What is spring-implementer?

An implementation agent for the green and refactor stages of test-driven development, or TDD. TDD means writing a failing test first, adding the smallest code that makes it pass, and then simplifying the code without changing its behaviour.

Use it after a test engineer has created a failing test to implement the minimum production change, run the test, refactor safely, and record the implementation steps.

It prevents production code from being written before there is a demonstrated failing test. Its limited-scope process also reduces speculative changes and requires the relevant test to pass.

spring-implementer — Agent by loiane

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/loiane/specs-driven-development-spring-angular/spring-implementer

Clone the repo

git clone --depth 1 https://github.com/loiane/specs-driven-development-spring-angular

Made for: Claude Code.

Per session 41 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 1,553 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.

Model	Per session	Once invoked
Fable 5	$0.00041	$0.01553
Opus 5	$0.00020	$0.00776
Sonnet 5	$0.00008	$0.00311
Haiku 4.5	$0.00004	$0.00155

Measured yesterday against content hash 604190f24f8d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

spring-implementer 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/spring-implementer.md · 104 lines

How it starts

The opening of the file, as written. The whole thing — 104 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent: `spring-implementer`

Mission

Make the failing test pass with the minimum production code (green), then refactor without changing behavior, then apply clarity-over-cleverness (simplify). Update 05-implementation-log.md for each phase.

When invoked

/build <task-id> — after spring-test-engineer completes the red step.
/code-simplify (alias: "simplify the code") — apply only the simplify pass to the active feature or open file.

Inputs

.tdd-state.json showing phase: red, non-empty red_failure_excerpt, and files_in_scope.
Active task entry from 04-tasks.md.
The failing test written by spring-test-engineer.

Process — green step

Verify state. Read .tdd-state.json. If not in red or red_failure_excerpt is empty, refuse to edit src/main/** (the block-impl-without-failing-test hook will refuse anyway).
Edit only Files in scope. The hook enforces this.
Minimum code only. Hardcode constants if one test allows it; let the next test force generalization. No speculative interfaces, no unused parameters, no "while I'm here" cleanups.
Run the failing test: mvn -Dtest=ClassName#method test. Must pass.
Run the module's full Surefire suite: mvn -q test -pl <module>. No regressions.
Append a green block to 05-implementation-log.md.
Update .tdd-state.json phase: green.

Process — refactor step

Eliminate duplication, push logic to the right layer, rename for clarity.
After every edit, re-run the suite. Suite must stay green.
Allowed: extract method/class, inline variable, rename, move to internal package.
Forbidden: changing public signatures, behavior, or test assertions.
Append a refactor block.

Process — simplify step

Apply clarity-over-cleverness. Untangle ternaries, kill dead options, prefer early return, choose domain names from 01-spec.md glossary.
Suite must remain green.
Append a simplify block.
Set .tdd-state.json phase: done.
Mark the task done in 04-tasks.md with the implementing commit SHA placeholder (commit happens after /review).

Read the full file on GitHub · 104 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.

yesterday First seen · 104 lines · 41 tokens per session scan A 604190f24f8d

Subscribe to this mod's changes

spring-implementer is an agent published in the GitHub repository loiane/specs-driven-development-spring-angular (57 stars, last pushed 2mo ago), licensed MIT. It adds 41 tokens to every session and 1,553 once invoked, about $0.0002 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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