Simplify terminal streaming protocol

2026-03-22 22:31:23 +07:00
parent 54282409bb
commit 50ea5a76fb
35 changed files with 1809 additions and 4121 deletions
@@ -1,9 +1,10 @@
 "use dom";

-import { useEffect, useMemo, useRef, useState } from "react";
+import { forwardRef, useEffect, useImperativeHandle, useMemo, useRef, useState } from "react";
 import type { DOMProps } from "expo/dom";
 import "@xterm/xterm/css/xterm.css";
 import type { ITheme } from "@xterm/xterm";
+import type { TerminalState } from "@server/shared/messages";
 import type { PendingTerminalModifiers } from "../utils/terminal-keys";
 import { TerminalEmulatorRuntime } from "../terminal/runtime/terminal-emulator-runtime";
 import { focusWithRetries } from "../utils/web-focus";
@@ -64,11 +65,7 @@ function buildXtermThemeKey(theme: ITheme): string {
 interface TerminalEmulatorProps {
  dom?: DOMProps;
  streamKey: string;
-  initialOutputText: string;
-  initialOutputChunkSequence?: number;
-  outputChunkText: string;
-  outputChunkSequence: number;
-  outputChunkReplay?: boolean;
+  initialSnapshot: TerminalState | null;
  testId?: string;
  xtermTheme?: ITheme;
  swipeGesturesEnabled?: boolean;
@@ -84,12 +81,17 @@ interface TerminalEmulatorProps {
    meta: boolean;
  }) => Promise<void> | void;
  onPendingModifiersConsumed?: () => Promise<void> | void;
-  onOutputChunkConsumed?: (sequence: number) => Promise<void> | void;
  pendingModifiers?: PendingTerminalModifiers;
  focusRequestToken?: number;
  resizeRequestToken?: number;
 }

+export type TerminalEmulatorHandle = {
+  writeOutput: (text: string) => void;
+  renderSnapshot: (state: TerminalState | null) => void;
+  clear: () => void;
+};
+
 declare global {
  interface Window {}
 }
@@ -122,13 +124,9 @@ function ensureTerminalScrollbarStyle(): void {
  document.head.appendChild(styleElement);
 }

-export default function TerminalEmulator({
+const TerminalEmulator = forwardRef<TerminalEmulatorHandle, TerminalEmulatorProps>(function TerminalEmulator({
  streamKey,
-  initialOutputText,
-  initialOutputChunkSequence = 0,
-  outputChunkText,
-  outputChunkSequence,
-  outputChunkReplay = false,
+  initialSnapshot,
  testId = "terminal-surface",
  xtermTheme = {
    background: "#0b0b0b",
@@ -142,15 +140,13 @@ export default function TerminalEmulator({
  onResize,
  onTerminalKey,
  onPendingModifiersConsumed,
-  onOutputChunkConsumed,
  pendingModifiers = { ctrl: false, shift: false, alt: false },
  focusRequestToken = 0,
  resizeRequestToken = 0,
-}: TerminalEmulatorProps) {
+}, ref) {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const hostRef = useRef<HTMLDivElement | null>(null);
  const runtimeRef = useRef<TerminalEmulatorRuntime | null>(null);
-  const appliedChunkSequenceRef = useRef(0);
  const mountedThemeRef = useRef<ITheme>(xtermTheme);
  const viewportRef = useRef<HTMLElement | null>(null);
  const dragStartOffsetRef = useRef(0);
@@ -315,17 +311,15 @@ export default function TerminalEmulator({
    runtime.mount({
      root,
      host,
-      initialOutputText,
+      initialSnapshot,
      theme: mountedThemeRef.current,
    });
-    appliedChunkSequenceRef.current = Math.max(0, Math.floor(initialOutputChunkSequence));

    return () => {
      runtime.unmount();
      if (runtimeRef.current === runtime) {
        runtimeRef.current = null;
      }
-      appliedChunkSequenceRef.current = 0;
    };
  }, [streamKey]);

@@ -344,40 +338,21 @@ export default function TerminalEmulator({
    runtimeRef.current?.setPendingModifiers({ pendingModifiers });
  }, [pendingModifiers]);

-  useEffect(() => {
-    const runtime = runtimeRef.current;
-    if (outputChunkSequence <= 0) {
-      return;
-    }
-
-    if (outputChunkSequence <= appliedChunkSequenceRef.current) {
-      onOutputChunkConsumed?.(outputChunkSequence);
-      return;
-    }
-
-    if (!runtime) {
-      onOutputChunkConsumed?.(outputChunkSequence);
-      return;
-    }
-
-    appliedChunkSequenceRef.current = outputChunkSequence;
-
-    if (outputChunkText.length === 0) {
-      runtime.clear({
-        onCommitted: () => {
-          onOutputChunkConsumed?.(outputChunkSequence);
-        },
-      });
-      return;
-    }
-    runtime.write({
-      text: outputChunkText,
-      suppressInput: outputChunkReplay,
-      onCommitted: () => {
-        onOutputChunkConsumed?.(outputChunkSequence);
+  useImperativeHandle(
+    ref,
+    () => ({
+      writeOutput: (text: string) => {
+        runtimeRef.current?.write({ text });
      },
-    });
-  }, [onOutputChunkConsumed, outputChunkReplay, outputChunkSequence, outputChunkText]);
+      renderSnapshot: (state: TerminalState | null) => {
+        runtimeRef.current?.renderSnapshot({ state });
+      },
+      clear: () => {
+        runtimeRef.current?.clear();
+      },
+    }),
+    [],
+  );

  useEffect(() => {
    if (focusRequestToken <= 0) {
@@ -694,4 +669,6 @@ export default function TerminalEmulator({
      ) : null}
    </div>
  );
-}
+});
+
+export default TerminalEmulator;
@@ -1,4 +1,4 @@
-import { useCallback, useEffect, useMemo, useRef, useState, useSyncExternalStore } from "react";
+import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import { useFocusEffect, useIsFocused } from "@react-navigation/native";
 import { ActivityIndicator, Pressable, ScrollView, Text, View } from "react-native";
 import Animated, { runOnJS, useAnimatedReaction } from "react-native-reanimated";
@@ -18,7 +18,7 @@ import {
 } from "@/terminal/runtime/terminal-stream-controller";
 import { usePanelStore } from "@/stores/panel-store";
 import { toXtermTheme } from "@/utils/to-xterm-theme";
-import TerminalEmulator from "./terminal-emulator";
+import TerminalEmulator, { type TerminalEmulatorHandle } from "./terminal-emulator";

 interface TerminalPaneProps {
  serverId: string;
@@ -26,7 +26,6 @@ interface TerminalPaneProps {
  terminalId: string;
 }

-const MAX_OUTPUT_CHARS = 200_000;
 const TERMINAL_REFIT_DELAYS_MS = [0, 48, 144, 320];

 const MODIFIER_LABELS = {
@@ -103,44 +102,8 @@ export function TerminalPane({
  const scopeKey = useMemo(() => terminalScopeKey({ serverId, cwd }), [serverId, cwd]);
  const lastReportedSizeRef = useRef<{ rows: number; cols: number } | null>(null);
  const streamControllerRef = useRef<TerminalStreamController | null>(null);
-  const workspaceTerminalSession = useMemo(
-    () =>
-      getWorkspaceTerminalSession({
-        scopeKey,
-        maxOutputChars: MAX_OUTPUT_CHARS,
-      }),
-    [scopeKey],
-  );
-  const outputSession = workspaceTerminalSession.outputSession;
-  const subscribeOutputSession = useCallback(
-    (listener: () => void) => outputSession.subscribe(listener),
-    [outputSession],
-  );
-  const getOutputSessionState = useCallback(() => outputSession.getState(), [outputSession]);
-  const outputState = useSyncExternalStore(
-    subscribeOutputSession,
-    getOutputSessionState,
-    getOutputSessionState,
-  );
-  const selectedOutputState = useMemo(() => {
-    if (outputState.selectedTerminalId === terminalId) {
-      return outputState;
-    }
-
-    return {
-      ...outputState,
-      selectedTerminalId: terminalId,
-      snapshotText: outputSession.readSnapshot({ terminalId }),
-      snapshotSequence: 0,
-      chunkText: "",
-      chunkSequence: 0,
-      chunkReplay: false,
-    };
-  }, [outputSession, outputState, terminalId]);
-  const [activeStream, setActiveStream] = useState<{
-    terminalId: string;
-    streamId: number;
-  } | null>(null);
+  const emulatorRef = useRef<TerminalEmulatorHandle | null>(null);
+  const workspaceTerminalSession = useMemo(() => getWorkspaceTerminalSession({ scopeKey }), [scopeKey]);
  const [isAttaching, setIsAttaching] = useState(false);
  const [streamError, setStreamError] = useState<string | null>(null);
  const [modifiers, setModifiers] = useState<ModifierState>(EMPTY_MODIFIERS);
@@ -150,6 +113,7 @@ export function TerminalPane({
  const pendingTerminalInputRef = useRef<PendingTerminalInput[]>([]);
  const keyboardRefitTimeoutsRef = useRef<Array<ReturnType<typeof setTimeout>>>([]);
  const lastAutoFocusKeyRef = useRef<string | null>(null);
+  const initialSnapshot = workspaceTerminalSession.snapshots.get({ terminalId });

  useEffect(() => {
    terminalIdRef.current = terminalId;
@@ -248,13 +212,16 @@ export function TerminalPane({
        return;
      }

+      workspaceTerminalSession.snapshots.clear({ terminalId: exitedTerminalId });
+      if (terminalIdRef.current === exitedTerminalId) {
+        emulatorRef.current?.clear();
+      }
      streamControllerRef.current?.handleStreamExit({
        terminalId: exitedTerminalId,
-        streamId: message.payload.streamId,
      });
      setModifiers({ ...EMPTY_MODIFIERS });
    });
-  }, [client, isConnected]);
+  }, [client, isConnected, workspaceTerminalSession.snapshots]);

  useEffect(() => {
    lastReportedSizeRef.current = null;
@@ -263,20 +230,11 @@ export function TerminalPane({
  const handleStreamControllerStatus = useCallback((status: TerminalStreamControllerStatus) => {
    setIsAttaching(status.isAttaching);
    setStreamError(status.error);
-    if (status.terminalId && typeof status.streamId === "number") {
-      setActiveStream({
-        terminalId: status.terminalId,
-        streamId: status.streamId,
-      });
-      return;
-    }
-    setActiveStream(null);
  }, []);

  useEffect(() => {
    streamControllerRef.current?.dispose();
    streamControllerRef.current = null;
-    setActiveStream(null);
    setIsAttaching(false);
    setStreamError(null);

@@ -287,12 +245,18 @@ export function TerminalPane({
    const controller = new TerminalStreamController({
      client,
      getPreferredSize: () => lastReportedSizeRef.current,
-      resumeOffsets: workspaceTerminalSession.resumeOffsets,
-      onChunk: ({ terminalId, text, replay }) => {
-        outputSession.append({ terminalId, text, replay });
+      onOutput: ({ terminalId, text }) => {
+        if (!isScreenFocused || terminalIdRef.current !== terminalId) {
+          return;
+        }
+        emulatorRef.current?.writeOutput(text);
      },
-      onReset: ({ terminalId }) => {
-        outputSession.clearTerminal({ terminalId });
+      onSnapshot: ({ terminalId, state }) => {
+        workspaceTerminalSession.snapshots.set({ terminalId, state });
+        if (!isScreenFocused || terminalIdRef.current !== terminalId) {
+          return;
+        }
+        emulatorRef.current?.renderSnapshot(state);
      },
      onStatusChange: handleStreamControllerStatus,
    });
@@ -313,26 +277,16 @@ export function TerminalPane({
    handleStreamControllerStatus,
    isConnected,
    isScreenFocused,
-    outputSession,
-    workspaceTerminalSession.resumeOffsets,
+    workspaceTerminalSession.snapshots,
  ]);

  useEffect(() => {
    pendingTerminalInputRef.current = [];
    const nextTerminalId = isScreenFocused ? terminalId : null;
-    outputSession.setSelectedTerminal({
-      terminalId: nextTerminalId,
-    });
    streamControllerRef.current?.setTerminal({
      terminalId: nextTerminalId,
    });
-  }, [isScreenFocused, outputSession, terminalId]);
-
-  const activeStreamId =
-    activeStream && activeStream.terminalId === terminalId ? activeStream.streamId : null;
-  const getCurrentActiveStreamId = useCallback(() => {
-    return streamControllerRef.current?.getActiveStreamId() ?? null;
-  }, []);
+  }, [isScreenFocused, terminalId]);

  const enqueuePendingTerminalInput = useCallback((entry: PendingTerminalInput) => {
    const queue = pendingTerminalInputRef.current;
@@ -398,8 +352,10 @@ export function TerminalPane({
  }, [dispatchTerminalInputEntry]);

  useEffect(() => {
-    flushPendingTerminalInput();
-  }, [activeStreamId, flushPendingTerminalInput]);
+    if (!isAttaching && !streamError) {
+      flushPendingTerminalInput();
+    }
+  }, [flushPendingTerminalInput, isAttaching, streamError]);

  const clearPendingModifiers = useCallback(() => {
    setModifiers({ ...EMPTY_MODIFIERS });
@@ -443,7 +399,7 @@ export function TerminalPane({
      }
      return true;
    },
-    [client, dispatchTerminalInputEntry, enqueuePendingTerminalInput, getCurrentActiveStreamId],
+    [client, dispatchTerminalInputEntry, enqueuePendingTerminalInput],
  );

  const handleTerminalData = useCallback(
@@ -496,7 +452,6 @@ export function TerminalPane({
      clearPendingModifiers,
      client,
      dispatchTerminalInputEntry,
-      getCurrentActiveStreamId,
      modifiers.alt,
      modifiers.ctrl,
      modifiers.shift,
@@ -538,13 +493,6 @@ export function TerminalPane({
    clearPendingModifiers();
  }, [clearPendingModifiers]);

