Migrating Claude Code → Antigravity CLI

Run agy-migrate (dry-run) → read the report → agy-migrate --apply. agy-migrate --uninstall --apply reverses everything.

The tool treats the Claude Code config dir as read-only. The single exception is an AGENTS.md symlink placed beside an existing CLAUDE.md, and only under --include-repos.

Where the two products keep things

Claude Code — ~/.claude/ plus ~/.claude.json, relocatable together via CLAUDE_CONFIG_DIR. Two things surprise people: there is usually no ~/.claude/CLAUDE.md, and auto-memory is per project, under ~/.claude/projects/<encoded-cwd>/memory/. The encoding maps /, _ and . all to -, so it can only be matched forward (re-encode a known path), never decoded.

Claude Desktop / Cowork is a separate universe. It has its own ~/Library/Application Support/Claude/claude_desktop_config.json (MCP) and Claude Extensions/ (.mcpb), and its Cowork skills are server-synced into local-agent-mode-sessions/skills-plugin/, so no local original exists to migrate. Only claude_desktop_config.json's mcpServers is portable, and the tool picks it up. The bundled claude-code/<version>/claude.app inside the desktop app is the ordinary CLI and does read ~/.claude.

Antigravity — rooted at ~/.gemini/, not ~/.antigravity:

So customization is shared across surfaces; session state is not.

What moves, and how

Cannot move

Session transcripts. Claude Code writes plain JSONL; Antigravity writes one SQLite database per conversation whose payloads are opaque protobuf blobs (steps.metadata, gen_metadata.data, …). There is no supported writer. Also unmovable: tasks/, plans/, file-history/, jobs/, and credentials (different auth systems entirely — never copy these).

Four behaviours that will bite you

These are measured against agy 1.1.12, and none of them are documented.

1. A rule without trigger: always_on is silently ignored. No error, no warning. Only bare AGENTS.md / GEMINI.md are always-on without frontmatter. Migrated memory is therefore rewritten with frontmatter, never stripped of it.
2. Workspace .agents/ only loads when the session is bound to an agy project — and registering one is not enough for headless runs. agy -p always uses the id in antigravity-cli/cache/default_project_id.txt (default-cli-project out of the box) regardless of cwd. The tool registers each repo and prints the id; run agy --project <id> there, or pick the project in the TUI. Global ~/.gemini/config/ loads regardless, which is why global memory goes to a plugin.
3. ~/ is not expanded in the global skills.json. Entry paths must be absolute.
4. Rules and workflows are capped at 12,000 characters per file. Oversized memory is split into -1.md, -2.md parts on paragraph boundaries.

What the native importer gets wrong

agy plugin import claude exists and handles skills, agents, commands, hooks and MCP — but:

• It only scans ~/.claude/plugins/<name>/ one level deep, which no Claude Code 2.x install matches (plugins live under plugins/cache/<marketplace>/<plugin>/<version>/), so on a real machine it prints No claude extensions found. and exits 0. It also does not follow symlinks, so the staging HOME must contain real copies.
• It destroys remote MCP servers: {"type":"http","url":…} becomes {"command":"","args":null} — the URL is dropped and no serverUrl is written.
• It copies hooks verbatim. Antigravity's hooks.json is a map of named hooks ({"my-hook": {"PreToolUse": [...]}}), its matchers are step-type names (run_command, not Bash), and it fires only PreToolUse, PostToolUse, PreInvocation, PostInvocation, Stop — SessionStart, SessionEnd, PreCompact, Notification and SubagentStop have no equivalent. ${CLAUDE_PLUGIN_ROOT} is never set, so hook commands referencing it break.

agy-migrate runs the importer anyway (so the output tracks Google's format), then repairs all three and drops the leftovers it copies.

Permissions widen the grant — always review

Claude's permissions.allow stores whole command lines, quoted prompts included, not command prefixes. They cannot map 1:1 onto agy's command(), which matches on a prefix. The tool keeps the executable plus one plain sub-word (Bash(git diff:*) → command(git diff)), absorbs redundant prefixes, and drops entries whose executable position holds a variable or shell metacharacter.

That is strictly a widening. So the result is written to ~/.gemini/.agy-migrate/proposed-permissions.json for review, and merged into settings.json only with --apply-permissions.

Also not migrated, by design: model (no Gemini equivalent for a Claude model id), effortLevel (agy's --effort is a per-session flag, low|medium|high only), and env (Anthropic/Vertex routing that means nothing to agy).

Flags

Re-running is safe: generated files carry a marker comment, and a file whose marker you deleted is treated as yours and left alone.