feat: add firebender checkpoint preset alias

[anishfish2]

Summary

• add firebender as a first-class git-ai checkpoint preset alias backed by the existing ai_tab payload schema (before_edit / after_edit)
• preserve firebender as the tool label in agent metadata so downstream attribution reflects the actual agent
• update CLI help text and test preset recognition to include firebender
• add integration coverage validating Firebender alias attribution end-to-end

Test plan

• Run integration flow with checkpoint firebender --hook-input ... for before_edit and after_edit
• Commit and verify new lines are attributed as AI in blame assertions
• Confirm existing ai_tab behavior remains unchanged

---

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 3 additional findings.

[svarlamov]

Thanks for the contribution @anishfish2! Quick question, can you point me in the right direction for the docs on Firebender hooks? It looks like the hook names in the mdm hooks setup are the same as Cursor's hooks, but they are actually the old cursor hooks format. Any instructions re how to test, etc. would be helpful. Thanks

[kevo1ution]

hey @svarlamov these are the firebender docs on hooks https://docs.firebender.com/multi-agent/hooks.

for testing, you can download the plugin from https://plugins.jetbrains.com/plugin/25224-firebender/ on intellij. if you send an email to kevin@firebender.com, I can temporarily white list your account

[svarlamov]

Hey @kevo1ution that sounds great. I think this PR may have been authored just before we cut our Cursor agent preset over to using the preToolUse/postToolUse hooks. That's how all the rest of our agent impls work as well, but Cursor was a one-off as they didn't support the pre/post tool use hooks until somewhat recently. Do you have bandwidth to update this PR to that new flow? Let me know if there's anything I can help with/explain there.

Excited to add Firebender support to Git AI

[kevo1ution]

Yep I can take a look to scope out the work @svarlamov , thanks for the feedback!

[kevo1ution]

Superseded by draft PR #917 from a maintained branch because the original head branch is stale. Continuing follow-up work there.