test(app): reproduce terminal scrollback lost when a terminal re-attaches

Repro for #6137. Fails on main: 3007 lines before a reload, 246 after.
2026-10-14 13:22:37 +00:00 · 2026-10-05 15:36:35 +02:00
parent dfb8a1a2bc
commit 85d98e9ad7
1 changed files with 62 additions and 0 deletions
@@ -0,0 +1,62 @@
+import type { Page } from "@playwright/test";
+import { test, expect } from "../support/fixtures";
+import { TerminalE2EHarness } from "../support/helpers/terminal-dsl";
+import { waitForTerminalContent } from "../support/helpers/terminal-perf";
+
+interface ScrollbackProbe {
+  bufferLines: number;
+  oldestSeqLine: string;
+}
+
+interface InspectableTerminal {
+  buffer: {
+    active: {
+      length: number;
+      getLine(index: number): { translateToString(trimRight: boolean): string } | undefined;
+    };
+  };
+}
+
+async function readScrollback(page: Page): Promise<ScrollbackProbe> {
+  return page.evaluate(() => {
+    const terminal = (window as Window & { __paseoTerminal?: InspectableTerminal }).__paseoTerminal;
+    if (!terminal) {
+      return { bufferLines: 0, oldestSeqLine: "" };
+    }
+    const buffer = terminal.buffer.active;
+    for (let index = 0; index < buffer.length; index++) {
+      const text = buffer.getLine(index)?.translateToString(true).trim() ?? "";
+      if (/^\d+$/.test(text)) {
+        return { bufferLines: buffer.length, oldestSeqLine: text };
+      }
+    }
+    return { bufferLines: buffer.length, oldestSeqLine: "" };
+  });
+}
+
+async function readScrollbackAfterSeq(page: Page): Promise<ScrollbackProbe> {
+  await waitForTerminalContent(page, (text) => text.includes("\n3000"), 30_000);
+  return readScrollback(page);
+}
+
+// Repro for https://github.com/getpaseo/paseo/issues/6137: a reload re-attaches the
+// terminal from a daemon restore, which keeps far fewer lines than the live buffer held.
+test("a re-attached terminal keeps its scrollback after a reload", async ({ page }) => {
+  const harness = await TerminalE2EHarness.create({ tempPrefix: "terminal-reattach-" });
+  try {
+    const terminal = await harness.createTerminal({ name: "seq" });
+    await harness.openTerminal(page, { terminalId: terminal.id });
+    await harness.setupPrompt(page);
+    await harness.terminalSurface(page).pressSequentially("seq 1 3000\n", { delay: 0 });
+    const beforeReload = await readScrollbackAfterSeq(page);
+    expect(beforeReload.oldestSeqLine).toBe("1");
+
+    await page.reload();
+    await harness.openTerminal(page, { terminalId: terminal.id });
+    const afterReload = await readScrollbackAfterSeq(page);
+
+    expect(afterReload, JSON.stringify({ beforeReload, afterReload })).toEqual(beforeReload);
+  } finally {
+    await harness.cleanup();
+  }
+});