| name | reddit-post |
| description | Post and comment on Reddit from an agent, through the user's own logged-in Chrome, and verify the submission actually survived moderation instead of trusting the HTTP 200. Use whenever someone wants to post to Reddit, submit a thread, leave a comment, reply to a thread, publish to a subreddit, or automate Reddit posting from a script or agent — including phrasings like "post this to r/X", "reply to this Reddit thread", "draft and publish a Reddit post". Also use when a Reddit write is failing: 403 errors, a "Prove your humanity" interstitial, an expired session, a flair-required rejection, or a post that returned success but is missing from the subreddit. This skill contains the diagnosis path for all of those. Single account only — the user's own. Not for read-only Reddit research, and not for operating multiple accounts.
|
Posting to Reddit from an agent
Reddit writes fail for agents in ways that look like bugs but aren't. The naive approaches — a
scripted HTTP client, or Playwright/Puppeteer launching its own browser — hit walls no amount of
retry logic fixes. Understanding why saves a long debugging spiral.
The architecture, and why
rdtx attaches over CDP to a Chrome the human launched, and issues writes as same-origin
fetch calls from inside the logged-in page. Three measured facts make that the right shape;
references/browser-session.md has the evidence.
The automation flag is set at launch, not by attaching. Puppeteer and Playwright pass
--enable-automation, setting navigator.webdriver = true. Start Chrome with only
--remote-debugging-port and attach afterwards, and it stays false.
"Prove your humanity" is transient. It's a JS proof-of-work that self-resolves in seconds, not
a block. rdtx polls through it. Concluding you've been blocked is the most common way to abandon
a working setup.
Let the page build the request. Writes reuse Reddit's own cookies and CSRF material verbatim,
so there's no auth protocol to reimplement or keep in sync.
Setup, once
Live commands require Node.js 18+, agent-browser, and the user's own logged-in Chrome profile;
see references/browser-session.md. The synthetic verifier needs only Node.js 18+.
node scripts/rdtx.mjs launch
node scripts/rdtx.mjs login
node scripts/rdtx.mjs doctor
rdtx never handles the password. doctor reports each layer independently, so a failure tells
you which one broke.
Verify the installed runtime without Reddit
Run node scripts/verify-synthetic.mjs with no arguments. It starts the production submit CLI
without --yes, checks the real temporary audit entry and both remote_checks, and arms guards
that fail if the CLI tries to reach a network or agent-browser. It also exercises the other
shared Reddit contracts with fabricated fixtures. A pass proves the local dry-run boundary only;
it does not authorize or prove a real Reddit write.
Overall passed is the AND of all five shared checks; inspect functional.reddit_post for this
skill's evidence.
An independent tester can submit the exact named verifier result through the
structured installed-run report.
Select the reddit-post zero-input synthetic option only after running the installed copy. This
proves installation and local contract behavior, not a live Reddit write.
Commands
| command | what it does | writes? |
|---|
doctor / launch / login | session setup and diagnosis | no |
requirements <sub> | flair, rules, gates — check before posting | no |
read <permalink> | post + comments + visibility state | no |
submit <sub> <title> --text|--url | create a post | yes |
comment <permalink|tN_id> <text> | comment or reply | yes |
me / inbox | karma totals, replies and mentions | no |
audit | every write attempted or executed | no |
Every write is a dry run unless you pass --yes
node scripts/rdtx.mjs submit test "My title" --text "Body"
node scripts/rdtx.mjs submit test "My title" --text "Body" --yes
An agent composing a post will often run the command just to inspect the payload. A tool that
posts on first invocation turns that into a public, hard-to-undo action. The dry run returns the
requested payload so the subreddit, title, body, URL, and requested flair can be confirmed before
anything leaves the machine. It is fully local: no browser command or Reddit request is made, and
both entries in plan.remote_checks report not_run. Both dry runs and real writes append to
~/.rdtx/audit.jsonl with executed: true|false.
