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 alwaysmeticulous/skills --skill meticulous-simulate-and-diffgit clone --depth 1 https://github.com/alwaysmeticulous/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/alwaysmeticulous/skills/meticulous-simulate-and-diff)<a href="https://agentmods.dev/skills/alwaysmeticulous/skills/meticulous-simulate-and-diff"><img src="https://agentmods.dev/badge/skills/alwaysmeticulous/skills/meticulous-simulate-and-diff/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/alwaysmeticulous/skills/meticulous-simulate-and-diff"><img src="https://agentmods.dev/badge/skills/alwaysmeticulous/skills/meticulous-simulate-and-diff.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk warn
- NVIDIA SkillSpector pass
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 | $0.00065 | $0.01630 |
| Opus 5 | $0.00032 | $0.00815 |
| Sonnet 5 | $0.00013 | $0.00326 |
| Haiku 4.5 | $0.00006 | $0.00163 |
Grade A, and why
meticulous-simulate-and-diff 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 — 141 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Simulate a session and analyze diffs
This skill covers running a single simulation and interpreting the results. For the simulate command's full option reference see the meticulous-cli skill's simulate reference.
Before starting, run the
meticulous-cli-updateskill to ensure the Meticulous CLI and skills are up to date — unless it has already run earlier in this conversation, in which case skip it.
Prerequisites
- A
sessionIdto replay - An
appUrl(local dev server, or leave blank to use the original recorded URL) - Optionally: a
baseReplayId— the ID of a prior replay to diff screenshots against. Without this, screenshots are stored but not compared.
If you don't have a baseReplayId, you can find one from a downloaded test run:
meticulous download test-run
# Then inspect ~/.meticulous/test-runs/<testRunId>/coverage.json
# or check the testCases[].replayId fields
Step 1 — Run the simulation
With a base replay (diff mode)
meticulous simulate \
--sessionId=<sessionId> \
--appUrl=<url> \
--baseReplayId=<baseReplayId> \
--headless
Capture the full stdout. Key things to look for:
# Per-screenshot diff outcomes (one line each):
0.412% pixel mismatch for screenshot screenshot-1234.png (threshold is 0.100%) => FAIL!
0.000% pixel mismatch for screenshot screenshot-5678.png (threshold is 0.100%) => PASS
# Final summary block:
=======
View simulation at: https://app.meticulous.ai/projects/<org>/<project>/simulations/<headReplayId>
View comparison with base: https://app.meticulous.ai/projects/<org>/<project>/simulations/<baseReplayId>/compare-to/<headReplayId>
=======
If there are no FAIL! lines: the session is visually identical to the base — report no regressions, then proceed to Step 6.
Proceed to Steps 2–6 to locate and analyse any diffs, then submit feedback.
Without a base replay (quick-check mode)
If no baseReplayId is available, omit it. Screenshots are still stored locally for direct visual inspection:
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 · 141 lines · 65 tokens per session scan A 7ddd4df4f62b
meticulous-simulate-and-diff is a skill published in the GitHub repository alwaysmeticulous/skills (10 stars, last pushed 2d ago), licensed ISC. It adds 65 tokens to every session and 1,630 once invoked, about $0.0003 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 2026-08-31.
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