Fix terminal snapshots reflowing after resize

Terminal snapshots now carry soft-wrap row metadata only to clients that advertise support, so restored output can resize like live output without breaking older clients.
2026-05-31 19:40:15 +07:00
parent 794cbcef63
commit 4cc72a84e8
18 changed files with 538 additions and 146 deletions
@@ -0,0 +1,49 @@
+import { describe, it, expect } from "vitest";
+import { renderTerminalSnapshotToAnsi } from "./terminal-snapshot";
+import type { TerminalState } from "./messages";
+
+function cells(text: string): TerminalState["grid"][number] {
+  return [...text].map((char) => ({ char }));
+}
+
+describe("renderTerminalSnapshotToAnsi", () => {
+  it("renders soft-wrapped rows as one contiguous logical line when wrap flags are present", () => {
+    // The server soft-wrapped one logical line "ABCDEFGHIJKLMNOP" at 10 cols into
+    // two grid rows. gridWrapped[0] = true marks row 0 as continuing into row 1.
+    const state: TerminalState = {
+      rows: 2,
+      cols: 10,
+      scrollback: [],
+      scrollbackWrapped: [],
+      grid: [cells("ABCDEFGHIJ"), cells("KLMNOP")],
+      gridWrapped: [true, false],
+      cursor: { row: 1, col: 6 },
+    };
+
+    const ansi = renderTerminalSnapshotToAnsi(state);
+
+    // The rows must arrive unbroken so xterm re-wraps them itself (and can later
+    // reflow them) — no hard newline injected between "...IJ" and "KL...".
+    expect(ansi).toContain("ABCDEFGHIJKLMNOP");
+    // Auto-wrap must stay enabled; disabling it (ESC[?7l) is what makes xterm mark
+    // the rows non-wrapped and refuse to reflow them on resize.
+    expect(ansi).not.toContain("[?7l");
+  });
+
+  it("falls back to verbatim per-row replay when wrap flags are absent (old daemon)", () => {
+    // No gridWrapped/scrollbackWrapped: the client cannot tell soft-wraps from hard
+    // newlines, so it must keep today's exact behaviour rather than guess.
+    const state: TerminalState = {
+      rows: 2,
+      cols: 10,
+      scrollback: [],
+      grid: [cells("ABCDEFGHIJ"), cells("KLMNOP")],
+      cursor: { row: 1, col: 6 },
+    };
+
+    const ansi = renderTerminalSnapshotToAnsi(state);
+
+    expect(ansi).toContain("[?7l");
+    expect(ansi).toContain("ABCDEFGHIJ\r\nKLMNOP");
+  });
+});