Fix Shift+Enter in terminal input modes (#999)

* Fix Shift+Enter terminal input modes

* Advertise terminal input capabilities

packages/app/src/components/terminal-emulator.tsx

@@ -17,6 +17,7 @@ import { useDOMImperativeHandle, type DOMImperativeFactory } from "expo/dom";
 import "@xterm/xterm/css/xterm.css";
 import type { ITheme } from "@xterm/xterm";
 import type { TerminalState } from "@server/shared/messages";
+import type { TerminalInputModeState } from "@server/shared/terminal-input-mode";
 import type { PendingTerminalModifiers } from "../utils/terminal-keys";
 import { TerminalEmulatorRuntime } from "../terminal/runtime/terminal-emulator-runtime";
 import type { TerminalRendererReadyChange } from "../utils/terminal-renderer-readiness";
@@ -129,6 +130,7 @@ interface TerminalEmulatorProps {
     meta: boolean;
   }) => Promise<void> | void;
   onPendingModifiersConsumed?: () => Promise<void> | void;
+  onInputModeChange?: (state: TerminalInputModeState) => Promise<void> | void;
   onRendererReadyChange?: (change: TerminalRendererReadyChange) => void;
   pendingModifiers?: PendingTerminalModifiers;
   focusRequestToken?: number;
@@ -194,6 +196,7 @@ export default function TerminalEmulator({
   onResize,
   onTerminalKey,
   onPendingModifiersConsumed,
+  onInputModeChange,
   onRendererReadyChange,
   pendingModifiers = { ctrl: false, shift: false, alt: false },
   focusRequestToken = 0,
@@ -219,12 +222,14 @@ export default function TerminalEmulator({
     onResize,
     onTerminalKey,
     onPendingModifiersConsumed,
+    onInputModeChange,
   });
   mountCallbacksRef.current = {
     onInput,
     onResize,
     onTerminalKey,
     onPendingModifiersConsumed,
+    onInputModeChange,
   };
   const initialSnapshotRef = useRef(initialSnapshot);
   initialSnapshotRef.current = initialSnapshot;
@@ -444,10 +449,11 @@ export default function TerminalEmulator({
         onResize,
         onTerminalKey,
         onPendingModifiersConsumed,
+        onInputModeChange,
         onOpenExternalUrl: openExternalUrl,
       },
     });
-  }, [onInput, onPendingModifiersConsumed, onResize, onTerminalKey]);
+  }, [onInput, onInputModeChange, onPendingModifiersConsumed, onResize, onTerminalKey]);
 
   useEffect(() => {
     runtimeRef.current?.setPendingModifiers({ pendingModifiers });

packages/app/src/components/terminal-pane.tsx

@@ -10,6 +10,7 @@ import {
 import Animated, { runOnJS, useAnimatedReaction } from "react-native-reanimated";
 import { StyleSheet, useUnistyles } from "react-native-unistyles";
 import { encodeTerminalKeyInput } from "@server/shared/terminal-key-input";
+import type { TerminalInputModeState } from "@server/shared/terminal-input-mode";
 import { useHostRuntimeClient, useHostRuntimeIsConnected } from "@/runtime/host-runtime";
 import { useKeyboardShiftStyle } from "@/hooks/use-keyboard-shift-style";
 import { useAppVisible } from "@/hooks/use-app-visible";
@@ -188,6 +189,10 @@ export function TerminalPane({
   const [resizeRequestToken, setResizeRequestToken] = useState(0);
   const emulatorRef = useRef<TerminalEmulatorHandle>(null);
   const terminalIdRef = useRef<string>(terminalId);
+  const inputModeRef = useRef<TerminalInputModeState>({
+    kittyKeyboardFlags: 0,
+    win32InputMode: false,
+  });
   const pendingTerminalInputRef = useRef<PendingTerminalInput[]>([]);
   const keyboardRefitTimeoutsRef = useRef<Array<ReturnType<typeof setTimeout>>>([]);
   const lastAutoFocusKeyRef = useRef<string | null>(null);
@@ -195,6 +200,10 @@ export function TerminalPane({
 
   useEffect(() => {
     terminalIdRef.current = terminalId;
+    inputModeRef.current = {
+      kittyKeyboardFlags: 0,
+      win32InputMode: false,
+    };
   }, [terminalId]);
 
   const requestTerminalFocus = useCallback(() => {
@@ -413,7 +422,9 @@ export function TerminalPane({
         return true;
       }
 
-      const encoded = encodeTerminalKeyInput(entry.input);
+      const encoded = encodeTerminalKeyInput(entry.input, {
+        inputMode: inputModeRef.current,
+      });
       if (encoded.length === 0) {
         return true;
       }
@@ -595,6 +606,10 @@ export function TerminalPane({
     clearPendingModifiers();
   }, [clearPendingModifiers]);
 
+  const handleInputModeChange = useCallback((state: TerminalInputModeState) => {
+    inputModeRef.current = state;
+  }, []);
+
   const toggleModifier = useCallback(
     (modifier: keyof ModifierState) => {
       setModifiers((current) => ({ ...current, [modifier]: !current[modifier] }));
@@ -674,6 +689,7 @@ export function TerminalPane({
               onInput={handleTerminalData}
               onResize={handleTerminalResize}
               onTerminalKey={handleTerminalKey}
+              onInputModeChange={handleInputModeChange}
               onPendingModifiersConsumed={handlePendingModifiersConsumed}
               pendingModifiers={modifiers}
               focusRequestToken={focusRequestToken}

packages/app/src/terminal/runtime/terminal-emulator-runtime.browser.test.ts

@@ -1,5 +1,6 @@
 import { page } from "@vitest/browser/context";
 import { afterEach, describe, expect, it, vi } from "vitest";
+import type { TerminalInputModeState } from "@server/shared/terminal-input-mode";
 import { TerminalEmulatorRuntime } from "./terminal-emulator-runtime";
 
 vi.mock("@xterm/addon-webgl", () => ({
@@ -15,6 +16,14 @@ interface TerminalSize {
   cols: number;
 }
 
