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/skills/implement-plan/SKILL.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/skills/statecrafting/spec-spine/implement-plan)<a href="https://agentmods.dev/skills/statecrafting/spec-spine/implement-plan"><img src="https://agentmods.dev/badge/skills/statecrafting/spec-spine/implement-plan.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 | $0.00039 | $0.01134 |
| Opus 5 | $0.00019 | $0.00567 |
| Sonnet 5 | $0.00008 | $0.00227 |
| Haiku 4.5 | $0.00004 | $0.00113 |
Grade A, and why
implement-plan 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 — 120 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Implement Plan
Execute a plan document (the architect agent's output, saved to a file)
while keeping progress visible and the tree green. For implementing one
spec end to end, prefer /build <spec-id>: it is the protocol. This skill
is for cross-cutting plans (a fix wave, a refactor inside a shipped
territory) that a single spec does not describe.
Input
Plan file path: $ARGUMENTS. If absent, look for *.plan.md in the
session scratchpad and under any plans directory the project keeps, list
candidates, and ask.
The plan's own status field (draft, in-development, in-review,
completed, blocked) is a planning vocabulary for the plan file only.
It is not the spec status or implementation field; never write it
into a spec.md.
Phase 0: parse
- Read the plan in full.
- Extract: frontmatter (status, dates), goals, acceptance criteria,
implementation steps, existing checkboxes, and the owning spec of
every path the plan touches (
spec-spine registry show <id> --json,spec-spine index coveragefor the unclaimed ones). - Validate readiness: no clear acceptance criteria or steps means stop
and ask;
completedmeans confirm before redoing;blockedmeans ask what unblocks it. - If any step touches a shipped spec's territory in a way its behavior
section does not describe, stop: that needs a spec amendment first
(
.claude/rules/adversarial-prompt-refusal.md).
Phase 1: task list and checkpoint
Build one checkbox per acceptance criterion and per concrete step. Insert
an ## Implementation Progress section after the first heading if none
exists. Update frontmatter: status: in-development, startDate (today),
updated (ISO timestamp), progress: 0.
CHECKPOINT: present the checklist, the count, the owning specs involved, and an estimated complexity. Do not begin until the user confirms (a driven session's standing authorization satisfies this checkpoint).
Phase 2: implementation
Per task:
- Announce the task.
- Implement it, on a feature branch, never on the default branch.
- Verify: the narrowest test target the stack offers, then the gate as
AGENTS.mdlists it whenever the task touched a spec-owned path, aspec.md, a manifest, or any hashed input (spec-spine.toml [index] extra_hashed_inputs; typically the harness, design docs, workflows, standards). - Update the plan file: check the box, recompute
progress(checked over total, rounded), updateupdated. - Next task.
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 · 120 lines · 39 tokens per session scan A 699a728d171d
implement-plan is a skill published in the GitHub repository statecrafting/spec-spine (10 stars, last pushed today), licensed Apache-2.0. It adds 39 tokens to every session and 1,134 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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