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 AbdurRafay2004/handoff --skill tddgit clone --depth 1 https://github.com/AbdurRafay2004/handoffWrote 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/abdurrafay2004/handoff/tdd)<a href="https://agentmods.dev/skills/abdurrafay2004/handoff/tdd"><img src="https://agentmods.dev/badge/skills/abdurrafay2004/handoff/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/abdurrafay2004/handoff/tdd"><img src="https://agentmods.dev/badge/skills/abdurrafay2004/handoff/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 | $0.00041 | $0.01392 |
| Opus 5.5 | $0.00016 | $0.00557 |
| Sonnet 5.5 | $0.00008 | $0.00278 |
| Haiku 4.5 | $0.00004 | $0.00139 |
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 — 154 lines — stays where its author put it; the contents beside it link to each section on GitHub.
TDD
Part of the Build phase — see the workflow skill for tiers and sequencing.
Tier rule: mandatory for T3 (money, auth, user data, migrations); recommended for T2 on the affected path; skipped for T1 (copy/styling). Within its tier, the discipline is absolute: no production code without a failing test first. Bug fixes always get a failing test reproducing the bug, at any tier — a fix without a test doesn't stick.
Philosophy
Tests verify behavior through public interfaces, not implementation details. Code can change entirely; tests shouldn't.
Good tests are integration-style: they exercise real code paths through public APIs and read like a specification — "user can checkout with valid cart" tells you exactly what capability exists. They survive refactors because they don't care about internal structure.
Bad tests are coupled to implementation: they mock internal collaborators, test private methods, or verify through side channels (querying the database directly instead of using the interface). The warning sign: the test breaks when you refactor but behavior hasn't changed.
Core proof: if you didn't watch the test fail, you don't know it tests the right thing. A test written after the code passes immediately — and passing immediately proves nothing.
Anti-pattern: horizontal slices
Do not write all tests first, then all implementation. Bulk-written tests test imagined behavior — the shape of data structures rather than user-facing behavior — and become insensitive to real changes.
WRONG (horizontal): RED: test1..test5 → GREEN: impl1..impl5
RIGHT (vertical): test1→impl1, test2→impl2, test3→impl3 ...
Vertical slices via tracer bullets: one test → one implementation → repeat. Each test responds to what the previous cycle taught you.
Workflow
1. Plan the behaviors
Read the nearest CONTEXT.md / .handoff/context/ so test names match the
project's domain language. Then, before any code:
What ships with it
1 file 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 · 154 lines · 41 tokens per session scan A 94a25c26b5ab
tdd is a skill published in the GitHub repository AbdurRafay2004/handoff (4 stars, last pushed 12d ago), licensed MIT. It adds 41 tokens to every session and 1,392 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
building
Use when writing production code test-first: the RED-GREEN-REFACTOR cycle, false-RED detection, vertical slicing, scope escalation, test process discipline, and code generation patterns.
plan
A planning skill that turns a spec.md specification into a milestone-based implementation plan using test-driven development (TDD), where tests are written to guide the code.
execute
A milestone-based coding workflow that uses test-driven development (TDD): write a test, implement the change, and verify it for each milestone listed in milestones.json.
bad-case-to-dpo
A guide to turning failed production agent runs into training and evaluation data. It explains how to find the first mistake, create preference examples for DPO (Direct Preference Optimization), and check that a fix does not damage other tasks.
auto-loop
TDD-based autonomous development loop with checkpoint recovery and observability changelog.
workflow
Run the complete 5-step development workflow: focus problem → prevent over-development → test-first (TDD) → document → smart commit. Use when starting a new feature, or when the user runs /workflow or asks for the full development flow.