+interface TerminalKeyRecord {
+  key: string;
+  ctrl: boolean;
+  shift: boolean;
+  alt: boolean;
+  meta: boolean;
+}
+
 type BrowserTerminal = TerminalSize & {
   refresh: (start: number, end: number) => void;
   reset: () => void;
@@ -26,6 +35,8 @@ interface MountedTerminal {
   runtime: TerminalEmulatorRuntime;
   inputs: string[];
   sizes: TerminalSize[];
+  terminalKeys: TerminalKeyRecord[];
+  inputModeChanges: TerminalInputModeState[];
 }
 
 const mountedTerminals: MountedTerminal[] = [];
@@ -67,6 +78,8 @@ function createTerminalHost(input: { width: number; height: number }): MountedTe
 
   const sizes: TerminalSize[] = [];
   const inputs: string[] = [];
+  const terminalKeys: TerminalKeyRecord[] = [];
+  const inputModeChanges: TerminalInputModeState[] = [];
   const runtime = new TerminalEmulatorRuntime();
   runtime.setCallbacks({
     callbacks: {
@@ -76,6 +89,12 @@ function createTerminalHost(input: { width: number; height: number }): MountedTe
       onResize: (size) => {
         sizes.push(size);
       },
+      onTerminalKey: (key) => {
+        terminalKeys.push(key);
+      },
+      onInputModeChange: (state) => {
+        inputModeChanges.push(state);
+      },
     },
   });
   runtime.mount({
@@ -89,7 +108,7 @@ function createTerminalHost(input: { width: number; height: number }): MountedTe
     },
   });
 
-  const mounted = { host, root, runtime, inputs, sizes };
+  const mounted = { host, root, runtime, inputs, sizes, terminalKeys, inputModeChanges };
   mountedTerminals.push(mounted);
   return mounted;
 }
@@ -110,6 +129,32 @@ function getBrowserTerminal(): BrowserTerminal {
   return terminal;
 }
 
+function dispatchTerminalKey(input: {
+  host: HTMLElement;
+  key: string;
+  shiftKey?: boolean;
+  ctrlKey?: boolean;
+  altKey?: boolean;
+  metaKey?: boolean;
+}): boolean {
+  const textarea = input.host.querySelector<HTMLTextAreaElement>("textarea");
+  if (!textarea) {
+    throw new Error("Expected xterm textarea to be mounted");
+  }
+  textarea.focus();
+  return textarea.dispatchEvent(
+    new KeyboardEvent("keydown", {
+      key: input.key,
+      shiftKey: input.shiftKey ?? false,
+      ctrlKey: input.ctrlKey ?? false,
+      altKey: input.altKey ?? false,
+      metaKey: input.metaKey ?? false,
+      bubbles: true,
+      cancelable: true,
+    }),
+  );
+}
+
 afterEach(() => {
   for (const mounted of mountedTerminals.splice(0)) {
     mounted.runtime.unmount();
@@ -162,6 +207,73 @@ describe("terminal emulator runtime in a real browser", () => {
     expect(refreshCalls.at(-1)).toEqual([0, terminal.rows - 1]);
   });
 
+  it("intercepts Shift+Enter only after enhanced terminal input mode is active", async () => {
+    await page.viewport(900, 600);
+    const mounted = createTerminalHost({ width: 720, height: 360 });
+
+    await waitFor({ predicate: () => mounted.sizes.length > 0 });
+
+    dispatchTerminalKey({
+      host: mounted.host,
+      key: "Enter",
+      shiftKey: true,
+    });
+    await nextFrame();
+
+    expect(mounted.terminalKeys).toEqual([]);
+
+    mounted.runtime.write({ text: "\x1b[>7u" });
+    await waitFor({
+      predicate: () =>
+        mounted.inputModeChanges.some(
+          (state) => state.kittyKeyboardFlags === 7 && !state.win32InputMode,
+        ),
+    });
+
+    dispatchTerminalKey({
+      host: mounted.host,
+      key: "Enter",
+      shiftKey: true,
+    });
+    await nextFrame();
+
+    expect(mounted.terminalKeys).toEqual([
+      {
+        key: "Enter",
+        ctrl: false,
+        shift: true,
+        alt: false,
+        meta: false,
+      },
+    ]);
+
+    mounted.terminalKeys.length = 0;
+    mounted.runtime.write({ text: "\x1b[=0;0u\x1b[?9001h" });
+    await waitFor({
+      predicate: () =>
+        mounted.inputModeChanges.some(
+          (state) => state.kittyKeyboardFlags === 0 && state.win32InputMode,
+        ),
+    });
+
+    dispatchTerminalKey({
+      host: mounted.host,
+      key: "Enter",
+      shiftKey: true,
+    });
+    await nextFrame();
+
+    expect(mounted.terminalKeys).toEqual([
+      {
+        key: "Enter",
+        ctrl: false,
+        shift: true,
+        alt: false,
+        meta: false,
+      },
+    ]);
+  });
+
   it.each([
     { name: "DA1", bytes: "\x1b[c" },
     { name: "DA1-zero", bytes: "\x1b[0c" },

packages/app/src/terminal/runtime/terminal-emulator-runtime.test.ts

@@ -176,6 +176,38 @@ describe("terminal-emulator-runtime", () => {
     expect(onCommitted).toHaveBeenCalledTimes(1);
   });
 
