomplete();
+        return mark(state);
+      }
+      return [{ tag: "DeleteCharRight" }];
+    case KeyCode.Left:
+      return [{ tag: "CursorLeft" }];
+    case KeyCode.Right:
+      return [{ tag: "CursorRight" }];
+    case KeyCode.Up:
+      if (state.input.autocompleteVisible) {
+        state.input.cycleAutocomplete(false);
+        mark(state);
+        return [];
+      } else if (state.misc.overlay === "model_selector") {
+        state.misc.selectedIndex = cycleSelectedIndex(
+          state.misc.selectedIndex,
+          Object.keys(state.appConfig.providers).length,
+          false,
+        );
+        mark(state);
+        return [];
+      } else if (key.ctrl) {
+        return [{ tag: "ScrollUp" }];
+      } else {
+        return [{ tag: "HistoryUp" }];
+      }
+    case KeyCode.Down:
+      if (state.input.autocompleteVisible) {
+        state.input.cycleAutocomplete(true);
+        mark(state);
+        return [];
+      } else if (state.misc.overlay === "model_selector") {
+        state.misc.selectedIndex = cycleSelectedIndex(
+          state.misc.selectedIndex,
+          Object.keys(state.appConfig.providers).length,
+          true,
+        );
+        mark(state);
+        return [];
+      } else if (key.ctrl) {
+        return [{ tag: "ScrollDown" }];
+      } else {
+        return [{ tag: "HistoryDown" }];
+      }
+    case KeyCode.PageUp:
+      return [{ tag: "ScrollUp" }];
+    case KeyCode.PageDown:
+      return [{ tag: "ScrollDown" }];
+    case KeyCode.Esc:
+      if (turnInFlightLocal(state)) return [{ tag: "AbortTurn" }];
+      else if (state.input.autocompleteVisible) {
+        state.input.closeAutocomplete();
+        mark(state);
+        return [];
+      } else if (overlayIsActive(state.misc.overlay)) {
+        return [{ tag: "CloseOverlay" }];
+      }
+      return [];
+    case KeyCode.Tab:
+      if (state.input.buffer.startsWith("/")) {
+        if (state.input.autocompleteVisible) {
+          state.input.cycleAutocomplete(true);
+        } else {
+          state.input.tabComplete();
+        }
+        mark(state);
+      } else if (
+        state.input.autocompleteKind === AutocompleteKind.FileMention &&
+        state.input.autocompleteVisible
+      ) {
+        state.input.cycleAutocomplete(true);
+        mark(state);
+      }
+      return [];
+    default:
+      return [];
+  }
+}
+
+/** Local helper: whether an agent turn is in flight. */
+function turnInFlightLocal(state: AppStateRest): boolean {
+  return state.turnInFlightFlag.value;
+}
+
+/** Cycle a selected index within `n` items (forward or backward). */
+export function cycleSelectedIndex(idx: number, n: number, forward: boolean): number {
+  if (n <= 0) return 0;
+  if (forward) {
+    return (idx + 1) % n;
+  }
+  return idx === 0 ? n - 1 : idx - 1;
+}
diff --git a/apps/interfaces/tui/src/git.ts b/apps/interfaces/tui/src/git.ts
new file mode 100644
index 0000000..9665b69
--- /dev/null
+++ b/apps/interfaces/tui/src/git.ts
@@ -0,0 +1,26 @@
+/**
+ * Git diff preview helper — shells out to `git diff` over the workspace
+ * roots and returns the combined output text. Mirrors
+ * `apps/interfaces/tui/src/action/git.rs`.
+ */
+import { execSync } from "node:child_process";
+
+/** Run `git diff` across the given workspace roots and return the output. */
+export function gitDiffOutput(workspaceRoots: string[]): string {
+  for (const root of workspaceRoots) {
+    try {
+      const out = execSync("git diff --stat && git diff", {
+        cwd: root,
+        encoding: "utf8",
+        maxBuffer: 4 * 1024 * 1024,
+        stdio: ["ignore", "pipe", "ignore"],
+      });
+      if (out.trim().length > 0) {
+        return out;
+      }
+    } catch {
+      // Not a git repo or git not available — continue to the next root.
+    }
+  }
+  return "No diff available (not a git repository).";
+}
diff --git a/apps/interfaces/tui/src/index.ts b/apps/interfaces/tui/src/index.ts
new file mode 100644
index 0000000..1fc1cb1
--- /dev/null
+++ b/apps/interfaces/tui/src/index.ts
@@ -0,0 +1,31 @@
+/**
+ * Zesdex TUI interface — logic-pure interactive layer + lightweight renderer.
+ * Mirrors `apps/interfaces/tui/`.
+ */
+export type { Action } from "./action.ts";
+export { applyAction } from "./action.ts";
+export type { Command } from "./command.ts";
+export { parseCommand, applyCommand } from "./command.ts";
+export type { KeyEvent } from "./controller.ts";
+export { handleKey, decodeKey, cycleSelectedIndex } from "./controller.ts";
+export {
+  createTuiState,
+  AutocompleteKind,
+  Overlay,
+  COMMANDS,
+  DEFAULT_HELP_TEXT,
+  TranscriptCache,
+  InputState,
+  EditorState,
+  ScrollState,
+  MiscState,
+  pushTranscript,
+  appendToLastTranscript,
+  makeChatMessage,
+  toastInfo,
+  toastError,
+  turnInFlight,
+} from "./state.ts";
+export type { AppStateRest, ChatMessageDisplay } from "./state.ts";
+export { renderFrame } from "./render.ts";
+export { gitDiffOutput } from "./git.ts";
diff --git a/apps/interfaces/tui/src/main.ts b/apps/interfaces/tui/src/main.ts
new file mode 100644
index 0000000..130a03e
--- /dev/null
+++ b/apps/interfaces/tui/src/main.ts
@@ -0,0 +1,8 @@
+#!/usr/bin/env bun
+/**
+ * Zesdex TUI — standalone entry point.
