release(v4.6.1): bind globalThis.fetch in browser-receiver-sensitive call sites

Browsers' Window.fetch is a WebIDL bound operation; storing it as
this.fetchImpl / this.fetchFn and calling via the instance receiver
threw "Illegal invocation" on the first request. Bind once at
construction in InboxClient, LongPollBridge, and SseBridge. Reported
by Prism (multi-device E2EE terminal), blocking every browser
consumer of the v4.6 transport stack on inbox.start() / bridge.connect().

WsBridge unaffected (uses WebSocket). Node/Bun fetch tolerates a free
receiver, so the bug never surfaced server-side — added regression
tests that install a strict-receiver globalThis.fetch to catch the
issue without an actual browser harness.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/shade-transport-bridge/tests/bridge.test.ts

@@ -510,3 +510,104 @@ describe('Bridge cursor resume', () => {
     await sseB.disconnect();
   });
 });
+
+describe('Bridges — default fetch is bound to globalThis', () => {
+  // Regression: browsers' `fetch` is a WebIDL bound operation that throws
+  // "Illegal invocation" when called via `this.fetchFn(...)`. Constructors
+  // for LongPollBridge / SseBridge must `bind(globalThis)`.
+  function installStrictFetch(): { restore: () => void; getReceiver: () => unknown } {
+    const realFetch = globalThis.fetch;
+    let observedReceiver: unknown = 'unset';
+    function strictFetch(this: unknown, _input: unknown, _init?: unknown): Promise<Response> {
+      observedReceiver = this;
+      if (this !== globalThis) {
+        throw new TypeError("Failed to execute 'fetch' on 'Window': Illegal invocation");
+      }
+      return Promise.resolve(
+        new Response('{"blobs":[]}', {
+          status: 200,
+          headers: { 'content-type': 'application/json' },
+        }),
+      );
+    }
+    Object.defineProperty(globalThis, 'fetch', {
+      configurable: true,
+      writable: true,
+      value: strictFetch,
+    });
+    return {
+      restore: () =>
+        Object.defineProperty(globalThis, 'fetch', {
+          configurable: true,
+          writable: true,
+          value: realFetch,
+        }),
+      getReceiver: () => observedReceiver,
+    };
+  }
+
+  test('LongPollBridge default path passes globalThis as `this`', async () => {
+    const { restore, getReceiver } = installStrictFetch();
+    try {
+      const id = await generateIdentityKeyPair(crypto);
+      const bridge = new LongPollBridge({
+        baseUrl: 'http://example.invalid',
+        auth: { crypto, signingPrivateKey: id.signingPrivateKey, address: 'foo' },
+        pollTimeoutMs: 100,
+        requestTimeoutMs: 200,
+        errorBackoffMs: 50,
+        disableLoop: true,
+      });
+      await bridge.connect({ onMessage: () => {} });
+      expect(getReceiver()).toBe(globalThis);
+      await bridge.disconnect();
+    } finally {
+      restore();
+    }
+  });
+
+  test('SseBridge default path passes globalThis as `this`', async () => {
+    // For SSE we only need to know the very first fetch was bound; the
+    // 200-with-empty-stream response will let openOnce return cleanly,
+    // and disableAutoReconnect prevents an infinite reconnect loop.
+    const realFetch = globalThis.fetch;
+    let observedReceiver: unknown = 'unset';
+    function strictFetch(this: unknown, _input: unknown, _init?: unknown): Promise<Response> {
+      observedReceiver = this;
+      if (this !== globalThis) {
+        throw new TypeError("Failed to execute 'fetch' on 'Window': Illegal invocation");
+      }
+      // Empty SSE-shaped body: stream closes immediately.
+      return Promise.resolve(
+        new Response('', {
+          status: 200,
+          headers: { 'content-type': 'text/event-stream' },
+        }),
+      );
+    }
+    Object.defineProperty(globalThis, 'fetch', {
+      configurable: true,
+      writable: true,
+      value: strictFetch,
+    });
+    try {
+      const id = await generateIdentityKeyPair(crypto);
+      const bridge = new SseBridge({
+        baseUrl: 'http://example.invalid',
+        auth: { crypto, signingPrivateKey: id.signingPrivateKey, address: 'foo' },
+        initialBackoffMs: 50,
+        maxBackoffMs: 100,
+        disableAutoReconnect: true,
+      });
+      await bridge.connect({ onMessage: () => {} });
+      expect(observedReceiver).toBe(globalThis);
+      await bridge.disconnect();
+    } finally {
+      Object.defineProperty(globalThis, 'fetch', {
+        configurable: true,
+        writable: true,
+        value: realFetch,
+      });
+    }
+  });
+});