Compile every agent's plugin from one canonical source #63

Component

Something else: a canonical source for every skill, rule and agent, and the compiler that builds each agent's plugin from it

Experience

• Owner (maintains the plugin): edits each skill, rule and agent once, in one canonical folder. make build writes every agent's plugin from it, Claude Code's included, and a free check in CI fails when a generated file is stale or a target leaves something out.
• Operator (works in Claude Code): notices nothing. The Claude Code plugin the build writes is byte for byte the one installed today.

Proposed behaviour

• A canonical folder holds the Markdown of the eight skills, five rules and three agents, with neutral markers wherever agents differ. The spike in Spike: run the plugin in Codex, Cursor and Kiro as well as Claude Code #61 measured where they differ:
  • skill arguments;
  • ! shell prefetch;
  • ${CLAUDE_SKILL_DIR};
  • the question tool;
  • agent fields;
  • how rules reach a session.
• One target folder per agent holds that agent's generator. This issue builds the compiler and the first target, Claude Code.
• plugins/freethinking/ becomes the Claude Code target's generated output. Its first build must reproduce today's plugins/freethinking/ byte for byte, so the move changes no behaviour.
• The build is stdlib Python behind make build. A stdlib unittest check under checks/ rebuilds into a temporary folder and fails when the checked-in output differs, or when a target is incomplete.

Motivating case

A first design kept plugins/freethinking/ as the source and added plain-word fallbacks beside each Claude Code feature, generating only the gaps. The author pivoted to compiling from canonical, for three reasons:

• The spike showed agents differ in exactly the places markers express.
• One fallback already failed: in the spike, Codex never read a template given only as ${CLAUDE_SKILL_DIR}.
• One folder per agent keeps each agent's format changes in one place.

Done when

• make build regenerates plugins/freethinking/ with no diff.
• The freshness and completeness check runs in make validate.
• claude plugin validate --strict still passes.

Depends on

Nothing; this is the first stream in .freethinking/strategies/multi-tool-plugin.md. Design with /freethinking:hld .freethinking/strategies/multi-tool-plugin.md canonical-source.