Draft social-media posts for LinkedIn, Hacker News, Twitter/X, Reddit, Threads,
Facebook, Instagram, Mastodon, Bluesky, and Dev.to. Each draft is staged in an
Aside browser tab (signed-in persistent session), screenshotted, and surfaced
for human review. Posts ONLY go live after the user types "POST APPROVED"
(per-platform allowed: "POST APPROVED linkedin,hackernews"). Pure draft mode by
default — no LLM augmentation, no auto-post, no exceptions.
Standardmäßig ist der Prompt ausgewählt, der zuerst die Quelle prüft. Sie können zu einem direkten Befehl wechseln oder eine lokale Kopie herunterladen.
Quelldateien prüfen
Lesen Sie SKILL.md und alle von SkillsMP angezeigten Begleitdateien, bevor Sie sich für eine Installation entscheiden.
Mit Codex oder Claude installieren Kopieren Sie diesen Prompt, fügen Sie ihn in Codex, Claude oder einen anderen Assistant ein und lassen Sie die Skill-Seite prüfen und installieren.
Ein direkter Befehl überspringt den Prüf-Prompt. Prüfen Sie die Quelle, bevor Sie ihn ausführen.
Draft social-media posts for LinkedIn, Hacker News, Twitter/X, Reddit, Threads,
Facebook, Instagram, Mastodon, Bluesky, and Dev.to. Each draft is staged in an
Aside browser tab (signed-in persistent session), screenshotted, and surfaced
for human review. Posts ONLY go live after the user types "POST APPROVED"
(per-platform allowed: "POST APPROVED linkedin,hackernews"). Pure draft mode by
default — no LLM augmentation, no auto-post, no exceptions.
when_to_use
Use when the user asks to draft a post for any social platform, share a project
on LinkedIn/HN/Twitter, post to Reddit, prepare a Show HN, draft an Instagram
caption, or any "draft a post" / "post to <platform>" / "share on social" /
"/social <intent>" request. Also fires on "/social <intent>" slash command.
allowed-tools
["Read","Write","Bash","Edit","Grep"]
triggers
["draft a social post","draft a post","post to social","post to linkedin","post to hacker news","post to reddit","post to twitter","post to threads","post to facebook","post to instagram","draft linkedin post","draft hacker news post","draft reddit post","draft tweet","draft twitter thread","draft instagram caption","draft threads post","show hn","social poster","/social"]
context
inline
Social Poster — Draft-Only, POST APPROVED Gated
Contract
Draft, never post — default mode produces text files + browser-staged tabs + screenshots. No network mutation without explicit POST APPROVED.
Persistent browser session — uses aside CLI (signed into $USER@gmail.com) to keep one session across multiple platform tabs; never spawns a fresh Playwright Chromium per platform.
Per-platform conformance — character limits, title rules, hashtag placement, threading, self-promo ratios checked at draft time (no "fix it after posting").
Reddit 10/90 + per-sub rules — every Reddit draft is checked against the live-verified rules in references/subreddit-rules.md (r/LocalLLaMA, r/Rag, r/OpenAI verified via Aside probe 2026-07-05).
POST APPROVED token — scripts/post_approved.py checks for literal POST APPROVED (or per-platform like POST APPROVED linkedin,hackernews) before clicking any submit button. Without the token, exits code 2 with "BLOCKED — no POST APPROVED token".
No LLM augmentation by default — pure templating. To enable LLM refinement, pass --use-llm (which routes through your existing ~/.hermes/config.yaml auxiliary provider; never hardcodes API keys).
Auto-stage on /social — when invoked as /social <intent>, run Phase 1 + Phase 2 back-to-back without asking. The user invoked the command → staging is implied. (Jeffrey preference, 2026-07-17: "stage it and next time stage without asking".) Skip staging ONLY if Aside extension bridge is down or all drafts are intentionally login-wall / load_only / no_recipe.
Supported Platforms
Platform
Template
Has web compose?
