fix(server): distinguish the Antigravity CLI from the missing ACP runtime

[Marve10s]

What Changed

When no Antigravity ACP runtime is found, the provider status now checks whether the agy CLI is on PATH. If it is, the status reads:

The Antigravity CLI is installed, but T3 Code runs the separate Antigravity ACP agent. Install it in this environment or set a custom executable path.

The existing "Antigravity is not installed" message is unchanged for machines without the CLI. Resolution order, managed installs, PATH lookup of agy_acp_server.par, and the custom binary path override all behave as before.

Why

The Antigravity provider runs Google's agy_acp_server.par ACP agent, not the agy CLI. Anyone who already uses the CLI sees "Antigravity is not installed" next to a tool they installed and use daily, which reads as a detection bug rather than a setup step. The provider has no way to say "you have the wrong binary", so users go looking for a PATH or permissions problem instead of pressing Install in Settings > Providers.

The message is the only thing that is wrong here. The alternative would be to accept the CLI as a runtime and drive it directly, which is what #3056 originally asked for. That path is far more complex: the CLI has no ACP mode, print mode cannot surface permission prompts, and events would have to come from undocumented transcript files. #9348 deliberately chose the official ACP agent instead, so this change keeps that design and only makes the status honest about which binary is missing.

Summary by CodeRabbit

Bug Fixes

• Bug Fixes
  • Improved Antigravity installation detection across supported platforms.
  • Added clearer error details when the Antigravity CLI is installed but its required ACP agent is unavailable.
  • Clarified error messaging when Antigravity is not installed.

[cursor]

Bugbot is paused — on-demand spend limit reached

Bugbot uses usage-based billing for this team and has hit its on-demand spend limit.

A team admin can raise the spend limit in the Cursor dashboard, or wait for the next billing cycle to continue.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-09T12:40:12.020676Z	70d232f	New commits

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review" or "@codex security review".

Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings.

[macroscopeapp]

Approvability

Verdict: Would Approve

Macroscope's review found this PR approvable — This is a narrowly scoped server-side diagnostic fix that distinguishes an installed Antigravity CLI from the separate ACP runtime without changing successful resolution or installation paths. A known medium-severity POSIX empty-PATH edge case remains independently blocking under the repository’s correctness policy.

Not approved because:

• 1 blocking correctness issue found at or above your repo's Minimum Blocking Severity

^{Adjust the Minimum Blocking Severity for this repo — including turning it Off — in Settings. You can add or adjust custom eligibility rules. Learn more.}

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Advanced

Run ID: c887aa7e-074d-481f-9b97-974bb8451646

📥 Commits

Reviewing files that changed from the base of the PR and between 29da082 and 70d232f.

📒 Files selected for processing (2)

• apps/server/src/provider/AntigravityInstallation.test.ts
• apps/server/src/provider/AntigravityInstallation.ts

Included review availability: Your plan provides up to 10 included reviews per hour; 8 remain after this review.

---

📝 Walkthrough

Walkthrough

The Antigravity installation resolver now uses the shared isCommandAvailable helper for agy detection. It reports separate details when only the CLI is installed or when no Antigravity binary is available. A Windows-skipped test covers both cases.

Changes

Antigravity installation resolution

Layer / File(s)	Summary
CLI detection and ACP error handling apps/server/src/provider/AntigravityInstallation.ts, apps/server/src/provider/AntigravityInstallation.test.ts	The resolver uses injected platform, filesystem, and path services with isCommandAvailable("agy"). When only the CLI is available, it returns the separate ACP-agent installation error. The test verifies distinct details for CLI-only and empty PATH cases.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 70d23

Antigravity status now distinguishes an installed CLI from a missing ACP agent, giving users the correct installation guidance while preserving existing resolution behavior. No current merge-blocking risk remains.

Suggested reviewers: juliusmarminge, t3dotgg

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely identifies the main change: distinguishing the Antigravity CLI from the missing ACP runtime.
Description check	✅ Passed	The description includes complete What Changed and Why sections and explains the unchanged behavior and scope. The optional UI Changes section is not applicable. The Checklist section is missing, but …
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 2…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

_{Comment @coderabbitai help to get the list of available commands.}

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 29da082724

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".