Emit a plugin for multiple agents

How to emit a plugin for multiple agents

A plugin can target Claude Code, Codex, or both. The SKILL.md files are portable and shared; only the native manifests differ per agent. They are generated from the canonical library.json, never hand-edited.

1. Declare the targets

In library.json:

{ "agent-targets": ["claude", "codex"] }

2. Generate the native manifests

node scripts/generators/gen-manifest.mjs . --write --target=all

• --target=all writes manifest.generated.json, .claude-plugin/plugin.json, and .codex-plugin/plugin.json.
• --target=claude or --target=codex writes just one.

.claude-plugin/plugin.json carries the shared spine (name, version, description, author, homepage, repository, keywords). .codex-plugin/plugin.json adds a "skills": "./skills/" pointer and an interface marketplace block (displayName, category) for the Codex plugin system.

3. Validate

• node scripts/check.mjs runs S6 (per-target-presence): each declared target must have its native manifest on disk.
• U8 warns if a generated manifest’s name/version drifts from library.json - regenerate to fix.

4. (Local) round-trip against Codex

With the codex CLI installed, tests/integration/codex-roundtrip.test.mjs wraps the emitted .codex-plugin/plugin.json in a throwaway local marketplace, installs it, and confirms the skill is ingested (not merely listed). It runs with npm test locally and skips when codex is absent (for example in CI).

Marketplace catalog generation (publishing many plugins) is a separate, later step.