-  const handleOutputChunkConsumed = useCallback(
-    (sequence: number) => {
-      outputSession.consume({ sequence });
-    },
-    [outputSession],
-  );
-
  const toggleModifier = useCallback(
    (modifier: keyof ModifierState) => {
      setModifiers((current) => ({ ...current, [modifier]: !current[modifier] }));
@@ -589,6 +537,7 @@ export function TerminalPane({
        {isScreenFocused ? (
          <View style={styles.terminalGestureContainer}>
            <TerminalEmulator
+              ref={emulatorRef}
              dom={{
                style: { flex: 1 },
                matchContents: false,
@@ -600,11 +549,7 @@ export function TerminalPane({
                contentInsetAdjustmentBehavior: "never",
              }}
              streamKey={`${scopeKey}:${terminalId}`}
-              initialOutputText={selectedOutputState.snapshotText}
-              initialOutputChunkSequence={selectedOutputState.snapshotSequence}
-              outputChunkText={selectedOutputState.chunkText}
-              outputChunkSequence={selectedOutputState.chunkSequence}
-              outputChunkReplay={selectedOutputState.chunkReplay}
+              initialSnapshot={initialSnapshot}
              testId="terminal-surface"
              xtermTheme={xtermTheme}
              swipeGesturesEnabled={swipeGesturesEnabled}
@@ -624,7 +569,6 @@ export function TerminalPane({
              onResize={handleTerminalResize}
              onTerminalKey={handleTerminalKey}
              onPendingModifiersConsumed={handlePendingModifiersConsumed}
-              onOutputChunkConsumed={handleOutputChunkConsumed}
              pendingModifiers={modifiers}
              focusRequestToken={focusRequestToken}
              resizeRequestToken={resizeRequestToken}
@@ -5,10 +5,12 @@ import { TerminalEmulatorRuntime } from "./terminal-emulator-runtime";
 type StubTerminal = {
  write: (text: string, callback?: () => void) => void;
  reset: () => void;
+  resize?: (cols: number, rows: number) => void;
  focus: () => void;
  refresh?: (start: number, end: number) => void;
  options?: { theme?: unknown };
  rows?: number;
+  cols?: number;
 };

 function createRuntimeWithTerminal(): {
@@ -35,10 +37,12 @@ function createRuntimeWithTerminal(): {
      resetCalls += 1;
      terminal.resetCalls = resetCalls;
    },
+    resize: () => {},
    focus: () => {},
    refresh: () => {},
    options: { theme: undefined },
    rows: 0,
+    cols: 0,
    resetCalls,
  };

@@ -188,12 +192,16 @@ describe("terminal-emulator-runtime", () => {
      refresh,
      options: { theme: { background: "before" } },
      rows: 12,
+      cols: 40,
    };
    (runtime as unknown as { terminal: StubTerminal }).terminal = terminal;

    runtime.setTheme({ theme: { background: "after" } as never });

-    expect(terminal.options?.theme).toEqual({ background: "after" });
+    expect(terminal.options?.theme).toEqual({
+      background: "after",
+      overviewRulerBorder: "after",
+    });
    expect(refresh).toHaveBeenCalledWith(0, 11);
  });

@@ -2,6 +2,7 @@ import { FitAddon } from "@xterm/addon-fit";
 import { Unicode11Addon } from "@xterm/addon-unicode11";
 import { WebglAddon } from "@xterm/addon-webgl";
 import { Terminal, type ITheme } from "@xterm/xterm";
+import type { TerminalState } from "@server/shared/messages";
 import {
  type PendingTerminalModifiers,
  isTerminalModifierDomKey,
@@ -10,11 +11,12 @@ import {
  normalizeTerminalTransportKey,
  shouldInterceptDomTerminalKey,
 } from "@/utils/terminal-keys";
+import { renderTerminalSnapshotToAnsi } from "./terminal-snapshot";

 export type TerminalEmulatorRuntimeMountInput = {
  root: HTMLDivElement;
  host: HTMLDivElement;
-  initialOutputText: string;
+  initialSnapshot: TerminalState | null;
  theme: ITheme;
 };

@@ -50,8 +52,10 @@ type TerminalEmulatorRuntimeDisposables = {
 };

 type TerminalOutputOperation = {
-  type: "write" | "clear";
+  type: "write" | "clear" | "snapshot";
  text: string;
+  rows?: number;
+  cols?: number;
  suppressInput?: boolean;
  onCommitted?: () => void;
 };
@@ -332,8 +336,8 @@ export class TerminalEmulatorRuntime {
      fitAndEmitResize(true);
    }, 0);

-    if (input.initialOutputText.length > 0) {
-      this.write({ text: input.initialOutputText, suppressInput: true });
+    if (input.initialSnapshot) {
+      this.renderSnapshot({ state: input.initialSnapshot });
    }

    this.processOutputQueue();
@@ -434,6 +438,22 @@ export class TerminalEmulatorRuntime {
    this.processOutputQueue();
  }

+  renderSnapshot(input: { state: TerminalState | null; onCommitted?: () => void }): void {
+    if (!input.state) {
+      this.clear(input);
+      return;
+    }
+    this.outputOperations.push({
+      type: "snapshot",
+      text: renderTerminalSnapshotToAnsi(input.state),
+      rows: input.state.rows,
+      cols: input.state.cols,
+      suppressInput: true,
+      ...(input.onCommitted ? { onCommitted: input.onCommitted } : {}),
+    });
+    this.processOutputQueue();
+  }
+
  resize(input?: { force?: boolean }): void {
    this.fitAndEmitResize?.(input?.force ?? false);
  }
@@ -523,6 +543,22 @@ export class TerminalEmulatorRuntime {
      return;
    }