+ * Mirrors the default (TUI) mode of the Rust gateway.
+ */
+import { runTui } from "./run.ts";
+
+void runTui();
diff --git a/apps/interfaces/tui/src/render.ts b/apps/interfaces/tui/src/render.ts
new file mode 100644
index 0000000..2f5748e
--- /dev/null
+++ b/apps/interfaces/tui/src/render.ts
@@ -0,0 +1,116 @@
+/**
+ * Lightweight line-based terminal renderer for the TUI. Renders the
+ * `AppStateRest` transcript, input line, overlay, and status into an array of
+ * plain-text + ANSI escaped lines. No external ncurses dependency — outputs
+ * raw ANSI sequences that work in any terminal. Conceptually mirrors
+ * `apps/interfaces/tui/src/view/**` but simplified to line output.
+ */
+import { Roles } from "@zesdex/domain";
+import type { AppStateRest } from "./state.ts";
+import { Overlay } from "./state.ts";
+
+const roleLabel: Record<string, string> = {
+  [Roles.User]: "you",
+  [Roles.Assistant]: "zesdex",
+  [Roles.System]: "system",
+  [Roles.Tool]: "tool",
+};
+
+/** Render the full TUI frame into an array of lines (with ANSI colours). */
+export function renderFrame(state: AppStateRest, height: number, width: number): string[] {
+  const lines: string[] = [];
+
+  // Header bar.
+  lines.push(renderHeader(state, width));
+
+  // Transcript pane.
+  const transcriptLines = renderTranscript(state, width);
+  lines.push(...transcriptLines);
+
+  // Padding to fill remaining height.
+  const used = lines.length;
+  for (let i = used; i < height - 3; i++) {
+    lines.push("");
+  }
+
+  // Overlay content (if any) replaces the input area.
+  if (state.misc.overlay !== Overlay.None) {
+    lines.push(renderOverlay(state, width));
+  } else {
+    lines.push(renderInput(state, width));
+  }
+
+  // Status/footer bar.
+  lines.push(renderStatus(state, width));
+
+  return lines.slice(0, height);
+}
+
+function renderHeader(_state: AppStateRest, width: number): string {
+  const title = " zesdex ";
+  const pad = Math.max(0, width - title.length);
+  return `\x1b[1;44m${title}\x1b[0m${" ".repeat(pad)}`;
+}
+
+function renderTranscript(state: AppStateRest, width: number): string[] {
+  const out: string[] = [];
+  const messages = state.transcriptCache.messages;
+  // Honour scroll offset from the bottom like a typical chat TUI.
+  const start = Math.max(0, messages.length - 30 - state.scroll.offset);
+  for (let i = start; i < messages.length; i++) {
+    const m = messages[i];
+    if (!m) continue;
+    const label = (roleLabel[m.role] ?? m.role).padEnd(8);
+    const color = m.role === Roles.User ? "\x1b[36m" : m.role === Roles.System ? "\x1b[33m" : "\x1b[32m";
+    out.push(`${color}${label}\x1b[0m ${m.content}`);
+    if (m.reasoning) {
+      out.push(`  \x1b[2m(reasoning) ${m.reasoning}\x1b[0m`);
+    }
+  }
+  void width;
+  return out;
+}
+
+function renderInput(state: AppStateRest, width: number): string {
+  const prompt = "> ";
+  const shown = state.input.buffer.length > width - prompt.length
+    ? state.input.buffer.slice(state.input.buffer.length - (width - prompt.length))
+    : state.input.buffer;
+  let line = `\x1b[1m${prompt}\x1b[0m${shown}`;
+  // Append autocomplete hint if visible.
+  if (state.input.autocompleteVisible && state.input.autocompleteCandidates[state.input.autocompleteIdx]) {
+    const cand = state.input.autocompleteCandidates[state.input.autocompleteIdx];
+    line += `  \x1b[2m[tab: ${cand}]\x1b[0m`;
+  }
+  // Toasts.
+  for (const t of state.misc.toasts.slice(-2)) {
+    line += `  \x1b[3m(${t.message})\x1b[0m`;
+  }
+  return line.length > width ? line.slice(0, width) : line;
+}
+
+function renderOverlay(state: AppStateRest, width: number): string {
+  const name = state.misc.overlay;
+  if (name === "diff") {
+    const diffLines = state.misc.diffContent.split("\n");
+    const from = state.misc.diffScroll;
+    return diffLines.slice(from, from + 10).join("\n  ");
+  }
+  if (name === "quit_confirm") {
+    return " \x1b[1;31mQuit?\x1b[0m  (y=yes)  \x1b[2mCtrl+C again / /quit to confirm\x1b[0m";
+  }
+  if (name === "help") {
+    return state.helpText;
+  }
+  void width;
+  return ` \x1b[1mOverlay: ${name}\x1b[0m  \x1b[2m(Esc to close)\x1b[0m`;
+}
+
+function renderStatus(state: AppStateRest, width: number): string {
+  const left = ` model=${(state.settings as { provider?: string }).provider ?? "?"}`;
+  const right = state.turnInFlightFlag.value
+    ? " \x1b[5m● running\x1b[0m"
+    : " \x1b[2m● idle\x1b[0m";
+  const combined = `${left}${right}`;
+  return combined.length > width ? combined.slice(0, width) : combined;
+}
diff --git a/apps/interfaces/tui/src/run.ts b/apps/interfaces/tui/src/run.ts
new file mode 100644
index 0000000..4404144
--- /dev/null
+++ b/apps/interfaces/tui/src/run.ts
@@ -0,0 +1,145 @@
+#!/usr/bin/env bun
+/**
+ * Zesdex TUI — interactive event loop.
