diff --git a/src/plugins/interactive.test.ts b/src/plugins/interactive.test.ts
index f794cde4037..7605a6b3655 100644
--- a/src/plugins/interactive.test.ts
+++ b/src/plugins/interactive.test.ts
@@ -89,6 +89,30 @@ describe("plugin interactive handlers", () => {
     });
   });
 
+  it("rejects unsupported interactive channels and malformed handlers", () => {
+    expect(
+      registerPluginInteractiveHandler("plugin-a", {
+        channel: "slack",
+        namespace: "codex",
+        handler: async () => ({ handled: true }),
+      } as unknown as Parameters<typeof registerPluginInteractiveHandler>[1]),
+    ).toEqual({
+      ok: false,
+      error: 'Interactive handler channel must be either "telegram" or "discord"',
+    });
+
+    expect(
+      registerPluginInteractiveHandler("plugin-a", {
+        channel: "telegram",
+        namespace: "codex",
+        handler: "not-a-function",
+      } as unknown as Parameters<typeof registerPluginInteractiveHandler>[1]),
+    ).toEqual({
+      ok: false,
+      error: "Interactive handler must be a function",
+    });
+  });
+
   it("routes Discord interactions by namespace and dedupes interaction ids", async () => {
     const handler = vi.fn(async () => ({ handled: true }));
     expect(
@@ -198,4 +222,128 @@ describe("plugin interactive handlers", () => {
     });
     expect(handler).toHaveBeenCalledTimes(2);
   });
+
+  it("does not share dedupe keys across channels", async () => {
+    const telegramHandler = vi.fn(async () => ({ handled: true }));
+    const discordHandler = vi.fn(async () => ({ handled: true }));
+    expect(
+      registerPluginInteractiveHandler("codex-plugin", {
+        channel: "telegram",
+        namespace: "codex",
+        handler: telegramHandler,
+      }),
+    ).toEqual({ ok: true });
+    expect(
+      registerPluginInteractiveHandler("codex-plugin", {
+        channel: "discord",
+        namespace: "codex",
+        handler: discordHandler,
+      }),
+    ).toEqual({ ok: true });
+
+    const telegramResult = await dispatchPluginInteractiveHandler({
+      channel: "telegram",
+      data: "codex:resume",
+      callbackId: "same-id",
+      ctx: {
+        accountId: "default",
+        callbackId: "same-id",
+        conversationId: "chat-1",
+        senderId: "user-1",
+        senderUsername: "ada",
+        isGroup: false,
+        isForum: false,
+        auth: { isAuthorizedSender: true },
+        callbackMessage: {
+          messageId: 1,
+          chatId: "chat-1",
+        },
+      },
+      respond: {
+        reply: vi.fn(async () => {}),
+        editMessage: vi.fn(async () => {}),
+        editButtons: vi.fn(async () => {}),
+        clearButtons: vi.fn(async () => {}),
+        deleteMessage: vi.fn(async () => {}),
+      },
+    });
+    const discordResult = await dispatchPluginInteractiveHandler({
+      channel: "discord",
+      data: "codex:resume",
+      interactionId: "same-id",
+      ctx: {
+        accountId: "default",
+        interactionId: "same-id",
+        conversationId: "channel-1",
+        senderId: "user-1",
+        senderUsername: "ada",
+        auth: { isAuthorizedSender: true },
+        interaction: {
+          kind: "button",
+        },
+      },
+      respond: {
+        acknowledge: vi.fn(async () => {}),
+        reply: vi.fn(async () => {}),
+        followUp: vi.fn(async () => {}),
+        editMessage: vi.fn(async () => {}),
+        clearComponents: vi.fn(async () => {}),
+      },
+    });
+
+    expect(telegramResult).toEqual({ matched: true, handled: true, duplicate: false });
+    expect(discordResult).toEqual({ matched: true, handled: true, duplicate: false });
+    expect(telegramHandler).toHaveBeenCalledTimes(1);
+    expect(discordHandler).toHaveBeenCalledTimes(1);
+  });
+
+  it("does not consume dedupe keys when a handler declines", async () => {
+    const handler = vi
+      .fn(async () => ({ handled: false }))
+      .mockResolvedValueOnce({ handled: false })
+      .mockResolvedValueOnce({ handled: true });
+    expect(
+      registerPluginInteractiveHandler("codex-plugin", {
+        channel: "discord",
+        namespace: "codex",
+        handler,
+      }),
+    ).toEqual({ ok: true });
+
+    const baseParams = {
+      channel: "discord" as const,
+      data: "codex:approve:thread-1",
+      interactionId: "ix-decline",
+      ctx: {
+        accountId: "default",
+        interactionId: "ix-decline",
+        conversationId: "channel-1",
+        senderId: "user-1",
+        senderUsername: "ada",
+        auth: { isAuthorizedSender: true },
+        interaction: {
+          kind: "button" as const,
+        },
+      },
+      respond: {
+        acknowledge: vi.fn(async () => {}),
+        reply: vi.fn(async () => {}),
+        followUp: vi.fn(async () => {}),
+        editMessage: vi.fn(async () => {}),
+        clearComponents: vi.fn(async () => {}),
+      },
+    };
+
+    await expect(dispatchPluginInteractiveHandler(baseParams)).resolves.toEqual({
+      matched: true,
+      handled: false,
+      duplicate: false,
+    });
+    await expect(dispatchPluginInteractiveHandler(baseParams)).resolves.toEqual({
+      matched: true,
+      handled: true,
+      duplicate: false,
+    });
+    expect(handler).toHaveBeenCalledTimes(2);
+  });
 });