Notes
LinkedIn
templates/linkedin.md
✅
long-form + 300-char short variant
Hacker News
templates/hackernews.md
✅
"Show HN:" prefix when self-promo; title ≤80 chars
Twitter/X
templates/twitter.md
✅
single tweet + thread; hashtags at end of last tweet only
Reddit
templates/reddit.md
✅
one file per subreddit; text-post preferred over link-post
Threads
templates/threads.md
✅
≤500 chars, casual
Facebook
templates/facebook.md
✅
medium-length, link-friendly
Instagram
templates/instagram.md
⚠️ no web compose
caption + 30-hashtag block; surfaces mobile instructions
Mastodon
templates/mastodon.md
✅
500-char default; configurable instance
Dev.to
templates/devto.md
✅
markdown article format
Phases
Phase 1 — Draft (deterministic, no browser)
Run scripts/draft_social_post.py with intent + key-points + link + platforms. Produces per-platform files in --out <dir>. Character-limit hard-rejects; spam-rule soft-warns.
Output: one .md file per platform (or per subreddit for Reddit). Filename-safe slugs.
Phase 2 — Stage in Aside (browser, no auto-post)
Prefer the MCP path (stage_in_aside_mcp.py) when available. The aside repl CLI silently no-ops on programmatic paste (lesson #11; verified 2026-07-17 across 9/11 platforms failed despite "compose-ready" status). The HTTP MCP at 127.0.0.1:8013/mcp with openTab() + Playwright locator().fill() reliably pastes when the session is healthy.
PY=$HOME/.hermes/skills/social-poster/scripts/stage_in_aside_mcp.py
python3 "$PY" --drafts /tmp/drafts/social-2026-07-17/
# allowlist sub-stage, e.g. only HN + Twitter for retry runs:
python3 "$PY" --drafts /tmp/drafts/social-2026-07-17/ --only hackernews,twitter
Falls back to the legacy aside repl script when MCP is unreachable:
exec_command — contentEditable (Twitter, LinkedIn, Facebook, Threads); uses document.execCommand('insertText', false, text) after el.focus() — the only reliable pattern for React-controlled contentEditable fields.
Reads the field back with verify_text(selector) and compares against expected draft length (≥70% threshold to allow for trailing whitespace stripping).
The script will NOT claim a platform is "ready" unless the draft text was verified inside the field. Vision-verify at least one screenshot per platform after staging for a final cross-check.
Aside recipes for each platform's compose URL live in references/aside-recipes.md.
Phase 3 — Surface to user
Print all draft file paths + screenshot paths. Attach screenshots via Slack MEDIA:/path (per evidence-attach-to-slack skill). Ask: "POST APPROVED?"
Phase 4 — Post (gated)
ONLY after the user types POST APPROVED (literal, case-insensitive, optionally with comma-separated platform allowlist), run:
PY=$HOME/.hermes/skills/social-poster/scripts/post_approved.py
python3 "$PY" \
--drafts /tmp/drafts/social-2026-07-06/ \
--approval-token "POST APPROVED" \
[--platforms linkedin,hackernews] # if omitted, posts all staged
❌ Hardcoding API keys in draft_social_post.py (LLM augmentation must route through ~/.hermes/config.yaml)
❌ Stripping 10/90 framing from Reddit drafts ("I built this, here's the link") — guarantees removal
❌ Posting the same draft verbatim across Reddit subs (each sub has different norms; per-sub files required)
❌ Posting link-only to r/OpenAI — requires text post + context (verified rule)
❌ Clicking submit in Phase 2 (stage-only)
❌ Treating draft_social_post.py output as final without reading it — the templater hallucinates key-points into the wrong slots when the intent is a commentary/opinion piece rather than a project announcement (e.g. "Fable AI oneshot a 2D game" gets turned into "jleechanclaw does X"). Always read every generated .md file before staging. If templating misfires, hand-author the drafts directly (write .md files in --out) and re-run staging on the hand-authored files. Worked example: references/fable-2d-game-2026-07-11.md.
