fix(cli): read Wrangler configs that start with a UTF-8 BOM

Bug: a root wrangler.jsonc/wrangler.json saved with a UTF-8 BOM (common
for files written by Windows editors) is valid for Wrangler, but Void
treats it as unreadable. `vite dev` / `vite build` stop with "db: cannot
read malformed Wrangler configuration". `void deploy --platform
cloudflare` on an app with a durable-objects/ file treats the file as
missing and overwrites it with only `durable_objects` and `migrations`,
so `name`, `main`, `routes` and every other key are lost. For typed
projects the truncated config is then saved as the lock's resolved
state. The managed deploy live-binding sync reaches the same reader.
Plain `void deploy` (no --platform, no saved destination), which the
deployment guide names as the way to link an existing Worker, stops
with "Set the existing Worker's name in a valid wrangler.jsonc before
linking to Cloudflare." even though the name is set.

Repro: write wrangler.jsonc as U+FEFF + `{ // app, "name": "existing",
"main": ..., "routes": [...] }`, then call syncWranglerDurableObjects()
with one Durable Object module (or readRootWranglerConfig()). The file
ends up as `{ durable_objects, migrations }` (or the reader throws
"Failed to parse JSONC"). With the same BOM file and no saved
destination, maybeLinkCloudflareDeploy() throws instead of offering to
link the Worker.

Cause: two JSONC readers pass the text straight to jsonc-parser: the
private parseJsonc() in packages/void/src/cli/wrangler.ts and the
onboarding check in maybeLinkCloudflareDeploy()
(packages/void/src/cli/cloudflare-link.ts). Node's utf-8 read keeps the
BOM. jsonc-parser still returns the object, but also reports the BOM as
a syntax error at offset 0, and both readers treat any error as a bad
file. readOrCreateProjectWranglerConfig() swallows that error and
returns an empty config with created: true, so its callers write their
keys over the user's file. Void's other JSONC readers
(generated-wrangler-config, migrate) and the comment-preserving writers
in wrangler.ts already strip the BOM.

Fix: strip one leading BOM before parsing in both readers. In
wrangler.ts, parseJsonc() uses the file's existing UTF8_BOM constant,
which fixes every reader in that file at once
(readOrCreateProjectWranglerConfig, readRootWranglerConfig, the Durable
Object, compat and WebSocket readers). In cloudflare-link.ts the
onboarding read uses the same `.replace(/^\uFEFF/, '')` as
generated-wrangler-config; its checks and error messages are unchanged,
and it still never writes the file. No other behaviour changes.

Test:
- packages/void/test/unit/wrangler.test.ts, "keeps existing keys of a
  BOM-prefixed config when adding Durable Objects". Without the fix
  readRootWranglerConfig() throws "Failed to parse JSONC", and the sync
  replaces the file with only durable_objects and migrations.
- packages/void/test/unit/cloudflare-link.test.ts, "offers to link a
  Worker whose config starts with a UTF-8 BOM". Without the fix
  maybeLinkCloudflareDeploy() throws "Set the existing Worker's name in
  a valid wrangler.jsonc"; with it, it returns 'existing' and the file
  bytes, BOM included, are unchanged.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0123r5HnanmW2VUrZ7VWDufH

Author: Brooooooklyn

packages/void/src/cli/cloudflare-link.ts

@@ -225,7 +225,7 @@ export async function maybeLinkCloudflareDeploy(
   }
   const errors: Array<ParseError> = [];
   const configPath = files.length ? join(root, name) : materializeCloudflareConfig(root);
-  const config = parse(readFileSync(configPath, 'utf8'), errors, {
+  const config = parse(readFileSync(configPath, 'utf8').replace(/^\uFEFF/, ''), errors, {
     allowTrailingComma: true,
   });
   if (!files.length && (!config || typeof config.name !== 'string' || !config.name.trim())) {

packages/void/src/cli/wrangler.ts

@@ -1771,7 +1771,8 @@ function detectFormattingOptions(text: string): FormattingOptions {
 
 function parseJsonc(text: string): Record<string, unknown> {
   const errors: Array<ParseError> = [];
-  const result = parse(text, errors, { allowTrailingComma: true });
+  const source = text.startsWith(UTF8_BOM) ? text.slice(UTF8_BOM.length) : text;
+  const result = parse(source, errors, { allowTrailingComma: true });
   if (errors.length > 0) {
     throw new SyntaxError('Failed to parse JSONC');
   }

packages/void/test/unit/cloudflare-link.test.ts

@@ -35,6 +35,18 @@ describe('Cloudflare deployment onboarding', () => {
     expect(readDeploymentPlatform(root)).toBeNull();
     expect(readFileSync(join(root, 'wrangler.jsonc'), 'utf8')).toBe(config);
   });
+  it('offers to link a Worker whose config starts with a UTF-8 BOM', async () => {
+    const bomConfig = `\uFEFF${config}`;
+    writeFileSync(join(root, 'wrangler.jsonc'), bomConfig);
+    expect(
+      await maybeLinkCloudflareDeploy(
+        root,
+        {},
+        { interactive: true, confirm: vi.fn().mockResolvedValue(true) },
+      ),
+    ).toBe('existing');
+    expect(readFileSync(join(root, 'wrangler.jsonc'), 'utf8')).toBe(bomConfig);
+  });
   it('offers to link a Worker configured through a custom Astro JSONC path', async () => {
     rmSync(join(root, 'wrangler.jsonc'));
     writeFileSync(join(root, 'wrangler.build.jsonc'), config);

packages/void/test/unit/wrangler.test.ts

@@ -13,6 +13,7 @@ import {
   LATEST_KNOWN_COMPAT_DATE,
   readExistingLiveBindingConfig,
   readProvisionedBindingEntry,
+  readRootWranglerConfig,
   readWranglerCompat,
   readWranglerManagedQueueCleanupCandidates,
   readWranglerWebSocketTombstones,
@@ -549,6 +550,39 @@ describe('syncWranglerBindings', () => {
     ]);
   });
 
+  it('keeps existing keys of a BOM-prefixed config when adding Durable Objects', () => {
+    setup(
+      'wrangler.jsonc',
+      '' +
+        `{
+  // app
+  "name": "existing",
+  "main": "src/index.ts",
+  "routes": [{ "pattern": "example.com", "custom_domain": true }]
+}`,
+    );
+    expect(readRootWranglerConfig(tmpDir)?.config.name).toBe('existing');
+
+    const counter = {
+      filePath: join(tmpDir, 'durable-objects', 'counter.ts'),
+      bindingName: 'COUNTER',
+      className: 'CounterDurableObject',
+      migrationTag: 'void-durable-counter-v1',
+    };
+    expect(syncWranglerDurableObjects(tmpDir, [counter])).toBe(true);
+    const parsed = JSON.parse(readFileSync(join(tmpDir, 'wrangler.jsonc'), 'utf-8'));
+
+    expect(parsed).toMatchObject({
+      name: 'existing',
+      main: 'src/index.ts',
+      routes: [{ pattern: 'example.com', custom_domain: true }],
+      durable_objects: { bindings: [{ name: 'COUNTER', class_name: 'CounterDurableObject' }] },
+      migrations: [
+        { tag: 'void-durable-counter-v1', new_sqlite_classes: ['CounterDurableObject'] },
+      ],
+    });
+  });
+
   it('adds live durable object and SQLite migration metadata', () => {
     setup('wrangler.jsonc', '{ "name": "test" }');
     const result = syncWranglerBindings(tmpDir, { ...noBindings, needsLive: true });