+    if (operation.type === "snapshot") {
+      try {
+        if (
+          typeof operation.cols === "number" &&
+          typeof operation.rows === "number" &&
+          (terminal.cols !== operation.cols || terminal.rows !== operation.rows)
+        ) {
+          terminal.resize(operation.cols, operation.rows);
+        }
+        terminal.reset();
+      } catch {
+        finalizeOperation(operation);
+        return;
+      }
+    }
+
    const text = operation.text;
    this.inFlightOutputOperationTimeout = setTimeout(() => {
      finalizeOperation(operation);
@@ -1,141 +0,0 @@
-import { describe, expect, it, vi } from "vitest";
-
-import { TerminalOutputDeliveryQueue } from "./terminal-output-delivery-queue";
-
-describe("terminal-output-delivery-queue", () => {
-  it("retries in-flight delivery when consume is missing", () => {
-    vi.useFakeTimers();
-    const delivered: Array<{ sequence: number; text: string; replay: boolean }> = [];
-    const queue = new TerminalOutputDeliveryQueue({
-      onDeliver: (chunk) => {
-        delivered.push(chunk);
-      },
-      deliveryTimeoutMs: 100,
-    });
-
-    queue.enqueue({ sequence: 1, text: "a", replay: false });
-    queue.enqueue({ sequence: 2, text: "b", replay: false });
-
-    expect(delivered).toEqual([{ sequence: 1, text: "a", replay: false }]);
-
-    vi.advanceTimersByTime(100);
-    expect(delivered).toEqual([
-      { sequence: 1, text: "a", replay: false },
-      { sequence: 1, text: "a", replay: false },
-    ]);
-
-    queue.consume({ sequence: 1 });
-    expect(delivered).toEqual([
-      { sequence: 1, text: "a", replay: false },
-      { sequence: 1, text: "a", replay: false },
-      { sequence: 2, text: "b", replay: false },
-    ]);
-
-    vi.useRealTimers();
-  });
-
-  it("delivers first chunk immediately and blocks later chunks until consumed", () => {
-    const delivered: Array<{ sequence: number; text: string; replay: boolean }> = [];
-    const queue = new TerminalOutputDeliveryQueue({
-      onDeliver: (chunk) => {
-        delivered.push(chunk);
-      },
-    });
-
-    queue.enqueue({ sequence: 1, text: "a", replay: false });
-    queue.enqueue({ sequence: 2, text: "b", replay: false });
-    queue.enqueue({ sequence: 3, text: "c", replay: false });
-
-    expect(delivered).toEqual([{ sequence: 1, text: "a", replay: false }]);
-
-    queue.consume({ sequence: 1 });
-    expect(delivered).toEqual([
-      { sequence: 1, text: "a", replay: false },
-      { sequence: 3, text: "bc", replay: false },
-    ]);
-  });
-
-  it("ignores stale consume acknowledgements", () => {
-    const delivered = vi.fn();
-    const queue = new TerminalOutputDeliveryQueue({ onDeliver: delivered });
-
-    queue.enqueue({ sequence: 1, text: "x", replay: false });
-    queue.consume({ sequence: 99 });
-    queue.enqueue({ sequence: 2, text: "y", replay: false });
-
-    expect(delivered).toHaveBeenCalledTimes(1);
-    expect(delivered).toHaveBeenNthCalledWith(1, { sequence: 1, text: "x", replay: false });
-
-    queue.consume({ sequence: 1 });
-
-    expect(delivered).toHaveBeenCalledTimes(2);
-    expect(delivered).toHaveBeenNthCalledWith(2, { sequence: 2, text: "y", replay: false });
-  });
-
-  it("resets in-flight and pending chunks", () => {
-    const delivered: Array<{ sequence: number; text: string; replay: boolean }> = [];
-    const queue = new TerminalOutputDeliveryQueue({
-      onDeliver: (chunk) => {
-        delivered.push(chunk);
-      },
-    });
-
-    queue.enqueue({ sequence: 1, text: "hello", replay: false });
-    queue.enqueue({ sequence: 2, text: " world", replay: false });
-
-    queue.reset();
-    queue.enqueue({ sequence: 3, text: "next", replay: false });
-
-    expect(delivered).toEqual([
-      { sequence: 1, text: "hello", replay: false },
-      { sequence: 3, text: "next", replay: false },
-    ]);
-  });
-
-  it("preserves empty chunk payloads for authoritative clears", () => {
-    const delivered: Array<{ sequence: number; text: string; replay: boolean }> = [];
-    const queue = new TerminalOutputDeliveryQueue({
-      onDeliver: (chunk) => {
-        delivered.push(chunk);
-      },
-    });
-
-    queue.enqueue({ sequence: 1, text: "abc", replay: false });
-    queue.consume({ sequence: 1 });
-    queue.enqueue({ sequence: 2, text: "", replay: false });
-
-    expect(delivered).toEqual([
-      { sequence: 1, text: "abc", replay: false },
-      { sequence: 2, text: "", replay: false },
-    ]);
-  });
-
-  it("treats clear chunks as a delivery barrier and drops pending stale text", () => {
-    const delivered: Array<{ sequence: number; text: string; replay: boolean }> = [];
-    const queue = new TerminalOutputDeliveryQueue({
-      onDeliver: (chunk) => {
-        delivered.push(chunk);
-      },
-    });
-
-    queue.enqueue({ sequence: 1, text: "a", replay: false });
-    queue.enqueue({ sequence: 2, text: "b", replay: false });
-    queue.enqueue({ sequence: 3, text: "", replay: false });
-    queue.enqueue({ sequence: 4, text: "c", replay: false });
-
-    expect(delivered).toEqual([{ sequence: 1, text: "a", replay: false }]);
-
-    queue.consume({ sequence: 1 });
-    expect(delivered).toEqual([
-      { sequence: 1, text: "a", replay: false },
-      { sequence: 3, text: "", replay: false },
-    ]);
-
-    queue.consume({ sequence: 3 });
-    expect(delivered).toEqual([
-      { sequence: 1, text: "a", replay: false },
-      { sequence: 3, text: "", replay: false },
-      { sequence: 4, text: "c", replay: false },
-    ]);
-  });
-});
@@ -1,113 +0,0 @@
-export type TerminalOutputDeliveryChunk = {
-  sequence: number;
-  text: string;
-  replay: boolean;
-};
-
-export type TerminalOutputDeliveryQueueOptions = {
-  onDeliver: (chunk: TerminalOutputDeliveryChunk) => void;
-  deliveryTimeoutMs?: number;
-};
-
-const DEFAULT_DELIVERY_TIMEOUT_MS = 8_000;
-
-export class TerminalOutputDeliveryQueue {
-  private readonly pendingChunks: TerminalOutputDeliveryChunk[] = [];
-  private inFlightChunk: TerminalOutputDeliveryChunk | null = null;
-  private inFlightTimeout: ReturnType<typeof setTimeout> | null = null;
-  private lastSeenSequence = 0;
-  private readonly deliveryTimeoutMs: number;
-
-  constructor(private readonly options: TerminalOutputDeliveryQueueOptions) {
-    this.deliveryTimeoutMs = options.deliveryTimeoutMs ?? DEFAULT_DELIVERY_TIMEOUT_MS;
-  }
-
-  enqueue(chunk: TerminalOutputDeliveryChunk): void {
-    if (chunk.sequence <= 0) {
-      return;
-    }
-    if (chunk.sequence <= this.lastSeenSequence) {
-      return;
-    }
-    this.lastSeenSequence = chunk.sequence;
-
-    if (chunk.text.length === 0) {
-      this.pendingChunks.length = 0;
-      this.pendingChunks.push(chunk);
-      this.tryDeliver();
-      return;
-    }
-
-    const lastPendingChunk = this.pendingChunks[this.pendingChunks.length - 1];
-    if (
-      lastPendingChunk &&
-      lastPendingChunk.text.length > 0 &&
-      lastPendingChunk.replay === chunk.replay
-    ) {
-      lastPendingChunk.sequence = chunk.sequence;
-      lastPendingChunk.text += chunk.text;
-    } else {
-      this.pendingChunks.push(chunk);
-    }
-    this.tryDeliver();
-  }
-
-  consume(input: { sequence: number }): void {
-    if (this.inFlightChunk?.sequence !== input.sequence) {
-      return;
-    }
-
-    this.clearInFlightTimeout();
-    this.inFlightChunk = null;
-    this.tryDeliver();
-  }
-
-  reset(): void {
-    this.clearInFlightTimeout();
-    this.pendingChunks.length = 0;
-    this.inFlightChunk = null;
-    this.lastSeenSequence = 0;
-  }
-
-  private tryDeliver(): void {
-    if (this.inFlightChunk) {
-      return;
-    }
-    const nextChunk = this.pendingChunks.shift();
-    if (!nextChunk) {
-      return;
-    }
-
-    this.inFlightChunk = nextChunk;
-    this.deliverInFlightChunk();
-  }
-
-  private deliverInFlightChunk(): void {
-    const chunk = this.inFlightChunk;
-    if (!chunk) {
-      return;
-    }
-
-    this.clearInFlightTimeout();
-    this.inFlightTimeout = setTimeout(() => {
-      if (!this.inFlightChunk) {
-        return;
-      }
-      this.deliverInFlightChunk();
-    }, this.deliveryTimeoutMs);
-
-    this.options.onDeliver({
-      sequence: chunk.sequence,
-      text: chunk.text,
-      replay: chunk.replay,
-    });
-  }
-
-  private clearInFlightTimeout(): void {
-    if (!this.inFlightTimeout) {
-      return;
-    }
-    clearTimeout(this.inFlightTimeout);
-    this.inFlightTimeout = null;
-  }
-}
@@ -1,99 +0,0 @@
-import { describe, expect, it, vi } from "vitest";
-
-import { TerminalOutputPump } from "./terminal-output-pump";
-
-describe("terminal-output-pump", () => {
-  it("batches selected-terminal chunk bursts into ordered flushes", () => {
-    vi.useFakeTimers();
-    const chunks: Array<{ sequence: number; text: string; replay: boolean }> = [];
-    const pump = new TerminalOutputPump({
-      maxOutputChars: 100,
-      onSelectedOutputChunk: (chunk) => {
-        chunks.push(chunk);
-      },
-    });
-
-    pump.setSelectedTerminal({ terminalId: "term-1" });
-    pump.append({ terminalId: "term-1", text: "a", replay: false });
-    pump.append({ terminalId: "term-1", text: "b", replay: false });
-    pump.append({ terminalId: "term-1", text: "c", replay: false });
-
-    expect(chunks).toEqual([]);
-
-    vi.runOnlyPendingTimers();
-
-    expect(chunks).toEqual([{ sequence: 1, text: "abc", replay: false }]);
-
-    vi.useRealTimers();
-  });
-
-  it("keeps per-terminal snapshots and switches selected stream deterministically", () => {
-    vi.useFakeTimers();
-    const chunks: Array<{ sequence: number; text: string; replay: boolean }> = [];
-    const pump = new TerminalOutputPump({
-      maxOutputChars: 10,
-      onSelectedOutputChunk: (chunk) => {
-        chunks.push(chunk);
-      },
-    });
-
-    pump.setSelectedTerminal({ terminalId: "term-1" });
-    pump.append({ terminalId: "term-1", text: "hello", replay: false });
-    vi.runOnlyPendingTimers();
-    expect(pump.readSnapshot({ terminalId: "term-1" })).toBe("hello");
-
-    pump.append({ terminalId: "term-2", text: "world", replay: false });
-    vi.runOnlyPendingTimers();
-    expect(pump.readSnapshot({ terminalId: "term-2" })).toBe("world");
-
-    pump.setSelectedTerminal({ terminalId: "term-2" });
-    pump.append({ terminalId: "term-2", text: "!", replay: false });
-    vi.runOnlyPendingTimers();
-
-    expect(chunks).toEqual([
-      { sequence: 1, text: "hello", replay: false },
-      { sequence: 2, text: "!", replay: false },
-    ]);
-
-    vi.useRealTimers();
-  });
-
-  it("resets selected output when clearing selected terminal", () => {
-    vi.useFakeTimers();
-    const chunks: Array<{ sequence: number; text: string; replay: boolean }> = [];
-    const pump = new TerminalOutputPump({
-      maxOutputChars: 10,
-      onSelectedOutputChunk: (chunk) => {
-        chunks.push(chunk);
-      },
-    });
-
-    pump.setSelectedTerminal({ terminalId: "term-1" });
-    pump.append({ terminalId: "term-1", text: "abc", replay: false });
-    vi.runOnlyPendingTimers();
-
-    pump.clearTerminal({ terminalId: "term-1" });
-
-    expect(pump.readSnapshot({ terminalId: "term-1" })).toBe("");
-    expect(chunks).toEqual([
-      { sequence: 1, text: "abc", replay: false },
-      { sequence: 2, text: "", replay: false },
-    ]);
-
-    vi.useRealTimers();
-  });
-
-  it("prunes orphaned terminal buffers", () => {
-    const pump = new TerminalOutputPump({
-      maxOutputChars: 100,
-      onSelectedOutputChunk: () => {},
-    });
-
-    pump.append({ terminalId: "a", text: "one", replay: false });
-    pump.append({ terminalId: "b", text: "two", replay: false });
-    pump.prune({ terminalIds: ["b"] });
-
-    expect(pump.readSnapshot({ terminalId: "a" })).toBe("");
-    expect(pump.readSnapshot({ terminalId: "b" })).toBe("two");
-  });
-});
@@ -1,175 +0,0 @@
-import {
-  appendTerminalOutputBuffer,
-  createTerminalOutputBuffer,
-  readTerminalOutputBuffer,
-  type TerminalOutputBuffer,
-} from "@/utils/terminal-output-buffer";
-
-export type TerminalOutputChunk = {
-  sequence: number;
-  text: string;
-  replay: boolean;
-};
-
-export type TerminalOutputPumpOptions = {
-  maxOutputChars: number;
-  onSelectedOutputChunk: (chunk: TerminalOutputChunk) => void;
-};
-
-export type TerminalOutputPumpSetSelectedInput = {
-  terminalId: string | null;
-};
-
-export type TerminalOutputPumpAppendInput = {
-  terminalId: string;
-  text: string;
-  replay: boolean;
-};
-
-export type TerminalOutputPumpReadInput = {
-  terminalId: string | null;
-};
-
-export type TerminalOutputPumpClearInput = {
-  terminalId: string;
-};
-
-export type TerminalOutputPumpPruneInput = {
-  terminalIds: string[];
-};
-
-export class TerminalOutputPump {
-  private readonly buffersByTerminalId = new Map<string, TerminalOutputBuffer>();
-  private selectedTerminalId: string | null = null;
-  private selectedChunkSequence = 0;
-  private selectedChunkAccumulator = "";
-  private selectedChunkAccumulatorReplay: boolean | null = null;
-  private selectedChunkFlushTimer: ReturnType<typeof setTimeout> | null = null;
-
-  constructor(private readonly options: TerminalOutputPumpOptions) {}
-
-  setSelectedTerminal(input: TerminalOutputPumpSetSelectedInput): void {
-    if (this.selectedTerminalId === input.terminalId) {
-      return;
-    }
-
-    this.clearSelectedChunkFlushTimer();
-    this.selectedChunkAccumulator = "";
-    this.selectedChunkAccumulatorReplay = null;
-    this.selectedTerminalId = input.terminalId;
-  }
-
-  append(input: TerminalOutputPumpAppendInput): void {
-    if (input.text.length === 0) {
-      return;
-    }
-
-    let buffer = this.buffersByTerminalId.get(input.terminalId);
-    if (!buffer) {
-      buffer = createTerminalOutputBuffer();
-      this.buffersByTerminalId.set(input.terminalId, buffer);
-    }
-
-    appendTerminalOutputBuffer({
-      buffer,
-      text: input.text,
-      maxChars: this.options.maxOutputChars,
-    });
-
-    if (this.selectedTerminalId !== input.terminalId) {
-      return;
-    }
-
-    if (
-      this.selectedChunkAccumulator.length > 0 &&
-      typeof this.selectedChunkAccumulatorReplay === "boolean" &&
-      this.selectedChunkAccumulatorReplay !== input.replay
-    ) {
-      this.flushSelectedChunkAccumulator();
-    }
-
-    if (this.selectedChunkAccumulator.length === 0) {
-      this.selectedChunkAccumulatorReplay = input.replay;
-    }
-
-    this.selectedChunkAccumulator += input.text;
-    this.scheduleSelectedChunkFlush();
-  }
-
-  clearTerminal(input: TerminalOutputPumpClearInput): void {
-    this.buffersByTerminalId.delete(input.terminalId);
-    if (this.selectedTerminalId === input.terminalId) {
-      this.clearSelectedChunkFlushTimer();
-      this.selectedChunkAccumulator = "";
-      this.selectedChunkAccumulatorReplay = null;
-      this.emitSelectedChunk({ text: "", replay: false });
-    }
-  }
-
-  prune(input: TerminalOutputPumpPruneInput): void {
-    const terminalIdSet = new Set(input.terminalIds);
-    for (const terminalId of Array.from(this.buffersByTerminalId.keys())) {
-      if (!terminalIdSet.has(terminalId)) {
-        this.buffersByTerminalId.delete(terminalId);
-      }
-    }
-  }
-
-  readSnapshot(input: TerminalOutputPumpReadInput): string {
-    if (!input.terminalId) {
-      return "";
-    }
-    const buffer = this.buffersByTerminalId.get(input.terminalId);
-    if (!buffer) {
-      return "";
-    }
-    return readTerminalOutputBuffer({ buffer });
-  }
-
-  dispose(): void {
-    this.clearSelectedChunkFlushTimer();
-    this.selectedChunkAccumulator = "";
-    this.selectedTerminalId = null;
-    this.buffersByTerminalId.clear();
-  }
-
-  private scheduleSelectedChunkFlush(): void {
-    if (this.selectedChunkFlushTimer) {
-      return;
-    }
-
-    this.selectedChunkFlushTimer = setTimeout(() => {
-      this.selectedChunkFlushTimer = null;
-      this.flushSelectedChunkAccumulator();
-    }, 0);
-  }
-
-  private flushSelectedChunkAccumulator(): void {
-    if (this.selectedChunkAccumulator.length === 0) {
-      return;
-    }
-