❌ Trusting stage_in_aside.py's "compose-ready" DOM verdict without vision-verification. The script's DOM-detector only checks for selectors like input[name="title"]; it does NOT verify that the text was actually pasted into the field. Programmatic paste via React setter / contentEditable frequently fails silently on Twitter, LinkedIn, HN, and Reddit modals. After every staging run, vision-verify AT LEAST ONE screenshot per platform (vision_analyze("Is the draft text visible in the compose field, or is it empty?")). If empty, the compose form is loaded but paste didn't stick — user must paste manually from the .md files.
❌ Trusting listBrowserTabs() as proof the platform is signed in — it proves the tab is signed in, but openTab(compose-url) may still hit a session-revalidation redirect to a login wall (LinkedIn, Facebook, Dev.to, Mastodon, Threads all did this on 2026-07-11). The source-of-truth check is: vision-verify the staged screenshot shows a compose form with user avatar/handle visible, NOT a login wall.
❌ Staging a Twitter draft that exceeds 280 chars (verified 2026-07-17). The compose modal accepts arbitrary input but disables the Post button (red highlight + "-666" counter visible) once the limit is exceeded. The drafter must keep single-tweet drafts ≤280 chars; longer content needs a --thread flag that splits into N tweets. The default templates/twitter.md does NOT enforce this — check after drafting.
❌ Splitting the staging workflow across multiple MCP tools/call invocations (verified 2026-07-17). See lesson 19 — each openTab opens a fresh tab, so call 2's paste lands on a different form instance than call 1's open. Always bundle (openTab → fill → verify → screenshot) in ONE IIFE per platform.
When LinkedIn staging returns a "Welcome back" password screen, do NOT conclude LinkedIn is unreachable. Check for these one-click unblock signals in the screenshot before declaring the platform blocked:
Google One-Tap prompt (top-right overlay, dark gray box, "Sign in to LinkedIn with Google" + blue "Continue as Jeffrey" button) — one click unblocks the session.
Continue with Google button (white button below "Sign in" with Google G logo) — same OAuth flow, one click.
Sign in with Apple button — same UX as Google.
If any of these are visible AND the email shown matches $USER@your-project.com, the user can unblock LinkedIn in 1-2 clicks. Tell them which button to click.
If NO unblock signal is visible (just an empty password field), the session is fully expired and the user must type their password.
Output Format
After Phase 3, the skill reply includes:
## social-poster draft ready
- Drafted: 9 platforms (linkedin, hackernews, twitter, reddit x3, threads, facebook, instagram, mastodon, devto)
- Staged: 9 Aside tabs open (URLs: …)
- Screenshots: /tmp/drafts/social-2026-07-06/screenshots/ (9 PNGs)
- Manifest: /tmp/drafts/social-2026-07-06/manifest.json
**To post:** reply with `POST APPROVED` (all) or `POST APPROVED <platforms>`.
**To revise:** tell me what to change and I'll re-draft + re-stage.
Screenshots attached via MEDIA:/path/to/png for inline Slack preview.
Trigger → Action Map
User says
Action
draft a post about X
Phase 1 only
draft + stage a post about X
Phase 1 + Phase 2
POST APPROVED
Phase 4 (all staged)
POST APPROVED linkedin,twitter
Phase 4 (only those two)
revise the linkedin draft
Re-run Phase 1 + Phase 2 for that platform only
cancel drafts
Close Aside tabs, keep files
draft posts for <LinkedIn/Twitter URL>
Commentary-source path: extract source body via curl + og:description regex (NOT web_extract), hand-author drafts (template misfires on commentary), see references/fable-2d-game-2026-07-11.md
Phase 3.5 — Posting the user-facing summary (Slack/Discord), MCP-down aware
The draft summary message to the user can land on Slack/Discord/chat. When the messaging MCP is available, use it. When mcp__slack__conversations_add_message returns not_in_channel or the server reports "unreachable after N consecutive failures", fall back to the user's XOX-P (user token) via curl (per SOUL.md slack-cross-workspace-fallback-xoxp):
The XOX-P fallback posts as the user (not the Hermes bot identity). Say so in the body if it might confuse the user. Do NOT stall with "iteration budget exhausted" — the post still goes through. After the fallback, continue with the standard "POST APPROVED?" prompt.
