feat: support antigravity target in installer

README.md

@@ -2,7 +2,7 @@
 
 # CodeGraph
 
-### Supercharge Claude Code, Cursor, Codex, OpenCode, and Hermes Agent with Semantic Code Intelligence
+### Supercharge Claude Code, Cursor, Codex, OpenCode, Hermes Agent, and Antigravity with Semantic Code Intelligence
 
 **~35% cheaper · ~70% fewer tool calls · 100% local**
 
@@ -19,6 +19,7 @@
 [![Codex CLI](https://img.shields.io/badge/Codex_CLI-supported-blueviolet.svg)](#)
 [![opencode](https://img.shields.io/badge/opencode-supported-blueviolet.svg)](#)
 [![Hermes Agent](https://img.shields.io/badge/Hermes_Agent-supported-blueviolet.svg)](#)
+[![Antigravity](https://img.shields.io/badge/Antigravity-supported-blueviolet.svg)](#)
 
 </div>
 
@@ -41,7 +42,7 @@ npx @colbymchenry/codegraph        # zero-install, or:
 npm i -g @colbymchenry/codegraph
 ```
 
-<sub>CodeGraph bundles its own runtime — nothing to compile, no native build, works the same everywhere. The interactive installer auto-configures your agent(s) — Claude Code, Cursor, Codex CLI, opencode, Hermes Agent.</sub>
+<sub>CodeGraph bundles its own runtime — nothing to compile, no native build, works the same everywhere. The interactive installer auto-configures your agent(s) — Claude Code, Cursor, Codex CLI, opencode, Hermes Agent, and Antigravity.</sub>
 
 ### Initialize Projects
 
@@ -161,7 +162,7 @@ npx @colbymchenry/codegraph
 ```
 
 The installer will:
-- Ask which agent(s) to configure — auto-detects installed ones from: **Claude Code**, **Cursor**, **Codex CLI**, **opencode**, **Hermes Agent**
+- Ask which agent(s) to configure — auto-detects installed ones from: **Claude Code**, **Cursor**, **Codex CLI**, **opencode**, **Hermes Agent**, **Antigravity**
 - Prompt to install `codegraph` on your PATH (so agents can launch the MCP server)
 - Ask whether configs apply to all your projects or just this one
 - Write each chosen agent's MCP server config + an instructions file (e.g. `CLAUDE.md`, `.cursor/rules/codegraph.mdc`, `~/.codex/AGENTS.md`)
@@ -187,7 +188,7 @@ codegraph install --print-config codex               # print snippet, no file wr
 
 ### 2. Restart Your Agent
 
-Restart your agent (Claude Code / Cursor / Codex CLI / opencode / Hermes Agent) for the MCP server to load.
+Restart your agent (Claude Code / Cursor / Codex CLI / opencode / Hermes Agent / Antigravity) for the MCP server to load.
 
 ### 3. Initialize Projects
 
@@ -495,7 +496,7 @@ MIT
 
 <div align="center">
 
-**Made for AI coding agents — Claude Code, Cursor, Codex CLI, opencode, and Hermes Agent**
+**Made for AI coding agents — Claude Code, Cursor, Codex CLI, opencode, Hermes Agent, and Antigravity**
 
 [Report Bug](https://github.com/colbymchenry/codegraph/issues) · [Request Feature](https://github.com/colbymchenry/codegraph/issues)
 

__tests__/installer-targets.test.ts

@@ -493,7 +493,6 @@ describe('Installer targets — partial-state idempotency', () => {
     expect(legacy.mcpServers.codegraph).toBeUndefined();
     expect(legacy.mcpServers.other).toBeDefined();
   });
-
   // ---- Legacy auto-sync hook cleanup ----
   // Pre-0.8 installs wrote `codegraph mark-dirty` / `sync-if-dirty`
   // hooks to settings.json. Both subcommands were removed from the CLI,
@@ -607,6 +606,46 @@ describe('Installer targets — partial-state idempotency', () => {
     // Both events emptied → the whole `hooks` object is removed.
     expect(after.hooks).toBeUndefined();
   });
+
+  it('antigravity: install writes mcp_config.json with correct format', () => {
+    const target = getTarget('antigravity')!;
+    target.install('global', { autoAllow: true });
+
+    const configPath = path.join(tmpHome, '.gemini', 'config', 'mcp_config.json');
+    expect(fs.existsSync(configPath)).toBe(true);
+
+    const content = JSON.parse(fs.readFileSync(configPath, 'utf-8'));
+    expect(content.mcpServers).toBeDefined();
+    expect(content.mcpServers.codegraph).toBeDefined();
+    expect(content.mcpServers.codegraph.command).toBe('codegraph');
+    expect(content.mcpServers.codegraph.args).toEqual(['serve', '--mcp']);
+    expect(content.mcpServers.codegraph.env).toEqual({});
+    expect(content.mcpServers.codegraph.type).toBeUndefined();
+
+    const agentsMd = path.join(tmpHome, '.gemini', 'GEMINI.md');
+    expect(fs.existsSync(agentsMd)).toBe(true);
+  });
+
+  it('antigravity: uninstall removes only mcpServers.codegraph, preserving siblings', () => {
+    const target = getTarget('antigravity')!;
+    const configPath = path.join(tmpHome, '.gemini', 'config', 'mcp_config.json');
+    fs.mkdirSync(path.dirname(configPath), { recursive: true });
+
+    const initialConfig = {
+      mcpServers: {
+        other: { command: 'other-command' }
+      }
+    };
+    fs.writeFileSync(configPath, JSON.stringify(initialConfig, null, 2) + '\n');
+
+    target.install('global', { autoAllow: true });
+    target.uninstall('global');
+
+    const content = JSON.parse(fs.readFileSync(configPath, 'utf-8'));
+    expect(content.mcpServers).toBeDefined();
+    expect(content.mcpServers.other).toEqual({ command: 'other-command' });
+    expect(content.mcpServers.codegraph).toBeUndefined();
+  });
 });
 
