Framework Migration Assistant
ArabelaTso/Skills-4-SE
Automatically migrate Python web applications between frameworks (Flask → FastAPI, Django → FastAPI).
House rules for Python dataclasses in PostHog: when to reach for one instead of a tuple or dict[str, Any], which decorator to use (@frozen from posthog.dataclasses), how to name, construct, consume…
Install Writing Dataclasses
$ npx skills add PostHog/posthog --skill writing-dataclasses -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install PostHog/posthog writing-dataclasses --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/PostHog/posthog.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/writing-dataclasses .claude/skills/writing-dataclasses && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "writing-dataclasses" agent skill from https://github.com/PostHog/posthog/tree/master/.agents/skills/writing-dataclasses into .claude/skills/writing-dataclasses/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "writing-dataclasses", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/PostHog/posthog/tree/master/.agents/skills/writing-dataclassesType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add PostHog/posthog --skill writing-dataclasses -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install PostHog/posthog writing-dataclasses --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/PostHog/posthog.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.agents/skills/writing-dataclasses .agents/skills/writing-dataclasses && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "writing-dataclasses" agent skill from https://github.com/PostHog/posthog/tree/master/.agents/skills/writing-dataclasses into .agents/skills/writing-dataclasses/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "writing-dataclasses", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add PostHog/posthog --skill writing-dataclasses -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install PostHog/posthog writing-dataclasses --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/PostHog/posthog.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.agents/skills/writing-dataclasses .cursor/skills/writing-dataclasses && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "writing-dataclasses" agent skill from https://github.com/PostHog/posthog/tree/master/.agents/skills/writing-dataclasses into .cursor/skills/writing-dataclasses/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "writing-dataclasses", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/PostHog/posthog.git --path .agents/skills/writing-dataclasses--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add PostHog/posthog --skill writing-dataclasses -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install PostHog/posthog writing-dataclasses --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/PostHog/posthog.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.agents/skills/writing-dataclasses .gemini/skills/writing-dataclasses && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "writing-dataclasses" agent skill from https://github.com/PostHog/posthog/tree/master/.agents/skills/writing-dataclasses into .gemini/skills/writing-dataclasses/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "writing-dataclasses", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install PostHog/posthog writing-dataclassesInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add PostHog/posthog --skill writing-dataclasses -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/PostHog/posthog.git skills-src && mkdir -p .github/skills && cp -r skills-src/.agents/skills/writing-dataclasses .github/skills/writing-dataclasses && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "writing-dataclasses" agent skill from https://github.com/PostHog/posthog/tree/master/.agents/skills/writing-dataclasses into .github/skills/writing-dataclasses/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "writing-dataclasses", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add PostHog/posthog --skill writing-dataclasses -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install PostHog/posthog writing-dataclasses --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/PostHog/posthog.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.agents/skills/writing-dataclasses .opencode/skills/writing-dataclasses && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "writing-dataclasses" agent skill from https://github.com/PostHog/posthog/tree/master/.agents/skills/writing-dataclasses into .opencode/skills/writing-dataclasses/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "writing-dataclasses", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
writing-dataclasses- GitHub stars
- 40k
- Token cost
- ~1.8k tokens
- SKILL.md length
- 825 words
- Files
- 1
- Skills in repo
- 252
- Repo updated
- First seen
- Licence
- Custom licence
At a glance
House rules for Python dataclasses in PostHog: when to reach for one instead of a tuple or dict[str, Any], which decorator to use (@frozen from posthog.dataclasses), how to name, construct, consume…
- Works in 3 steps: Invariants win over mirroring. Never… → Wire signatures keep their shape.… → Facade contracts that are also request…
- Changing a dataclass
- SKILL.md covers When a dataclass, when not, Which decorator, Naming and Constructing and enforcing…, plus 4 more sections
- Calls python
What it does
Writing Dataclasses is an agent skill from PostHog/posthog, published by the product's own GitHub organization. House rules for Python dataclasses in PostHog: when to reach for one instead of a tuple or dict[str, Any], which decorator to use (@frozen from posthog.dataclasses), how to name, construct, consume and evolve them, how to keep secrets out of repr, and when a function should accept a dataclass instead of its unpacked fields. Use when adding or changing a dataclass, returning or passing several values from a function, converting a tuple or dict payload, deciding frozen=/slots=/kwonly=, or passing a facade contract…
Its SKILL.md is about 1.8k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.
It sits in Backend & APIs, covering Backend development. It works with PostHog, Python, Django and Pydantic. The repository describes itself as: :hedgehog: PostHog is the leading platform for building self-driving products. Our developer tools – AI observability, analytics, session replay, flags, experiments, error…
When your agent uses it
- Changing a dataclass
- Passing several values from a function
- Converting a tuple
- Deciding frozen=/slots=/kwonly=
Example prompts
- “/writing-dataclasses”
Requirements
- Python 3
Workflow steps
3 steps, taken from the first numbered list in SKILL.md.