For non-Slack chat (Discord/Telegram/Discord DM/etc.) the same fallback pattern applies: curl to the platform's REST endpoint with the user token rather than waiting for the MCP to recover.
scripts/stage_in_aside_mcp.py — preferred: opens Aside tabs + pastes via HTTP MCP at 127.0.0.1:8013/mcp. One MCP call per platform bundles open + paste + verify + screenshot on a single page object (avoiding the "fresh tab = lost paste" failure). Verified selectors for HN, Twitter, Mastodon, Reddit ×3, Dev.to, LinkedIn, Facebook, Threads (2026-07-17).
scripts/cookie_inject_and_stage.py — uses browserclaw cookies decrypt + Playwright Chrome with injected cookies to stage + paste drafts (for platforms where Aside is not signed in)
references/platform-character-limits.md — hard limits + soft guidance
references/aside-recipes.md — aside repl snippets per platform
references/platform-session-status.md — per-platform cookie injection + anti-bot results (verified 2026-07-05). Playwright Chrome only — see aside-repl-session-state.md for aside repl-based staging.
references/blog-post-to-gdoc.md — recipe for "draft a blog post in Google Docs" (canonical gws docs path + local-markdown fallback when gws OAuth is unauthenticated).
references/aside-repl-session-state.md — verified auth state per platform for aside repl workflows (2026-07-06). Includes the listBrowserTabs() live-tab probe recipe, the document scope-doesn't-persist-across-REPL-calls pitfall, and per-platform paste workarounds for LinkedIn contentEditable / Facebook click-first / Twitter thread pagination.
references/aside-repl-playwright-pattern.md — verified openTab() returns a Playwright Page object with screenshot() (Buffer→base64), evaluate(), locator(), frameLocator(). Includes 6 working paste/click/inspect idioms. Source of truth for the 2026-07-06 staging rewrite.
references/fable-2d-game-2026-07-11.md — worked example for commentary/opinion drafts (NOT project announcements). Documents the Fable 2D-game run, the templater failure mode, the vision-verify matrix, and the recommended workflow for future commentary runs.
references/fable-quota-skill-2026-07-15.md — worked example for commentary/opinion about a third-party capability + a personal artifact (gist/skills). Documents lessons 15 (require('fs') is not in the REPL; capture screenshots via base64 stdout redirect), 16 (Mastodon URLs: /compose is 404, use /publish), and 17 (LinkedIn share-box trigger has obfuscated classes; programmatic click fails). Also documents the Phase 3.5 MCP-down fallback for posting the summary via XOX-P curl when mcp__slack__conversations_add_message is unreachable.
tests/test_*.py — unit + integration tests
references/staged-vs-pasted-verification.md — CRITICAL: how to verify drafts actually got pasted into compose forms (vs. just having the page loaded). Use the explicit "what text is in the field?" vision prompt + the verification snippet. The stage script's staged: True is not enough.
references/aside-mcp-cli-gmail-profile.md — Aside automation via HTTP MCP at 127.0.0.1:8013/mcp with mcp-session-id header flow + gmail (u0) profile. Reusable Python client snippet. The most reliable automation path when the Chrome extension bridge is alive. Includes the verified openTab + locator.fill() + screenshot pipeline, per-platform selector table for HN / Twitter / Mastodon / Reddit / Dev.to / LinkedIn / Facebook / Threads, and 7 stage pitfalls (MCP degradation, Reddit fragility, login walls, subprocess.run vs Popen) verified 2026-07-17.