+  it("reports input mode changes from terminal output and resets them on snapshots", () => {
+    const { runtime, writeCallbacks } = createRuntimeWithTerminal();
+    const inputModeChanges: Array<{ kittyKeyboardFlags: number; win32InputMode: boolean }> = [];
+    runtime.setCallbacks({
+      callbacks: {
+        onInputModeChange: (state) => {
+          inputModeChanges.push(state);
+        },
+      },
+    });
+
+    runtime.write({ text: "\x1b[>7u" });
+    runtime.renderSnapshot({
+      state: {
+        rows: 2,
+        cols: 8,
+        scrollback: [],
+        grid: [[{ char: "$" }, { char: " " }]],
+        cursor: {
+          row: 0,
+          col: 2,
+        },
+      },
+    });
+    writeCallbacks[0]?.();
+
+    expect(inputModeChanges).toEqual([
+      { kittyKeyboardFlags: 7, win32InputMode: false },
+      { kittyKeyboardFlags: 0, win32InputMode: false },
+    ]);
+  });
+
   it("ignores stale duplicate write callbacks from a previous operation", () => {
     const { runtime, writeCallbacks } = createRuntimeWithTerminal();
     const committed: string[] = [];

packages/app/src/terminal/runtime/terminal-emulator-runtime.ts

@@ -8,6 +8,11 @@ import { WebglAddon } from "@xterm/addon-webgl";
 import { LigaturesAddon } from "@xterm/addon-ligatures/lib/addon-ligatures.mjs";
 import { Terminal, type ITheme } from "@xterm/xterm";
 import type { TerminalState } from "@server/shared/messages";
+import {
+  type TerminalInputModeState,
+  TerminalInputModeTracker,
+  terminalInputModeStatesEqual,
+} from "@server/shared/terminal-input-mode";
 import {
   type PendingTerminalModifiers,
   isTerminalModifierDomKey,
@@ -37,6 +42,7 @@ export interface TerminalEmulatorRuntimeCallbacks {
   }) => Promise<void> | void;
   onPendingModifiersConsumed?: () => Promise<void> | void;
   onOpenExternalUrl?: (url: string) => Promise<void> | void;
+  onInputModeChange?: (state: TerminalInputModeState) => Promise<void> | void;
 }
 
 interface TerminalEmulatorRuntimeDisposables {
@@ -125,6 +131,8 @@ export class TerminalEmulatorRuntime {
   private inFlightOutputOperation: TerminalOutputOperation | null = null;
   private inFlightOutputOperationTimeout: ReturnType<typeof setTimeout> | null = null;
   private suppressInput = false;
+  private readonly inputModeTracker = new TerminalInputModeTracker();
+  private lastInputModeState: TerminalInputModeState = this.inputModeTracker.getState();
 
   private handleVisibilityRestore = (): void => {
     if (typeof document !== "undefined" && document.visibilityState !== "visible") {
@@ -152,6 +160,8 @@ export class TerminalEmulatorRuntime {
 
     input.host.innerHTML = "";
     this.lastSize = null;
+    this.inputModeTracker.reset();
+    this.emitInputModeChange();
 
     const terminal = new Terminal({
       allowProposedApi: true,
@@ -353,6 +363,7 @@ export class TerminalEmulatorRuntime {
           altKey: event.altKey,
           metaKey: event.metaKey,
           pendingModifiers: this.pendingModifiers,
+          enhancedInputActive: this.inputModeTracker.supportsModifiedEnter(),
         })
       ) {
         return true;
@@ -606,6 +617,8 @@ export class TerminalEmulatorRuntime {
     this.fitAndEmitResize = null;
     this.lastSize = null;
     this.suppressInput = false;
+    this.inputModeTracker.reset();
+    this.emitInputModeChange();
   }
 
   private processOutputQueue(): void {
@@ -640,12 +653,16 @@ export class TerminalEmulatorRuntime {
     };
 
     if (operation.type === "clear") {
+      this.inputModeTracker.reset();
+      this.emitInputModeChange();
       terminal.reset();
       finalizeOperation(operation);
       return;
     }
 
     if (operation.type === "snapshot") {
+      this.inputModeTracker.reset();
+      this.emitInputModeChange();
       try {
         if (
           typeof operation.cols === "number" &&
@@ -661,6 +678,12 @@ export class TerminalEmulatorRuntime {
     }
 
     const text = operation.text;
+    if (operation.type === "write") {
+      const result = this.inputModeTracker.feed(text);
+      if (result.changed) {
+        this.emitInputModeChange();
+      }
+    }
     this.inFlightOutputOperationTimeout = setTimeout(() => {
       finalizeOperation(operation);
     }, OUTPUT_OPERATION_TIMEOUT_MS);
@@ -682,6 +705,15 @@ export class TerminalEmulatorRuntime {
     this.inFlightOutputOperationTimeout = null;
   }
 
+  private emitInputModeChange(): void {
+    const state = this.inputModeTracker.getState();
+    if (terminalInputModeStatesEqual(state, this.lastInputModeState)) {
+      return;
+    }
+    this.lastInputModeState = state;
+    this.callbacks.onInputModeChange?.(state);
+  }
+
   private applyDocumentBoundsStyles(input: { root: HTMLDivElement }): () => void {
     const documentElement = document.documentElement;
     const body = document.body;

packages/app/src/utils/terminal-keys.test.ts

@@ -95,7 +95,7 @@ describe("terminal key helpers", () => {
     ).toBe(true);
   });
 
-  it("intercepts Enter with DOM shift modifier for CSI u encoding", () => {
+  it("does not intercept modified Enter before enhanced input mode is active", () => {
     expect(
       shouldInterceptDomTerminalKey({
         key: "Enter",
@@ -105,10 +105,10 @@ describe("terminal key helpers", () => {
         metaKey: false,
         pendingModifiers: { ctrl: false, shift: false, alt: false },
       }),
-    ).toBe(true);
+    ).toBe(false);
   });
 