+ *
+ * Reads keys from the terminal in raw mode, decodes them into `KeyEvent`s,
+ * routes through `handleKey` → `applyAction`, and re-renders the frame.
+ * Streaming agent output is applied to the transcript via
+ * `appendToLastTranscript`.
+ *
+ * Mirrors the conceptual flow of `apps/interfaces/tui/src/run.rs` (event
+ * loop + turn drain) using a plain raw-mode stdin reader instead of
+ * crossterm/ratatui.
+ */
+import * as fs from "node:fs";
+import { createTuiState, pushTranscript, appendToLastTranscript, makeChatMessage } from "./state.ts";
+import { applyAction } from "./action.ts";
+import type { Action } from "./action.ts";
+import { decodeKey, handleKey } from "./controller.ts";
+import type { KeyEvent } from "./controller.ts";
+import { renderFrame } from "./render.ts";
+import { Roles } from "@zesdex/domain";
+
+function readRaw(): () => void {
+  const prev = { ...(process.stdout as unknown as { attrs?: unknown }) };
+  const stdin = process.stdin as unknown as { setRawMode: (b: boolean) => void };
+  if (typeof stdin.setRawMode === "function") stdin.setRawMode(true);
+  // Show cursor-off control sequences are handled at frame draw.
+  void prev;
+  return () => {
+    if (typeof stdin.setRawMode === "function") stdin.setRawMode(false);
+    process.stdout.write("\x1b[?25h\x1b[0m"); // show cursor + reset
+  };
+}
+
+/** Run the interactive TUI until the user quits. */
+export async function runTui(): Promise<void> {
+  const cwd = process.cwd();
+  const dataDir = `${process.env.HOME ?? ""}/.local/share/zesdex`;
+  const sessionDir = `${dataDir}/sessions/${Date.now()}`;
+  fs.mkdirSync(sessionDir, { recursive: true });
+
+  const state = createTuiState([cwd], sessionDir, `${dataDir}/memory`);
+  const restore = readRaw();
+
+  // Seed some transcript so the pane isn't empty on first render.
+  pushTranscript(state, makeChatMessage(Roles.System, "Zesdex ready. Type a message or /help."));
+
+  const stdin = process.stdin as unknown as {
+    setRawMode: (b: boolean) => void;
+    on: (ev: string, cb: (chunk: Buffer) => void) => void;
+    resume: () => void;
+  };
+  stdin.resume();
+
+  let buffer = "";
+  stdin.on("data", (chunk: Buffer) => {
+    buffer += chunk.toString("utf8");
+    // Process complete escape sequences (each is self-contained).
+    while (buffer.length > 0) {
+      const ev = decodeKey(buffer);
+      if (!ev) {
+        // Might be a partial escape sequence; wait for more bytes.
+        break;
+      }
+      // consume the decoded sequence length
+      const consumed = consumedLen(buffer, ev);
+      buffer = buffer.slice(consumed);
+      dispatch(ev, state);
+    }
+    draw(state);
+  });
+
+  // Turn drain: poll a fake "in-flight" by checking pendingSubmit periodically.
+  const drainTimer = setInterval(() => {
+    if (state.pendingSubmit !== null) {
+      const text = state.pendingSubmit;
+      state.pendingSubmit = null;
+      state.turnInFlightFlag.value = true;
+      state.dirty = true;
+      // With no live LLM wiring in the pure TUI, simulate a short "thinking"
+      // then append a fixed assistant note. Real wiring happens in the CLI.
+      setTimeout(() => {
+        state.turnInFlightFlag.value = false;
+        appendToLastTranscript(state, `(no LLM configured — processed: "${text}")`, false);
+        state.dirty = true;
+        draw(state);
+      }, 50);
+    }
+    if (state.dirty) draw(state);
+  }, 100);
+
+  draw(state);
+
+  // Block until quit.
+  await new Promise<void>((resolve) => {
+    const check = setInterval(() => {
+      if (state.quit) {
+        clearInterval(check);
+        clearInterval(drainTimer);
+        restore();
+        resolve();
+      }
+    }, 50);
+  });
+}
+
+/** Determine how many characters of the input buffer a decoded event consumed. */
+function consumedLen(buffer: string, _ev: KeyEvent): number {
+  // Escape sequences are multi-byte; a plain char is 1 codepoint.
+  if (buffer.startsWith("\u001b[")) {
+    // consume through the terminating letter (~ or A-D).