-    const text = this.selectedChunkAccumulator;
-    const replay = this.selectedChunkAccumulatorReplay ?? false;
-    this.selectedChunkAccumulator = "";
-    this.selectedChunkAccumulatorReplay = null;
-    this.emitSelectedChunk({ text, replay });
-  }
-
-  private emitSelectedChunk(input: { text: string; replay: boolean }): void {
-    this.selectedChunkSequence += 1;
-    this.options.onSelectedOutputChunk({
-      sequence: this.selectedChunkSequence,
-      text: input.text,
-      replay: input.replay,
-    });
-  }
-
-  private clearSelectedChunkFlushTimer(): void {
-    if (!this.selectedChunkFlushTimer) {
-      return;
-    }
-    clearTimeout(this.selectedChunkFlushTimer);
-    this.selectedChunkFlushTimer = null;
-  }
-}
@@ -1,97 +0,0 @@
-import { describe, expect, it } from "vitest";
-
-import {
-  getTerminalOutputSession,
-  releaseTerminalOutputSession,
-  retainTerminalOutputSession,
-} from "./terminal-output-session";
-
-describe("terminal-output-session", () => {
-  async function flushAsyncWork(): Promise<void> {
-    await Promise.resolve();
-    await new Promise<void>((resolve) => {
-      setTimeout(() => resolve(), 0);
-    });
-    await Promise.resolve();
-  }
-
-  it("returns the same session instance for the same scope key", () => {
-    const a = getTerminalOutputSession({
-      scopeKey: "scope-a",
-      maxOutputChars: 1_000,
-    });
-    const b = getTerminalOutputSession({
-      scopeKey: "scope-a",
-      maxOutputChars: 50,
-    });
-
-    expect(a).toBe(b);
-  });
-
-  it("evicts a scope session when the retain count returns to zero", () => {
-    const scopeKey = "scope-retain-release";
-    const first = getTerminalOutputSession({
-      scopeKey,
-      maxOutputChars: 1_000,
-    });
-
-    retainTerminalOutputSession({ scopeKey });
-    releaseTerminalOutputSession({ scopeKey });
-
-    const second = getTerminalOutputSession({
-      scopeKey,
-      maxOutputChars: 1_000,
-    });
-
-    expect(second).not.toBe(first);
-  });
-
-  it("publishes selected terminal snapshot and chunk state via delivery/consume", async () => {
-    const session = getTerminalOutputSession({
-      scopeKey: "scope-session-state",
-      maxOutputChars: 1_000,
-    });
-
-    session.setSelectedTerminal({ terminalId: null });
-    session.setSelectedTerminal({ terminalId: "term-1" });
-
-    session.append({
-      terminalId: "term-1",
-      text: "abc",
-      replay: false,
-    });
-    await flushAsyncWork();
-
-    const stateAfterAppend = session.getState();
-    expect(stateAfterAppend.selectedTerminalId).toBe("term-1");
-    expect(stateAfterAppend.chunkSequence).toBeGreaterThan(0);
-    expect(stateAfterAppend.chunkText).toBe("abc");
-    expect(stateAfterAppend.snapshotText).toBe("abc");
-    expect(stateAfterAppend.snapshotSequence).toBe(stateAfterAppend.chunkSequence);
-
-    session.consume({ sequence: stateAfterAppend.chunkSequence });
-
-    const stateAfterConsume = session.getState();
-    expect(stateAfterConsume.snapshotText).toBe("abc");
-  });
-
-  it("keeps chunks for non-selected terminals out of selected state", async () => {
-    const session = getTerminalOutputSession({
-      scopeKey: "scope-other-terminal",
-      maxOutputChars: 1_000,
-    });
-
-    session.setSelectedTerminal({ terminalId: "term-1" });
-    session.append({
-      terminalId: "term-2",
-      text: "hidden",
-      replay: false,
-    });
-    await flushAsyncWork();
-
-    const state = session.getState();
-    expect(state.selectedTerminalId).toBe("term-1");
-    expect(state.chunkText).toBe("");
-    expect(state.snapshotText).toBe("");
-  });
-});
@@ -1,184 +0,0 @@
-import { TerminalOutputPump, type TerminalOutputChunk } from "./terminal-output-pump";
-import {
-  TerminalOutputDeliveryQueue,
-  type TerminalOutputDeliveryChunk,
-} from "./terminal-output-delivery-queue";
-
-type TerminalOutputState = {
-  selectedTerminalId: string | null;
-  snapshotText: string;
-  snapshotSequence: number;
-  chunkText: string;
-  chunkSequence: number;
-  chunkReplay: boolean;
-};
-
-const EMPTY_STATE: TerminalOutputState = {
-  selectedTerminalId: null,
-  snapshotText: "",
-  snapshotSequence: 0,
-  chunkText: "",
-  chunkSequence: 0,
-  chunkReplay: false,
-};
-
-export type TerminalOutputSessionAppendInput = {
-  terminalId: string;
-  text: string;
-  replay: boolean;
-};
-
-export type TerminalOutputSessionSetSelectedInput = {
-  terminalId: string | null;
-};
-
-export type TerminalOutputSessionPruneInput = {
-  terminalIds: string[];
-};
-
-export type TerminalOutputSessionConsumeInput = {
-  sequence: number;
-};
-
-export type TerminalOutputSessionReadSnapshotInput = {
-  terminalId: string | null;
-};
-
-export class TerminalOutputSession {
-  private readonly listeners = new Set<() => void>();
-  private readonly outputPump: TerminalOutputPump;
-  private readonly deliveryQueue: TerminalOutputDeliveryQueue;
-  private state: TerminalOutputState = EMPTY_STATE;
-
-  constructor(input: { maxOutputChars: number }) {
-    this.outputPump = new TerminalOutputPump({
-      maxOutputChars: input.maxOutputChars,
-      onSelectedOutputChunk: (chunk: TerminalOutputChunk) => {
-        this.deliveryQueue.enqueue(chunk);
-      },
-    });
-
-    this.deliveryQueue = new TerminalOutputDeliveryQueue({
-      onDeliver: (chunk: TerminalOutputDeliveryChunk) => {
-        const snapshotText = this.outputPump.readSnapshot({
-          terminalId: this.state.selectedTerminalId,
-        });
-        this.state = {
-          ...this.state,
-          snapshotText,
-          snapshotSequence: chunk.sequence,
-          chunkText: chunk.text,
-          chunkSequence: chunk.sequence,
-          chunkReplay: chunk.replay,
-        };
-        this.emit();
-      },
-    });
-  }
-
-  subscribe(listener: () => void): () => void {
-    this.listeners.add(listener);
-    return () => {
-      this.listeners.delete(listener);
-    };
-  }
-
-  getState(): TerminalOutputState {
-    return this.state;
-  }
-
-  setSelectedTerminal(input: TerminalOutputSessionSetSelectedInput): void {
-    if (this.state.selectedTerminalId === input.terminalId) {
-      return;
-    }
-
-    this.deliveryQueue.reset();
-    this.outputPump.setSelectedTerminal({ terminalId: input.terminalId });
-    const snapshotText = this.outputPump.readSnapshot({
-      terminalId: input.terminalId,
-    });
-    this.state = {
-      selectedTerminalId: input.terminalId,
-      snapshotText,
-      snapshotSequence: this.state.snapshotSequence,
-      chunkText: "",
-      chunkSequence: 0,
-      chunkReplay: false,
-    };
-    this.emit();
-  }
-
-  append(input: TerminalOutputSessionAppendInput): void {
-    this.outputPump.append(input);
-  }
-
-  readSnapshot(input: TerminalOutputSessionReadSnapshotInput): string {
-    return this.outputPump.readSnapshot(input);
-  }
-
-  clearTerminal(input: { terminalId: string }): void {
-    this.outputPump.clearTerminal(input);
-    if (this.state.selectedTerminalId !== input.terminalId) {
-      return;
-    }
-
-    this.deliveryQueue.reset();
-    this.state = {
-      ...this.state,
-      snapshotText: "",
-      chunkText: "",
-      chunkSequence: 0,
-      chunkReplay: false,
-    };
-    this.emit();
-  }
-
-  prune(input: TerminalOutputSessionPruneInput): void {
-    this.outputPump.prune(input);
-  }
-
-  consume(input: TerminalOutputSessionConsumeInput): void {
-    this.deliveryQueue.consume(input);
-  }
-
-  private emit(): void {
-    for (const listener of this.listeners) {
-      listener();
-    }
-  }
-}
-
-const sessionsByScopeKey = new Map<string, TerminalOutputSession>();
-const sessionRefCountByScopeKey = new Map<string, number>();
-
-export function getTerminalOutputSession(input: {
-  scopeKey: string;
-  maxOutputChars: number;
-}): TerminalOutputSession {
-  const existing = sessionsByScopeKey.get(input.scopeKey);
-  if (existing) {
-    return existing;
-  }
-
-  const session = new TerminalOutputSession({
-    maxOutputChars: input.maxOutputChars,
-  });
-  sessionsByScopeKey.set(input.scopeKey, session);
-  return session;
-}
-
-export function retainTerminalOutputSession(input: { scopeKey: string }): void {
-  const current = sessionRefCountByScopeKey.get(input.scopeKey) ?? 0;
-  sessionRefCountByScopeKey.set(input.scopeKey, current + 1);
-}
-
-export function releaseTerminalOutputSession(input: { scopeKey: string }): void {
-  const current = sessionRefCountByScopeKey.get(input.scopeKey) ?? 0;
-  if (current <= 1) {
-    sessionRefCountByScopeKey.delete(input.scopeKey);
-    sessionsByScopeKey.delete(input.scopeKey);
-    return;
-  }
-
-  sessionRefCountByScopeKey.set(input.scopeKey, current - 1);
-}
@@ -0,0 +1,117 @@
+import { Terminal as HeadlessTerminal } from "@xterm/headless";
+import { Terminal as ClientTerminal } from "@xterm/xterm";
+import { describe, expect, it } from "vitest";
+
+import { renderTerminalSnapshotToAnsi } from "./terminal-snapshot";
+
+type SnapshotCell = {
+  char: string;
+  fg: number | undefined;
+  bg: number | undefined;
+  fgMode?: number;
+  bgMode?: number;
+  bold?: boolean;
+  italic?: boolean;
+  underline?: boolean;
+};
+
+type SnapshotState = {
+  rows: number;
+  cols: number;
+  grid: SnapshotCell[][];
+  scrollback: SnapshotCell[][];
+  cursor: { row: number; col: number };
+};
+
+async function writeToTerminal(
+  terminal: Pick<ClientTerminal | HeadlessTerminal, "write">,
+  text: string,
+): Promise<void> {
+  await new Promise<void>((resolve) => {
+    terminal.write(text, () => resolve());
+  });
+}
+
+function extractState(terminal: ClientTerminal | HeadlessTerminal): SnapshotState {
+  const grid: SnapshotCell[][] = [];
+  const scrollback: SnapshotCell[][] = [];
+  const buffer = terminal.buffer.active;
+  const baseY = buffer.baseY;
+
+  for (let row = 0; row < baseY; row += 1) {
+    scrollback.push(extractRow(terminal, row));
+  }
+  for (let row = 0; row < terminal.rows; row += 1) {
+    grid.push(extractRow(terminal, baseY + row));
+  }
+
+  return {
+    rows: terminal.rows,
+    cols: terminal.cols,
+    grid,
+    scrollback,
+    cursor: {
+      row: buffer.cursorY,
+      col: buffer.cursorX,
+    },
+  };
+}
+
+function extractRow(terminal: ClientTerminal | HeadlessTerminal, row: number): SnapshotCell[] {
+  const cells: SnapshotCell[] = [];
+  const line = terminal.buffer.active.getLine(row);
+
+  for (let col = 0; col < terminal.cols; col += 1) {
+    const cell = line?.getCell(col);
+    if (!cell) {
+      cells.push({ char: " ", fg: undefined, bg: undefined });
+      continue;
+    }
+    const fgModeRaw = cell.getFgColorMode();
+    const bgModeRaw = cell.getBgColorMode();
+    const fgMode = fgModeRaw >> 24;
+    const bgMode = bgModeRaw >> 24;
+    cells.push({
+      char: cell.getChars() || " ",
+      fg: fgMode !== 0 ? cell.getFgColor() : undefined,
+      bg: bgMode !== 0 ? cell.getBgColor() : undefined,
+      fgMode: fgMode !== 0 ? fgMode : undefined,
+      bgMode: bgMode !== 0 ? bgMode : undefined,
+      bold: cell.isBold() !== 0,
+      italic: cell.isItalic() !== 0,
+      underline: cell.isUnderline() !== 0,
+    });
+  }
+
+  return cells;
+}
+
+describe("terminal-snapshot", () => {
+  it("replays extracted terminal state into a client xterm with matching grid, scrollback, and cursor", async () => {
+    const source = new HeadlessTerminal({
+      rows: 4,
+      cols: 12,
+      allowProposedApi: true,
+      scrollback: 100,
+    });
+
+    await writeToTerminal(source, "plain\r\n");
+    await writeToTerminal(source, "\u001b[31mred\u001b[0m\r\n");
+    await writeToTerminal(source, "\u001b[1mbold\u001b[0m\r\n");
+    await writeToTerminal(source, "cursor");
+    await writeToTerminal(source, "\u001b[2D");
+
+    const snapshot = extractState(source);
+
+    const client = new ClientTerminal({
+      rows: snapshot.rows,
+      cols: snapshot.cols,
+      allowProposedApi: true,
+      scrollback: 100,
+    });
+
+    await writeToTerminal(client, renderTerminalSnapshotToAnsi(snapshot));
+
+    expect(extractState(client)).toEqual(snapshot);
+  });
+});
@@ -0,0 +1,158 @@
+import type { TerminalCell, TerminalState } from "@server/shared/messages";
+
+type TerminalStyle = {
+  fg: number | undefined;
+  bg: number | undefined;
+  fgMode: number | undefined;
+  bgMode: number | undefined;
+  bold: boolean;
+  italic: boolean;
+  underline: boolean;
+};
+
+const DEFAULT_STYLE: TerminalStyle = {
+  fg: undefined,
+  bg: undefined,
+  fgMode: undefined,
+  bgMode: undefined,
+  bold: false,
+  italic: false,
+  underline: false,
+};
+
+export function renderTerminalSnapshotToAnsi(state: TerminalState): string {
+  const rows = [...state.scrollback, ...state.grid];
+  const lines: string[] = ["\u001b[?7l"];
+
+  for (let rowIndex = 0; rowIndex < rows.length; rowIndex += 1) {
+    const row = rows[rowIndex] ?? [];
+    lines.push(renderTerminalRow(row));
+    if (rowIndex < rows.length - 1) {
+      lines.push("\r\n");
+    }
+  }
+
+  lines.push("\u001b[0m");
+  lines.push(`\u001b[${state.cursor.row + 1};${state.cursor.col + 1}H`);
+  lines.push("\u001b[?7h");
+  return lines.join("");
+}
+
+function renderTerminalRow(row: TerminalCell[]): string {
+  const output: string[] = [];
+  const length = getTerminalRowLength(row);
+  let previousStyle = DEFAULT_STYLE;
+
+  for (let index = 0; index < length; index += 1) {
+    const cell = row[index] ?? { char: " " };
+    const nextStyle = getTerminalStyle(cell);
+    if (!terminalStylesEqual(previousStyle, nextStyle)) {
+      output.push(styleToAnsi(nextStyle));
+      previousStyle = nextStyle;
+    }
+    output.push(cell.char || " ");
+  }
+
+  if (!terminalStylesEqual(previousStyle, DEFAULT_STYLE)) {
+    output.push("\u001b[0m");
+  }
+
+  return output.join("");
+}
+
+function getTerminalRowLength(row: TerminalCell[]): number {
+  for (let index = row.length - 1; index >= 0; index -= 1) {
+    const cell = row[index];
+    if (!cell) {
+      continue;
+    }
+    if (cell.char !== " ") {
+      return index + 1;
+    }
+    if (
+      cell.fg !== undefined ||
+      cell.bg !== undefined ||
+      cell.fgMode !== undefined ||
+      cell.bgMode !== undefined ||
+      cell.bold ||
+      cell.italic ||
+      cell.underline
+    ) {
+      return index + 1;
+    }
+  }
+  return 0;
+}
+
+function getTerminalStyle(cell: TerminalCell): TerminalStyle {
+  return {
+    fg: cell.fg,
+    bg: cell.bg,
+    fgMode: cell.fgMode,
+    bgMode: cell.bgMode,
+    bold: Boolean(cell.bold),
+    italic: Boolean(cell.italic),
+    underline: Boolean(cell.underline),
+  };
+}
+
+function terminalStylesEqual(left: TerminalStyle, right: TerminalStyle): boolean {
+  return (
+    left.fg === right.fg &&
+    left.bg === right.bg &&
+    left.fgMode === right.fgMode &&
+    left.bgMode === right.bgMode &&
+    left.bold === right.bold &&
+    left.italic === right.italic &&
+    left.underline === right.underline
+  );
+}
+
+function styleToAnsi(style: TerminalStyle): string {
+  const codes = ["0"];
+
+  if (style.bold) {
+    codes.push("1");
+  }
+  if (style.italic) {
+    codes.push("3");
+  }
+  if (style.underline) {
+    codes.push("4");
+  }
+
+  if (style.fg !== undefined && style.fgMode !== undefined) {
+    codes.push(...colorToSgr(style.fgMode, style.fg, false));
+  }
+
+  if (style.bg !== undefined && style.bgMode !== undefined) {
+    codes.push(...colorToSgr(style.bgMode, style.bg, true));
+  }
+
+  return `\u001b[${codes.join(";")}m`;
+}
+
+function colorToSgr(mode: number, value: number, background: boolean): string[] {
+  if (mode === 1) {
+    if (value >= 8) {
+      return [String((background ? 100 : 90) + (value - 8))];
+    }
+    return [String((background ? 40 : 30) + value)];
+  }
+
+  if (mode === 2) {
+    return [background ? "48" : "38", "5", String(value)];
+  }
+
+  if (mode === 3) {
+    return [
+      background ? "48" : "38",
+      "2",
+      String((value >> 16) & 0xff),
+      String((value >> 8) & 0xff),
+      String(value & 0xff),
+    ];
+  }
+
+  return [];
+}
@@ -2,154 +2,118 @@ import { describe, expect, it } from "vitest";