-  it("intercepts Enter with any DOM modifier for CSI u encoding", () => {
+  it("intercepts Enter with any DOM modifier after enhanced input mode is active", () => {
     expect(
       shouldInterceptDomTerminalKey({
         key: "Enter",
@@ -117,6 +117,7 @@ describe("terminal key helpers", () => {
         altKey: false,
         metaKey: false,
         pendingModifiers: { ctrl: false, shift: false, alt: false },
+        enhancedInputActive: true,
       }),
     ).toBe(true);
     expect(
@@ -127,6 +128,7 @@ describe("terminal key helpers", () => {
         altKey: true,
         metaKey: false,
         pendingModifiers: { ctrl: false, shift: false, alt: false },
+        enhancedInputActive: true,
       }),
     ).toBe(true);
     expect(
@@ -137,6 +139,7 @@ describe("terminal key helpers", () => {
         altKey: false,
         metaKey: true,
         pendingModifiers: { ctrl: false, shift: false, alt: false },
+        enhancedInputActive: true,
       }),
     ).toBe(true);
   });

packages/app/src/utils/terminal-keys.ts

@@ -89,15 +89,13 @@ export function shouldInterceptDomTerminalKey(args: {
   altKey: boolean;
   metaKey: boolean;
   pendingModifiers: PendingTerminalModifiers;
+  enhancedInputActive?: boolean;
 }): boolean {
   if (hasPendingTerminalModifiers(args.pendingModifiers)) {
     return true;
   }
-  // xterm.js sends plain \r for Enter regardless of modifiers.
-  // Intercept modified Enter so it gets CSI u encoding (Kitty keyboard protocol),
-  // which Claude Code and other TUI apps use for Shift+Enter newlines.
   if (args.key === "Enter" && (args.shiftKey || args.ctrlKey || args.altKey || args.metaKey)) {
-    return true;
+    return Boolean(args.enhancedInputActive);
   }
   return false;
 }

packages/server/src/server/daemon-e2e/terminal.e2e.test.ts

@@ -457,6 +457,29 @@ function sendRawTerminalInput(ws: WebSocket, slot: number, data: string): void {
   );
 }
 
+function createInputModeProbeOptions(): { command: string; args: string[] } {
+  return {
+    command: process.execPath,
+    args: [
+      "-e",
+      `
+process.stdin.setRawMode?.(true);
+process.stdin.resume();
+process.stdin.on("data", (chunk) => {
+  const text = chunk.toString("utf8");
+  if (text.includes("e")) {
+    process.stdout.write("\\x1b[>7uKITTY\\n");
+  }
+  if (text.includes("w")) {
+    process.stdout.write("\\x1b[?9001hWIN32\\n");
+  }
+});
+setInterval(() => {}, 1000);
+`,
+    ],
+  };
+}
+
 async function repeatRawTerminalInput(input: {
   ws: WebSocket;
   slot: number;
@@ -945,6 +968,84 @@ test("disconnect and reconnect both receive the current snapshot", async () => {
   rmSync(cwd, { recursive: true, force: true });
 }, 30000);
 
+test("reconnected terminal streams replay active input modes after the snapshot", async () => {
+  const cwd = tmpCwd();
+  const created = await ctx.client.createTerminal(cwd, "input-mode-probe", undefined, {
+    ...createInputModeProbeOptions(),
+  });
+  const terminalId = created.terminal!.id;
+  const firstWs = await connectRawWebSocket(ctx.daemon.port);
+
+  try {
+    const firstSlot = await subscribeRawTerminal(firstWs, terminalId, "sub-input-mode-first");
+    await waitForRawBinaryFrame(
+      firstWs,
+      (frame) => frame.slot === firstSlot && frame.opcode === TerminalStreamOpcode.Snapshot,
+    );
+    sendRawTerminalInput(firstWs, firstSlot, "e");
+    await waitForRawBinaryFrame(
+      firstWs,
+      (frame) =>
+        frame.slot === firstSlot &&
+        frame.opcode === TerminalStreamOpcode.Output &&
+        getFrameText(frame).includes("KITTY"),
+    );
+    sendRawTerminalInput(firstWs, firstSlot, "w");
+    await waitForRawBinaryFrame(
+      firstWs,
+      (frame) =>
+        frame.slot === firstSlot &&
+        frame.opcode === TerminalStreamOpcode.Output &&
+        getFrameText(frame).includes("WIN32"),
+    );
+  } finally {
+    await closeWebSocket(firstWs);
+  }
+
+  const secondWs = await connectRawWebSocket(ctx.daemon.port);
+  try {
+    const secondSlot = await subscribeRawTerminal(secondWs, terminalId, "sub-input-mode-second");
+    await waitForRawBinaryFrame(
+      secondWs,
+      (frame) => frame.slot === secondSlot && frame.opcode === TerminalStreamOpcode.Snapshot,
+    );
+    const replay = await waitForRawBinaryFrame(
+      secondWs,
+      (frame) =>
+        frame.slot === secondSlot &&
+        frame.opcode === TerminalStreamOpcode.Output &&
+        getFrameText(frame).includes("\x1b[=7;1u"),
+    );
+
+    expect(getFrameText(replay)).toContain("\x1b[=7;1u");
+    expect(getFrameText(replay)).toContain("\x1b[?9001h");
+  } finally {
+    await closeWebSocket(secondWs);
+    rmSync(cwd, { recursive: true, force: true });
+  }
+}, 30000);
+
+test("reconnected terminal streams do not replay input modes before they are enabled", async () => {
+  const cwd = tmpCwd();
+  const created = await ctx.client.createTerminal(cwd, "input-mode-inactive-probe", undefined, {
+    ...createInputModeProbeOptions(),
+  });
+  const terminalId = created.terminal!.id;
+  const ws = await connectRawWebSocket(ctx.daemon.port);
+
+  try {
+    const slot = await subscribeRawTerminal(ws, terminalId, "sub-input-mode-inactive");
+    await waitForRawBinaryFrame(
+      ws,
+      (frame) => frame.slot === slot && frame.opcode === TerminalStreamOpcode.Snapshot,
+    );
+    await waitForNoRawBinaryFrame(ws, 300);
+  } finally {
+    await closeWebSocket(ws);
+    rmSync(cwd, { recursive: true, force: true });
+  }
+}, 30000);
+
 test("fast output to a slow websocket client falls back to a snapshot", async () => {
   const cwd = tmpCwd();
   const created = await ctx.client.createTerminal(cwd);

