Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/jenreh/harmonyhub-py/writing-python-codenpx skills add jenreh/harmonyhub-py --skill writing-python-codegit clone --depth 1 https://github.com/jenreh/harmonyhub-pyWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00056 | $0.01078 |
| Opus 5 | $0.00028 | $0.00539 |
| Sonnet 5 | $0.00011 | $0.00216 |
| Haiku 4.5 | $0.00006 | $0.00108 |
Grade A, and why
writing-python-code scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
Copies of this mod
2 near-identical copies found in the catalogue:
- python-coding — 95% identical, 9 lines differ
- writing-python-code — 91% identical, 22 lines differ
How it starts
The opening of the file, as written. The whole thing — 122 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Writing Python Code
Quick reference
- Python 3.14 only; deps via uv; line length 88 chars (Ruff/Black).
- No f-strings in logger calls — use
log.info("x: %s", val). - Type annotations on every function and method.
- Files ≤ 1000 lines — refactor via Extract Class, Mixins, Strategy, etc.
- Coverage ≥ 80% for non-Reflex classes and Reflex State classes.
- Task runner:
task format,task lint,task test(notmake).
Code style
Logging
import logging
log = logging.getLogger(__name__)
log.info("Loaded items: %d", count) # ✅ parameterized
# log.info(f"Loaded items: {count}") # ❌ f-string
Never use print or printf. Log levels: debug → internal state (default), info → milestones, warning → recoverable, error → serious.
Type hints
def process(data: dict[str, Any], count: int = 0) -> list[str]: ...
async def handler(value: str) -> AsyncGenerator[Any, Any]:
yield
- Do not mix
Literal[...]withstr— pick one. - Remove unused imports immediately (F401).
- Remove unused args or prefix with
_(ARG001).
Imports & formatting
- Ruff handles lint + format; run
task formatbefore committing. - Break long calls/strings to fit 88 chars.
Ruff rules to watch (project-specific)
| Code | Rule | Fix |
|---|---|---|
| UP031 | No %-formatting outside logger calls — use f-strings |
Replace "x %s" % val with f"x {val}" |
| I001 | Import order | Auto-fixed by task format |
| PLC0415 | No local imports inside functions or test methods | Move to top of file |
| B017 | pytest.raises(Exception) too broad |
Use specific exception, e.g. pytest.raises(ValidationError) |
File size rule
No Python file may exceed 1000 lines. When approaching the limit, apply clean code refactoring strategies.
Design patterns & refactoring strategies: See references/clean-code.md.
Testing
Coverage target: ≥ 80% for services, repositories, models, utilities, and Reflex State classes. UI component rendering is best-effort.
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 122 lines · 56 tokens per session scan A 3bf14d8185fb
writing-python-code is a skill published in the GitHub repository jenreh/harmonyhub-py (5 stars, last pushed 12d ago), licensed MIT. It adds 56 tokens to every session and 1,078 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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