+    const m = buffer.match(/^\u001b\[([0-9;]*)([A-Z~])/);
+    return m ? m[0].length : buffer.length;
+  }
+  if (buffer.startsWith("\u001b")) {
+    return buffer.length; // alt sequence
+  }
+  return [...buffer][0]!.length;
+}
+
+/** Dispatch a decoded key via the controller and apply resulting actions. */
+function dispatch(key: KeyEvent, state: ReturnType<typeof createTuiState>): void {
+  const actions = handleKey(key, state);
+  for (const action of actions) {
+    const act = action as Action;
+    if (act.tag === "QuitConfirm") {
+      // Go straight to quit on Ctrl+C (simplified confirm).
+      state.quit = true;
+      continue;
+    }
+    applyAction(state, act);
+  }
+}
+
+/** Draw the current frame. */
+function draw(state: ReturnType<typeof createTuiState>): void {
+  if (!state.dirty) return;
+  state.dirty = false;
+  const h = process.stdout.rows ?? 24;
+  const w = process.stdout.columns ?? 80;
+  const lines = renderFrame(state, h, w);
+  process.stdout.write("\x1b[2J\x1b[H"); // clear + home
+  process.stdout.write(lines.join("\n"));
+  process.stdout.write("\x1b[?25h");
+}
diff --git a/apps/interfaces/tui/src/state.ts b/apps/interfaces/tui/src/state.ts
new file mode 100644
index 0000000..84fdefd
--- /dev/null
+++ b/apps/interfaces/tui/src/state.ts
@@ -0,0 +1,511 @@
+/**
+ * TUI state — the single source-of-truth struct for the TUI interface plus
+ * all the types it owns. Mirrors `apps/interfaces/tui/src/state/**`.
+ *
+ * Design: `AppStateRest` is mutated by `applyAction` and read by the renderer
+ * each frame. Everything here is logic-pure (no terminal I/O), so it is
+ * unit-testable in Bun.
+ */
+
+import { Roles, type Role } from "@zesdex/domain";
+
+/* ── Input state ──────────────────────────────────────────────────── */
+
+/** Which source populated the autocomplete dropdown. */
+export const AutocompleteKind = {
+  Command: "command",
+  FileMention: "file_mention",
+} as const;
+export type AutocompleteKind = (typeof AutocompleteKind)[keyof typeof AutocompleteKind];
+
+/** Builtin slash-commands recognised by the chat input autocomplete. */
+export const COMMANDS: string[] = [
+  "/help",
+  "/quit",
+  "/clear",
+  "/login",
+  "/login zen",
+  "/login openai",
+  "/edit",
+  "/mcp add",
+  "/model",
+  "/model ls",
+  "/model add",
+  "/todo",
+  "/usage",
+  "/compact",
+];
+
+/** The user's input buffer, cursor, history, and autocomplete state. */
+export class InputState {
+  buffer = "";
+  cursor = 0;
+  history: string[] = [];
+  historyIdx: number | null = null;
+  autocompleteCandidates: string[] = [];
+  autocompleteIdx = 0;
+  autocompleteVisible = false;
+  autocompleteKind: AutocompleteKind = AutocompleteKind.Command;
+  mentionStart = 0;
+  historyFile: string | null = null;
+
+  /** Hide the autocomplete dropdown and clear its state. */
+  closeAutocomplete(): void {
+    this.autocompleteVisible = false;
+    this.autocompleteCandidates = [];
+    this.autocompleteIdx = 0;
+    this.autocompleteKind = AutocompleteKind.Command;
+    this.mentionStart = 0;
+  }
+
+  /** Open or refresh the autocomplete dropdown by filtering COMMANDS. */
+  openAutocomplete(): void {
+    const trimmed = this.buffer.trim();
+    if (trimmed.length === 0 || !trimmed.startsWith("/")) {
+      this.closeAutocomplete();
+      return;
+    }
+    const prefix = trimmed.toLowerCase();
+    this.autocompleteCandidates = COMMANDS.filter((c) => c.startsWith(prefix));
+    this.autocompleteKind = AutocompleteKind.Command;
+    this.autocompleteIdx = 0;
+    this.autocompleteVisible = this.autocompleteCandidates.length > 0;
+  }
+
+  /** Find the `@mention` token (if any) immediately before the cursor. */
+  mentionQueryAtCursor(): [number, string] | null {
+    const beforeCursor = this.buffer.slice(0, this.cursor);
+    const atPos = beforeCursor.lastIndexOf("@");
+    if (atPos === -1) return null;
+    const between = beforeCursor.slice(atPos + 1);
+    if (/[\s]/.test(between)) return null;
+    const boundaryOk =
+      atPos === 0 || /[\s]/.test(beforeCursor[atPos - 1] ?? "") || /\s/.test(beforeCursor[atPos - 1] ?? "");
+    if (!boundaryOk) return null;
+    return [atPos, between];
+  }
+
+  /** Open or refresh the `@file` mention dropdown from `files`. */
+  openMentionAutocomplete(files: string[]): void {
+    const q = this.mentionQueryAtCursor();
+    if (!q) {
+      this.closeAutocomplete();
+      return;
+    }
+    const [, query] = q;
+    const ql = query.toLowerCase();
+    // Simple substring + prefix fuzzy match over the file list.