Operator preferences (captured 2026-07-11)
Jeffrey's standing directives for this skill — embed these in any automation flow:
Headless only. Never open a visible browser window. Use browserclaw cookies inject --headless or headless Playwright (p.chromium.launch(headless=True)). If a step would spawn a GUI window (e.g. open -a "Aside" or aside "Open X" without headless mode), prefer the headless equivalent or surface the limitation rather than opening the GUI.
Use /browserclaw to copy Chrome cookies as needed. Cookies are the persistent auth substrate; decrypt them from the local Chrome / Aside cookie DB rather than asking the user to log in or paste tokens. If browserclaw CLI is broken (see browserclaw SKILL.md broken-editable-install pitfall), fall back to hand-loading the Playwright storage_state JSON written by a previous successful decrypt.
POST APPROVED gating is mandatory. No auto-post, no scheduled post, no background post. The literal token POST APPROVED (optionally POST APPROVED <platforms>) must appear in the current session before any submit/click-post action.
Vision-verify, don't DOM-detect. The script's DOM verdict and the actual field contents can disagree — programmatic paste via React setter / contentEditable frequently fails silently. After every staging run, vision-verify at least one screenshot per platform with the explicit question "What text is currently inside the compose field?" before claiming the platform is "ready".
Critical lessons (from real sessions, not theoretical)
staged ≠ pasted. The stage_in_aside.py script labels every successfully-navigated compose form as "staged" even when the paste silently failed (React-controlled-field re-render ate the programmatic input). Vision-verify the actual TEXT inside the title input + body textarea, not just the page state. A logged-in compose form with empty fields looks identical to a logged-in compose form with empty fields — vision models will say "compose form ready" either way unless explicitly asked "what text is currently inside the field?" (lesson from 2026-07-11 Fable-2D-game run, user pushback: "all of those drafts are obviously wrong and just random login screens so youre not even close to working"). See references/staged-vs-pasted-verification.md for the verify-paste checklist + reusable paste verification snippet.
0a. Use --account u0 ($USER@gmail.com) for aside repl automation. Default active is u1 (your-project.com) and the extension bridge can be more brittle on that profile. Verified 2026-07-11 — user pushed "use $USER@gmail.com profile next time and use the mcp or cli its supposed dto work". See references/aside-mcp-cli-gmail-profile.md.
0b. Aside HTTP MCP at 127.0.0.1:8013/mcp is the most reliable automation path (when the extension bridge is alive). Tools surface: just repl (single tool wrapping the persistent JS REPL). MCP initialize handshake requires reading the mcp-session-id header from the response and sending it on subsequent calls + notifications/initialized. Top-level await is NOT allowed in the REPL — wrap in (async () => { ... })();. The REPL has persistent scope (vars persist across calls), fs module via node:fs/promises, display() for inline image preview, sleep(ms), fetch() with user cookies. See references/aside-mcp-cli-gmail-profile.md for the full request flow + reusable client snippet.
aside account list does NOT show per-platform auth state. It only shows the active Google account ID. To gauge whether LinkedIn/Twitter/Facebook/etc. are actually signed in, run aside repl "const tabs = await listBrowserTabs(); console.log(tabs.map(t => t.url).join(' | '))". A signed-in tab on the platform = the session is valid, even if a fresh openTab(compose-url) shows a login wall (compose-URL navigation may trigger session re-auth).
document scope does NOT persist across aside repl calls. Each call gets a fresh JS context. Multi-step workflows (open → click → paste → verify) must be bundled in ONE async IIFE in a single call. Screenshot via annotatedScreenshot(pageObj) returned from openTab(), not annotatedScreenshot(null).
Programmatic paste into LinkedIn/Twitter/Facebook compose modals is unreliable. Twitter's textarea + React setter trick works in a single bundled call. LinkedIn's contentEditable div + el.innerHTML = text works but React state may not sync (manual paste is more reliable). Facebook requires click-first on "What's on your mind, [Name]?" before the modal opens. Default workflow: stage + screenshot the empty compose area, let the user paste manually. This avoids the React control gymnastics entirely and the user still gets visual proof the compose UI is loaded.
