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 bostonaholic/team --skill principle-pre-image-firstgit clone --depth 1 https://github.com/bostonaholic/teamWrote 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/bostonaholic/team/principle-pre-image-first)<a href="https://agentmods.dev/skills/bostonaholic/team/principle-pre-image-first"><img src="https://agentmods.dev/badge/skills/bostonaholic/team/principle-pre-image-first/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/bostonaholic/team/principle-pre-image-first"><img src="https://agentmods.dev/badge/skills/bostonaholic/team/principle-pre-image-first.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 | $0.00022 | $0.00173 |
| Opus 5 | $0.00011 | $0.00086 |
| Sonnet 5 | $0.00004 | $0.00035 |
| Haiku 4.5 | $0.00002 | $0.00017 |
Grade A, and why
principle-pre-image-first 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 4d 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.
What it actually says
Pre-image First
Before mutation, capture the untouched baseline and a recovery anchor or pre-image; No pre-image, no destructive write.
- Run checks BEFORE the operation so later failures classify as pre-existing or introduced.
- Capture the recovery anchor before rewrites and report it on success and failure; preserve
git reset --hard <sha>recovery where applicable. - Cache bodies before composing replacements for rewrite, close, or overwrite operations.
- Compare the target with its pre-image at write time; skip and report drift.
- Apply
principle-idempotent-rerunsto this comparison on re-run. - A baseline that could not run is UNKNOWN and never proves preservation.
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.
- 4d ago Changed · -15 lines · -24 tokens per session 4956a1d0c5a1
- 6d ago First seen · 32 lines · 46 tokens per session scan A 0126a89ad009
principle-pre-image-first is a skill published in the GitHub repository bostonaholic/team (11 stars, last pushed today), licensed MIT. It adds 22 tokens to every session and 173 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 2026-09-03.
Other skills, from other repositories
git-integration
Git commit patterns, formats, and conventions for GSD methodology. Provides atomic commits per task, structured commit messages, planning file commits, branch management, and milestone tag operations.
audit-trail
Full traceability from PRD to code commit through the CCPM spec-driven pipeline.
strict-tdd
Strict RED->GREEN->REFACTOR test-driven development with enforcement. Never write production code before a failing test. Atomic commits per TDD cycle.
maintenance-orchestration
Technical debt management including branch cleanup, doc verification, TODO scanning, and dependency auditing.
worktree-isolation
Manage git worktree lifecycle for safe, isolated parallel development.
github-sync
Bidirectional synchronization of epics and tasks with GitHub issues, labels, and relationships.