+    const matched = files
+      .filter((f) => {
+        const fl = f.toLowerCase();
+        return fl.includes(ql) || f.replace(/.*\//, "").toLowerCase().startsWith(ql);
+      })
+      .slice(0, 10);
+    this.autocompleteCandidates = matched;
+    this.autocompleteKind = AutocompleteKind.FileMention;
+    this.mentionStart = q[0];
+    this.autocompleteIdx = 0;
+    this.autocompleteVisible = matched.length > 0;
+  }
+
+  /** Move the autocomplete selection up (false) or down (true). */
+  cycleAutocomplete(forward: boolean): void {
+    const n = this.autocompleteCandidates.length;
+    if (n === 0) return;
+    if (forward) {
+      this.autocompleteIdx = (this.autocompleteIdx + 1) % n;
+    } else {
+      this.autocompleteIdx =
+        this.autocompleteIdx === 0 ? n - 1 : this.autocompleteIdx - 1;
+    }
+  }
+
+  /** Accept the currently selected autocomplete candidate. Returns true on success. */
+  selectAutocomplete(): boolean {
+    const candidate = this.autocompleteCandidates[this.autocompleteIdx];
+    if (candidate === undefined || candidate === null) return false;
+    if (this.autocompleteKind === AutocompleteKind.Command) {
+      this.buffer = candidate;
+      this.cursor = this.buffer.length;
+    } else {
+      if (this.cursor < this.mentionStart || this.mentionStart > this.buffer.length) {
+        this.closeAutocomplete();
+        return false;
+      }
+      const replacement = `@${candidate} `;
+      this.buffer =
+        this.buffer.slice(0, this.mentionStart) + replacement + this.buffer.slice(this.cursor);
+      this.cursor = this.mentionStart + replacement.length;
+    }
+    this.closeAutocomplete();
+    return true;
+  }
+
+  /** Tab-complete: open dropdown or cycle forward. */
+  tabComplete(): void {
+    if (this.autocompleteVisible) {
+      this.cycleAutocomplete(true);
+    } else {
+      this.openAutocomplete();
+    }
+  }
+
+  /** Insert a character at the cursor position. */
+  insert(c: string): void {
+    this.buffer = this.buffer.slice(0, this.cursor) + c + this.buffer.slice(this.cursor);
+    this.cursor += c.length;
+  }
+
+  /** Delete the character to the left of the cursor (backspace). */
+  deleteLeft(): void {
+    if (this.cursor > 0) {
+      this.cursor -= 1;
+      this.buffer = this.buffer.slice(0, this.cursor) + this.buffer.slice(this.cursor + 1);
+    }
+  }
+
+  /** Delete the character at the cursor position (forward delete). */
+  deleteRight(): void {
+    if (this.cursor < this.buffer.length) {
+      this.buffer = this.buffer.slice(0, this.cursor) + this.buffer.slice(this.cursor + 1);
+    }
+  }
+
+  /** Submit the current buffer and return the submitted text. */
+  submit(): string {
+    const result = this.buffer;
+    if (result.length > 0) {
+      if (this.history[this.history.length - 1] !== result) {
+        this.history.push(result);
+      }
+      this.historyIdx = null;
+    }
+    this.buffer = "";
+    this.cursor = 0;
+    return result;
+  }
+
+  /** Navigate backward through input history. */
+  historyUp(): void {
+    if (this.history.length === 0) return;
+    let idx: number;
+    if (this.historyIdx !== null && this.historyIdx > 0) {
+      idx = this.historyIdx - 1;
+    } else if (this.historyIdx === null) {
+      idx = this.history.length - 1;
+    } else {
+      return;
+    }
+    this.historyIdx = idx;
+    this.buffer = this.history[idx] ?? "";
+    this.cursor = this.buffer.length;
+  }
+
+  /** Navigate forward through input history. */
+  historyDown(): void {
+    if (this.historyIdx !== null && this.historyIdx < this.history.length - 1) {
+      const idx = this.historyIdx + 1;
+      this.historyIdx = idx;
+      this.buffer = this.history[idx] ?? "";
+      this.cursor = this.buffer.length;
+    } else if (this.historyIdx !== null) {
+      this.historyIdx = null;
+      this.buffer = "";
+      this.cursor = 0;
+    }
+    // else nothing to do
+  }
+}
+
+/* ── Overlay ──────────────────────────────────────────────────────── */
+
+/** Which modal overlay, if any, is currently shown over the main TUI view. */
+export const Overlay = {
+  None: "none",
+  Help: "help",
+  Settings: "settings",
+  Bash: "bash",
+  QuitConfirm: "quit_confirm",
+  KeyInput: "key_input",
+  Editor: "editor",
+  Effort: "effort",
+  Mcp: "mcp",
+  Todo: "todo",
+  Plan: "plan",
+  Rewind: "rewind",
+  Learning: "learning",
+  Usage: "usage",
+  Loading: "loading",
+  ModelSelector: "model_selector",
+  ClearConfirm: "clear_confirm",
+  Diff: "diff",
+} as const;
+export type Overlay = (typeof Overlay)[keyof typeof Overlay];
+
+export function overlayIsActive(overlay: Overlay): boolean {
+  return overlay !== Overlay.None;
+}
+
+/* ── Editor state ─────────────────────────────────────────────────── */
+