packages/server/src/shared/terminal-input-mode.test.ts

@@ -0,0 +1,81 @@
+import { describe, expect, it } from "vitest";
+import { TerminalInputModeTracker } from "./terminal-input-mode.js";
+
+describe("TerminalInputModeTracker", () => {
+  it("activates from a pushed Kitty keyboard mode and builds a replay preamble", () => {
+    const tracker = new TerminalInputModeTracker();
+
+    expect(tracker.feed("\x1b[>7u").changed).toBe(true);
+
+    expect(tracker.supportsModifiedEnter()).toBe(true);
+    expect(tracker.getKittyKeyboardFlags()).toBe(7);
+    expect(tracker.getPreamble()).toBe("\x1b[=7;1u");
+  });
+
+  it("tracks split terminal output chunks", () => {
+    const tracker = new TerminalInputModeTracker();
+
+    tracker.feed("\x1b[>");
+    const result = tracker.feed("1u");
+
+    expect(result.changed).toBe(true);
+    expect(tracker.getKittyKeyboardFlags()).toBe(1);
+  });
+
+  it("restores pushed Kitty keyboard modes when the foreground program pops them", () => {
+    const tracker = new TerminalInputModeTracker();
+
+    tracker.feed("\x1b[>1u");
+    tracker.feed("\x1b[>7u");
+    expect(tracker.getKittyKeyboardFlags()).toBe(7);
+
+    expect(tracker.feed("\x1b[<u").changed).toBe(true);
+    expect(tracker.getKittyKeyboardFlags()).toBe(1);
+
+    expect(tracker.feed("\x1b[<u").changed).toBe(true);
+    expect(tracker.supportsModifiedEnter()).toBe(false);
+  });
+
+  it("answers Kitty keyboard mode queries with the current flags", () => {
+    const tracker = new TerminalInputModeTracker();
+    tracker.feed("\x1b[=3;1u");
+
+    expect(tracker.feed("\x1b[?u").responses).toEqual(["\x1b[?3u"]);
+  });
+
+  it("tracks ConPTY Win32 input mode and replays it after snapshots", () => {
+    const tracker = new TerminalInputModeTracker();
+
+    expect(tracker.feed("\x1b[?9001h").changed).toBe(true);
+
+    expect(tracker.getState()).toEqual({
+      kittyKeyboardFlags: 0,
+      win32InputMode: true,
+    });
+    expect(tracker.supportsModifiedEnter()).toBe(true);
+    expect(tracker.getPreamble()).toBe("\x1b[?9001h");
+
+    expect(tracker.feed("\x1b[?9001l").changed).toBe(true);
+    expect(tracker.supportsModifiedEnter()).toBe(false);
+  });
+
+  it("keeps Kitty and Win32 input modes independent", () => {
+    const tracker = new TerminalInputModeTracker();
+
+    tracker.feed("\x1b[>7u\x1b[?9001h");
+
+    expect(tracker.getState()).toEqual({
+      kittyKeyboardFlags: 7,
+      win32InputMode: true,
+    });
+    expect(tracker.getPreamble()).toBe("\x1b[=7;1u\x1b[?9001h");
+  });
+
+  it("ignores encoded key input sequences", () => {
+    const tracker = new TerminalInputModeTracker();
+
+    tracker.feed("\x1b[13;2u");
+
+    expect(tracker.supportsModifiedEnter()).toBe(false);
+  });
+});

