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 skills add oborchers/fractional-cto --skill project-structuregit clone --depth 1 https://github.com/oborchers/fractional-ctoWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/oborchers/fractional-cto/project-structure)<a href="https://agentmods.dev/skills/oborchers/fractional-cto/project-structure"><img src="https://agentmods.dev/badge/skills/oborchers/fractional-cto/project-structure/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/oborchers/fractional-cto/project-structure"><img src="https://agentmods.dev/badge/skills/oborchers/fractional-cto/project-structure.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What 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 5.1 | $0.00097 | $0.02589 |
| Opus 5.5 | $0.00039 | $0.01036 |
| Sonnet 5.5 | $0.00019 | $0.00518 |
| Haiku 4.5 | $0.00010 | $0.00259 |
Grade A, and why
project-structure 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 3d 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.
How it starts
The opening of the file, as written. The whole thing — 201 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Use the src/ Layout and a Canonical Directory Structure
A broken project structure causes packaging bugs that only surface after publishing. The most common failure: tests pass locally because Python adds the working directory to sys.path, but the installed package is missing files. The src/ layout eliminates this entire class of bugs by design. Every packaging expert -- Hynek Schlawack, the PyPA, the Pallets team -- has converged on this layout. Projects like pytest, pip, Flask, Black, Hatch, and attrs all use it. No major project has ever migrated away from src/ layout.
src/ Layout vs Flat Layout
Place the importable package inside a src/ directory. This forces an editable install (pip install -e . or uv pip install -e .) before tests can import the package, proving that packaging works as part of normal development.
| Aspect | src/ Layout | Flat Layout |
|---|---|---|
| Test safety | Tests cannot accidentally import from working directory | Tests may pass even when packaging is broken |
| Tool defaults | Default for hatch new, uv init --lib, pdm init |
Default for flit init (historical) |
| Used by | pytest, pip, Flask, Black, Hatch, attrs | FastAPI, Pydantic, httpx (predate consensus) |
| Recommendation | Use for all new packages | Only for existing projects already using it |
Flat layout mitigation (if you must keep it): add --import-mode=importlib to pytest and test against the built wheel in CI.
Canonical Directory Structure
Start every new Python package from this structure:
my-package/ # Repository root (kebab-case)
src/
my_package/ # Importable package (snake_case)
__init__.py # Public API, __all__, version
py.typed # PEP 561 marker (empty file)
core.py # Primary public module
models.py # Data models
exceptions.py # Custom exception hierarchy
_internal/ # Private implementation
__init__.py
_utils.py
_compat.py # Python version shims
cli.py # CLI entry point (see cli-architecture skill)
tests/
conftest.py # Shared fixtures
test_core.py
test_models.py
docs/
index.md
pyproject.toml # Single configuration file
README.md
LICENSE
CHANGELOG.md
.gitignore
.pre-commit-config.yaml
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.
- 3d ago First seen · 201 lines · 97 tokens per session scan A b6636bf32105
project-structure is a skill published in the GitHub repository oborchers/fractional-cto (32 stars, last pushed 3d ago), licensed MIT. It adds 97 tokens to every session and 2,589 once invoked, about $0.0004 per session on Opus 5.5. 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 2026-10-13.
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