fix(telegram): move network fallback to resolver-scoped dispatchers (#40740)

Merged via squash.

Prepared head SHA: a4456d48b4
Co-authored-by: sircrumpet <4436535+sircrumpet@users.noreply.github.com>
Co-authored-by: obviyus <22031114+obviyus@users.noreply.github.com>
Reviewed-by: @obviyus

src/telegram/bot/delivery.resolve-media-retry.test.ts

@@ -293,6 +293,62 @@ describe("resolveMedia getFile retry", () => {
     expect(getFile).toHaveBeenCalledTimes(3);
     expect(result).toBeNull();
   });
+
+  it("uses caller-provided fetch impl for file downloads", async () => {
+    const getFile = vi.fn().mockResolvedValue({ file_path: "documents/file_42.pdf" });
+    const callerFetch = vi.fn() as unknown as typeof fetch;
+    fetchRemoteMedia.mockResolvedValueOnce({
+      buffer: Buffer.from("pdf-data"),
+      contentType: "application/pdf",
+      fileName: "file_42.pdf",
+    });
+    saveMediaBuffer.mockResolvedValueOnce({
+      path: "/tmp/file_42---uuid.pdf",
+      contentType: "application/pdf",
+    });
+
+    const result = await resolveMedia(
+      makeCtx("document", getFile),
+      MAX_MEDIA_BYTES,
+      BOT_TOKEN,
+      callerFetch,
+    );
+
+    expect(result).not.toBeNull();
+    expect(fetchRemoteMedia).toHaveBeenCalledWith(
+      expect.objectContaining({
+        fetchImpl: callerFetch,
+      }),
+    );
+  });
+
+  it("uses caller-provided fetch impl for sticker downloads", async () => {
+    const getFile = vi.fn().mockResolvedValue({ file_path: "stickers/file_0.webp" });
+    const callerFetch = vi.fn() as unknown as typeof fetch;
+    fetchRemoteMedia.mockResolvedValueOnce({
+      buffer: Buffer.from("sticker-data"),
+      contentType: "image/webp",
+      fileName: "file_0.webp",
+    });
+    saveMediaBuffer.mockResolvedValueOnce({
+      path: "/tmp/file_0.webp",
+      contentType: "image/webp",
+    });
+
+    const result = await resolveMedia(
+      makeCtx("sticker", getFile),
+      MAX_MEDIA_BYTES,
+      BOT_TOKEN,
+      callerFetch,
+    );
+
+    expect(result).not.toBeNull();
+    expect(fetchRemoteMedia).toHaveBeenCalledWith(
+      expect.objectContaining({
+        fetchImpl: callerFetch,
+      }),
+    );
+  });
 });
 
 describe("resolveMedia original filename preservation", () => {

src/telegram/bot/delivery.resolve-media.ts

@@ -92,12 +92,20 @@ async function resolveTelegramFileWithRetry(
   }
 }
 
-function resolveRequiredFetchImpl(proxyFetch?: typeof fetch): typeof fetch {
-  const fetchImpl = proxyFetch ?? globalThis.fetch;
-  if (!fetchImpl) {
+function resolveRequiredFetchImpl(fetchImpl?: typeof fetch): typeof fetch {
+  const resolved = fetchImpl ?? globalThis.fetch;
+  if (!resolved) {
     throw new Error("fetch is not available; set channels.telegram.proxy in config");
   }
-  return fetchImpl;
+  return resolved;
+}
+
+function resolveOptionalFetchImpl(fetchImpl?: typeof fetch): typeof fetch | null {
+  try {
+    return resolveRequiredFetchImpl(fetchImpl);
+  } catch {
+    return null;
+  }
 }
 
 /** Default idle timeout for Telegram media downloads (30 seconds). */
@@ -134,7 +142,7 @@ async function resolveStickerMedia(params: {
   ctx: TelegramContext;
   maxBytes: number;
   token: string;
-  proxyFetch?: typeof fetch;
+  fetchImpl?: typeof fetch;
 }): Promise<
   | {
       path: string;
@@ -145,7 +153,7 @@ async function resolveStickerMedia(params: {
   | null
   | undefined
 > {
-  const { msg, ctx, maxBytes, token, proxyFetch } = params;
+  const { msg, ctx, maxBytes, token, fetchImpl } = params;
   if (!msg.sticker) {
     return undefined;
   }
@@ -165,15 +173,15 @@ async function resolveStickerMedia(params: {
       logVerbose("telegram: getFile returned no file_path for sticker");
       return null;
     }
-    const fetchImpl = proxyFetch ?? globalThis.fetch;
-    if (!fetchImpl) {
+    const resolvedFetchImpl = resolveOptionalFetchImpl(fetchImpl);
+    if (!resolvedFetchImpl) {
       logVerbose("telegram: fetch not available for sticker download");
       return null;
     }
     const saved = await downloadAndSaveTelegramFile({
       filePath: file.file_path,
       token,
-      fetchImpl,
+      fetchImpl: resolvedFetchImpl,
       maxBytes,
     });
 
@@ -229,7 +237,7 @@ export async function resolveMedia(
   ctx: TelegramContext,
   maxBytes: number,
   token: string,
-  proxyFetch?: typeof fetch,
+  fetchImpl?: typeof fetch,
 ): Promise<{
   path: string;
   contentType?: string;
@@ -242,7 +250,7 @@ export async function resolveMedia(
     ctx,
     maxBytes,
     token,
-    proxyFetch,
+    fetchImpl,
   });
   if (stickerResolved !== undefined) {
     return stickerResolved;
@@ -263,7 +271,7 @@ export async function resolveMedia(
   const saved = await downloadAndSaveTelegramFile({
     filePath: file.file_path,
     token,
-    fetchImpl: resolveRequiredFetchImpl(proxyFetch),
+    fetchImpl: resolveRequiredFetchImpl(fetchImpl),
     maxBytes,
     telegramFileName: resolveTelegramFileName(msg),
   });