Harden worker probe response validation and add tests

web/apiClient.js

@@ -178,11 +178,32 @@ export function createApiClient(baseUrl) {
                     return { ok: false, status: response.status, queueRemaining: null };
                 }
 
-                const data = await response.json().catch(() => ({}));
+                let data;
+                try {
+                    data = await response.json();
+                } catch {
+                    return { ok: false, status: response.status, queueRemaining: null };
+                }
+
+                if (!data || typeof data !== "object" || Array.isArray(data)) {
+                    return { ok: false, status: response.status, queueRemaining: null };
+                }
+
+                const execInfo = data.exec_info;
+                if (!execInfo || typeof execInfo !== "object" || Array.isArray(execInfo)) {
+                    return { ok: false, status: response.status, queueRemaining: null };
+                }
+
+                const rawQueueRemaining = execInfo.queue_remaining;
+                const queueRemaining = Number(rawQueueRemaining);
+                if (!Number.isFinite(queueRemaining)) {
+                    return { ok: false, status: response.status, queueRemaining: null };
+                }
+
                 return {
                     ok: true,
                     status: response.status,
-                    queueRemaining: data.exec_info?.queue_remaining || 0,
+                    queueRemaining: Math.max(0, queueRemaining),
                 };
             } finally {
                 clearTimeout(timeoutId);

web/tests/apiClient.test.js

@@ -0,0 +1,95 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+import { createApiClient } from "../apiClient.js";
+
+describe("apiClient probeWorker", () => {
+    let originalFetch;
+
+    beforeEach(() => {
+        originalFetch = globalThis.fetch;
+        globalThis.fetch = vi.fn();
+    });
+
+    afterEach(() => {
+        globalThis.fetch = originalFetch;
+        vi.restoreAllMocks();
+    });
+
+    it("returns ok=true when /prompt returns valid exec_info payload", async () => {
+        globalThis.fetch.mockResolvedValue({
+            ok: true,
+            status: 200,
+            json: vi.fn().mockResolvedValue({ exec_info: { queue_remaining: 2 } }),
+        });
+
+        const client = createApiClient("http://127.0.0.1:8188");
+        const result = await client.probeWorker("http://worker.local:8190", 1000);
+
+        expect(result).toEqual({ ok: true, status: 200, queueRemaining: 2 });
+    });
+
+    it("returns ok=false on non-200 responses", async () => {
+        globalThis.fetch.mockResolvedValue({
+            ok: false,
+            status: 503,
+            json: vi.fn(),
+        });
+
+        const client = createApiClient("http://127.0.0.1:8188");
+        const result = await client.probeWorker("http://worker.local:8190", 1000);
+
+        expect(result).toEqual({ ok: false, status: 503, queueRemaining: null });
+    });
+
+    it("returns ok=false when response JSON is invalid", async () => {
+        globalThis.fetch.mockResolvedValue({
+            ok: true,
+            status: 200,
+            json: vi.fn().mockRejectedValue(new Error("invalid json")),
+        });
+
+        const client = createApiClient("http://127.0.0.1:8188");
+        const result = await client.probeWorker("http://worker.local:8190", 1000);
+
+        expect(result).toEqual({ ok: false, status: 200, queueRemaining: null });
+    });
+
+    it("returns ok=false when exec_info is missing", async () => {
+        globalThis.fetch.mockResolvedValue({
+            ok: true,
+            status: 200,
+            json: vi.fn().mockResolvedValue({}),
+        });
+
+        const client = createApiClient("http://127.0.0.1:8188");
+        const result = await client.probeWorker("http://worker.local:8190", 1000);
+
+        expect(result).toEqual({ ok: false, status: 200, queueRemaining: null });
+    });
+
+    it("returns ok=false when queue_remaining is not numeric", async () => {
+        globalThis.fetch.mockResolvedValue({
+            ok: true,
+            status: 200,
+            json: vi.fn().mockResolvedValue({ exec_info: { queue_remaining: "n/a" } }),
+        });
+
+        const client = createApiClient("http://127.0.0.1:8188");
+        const result = await client.probeWorker("http://worker.local:8190", 1000);
+
+        expect(result).toEqual({ ok: false, status: 200, queueRemaining: null });
+    });
+
+    it("clamps negative queue_remaining to zero", async () => {
+        globalThis.fetch.mockResolvedValue({
+            ok: true,
+            status: 200,
+            json: vi.fn().mockResolvedValue({ exec_info: { queue_remaining: -5 } }),
+        });
+
+        const client = createApiClient("http://127.0.0.1:8188");
+        const result = await client.probeWorker("http://worker.local:8190", 1000);
+
+        expect(result).toEqual({ ok: true, status: 200, queueRemaining: 0 });
+    });
+});