refactor(worker): promote ranged-listing dispatcher to a shared module

worker/src/archive/ranged/dispatch.test.ts

@@ -0,0 +1,15 @@
+import { describe, it, expect } from "vitest";
+import { readScannedListingRanged } from "./dispatch.js";
+
+describe("readScannedListingRanged", () => {
+  it("returns null for an unknown archive type without calling the reader", async () => {
+    const read = async () => Buffer.alloc(0);
+    const result = await readScannedListingRanged(
+      "DOCUMENT",
+      { invoke: async () => ({}) } as never,
+      [{ fileId: "1", fileSize: 100n, fileName: "a.pdf" }],
+    );
+    expect(result).toBeNull();
+    void read; // unused placeholder kept out of the dispatch call — DOCUMENT never reaches a reader
+  });
+});

worker/src/archive/ranged/dispatch.ts

@@ -0,0 +1,62 @@
+import type { Client } from "tdl";
+import { downloadFileRange } from "../../tdlib/range-download.js";
+import { parseZipCentralDirectoryFromTail, MIN_ZIP_TAIL_BYTES } from "../central-directory.js";
+import { childLogger } from "../../util/logger.js";
+import type { FileEntry } from "../zip-reader.js";
+import { readSevenZListingRanged, type RangedPart } from "./sevenz-ranged.js";
+import { readRarListingRanged } from "./rar-ranged.js";
+import { tdlibRangeReader } from "./range-reader.js";
+
+const log = childLogger("ranged-dispatch");
+
+/**
+ * Read a ZIP central directory from the tail of a (possibly multipart)
+ * archive. `parts` is ordered; only the LAST part carries the EOCD record.
+ * `fileSize` on each part is that part's own size (NOT the whole-archive
+ * total) so the download offset stays within that part's bounds, while
+ * `tailStart` passed to the parser is the logical whole-archive offset
+ * (preceding parts' sizes + the offset within the last part).
+ */
+export async function readScannedZipListing(
+  client: Client,
+  parts: { fileId: string; fileSize: bigint }[],
+): Promise<FileEntry[] | null> {
+  if (parts.length === 0) return null;
+  const lastPart = parts[parts.length - 1];
+  const precedingSize = parts.slice(0, -1).reduce((sum, p) => sum + Number(p.fileSize), 0);
+  const lastSize = Number(lastPart.fileSize);
+  for (const tailBytes of [MIN_ZIP_TAIL_BYTES, MIN_ZIP_TAIL_BYTES * 4]) {
+    const partOffset = Math.max(0, lastSize - tailBytes);
+    const downloadLen = Math.min(tailBytes, lastSize);
+    try {
+      const buf = await downloadFileRange(client, lastPart.fileId, partOffset, downloadLen, lastPart.fileSize);
+      const tailStart = precedingSize + partOffset;
+      return parseZipCentralDirectoryFromTail(buf, tailStart);
+    } catch (err) {
+      if (err instanceof RangeError) continue; // try a larger tail
+      log.warn({ err, fileId: lastPart.fileId }, "ranged ZIP listing failed");
+      return null;
+    }
+  }
+  return null;
+}
+
+/**
+ * Dispatch a (no-download) inner-file listing read by archive type. Used both
+ * by the provenance-backfill path (reading an already-uploaded copy) and the
+ * forward-priority ingestion path (reading the source channel's copy before
+ * any download/forward decision is made) — the read itself only needs
+ * {fileId, fileSize, fileName}, so it doesn't matter which channel the file
+ * currently lives in.
+ */
+export async function readScannedListingRanged(
+  archiveType: string,
+  client: Client,
+  parts: RangedPart[],
+): Promise<FileEntry[] | null> {
+  const read = tdlibRangeReader(client);
+  if (archiveType === "ZIP") return readScannedZipListing(client, parts);
+  if (archiveType === "SEVEN_Z") return readSevenZListingRanged(parts, read);
+  if (archiveType === "RAR") return readRarListingRanged(parts, read);
+  return null;
+}

worker/src/provenance-backfill.ts

@@ -1,8 +1,6 @@
 import { db } from "./db/client.js";
 import { childLogger } from "./util/logger.js";
-import { downloadFileRange } from "./tdlib/range-download.js";
 import { invokeWithTimeout } from "./tdlib/download.js";
-import { parseZipCentralDirectoryFromTail, MIN_ZIP_TAIL_BYTES } from "./archive/central-directory.js";
 import { fingerprintsMatch, crcFingerprint } from "./archive/fingerprint.js";
 import {
   findPlaceholderCandidates,
@@ -15,6 +13,7 @@ import { readSevenZListingRanged, type RangedPart } from "./archive/ranged/seven
 import { readRarListingRanged } from "./archive/ranged/rar-ranged.js";
 import { tdlibRangeReader } from "./archive/ranged/range-reader.js";
 import { fullDownloadListing } from "./archive/ranged/fallback.js";
+import { readScannedZipListing, readScannedListingRanged } from "./archive/ranged/dispatch.js";
 import type { Client } from "tdl";
 
 const log = childLogger("provenance-backfill");
@@ -36,38 +35,6 @@ export interface BackfillArgs {
   previewMsgId?: bigint | null;
 }
 
-/**
- * Read a ZIP central directory from the tail of a (possibly multipart)
- * archive. `parts` is ordered; only the LAST part carries the EOCD record.
- * `fileSize` on each part is that part's own size (NOT the whole-archive
- * total) so the download offset stays within that part's bounds, while
- * `tailStart` passed to the parser is the logical whole-archive offset
- * (preceding parts' sizes + the offset within the last part).
- */
-async function readScannedZipListing(
-  client: Client,
-  parts: { fileId: string; fileSize: bigint }[],
-): Promise<FileEntry[] | null> {
-  if (parts.length === 0) return null;
-  const lastPart = parts[parts.length - 1];
-  const precedingSize = parts.slice(0, -1).reduce((sum, p) => sum + Number(p.fileSize), 0);
-  const lastSize = Number(lastPart.fileSize);
-  for (const tailBytes of [MIN_ZIP_TAIL_BYTES, MIN_ZIP_TAIL_BYTES * 4]) {
-    const partOffset = Math.max(0, lastSize - tailBytes);
-    const downloadLen = Math.min(tailBytes, lastSize);
-    try {
-      const buf = await downloadFileRange(client, lastPart.fileId, partOffset, downloadLen, lastPart.fileSize);
-      const tailStart = precedingSize + partOffset;
-      return parseZipCentralDirectoryFromTail(buf, tailStart);
-    } catch (err) {
-      if (err instanceof RangeError) continue; // try a larger tail
-      log.warn({ err, fileId: lastPart.fileId }, "ranged ZIP listing failed");
-      return null;
-    }
-  }
-  return null;
-}
-
 /**
  * Resolve the destination copy's message(s) into ranged parts (file id +
  * size + name), in order, so a multipart destination copy is reconstructed
@@ -106,18 +73,6 @@ async function resolveDestParts(
   }
 }
 
-async function readScannedListingRanged(
-  archiveType: string,
-  client: Client,
-  parts: RangedPart[],
-): Promise<FileEntry[] | null> {
-  const read = tdlibRangeReader(client);
-  if (archiveType === "ZIP") return readScannedZipListing(client, parts);
-  if (archiveType === "SEVEN_Z") return readSevenZListingRanged(parts, read);
-  if (archiveType === "RAR") return readRarListingRanged(parts, read);
-  return null;
-}
-
 /**
  * Build the CRC fingerprint entries for a placeholder candidate: start from
  * its stored PackageFile CRCs, and if those are incomplete (e.g. a rebuild