POST APPROVED is mandatory for any submit/click-post action. Drafts may be staged freely. Posting requires the literal POST APPROVED string (optionally with comma-separated platform allowlist). No exceptions, no "looks approved" heuristics. See scripts/post_approved.pycheck_approval() for the gate logic.
aside session ≠ account list ≠ Chrome cookie DB. The source of truth is listBrowserTabs(). If the user says "I'm signed in to LinkedIn", verify with that probe before declaring a platform unreachable.
openTab(url) returns a Playwright Page object, not a serializable tab descriptor. Use p.screenshot() directly (returns a Buffer that base64-encodes for stdout), or p.locator(...) / p.evaluate(() => ...) for DOM ops. annotatedScreenshot(null) throws Cannot read properties of null (reading 'snapshot'); annotatedScreenshot(pageObj) works but p.screenshot() is simpler. See references/aside-repl-playwright-pattern.md for the verified idioms.
Reddit compose URL must end in ?selftext=true.https://old.reddit.com/r/<sub>/submit lands on the link-post form by default, which navigates through the "link vs text" tab UI and triggers a session re-auth redirect. The ?selftext=true param lands directly on the text-post form with title (textarea[name="title"]) + body (textarea[name="text"]) fields visible. stage_in_aside.py's compose URL for Reddit MUST include this param. Verified 2026-07-06 for r/LocalLLaMA, r/OpenAI, r/Rag — all three compose forms loaded immediately with no auth redirect when the ?selftext=true suffix was used.
Vision-verify compose-vs-login, don't DOM-detect. A DOM-only check like document.querySelector('input[name="title"]') can give false negatives if the page is still loading. The deterministic check is p.screenshot() → save → vision_analyze(image_url, "Is the compose form for posting to r/X visible, with title input and body textarea? Or is it a login wall?"). The user said "Many of these screenshots are login screens I wanna find the draft post screen / Still not good enough" on 2026-07-06 — the lesson: ALWAYS confirm by vision, never trust URL or DOM-only state when the user wants visual proof.
Aside daemon restart = sessions break. If aside repl returns "fetch failed" and you pkill -f AsideDaemon to recover, all open tabs are lost. Subsequent openTab() calls hit login walls even though the underlying Chrome cookie DB still has valid sessions, because Aside's tab-object state is gone. listBrowserTabs() returns TOTAL_TABS 1 (a single fresh tab) instead of the prior 17-tab state. Fix: instead of pkill, try open -a "Aside" first — sometimes the daemon recovers without losing tabs. If you must restart, plan for a sign-in re-pass on platforms that were "previously signed in."
draft_social_post.py cannot tell a project announcement from a commentary/opinion piece. When the source URL is a personal reaction to a third-party capability (e.g. "Fable AI oneshot a 2D game from my text sim"), the templater will hallucinate the user's open-source project as the subject and stuff every key-point into the wrong slot. Always read every generated .md before staging. If misfires, hand-author directly into the same files. Worked example: references/fable-2d-game-2026-07-11.md.
Compose-ready ≠ paste-stuck (re-confirmed 2026-07-11). Even when the compose form is loaded and vision-verified, programmatic paste via React setter / contentEditable frequently fails silently on Twitter, HN, Reddit, and LinkedIn. After staging, vision-verify ONE screenshot per platform with the question "What text is actually in the compose field? Empty or has content?" If empty, the form loaded but paste didn't stick — surface this to the user as "compose form ready, paste manually from the .md file." Do NOT claim the draft is staged-and-pasted when the field is empty.
web_extract cannot fetch LinkedIn post bodies (re-confirmed 2026-07-11). The ddgs backend returned ddgs is a search-only backend and cannot extract URL content. Workaround: curl -A "Mozilla/5.0 ... Chrome/126.0.0.0 ..." <linkedin-url> -o /tmp/post.html, then python3 -c "import re; m = re.search(r'<meta[^>]+property=\"og:description\"[^>]+content=\"([^\"]+)\"', open('/tmp/post.html').read()); print(m.group(1) if m else 'NONE')". LinkedIn embeds the full post body in og:description.
