skill-change-logging

skill-change-logging is a skill for Claude Code from vchelaru/FlatRedBall2. It costs 52 tokens per session (920 once invoked), scanned A, original, MIT.

A change-log rule for recording every modification to a FlatRedBall2 skill in a JSONL file, which stores one JSON record per line.

In plain words
What is it for?
Use it whenever a skill is created, edited, deleted, or significantly reorganized. It records the skill path, change type, timestamps, line counts, and motivation.
Why use it?
It provides an exact history of skill changes, including what changed, how many lines changed, and why.

Skill for Claude Code

Written for Claude Code: installed under .claude/. Also seen: reads .claude/ paths.

Install

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.

agentmods
npx agentmods add skills/vchelaru/flatredball2/skill-change-logging
Any agent
npx skills add vchelaru/FlatRedBall2 --skill skill-change-logging
Clone the repo
git clone --depth 1 https://github.com/vchelaru/FlatRedBall2

Made for: Claude Code.

Wrote 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.

agentmods badge for skill-change-logging

README.md
[![agentmods](https://agentmods.dev/badge/skills/vchelaru/flatredball2/skill-change-logging.svg)](https://agentmods.dev/skills/vchelaru/flatredball2/skill-change-logging)
Your own site
<a href="https://agentmods.dev/skills/vchelaru/flatredball2/skill-change-logging"><img src="https://agentmods.dev/badge/skills/vchelaru/flatredball2/skill-change-logging.svg" alt="Measured on agentmods" height="20"></a>
Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 920 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00052 $0.00920
Opus 5 $0.00026 $0.00460
Sonnet 5 $0.00010 $0.00184
Haiku 4.5 $0.00005 $0.00092

Measured yesterday against content hash f7f2ca669fb4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

skill-change-logging 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.

.claude/skills/skill-change-logging/SKILL.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill Change Logging

Use this skill whenever a skill file changes — both the 3rd-party game-dev skills under frb-skills/ and the 1st-party engine-contributor skills under .claude/skills/. Log the canonical path (e.g. frb-skills/animation/SKILL.md, not the symlinked path).

Required Log File

  • Path: .claude/skill_change_log.jsonl
  • Format: one JSON object per line (JSONL)

When to Log

Always append one entry per changed skill when any of these occur:

  • SKILL.md content edits
  • frontmatter name or description updates
  • new skill creation
  • skill deletion
  • significant skill restructure (for example, moving sections into references)

Do not skip logging because a change is "small". If behavior, routing, or guardrails changed, log it.

Required Fields Per Entry

Each JSON object must include:

  • id: integer UTC epoch milliseconds at write time (append-only friendly)
  • timestamp_utc: ISO-8601 UTC timestamp at millisecond precision (YYYY-MM-DDTHH:mm:ss.fffZ)
  • skill: skill name (folder name or frontmatter name)
  • skill_file: repo-relative path
  • change_type: create, update, delete, or restructure
  • lines_added: integer from git diff --numstat
  • lines_removed: integer from git diff --numstat
  • line_ranges_added: array of 1-based line ranges in the post-change file (e.g. ["42-57","89-89"])
  • line_ranges_removed: array of 1-based line ranges in the pre-change file (e.g. ["40-52"])
  • motivating_sample_project: sample project path that motivated the change, or "none" if not sample-driven
  • reason: concise but complete need statement

Logging Workflow

  1. Make skill edits.
  2. Run git diff --numstat -- <skill-file-paths>.
  3. Run git diff -U0 -- <skill-file-paths> and capture hunk line ranges.
  4. Set id to current UTC epoch milliseconds.
  5. Append one JSON line per changed skill to .claude/skill_change_log.jsonl.
  6. Keep reasons short, specific, and action-oriented.

ID Rules

  • IDs are global across the file (not per skill).
  • IDs must be unique; they do not need to be contiguous.
  • Use UTC epoch milliseconds to avoid reading the existing log for max-id lookup.
  • If two entries are created in the same millisecond, increment by +1 locally for subsequent entries in that write batch.

Read the full file on GitHub · 80 lines

Changes

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.

  1. yesterday First seen · 80 lines · 52 tokens per session scan A f7f2ca669fb4

Subscribe to this mod's changes

skill-change-logging is a skill published in the GitHub repository vchelaru/FlatRedBall2 (14 stars, last pushed yesterday), licensed MIT. It adds 52 tokens to every session and 920 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 2026-09-04.

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