Simplify terminal streaming protocol

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

@@ -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({

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

@@ -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;