Aside MCP repl tool: SKIP notifications/initialized (verified 2026-07-11). The MCP initialize handshake works, but if you send notifications/initialized after the initialize, subsequent tools/call requests return Bad Request: No valid session ID provided even though the session-id header is correctly attached. The working pattern: init → read mcp-session-id from response header → call tools/call immediately, skip notifications/initialized. Also: use top-level await directly in REPL code (the REPL is in module mode) — DO NOT wrap in (async () => { ... })(); IIFEs because the IIFE swallows console.log output via the SSE stream. Top-level console.log('HELLO') works synchronously; await fetch('https://api.ipify.org') then console.log(await r.text()) works async.
browserclaw CLI broken if its editable worktree is deleted (verified 2026-07-11). Symptom: browserclaw --help returns empty; running any browserclaw cookies ... command returns ModuleNotFoundError: No module named 'browserclaw.cli'. Diagnosis: pip show browserclaw shows Editable project location: $HOME/.worktrees/browserclaw-cookies; if that path no longer exists, the editable install in .local/orch-venv/lib/python3.13/site-packages/_editable_impl_browserclaw.pth points to a nonexistent directory and the module fails to import. Fix options: (a) pip install -e /path/to/browserclaw/repo --force-reinstall --no-deps to repoint the .pth, (b) pip uninstall browserclaw && pip install browserclaw to drop the editable install, (c) recreate the worktree at the original path. The Playwright + cookie inject pattern still works without browserclaw — see headless_stage_paste.py for a self-contained alternative.
require('fs') is NOT available in the Aside REPL (verified 2026-07-15). Trying require('fs').writeFileSync(...) inside aside repl returns Error: External modules are not available in the REPL. The screenshot Buffer from p.screenshot() cannot be saved directly from inside the REPL. The verified pattern — capture the base64 via console.log then grep+decode in the parent shell:
This works because top-level await is allowed directly in the REPL (no IIFE wrapper needed — see lesson 13). For multi-platform staging loops, wrap in a Python subprocess.run loop that parses each SCREENSHOT_B64: line and decodes to disk.
Mastodon URLs: mastodon.social/compose is a 404; use mastodon.social/publish (verified 2026-07-15). Old docs and recipes reference /compose, but the modern Mastodon (v4.x) instance returns a 404 Not Found for that path. The compose preview lives at /publish. Caveat:/publish shows the compose form to unauthenticated users, but the "Post" button won't work until you sign in. Verify session state with vision ("Login / Create account buttons visible on the right?") before staging. Other instances (e.g. mastodon.social/@user) have different canonical paths; check the instance's help docs.
LinkedIn share-box trigger uses obfuscated class names that defeat programmatic clicks (verified 2026-07-15)..locator('button[aria-label*="Start a post"]') returns 0 matches. Click-by-text (document.querySelectorAll('button').forEach(el => { if (el.textContent.includes('Start a post')) el.click() })) also returns 0 — LinkedIn renders the "Start a post" box as a <div> with role="button" and randomized class names like share-box-feed-entry__closed-share-box. After 3 failed attempts (locator, click-by-text, click-by-placeholder), the recommended path is: tell the user "click 'Start a post' manually, then paste from linkedin.md". Same fallback applies to Threads (sometimes), Facebook (modal requires click on "What's on your mind, [Name]?" first), and Instagram (no web compose at all).
aside repl CLI silently no-ops on programmatic paste — use Aside HTTP MCP instead (verified 2026-07-17). Switching the staging script from aside repl "..." to the HTTP MCP at 127.0.0.1:8013/mcp is the difference between 9/11 platforms stuck at "compose-ready with empty fields" and 3/11 platforms actually having the draft text in the field. The aside repl path looks identical — every await loc.fill(...) returns without error — but the field stays empty because the underlying Chrome DevTools clipboard-write hook is silently disabled in that mode. Use scripts/stage_in_aside_mcp.py as the canonical staging entry point; treat aside repl paste as a known-broken path.
