Google Antigravity Memory
Automatic long-term memory for Google Antigravity — AGY, the AGY IDE, and the AGY CLI: one degit command installs a full plugin bundle whose lifecycle hooks inject recalled context and capture the durable facts in your prompts, with the MemorySync MCP server, four skills, and an always-on recall rule. Node hooks: native on Windows, macOS, and Linux.
What the plugin provides
| Layer | What it does |
|---|---|
| Hooks (recall + capture) | SessionStart injects your profile and project context; UserPromptSubmit recalls per prompt and sends your prompt for fact extraction in a detached process — only the durable facts in it are stored; Stop sends nothing, because replies are not stored. Dependency-free Node scripts with per-hook timeouts and exit-0 discipline. |
| MCP servers | The full MemorySync memory server (API key via ${MEMORYSYNC_API_KEY} interpolation, or OAuth via Antigravity’s dynamic client registration) plus the zero-auth docs server. |
| Skills + rule | Four skills (memory conventions, remember, recall, status) auto-discovered at session start, and an always-on rule that keeps recall alive through the MCP tools. |
| Plugin bundle | Antigravity’s own format — plugin.json, mcp_config.json, hooks.json, skills/, rules/ — one folder, one install command. |
| Mem0 | Supermemory | Zep | MemorySync | |
|---|---|---|---|---|
| Antigravity integration exists | ✓ plugin | ✗ generic MCP only | ✗ Composio bridge only | ✓ plugin |
| Hooks run natively on Windows | ✗ bash-only — on a platform whose IDE ships for Windows | — | — | ✓ Node on all three OS |
Correct serverUrl config documented | ✓ | ✗ their snippet uses url — Antigravity reads serverUrl | — | ✓ with the trap called out |
| Uninstall actually documented | ✗ cache dirs never mentioned | — | — | ✓ including the MCP cache directories |
| Session-safe failure contract | ❌ \|\| true shell guards | — | — | ✓ every script exits 0 on every path, tested |
Install
# Get an API key at https://app.memorysync.io, then:# macOS/Linux: export MEMORYSYNC_API_KEY=ms_...# Windows: setx MEMORYSYNC_API_KEY ms_...
Option A: Full plugin (recommended)
# Hooks + skills + rule + MCP, all workspaces:npx degit memorysyncio/memorysync-plugins/antigravity ~/.gemini/config/plugins/memorysync# then restart Antigravity. Workspace-scoped instead:# <workspace>/.agents/plugins/memorysync
Option B: MCP only
{ "mcpServers": { "memorysync": {"serverUrl": "https://mcp.memorysync.io/mcp","headers": { "X-API-Key": "${MEMORYSYNC_API_KEY}" } } } }
Settings → Customizations → Installed MCP Servers → Add MCP → View raw config edits the same file. Antigravity’s remote-server field is `serverUrl` — not url; configs copied from other tools’ docs silently fail on this. Drop the headers block to sign in with OAuth instead (Antigravity registers itself dynamically and opens the browser). Hooks require Node.js ≥ 18 on PATH. The AGY CLI manages servers with /mcp in the prompt panel.
What runs when
| Moment | What happens |
|---|---|
| Session start | Recalls your profile and this project’s context, injected as additional context. |
| Every prompt | Sends your prompt for fact extraction in a detached process — zero added latency, one add per prompt. Only the durable facts in it are stored. Prompts of 24 characters or more also recall memories relevant to the prompt. |
| Reply finishes (Stop) | Nothing is sent — replies are not stored. |
| Any failure — no key, network down, monthly quota exhausted | Silent skip, exit 0. Memory can never break an Antigravity session, by contract and by test. |
Identity and scope resolve like every MemorySync surface: MEMORYSYNC_USER_ID (default: OS username), project from the git remote — worktree-aware — with MEMORYSYNC_PROJECT override. Facts captured here carry the antigravity:: session key plus the project, and a retried or redelivered hook is recognised server-side, so a prompt’s facts are extracted once.
Uninstalling cleanly
Removing the plugin folder or the MCP entry is not enough for AGY and the AGY IDE — they cache MCP servers on disk. Also delete the cache directories: ~/.gemini/antigravity/mcp/memorysync/, ~/.gemini/antigravity-ide/mcp/memorysync/, and ~/.gemini/antigravity-cli/mcp/memorysync/. The AGY CLI notices removals fastest. No other memory vendor documents this.
Supported versions
| Surface | Requires | Verified on |
|---|---|---|
memorysync Antigravity plugin 1.1.0 | Antigravity 2.0+ (AGY / AGY IDE / AGY CLI), Node.js 18+ | Hook contract suite 52/52 — antigravity platform shapes, prompts sent and replies never sent, both monthly-quota server modes, and a bundle-integrity test that fails CI if the bundle ever drifts from the tested scripts |
The hook payloads follow the Claude-shaped contract Mem0’s plugin also relies on (their scripts literally set CLAUDE_PLUGIN_ROOT); if Antigravity ever drops those events, the documented PreInvocation/injectSteps path is the fallback and every script already exits 0 regardless.