I maintain a repo that targets all three runtimes and keeps a parity matrix. Here are the three gaps that cost the most time, and what to do about each.

Will my hooks still block what they blocked before?

Not always. On Claude Code, a PreToolUse hook runs before the tool and can stop it. That is a real guardrail. On Windsurf, Cascade Hooks fire after the agent acts, so they can flag or revert, but they never prevent. Codex runs command hooks, but currently parses and skips prompt and agent hooks. A hook that blocks a dangerous command on one runtime only logs it on another.

Will my skills trigger the same way?

The SKILL.md body ports. The trigger does not. Claude Code auto-invokes a skill from its description. Codex makes implicit invocation a switch: turn allow_implicit_invocation off and the skill runs only when you type $skill yourself. Codex also reads skills from a different path. The skill still works. It just may never fire on its own.

Can I publish a plugin once and install it everywhere?

No. Claude Code, Codex, and Windsurf each have their own manifest, catalog, and versioning. One plugin means three manifests to maintain and three install paths to test. "Publish once, install everywhere" is a slogan, not a workflow. Budget distribution as a per-runtime cost.

What to do

1. Keep a parity matrix. Write down what you have verified on each runtime. Treat the rest as unknown, not assumed.

2. Re-test on every runtime, especially any hook that enforces a security rule.

3. Budget distribution per runtime, not once.

FAQ

Do skills written for Claude Code work in Codex? The SKILL.md body usually does. The discovery path and the invocation policy need adjusting per runtime.

Which runtime has the strongest hook guarantee? Claude Code. Its PreToolUse hook can block a tool call before it runs. Treat hooks on the other runtimes as observe-and-react.

The parity matrix I keep is public, in the repo: github.com/alex-voloshin-dev/ai-skills. If you run more than one of these runtimes, start your own.