+/** Simple inline editor state for the TUI. */
+export class EditorState {
+  constructor(
+    public path: string,
+    public content: string,
+    public cursor: number = content.length,
+  ) {}
+
+  asString(): string {
+    return this.content;
+  }
+
+  deleteLeft(): void {
+    if (this.cursor > 0) {
+      this.cursor -= 1;
+      this.content = this.content.slice(0, this.cursor) + this.content.slice(this.cursor + 1);
+    }
+  }
+}
+
+/* ── Misc state ───────────────────────────────────────────────────── */
+
+/** The "miscellaneous" slice of app state. */
+export class MiscState {
+  overlay: Overlay = Overlay.None;
+  toasts: { kind: string; message: string; createdMs: number; ttlMs: number }[] = [];
+  lastStalenessSweepMs = 0;
+  thinking = false;
+  effortLevel = 1;
+  selectedIndex = 0;
+  editor: EditorState | null = null;
+  apiConnected = false;
+  tickCount = 0;
+  todoContent = "";
+  planContent = "";
+  lessonRunning = false;
+  pendingClipboardCopy: string | null = null;
+  diffContent = "";
+  diffScroll = 0;
+
+  pushToast(toast: { kind: string; message: string; createdMs: number; ttlMs: number }): void {
+    this.toasts.push(toast);
+  }
+
+  drainExpiredToasts(nowMs: number): void {
+    this.toasts = this.toasts.filter((t) => !(nowMs - t.createdMs >= t.ttlMs));
+  }
+}
+
+/* ── Scroll state ─────────────────────────────────────────────────── */
+
+/** Viewport scroll state: current offset and visible-line count. */
+export class ScrollState {
+  offset = 0;
+  maxVisible = 30;
+
+  scrollUp(amount: number): void {
+    this.offset += amount;
+  }
+  scrollDown(amount: number): void {
+    this.offset = Math.max(0, this.offset - amount);
+  }
+}
+
+/* ── Transcript ───────────────────────────────────────────────────── */
+
+/** A single transcript entry rendered in the TUI chat pane. */
+export interface ChatMessageDisplay {
+  role: Role;
+  content: string;
+  reasoning: string;
+  timestamp: number;
+}
+
+export function makeChatMessage(role: Role, content: string): ChatMessageDisplay {
+  return { role, content, reasoning: "", timestamp: Date.now() };
+}
+
+/** Bounded ring of recent chat messages used to render the transcript view. */
+export class TranscriptCache {
+  messages: ChatMessageDisplay[] = [];
+  maxLines: number;
+  dirty = true;
+
+  constructor(maxLines = 200) {
+    this.maxLines = maxLines;
+  }
+
+  push(msg: ChatMessageDisplay): void {
+    this.messages.push(msg);
+    while (this.messages.length > this.maxLines) {
+      this.messages.shift();
+    }
+    this.dirty = true;
+  }
+
+  appendToLast(text: string, isReasoning: boolean): void {
+    const msg = this.messages[this.messages.length - 1];
+    if (msg && msg.role === Roles.Assistant) {
+      if (isReasoning) {
+        msg.reasoning += text;
+      } else {
+        msg.content += text;
+      }
+      this.dirty = true;
+    }
+  }
+}
+
+/* ── AppStateRest ─────────────────────────────────────────────────── */
+
+/**
+ * The single source-of-truth state struct for the TUI interface.
+ * Mutated via `applyAction`; read by the renderer every frame.
+ */
+export interface AppStateRest {
+  settings: Record<string, unknown>;
+  appConfig: { providers: Record<string, { apiBase?: string; defaultApiKey?: string; apiKeyEnv?: string }> };
+  workspaceRoots: string[];
+  sessionId: string;
+  sessionDir: string;
+  memoryDir: string;
+  worktreesDir: string;
+  transcriptCache: TranscriptCache;
+  scroll: ScrollState;
+  input: InputState;
+  misc: MiscState;
+  turnInFlightFlag: { value: boolean };
+  abortFlag: { value: boolean };
+  dirty: boolean;
+  quit: boolean;
+  helpText: string;
+  displayLinesCache: string[];
+  cachedTokenCount: number;
+  tokenCountDirty: boolean;
+  lastRenderWidth: number;
+  cachedMsgCount: number;
+  cachedLastStart: number;
+  cachedLastLen: number;
+  renderWidthAtCache: number;
+  mentionFiles: string[];
+  pendingSubmit: string | null; // set when a turn should be spawned
+}
+
+export const DEFAULT_HELP_TEXT = ` Zesdex TUI — Keyboard Shortcuts
+
+ ─── General ───
+  Ctrl+C        Quit confirm
+  Ctrl+D        Close overlay
+  Ctrl+Y        Copy last assistant message
+  Esc           Abort turn / Close overlay
+  Tab           Autocomplete
+
+ ─── Navigation ───
+  ↑ / ↓         History browse / Overlay navigate
+  Ctrl+↑/↓      Scroll transcript
+  PgUp / PgDown Scroll transcript
+  Enter         Submit / Select autocomplete
+
+ ─── Overlays ───
+  /help         Show this help
+  /settings     Open settings overlay
+  /todo         Open tasks (todo) overlay
+  /usage        Open usage statistics
+  /bash         Open bash jobs overlay
+  /mcp          Open MCP server management
+  /model        Open model selector
+  /compact      Compact conversation
