Semantic Compressor

A fail-closed Claude Code skill for reducing skill and agent Markdown without silently changing behavior.

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[!IMPORTANT] v2.1.0 aligns discovery and frontmatter checks with Claude Code 2.1.305 and fixes several v2.0.0 bugs. Backups made by v2.0.0 remain restorable. If you are upgrading from v1, review CHANGELOG.md first.

What’s new in v2.1.0

• Scan covers what Claude Code loads today: custom commands in .claude/commands/, plugin skills, commands, and agents (including plugins kept in .claude/skills//), and only those agent files Claude Code loads as agents.
• Scan skips, with a reason, names Claude Code refuses, agent files it ignores, frontmatter outside the supported YAML subset, and non-UTF-8 files.
• Validation fails a skill or command candidate whose description and when_to_use grow past Claude Code’s 1,536-character listing cap, and warns when a candidate is still over the cap or a SKILL.md has 500 or more lines.
• Fixed: apply no longer puts the marker where Claude Code reads the listing text of a skill or command without a description.
• Fixed: agents are no longer dropped when the project path contains a folder named like build or dist, and Claude Code worktrees in .claude/worktrees/ no longer list every entrypoint twice.
• Fixed: restore accepts backups written by any v2 release, so upgrading does not strand v2.0.0 backups.

What v2 changes

Semantic Compressor now separates drafting from mutation:

• scan, compress, verify, benchmark, and restore preview are read-only for source files.
• Only explicit apply and restore ... --apply can replace a source file.
• A dependency-free Python control script validates paths, frontmatter, preservation inventories, ratios, hashes, backups, manifests, and rollback state.
• A fresh read-only reviewer judges conceptual equivalence after deterministic checks pass.
• Semantic review is reported as model judgment with evidence, never as an absolute guarantee.