core: add support for user defined event hooks

[bhandras]

This PR adds support for user defined event hooks (similar feature to what already exists in Claude Code).

It's an attempted fix for: #2109

See the second commit for usage and example configuration!

[github-actions]

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[bhandras]

I have read the CLA Document and I hereby sign the CLA

[bhandras]

recheck

[bhandras]

Rebased on top of latest main branch.

[bhandras]

@bolinfest do you see any chance of this landing? Would you mind PTAL?

[bhandras]

Rebased on latest main.

[tommyengstrom]

Please review this. Hooks are a big deal! Would be great if we could get them in Codex.

[bhandras]

Ping @bolinfest, could you PTAL? Seems like many are interested in this feature.

[bbss]

I've been using this PR and it's useful, so thanks. However it does not allow blocking on these actions or controlling flow like claude code hooks do.

[pavelklymenko]

I've been using this PR and it's useful, so thanks. However it does not allow blocking on these actions or controlling flow like claude code hooks do.

It would be awesome to be able to “facilitate” good behavior 😁

[andrewschreiber]

Excited for this!

[Djordje-Stojanovic]

Can't wait for this :)

[bhandras]

Rebased!

[backnotprop]

However it does not allow blocking on these actions or controlling flow like claude code hooks do.

This is the point, we need this.

[DenisGorbachev]

However it does not allow blocking on these actions or controlling flow like claude code hooks do.

Agreed, this is very much needed. Currently I'm asking the model to run mise agent:on:stop, which runs the lints and tests.