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Summary

When sending documents (PDFs, etc.) via the WhatsApp channel, the file always appears as "file" in the recipient's chat regardless of the actual filename. This is because ⁠ fileName: "file" ⁠ is hardcoded in the Baileys ⁠ sendMessage ⁠ handler's document payload.

Root Cause

Two problems in ⁠ src/web/outbound.ts ⁠ → ⁠ sendMessageWhatsApp() ⁠:

1.⁠ ⁠⁠ loadWebMedia() ⁠ correctly resolves ⁠ media.fileName ⁠ (via ⁠ path.basename(mediaUrl) ⁠), but the fileName is never passed through to ⁠ active.sendMessage() ⁠ — it only passes ⁠ (to, text, mediaBuffer, mediaType) ⁠.

2.⁠ ⁠In the ⁠ sendMessage ⁠ handler (where the Baileys payload is built), the document case hardcodes:
⁠ js
} else payload = {
document: mediaBuffer,
fileName: "file", // ← always "file"
caption: text || void 0,
mimetype: mediaType
};
 ⁠

Fix

1.⁠ ⁠Capture ⁠ media.fileName ⁠ in ⁠ sendMessageWhatsApp ⁠ and pass it through via ⁠ sendOptions ⁠
2.⁠ ⁠Use ⁠ sendOptions?.fileName || "file" ⁠ in the document payload instead of hardcoded ⁠ "file" ⁠

Affected code paths

The hardcoded ⁠ fileName: "file" ⁠ appears in the ⁠ sendMessage ⁠ handler which is bundled into 4 dist files:
•⁠ ⁠⁠ pi-embedded-.js ⁠
•⁠ ⁠⁠ reply-.js ⁠
•⁠ ⁠⁠ extensionAPI.js ⁠
•⁠ ⁠⁠ loader-*.js ⁠

Note

Inbound filename handling was already fixed (per CHANGELOG: "preserve original filenames for inbound documents"), but the outbound side was missed.