fix(terminal): preserve 10,000 rows with direct ANSI replay (#8282)

Restore configured terminal history on reconnect, retaining 10,000 rows plus the screen. Serialize the worker-owned xterm buffer directly to ANSI and forward negotiated bounded replay chunks while preserving ANSI-era clients and per-viewer live ordering.

Preserve captured geometry through replay, bound pressure recovery to 500 rows, and keep the omitted visible-history default at 200. Remove the full cell-grid copy and obsolete JSON rendering.

All 21 CI checks pass. Real browser, native Debug emulator/simulator and Linux Electron coverage and platform limits are documented in the PR. The Android Debug invalid native delegate dispatch also reproduces on upstream main; its cause and any change in frequency remain unproven.

Credit Manav Dhindsa (DrakenKor), #6139 and #6148, and Lennart Schoch, #6743, for prior ANSI replay and retention work informing this change.

Closes #6137.
Closes #6147.

packages/protocol/src/binary-frames/demux.test.ts

@@ -89,3 +89,18 @@ describe("host route binary framing", () => {
     ).toThrow("Invalid host route ID");
   });
 });
+
+it.each([
+  TerminalStreamOpcode.ReplayBegin,
+  TerminalStreamOpcode.ReplayData,
+  TerminalStreamOpcode.ReplayEnd,
+])("decodes replay opcode %s directly and inside a host route", (opcode) => {
+  const payload = new TextEncoder().encode("界 replay");
+  const bytes = encodeTerminalStreamFrame({ opcode, slot: 12, payload });
+  const expected = { kind: "terminal", frame: { opcode, slot: 12, payload } };
+  expect(decodeBinaryFrame(bytes)).toEqual(expected);
+  const routed = decodeBinaryFrame(encodeHostRouteFrame("host", bytes));
+  expect(routed?.kind).toBe("host_route");
+  if (routed?.kind !== "host_route") throw new Error("Missing host route");
+  expect(decodeBinaryFrame(routed.frame.payload)).toEqual(expected);
+});

packages/protocol/src/binary-frames/demux.ts

@@ -25,6 +25,9 @@ export function decodeBinaryFrame(bytes: Uint8Array): BinaryFrame | null {
     case TerminalStreamOpcode.Input:
     case TerminalStreamOpcode.Resize:
     case TerminalStreamOpcode.Snapshot:
+    case TerminalStreamOpcode.ReplayBegin:
+    case TerminalStreamOpcode.ReplayData:
+    case TerminalStreamOpcode.ReplayEnd:
     case TerminalStreamOpcode.Restore: {
       const frame = decodeTerminalStreamFrame(bytes);
       return frame ? { kind: "terminal", frame } : null;

packages/protocol/src/binary-frames/terminal.ts

@@ -1,6 +1,12 @@
 import { z } from "zod";
 import { TerminalStateSchema } from "../messages.js";
 
+export const TerminalReplayMetadataSchema = z.object({
+  rows: z.number().int().positive(),
+  cols: z.number().int().positive(),
+  retainedHistoryLines: z.number().int().nonnegative(),
+});
+
 export const TerminalStreamResizeSchema = z.object({
   rows: z.number().int().positive(),
   cols: z.number().int().positive(),
@@ -13,6 +19,9 @@ export const TerminalStreamOpcode = {
   Resize: 0x03,
   Snapshot: 0x04,
   Restore: 0x05,
+  ReplayBegin: 0x06,
+  ReplayData: 0x07,
+  ReplayEnd: 0x08,
 } as const;
 
 export type TerminalStreamOpcode = (typeof TerminalStreamOpcode)[keyof typeof TerminalStreamOpcode];
@@ -58,6 +67,9 @@ function isTerminalStreamOpcode(value: number): value is TerminalStreamOpcode {
     value === TerminalStreamOpcode.Input ||
     value === TerminalStreamOpcode.Resize ||
     value === TerminalStreamOpcode.Snapshot ||
+    value === TerminalStreamOpcode.ReplayBegin ||
+    value === TerminalStreamOpcode.ReplayData ||
+    value === TerminalStreamOpcode.ReplayEnd ||
     value === TerminalStreamOpcode.Restore
   );
 }