packages/server/src/shared/terminal-input-mode.ts

@@ -0,0 +1,194 @@
+export interface TerminalInputModeFeedResult {
+  changed: boolean;
+  responses: string[];
+}
+
+export interface TerminalInputModeState {
+  kittyKeyboardFlags: number;
+  win32InputMode: boolean;
+}
+
+export const DEFAULT_TERMINAL_INPUT_MODE_STATE: TerminalInputModeState = {
+  kittyKeyboardFlags: 0,
+  win32InputMode: false,
+};
+
+const ESC = String.fromCharCode(0x1b);
+const WIN32_INPUT_MODE = 9001;
+const CSI_INPUT_MODE_SEQUENCE = new RegExp(
+  `${ESC}\\[(?:([<>=?]?)([0-9;]*)u|\\?([0-9;]*)([hl]))`,
+  "g",
+);
+const INCOMPLETE_CSI_INPUT_MODE_SEQUENCE = new RegExp(`${ESC}\\[[<>=?]?[0-9;]*$`);
+
+function parseFirstParam(params: string): number | null {
+  const first = params.split(";")[0];
+  if (!first || !/^\d+$/.test(first)) {
+    return null;
+  }
+  return Number(first);
+}
+
+function parseSecondParam(params: string): number | null {
+  const second = params.split(";")[1];
+  if (!second || !/^\d+$/.test(second)) {
+    return null;
+  }
+  return Number(second);
+}
+
+function parsePrivateModeParams(params: string): Set<number> {
+  const modes = new Set<number>();
+  for (const param of params.split(";")) {
+    if (/^\d+$/.test(param)) {
+      modes.add(Number(param));
+    }
+  }
+  return modes;
+}
+
+export function terminalInputModeSupportsModifiedEnter(state: TerminalInputModeState): boolean {
+  return state.kittyKeyboardFlags > 0 || state.win32InputMode;
+}
+
+export function terminalInputModeStatesEqual(
+  left: TerminalInputModeState,
+  right: TerminalInputModeState,
+): boolean {
+  return (
+    left.kittyKeyboardFlags === right.kittyKeyboardFlags &&
+    left.win32InputMode === right.win32InputMode
+  );
+}
+
+export class TerminalInputModeTracker {
+  private kittyKeyboardFlags = 0;
+  private win32InputMode = false;
+  private readonly kittyKeyboardStack: number[] = [];
+  private pending = "";
+
+  feed(data: string): TerminalInputModeFeedResult {
+    if (data.length === 0) {
+      return { changed: false, responses: [] };
+    }
+
+    const text = `${this.pending}${data}`;
+    this.pending = "";
+
+    let changed = false;
+    const responses: string[] = [];
+    let consumedUntil = 0;
+
+    CSI_INPUT_MODE_SEQUENCE.lastIndex = 0;
+    for (;;) {
+      const match = CSI_INPUT_MODE_SEQUENCE.exec(text);
+      if (!match) {
+        break;
+      }
+      consumedUntil = CSI_INPUT_MODE_SEQUENCE.lastIndex;
+
+      if (match[4]) {
+        changed = this.applyPrivateModeSequence(match[3] ?? "", match[4]) || changed;
+        continue;
+      }
+
+      const result = this.applyKittyKeyboardSequence(match[1] ?? "", match[2] ?? "");
+      changed = changed || result.changed;
+      responses.push(...result.responses);
+    }
+
+    const tail = text.slice(consumedUntil);
+    const pendingStart = tail.lastIndexOf(`${ESC}[`);
+    if (pendingStart >= 0) {
+      const pending = tail.slice(pendingStart);
+      if (INCOMPLETE_CSI_INPUT_MODE_SEQUENCE.test(pending)) {
+        this.pending = pending;
+      }
+    }
+
+    return { changed, responses };
+  }
+
+  reset(): void {
+    this.kittyKeyboardFlags = 0;
+    this.win32InputMode = false;
+    this.kittyKeyboardStack.length = 0;
+    this.pending = "";
+  }
+
+  getState(): TerminalInputModeState {
+    return {
+      kittyKeyboardFlags: this.kittyKeyboardFlags,
+      win32InputMode: this.win32InputMode,
+    };
+  }
+
+  getKittyKeyboardFlags(): number {
+    return this.kittyKeyboardFlags;
+  }
+
+  supportsModifiedEnter(): boolean {
+    return terminalInputModeSupportsModifiedEnter(this.getState());
+  }
+
+  getPreamble(): string {
+    const parts: string[] = [];
+    if (this.kittyKeyboardFlags > 0) {
+      parts.push(`\x1b[=${this.kittyKeyboardFlags};1u`);
+    }
+    if (this.win32InputMode) {
+      parts.push("\x1b[?9001h");
+    }
+    return parts.join("");
+  }
+
+  private applyKittyKeyboardSequence(
+    prefix: string,
+    params: string,
+  ): { changed: boolean; responses: string[] } {
+    const previousFlags = this.kittyKeyboardFlags;
+
+    switch (prefix) {
+      case ">": {
+        this.kittyKeyboardStack.push(this.kittyKeyboardFlags);
+        this.kittyKeyboardFlags = parseFirstParam(params) ?? 1;
+        break;
+      }
+      case "=": {
+        const mode = parseSecondParam(params) ?? 1;
+        this.kittyKeyboardFlags = mode === 0 ? 0 : (parseFirstParam(params) ?? 0);
+        break;
+      }
+      case "<": {
+        const count = Math.max(1, parseFirstParam(params) ?? 1);
+        for (let index = 0; index < count; index += 1) {
+          this.kittyKeyboardFlags = this.kittyKeyboardStack.pop() ?? 0;
+        }
+        break;
+      }
+      case "?":
+        return {
+          changed: false,
+          responses: [`\x1b[?${this.kittyKeyboardFlags}u`],
+        };
+      default:
+        return { changed: false, responses: [] };
+    }
+
+    return {
+      changed: this.kittyKeyboardFlags !== previousFlags,
+      responses: [],
+    };
+  }
+
+  private applyPrivateModeSequence(params: string, final: string): boolean {
+    const modes = parsePrivateModeParams(params);
+    if (!modes.has(WIN32_INPUT_MODE)) {
+      return false;
+    }
+
+    const previous = this.win32InputMode;
+    this.win32InputMode = final === "h";
+    return this.win32InputMode !== previous;
+  }
+}

packages/server/src/shared/terminal-key-input.test.ts

@@ -19,15 +19,36 @@ describe("encodeTerminalKeyInput", () => {
     expect(encodeTerminalKeyInput({ key: "Backspace" })).toBe("\x7f");
   });
 
-  it("encodes shift+enter as kitty keyboard protocol CSI u", () => {
-    expect(encodeTerminalKeyInput({ key: "Enter", shift: true })).toBe("\x1b[13;2u");
+  it("keeps modified Enter as carriage return before enhanced input mode is active", () => {
+    expect(encodeTerminalKeyInput({ key: "Enter", shift: true })).toBe("\r");
   });
 