+  /clear        Clear transcript
+  /rewind       Rewind conversation history
+
+ ─── Editor Mode ───
+  /edit <path>  Open file for inline editing
+  Ctrl+S        Save changes
+  Esc           Dismiss editor`;
+
+/** Construct fresh TUI state. */
+export function createTuiState(
+  workspaceRoots: string[],
+  sessionDir: string,
+  memoryDir: string,
+): AppStateRest {
+  const sessionId = sessionDir.split(/[/\\]/).filter(Boolean).pop() ?? "";
+  const worktreesDir = memoryDir.replace(/[\\/][^\\/]*$/, "") + "/worktrees";
+  return {
+    settings: { provider: "claude" },
+    appConfig: { providers: {} },
+    workspaceRoots,
+    sessionId,
+    sessionDir,
+    memoryDir,
+    worktreesDir,
+    transcriptCache: new TranscriptCache(200),
+    scroll: new ScrollState(),
+    input: new InputState(),
+    misc: new MiscState(),
+    turnInFlightFlag: { value: false },
+    abortFlag: { value: false },
+    dirty: true,
+    quit: false,
+    helpText: DEFAULT_HELP_TEXT,
+    displayLinesCache: [],
+    cachedTokenCount: 0,
+    tokenCountDirty: true,
+    lastRenderWidth: 0,
+    cachedMsgCount: 0,
+    cachedLastStart: 0,
+    cachedLastLen: 0,
+    renderWidthAtCache: 0,
+    mentionFiles: [],
+    pendingSubmit: null,
+  };
+}
+
+/** Whether an agent turn is currently running. */
+export function turnInFlight(state: AppStateRest): boolean {
+  return state.turnInFlightFlag.value;
+}
+
+/** Append a message to the transcript. */
+export function pushTranscript(state: AppStateRest, msg: ChatMessageDisplay): void {
+  state.transcriptCache.push(msg);
+  state.tokenCountDirty = true;
+  state.dirty = true;
+}
+
+/** Append text to the last assistant message. */
+export function appendToLastTranscript(state: AppStateRest, text: string, isReasoning: boolean): void {
+  state.transcriptCache.appendToLast(text, isReasoning);
+  if (state.transcriptCache.dirty) state.dirty = true;
+}
+
+export function markDirty(state: AppStateRest): void {
+  state.dirty = true;
+}
+
+export function pushToast(
+  state: AppStateRest,
+  toast: { kind: string; message: string; createdMs: number; ttlMs: number },
+): void {
+  state.misc.pushToast(toast);
+  state.dirty = true;
+}
+
+export function toastInfo(state: AppStateRest, message: string): void {
+  pushToast(state, { kind: "info", message, createdMs: Date.now(), ttlMs: 4000 });
+}
+export function toastSuccess(state: AppStateRest, message: string): void {
+  pushToast(state, { kind: "success", message, createdMs: Date.now(), ttlMs: 4000 });
+}
+export function toastWarning(state: AppStateRest, message: string): void {
+  pushToast(state, { kind: "warning", message, createdMs: Date.now(), ttlMs: 4000 });
+}
+export function toastError(state: AppStateRest, message: string): void {
+  pushToast(state, { kind: "error", message, createdMs: Date.now(), ttlMs: 5000 });
+}
+
+/** Resolve the base directory of the store (grandparent of the session dir). */
+export function storeBaseDir(state: AppStateRest): string {
+  return state.sessionDir.replace(/[\\/][^\\/]*[\\/][^\\/]*$/, "");
+}
diff --git a/apps/interfaces/tui/src/tui.test.ts b/apps/interfaces/tui/src/tui.test.ts
new file mode 100644
index 0000000..6bcd94e
--- /dev/null
+++ b/apps/interfaces/tui/src/tui.test.ts
@@ -0,0 +1,127 @@
+/**
+ * Tests for the TUI logic layer: command parsing, action dispatch, and the
+ * key controller. Mirrors the Rust `#[cfg(test)]` blocks.
+ */
+import { describe, test, expect } from "bun:test";
+import { parseCommand, applyCommand } from "./command.ts";
+import { createTuiState, pushTranscript, makeChatMessage } from "./state.ts";
+import { applyAction } from "./action.ts";
+import { handleKey, decodeKey } from "./controller.ts";
+import { Roles } from "@zesdex/domain";
+
+function freshState() {
+  return createTuiState(["/tmp/zesdex-tui-test"], "/tmp/zesdex-tui-test/sess", "/tmp/zesdex-tui-test/mem");
+}
+
+describe("parseCommand", () => {
+  test("recognises /todo", () => {
+    expect(parseCommand("/todo")).toEqual({ tag: "TodoOpen" });
+  });
+  test("recognises /usage", () => {
+    expect(parseCommand("/usage")).toEqual({ tag: "UsageOpen" });
+  });
+  test("non-slash input is Unknown", () => {
+    expect(parseCommand("hello")).toEqual({ tag: "Unknown", text: "hello" });
+  });
+  test("parses /edit path", () => {
+    expect(parseCommand("/edit src/a.ts")).toEqual({ tag: "Edit", path: "src/a.ts" });
+  });
+  test("parses /clear with arg as Clear, without as ClearConfirm", () => {
+    expect(parseCommand("/clear foo")).toEqual({ tag: "Clear" });
+    expect(parseCommand("/clear")).toEqual({ tag: "ClearConfirm" });
+  });
+});
+
+describe("applyCommand", () => {
+  test("Help opens help overlay", () => {
+    expect(applyCommand({ tag: "Help" })).toEqual([{ tag: "OpenOverlay", overlay: "help" }]);
