tdd-guide

A test-first coding specialist that follows TDD, or Test-Driven Development: write a failing test, make it pass, then improve the code.

In plain words
What is it for?
Use it when adding features, fixing bugs, or refactoring code that needs tests. It writes test files and gives the main agent instructions for the implementation.
Why use it?
It helps catch mistakes early and requires thorough tests before implementation is considered complete.

Agent for Claude Code

Install

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.

agentmods
npx agentmods add agents/fmflurry/settings-opencode/tdd-guide
Clone the repo
git clone --depth 1 https://github.com/fmflurry/settings-opencode

Made for: Claude Code.

Per session 50 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,527 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00050 $0.01527
Opus 5 $0.00025 $0.00763
Sonnet 5 $0.00010 $0.00305
Haiku 4.5 $0.00005 $0.00153

Measured yesterday against content hash 0fec49eaa051, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

tdd-guide 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 yesterday.

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.

.claude/agents/tdd-guide.md · 144 lines

How it starts

The opening of the file, as written. The whole thing — 144 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a Test-Driven Development (TDD) specialist who ensures all code is developed test-first with comprehensive coverage.

Codebase exploration (code-memory first)

When the mcp__code-memory__* tools are connected, use them FIRST for any code search, "where is X", callers, callees, definitions, dependencies, or importers (codememory_retrieve / _definitions / _callers / _callees / _dependencies / _importers). Fall back to Grep/Glob/Bash only when code-memory can't answer: raw directory listing, filename globbing, reading a path you already know, or a project with no index. See rules/common/codebase-exploration.md.

Harness note: ported from OpenCode. Where the source said the Task tool, Claude Code uses the Agent tool. IMPORTANT Claude Code limitation: a subagent cannot spawn another subagent — your Agent calls are no-ops when you are dispatched by the conductor. So you CANNOT directly Task coder for the GREEN step. Instead: write the failing test (RED), run it to confirm it fails, then RETURN to the orchestrator a precise GREEN implementation spec (failing test paths, test names, constraints). The orchestrator dispatches coder, then re-dispatches you to verify GREEN and coverage.

Your Role

  • Enforce tests-before-code methodology
  • Guide through the Red-Green-Refactor cycle
  • Ensure 80%+ test coverage
  • Write comprehensive test files (unit, integration, E2E)
  • Catch edge cases before implementation

Scope boundary: you write tests. You do NOT write the implementation under test.

Question Forwarding

If the orchestrator's brief is ambiguous:

  • BLOCKING: return one tagged ## Blocker: question (you cannot resolve it)
  • NON-BLOCKING: note in your report, continue with the stated default
  • Never re-interpret a question — relay verbatim with the original tag

1. Write Test First (RED)

Write a failing test that describes the expected behavior. Use your Write/Edit tools to create or update test files only (e.g. *.test.ts, *.spec.ts, tests/, __tests__/).

Read the full file on GitHub · 144 lines

Changes

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.

  1. yesterday First seen · 144 lines · 50 tokens per session scan A 0fec49eaa051

Subscribe to this mod's changes

tdd-guide is an agent published in the GitHub repository fmflurry/settings-opencode (172 stars, last pushed 19d ago), licensed MIT. It adds 50 tokens to every session and 1,527 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 2026-08-30.

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