feat(migration): add v4-to-v5 settings migration runner with backup

src/main/updater/migration-runner.js

@@ -0,0 +1,38 @@
+const fs = require('fs');
+const path = require('path');
+
+class MigrationRunner {
+  constructor({ dir, transform }) {
+    this.dir = dir;
+    this.transform = transform;
+    this.file = path.join(dir, 'settings.json');
+    this.backup = path.join(dir, 'settings.v4.bak.json');
+  }
+
+  run() {
+    if (!fs.existsSync(this.file)) {
+      this._writeDefaults();
+      return 'fresh';
+    }
+    const raw = JSON.parse(fs.readFileSync(this.file, 'utf-8'));
+    if (raw && raw['migration.version'] === 5) {
+      return 'skipped';
+    }
+    try {
+      const v5 = this.transform(raw);
+      fs.copyFileSync(this.file, this.backup);
+      fs.writeFileSync(this.file, JSON.stringify({ ...v5, 'migration.version': 5 }, null, 2));
+      return 'migrated';
+    } catch (err) {
+      console.error('[migration-runner] transform failed:', err.message);
+      return 'failed';
+    }
+  }
+
+  _writeDefaults() {
+    const v5 = this.transform({});
+    fs.writeFileSync(this.file, JSON.stringify({ ...v5, 'migration.version': 5 }, null, 2));
+  }
+}
+
+module.exports = { MigrationRunner };

src/renderer/lib/migrations/v4-to-v5.ts

@@ -0,0 +1,26 @@
+import { z } from 'zod';
+import { settingsSchema } from '@/lib/validators';
+
+export const v4SettingsSchema = z.object({
+  theme: z.enum(['light', 'dark', 'auto']).default('auto'),
+  customCss: z.string().optional().nullable(),
+  recentFiles: z.array(z.string()).default([]),
+  editorFontSize: z.number().min(10).max(28).default(14),
+  keyBindings: z.record(z.string(), z.string()).optional(),
+  snippets: z.array(z.unknown()).default([]),
+});
+
+export function migrateV4ToV5(v4: unknown): z.infer<typeof settingsSchema> {
+  const parsed = v4SettingsSchema.parse(v4);
+  const defaults = settingsSchema.parse({});
+  return {
+    ...defaults,
+    ...parsed,
+    theme: parsed.theme === 'auto' ? 'system' : parsed.theme,
+    customCssPath: parsed.customCss ?? null,
+    recentFiles: parsed.recentFiles,
+    editorFontSize: parsed.editorFontSize,
+    userBindings: parsed.keyBindings ?? defaults.userBindings ?? {},
+    snippets: parsed.snippets,
+  };
+}

src/renderer/lib/validators.ts

@@ -6,7 +6,7 @@ export const settingsSchema = z.object({
   lineNumbers: z.boolean().default(true),
   wordWrap: z.boolean().default(true),
   minimap: z.boolean().default(true),
-  theme: z.enum(['light', 'dark', 'auto']).default('auto'),
+  theme: z.enum(['light', 'dark', 'system']).default('system'),
   accentColor: z.enum(['brand', 'blue', 'green', 'purple', 'orange']).default('brand'),
   fontFamily: z.enum(['system', 'jetbrains', 'fira']).default('system'),
   pdfFormat: z.enum(['letter', 'a4', 'legal']).default('a4'),
@@ -21,6 +21,7 @@ export const settingsSchema = z.object({
   welcomeDismissed: z.boolean().default(false),
   editorFontSize: z.number().min(10).max(28).default(14),
   customCssPath: z.string().nullable().default(null),
+  userBindings: z.record(z.string(), z.string()).default({}),
 });
 export type Settings = z.infer<typeof settingsSchema>;