Antigravity agent silently dies when workspace repo has extensions.worktreeconfig=true with core.repositoryformatversion=0

Google Antigravity
1

Antigravity 1.107.0 on macOS becomes completely unresponsive to prompts — the
input accepts text but pressing send produces no response and no user-facing
error — when an opened workspace has an inconsistent git config that the
system git CLI tolerates but Antigravity’s bundled language server rejects.

The agent’s language-server RPCs (GetAllSkills, GetAgentScripts,
workspace-info resolution) all fail with core.repositoryformatversion does not
support extension: worktreeconfig, leaving the agent with workspace infos is
nil. The UI gives no indication anything is wrong; it just doesn’t respond.

Environment

  • Antigravity 1.107.0 (Electron 39.2.3)
  • macOS (Apple Silicon)
  • Apple Git 2.50.1 (the system git, which silently tolerates the misconfig)
  • Workspaces are standard Git repositories that contain .claude/worktrees/
    subdirectories created by other agentic tools (Claude Code), which
    auto-enabled extensions.worktreeconfig without bumping
    core.repositoryformatversion to 1

Symptom

  • Agent panel (“create prompt”) accepts input but produces zero response on
    send
  • No error toast, no spinner, no user-visible diagnostic
  • App otherwise behaves normally (terminal, file editor, language services all
    work)
  • Persists across relaunches; persists for over a week in my case

Root cause

The opened workspace’s .git/config has the combination:

[core]
repositoryformatversion = 0
[extensions]
worktreeconfig = true

Per the git repository-format spec, any extensions.* setting requires
repositoryformatversion >= 1. Apple Git 2.50.1 ignores this contradiction, so
git status, git pull, git worktree list all work normally. Antigravity’s
bundled Go-based git library is strict and refuses to open the repo.

Evidence (from ~/Library/Application Support/Antigravity/logs//)

ls-main.log (the language-server stderr):

E0427 … interceptor.go:74]
/exa.language_server_pb.LanguageServerService/GetAllSkills (unknown):
core.repositoryformatversion does not support extension: worktreeconfig
E0427 … interceptor.go:74]
/exa.language_server_pb.LanguageServerService/GetAgentScripts (unknown):
core.repositoryformatversion does not support extension: worktreeconfig
W0427 … cascade_manager.go:2512] Failed to resolve workspace infos,
continuing without:
core.repositoryformatversion does not support extension: worktreeconfig
E0427 … log.go:398] non-fatal: failed to resolve workspace infos for
cascade: …worktreeconfig
E0427 … log.go:398] failed to check terminal shell support: internal:
internal error
E0427 … log.go:398] workspace infos is nil

agent-window-console.log (renderer side, repeated 30+ times in 16s before
giving up):

[Manager] Error fetching workflows, skills, and MCP prompts: ConnectError:
[unknown]
core.repositoryformatversion does not support extension: worktreeconfig

Reproduction

cd /tmp && mkdir agbug && cd agbug
git init
git config extensions.worktreeconfig true

leave core.repositoryformatversion at its default 0

echo hi > a.txt && git add . && git commit -m init

Open the directory in Antigravity. Try to send a prompt to the agent. Nothing
will happen.

Workaround

git -C config --unset extensions.worktreeconfig

(Safe if no .git/config.worktree file exists — i.e., no actual per-worktree
config is in use.) Then Cmd+Shift+P → Developer: Reload Window. Agent
immediately becomes responsive.

Alternative: git -C config core.repositoryformatversion 1 if you
actually want to keep worktree-specific config.

Suggested fixes (Antigravity side)

  1. Surface the error to the user. The single most important fix. The agent
    panel should display “Couldn’t read workspace git metadata: …” instead of
    silently doing nothing. This bug would have been a 30-second self-diagnosis if
    any error had been visible.
  2. Tolerate the misconfiguration. Apple’s git and most users’ git silently
    ignore this. The bundled Go git library should either downgrade the error to a
    warning or auto-repair (extensions.worktreeconfig=true +
    repositoryformatversion=0 is unambiguously fixable by bumping the version).
  3. Detect and offer to repair on workspace open. A one-click “Fix git config”
    prompt would close this entirely. Especially since other agentic tools (Claude
    Code, etc.) routinely produce this state via git worktree add.
  4. Don’t let workspace-introspection failure block the agent input. Fall back
    to “no skills / no MCP prompts available” rather than non-functional.