 import {
  TerminalStreamController,
-  type TerminalStreamControllerAttachPayload,
-  type TerminalStreamControllerChunk,
  type TerminalStreamControllerClient,
-  type TerminalStreamControllerResumeOffsets,
  type TerminalStreamControllerStatus,
 } from "./terminal-stream-controller";

-type FakeStreamSubscriber = (chunk: TerminalStreamControllerChunk) => void;
+type TerminalStreamEvent =
+  | { terminalId: string; type: "output"; data: Uint8Array }
+  | {
+      terminalId: string;
+      type: "snapshot";
+      state: {
+        rows: number;
+        cols: number;
+        grid: Array<Array<{ char: string }>>;
+        scrollback: Array<Array<{ char: string }>>;
+        cursor: { row: number; col: number };
+      };
+    };

 class FakeTerminalStreamClient implements TerminalStreamControllerClient {
-  private readonly streamSubscribers = new Map<number, Set<FakeStreamSubscriber>>();
-  private readonly pendingChunksByStreamId = new Map<number, TerminalStreamControllerChunk[]>();
-  public attachCalls: Array<{
+  private readonly listeners = new Set<(event: TerminalStreamEvent) => void>();
+  public subscribeCalls: string[] = [];
+  public unsubscribeCalls: string[] = [];
+  public resizeCalls: Array<{ terminalId: string; rows: number; cols: number }> = [];
+  public nextSubscribeResponses: Array<{
    terminalId: string;
-    options?: {
-      resumeOffset?: number;
-      rows?: number;
-      cols?: number;
-    };
+    state: {
+      rows: number;
+      cols: number;
+      grid: Array<Array<{ char: string }>>;
+      scrollback: Array<Array<{ char: string }>>;
+      cursor: { row: number; col: number };
+    } | null;
+    error?: string | null;
  }> = [];
-  public detachCalls: number[] = [];
-  public nextAttachResponses: TerminalStreamControllerAttachPayload[] = [];

-  async attachTerminalStream(
-    terminalId: string,
-    options?: {
-      resumeOffset?: number;
-      rows?: number;
-      cols?: number;
-    },
-  ): Promise<TerminalStreamControllerAttachPayload> {
-    this.attachCalls.push({ terminalId, options });
-    const response = this.nextAttachResponses.shift();
+  async subscribeTerminal(terminalId: string) {
+    this.subscribeCalls.push(terminalId);
+    const response = this.nextSubscribeResponses.shift();
    if (!response) {
-      throw new Error("Missing fake attach response");
+      throw new Error("Missing fake subscribe response");
    }
    return response;
  }

-  async detachTerminalStream(streamId: number): Promise<void> {
-    this.detachCalls.push(streamId);
+  unsubscribeTerminal(terminalId: string): void {
+    this.unsubscribeCalls.push(terminalId);
  }

-  onTerminalStreamData(
-    streamId: number,
-    handler: (chunk: TerminalStreamControllerChunk) => void,
-  ): () => void {
-    const pendingChunks = this.pendingChunksByStreamId.get(streamId);
-    if (pendingChunks && pendingChunks.length > 0) {
-      for (const chunk of pendingChunks) {
-        handler(chunk);
-      }
-      this.pendingChunksByStreamId.delete(streamId);
-    }
-
-    const subscribers = this.streamSubscribers.get(streamId) ?? new Set();
-    subscribers.add(handler);
-    this.streamSubscribers.set(streamId, subscribers);
-    return () => {
-      const current = this.streamSubscribers.get(streamId);
-      current?.delete(handler);
-      if (current && current.size === 0) {
-        this.streamSubscribers.delete(streamId);
-      }
-    };
-  }
-
-  emitChunk(input: {
-    streamId: number;
-    offset?: number;
-    endOffset: number;
-    replay?: boolean;
-    data: string;
-  }): void {
-    const subscribers = this.streamSubscribers.get(input.streamId);
-    if (!subscribers || subscribers.size === 0) {
-      return;
-    }
-    const bytes = new TextEncoder().encode(input.data);
-    const chunk: TerminalStreamControllerChunk = {
-      offset: input.offset ?? input.endOffset - bytes.byteLength,
-      endOffset: input.endOffset,
-      replay: input.replay,
-      data: bytes,
-    };
-    for (const subscriber of subscribers) {
-      subscriber(chunk);
-    }
-  }
-
-  bufferChunk(input: {
-    streamId: number;
-    offset?: number;
-    endOffset: number;
-    replay?: boolean;
-    data: string;
-  }): void {
-    const chunks = this.pendingChunksByStreamId.get(input.streamId) ?? [];
-    const bytes = new TextEncoder().encode(input.data);
-    chunks.push({
-      offset: input.offset ?? input.endOffset - bytes.byteLength,
-      endOffset: input.endOffset,
-      replay: input.replay,
-      data: bytes,
+  sendTerminalInput(
+    terminalId: string,
+    message: { type: "resize"; rows: number; cols: number },
+  ): void {
+    this.resizeCalls.push({
+      terminalId,
+      rows: message.rows,
+      cols: message.cols,
    });
-    this.pendingChunksByStreamId.set(input.streamId, chunks);
+  }
+
+  onTerminalStreamEvent(handler: (event: TerminalStreamEvent) => void): () => void {
+    this.listeners.add(handler);
+    return () => {
+      this.listeners.delete(handler);
+    };
+  }
+
+  emit(event: TerminalStreamEvent): void {
+    for (const listener of this.listeners) {
+      listener(event);
+    }
  }
 }

 function createControllerHarness(input?: {
  client?: FakeTerminalStreamClient;
-  resumeOffsets?: TerminalStreamControllerResumeOffsets;
 }): {
  client: FakeTerminalStreamClient;
-  chunks: Array<{ terminalId: string; text: string }>;
+  outputs: Array<{ terminalId: string; text: string }>;
+  snapshots: Array<{ terminalId: string; text: string }>;
  statuses: TerminalStreamControllerStatus[];
-  resets: string[];
  controller: TerminalStreamController;
 } {
  const client = input?.client ?? new FakeTerminalStreamClient();
-  const chunks: Array<{ terminalId: string; text: string }> = [];
+  const outputs: Array<{ terminalId: string; text: string }> = [];
+  const snapshots: Array<{ terminalId: string; text: string }> = [];
  const statuses: TerminalStreamControllerStatus[] = [];
-  const resets: string[] = [];

  const controller = new TerminalStreamController({
    client,
    getPreferredSize: () => ({ rows: 24, cols: 80 }),
-    resumeOffsets: input?.resumeOffsets,
-    onChunk: (chunk) => {
-      chunks.push({
-        terminalId: chunk.terminalId,
-        text: chunk.text,
+    onOutput: ({ terminalId, text }) => {
+      outputs.push({ terminalId, text });
+    },
+    onSnapshot: ({ terminalId, state }) => {
+      snapshots.push({
+        terminalId,
+        text: state.grid
+          .map((row) => row.map((cell) => cell.char).join(""))
+          .join("\n"),
      });
    },
    onStatusChange: (status) => {
      statuses.push(status);
    },
-    onReset: ({ terminalId }) => {
-      resets.push(terminalId);
-    },
    waitForDelay: async () => {},
  });

  return {
    client,
-    chunks,
+    outputs,
+    snapshots,
    statuses,
-    resets,
    controller,
  };
 }
@@ -163,425 +127,122 @@ async function flushAsyncWork(): Promise<void> {
 }

 describe("terminal-stream-controller", () => {
-  it("streams burst chunks in order without dropping intermediate chunks", async () => {
+  it("subscribes to a terminal, resizes it, and forwards snapshot/output events", async () => {
    const harness = createControllerHarness();
-    harness.client.nextAttachResponses.push({
-      streamId: 7,
-      currentOffset: 0,
-      reset: false,
+    harness.client.nextSubscribeResponses.push({
+      terminalId: "term-1",
+      state: null,
      error: null,
    });

    harness.controller.setTerminal({ terminalId: "term-1" });
    await flushAsyncWork();

-    harness.client.emitChunk({
-      streamId: 7,
-      endOffset: 1,
-      data: "a",
+    harness.client.emit({
+      terminalId: "term-1",
+      type: "snapshot",
+      state: {
+        rows: 1,
+        cols: 5,
+        grid: [[{ char: "h" }, { char: "e" }, { char: "l" }, { char: "l" }, { char: "o" }]],
+        scrollback: [],
+        cursor: { row: 0, col: 5 },
+      },
    });
-    harness.client.emitChunk({
-      streamId: 7,
-      endOffset: 2,
-      data: "b",
-    });
-    harness.client.emitChunk({
-      streamId: 7,
-      endOffset: 3,
-      data: "c",
+    harness.client.emit({
+      terminalId: "term-1",
+      type: "output",
+      data: new TextEncoder().encode(" world"),
    });

-    expect(harness.chunks).toEqual([
-      { terminalId: "term-1", text: "a" },
-      { terminalId: "term-1", text: "b" },
-      { terminalId: "term-1", text: "c" },
-    ]);
+    expect(harness.client.subscribeCalls).toEqual(["term-1"]);
+    expect(harness.client.resizeCalls).toEqual([{ terminalId: "term-1", rows: 24, cols: 80 }]);
+    expect(harness.snapshots).toEqual([{ terminalId: "term-1", text: "hello" }]);
+    expect(harness.outputs).toEqual([{ terminalId: "term-1", text: " world" }]);
+    expect(harness.statuses.at(-1)).toEqual({
+      terminalId: "term-1",
+      isAttaching: false,
+      error: null,
+    });
  });

-  it("retries retryable attach failures and then attaches", async () => {
+  it("retries retryable subscribe failures and then attaches", async () => {
    const harness = createControllerHarness();
-    harness.client.nextAttachResponses.push({
-      streamId: null,
-      currentOffset: 0,
-      reset: false,
+    harness.client.nextSubscribeResponses.push({
+      terminalId: "term-1",
+      state: null,
      error: "network disconnected",
    });
-    harness.client.nextAttachResponses.push({
-      streamId: 9,
-      currentOffset: 5,
-      reset: false,
+    harness.client.nextSubscribeResponses.push({
+      terminalId: "term-1",
+      state: null,
      error: null,
    });

    harness.controller.setTerminal({ terminalId: "term-1" });
    await flushAsyncWork();

-    expect(harness.client.attachCalls.length).toBe(2);
-    expect(harness.client.attachCalls[1]?.options).toEqual({
-      resumeOffset: 0,
-      rows: 24,
-      cols: 80,
-    });
-    expect(harness.controller.getActiveStreamId()).toBe(9);
+    expect(harness.client.subscribeCalls).toEqual(["term-1", "term-1"]);
    expect(harness.statuses.at(-1)).toEqual({
      terminalId: "term-1",
-      streamId: 9,
      isAttaching: false,
      error: null,
    });
  });

-  it("handles stream exit by reconnecting on the same terminal", async () => {
+  it("reconnects to the selected terminal when the stream exits", async () => {
    const harness = createControllerHarness();
-    harness.client.nextAttachResponses.push({
-      streamId: 3,
-      currentOffset: 0,
-      reset: false,
+    harness.client.nextSubscribeResponses.push({
+      terminalId: "term-1",
+      state: null,
      error: null,
    });
-    harness.client.nextAttachResponses.push({
-      streamId: 4,
-      currentOffset: 2,
-      reset: false,
+    harness.client.nextSubscribeResponses.push({
+      terminalId: "term-1",
+      state: null,
      error: null,
    });

    harness.controller.setTerminal({ terminalId: "term-1" });
    await flushAsyncWork();

-    harness.client.emitChunk({
-      streamId: 3,
-      endOffset: 2,
-      data: "hi",
-    });
-    harness.controller.handleStreamExit({
-      terminalId: "term-1",
-      streamId: 3,
-    });
+    harness.controller.handleStreamExit({ terminalId: "term-1" });
    await flushAsyncWork();

-    expect(harness.client.attachCalls.length).toBe(2);
-    expect(harness.client.attachCalls[1]?.options).toEqual({
-      resumeOffset: 2,
-      rows: 24,
-      cols: 80,
-    });
-    expect(harness.controller.getActiveStreamId()).toBe(4);
+    expect(harness.client.subscribeCalls).toEqual(["term-1", "term-1"]);
    expect(harness.statuses.at(-1)).toEqual({
      terminalId: "term-1",
-      streamId: 4,
      isAttaching: false,
      error: null,
    });
  });

-  it("recovers when stream exits before initial attach completes", async () => {
+  it("unsubscribes when switching terminals and on dispose", async () => {
    const harness = createControllerHarness();
-    harness.client.nextAttachResponses.push({
-      streamId: 1,
-      currentOffset: 1200,
-      reset: false,
+    harness.client.nextSubscribeResponses.push({
+      terminalId: "term-1",
+      state: null,
      error: null,
    });
-    harness.client.nextAttachResponses.push({
-      streamId: 2,
-      currentOffset: 1200,
-      reset: false,
+    harness.client.nextSubscribeResponses.push({
+      terminalId: "term-2",
+      state: null,
      error: null,
    });

