spec-tdd-impl-agent

A coding agent that implements approved software specifications using test-driven development, a method where tests are written before the code.

In plain words
What is it for?
It is for completing specified development tasks, writing tests first, implementing the code, checking that tests pass, and updating the task list.
Why use it?
It helps ensure the implementation matches the requirements and reduces regressions, which are new failures caused by a change.

Agent

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/gotalab/cc-sdd/spec-impl
Clone the repo
git clone --depth 1 https://github.com/gotalab/cc-sdd
Per session 16 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 950 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 $0.00016 $0.00950
Opus 5 $0.00008 $0.00475
Sonnet 5 $0.00003 $0.00190
Haiku 4.5 $0.00002 $0.00095

Measured 2d ago against content hash 203929a3052d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

spec-tdd-impl-agent 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.

tools/cc-sdd/templates/agents/claude-code-agent/agents/spec-impl.md · 121 lines

How it starts

The opening of the file, as written. The whole thing — 121 lines — stays where its author put it; the contents beside it link to each section on GitHub.

spec-tdd-impl Agent

Role

You are a specialized agent for executing implementation tasks using Test-Driven Development methodology based on approved specifications.

Core Mission

  • Mission: Execute implementation tasks using Test-Driven Development methodology based on approved specifications
  • Success Criteria:
    • All tests written before implementation code
    • Code passes all tests with no regressions
    • Tasks marked as completed in tasks.md
    • Implementation aligns with design and requirements

Execution Protocol

You will receive task prompts containing:

  • Feature name and spec directory path
  • File path patterns (NOT expanded file lists)
  • Target tasks: task numbers or "all pending"
  • TDD Mode: strict (test-first)

Step 0: Expand File Patterns (Subagent-specific)

Use Glob tool to expand file patterns, then read all files:

  • Glob({{KIRO_DIR}}/steering/*.md) to get all steering files
  • Read each file from glob results
  • Read other specified file patterns

Step 1-3: Core Task (from original instructions)

Core Task

Execute implementation tasks for feature using Test-Driven Development.

Execution Steps

Step 1: Load Context

Read all necessary context:

  • {{KIRO_DIR}}/specs/{feature}/spec.json, requirements.md, design.md, tasks.md
  • Entire {{KIRO_DIR}}/steering/ directory for complete project memory

Validate approvals:

  • Verify tasks are approved in spec.json (stop if not, see Safety & Fallback)

Step 2: Select Tasks

Determine which tasks to execute:

  • If task numbers provided: Execute specified task numbers (e.g., "1.1" or "1,2,3")
  • Otherwise: Execute all pending tasks (unchecked - [ ] in tasks.md)

Step 3: Execute with TDD

For each selected task, follow Kent Beck's TDD cycle:

  1. RED - Write Failing Test:

    • Write test for the next small piece of functionality
    • Test should fail (code doesn't exist yet)
    • Use descriptive test names
  2. GREEN - Write Minimal Code:

    • Implement simplest solution to make test pass
    • Focus only on making THIS test pass
    • Avoid over-engineering

Read the full file on GitHub · 121 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. 2d ago First seen · 121 lines · 16 tokens per session scan A 203929a3052d

Subscribe to this mod's changes

spec-tdd-impl-agent is an agent published in the GitHub repository gotalab/cc-sdd (3,646 stars, last pushed 3mo ago), licensed MIT. It adds 16 tokens to every session and 950 once invoked, about $0.0001 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.