Bundle open + paste + verify + screenshot in ONE MCP call per platform, never split (verified 2026-07-17). Each openTab(url) opens a fresh tab. If the JS code is split across multiple MCP calls — call 1 opens the tab, call 2 types, call 3 verifies — the typed text is lost because call 2's openTab reopens a new tab on the same URL, which resets the compose form. The fix is one MCP tools/call per platform wrapping (async () => { openTab → fill → verify → screenshot })() in a single IIFE; the screenshot base64 emits on a separate SHOT_<var>: line so the companion RESULT_<var>=<json> line stays small enough to parse reliably.
MCP server at 127.0.0.1:8013/mcp degrades after ~6-8 bundled calls (verified 2026-07-17). Symptom: subsequent tools/call requests return 0 bytes (no SSE error, no console output, the curl process times out after 180s with empty body). Cause: Chrome / Aside daemon contention from too many open tabs / playwright.Page handles held across calls. Recovery: pkill -9 -f aside then open -a "Aside" and wait 10s; aside account use u0; openTab <warmup-url> once to confirm the window has focus; re-run. Or, if the same script that worked minutes ago now returns empty, restart Between MCP sessions — every fresh session starts healthy.
Reddit's old.reddit.com form is fragile — fill sometimes hangs Chrome entirely (verified 2026-07-17). Symptom: locator.fill() for textarea[name='text'] on /r/X/submit?selftext=true triggers an indefinite Chrome hang (no MCP response after 60s+). The same code works for HN (textarea[name='text']) and Mastodon (<textarea>) — the difference is old.reddit's anti-spam heuristics. Workaround: run each Reddit subreddit in its own fresh MCP session, fill title first, then body in a separate call. If the body fill still hangs, surface the draft .md file to the user for manual paste.
Login walls silently reappeared for LinkedIn / Facebook / Threads / Dev.to with Chrome profile u0 = $USER@gmail.com (verified 2026-07-17). Earlier sessions (2026-07-11) reported these platforms as "signed in for the session via fresh openTab"; the cookies appear to have rotated or expired between sessions. Symptom: openTab on the compose URL redirects to the platform's sign-in form (Dev.to shows input#user_email + input#user_password; LinkedIn shows "Welcome back" page). Fix: one-time manual login in the Aside GUI, then re-run staging — u0 cookies refresh for the next 24-72h. Or fall back to headless Playwright + browserclaw cookies inject per references/platform-session-status.md.
Use subprocess.Popen + .communicate(timeout=...), NOT subprocess.run(timeout=...) for MCP curl calls (verified 2026-07-17).subprocess.run(..., timeout=180) silently drops output if the curl process writes its SSE bytes between Python's timeout firing and the process exiting cleanly. Popen + communicate(timeout=180) captures the same data. Indistinguishable on a happy path; visible failure mode is len(out) == 0 after a "successful" call.
Always vision-verify the actual TEXT inside the field after staging (verified 2026-07-17 re-confirmation). The HN stage reported paste: ok=true, len=1131 via the verify step, but the saved screenshot showed only the last 2 sentences of a multi-paragraph body. Playwright's locator.fill() silently truncates on certain React-controlled textareas when the input exceeds ~1000 chars and the field has not been focused first. The fix is await loc.click(); await sleep(300); await loc.fill(text) (already in stage_in_aside_mcp.py), BUT vision-verify is the only reliable cross-check — the verify step reads document.querySelector().value.length which disagrees with what's actually visible after a re-render. Always end Phase 2 with one vision_analyze per platform asking "what text is currently in the field?" before declaring success.
