diff --git a/src/plugins/contracts/registry.contract.test.ts b/src/plugins/contracts/registry.contract.test.ts
new file mode 100644
index 00000000000..a87261fe58c
--- /dev/null
+++ b/src/plugins/contracts/registry.contract.test.ts
@@ -0,0 +1,43 @@
+import { describe, expect, it } from "vitest";
+import { providerContractRegistry, webSearchProviderContractRegistry } from "./registry.js";
+
+function findProviderIdsForPlugin(pluginId: string) {
+  return providerContractRegistry
+    .filter((entry) => entry.pluginId === pluginId)
+    .map((entry) => entry.provider.id)
+    .toSorted((left, right) => left.localeCompare(right));
+}
+
+function findWebSearchIdsForPlugin(pluginId: string) {
+  return webSearchProviderContractRegistry
+    .filter((entry) => entry.pluginId === pluginId)
+    .map((entry) => entry.provider.id)
+    .toSorted((left, right) => left.localeCompare(right));
+}
+
+describe("plugin contract registry", () => {
+  it("does not duplicate bundled provider ids", () => {
+    const ids = providerContractRegistry.map((entry) => entry.provider.id);
+    expect(ids).toEqual([...new Set(ids)]);
+  });
+
+  it("does not duplicate bundled web search provider ids", () => {
+    const ids = webSearchProviderContractRegistry.map((entry) => entry.provider.id);
+    expect(ids).toEqual([...new Set(ids)]);
+  });
+
+  it("keeps multi-provider plugin ownership explicit", () => {
+    expect(findProviderIdsForPlugin("google")).toEqual(["google", "google-gemini-cli"]);
+    expect(findProviderIdsForPlugin("minimax")).toEqual(["minimax", "minimax-portal"]);
+    expect(findProviderIdsForPlugin("openai")).toEqual(["openai", "openai-codex"]);
+  });
+
+  it("keeps bundled web search ownership explicit", () => {
+    expect(findWebSearchIdsForPlugin("brave")).toEqual(["brave"]);
+    expect(findWebSearchIdsForPlugin("firecrawl")).toEqual(["firecrawl"]);
+    expect(findWebSearchIdsForPlugin("google")).toEqual(["gemini"]);
+    expect(findWebSearchIdsForPlugin("moonshot")).toEqual(["kimi"]);
+    expect(findWebSearchIdsForPlugin("perplexity")).toEqual(["perplexity"]);
+    expect(findWebSearchIdsForPlugin("xai")).toEqual(["grok"]);
+  });
+});