Crosspost

Distribute content across multiple social platforms with platform-native adaptation.

When to use

• the user wants one message posted to multiple platforms
• publishing announcements, launches, or updates across social media
• repurposing a post from one platform to others
• the user says "crosspost", "post everywhere", "share on all platforms", or "distribute this"

When NOT to use:

• no source post exists yet — author it with content-engine first; this skill distributes, it does not invent
• the job spans landing pages, email sequences, and ads — that is marketing-campaign
• the account credentials are unavailable. Publishing is an external, irreversible write: no credentials means stop, deliver the drafts, and name what is blocked

Inputs

Required before any adaptation — absent input = stop, never guess:

1. Source content — the single core message, plus the primary platform (where the audience is biggest). Its version is drafted first and gets the best treatment.
2. Target platform list + priority order.
3. Credentials / posting surface for each target, and confirmation the account is the right one. For SkyyRose product claims, facts come from wordpress-theme/skyyrose-flagship/data/skyyrose-catalog.csv only.
4. Explicit go-ahead to publish. Posting to a live account is an external write and is irreversible in practice (deletes do not un-see). STOP AND SHOW the exact per-platform text and wait for y before any publish call — one manifest, one y, one send. Approval never carries to the next platform.

Platform specifications

Platform	Max length	Link handling	Hashtags	Media
X	280 chars (4000 Premium)	counted in length	minimal (1–2 max)	images, video, GIFs
LinkedIn	3000 chars	not counted	3–5 relevant	images, video, docs, carousels
Threads	500 chars	separate link attachment	none typical	images, video
Bluesky	300 chars	via facets (rich text)	none (use feeds)	images

Procedure

1. Draft the primary-platform version from the source content (use content-engine patterns).
2. Adapt per platform — write each to its own file so the checks can run:
   • X — hook first, not a summary; cut to the core insight fast; links out of the main body when possible; thread format for longer content.
   • LinkedIn — strong first line (visible before "see more"); short paragraphs with line breaks; framed around lessons, results, professional takeaways; more explicit context than X.
   • Threads — conversational and casual; shorter than LinkedIn, less compressed than X; visual-first where possible.
   • Bluesky — direct and concise inside 300 chars; community-oriented; feeds/lists for topic targeting instead of hashtags.
3. Run the Verification checks on the draft files. Fix anything red before showing the manifest.
4. STOP AND SHOW: print each platform's exact final text and char count, then wait for y.
5. Publish the primary platform first. Capture the post URL for cross-referencing.
6. Publish secondaries, staggered 30–60 minutes, with cross-platform references where useful ("longer thread on X").
7. Verify each post landed: fetch the returned post URL and confirm it resolves.

Attribution: if crossposting someone else's content, credit the source in every version.

Posting surfaces

Native APIs — X API v2 · LinkedIn API v2 (OAuth 2.0) · Threads API (Meta) · Bluesky AT Protocol. A batch service follows this shape, with per-platform bodies never equal:

import os
import requests

resp = requests.post(
    "https://api.postbridge.io/v1/posts",
    headers={"Authorization": f"Bearer {os.environ['POSTBRIDGE_API_KEY']}"},
    json={
        "platforms": ["twitter", "linkedin", "threads"],
        "content": {
            "twitter": {"text": x_version},
            "linkedin": {"text": linkedin_version},
            "threads": {"text": threads_version},
        },
    },
    timeout=30,
)
resp.raise_for_status()

Credentials come from the environment only — never inline a token in a draft or a log line.

Verification

Run every check before the STOP-AND-SHOW manifest, and the live check after publishing. A check that errors (missing draft file → grep/awk exit 2) is a dead gate, not a pass (bug-230).

1. Per-platform length ceiling — over-limit copy is truncated or rejected silently:

awk 'length($0) > 280 {print "OVER-LIMIT line " NR ": " length($0) " chars"; bad=1} END {exit bad}' x.txt

PASS: no output, exit 0. Re-run per platform with its own ceiling (X 280 · Threads 500 · Bluesky 300 · LinkedIn 3000). [repro]

2. No identical copy across platforms — this skill's core rule, made falsifiable:

sort x.txt linkedin.txt threads.txt | uniq -d | grep -v '^[[:space:]]*$'

PASS: no output (final grep exits 1). Any returned line is verbatim on two platforms — rewrite one before the manifest. [repro]

3. The post actually landed — a 200 from the API is not proof the post is visible:

curl -sI "https://x.com/<handle>/status/<id>" | head -1

PASS: HTTP/2 200. A 404 means the publish reported success and did not stick — re-verify by hand rather than trusting the API response. [live]

Check 2 was proven able to fail before being trusted (rule 3): run it once with the same body in two files and confirm the duplicate line is returned; then restore. A SKIP is not a PASS — a platform whose length ceiling was not checked stays unchecked, and the drafter says so in the manifest rather than letting silence read as green.

Worked example

Real run, 2026-07-28, adapting one Black Rose drop message for X and LinkedIn. Drafts written to the session scratchpad.

The first X draft ran 293 chars — over the ceiling, gate red:

$ awk 'length($0) > 280 {print "OVER-LIMIT line " NR ": " length($0) " chars"}' x.txt
OVER-LIMIT line 1: 293 chars

Trimmed to 238 chars, then both gates green:

$ wc -c < x.txt
238
$ awk 'length($0) > 280 {print "OVER-LIMIT line " NR ": " length($0) " chars"; bad=1} END {exit bad}' x.txt && echo "PASS: all lines <= 280"
PASS: all lines <= 280

$ sort x.txt linkedin.txt | uniq -d | grep -v '^[[:space:]]*$'; echo "exit=$?"
exit=1

All outputs observed this session [repro]. Zero shared lines: the X version opens "Black Rose is armor."; the LinkedIn version reframes the same facts as a make-story with an explicit takeaway line. Nothing was published — no credentials were manifested and no y was given, so this run stops at drafts [repro].

Failure modes

Failure	What it looks like	Rule
Identical copy shipped	uniq -d returns shared lines, or was never run	The one rule this skill exists to enforce. Run check 2 on every set
Published without a manifest	posts appear before the user said y	External irreversible write. One manifest → one y → one send; approval never carries to the next platform
Truncated CTA	link or ask cut off by the platform limit	Run check 1 per platform ceiling; links count toward X length, not LinkedIn
API 200 read as "posted"	success response, post not visible	bug-230 fail-open shape. Confirm with check 3 against the real URL [live]; a [repro] API response does not carry a [live] claim
Token leaked into a draft or log	credential visible in output	Environment variables only; never inline, never echo
Hallucinated product claim	invented price, drop date, or SKU	Catalog CSV is the only product manifest — plausible ≠ sourced (bug-096 shape)
Unchecked platform assumed fine	"all platforms verified" after checking one	A SKIP is not a PASS. Name the unchecked platform and who closes it

Related skills

content-engine (authoring the platform-native drafts) · brand-voice (the voice profile) · marketing-campaign (full multi-channel launch). Checked 2026-07-28: no x-api skill is installed in .claude/skills/ or ~/.claude/skills/ [repro] — X publishing means a direct API call, not a skill handoff.