From 15dfa0a68c2ec3bd5459a816e66a9e065ac2452d Mon Sep 17 00:00:00 2001
From: Jannis Braun <151788261+TheZwiss@users.noreply.github.com>
Date: Sun, 3 May 2026 04:03:07 +0200
Subject: [PATCH] feat(desktop): add RecoveryStateStore with subscriber
 lifecycle

---
 packages/desktop/src/recovery.test.ts | 74 +++++++++++++++++++++++++++
 packages/desktop/src/recovery.ts      | 64 +++++++++++++++++++++++
 2 files changed, 138 insertions(+)
 create mode 100644 packages/desktop/src/recovery.test.ts
 create mode 100644 packages/desktop/src/recovery.ts

diff --git a/packages/desktop/src/recovery.test.ts b/packages/desktop/src/recovery.test.ts
new file mode 100644
index 00000000..5a94896c
--- /dev/null
+++ b/packages/desktop/src/recovery.test.ts
@@ -0,0 +1,74 @@
+import { describe, it, expect, vi } from 'vitest';
+import { RecoveryStateStore, type RecoveryState } from './recovery';
+
+describe('RecoveryStateStore', () => {
+  it('returns the initial state', () => {
+    const store = new RecoveryStateStore();
+    const s = store.get();
+    expect(s.mode).toBe('normal');
+    expect(s.reason).toBeNull();
+    expect(s.updateState).toBe('idle');
+    expect(s.updateVersion).toBeNull();
+    expect(s.lastUpdateError).toBeNull();
+    expect(s.lastCheckResult).toBeNull();
+  });
+
+  it('shallow-merges partial updates', () => {
+    const store = new RecoveryStateStore();
+    store.update({ updateState: 'checking' });
+    expect(store.get().updateState).toBe('checking');
+    expect(store.get().mode).toBe('normal');
+    store.update({ updateVersion: '1.2.3' });
+    expect(store.get().updateState).toBe('checking');
+    expect(store.get().updateVersion).toBe('1.2.3');
+  });
+
+  it('fires listeners on every update', () => {
+    const store = new RecoveryStateStore();
+    const cb = vi.fn();
+    store.subscribe(cb);
+    store.update({ updateState: 'checking' });
+    store.update({ updateState: 'idle' });
+    expect(cb).toHaveBeenCalledTimes(2);
+  });
+
+  it('subscribers receive the latest snapshot', () => {
+    const store = new RecoveryStateStore();
+    let received: RecoveryState | null = null;
+    store.subscribe((s) => { received = s; });
+    store.update({ updateState: 'downloaded', updateVersion: '2.0.0' });
+    expect(received).not.toBeNull();
+    expect(received!.updateState).toBe('downloaded');
+    expect(received!.updateVersion).toBe('2.0.0');
+  });
+
+  it('unsubscribe stops callbacks', () => {
+    const store = new RecoveryStateStore();
+    const cb = vi.fn();
+    const unsub = store.subscribe(cb);
+    store.update({ updateState: 'checking' });
+    unsub();
+    store.update({ updateState: 'idle' });
+    expect(cb).toHaveBeenCalledTimes(1);
+  });
+
+  it('multiple subscribers all receive updates', () => {
+    const store = new RecoveryStateStore();
+    const a = vi.fn();
+    const b = vi.fn();
+    store.subscribe(a);
+    store.subscribe(b);
+    store.update({ updateState: 'checking' });
+    expect(a).toHaveBeenCalledTimes(1);
+    expect(b).toHaveBeenCalledTimes(1);
+  });
+
+  it('isInRecoveryMode is false initially, true after markRecoveryEntered, false after markRecoveryExited', () => {
+    const store = new RecoveryStateStore();
+    expect(store.isInRecoveryMode()).toBe(false);
+    store.markRecoveryEntered();
+    expect(store.isInRecoveryMode()).toBe(true);
+    store.markRecoveryExited();
+    expect(store.isInRecoveryMode()).toBe(false);
+  });
+});
diff --git a/packages/desktop/src/recovery.ts b/packages/desktop/src/recovery.ts
new file mode 100644
index 00000000..002bc60c
--- /dev/null
+++ b/packages/desktop/src/recovery.ts
@@ -0,0 +1,64 @@
+export type RecoveryReasonCode =
+  | 'load-failed'
+  | 'render-gone'
+  | 'unresponsive'
+  | 'renderer-stalled';
+
+export type UpdateState =
+  | 'idle'
+  | 'checking'
+  | 'downloading'
+  | 'downloaded'
+  | 'error';
+
+export interface RecoveryState {
+  mode: 'normal' | 'recovery';
+  reason: { code: RecoveryReasonCode; detail: string } | null;
+  updateState: UpdateState;
+  updateVersion: string | null;
+  lastUpdateError: { message: string; code: string | null; at: number } | null;
+  lastCheckResult: 'up-to-date' | 'failed' | null;
+}
+
+const INITIAL_STATE: RecoveryState = {
+  mode: 'normal',
+  reason: null,
+  updateState: 'idle',
+  updateVersion: null,
+  lastUpdateError: null,
+  lastCheckResult: null,
+};
+
+export class RecoveryStateStore {
+  private state: RecoveryState = { ...INITIAL_STATE };
+  private listeners = new Set<(s: RecoveryState) => void>();
+  private inRecoveryMode = false;
+
+  get(): Readonly<RecoveryState> {
+    return this.state;
+  }
+
+  update(partial: Partial<RecoveryState>): void {
+    this.state = { ...this.state, ...partial };
+    for (const cb of this.listeners) cb(this.state);
+  }
+
+  subscribe(cb: (s: RecoveryState) => void): () => void {
+    this.listeners.add(cb);
+    return () => { this.listeners.delete(cb); };
+  }
+
+  isInRecoveryMode(): boolean {
+    return this.inRecoveryMode;
+  }
+
+  markRecoveryEntered(): void {
+    this.inRecoveryMode = true;
+  }
+
+  markRecoveryExited(): void {
+    this.inRecoveryMode = false;
+  }
+}
+
+export const recoveryStore = new RecoveryStateStore();