-    harness.controller.setTerminal({ terminalId: "term-attach-exit" });
-    harness.controller.handleStreamExit({
-      terminalId: "term-attach-exit",
-      streamId: 1,
-    });
+    harness.controller.setTerminal({ terminalId: "term-1" });
    await flushAsyncWork();

-    expect(harness.client.attachCalls).toHaveLength(2);
-    expect(harness.client.attachCalls[1]?.options).toEqual({
-      resumeOffset: 1200,
-      rows: 24,
-      cols: 80,
-    });
-    expect(harness.client.detachCalls).toContain(1);
-    expect(harness.controller.getActiveStreamId()).toBe(2);
-  });
+    harness.controller.setTerminal({ terminalId: "term-2" });
+    await flushAsyncWork();

-  it("emits reset callback when attach indicates output reset", async () => {
-    const harness = createControllerHarness();
-    harness.client.nextAttachResponses.push({
-      streamId: 12,
-      currentOffset: 0,
-      reset: true,
+    harness.controller.dispose();
+
+    expect(harness.client.unsubscribeCalls).toEqual(["term-1", "term-2"]);
+    expect(harness.statuses.at(-1)).toEqual({
+      terminalId: null,
+      isAttaching: false,
      error: null,
    });
-
-    harness.controller.setTerminal({ terminalId: "term-reset" });
-    await flushAsyncWork();
-
-    expect(harness.resets).toEqual(["term-reset"]);
-    expect(harness.controller.getActiveStreamId()).toBe(12);
-  });
-
-  it("delivers buffered replay chunks flushed synchronously during subscribe", async () => {
-    const harness = createControllerHarness();
-    harness.client.nextAttachResponses.push({
-      streamId: 17,
-      replayedFrom: 0,
-      currentOffset: 10,
-      reset: false,
-      error: null,
-    });
-    harness.client.bufferChunk({
-      streamId: 17,
-      offset: 0,
-      endOffset: 10,
-      replay: true,
-      data: "buffered-replay",
-    });
-
-    harness.controller.setTerminal({ terminalId: "term-buffered" });
-    await flushAsyncWork();
-
-    expect(harness.chunks).toEqual([{ terminalId: "term-buffered", text: "buffered-replay" }]);
-  });
-
-  it("clears stale selected output when bootstrap replay starts before current offset", async () => {
-    const harness = createControllerHarness();
-    harness.client.nextAttachResponses.push({
-      streamId: 61,
-      replayedFrom: 0,
-      currentOffset: 20,
-      reset: false,
-      error: null,
-    });
-
-    harness.controller.setTerminal({ terminalId: "term-bootstrap-reset" });
-    await flushAsyncWork();
-
-    expect(harness.resets).toEqual(["term-bootstrap-reset"]);
-  });
-
-  it("reattaches and replays from last contiguous offset when chunk offsets gap", async () => {
-    const harness = createControllerHarness();
-    harness.client.nextAttachResponses.push({
-      streamId: 31,
-      currentOffset: 0,
-      reset: false,
-      error: null,
-    });
-    harness.client.nextAttachResponses.push({
-      streamId: 32,
-      currentOffset: 8,
-      reset: false,
-      error: null,
-    });
-
-    harness.controller.setTerminal({ terminalId: "term-gap" });
-    await flushAsyncWork();
-
-    harness.client.emitChunk({
-      streamId: 31,
-      offset: 0,
-      endOffset: 2,
-      data: "ok",
-    });
-    harness.client.emitChunk({
-      streamId: 31,
-      offset: 4,
-      endOffset: 8,
-      data: "miss",
-    });
-    await flushAsyncWork();
-
-    expect(harness.chunks).toEqual([{ terminalId: "term-gap", text: "ok" }]);
-    expect(harness.client.detachCalls).toContain(31);
-    expect(harness.client.attachCalls.length).toBe(2);
-    expect(harness.client.attachCalls[1]?.options).toEqual({
-      resumeOffset: 2,
-      rows: 24,
-      cols: 80,
-    });
-    expect(harness.controller.getActiveStreamId()).toBe(32);
-  });
-
-  it("does not treat replay range before currentOffset as a live gap", async () => {
-    const harness = createControllerHarness();
-    harness.client.nextAttachResponses.push({
-      streamId: 41,
-      replayedFrom: 50,
-      currentOffset: 100,
-      reset: false,
-      error: null,
-    });
-    harness.client.bufferChunk({
-      streamId: 41,
-      offset: 80,
-      endOffset: 100,
-      data: "replay-tail",
-    });
-
-    harness.controller.setTerminal({ terminalId: "term-replay" });
-    await flushAsyncWork();
-
-    harness.client.emitChunk({
-      streamId: 41,
-      offset: 100,
-      endOffset: 102,
-      data: "ok",
-    });
-
-    expect(harness.client.detachCalls).toEqual([]);
-    expect(harness.client.attachCalls).toHaveLength(1);
-    expect(harness.controller.getActiveStreamId()).toBe(41);
-    expect(harness.chunks).toEqual([
-      { terminalId: "term-replay", text: "replay-tail" },
-      { terminalId: "term-replay", text: "ok" },
-    ]);
-  });
-
-  it("accepts clamped replay start after reconnect without entering a reconnect loop", async () => {
-    const harness = createControllerHarness();
-    harness.client.nextAttachResponses.push({
-      streamId: 71,
-      replayedFrom: 205,
-      currentOffset: 205,
-      reset: false,
-      error: null,
-    });
-    harness.client.nextAttachResponses.push({
-      streamId: 72,
-      replayedFrom: 396,
-      currentOffset: 978,
-      reset: true,
-      error: null,
-    });
-
-    harness.controller.setTerminal({ terminalId: "term-clamped-replay" });
-    await flushAsyncWork();
-
-    harness.client.emitChunk({
-      streamId: 71,
-      offset: 205,
-      endOffset: 299,
-      data: "first",
-    });
-    harness.client.emitChunk({
-      streamId: 71,
-      offset: 396,
-      endOffset: 493,
-      data: "gap",
-    });
-    await flushAsyncWork();
-
-    expect(harness.client.attachCalls).toHaveLength(2);
-    expect(harness.client.attachCalls[1]?.options).toEqual({
-      resumeOffset: 299,
-      rows: 24,
-      cols: 80,
-    });
-    expect(harness.controller.getActiveStreamId()).toBe(72);
-
-    harness.client.emitChunk({
-      streamId: 72,
-      replay: true,
-      offset: 396,
-      endOffset: 493,
-      data: "replay-1",
-    });
-    harness.client.emitChunk({
-      streamId: 72,
-      replay: true,
-      offset: 493,
-      endOffset: 590,
-      data: "replay-2",
-    });
-    harness.client.emitChunk({
-      streamId: 72,
-      replay: true,
-      offset: 687,
-      endOffset: 784,
-      data: "replay-3",
-    });
-    harness.client.emitChunk({
-      streamId: 72,
-      replay: false,
-      offset: 978,
-      endOffset: 1075,
-      data: "live",
-    });
-    await flushAsyncWork();
-
-    expect(harness.client.attachCalls).toHaveLength(2);
-    expect(harness.client.detachCalls.filter((streamId) => streamId === 71)).toHaveLength(1);
-    expect(harness.chunks.at(-1)).toEqual({
-      terminalId: "term-clamped-replay",
-      text: "live",
-    });
-  });
-
-  it("reuses external resume offsets across controller recreation", async () => {
-    const client = new FakeTerminalStreamClient();
-    const resumeOffsetByTerminalId = new Map<string, number>();
-    const resumeOffsets: TerminalStreamControllerResumeOffsets = {
-      get: ({ terminalId }) => resumeOffsetByTerminalId.get(terminalId),
-      set: ({ terminalId, offset }) => {
-        resumeOffsetByTerminalId.set(terminalId, offset);
-      },
-      clear: ({ terminalId }) => {
-        resumeOffsetByTerminalId.delete(terminalId);
-      },
-      prune: ({ terminalIds }) => {
-        const terminalIdSet = new Set(terminalIds);
-        for (const terminalId of Array.from(resumeOffsetByTerminalId.keys())) {
-          if (!terminalIdSet.has(terminalId)) {
-            resumeOffsetByTerminalId.delete(terminalId);
-          }
-        }
-      },
-    };
-
-    client.nextAttachResponses.push({
-      streamId: 81,
-      currentOffset: 0,
-      reset: false,
-      error: null,
-    });
-
-    const firstHarness = createControllerHarness({
-      client,
-      resumeOffsets,
-    });
-    firstHarness.controller.setTerminal({ terminalId: "term-shared-resume" });
-    await flushAsyncWork();
-
-    client.emitChunk({
-      streamId: 81,
-      offset: 0,
-      endOffset: 2,
-      data: "ok",
-    });
-    await flushAsyncWork();
-    firstHarness.controller.dispose();
-
-    client.nextAttachResponses.push({
-      streamId: 82,
-      currentOffset: 2,
-      reset: false,
-      error: null,
-    });
-
-    const secondHarness = createControllerHarness({
-      client,
-      resumeOffsets,
-    });
-    secondHarness.controller.setTerminal({ terminalId: "term-shared-resume" });
-    await flushAsyncWork();
-
-    expect(client.attachCalls.at(-1)?.options).toEqual({
-      resumeOffset: 2,
-      rows: 24,
-      cols: 80,
-    });
  });
 });
@@ -1,41 +1,28 @@
+import type { TerminalState } from "@server/shared/messages";
 import {
  getTerminalAttachRetryDelayMs,
-  getTerminalResumeOffset,
  isTerminalAttachRetryableError,
-  type TerminalResumeOffsetStore,
-  updateTerminalResumeOffset,
  waitForDuration,
  withPromiseTimeout,
 } from "@/utils/terminal-attach";

-export type TerminalStreamControllerAttachPayload = {
-  streamId: number | null;
-  replayedFrom?: number;
-  currentOffset: number;
-  reset: boolean;
-  error?: string | null;
-};
-
-export type TerminalStreamControllerChunk = {
-  offset: number;
-  endOffset: number;
-  replay?: boolean;
-  data: Uint8Array;
-};
-
 export type TerminalStreamControllerClient = {
-  attachTerminalStream: (
+  subscribeTerminal: (terminalId: string) => Promise<{
+    terminalId: string;
+    state: TerminalState | null;
+    error?: string | null;
+  }>;
+  unsubscribeTerminal: (terminalId: string) => void;
+  sendTerminalInput: (
    terminalId: string,
-    options?: {
-      resumeOffset?: number;
-      rows?: number;
-      cols?: number;
-    },
-  ) => Promise<TerminalStreamControllerAttachPayload>;
-  detachTerminalStream: (streamId: number) => Promise<unknown>;
-  onTerminalStreamData: (
-    streamId: number,
-    handler: (chunk: TerminalStreamControllerChunk) => void,
+    message: { type: "resize"; rows: number; cols: number },
+  ) => void;
+  onTerminalStreamEvent: (
+    handler: (
+      event:
+        | { terminalId: string; type: "output"; data: Uint8Array }
+        | { terminalId: string; type: "snapshot"; state: TerminalState },
+    ) => void,
  ) => () => void;
 };

@@ -46,22 +33,15 @@ export type TerminalStreamControllerSize = {

 export type TerminalStreamControllerStatus = {
  terminalId: string | null;
-  streamId: number | null;
  isAttaching: boolean;
  error: string | null;
 };

-export type TerminalStreamControllerResumeOffsets = TerminalResumeOffsetStore & {
-  clear: (input: { terminalId: string }) => void;
-  prune: (input: { terminalIds: string[] }) => void;
-};
-
 export type TerminalStreamControllerOptions = {
  client: TerminalStreamControllerClient;
  getPreferredSize: () => TerminalStreamControllerSize | null;
-  resumeOffsets?: TerminalStreamControllerResumeOffsets;
-  onChunk: (input: { terminalId: string; text: string; replay: boolean }) => void;
-  onReset?: (input: { terminalId: string }) => void;
+  onOutput: (input: { terminalId: string; text: string }) => void;
+  onSnapshot: (input: { terminalId: string; state: TerminalState }) => void;
  onStatusChange?: (status: TerminalStreamControllerStatus) => void;
  maxAttachAttempts?: number;
  attachTimeoutMs?: number;
@@ -76,37 +56,40 @@ export type TerminalStreamControllerOptions = {
  getRetryDelayMs?: (input: { attempt: number }) => number;
 };

-type TerminalStreamControllerActiveStream = {
-  terminalId: string;
-  streamId: number;
-  decoder: TextDecoder;
-  nextExpectedOffset: number | null;
-  catchUpEndOffset: number | null;
-  unsubscribe: () => void;
-};
-
 const DEFAULT_ATTACH_MAX_ATTEMPTS = 4;
 const DEFAULT_ATTACH_TIMEOUT_MS = 12_000;
 const DEFAULT_RECONNECT_ERROR_MESSAGE = "Terminal stream ended. Reconnecting…";

 export class TerminalStreamController {
-  private readonly exitedStreamsWhileAttaching = new Set<number>();
-  private readonly internalResumeOffsetByTerminalId = new Map<string, number>();
+  private readonly unsubscribeStreamEvents: () => void;
+  private readonly decoder = new TextDecoder();
  private selectedTerminalId: string | null = null;
-  private activeStream: TerminalStreamControllerActiveStream | null = null;
  private attachGeneration = 0;
  private isDisposed = false;
-  private status: TerminalStreamControllerStatus = {
-    terminalId: null,
-    streamId: null,
-    isAttaching: false,
-    error: null,
-  };

-  constructor(private readonly options: TerminalStreamControllerOptions) {}
+  constructor(private readonly options: TerminalStreamControllerOptions) {
+    this.unsubscribeStreamEvents = this.options.client.onTerminalStreamEvent((event) => {
+      if (this.isDisposed || event.terminalId !== this.selectedTerminalId) {
+        return;
+      }
+      if (event.type === "snapshot") {
+        this.decoder.decode();
+        this.options.onSnapshot({
+          terminalId: event.terminalId,
+          state: event.state,
+        });
+        return;
+      }

