[aledog007]

Problem

On Intel Macs, installing the Antigravity ACP runtime from provider settings sticks at "Checking the downloaded runtime" and then fails with the generic "Could not install Antigravity. Check free disk space…" error. The download, SHA-256 check, and extraction all succeed. The runtime then never answers ACP initialize, so validation times out after 90 seconds.

Cause: Google signs the darwin-x64 agy_acp_server.par and localharness_external (1.4.5) with the hardened runtime (flags=0x10000(runtime)) and no entitlements. The runtime is a bundled Python program. On x86_64 its libffi needs writable+executable memory for closures. Hardened runtime refuses that, so libffi falls back to dlmmap_locked → open_temp_exec_file_dir and retries temp-file mappings forever. A sample of the hung process shows it spinning in open/unlink/mmap under dlmmap_locked. Run by hand, it printed nothing in 400 seconds. Apple Silicon is unaffected because libffi there doesn't need writable executable memory.

Fix

On darwin-x64 only, after the SHA-256 check passes and before validation, re-sign both binaries ad hoc with /usr/bin/codesign --force --sign -. This keeps the integrity check against Google's pinned hash and drops only the hardened-runtime flag. Re-signing changes file sizes, so the install record now stores the sizes measured after signing. Without that, completedRelease would reject the installed files.

Verification

• New test in AntigravityInstallation.test.ts (darwin/x64 harness with a fake spawner): it asserts the codesign invocation and that resolve() accepts the re-signed sizes. It fails on main.
• Manual check: on an i7-9750H Mac, the original binary never answered initialize. An ad-hoc re-signed copy answered in about 11 seconds with antigravity-acp 1.4.5.
• End to end: makeAntigravityInstallation with the real release asset and default validation on the same Mac went downloading → extracting → verifying → succeeded (1.4.5), and resolve() returned the managed runtime.
• vp run check:changed passes.

Chat sessions spawn the same managed executable, so they're covered too. Linux, Windows, and darwin-arm64 are unchanged.

Done with Claude Opus 5.5 in Claude Code (running in T3 Code).

🤖 Generated with Claude Code

[macroscopeapp]

Approvability

Verdict: Needs Human Approval

Macroscope's review found this PR requires human approval — The fix enables Intel Mac installations by ad-hoc re-signing the runtime and harness, removing their hardened-runtime protections. Human judgment is needed on that security tradeoff; download integrity checks and successful installation verification do not cover the loss of runtime defenses.

^{You can add or adjust custom eligibility rules. Learn more.}

[coderabbitai]

No actionable comments were generated in the recent review.

Walkthrough

On macOS x64, Antigravity installation signs the extracted executable and harness before validation. A nonzero signing exit code fails extraction. Installed-release records use the extracted files’ observed sizes.

Changes: Antigravity installation

Layer / File(s)	Summary
Signing and release metadata apps/server/src/provider/AntigravityInstallation.ts, apps/server/src/provider/AntigravityInstallation.test.ts	The installer runs ad hoc codesign on both extracted files on macOS x64 and fails extraction on a nonzero exit code. It records each file’s observed size. The test injects a mocked spawner and checks the signing command, successful installation, and modified executable contents.

Estimated code review effort: 2 (Simple) | ~12 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant AntigravityInstallation
  participant ChildProcessSpawner
  participant codesign
  AntigravityInstallation->>ChildProcessSpawner: Spawn codesign for extracted executable and harness
  ChildProcessSpawner->>codesign: Run ad hoc signing command
  codesign-->>ChildProcessSpawner: Return exit status
  ChildProcessSpawner-->>AntigravityInstallation: Provide process result
  AntigravityInstallation->>AntigravityInstallation: Validate paths and record observed file sizes

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Possibly related PRs

• pingdotgg/t3code#21249: Adds upstream Antigravity releases to the managed installation and validation flow, which this change also updates.

Suggested labels: bugfix

Suggested reviewers: juliusmarminge, macroscopeapp

Merge Risk: Minimal · up to 66627

Intel Mac installations are re-signed and checked for reuse. No merge-blocking risk was established.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title clearly describes the Intel Mac installation fix.
Description check		The description is mostly complete. It explains the problem, fix, and verification. Add a Scope and approval section with an approved issue or discussion, or explain why the fix qualifies without one.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Finishing Touches

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Recent review info

Run configuration

• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: main
• File: .coderabbit.config.ts
• Commit: e21347b
• Layers: Repository TS config
• Review profile: CHILL
• Plan: Advanced
• Run ID: e0be7c6c-f6f7-4eb5-9146-973404809b22

Commits

Reviewing files that changed from the base of the PR and between 56a479c and 66627be.

Files selected for processing: 1

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

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[aledog007]

On the hardened-runtime tradeoff Macroscope flagged:

• The integrity check is unchanged. The archive must still match Google's pinned SHA-256 before anything is re-signed, so we only ever sign bytes Google shipped.
• This applies only to darwin-x64. arm64, Linux and Windows keep Google's original signatures.
• Keeping the hardened runtime isn't a working option on Intel. Without an entitlement for writable+executable memory, libffi never gets past startup, so the runtime can't answer initialize at all. An ad hoc signature is the only way to drop that flag without patching the binary.
• The re-signed binaries run under the same user and environment T3 already gives them. The custom-path and PATH sources aren't touched.

If Google ships a darwin-x64 build with com.apple.security.cs.allow-unsigned-executable-memory or without the hardened runtime, this branch can be removed.