Reject top-level JSON arrays in the project trust store shape check

The arktype object schema accepts arrays (they are typeof "object"),
so a trust-store file containing a bare JSON array silently degraded
to an empty-but-valid store instead of being flagged invalid. Explicit
Array.isArray check restores the original rejection before validation.

Author: TheGreatAxios

src/trust/project-trust.ts

@@ -104,6 +104,14 @@ export async function readProjectTrustStore(
     logger.warn`project trust store is not valid JSON at ${path}: ${String(err)}`;
     return { state: "invalid", store: emptyStore() };
   }
+  // arktype's plain object schema accepts arrays (Array.isArray(x) && typeof x
+  // === "object"), so a top-level JSON array must be rejected explicitly before
+  // validation — otherwise it degrades to an empty-but-"valid" store instead of
+  // being flagged corrupt.
+  if (Array.isArray(parsed)) {
+    logger.warn`project trust store has an invalid shape at ${path}: expected object, got array`;
+    return { state: "invalid", store: emptyStore() };
+  }
   const validated = ProjectTrustRecordSchema(parsed);
   if (validated instanceof type.errors) {
     logger.warn`project trust store has an invalid shape at ${path}: ${validated.summary}`;

tests/unit/project-trust.test.ts

@@ -164,6 +164,42 @@ describe("project-trust", () => {
     }
   });
 
+  test("readProjectTrustStore: top-level JSON array is invalid", async () => {
+    const { cwd, home, cleanup } = await scratch();
+    try {
+      const path = projectTrustPath(cwd, home);
+      await mkdir(join(home, ".corbits", "trust"), { recursive: true });
+      await writeFile(path, JSON.stringify([1, 2, 3]), "utf8");
+      const result = await readProjectTrustStore(cwd, home);
+      expect(result.state).toBe("invalid");
+      expect(result.store).toEqual({ trustedPluginPaths: [], trustedMcpFingerprints: [] });
+    } finally {
+      await cleanup();
+    }
+  });
+
+  test("readProjectTrustStore: non-string repo field is invalid", async () => {
+    const { cwd, home, cleanup } = await scratch();
+    try {
+      const path = projectTrustPath(cwd, home);
+      await mkdir(join(home, ".corbits", "trust"), { recursive: true });
+      await writeFile(
+        path,
+        JSON.stringify({
+          repo: 7,
+          trustedPluginPaths: [],
+          trustedMcpFingerprints: [],
+        }),
+        "utf8",
+      );
+      const result = await readProjectTrustStore(cwd, home);
+      expect(result.state).toBe("invalid");
+      expect(result.store).toEqual({ trustedPluginPaths: [], trustedMcpFingerprints: [] });
+    } finally {
+      await cleanup();
+    }
+  });
+
   test("readProjectTrustStore: partial file with only trustedPluginPaths stays valid", async () => {
     const { cwd, home, cleanup } = await scratch();
     try {