- Invariants win over mirroring. Never pass a wider type into a callee that needs a narrower one. If the dataclass has url: str | None and…
- Wire signatures keep their shape. Temporal @activity.defn/@workflow.run and celery task boundaries take what they take; the helper behind…
- Facade contracts that are also request bodies are wire signatures too. A contract in facade/contracts.py backed by DataclassSerializer and…
What it can do on your machine
Read from SKILL.md and the folder at commit 10f9ad7. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
python
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Context cost
Writing Dataclasses loads about 1.8k tokens when it runs. Until then it costs about 167 tokens; SKILL.md has 825 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
Its licence (Custom licence) doesn't allow us to republish the file, so here is its outline and opening line. It has 825 words (~1,754 tokens).
“The point of every rule here is the same: values that share a type get swapped silently, and a positional tuple or a dict[str, Any] lets that happen. A named, frozen dataclass makes the swap a typecheck failure instead of…”
- name
- writing-dataclasses
Files
Just SKILL.md in .agents/skills/writing-dataclasses of PostHog/posthog.
Open the folder on GitHubat commit 10f9ad7
Used in 1 other repository
We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders. This page covers the copy in PostHog/posthog, which our catalogue first saw on October 7, 2026.
Compare with similar skills
Writing Dataclasses next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Writing Dataclasses this skillPostHog/posthog | 40k | — | ~1.8k | Automated safety check: Pass | Custom licence | |
| Framework Migration AssistantArabelaTso/Skills-4-SE | 253 | — | ~1.9k | Automated safety check: Pass | Apache-2.0 | |
| Djangoericrisco/rsc-harness | 167 | — | ~3.1k | Automated safety check: Pass | MIT | |
| Fastapiericrisco/rsc-harness | 167 | — | ~5k | Automated safety check: Notes | MIT | |
| Pytestmathiasertl/django-ca | 158 | — | ~924 | Automated safety check: Pass | GPL-3.0 | |
| Fastcrudbenavlabs/fastcrud | 1.6k | — | ~5k | Automated safety check: Pass | MIT |
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Related
Categories
Questions about Writing Dataclasses
What does Writing Dataclasses do?
House rules for Python dataclasses in PostHog: when to reach for one instead of a tuple or dict[str, Any], which decorator to use (@frozen from posthog.dataclasses), how to name, construct, consume…. Writing Dataclasses is an agent skill from PostHog/posthog, published by the product's own GitHub organization.dataclasses), how to name, construct, consume and evolve them, how to keep secrets out of repr, and when a function should accept a dataclass instead of its unpacked fields.
When should I use Writing Dataclasses?
Writing Dataclasses fits situations like: changing a dataclass; passing several values from a function; converting a tuple; deciding frozen=/slots=/kwonly=.
How do I install Writing Dataclasses in Claude Code?
Run `npx skills add PostHog/posthog --skill writing-dataclasses -a claude-code`. Or copy the skill folder (.agents/skills/writing-dataclasses in PostHog/posthog) into .claude/skills/writing-dataclasses in your project. Claude Code loads it when a task matches its description.
How do I install Writing Dataclasses in Codex?
Run `npx skills add PostHog/posthog --skill writing-dataclasses -a codex`. Or copy the skill folder (.agents/skills/writing-dataclasses in PostHog/posthog) into .agents/skills/writing-dataclasses in your project. Codex loads it when a task matches its description.
Can I use Writing Dataclasses in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add PostHog/posthog --skill writing-dataclasses -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/writing-dataclasses, .gemini/skills/writing-dataclasses, .github/skills/writing-dataclasses and .opencode/skills/writing-dataclasses in your project.
What does Writing Dataclasses need to run?
Going by SKILL.md and its folder, Writing Dataclasses needs the command-line tools its instructions call (python). Our summary lists: Python 3.
Does Writing Dataclasses access the network?
SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.
Is Writing Dataclasses safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Writing Dataclasses use?
Writing Dataclasses has a licence file (the repository's licence) that doesn't match a standard licence. Read it on GitHub before reusing the skill.
How many tokens does Writing Dataclasses use?
About 1.8k tokens (SKILL.md is roughly 7k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Writing Dataclasses?
Skills that share tags, products or a category with Writing Dataclasses: Framework Migration Assistant (ArabelaTso/Skills-4-SE, 253 stars), Django (ericrisco/rsc-harness, 167 stars), Fastapi (ericrisco/rsc-harness, 167 stars) and Pytest (mathiasertl/django-ca, 158 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Writing Dataclasses?
PostHog (a GitHub organization, an official publisher) maintains it in PostHog/posthog, which has 40,182 GitHub stars. The repository holds 252 skills in this directory. The repository was last updated on October 8, 2026.
Source: PostHog/posthog on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.