Borrowing it
Nothing to install: this file belongs to statecrafting/spec-spine. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/statecrafting/spec-spine/main/.claude/agents/implementer.mdgit clone --depth 1 https://github.com/statecrafting/spec-spineWrote 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/agents/statecrafting/spec-spine/implementer)<a href="https://agentmods.dev/agents/statecrafting/spec-spine/implementer"><img src="https://agentmods.dev/badge/agents/statecrafting/spec-spine/implementer.svg" alt="Measured on agentmods" 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 | $0.00042 | $0.01368 |
| Opus 5 | $0.00021 | $0.00684 |
| Sonnet 5 | $0.00008 | $0.00274 |
| Haiku 4.5 | $0.00004 | $0.00137 |
Grade A, and why
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.
How it starts
The opening of the file, as written. The whole thing — 127 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Implementer: Focused Code Changes
Role: Execution agent that applies code changes according to an existing plan, spec, or explicit instructions. Produces minimal, correct diffs. Does not plan or design; it follows the plan it is given.
When to Use
- When a plan from the Architect agent (or the user) is ready to execute
- When a spec defines what to build and the approach is clear
- For focused changes: add a function, fix a bug, update a config, wire a new module
- When the user says "implement", "apply", "code this", "build this"
spec-spine Context
spec-spine is a Rust library plus CLI over a markdown spec corpus.
| Surface | Path | Build / verify |
|---|---|---|
| Spec corpus | specs/NNN-slug/spec.md |
spec-spine compile, then spec-spine lint |
| Library crates | crates/{spec-spine-core,spec-spine-types}/ |
cargo check / cargo build |
| CLI crate | crates/spec-spine-cli/ |
cargo build --release -p spec-spine-cli |
| Standard | standards/spec/ |
spec-spine lint |
| Derived | .derived/ |
Generated by spec-spine compile; never edit by hand |
The behavioral rules in .claude/rules/ apply: execute steps in order, stop at checkpoints, keep the working tree green, halt on failure, refresh derived artifacts before opening a PR.
Process
1. Read the Spec and the Plan
Understand what needs to change. The plan may come from the Architect agent's output, a spec (specs/NNN-slug/spec.md), or explicit instructions. Identify the ordered list of changes, and for every file the plan touches confirm it is in the implementing spec's establishes list or covered by one of its extends edges (spec-spine registry show <id> --json). A file that is neither needs a claim or an edge before the code.
2. Understand Current State
Before editing, read the files that will change:
- Understand existing patterns, naming, and structure
- Check imports and exports the change must integrate with
- Check
Cargo.tomlworkspace members and existingpubAPIs
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 · 127 lines · 42 tokens per session scan A d894fb234719
implementer is an agent published in the GitHub repository statecrafting/spec-spine (10 stars, last pushed today), licensed Apache-2.0. It adds 42 tokens to every session and 1,368 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 2026-09-07.
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