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 chrono-meta/forge-harness --skill prompt-regressiongit clone --depth 1 https://github.com/chrono-meta/forge-harnessWrote 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/chrono-meta/forge-harness/prompt-regression)<a href="https://agentmods.dev/skills/chrono-meta/forge-harness/prompt-regression"><img src="https://agentmods.dev/badge/skills/chrono-meta/forge-harness/prompt-regression/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/chrono-meta/forge-harness/prompt-regression"><img src="https://agentmods.dev/badge/skills/chrono-meta/forge-harness/prompt-regression.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 2 findings, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Excessive Agency · line 6 Skill selects an external model or provider that may use a different account or billing plan than the operator expects. Undisclosed model switches can cause unexpected cost or quota consumption.Fix: Remove the model/provider override or disclose it prominently and require explicit operator approval before invoking an external coding CLI or billed model.
- medium Agent Snooping · line 152 Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
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 | $0.00106 | $0.02547 |
| Opus 5 | $0.00053 | $0.01273 |
| Sonnet 5 | $0.00021 | $0.00509 |
| Haiku 4.5 | $0.00011 | $0.00255 |
Grade A, and why
prompt-regression 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 9d 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 — 225 lines — stays where its author put it; the contents beside it link to each section on GitHub.
prompt-regression — Harness Regression Detection
After CLAUDE.md edits, rule changes, or new skill additions, harness behavior can silently regress. This skill runs a lightweight probe suite against the changed assets and compares outputs against saved baselines to surface regressions before they reach production.
Scope distinction
- harness-doctor: structural completeness (files, links, drift)
- prompt-regression: behavioral correctness — did the change alter expected AI response patterns?
Triggers
/prompt-regression- "prompt regression", "regression check", "regression test"
- "did my rule change break anything", "test harness changes", "verify harness behavior", "make sure my edit didn't change behavior"
- After significant CLAUDE.md edits or new skill commits
Execution Steps
Step 1. Identify Changed Assets
# What changed since last commit (or last N commits)
git diff HEAD~1 --name-only -- CLAUDE.md .claude/ plugins/
Classify each changed file:
CLAUDE.md→ core behavior (high impact).claude/rules/*.md→ rule layer (medium impact)plugins/*/skills/*/SKILL.md→ skill behavior (scoped impact)plugins/*/skills/*/SKILL.md(trigger phrases changed) → trigger routing (high impact)
If no changes detected: report "No harness changes since last commit — regression check skipped."
Step 2. Load Probe Suite
Check for custom probes:
ls .claude/regression/probes.md 2>/dev/null || echo "NO_CUSTOM_PROBES"
If custom probes exist: load and use them. The hub repo ships its golden probe set (known-answer offline eval, 33 probes with check classes — 27 mandatory-pass · 1 measured · 5 judged, of which 2 rows are inert deletion anchors, so live coverage is 31) at exactly this path — when present it is canonical and supersedes the default matrix below.
Count from the file, not from this line:
grep -cE '^\| *[A-Z][A-Z0-9-]*-[0-9]+*\|' .claude/regression/probes.md. Both this number and the tally insideprobes.mdread32until 2026-08-12, when the actual count was 33 — a probe had been added to section A without touching either summary. A count duplicated in two files rots independently; if the two disagree, the file wins and both get corrected.
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.
- 9d ago First seen · 225 lines · 106 tokens per session scan A 1de29bdf11b3
prompt-regression is a skill published in the GitHub repository chrono-meta/forge-harness (14 stars, last pushed today), licensed MIT. It adds 106 tokens to every session and 2,547 once invoked, about $0.0005 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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