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 SetraTheXX/Codex-Engineering-Workflow-Pack --skill tddgit clone --depth 1 https://github.com/SetraTheXX/Codex-Engineering-Workflow-PackWrote 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/setrathexx/codex-engineering-workflow-pack/tdd)<a href="https://agentmods.dev/skills/setrathexx/codex-engineering-workflow-pack/tdd"><img src="https://agentmods.dev/badge/skills/setrathexx/codex-engineering-workflow-pack/tdd/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/setrathexx/codex-engineering-workflow-pack/tdd"><img src="https://agentmods.dev/badge/skills/setrathexx/codex-engineering-workflow-pack/tdd.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 | $0.00043 | $0.01040 |
| Opus 5.5 | $0.00017 | $0.00416 |
| Sonnet 5.5 | $0.00009 | $0.00208 |
| Haiku 4.5 | $0.00004 | $0.00104 |
Grade A, and why
tdd 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 1mo 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 — 200 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test-Driven Development
Use TDD to implement one observable behavior at a time.
The loop is:
one failing test -> smallest implementation -> refactor -> next test
Do not write all tests first. Do not implement the whole feature before the first failing test proves the path.
Read First
Before editing code, inspect:
docs/agents/test-commands.mddocs/agents/domain.mdCONTEXT.md- relevant ADRs under
docs/adr/ - existing tests near the behavior
- package scripts or equivalent task definitions
If setup docs are missing, infer commands from the repo. Ask only if the verification command or behavior target is unclear.
Workflow
1. Clarify Behavior
Identify public behavior before test shape.
Capture:
- User-visible outcome.
- Acceptance criteria.
- Public interface or entry point.
- Existing behavior that must not regress.
- Out-of-scope behavior.
Ask the user only for product or acceptance decisions that cannot be answered from files or code.
2. Choose The First Vertical Slice
Pick the thinnest end-to-end behavior that proves the feature direction.
A vertical slice should:
- Be independently verifiable.
- Touch real integration points when reasonable.
- Avoid layer-only work with no observable outcome.
- Produce a small but meaningful behavior.
If the requested work is large, list slices and start with the smallest useful one.
3. Select Test Level
Prefer tests through public interfaces.
Good targets:
- Public function or module API.
- HTTP endpoint.
- CLI command.
- UI behavior through user interaction.
- Integration boundary already used by the repo.
Avoid:
- Private methods.
- Internal call counts.
- Mocking the unit that owns the behavior.
- Tests that break when implementation changes but behavior stays the same.
See references/test-quality-guide.md for examples.
4. Red
Write exactly one failing test for one behavior.
Then run the focused test command.
Confirm:
- The test fails.
- The failure is expected.
- The test would pass only if the desired behavior exists.
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.
- 1mo ago First seen · 200 lines · 43 tokens per session scan A 1328b962bf14
tdd is a skill published in the GitHub repository SetraTheXX/Codex-Engineering-Workflow-Pack (1 stars, last pushed 28d ago), licensed MIT. It adds 43 tokens to every session and 1,040 once invoked, about $0.0002 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 2026-08-31.
Other skills, from other repositories
pdlc-feature
An automated workflow for taking a new software feature from a description or requirements document through requirements, design, testing, implementation, review, and release preparation. It keeps one feature ID across the documents and requires tests before implementation.
pdlc-implement
A guarded coding workflow that implements a feature from its design document and existing tests, then checks the result. It requires tests to be written first, following TDD (test-driven development).
pdlc-tdd
A test-first development workflow guided by existing design documents. TDD means writing tests before the code they check; PDLC is a staged product-development process with required preparation steps.
pdlc-loop-run
An automated loop that moves a feature through TDD, implementation, and review. TDD, or test-driven development, means writing tests as part of defining and checking the code’s expected behavior.
test-writing
Writes meaningful tests that actually catch bugs.
tdd
Test-driven development with red-green-refactor loop. Use when user wants to build features or fix bugs using TDD, mentions "red-green-refactor", wants integration tests, or asks for test-first development.