refactor: unify inline directives and media fetch

src/slack/monitor.ts

@@ -45,7 +45,7 @@ import {
 import { danger, logVerbose, shouldLogVerbose } from "../globals.js";
 import { enqueueSystemEvent } from "../infra/system-events.js";
 import { getChildLogger } from "../logging.js";
-import { detectMime } from "../media/mime.js";
+import { fetchRemoteMedia } from "../media/fetch.js";
 import { saveMediaBuffer } from "../media/store.js";
 import { buildPairingReply } from "../pairing/pairing-messages.js";
 import {
@@ -355,27 +355,28 @@ async function resolveSlackMedia(params: {
     const url = file.url_private_download ?? file.url_private;
     if (!url) continue;
     try {
-      const res = await fetch(url, {
-        headers: { Authorization: `Bearer ${params.token}` },
-      });
-      if (!res.ok) continue;
-      const buffer = Buffer.from(await res.arrayBuffer());
-      if (buffer.byteLength > params.maxBytes) continue;
-      const contentType = await detectMime({
-        buffer,
-        headerMime: res.headers.get("content-type"),
-        filePath: file.name,
+      const fetchImpl: typeof fetch = (input, init) => {
+        const headers = new Headers(init?.headers);
+        headers.set("Authorization", `Bearer ${params.token}`);
+        return fetch(input, { ...init, headers });
+      };
+      const fetched = await fetchRemoteMedia({
+        url,
+        fetchImpl,
+        filePathHint: file.name,
       });
+      if (fetched.buffer.byteLength > params.maxBytes) continue;
       const saved = await saveMediaBuffer(
-        buffer,
-        contentType ?? file.mimetype,
+        fetched.buffer,
+        fetched.contentType ?? file.mimetype,
         "inbound",
         params.maxBytes,
       );
+      const label = fetched.fileName ?? file.name;
       return {
         path: saved.path,
         contentType: saved.contentType,
-        placeholder: file.name ? `[Slack file: ${file.name}]` : "[Slack file]",
+        placeholder: label ? `[Slack file: ${label}]` : "[Slack file]",
       };
     } catch {
       // Ignore download failures and fall through to the next file.