Flair is required in most large subreddits
node scripts/rdtx.mjs submit ClaudeAI "Title" --text "Body" --flair "Skills" --yes
After explicit --yes confirmation, submit resolves flair by name and checks
is_flair_required before the write request, so a missing flair fails before Reddit creates a
post. A wrong name returns the subreddit's actual flair list. The default dry run deliberately
does not perform either remote check; it reports the requested flair for review instead.
A 200 is not proof — this is the part people miss
Large subreddits route new posts through AutoMod, where they sit reachable by direct link but
absent from listings and marked non-indexable. The write returns 200 and reads back perfectly.
Measured on a real post, minutes apart, before and after a moderator approved it:
removed_by_category: "automod_filtered" → null
is_robot_indexable: false → true
submit re-reads after writing and reports the result:
"visibility": { "state": "automod_filtered", "public": false, "indexable": false }
States are live, automod_filtered, not_indexable, removed. Treat anything other than live
as not published yet, and wait rather than reposting — reposting to escape a filter converts
one filtered post into a spam pattern across the account. Pass --no-verify to skip the check.
Image posts
Image upload works, but only through a trusted path. Two things had to be true, and both were
found by failing first:
Synthetic events are ignored. Setting input.files from page JavaScript sticks on the element
and shreddit's Lit component never reacts; a dispatched DragEvent is ignored the same way. The
API route is closed too — /api/media/asset.json 403s under modhash, X-CSRF-Token, a
csrf_token field, and all combinations. What works is DOM.setFileInputFiles over CDP, which the
page cannot distinguish from a human choosing a file.
Most of the file inputs are decoys. The composer keeps ~7 mounted at once as placeholders for
the other post types, and setFileInputFiles succeeds silently against the inert ones — the
command returning is not evidence of anything. Only the input with accept="image/*" actually
holds the file. image-post.mjs sweeps every candidate and keeps whichever ends up non-empty.
node scripts/image-post.mjs test "My title" --image ./a.png,./b.png
node scripts/image-post.mjs test "My title" --image ./a.png --flair "Skill Share" --yes
Title goes in via Input.insertText after a real Input.dispatchMouseEvent click, and Post is
clicked at its measured coordinates — all trusted, all through Reddit's own composer, so there is
no write protocol to reimplement.
Gotcha: Reddit persists composer drafts. Images staged in an earlier session are still there
when you navigate back, so a post can go out with more images than you passed. Check the returned
n against what you supplied, or clear the draft first.
Image link posts remain available and need none of this — submit --url <image-url> renders
with a preview.
Choosing a target when testing
Use r/test or the user's own profile subreddit (u_<username>). Both exist for this and affect
no community. Proving a setup against a real topical subreddit spends the user's account standing
on a smoke test.
Pacing
A jittered ~2.3–8s wait precedes each write, keeping you inside Reddit's rate limits. For many
writes, spread them out rather than removing the pacing — Reddit's "You are doing that too much"
costs more time than the waits.
Scope
One account — the user's own. No multi-account, proxy-rotation, or fingerprint-spoofing
support, and none is planned: that targets platform integrity detection rather than getting your
own posting to work, and Reddit's terms prohibit it. If a task seems to need several accounts
looking like unrelated people, raise it with the user rather than engineering around it.
Troubleshooting
| symptom | cause | fix |
|---|
cdp_reachable: false | Chrome not started with a debug port | rdtx launch |
| title is "Prove your humanity" | transient JS challenge | wait — settle() retries |
logged_in: false but status 200 | session expired; an exported cookie file rots in ~a day | rdtx login |
flair_required error | subreddit demands flair | --flair "<text>" |
| 200 but missing from the subreddit | AutoMod filtered it | check visibility; wait for a mod |
errors: [["RATELIMIT", …]] | posting too fast | wait the stated interval |
Related
reddit-seo — audit whether existing posts are indexablereddit-archive — capture a post with its media
