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.
npx skills add Jamie-BitFlight/claude_skills --skill reuse-before-buildgit clone --depth 1 https://github.com/Jamie-BitFlight/claude_skillsWrote 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/jamie-bitflight/claude_skills/reuse-before-build)<a href="https://agentmods.dev/skills/jamie-bitflight/claude_skills/reuse-before-build"><img src="https://agentmods.dev/badge/skills/jamie-bitflight/claude_skills/reuse-before-build/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/jamie-bitflight/claude_skills/reuse-before-build"><img src="https://agentmods.dev/badge/skills/jamie-bitflight/claude_skills/reuse-before-build.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00060 | $0.00996 |
| Opus 5.5 | $0.00024 | $0.00398 |
| Sonnet 5.5 | $0.00012 | $0.00199 |
| Haiku 4.5 | $0.00006 | $0.00100 |
Grade A, and why
reuse-before-build 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 10d 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.
How it starts
The opening of the file, as written. The whole thing — 83 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Reuse Before Build
Apply this decision gate to a proposed or newly implemented capability, not every changed function. Skip unchanged mechanisms and incidental glue with no independent capability. Select the caller's mode:
- Planning: apply the procedure before choosing an implementation. Carry the decision in the caller's existing task sections, not a new task field or stage.
- Runner: apply during
dh:start-taskexecution, including late discovery. When the dispatch owns an attempt, read Runner handoff before research or closure; it binds lease ordering and durable evidence to that task and attempt. Without an attempt, make the decision but leave attempt-owned persistence and closure to the caller that owns them. - Review: remain read-only. Recover the implementation's requirements and decision from its diff, consumers and task evidence, then assess the choice.
Decision procedure
- Define fit. Name the required behavior and the decisive requirement most capable of disqualifying a candidate. Do not assume a custom implementation.
- Recover or discover nearest first. Inspect prior task context and decisions. Reuse a prior decision only while its requirements, environment, availability and implementation assumptions still hold. Recheck the affected evidence when any of these changes, including a different approach discovered by the worker. If no applicable decision establishes fit, inspect platform/standard-library facilities, repository code and installed dependencies, available CLI/MCP/skills, then maintained ecosystem candidates as justified by the remaining uncertainty.
- Verify decisive fit. Read authoritative candidate documentation. Run a small safe proof of the hardest requirement when its result could change the choice. Mark claims unverified when that check cannot run. Compare integration, compatibility, supported versions/interfaces, licensing, maintenance, supply-chain/security risk and replacement/lifecycle cost only where they could change the decision. A candidate's existence is not proof of fit.
- Decide and stop. Prefer ADOPT (reuse/configure), then ADAPT (minimal integration or upstream extension), then BUILD JUSTIFIED (demonstrated gaps or integration costs materially outweighing reuse). Use UNRESOLVED when the decisive evidence is missing, naming the cheapest check that would settle it. Stop searching when further evidence would not change the choice.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 10d ago First seen · 83 lines · 60 tokens per session scan A a7b0dd686e34
reuse-before-build is a skill published in the GitHub repository Jamie-BitFlight/claude_skills (67 stars, last pushed 4d ago), licensed MIT. It adds 60 tokens to every session and 996 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-10-14.
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