+  });
+  test("Unknown slash produces SystemNote error", () => {
+    expect(applyCommand({ tag: "Unknown", text: "/nope" })).toEqual([
+      { tag: "SystemNote", kind: "error", message: "Unknown command: /nope" },
+    ]);
+  });
+});
+
+describe("applyAction", () => {
+  test("SubmitInput pushes user transcript and sets pendingSubmit", () => {
+    const s = freshState();
+    applyAction(s, { tag: "SubmitInput", text: "hi" });
+    const last = s.transcriptCache.messages[s.transcriptCache.messages.length - 1];
+    expect(last?.role).toBe(Roles.User);
+    expect(last?.content).toBe("hi");
+    expect(s.pendingSubmit).toBe("hi");
+  });
+
+  test("ForceQuit sets quit", () => {
+    const s = freshState();
+    applyAction(s, { tag: "ForceQuit" });
+    expect(s.quit).toBe(true);
+  });
+
+  test("QuitConfirm sets overlay", () => {
+    const s = freshState();
+    applyAction(s, { tag: "QuitConfirm" });
+    expect(s.misc.overlay).toBe("quit_confirm");
+  });
+
+  test("AbortTurn sets abort flag", () => {
+    const s = freshState();
+    applyAction(s, { tag: "AbortTurn" });
+    expect(s.abortFlag.value).toBe(true);
+  });
+});
+
+describe("handleKey", () => {
+  test("Ctrl+C produces QuitConfirm", () => {
+    const s = freshState();
+    const actions = handleKey({ code: "Char", value: "c", ctrl: true, alt: false }, s);
+    expect(actions).toEqual([{ tag: "QuitConfirm" }]);
+  });
+
+  test("typing chars inserts into buffer", () => {
+    const s = freshState();
+    handleKey({ code: "Char", value: "h", ctrl: false, alt: false }, s);
+    handleKey({ code: "Char", value: "i", ctrl: false, alt: false }, s);
+    expect(s.input.buffer).toBe("hi");
+  });
+
+  test("Enter submits input as SubmitInput", () => {
+    const s = freshState();
+    handleKey({ code: "Char", value: "a", ctrl: false, alt: false }, s);
+    const actions = handleKey({ code: "Enter", ctrl: false, alt: false }, s);
+    expect(actions).toEqual([{ tag: "SubmitInput", text: "a" }]);
+  });
+
+  test("Ctrl+Y copies last assistant message", () => {
+    const s = freshState();
+    pushTranscript(s, makeChatMessage(Roles.User, "hi"));
+    pushTranscript(s, makeChatMessage(Roles.Assistant, "first"));
+    pushTranscript(s, makeChatMessage(Roles.Tool, "tool"));
+    pushTranscript(s, makeChatMessage(Roles.Assistant, "second"));
+    handleKey({ code: "Char", value: "y", ctrl: true, alt: false }, s);
+    expect(s.misc.pendingClipboardCopy).toBe("second");
+  });
+
+  test("Ctrl+Y with no assistant pushes info toast", () => {
+    const s = freshState();
+    handleKey({ code: "Char", value: "y", ctrl: true, alt: false }, s);
+    expect(s.misc.pendingClipboardCopy).toBeNull();
+    expect(s.misc.toasts.length).toBe(1);
+  });
+});
+
+describe("decodeKey", () => {
+  test("Enter decodes", () => {
+    expect(decodeKey("\r")).toEqual({ code: "Enter", ctrl: false, alt: false });
+  });
+  test("arrow up decodes", () => {
+    expect(decodeKey("\u001b[A")).toEqual({ code: "ArrowUp", ctrl: false, alt: false });
+  });
+  test("ctrl-c decodes to ctrl Char c", () => {
+    expect(decodeKey("\u0003")).toEqual({ code: "Char", value: "c", ctrl: true, alt: false });
+  });
+  test("plain letter decodes", () => {
+    expect(decodeKey("x")).toEqual({ code: "Char", value: "x", ctrl: false, alt: false });
+  });
+});
diff --git a/bun.lock b/bun.lock
index c0d56b0..773e8f0 100644
--- a/bun.lock
+++ b/bun.lock
@@ -60,6 +60,16 @@
         "@types/bun": "^1.2.0",
       },
     },
+    "apps/interfaces/tui": {
+      "name": "@zesdex/tui",
+      "version": "1.21.2",
+      "dependencies": {
+        "@zesdex/domain": "workspace:*",
+      },
+      "devDependencies": {
+        "@types/bun": "^1.2.0",
+      },
+    },
     "apps/interfaces/web": {
       "name": "@zesdex/web",
       "version": "1.21.2",
@@ -158,6 +168,8 @@
 
     "@zesdex/infrastructure": ["@zesdex/infrastructure@workspace:apps/packages/infrastructure"],
 
+    "@zesdex/tui": ["@zesdex/tui@workspace:apps/interfaces/tui"],
+
     "@zesdex/web": ["@zesdex/web@workspace:apps/interfaces/web"],
 
     "@zesdex/ws": ["@zesdex/ws@workspace:apps/interfaces/ws"],
diff --git a/tsconfig.json b/tsconfig.json
index 18fd0d0..16da892 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -27,7 +27,8 @@
       "@zesdex/ws": ["./apps/interfaces/ws/src/index.ts"],
       "@zesdex/grpc": ["./apps/interfaces/grpc/src/index.ts"],
       "@zesdex/web": ["./apps/interfaces/web/src/index.ts"],
-      "@zesdex/daemon": ["./apps/interfaces/daemon/src/index.ts"]
+      "@zesdex/daemon": ["./apps/interfaces/daemon/src/index.ts"],
+      "@zesdex/tui": ["./apps/interfaces/tui/src/index.ts"]
     }
   },
   "include": ["apps/packages/*/src", "apps/interfaces/*/src", "apps/interfaces/*/bin"]