-  getActiveStreamId(): number | null {
-    return this.activeStream?.streamId ?? null;
+      const text = this.decoder.decode(event.data, { stream: true });
+      if (text.length === 0) {
+        return;
+      }
+      this.options.onOutput({
+        terminalId: event.terminalId,
+        text,
+      });
+    });
  }

  setTerminal(input: { terminalId: string | null }): void {
@@ -115,26 +98,23 @@ export class TerminalStreamController {
    }

    const nextTerminalId = input.terminalId;
-    const previousTerminalId = this.selectedTerminalId;
-    const isSameTerminal = previousTerminalId === nextTerminalId;
-    const hasActiveStreamForSelection =
-      isSameTerminal &&
-      this.activeStream?.terminalId === nextTerminalId &&
-      typeof this.activeStream.streamId === "number";
-    if (hasActiveStreamForSelection) {
+    if (this.selectedTerminalId === nextTerminalId) {
      return;
    }

+    const previousTerminalId = this.selectedTerminalId;
    this.selectedTerminalId = nextTerminalId;
    this.attachGeneration += 1;
    const generation = this.attachGeneration;

-    void this.detachActiveStream({ shouldDetach: true });
+    this.decoder.decode();
+    if (previousTerminalId) {
+      this.options.client.unsubscribeTerminal(previousTerminalId);
+    }

    if (!nextTerminalId) {
      this.updateStatus({
        terminalId: null,
-        streamId: null,
        isAttaching: false,
        error: null,
      });
@@ -143,7 +123,6 @@ export class TerminalStreamController {

    this.updateStatus({
      terminalId: nextTerminalId,
-      streamId: null,
      isAttaching: true,
      error: null,
    });
@@ -153,53 +132,23 @@ export class TerminalStreamController {
    });
  }

-  handleStreamExit(input: { terminalId: string; streamId: number }): void {
-    if (this.isDisposed) {
+  handleStreamExit(input: { terminalId: string }): void {
+    if (this.isDisposed || this.selectedTerminalId !== input.terminalId) {
      return;
    }

-    if (this.selectedTerminalId !== input.terminalId) {
-      return;
-    }
-
-    const activeStream = this.activeStream;
-    const activeMatches =
-      Boolean(activeStream) &&
-      activeStream!.terminalId === input.terminalId &&
-      activeStream!.streamId === input.streamId;
-    if (activeMatches) {
-      this.attachGeneration += 1;
-      const generation = this.attachGeneration;
-      void this.detachActiveStream({ shouldDetach: false });
-      this.updateStatus({
-        terminalId: input.terminalId,
-        streamId: null,
-        isAttaching: true,
-        error: this.options.reconnectErrorMessage ?? DEFAULT_RECONNECT_ERROR_MESSAGE,
-      });
-      void this.attachTerminal({
-        terminalId: input.terminalId,
-        generation,
-      });
-      return;
-    }
-
-    if (this.status.isAttaching && this.status.terminalId === input.terminalId) {
-      this.exitedStreamsWhileAttaching.add(input.streamId);
-    }
-  }
-
-  pruneResumeOffsets(input: { terminalIds: string[] }): void {
-    if (this.options.resumeOffsets) {
-      this.options.resumeOffsets.prune(input);
-      return;
-    }
-    const terminalIdSet = new Set(input.terminalIds);
-    for (const terminalId of Array.from(this.internalResumeOffsetByTerminalId.keys())) {
-      if (!terminalIdSet.has(terminalId)) {
-        this.internalResumeOffsetByTerminalId.delete(terminalId);
-      }
-    }
+    this.attachGeneration += 1;
+    const generation = this.attachGeneration;
+    this.decoder.decode();
+    this.updateStatus({
+      terminalId: input.terminalId,
+      isAttaching: true,
+      error: this.options.reconnectErrorMessage ?? DEFAULT_RECONNECT_ERROR_MESSAGE,
+    });
+    void this.attachTerminal({
+      terminalId: input.terminalId,
+      generation,
+    });
  }

  dispose(): void {
@@ -208,12 +157,15 @@ export class TerminalStreamController {
    }
    this.isDisposed = true;
    this.attachGeneration += 1;
+    this.decoder.decode();
+    const selectedTerminalId = this.selectedTerminalId;
    this.selectedTerminalId = null;
-    void this.detachActiveStream({ shouldDetach: true });
-    this.internalResumeOffsetByTerminalId.clear();
+    if (selectedTerminalId) {
+      this.options.client.unsubscribeTerminal(selectedTerminalId);
+    }
+    this.unsubscribeStreamEvents();
    this.updateStatus({
      terminalId: null,
-      streamId: null,
      isAttaching: false,
      error: null,
    });
@@ -229,53 +181,27 @@ export class TerminalStreamController {
      getRetryDelayMs = getTerminalAttachRetryDelayMs,
    } = this.options;

-    let lastErrorMessage = "Unable to attach terminal stream";
+    let lastErrorMessage = "Unable to subscribe to terminal";

    for (let attempt = 0; attempt < maxAttachAttempts; attempt += 1) {
-      if (
-        !this.isAttachGenerationCurrent({
-          generation: input.generation,
-          terminalId: input.terminalId,
-        })
-      ) {
+      if (!this.isAttachGenerationCurrent(input)) {
        return;
      }

      try {
-        const preferredSize = this.options.getPreferredSize();
-        const resumeOffset = getTerminalResumeOffset({
-          terminalId: input.terminalId,
-          resumeOffsetStore: this.getResumeOffsetStore(),
-        });
-        const attachPayload = await withTimeout({
-          promise: this.options.client.attachTerminalStream(input.terminalId, {
-            ...(resumeOffset !== undefined ? { resumeOffset } : {}),
-            ...(preferredSize ? { rows: preferredSize.rows, cols: preferredSize.cols } : {}),
-          }),
+        const payload = await withTimeout({
+          promise: this.options.client.subscribeTerminal(input.terminalId),
          timeoutMs: attachTimeoutMs,
-          timeoutMessage: "Timed out attaching terminal stream",
+          timeoutMessage: "Timed out subscribing to terminal",
        });

-        updateTerminalResumeOffset({
-          terminalId: input.terminalId,
-          offset: attachPayload.currentOffset,
-          resumeOffsetStore: this.getResumeOffsetStore(),
-        });
-
-        if (
-          !this.isAttachGenerationCurrent({
-            generation: input.generation,
-            terminalId: input.terminalId,
-          })
-        ) {
-          if (typeof attachPayload.streamId === "number") {
-            void this.options.client.detachTerminalStream(attachPayload.streamId).catch(() => {});
-          }
+        if (!this.isAttachGenerationCurrent(input)) {
+          this.options.client.unsubscribeTerminal(input.terminalId);
          return;
        }

-        if (attachPayload.error || typeof attachPayload.streamId !== "number") {
-          lastErrorMessage = attachPayload.error ?? "Unable to attach terminal stream";
+        if (payload.error) {
+          lastErrorMessage = payload.error;
          const hasRemainingAttempts = attempt < maxAttachAttempts - 1;
          if (hasRemainingAttempts && isRetryableError({ message: lastErrorMessage })) {
            await waitForDelay({ durationMs: getRetryDelayMs({ attempt }) });
@@ -284,82 +210,30 @@ export class TerminalStreamController {

          this.updateStatus({
            terminalId: input.terminalId,
-            streamId: null,
            isAttaching: false,
            error: lastErrorMessage,
          });
          return;
        }

-        if (this.exitedStreamsWhileAttaching.has(attachPayload.streamId)) {
-          this.exitedStreamsWhileAttaching.delete(attachPayload.streamId);
-          void this.options.client.detachTerminalStream(attachPayload.streamId).catch(() => {});
-          this.attachGeneration += 1;
-          void this.attachTerminal({
-            terminalId: input.terminalId,
-            generation: this.attachGeneration,
+        const preferredSize = this.options.getPreferredSize();
+        if (preferredSize) {
+          this.options.client.sendTerminalInput(input.terminalId, {
+            type: "resize",
+            rows: preferredSize.rows,
+            cols: preferredSize.cols,
          });
-          return;
        }

-        if (attachPayload.reset) {
-          this.options.resumeOffsets?.clear({ terminalId: input.terminalId });
-          this.options.onReset?.({ terminalId: input.terminalId });
-        }
-
-        const decoder = new TextDecoder();
-        const streamId = attachPayload.streamId;
-        const replayedFromOffset =
-          typeof attachPayload.replayedFrom === "number"
-            ? Math.max(0, Math.floor(attachPayload.replayedFrom))
-            : null;
-        const currentOffset = Math.max(0, Math.floor(attachPayload.currentOffset));
-        const shouldResetForReplayBootstrap =
-          typeof resumeOffset !== "number" &&
-          typeof replayedFromOffset === "number" &&
-          replayedFromOffset < currentOffset;
-        if (shouldResetForReplayBootstrap) {
-          this.options.onReset?.({ terminalId: input.terminalId });
-        }
-        const startExpectedOffset =
-          replayedFromOffset ??
-          (typeof resumeOffset === "number"
-            ? Math.max(0, Math.floor(resumeOffset))
-            : currentOffset);
-        const catchUpEndOffset = currentOffset;
-
-        const activeStream: TerminalStreamControllerActiveStream = {
-          terminalId: input.terminalId,
-          streamId,
-          decoder,
-          nextExpectedOffset: startExpectedOffset,
-          catchUpEndOffset,
-          unsubscribe: () => {},
-        };
-        this.activeStream = activeStream;
-        const unsubscribe = this.options.client.onTerminalStreamData(streamId, (chunk) => {
-          this.handleChunk({
-            terminalId: input.terminalId,
-            streamId,
-            chunk,
-            decoder,
-          });
-        });
-        if (this.activeStream === activeStream) {
-          activeStream.unsubscribe = unsubscribe;
-        } else {
-          unsubscribe();
-        }
        this.updateStatus({
          terminalId: input.terminalId,
-          streamId,
          isAttaching: false,
          error: null,
        });
        return;
      } catch (error) {
        lastErrorMessage =
-          error instanceof Error ? error.message : "Unable to attach terminal stream";
+          error instanceof Error ? error.message : "Unable to subscribe to terminal";
        const hasRemainingAttempts = attempt < maxAttachAttempts - 1;
        if (hasRemainingAttempts && isRetryableError({ message: lastErrorMessage })) {
          await waitForDelay({ durationMs: getRetryDelayMs({ attempt }) });
@@ -368,7 +242,6 @@ export class TerminalStreamController {

        this.updateStatus({
          terminalId: input.terminalId,
-          streamId: null,
          isAttaching: false,
          error: lastErrorMessage,
        });
@@ -378,187 +251,19 @@ export class TerminalStreamController {

    this.updateStatus({
      terminalId: input.terminalId,
-      streamId: null,
      isAttaching: false,
      error: lastErrorMessage,
    });
  }

-  private handleChunk(input: {
-    terminalId: string;
-    streamId: number;
-    chunk: TerminalStreamControllerChunk;
-    decoder: TextDecoder;
-  }): void {
-    const activeStream = this.activeStream;
-    if (!activeStream) {
-      return;
-    }
-    if (activeStream.streamId !== input.streamId || activeStream.terminalId !== input.terminalId) {
-      return;
-    }
-
-    const chunkOffset = Number.isFinite(input.chunk.offset)
-      ? Math.max(0, Math.floor(input.chunk.offset))
-      : 0;
-    const chunkEndOffset = Number.isFinite(input.chunk.endOffset)
-      ? Math.max(0, Math.floor(input.chunk.endOffset))
-      : chunkOffset;
-    if (chunkEndOffset < chunkOffset) {
-      return;
-    }
-
-    const expectedOffset = activeStream.nextExpectedOffset;
-    if (typeof expectedOffset === "number") {
-      if (chunkEndOffset <= expectedOffset) {
-        return;
-      }
-      if (chunkOffset !== expectedOffset) {
-        const catchUpEndOffset = activeStream.catchUpEndOffset;
-        const canSkipReplayGap =
-          chunkOffset > expectedOffset &&
-          typeof catchUpEndOffset === "number" &&
-          expectedOffset < catchUpEndOffset &&
-          chunkOffset <= catchUpEndOffset;
-
-        if (canSkipReplayGap) {
-          activeStream.nextExpectedOffset = chunkOffset;
-        } else {
-          this.recoverFromStreamGap({
-            terminalId: input.terminalId,
-            streamId: input.streamId,
-            expectedOffset,
-            observedOffset: chunkOffset,
-          });
-          return;
-        }
-      }
-    }
-
-    if (
-      typeof activeStream.catchUpEndOffset === "number" &&
-      chunkEndOffset >= activeStream.catchUpEndOffset
-    ) {
-      activeStream.catchUpEndOffset = null;
-    }
-
-    activeStream.nextExpectedOffset = chunkEndOffset;
-    updateTerminalResumeOffset({
-      terminalId: input.terminalId,
-      offset: chunkEndOffset,
-      resumeOffsetStore: this.getResumeOffsetStore(),
-    });
-
-    const text = input.decoder.decode(input.chunk.data, { stream: true });
-    if (text.length === 0) {
-      return;
-    }
-    this.options.onChunk({
-      terminalId: input.terminalId,
-      text,
-      replay: Boolean(input.chunk.replay),
-    });
-  }
-
-  private recoverFromStreamGap(input: {
-    terminalId: string;
-    streamId: number;
-    expectedOffset: number;
-    observedOffset: number;
-  }): void {
-    const activeStream = this.activeStream;
-    if (!activeStream) {
-      return;
-    }
-    if (activeStream.streamId !== input.streamId || activeStream.terminalId !== input.terminalId) {
-      return;
-    }
-    if (this.selectedTerminalId !== input.terminalId) {
-      return;
-    }
-
-    updateTerminalResumeOffset({
-      terminalId: input.terminalId,
-      offset: input.expectedOffset,
-      resumeOffsetStore: this.getResumeOffsetStore(),
-    });
-
-    this.attachGeneration += 1;
-    const generation = this.attachGeneration;
-
-    void this.detachActiveStream({ shouldDetach: true });
-    this.updateStatus({
-      terminalId: input.terminalId,
-      streamId: null,
-      isAttaching: true,
-      error: this.options.reconnectErrorMessage ?? DEFAULT_RECONNECT_ERROR_MESSAGE,
-    });
-    void this.attachTerminal({
-      terminalId: input.terminalId,
-      generation,
-    });
-  }
-
-  private async detachActiveStream(input: { shouldDetach: boolean }): Promise<void> {
-    const activeStream = this.activeStream;
-    if (!activeStream) {
-      return;
-    }
-    this.activeStream = null;
-
-    try {
-      const tail = activeStream.decoder.decode();
-      if (tail.length > 0) {
-        this.options.onChunk({
-          terminalId: activeStream.terminalId,
-          text: tail,
-          replay: false,
-        });
-      }
-    } catch {
-      // no-op
-    }
-
-    try {
-      activeStream.unsubscribe();
-    } catch {
-      // no-op
-    }
-
-    if (!input.shouldDetach) {
-      return;
-    }
-
-    try {
-      await this.options.client.detachTerminalStream(activeStream.streamId);
-    } catch {
-      // no-op
-    }
-  }
-
-  private isAttachGenerationCurrent(input: { generation: number; terminalId: string }): boolean {
+  private isAttachGenerationCurrent(input: { terminalId: string; generation: number }): boolean {
    if (this.isDisposed) {
      return false;
    }
-    return (
-      this.attachGeneration === input.generation && this.selectedTerminalId === input.terminalId
-    );
+    return this.attachGeneration === input.generation && this.selectedTerminalId === input.terminalId;
  }

