Fix terminal renderer remount loading

packages/app/src/utils/terminal-renderer-readiness.test.ts

@@ -0,0 +1,96 @@
+import { describe, expect, it } from "vitest";
+
+import {
+  applyTerminalRendererReadyChange,
+  shouldReplayTerminalSnapshotForRenderer,
+  shouldShowTerminalLoadingOverlay,
+} from "./terminal-renderer-readiness";
+
+describe("terminal-renderer-readiness", () => {
+  it("preserves the attach loader even after the renderer is ready", () => {
+    expect(
+      shouldShowTerminalLoadingOverlay({
+        isWorkspaceFocused: true,
+        hasStreamError: false,
+        isAttaching: true,
+        rendererReadyStreamKey: "scope:terminal-1",
+        terminalStreamKey: "scope:terminal-1",
+      }),
+    ).toBe(true);
+  });
+
+  it("keeps the loader visible until the current renderer is ready", () => {
+    expect(
+      shouldShowTerminalLoadingOverlay({
+        isWorkspaceFocused: true,
+        hasStreamError: false,
+        isAttaching: false,
+        rendererReadyStreamKey: null,
+        terminalStreamKey: "scope:terminal-1",
+      }),
+    ).toBe(true);
+  });
+
+  it("hides the loader only after attach completes and the current renderer is ready", () => {
+    expect(
+      shouldShowTerminalLoadingOverlay({
+        isWorkspaceFocused: true,
+        hasStreamError: false,
+        isAttaching: false,
+        rendererReadyStreamKey: "scope:terminal-1",
+        terminalStreamKey: "scope:terminal-1",
+      }),
+    ).toBe(false);
+  });
+
+  it("does not cover stream errors", () => {
+    expect(
+      shouldShowTerminalLoadingOverlay({
+        isWorkspaceFocused: true,
+        hasStreamError: true,
+        isAttaching: true,
+        rendererReadyStreamKey: null,
+        terminalStreamKey: "scope:terminal-1",
+      }),
+    ).toBe(false);
+  });
+
+  it("ignores stale unready events from an old renderer", () => {
+    const current = applyTerminalRendererReadyChange("scope:terminal-2", {
+      streamKey: "scope:terminal-1",
+      isReady: false,
+    });
+
+    expect(current).toBe("scope:terminal-2");
+  });
+
+  it("clears readiness when the current renderer unmounts", () => {
+    const current = applyTerminalRendererReadyChange("scope:terminal-1", {
+      streamKey: "scope:terminal-1",
+      isReady: false,
+    });
+
+    expect(current).toBeNull();
+  });
+
+  it("replays snapshots only for ready events from the current renderer", () => {
+    expect(
+      shouldReplayTerminalSnapshotForRenderer({
+        change: { streamKey: "scope:terminal-1", isReady: true },
+        terminalStreamKey: "scope:terminal-1",
+      }),
+    ).toBe(true);
+    expect(
+      shouldReplayTerminalSnapshotForRenderer({
+        change: { streamKey: "scope:terminal-1", isReady: false },
+        terminalStreamKey: "scope:terminal-1",
+      }),
+    ).toBe(false);
+    expect(
+      shouldReplayTerminalSnapshotForRenderer({
+        change: { streamKey: "scope:terminal-1", isReady: true },
+        terminalStreamKey: "scope:terminal-2",
+      }),
+    ).toBe(false);
+  });
+});

packages/app/src/utils/terminal-renderer-readiness.ts

@@ -0,0 +1,36 @@
+export interface TerminalRendererReadyChange {
+  streamKey: string;
+  isReady: boolean;
+}
+
+export function applyTerminalRendererReadyChange(
+  currentReadyStreamKey: string | null,
+  change: TerminalRendererReadyChange,
+): string | null {
+  if (change.isReady) {
+    return change.streamKey;
+  }
+
+  return currentReadyStreamKey === change.streamKey ? null : currentReadyStreamKey;
+}
+
+export function shouldReplayTerminalSnapshotForRenderer(input: {
+  change: TerminalRendererReadyChange;
+  terminalStreamKey: string;
+}): boolean {
+  return input.change.isReady && input.change.streamKey === input.terminalStreamKey;
+}
+
+export function shouldShowTerminalLoadingOverlay(input: {
+  isWorkspaceFocused: boolean;
+  hasStreamError: boolean;
+  isAttaching: boolean;
+  rendererReadyStreamKey: string | null;
+  terminalStreamKey: string;
+}): boolean {
+  return (
+    input.isWorkspaceFocused &&
+    !input.hasStreamError &&
+    (input.isAttaching || input.rendererReadyStreamKey !== input.terminalStreamKey)
+  );
+}