-  it("encodes enter with modifiers using CSI u", () => {
-    expect(encodeTerminalKeyInput({ key: "Enter", ctrl: true })).toBe("\x1b[13;5u");
-    expect(encodeTerminalKeyInput({ key: "Enter", alt: true })).toBe("\x1b[13;3u");
-    expect(encodeTerminalKeyInput({ key: "Enter", meta: true })).toBe("\x1b[13;9u");
-    expect(encodeTerminalKeyInput({ key: "Enter", shift: true, ctrl: true })).toBe("\x1b[13;6u");
+  it("encodes Enter with modifiers using CSI u after Kitty keyboard mode is active", () => {
+    const options = { inputMode: { kittyKeyboardFlags: 7, win32InputMode: false } };
+
+    expect(encodeTerminalKeyInput({ key: "Enter", shift: true }, options)).toBe("\x1b[13;2u");
+    expect(encodeTerminalKeyInput({ key: "Enter", ctrl: true }, options)).toBe("\x1b[13;5u");
+    expect(encodeTerminalKeyInput({ key: "Enter", alt: true }, options)).toBe("\x1b[13;3u");
+    expect(encodeTerminalKeyInput({ key: "Enter", meta: true }, options)).toBe("\x1b[13;9u");
+    expect(encodeTerminalKeyInput({ key: "Enter", shift: true, ctrl: true }, options)).toBe(
+      "\x1b[13;6u",
+    );
+  });
+
+  it("encodes Shift+Enter using Win32 input mode when ConPTY requests it", () => {
+    const options = { inputMode: { kittyKeyboardFlags: 0, win32InputMode: true } };
+
+    expect(encodeTerminalKeyInput({ key: "Enter", shift: true }, options)).toBe(
+      "\x1b[13;28;13;1;16;1_",
+    );
+  });
+
+  it("prefers Win32 input mode over CSI u when both modes are active", () => {
+    const options = { inputMode: { kittyKeyboardFlags: 7, win32InputMode: true } };
+
+    expect(encodeTerminalKeyInput({ key: "Enter", shift: true }, options)).toBe(
+      "\x1b[13;28;13;1;16;1_",
+    );
   });
 
   it("returns empty string for unsupported keys", () => {

packages/server/src/shared/terminal-key-input.ts

@@ -1,3 +1,5 @@
+import type { TerminalInputModeState } from "./terminal-input-mode.js";
+
 export interface TerminalKeyInput {
   key: string;
   ctrl?: boolean;
@@ -6,6 +8,14 @@ export interface TerminalKeyInput {
   meta?: boolean;
 }
 
+export interface TerminalKeyInputEncodingOptions {
+  inputMode?: TerminalInputModeState;
+}
+
+const WIN32_LEFT_ALT_PRESSED = 0x0002;
+const WIN32_LEFT_CTRL_PRESSED = 0x0008;
+const WIN32_SHIFT_PRESSED = 0x0010;
+
 function modifierParam(input: TerminalKeyInput): number {
   let value = 1;
   if (input.shift) value += 1;
@@ -15,6 +25,40 @@ function modifierParam(input: TerminalKeyInput): number {
   return value;
 }
 
+function win32ControlKeyState(input: TerminalKeyInput): number {
+  let value = 0;
+  if (input.shift) value += WIN32_SHIFT_PRESSED;
+  if (input.ctrl) value += WIN32_LEFT_CTRL_PRESSED;
+  if (input.alt) value += WIN32_LEFT_ALT_PRESSED;
+  return value;
+}
+
+function shouldUseWin32InputMode(
+  input: TerminalKeyInput,
+  options: TerminalKeyInputEncodingOptions,
+): boolean {
+  if (!options.inputMode?.win32InputMode) {
+    return false;
+  }
+  return Boolean(input.shift || input.ctrl || input.alt);
+}
+
+function shouldUseKittyKeyboardMode(
+  input: TerminalKeyInput,
+  options: TerminalKeyInputEncodingOptions,
+): boolean {
+  if ((options.inputMode?.kittyKeyboardFlags ?? 0) <= 0) {
+    return false;
+  }
+  return Boolean(input.shift || input.ctrl || input.alt || input.meta);
+}
+
+function encodeWin32EnterKeyInput(input: TerminalKeyInput): string {
+  const controlKeyState = win32ControlKeyState(input);
+  // ConPTY Win32 input mode: CSI Vk;Sc;Uc;Kd;Cs;Rc _
+  return `\x1b[13;28;13;1;${controlKeyState};1_`;
+}
+
 function applyAltLikePrefix(sequence: string, input: TerminalKeyInput): string {
   return input.alt ? `\x1b${sequence}` : sequence;
 }
@@ -144,7 +188,10 @@ function encodeNavigationKey(key: string, input: TerminalKeyInput): string | nul
   }
 }
 
-export function encodeTerminalKeyInput(input: TerminalKeyInput): string {
+export function encodeTerminalKeyInput(
+  input: TerminalKeyInput,
+  options: TerminalKeyInputEncodingOptions = {},
+): string {
   const key = input.key;
   if (!key) {
     return "";
@@ -157,7 +204,10 @@ export function encodeTerminalKeyInput(input: TerminalKeyInput): string {
   switch (key) {
     case "Enter": {
       const mod = modifierParam(input);
-      if (mod > 1) {
+      if (mod > 1 && shouldUseWin32InputMode(input, options)) {
+        return encodeWin32EnterKeyInput(input);
+      }
+      if (mod > 1 && shouldUseKittyKeyboardMode(input, options)) {
         return `\x1b[13;${mod}u`;
       }
       return "\r";

packages/server/src/terminal/terminal-session-controller.ts

@@ -681,7 +681,13 @@ export class TerminalSessionController {
       return;
     }
 
-    if (!this.terminalManager?.getTerminal(activeStream.terminalId)) {
+    const terminalManager = this.terminalManager;
+    if (!terminalManager) {
+      this.detachStream(activeStream.terminalId, { emitExit: true });
+      return;
+    }
+    const terminal = terminalManager.getTerminal(activeStream.terminalId);
+    if (!terminal) {
       this.detachStream(activeStream.terminalId, { emitExit: true });
       return;
     }
@@ -689,7 +695,7 @@ export class TerminalSessionController {
     activeStream.outputCoalescer.flush();
     activeStream.snapshotInFlight = true;
     try {
-      const snapshot = await this.terminalManager.getTerminalState(activeStream.terminalId);
+      const snapshot = await terminalManager.getTerminalState(activeStream.terminalId);
       if (this.activeStreams.get(activeStream.slot) !== activeStream) {
         return;
       }
@@ -706,6 +712,11 @@ export class TerminalSessionController {
         }),
       );
 
