fix: validate edge tts output file is non-empty before reporting success (#43385) thanks @Huntterxx

Merged after review.\n\nSmall, scoped fix: treat 0-byte Edge TTS output as failure so provider fallback can continue.

src/tts/edge-tts-validation.test.ts

@@ -0,0 +1,69 @@
+import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import path from "node:path";
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+let mockTtsPromise = vi.fn<(text: string, filePath: string) => Promise<void>>();
+
+vi.mock("node-edge-tts", () => ({
+  EdgeTTS: class {
+    ttsPromise(text: string, filePath: string) {
+      return mockTtsPromise(text, filePath);
+    }
+  },
+}));
+
+const { edgeTTS } = await import("./tts-core.js");
+
+const baseEdgeConfig = {
+  enabled: true,
+  voice: "en-US-MichelleNeural",
+  lang: "en-US",
+  outputFormat: "audio-24khz-48kbitrate-mono-mp3",
+  outputFormatConfigured: false,
+  saveSubtitles: false,
+};
+
+describe("edgeTTS – empty audio validation", () => {
+  let tempDir: string;
+
+  afterEach(() => {
+    rmSync(tempDir, { recursive: true, force: true });
+  });
+
+  it("throws when the output file is 0 bytes", async () => {
+    tempDir = mkdtempSync(path.join(tmpdir(), "tts-test-"));
+    const outputPath = path.join(tempDir, "voice.mp3");
+
+    mockTtsPromise = vi.fn(async (_text: string, filePath: string) => {
+      writeFileSync(filePath, "");
+    });
+
+    await expect(
+      edgeTTS({
+        text: "Hello",
+        outputPath,
+        config: baseEdgeConfig,
+        timeoutMs: 10000,
+      }),
+    ).rejects.toThrow("Edge TTS produced empty audio file");
+  });
+
+  it("succeeds when the output file has content", async () => {
+    tempDir = mkdtempSync(path.join(tmpdir(), "tts-test-"));
+    const outputPath = path.join(tempDir, "voice.mp3");
+
+    mockTtsPromise = vi.fn(async (_text: string, filePath: string) => {
+      writeFileSync(filePath, Buffer.from([0xff, 0xfb, 0x90, 0x00]));
+    });
+
+    await expect(
+      edgeTTS({
+        text: "Hello",
+        outputPath,
+        config: baseEdgeConfig,
+        timeoutMs: 10000,
+      }),
+    ).resolves.toBeUndefined();
+  });
+});

src/tts/tts-core.ts

@@ -1,4 +1,4 @@
-import { rmSync } from "node:fs";
+import { rmSync, statSync } from "node:fs";
 import { completeSimple, type TextContent } from "@mariozechner/pi-ai";
 import { EdgeTTS } from "node-edge-tts";
 import { ensureCustomApiRegistered } from "../agents/custom-api-registry.js";
@@ -715,4 +715,10 @@ export async function edgeTTS(params: {
     timeout: config.timeoutMs ?? timeoutMs,
   });
   await tts.ttsPromise(text, outputPath);
+
+  const { size } = statSync(outputPath);
+
+  if (size === 0) {
+    throw new Error("Edge TTS produced empty audio file");
+  }
 }