test(kernel-utils): add failing test for -0 vs +0 collapse in metadataKey

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: grypez

packages/kernel-utils/src/sheaf/sheafify.test.ts

@@ -490,6 +490,44 @@ describe('sheafify', () => {
     ]);
   });
 
+  it('does not collapse +0 and -0 metadata as equivalent', async () => {
+    type Meta = { cost: number };
+    let germCount = 0;
+
+    const sections: PresheafSection<Meta>[] = [
+      {
+        exo: makeSection(
+          'Wallet:0',
+          M.interface('Wallet:0', {
+            getBalance: M.call(M.string()).returns(M.number()),
+          }),
+          { getBalance: (_acct: string) => 0 },
+        ),
+        metadata: constant({ cost: +0 }),
+      },
+      {
+        exo: makeSection(
+          'Wallet:1',
+          M.interface('Wallet:1', {
+            getBalance: M.call(M.string()).returns(M.number()),
+          }),
+          { getBalance: (_acct: string) => 0 },
+        ),
+        metadata: constant({ cost: -0 }),
+      },
+    ];
+
+    const wallet = sheafify({ name: 'Wallet', sections }).getGlobalSection({
+      async *lift(germs) {
+        germCount = germs.length;
+        yield germs[0]!;
+      },
+    });
+
+    await E(wallet).getBalance('alice');
+    expect(germCount).toBe(2);
+  });
+
   it('does not collapse Infinity and null metadata as equivalent', async () => {
     type Meta = { cost: number | null };
     let germCount = 0;