+      const replayPreamble = terminal.getReplayPreamble();
+      if (replayPreamble.length > 0) {
+        activeStream.outputCoalescer.handle(replayPreamble);
+      }
+
       const bufferedOutputs = activeStream.bufferedOutputs.splice(
         0,
         activeStream.bufferedOutputs.length,

packages/server/src/terminal/terminal.posix.test.ts

@@ -234,6 +234,7 @@ describe.skipIf(isPlatform("win32"))("terminal POSIX-only", () => {
     });
 
     expect(resolvedEnv.TERM).toBe("xterm-256color");
+    expect(resolvedEnv.TERM_PROGRAM).toBe("kitty");
     expect(resolvedEnv.PASEO_ZSH_ZDOTDIR).toBe("/tmp/paseo-zdotdir");
     expect(resolvedEnv.ZDOTDIR).not.toBe("/tmp/paseo-zdotdir");
     expect(existsSync(join(resolvedEnv.ZDOTDIR, ".zshenv"))).toBe(true);

packages/server/src/terminal/terminal.ts

@@ -9,6 +9,7 @@ import { fileURLToPath } from "node:url";
 import { createExternalProcessEnv } from "../server/paseo-env.js";
 import { writePrivateFileAtomicSync } from "../server/private-files.js";
 import type { TerminalCell, TerminalState } from "../shared/messages.js";
+import { TerminalInputModeTracker } from "../shared/terminal-input-mode.js";
 
 const { Terminal } = xterm;
 const require = createRequire(import.meta.url);
@@ -54,6 +55,7 @@ export interface TerminalSession {
   getSize(): { rows: number; cols: number };
   getState(): TerminalState;
   getStateSnapshot(): TerminalStateSnapshot;
+  getReplayPreamble(): string;
   getTitle(): string | undefined;
   getExitInfo(): TerminalExitInfo | null;
   kill(): void;
@@ -219,6 +221,7 @@ export function buildTerminalEnvironment(
 ): Record<string, string> {
   const baseEnv: Record<string, string> = createExternalProcessEnv(process.env, input.env, {
     TERM: "xterm-256color",
+    TERM_PROGRAM: "kitty",
   });
 
   if (basename(input.shell) !== "zsh") {
@@ -551,6 +554,7 @@ export async function createTerminal(options: CreateTerminalOptions): Promise<Te
   let pendingInput = "";
   let inputFlushImmediate: ReturnType<typeof setImmediate> | null = null;
   let stateRevision = 0;
+  const inputModeTracker = new TerminalInputModeTracker();
 
   // Create xterm.js headless terminal
   const terminal = new Terminal({
@@ -703,6 +707,7 @@ export async function createTerminal(options: CreateTerminalOptions): Promise<Te
     }
     disposed = true;
     pendingInput = "";
+    inputModeTracker.reset();
     if (inputFlushImmediate) {
       clearImmediate(inputFlushImmediate);
       inputFlushImmediate = null;
@@ -735,6 +740,10 @@ export async function createTerminal(options: CreateTerminalOptions): Promise<Te
   // Pipe PTY output to terminal emulator
   ptyProcess.onData((data) => {
     if (killed) return;
+    const inputModeUpdate = inputModeTracker.feed(data);
+    for (const response of inputModeUpdate.responses) {
+      ptyProcess.write(response);
+    }
     recentOutputText = `${recentOutputText}${data}`;
     if (recentOutputText.length > TERMINAL_EXIT_OUTPUT_CHAR_LIMIT) {
       recentOutputText = recentOutputText.slice(-TERMINAL_EXIT_OUTPUT_CHAR_LIMIT);
@@ -803,6 +812,10 @@ export async function createTerminal(options: CreateTerminalOptions): Promise<Te
     };
   }
 
+  function getReplayPreamble(): string {
+    return inputModeTracker.getPreamble();
+  }
+
   function writeInputToPty(data: string): void {
     ptyProcess.write(data);
   }
@@ -1034,6 +1047,7 @@ export async function createTerminal(options: CreateTerminalOptions): Promise<Te
     getSize,
     getState,
     getStateSnapshot,
+    getReplayPreamble,
     getTitle,
     getExitInfo,
     kill,

packages/server/src/terminal/worker-terminal-manager.ts

@@ -2,6 +2,7 @@ import { fork } from "node:child_process";
 import { fileURLToPath } from "node:url";
 import { randomUUID } from "node:crypto";
 import type { TerminalState } from "../shared/messages.js";
+import { TerminalInputModeTracker } from "../shared/terminal-input-mode.js";
 import type {
   ClientMessage,
   ServerMessage,
@@ -43,6 +44,7 @@ interface PendingRequest {
 interface WorkerTerminalRecord {
   info: WorkerTerminalInfo;
   state: TerminalState;
+  inputModeTracker: TerminalInputModeTracker;
   exitInfo: TerminalExitInfo | null;
   messageListeners: Set<(msg: ServerMessage) => void>;
   exitListeners: Set<(info: TerminalExitInfo) => void>;
@@ -169,6 +171,7 @@ export function createWorkerTerminalManager(
     const record: WorkerTerminalRecord = {
       info: cloneTerminalInfo(input.info),
       state: input.state,
+      inputModeTracker: new TerminalInputModeTracker(),
       exitInfo: null,
       messageListeners: new Set(),
       exitListeners: new Set(),
@@ -247,6 +250,9 @@ export function createWorkerTerminalManager(
           revision: 0,
         };
       },
+      getReplayPreamble(): string {
+        return record.inputModeTracker.getPreamble();
+      },
       getTitle(): string | undefined {
         return record.info.title;
       },
@@ -302,6 +308,9 @@ export function createWorkerTerminalManager(
     if (message.message.type === "snapshot") {
       record.state = message.message.state;
     }
+    if (message.message.type === "output") {
+      record.inputModeTracker.feed(message.message.data);
+    }
     for (const listener of Array.from(record.messageListeners)) {
       listener(message.message);
     }