feat: add OpenCode/Codex outputs and update changelog (#104)

* Add OpenCode converter coverage and specs

* Add Codex target support and spec docs

* Generate Codex command skills and refresh spec docs

* Add global Codex install path

* fix: harden plugin path loading and codex descriptions

* feat: ensure codex agents block on convert/install

* docs: clarify target branch usage for review

* chore: prep npm package metadata and release notes

* docs: mention opencode and codex in changelog

* docs: update CLI usage and remove stale todos

* feat: install from GitHub with global outputs

AGENTS.md

@@ -0,0 +1,48 @@
+# Agent Instructions
+
+This repository contains a Bun/TypeScript CLI that converts Claude Code plugins into other agent platform formats.
+
+## Working Agreement
+
+- **Branching:** Create a feature branch for any non-trivial change. If already on the correct branch for the task, keep using it; do not create additional branches or worktrees unless explicitly requested.
+- **Safety:** Do not delete or overwrite user data. Avoid destructive commands.
+- **Testing:** Run `bun test` after changes that affect parsing, conversion, or output.
+- **Output Paths:** Keep OpenCode output at `opencode.json` and `.opencode/{agents,skills,plugins}`.
+- **ASCII-first:** Use ASCII unless the file already contains Unicode.
+
+## Adding a New Target Provider (e.g., Codex)
+
+Use this checklist when introducing a new target provider:
+
+1. **Define the target entry**
+   - Add a new handler in `src/targets/index.ts` with `implemented: false` until complete.
+   - Use a dedicated writer module (e.g., `src/targets/codex.ts`).
+
+2. **Define types and mapping**
+   - Add provider-specific types under `src/types/`.
+   - Implement conversion logic in `src/converters/` (from Claude → provider).
+   - Keep mappings explicit: tools, permissions, hooks/events, model naming.
+
+3. **Wire the CLI**
+   - Ensure `convert` and `install` support `--to <provider>` and `--also`.
+   - Keep behavior consistent with OpenCode (write to a clean provider root).
+
+4. **Tests (required)**
+   - Extend fixtures in `tests/fixtures/sample-plugin`.
+   - Add spec coverage for mappings in `tests/converter.test.ts`.
+   - Add a writer test for the new provider output tree.
+   - Add a CLI test for the provider (similar to `tests/cli.test.ts`).
+
+5. **Docs**
+   - Update README with the new `--to` option and output locations.
+
+## When to Add a Provider
+
+Add a new provider when at least one of these is true:
+
+- A real user/workflow needs it now.
+- The target format is stable and documented.
+- There’s a clear mapping for tools/permissions/hooks.
+- You can write fixtures + tests that validate the mapping.
+
+Avoid adding a provider if the target spec is unstable or undocumented.