  private updateStatus(status: TerminalStreamControllerStatus): void {
-    this.status = status;
    this.options.onStatusChange?.(status);
  }
-
-  private getResumeOffsetStore(): TerminalResumeOffsetStore {
-    if (this.options.resumeOffsets) {
-      return this.options.resumeOffsets;
-    }
-    return {
-      get: ({ terminalId }) => this.internalResumeOffsetByTerminalId.get(terminalId),
-      set: ({ terminalId, offset }) => {
-        this.internalResumeOffsetByTerminalId.set(terminalId, offset);
-      },
-    };
-  }
 }
@@ -10,43 +10,56 @@ describe("workspace-terminal-session", () => {
  it("returns the same workspace session instance for the same scope", () => {
    const first = getWorkspaceTerminalSession({
      scopeKey: "workspace-a",
-      maxOutputChars: 1_000,
    });
    const second = getWorkspaceTerminalSession({
      scopeKey: "workspace-a",
-      maxOutputChars: 50,
    });

    expect(second).toBe(first);
  });

-  it("preserves resume offsets across repeated lookups", () => {
+  it("preserves snapshots across repeated lookups", () => {
    const first = getWorkspaceTerminalSession({
-      scopeKey: "workspace-resume",
-      maxOutputChars: 1_000,
+      scopeKey: "workspace-snapshots",
    });
-    first.resumeOffsets.set({
+    first.snapshots.set({
      terminalId: "term-1",
-      offset: 42,
+      state: {
+        rows: 1,
+        cols: 1,
+        grid: [[{ char: "A" }]],
+        scrollback: [],
+        cursor: { row: 0, col: 0 },
+      },
    });

    const second = getWorkspaceTerminalSession({
-      scopeKey: "workspace-resume",
-      maxOutputChars: 1_000,
+      scopeKey: "workspace-snapshots",
    });

-    expect(second.resumeOffsets.get({ terminalId: "term-1" })).toBe(42);
+    expect(second.snapshots.get({ terminalId: "term-1" })).toEqual({
+      rows: 1,
+      cols: 1,
+      grid: [[{ char: "A" }]],
+      scrollback: [],
+      cursor: { row: 0, col: 0 },
+    });
  });

-  it("evicts workspace terminal session state when the workspace retain count returns to zero", () => {
+  it("evicts workspace terminal session state when the retain count returns to zero", () => {
    const scopeKey = "workspace-release";
    const first = getWorkspaceTerminalSession({
      scopeKey,
-      maxOutputChars: 1_000,
    });
-    first.resumeOffsets.set({
+    first.snapshots.set({
      terminalId: "term-1",
-      offset: 128,
+      state: {
+        rows: 1,
+        cols: 1,
+        grid: [[{ char: "A" }]],
+        scrollback: [],
+        cursor: { row: 0, col: 0 },
+      },
    });

    retainWorkspaceTerminalSession({ scopeKey });
@@ -54,10 +67,9 @@ describe("workspace-terminal-session", () => {

    const second = getWorkspaceTerminalSession({
      scopeKey,
-      maxOutputChars: 1_000,
    });

    expect(second).not.toBe(first);
-    expect(second.resumeOffsets.get({ terminalId: "term-1" })).toBeUndefined();
+    expect(second.snapshots.get({ terminalId: "term-1" })).toBeNull();
  });
 });
@@ -1,85 +1,63 @@
-import {
-  getTerminalOutputSession,
-  releaseTerminalOutputSession,
-  retainTerminalOutputSession,
-  type TerminalOutputSession,
-} from "./terminal-output-session";
+import type { TerminalState } from "@server/shared/messages";

-export type WorkspaceTerminalResumeOffsets = {
-  get: (input: { terminalId: string }) => number | undefined;
-  set: (input: { terminalId: string; offset: number }) => void;
+export type WorkspaceTerminalSnapshots = {
+  get: (input: { terminalId: string }) => TerminalState | null;
+  set: (input: { terminalId: string; state: TerminalState }) => void;
  clear: (input: { terminalId: string }) => void;
  prune: (input: { terminalIds: string[] }) => void;
 };

 export type WorkspaceTerminalSession = {
  scopeKey: string;
-  outputSession: TerminalOutputSession;
-  resumeOffsets: WorkspaceTerminalResumeOffsets;
+  snapshots: WorkspaceTerminalSnapshots;
 };

 type WorkspaceTerminalSessionRecord = {
-  resumeOffsetByTerminalId: Map<string, number>;
+  snapshotByTerminalId: Map<string, TerminalState>;
  session: WorkspaceTerminalSession;
 };

 const sessionsByScopeKey = new Map<string, WorkspaceTerminalSessionRecord>();
 const refCountByScopeKey = new Map<string, number>();

-function createResumeOffsets(input: {
-  resumeOffsetByTerminalId: Map<string, number>;
-}): WorkspaceTerminalResumeOffsets {
+function createSnapshots(input: {
+  snapshotByTerminalId: Map<string, TerminalState>;
+}): WorkspaceTerminalSnapshots {
  return {
-    get: ({ terminalId }) => {
-      const offset = input.resumeOffsetByTerminalId.get(terminalId);
-      if (typeof offset !== "number" || !Number.isFinite(offset)) {
-        return undefined;
-      }
-      return Math.max(0, Math.floor(offset));
-    },
-    set: ({ terminalId, offset }) => {
-      if (!Number.isFinite(offset)) {
-        return;
-      }
-      input.resumeOffsetByTerminalId.set(terminalId, Math.max(0, Math.floor(offset)));
+    get: ({ terminalId }) => input.snapshotByTerminalId.get(terminalId) ?? null,
+    set: ({ terminalId, state }) => {
+      input.snapshotByTerminalId.set(terminalId, state);
    },
    clear: ({ terminalId }) => {
-      input.resumeOffsetByTerminalId.delete(terminalId);
+      input.snapshotByTerminalId.delete(terminalId);
    },
    prune: ({ terminalIds }) => {
      const terminalIdSet = new Set(terminalIds);
-      for (const terminalId of Array.from(input.resumeOffsetByTerminalId.keys())) {
+      for (const terminalId of Array.from(input.snapshotByTerminalId.keys())) {
        if (!terminalIdSet.has(terminalId)) {
-          input.resumeOffsetByTerminalId.delete(terminalId);
+          input.snapshotByTerminalId.delete(terminalId);
        }
      }
    },
  };
 }

-export function getWorkspaceTerminalSession(input: {
-  scopeKey: string;
-  maxOutputChars: number;
-}): WorkspaceTerminalSession {
+export function getWorkspaceTerminalSession(input: { scopeKey: string }): WorkspaceTerminalSession {
  const existing = sessionsByScopeKey.get(input.scopeKey);
  if (existing) {
    return existing.session;
  }

-  const resumeOffsetByTerminalId = new Map<string, number>();
+  const snapshotByTerminalId = new Map<string, TerminalState>();
  const session: WorkspaceTerminalSession = {
    scopeKey: input.scopeKey,
-    outputSession: getTerminalOutputSession({
-      scopeKey: input.scopeKey,
-      maxOutputChars: input.maxOutputChars,
-    }),
-    resumeOffsets: createResumeOffsets({
-      resumeOffsetByTerminalId,
+    snapshots: createSnapshots({
+      snapshotByTerminalId,
    }),
  };

  sessionsByScopeKey.set(input.scopeKey, {
-    resumeOffsetByTerminalId,
+    snapshotByTerminalId,
    session,
  });
  return session;
@@ -88,11 +66,9 @@ export function getWorkspaceTerminalSession(input: {
 export function retainWorkspaceTerminalSession(input: { scopeKey: string }): void {
  const current = refCountByScopeKey.get(input.scopeKey) ?? 0;
  refCountByScopeKey.set(input.scopeKey, current + 1);
-  retainTerminalOutputSession(input);
 }

 export function releaseWorkspaceTerminalSession(input: { scopeKey: string }): void {
-  releaseTerminalOutputSession(input);
  const current = refCountByScopeKey.get(input.scopeKey) ?? 0;
  if (current > 1) {
    refCountByScopeKey.set(input.scopeKey, current - 1);
@@ -1,10 +1,8 @@
 import { describe, expect, it } from "vitest";

 import {
-  getTerminalResumeOffset,
  getTerminalAttachRetryDelayMs,
  isTerminalAttachRetryableError,
-  updateTerminalResumeOffset,
  withPromiseTimeout,
 } from "./terminal-attach";

@@ -24,53 +22,12 @@ describe("terminal-attach", () => {
    expect(isTerminalAttachRetryableError({ message: "Network disconnected during attach" })).toBe(
      true,
    );
-    expect(isTerminalAttachRetryableError({ message: "stream ended before ack" })).toBe(true);
+    expect(isTerminalAttachRetryableError({ message: "stream ended before snapshot" })).toBe(
+      true,
+    );
    expect(isTerminalAttachRetryableError({ message: "permission denied" })).toBe(false);
  });

-  it("reads and updates resume offsets monotonically", () => {
-    const offsets = new Map<string, number>();
-    const terminalId = "term-1";
-    const resumeOffsetStore = {
-      get: ({ terminalId }: { terminalId: string }) => offsets.get(terminalId),
-      set: ({ terminalId, offset }: { terminalId: string; offset: number }) => {
-        offsets.set(terminalId, offset);
-      },
-    };
-
-    expect(
-      getTerminalResumeOffset({
-        terminalId,
-        resumeOffsetStore,
-      }),
-    ).toBeUndefined();
-
-    updateTerminalResumeOffset({
-      terminalId,
-      offset: 8,
-      resumeOffsetStore,
-    });
-    expect(
-      getTerminalResumeOffset({
-        terminalId,
-        resumeOffsetStore,
-      }),
-    ).toBe(8);
-
-    // Stale offsets must not move resume backwards.
-    updateTerminalResumeOffset({
-      terminalId,
-      offset: 3,
-      resumeOffsetStore,
-    });
-    expect(
-      getTerminalResumeOffset({
-        terminalId,
-        resumeOffsetStore,
-      }),
-    ).toBe(8);
-  });
-
  it("resolves before timeout when promise completes", async () => {
    await expect(
      withPromiseTimeout({
@@ -8,49 +8,6 @@ const TERMINAL_ATTACH_RETRYABLE_ERROR_PATTERNS = [
  "stream ended",
 ] as const;

-export type TerminalResumeOffsetStore = {
-  get: (input: { terminalId: string }) => number | undefined;
-  set: (input: { terminalId: string; offset: number }) => void;
-};
-
-export function getTerminalResumeOffset(input: {
-  terminalId: string;
-  resumeOffsetStore: TerminalResumeOffsetStore;
-}): number | undefined {
-  const offset = input.resumeOffsetStore.get({ terminalId: input.terminalId });
-  if (typeof offset !== "number" || !Number.isFinite(offset)) {
-    return undefined;
-  }
-
-  const normalizedOffset = Math.max(0, Math.floor(offset));
-  return normalizedOffset;
-}
-
-export function updateTerminalResumeOffset(input: {
-  terminalId: string;
-  offset: number;
-  resumeOffsetStore: TerminalResumeOffsetStore;
-}): void {
-  if (!Number.isFinite(input.offset)) {
-    return;
-  }
-
-  const normalizedOffset = Math.max(0, Math.floor(input.offset));
-  const previousOffset =
-    getTerminalResumeOffset({
-      terminalId: input.terminalId,
-      resumeOffsetStore: input.resumeOffsetStore,
-    }) ?? -1;
-  if (normalizedOffset <= previousOffset) {
-    return;
-  }
-
-  input.resumeOffsetStore.set({
-    terminalId: input.terminalId,
-    offset: normalizedOffset,
-  });
-}
-
 export function getTerminalAttachRetryDelayMs(input: { attempt: number }): number {
  const clampedAttempt = Math.max(0, input.attempt);
  const exponentialDelay = 250 * 2 ** clampedAttempt;