8TrafficAI Archiving a Reddit post with its media
Reddit stores a post's media in four different shapes, and a naive download gets three of them wrong. This skill handles all four, verified against live posts of each type.
node scripts/rdtx.mjs archive <permalink> --out ./archive --comments 200
Verify the installed runtime without Reddit
Run node scripts/verify-synthetic.mjs with no arguments. It uses fabricated local fixtures to
exercise production media planning—including galleries, video audio metadata, and crosspost-parent
resolution—plus the shared runtime contracts. It makes no Reddit request or download and removes
its temporary state. A pass proves installation and planning behavior only; it does not prove a
live post can be fetched or that media bytes can be downloaded.
Overall passed is the AND of all five shared checks; inspect functional.reddit_archive for this
skill's evidence.
An independent tester can submit the exact named verifier result through the
structured installed-run report.
Select the reddit-archive zero-input synthetic option only after running the installed copy. This
proves installation and media-planning contracts, not a live fetch or downloaded media bytes.
What you get
archive/aww_1varxvd/
├── post.json raw API response, unmodified
├── post.md readable: title, author, age in years, body, nested comments
├── comments.json the full tree
├── media/ image.jpeg | gallery_01..NN.jpeg | video.mp4
└── manifest.json files, sizes, sha256 prefixes, source URLs, media_kind
post.md reports the post's age in years, which is what you want when hunting for old threads.
manifest.json makes the capture reproducible — it records where every byte came from.
The four media shapes, and the trap in each
| type | where the URL lives | the trap |
|---|---|---|
| image | url (i.redd.it/…) |
none — public, no cookies needed |
| gallery | media_metadata[id].s.u |
the signed s= param must be passed whole; truncating it returns 403 |
| video | secure_media.reddit_video |
fallback_url is video-only — taking it silently gives you a clip with no sound |
| crosspost | crosspost_parent_list[0] |
the crosspost itself carries no media; you must follow to the parent |
The video case is the one that bites. Reddit serves v.redd.it as DASH with separate video and
audio streams. archive runs yt-dlp against the permalink and lets ffmpeg merge them, producing
a real h264 + aac file. Verified with ffprobe:
stream: video (h264)
stream: audio (aac)
yt-dlp also refuses Reddit without credentials ("Account authentication is required"), and reading
Chrome's cookie database fails while Chrome holds it open. archive exports a Netscape
cookies.txt from the live browser session instead, which works regardless of locks or keychain.
Requirements
node≥ 18 andagent-browseryt-dlpandffmpeg— needed only for video; images and galleries work without them- a logged-in Chrome session:
rdtx launch→rdtx login→rdtx doctor
Options
| flag | effect |
|---|---|
--out <dir> |
archive root (default ./archive) |
--comments <n> |
how many comments to fetch (default 200) |
--no-media |
metadata and text only |
Verifying a capture
manifest.json records media_kind and a per-file result. A partial capture is visible rather
than silent:
{ "media_kind": "gallery", "comments_captured": 41,
"media": [{ "type": "gallery", "file": "media/gallery_01.jpeg", "bytes": 231460, "ok": true }],
"crossposted_from": null }
If ok is false on any entry, that file did not download — the manifest tells you which and why
instead of leaving a gap you discover later.
Scope and courtesy
This archives public posts through your own logged-in session, at human pace (a jittered wait between requests). It is not a bulk scraper and deliberately has no crawl mode: fetching whole subreddits is what gets IPs and accounts blocked, and Reddit's terms cover bulk collection. For large-scale historical data, use Reddit's own data API or an existing archive dump rather than driving a browser at it.
Related
reddit-post— write posts and commentsreddit-seo— check whether a post is indexable