 describe('Installer targets — registry', () => {
@@ -616,6 +655,7 @@ describe('Installer targets — registry', () => {
     expect(getTarget('codex')?.id).toBe('codex');
     expect(getTarget('opencode')?.id).toBe('opencode');
     expect(getTarget('hermes')?.id).toBe('hermes');
+    expect(getTarget('antigravity')?.id).toBe('antigravity');
     expect(getTarget('not-a-real-target')).toBeUndefined();
   });
 

src/bin/codegraph.ts

@@ -1341,7 +1341,7 @@ program
  */
 program
   .command('install')
-  .description('Install codegraph MCP server into one or more agents (Claude Code, Cursor, Codex CLI, opencode, Hermes Agent)')
+  .description('Install codegraph MCP server into one or more agents (Claude Code, Cursor, Codex CLI, opencode, Hermes Agent, antigravity)')
   .option('-t, --target <ids>', 'Target agent(s): comma-separated ids, or "auto"|"all"|"none". Default: prompt')
   .option('-l, --location <where>', 'Install location: "global" or "local". Default: prompt')
   .option('-y, --yes', 'Non-interactive: defaults to --location=global --target=auto, auto-allow on')

src/installer/targets/antigravity.ts

@@ -0,0 +1,210 @@
+import * as fs from 'fs';
+import * as path from 'path';
+import * as os from 'os';
+import {
+  AgentTarget,
+  DetectionResult,
+  InstallOptions,
+  Location,
+  WriteResult,
+} from './types';
+import {
+  jsonDeepEqual,
+  readJsonFile,
+  removeMarkedSection,
+  replaceOrAppendMarkedSection,
+  writeJsonFile,
+} from './shared';
+import {
+  CODEGRAPH_SECTION_END,
+  CODEGRAPH_SECTION_START,
+  INSTRUCTIONS_TEMPLATE,
+} from '../instructions-template';
+
+/**
+ * Returns the path to the antigravity configuration directory.
+ * Under ~/.gemini/config
+ */
+function configDir(): string {
+  return path.join(os.homedir(), '.gemini', 'config');
+}
+
+/**
+ * Returns the path to the antigravity MCP configuration JSON file.
+ * Under ~/.gemini/config/mcp_config.json
+ */
+function mcpConfigPath(): string {
+  return path.join(configDir(), 'mcp_config.json');
+}
+
+/**
+ * Returns the path to the GEMINI.md instruction file for antigravity.
+ * Under ~/.gemini/GEMINI.md
+ */
+function instructionsPath(): string {
+  return path.join(os.homedir(), '.gemini', 'GEMINI.md');
+}
+
+/**
+ * Builds the canonical MCP configuration object for antigravity.
+ * Excludes the "type" field and includes "env: {}" as requested.
+ */
+function buildAntigravityMcpConfig(): { command: string; args: string[]; env: Record<string, any> } {
+  return {
+    command: 'codegraph',
+    args: ['serve', '--mcp'],
+    env: {},
+  };
+}
+
+/**
+ * Writes the antigravity MCP entry into ~/.gemini/config/mcp_config.json.
+ * Preserves sibling servers and creates directory/file if they do not exist.
+ */
+function writeMcpEntry(): WriteResult['files'][number] {
+  const file = mcpConfigPath();
+  const dir = path.dirname(file);
+  if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
+
+  const existing = readJsonFile(file);
+  const before = existing.mcpServers?.codegraph;
+  const after = buildAntigravityMcpConfig();
+
+  if (jsonDeepEqual(before, after)) {
+    return { path: file, action: 'unchanged' };
+  }
+
+  const action: 'created' | 'updated' = before ? 'updated' : (fs.existsSync(file) ? 'updated' : 'created');
+  if (!existing.mcpServers) existing.mcpServers = {};
+  existing.mcpServers.codegraph = after;
+  writeJsonFile(file, existing);
+  return { path: file, action };
+}
+
+/**
+ * Writes the markdown agent instructions into ~/.gemini/config/AGENTS.md.
+ * Appends or replaces the section with the CodeGraph markers.
+ */
+function writeInstructionsEntry(): WriteResult['files'][number] {
+  const file = instructionsPath();
+  const dir = path.dirname(file);
+  if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
+
+  const action = replaceOrAppendMarkedSection(
+    file,
+    INSTRUCTIONS_TEMPLATE,
+    CODEGRAPH_SECTION_START,
+    CODEGRAPH_SECTION_END,
+  );
+  const mapped: 'created' | 'updated' | 'unchanged' =
+    action === 'created' ? 'created'
+      : action === 'unchanged' ? 'unchanged'
+        : 'updated';
+  return { path: file, action: mapped };
+}
+
+class AntigravityTarget implements AgentTarget {
+  readonly id = 'antigravity' as const;
+  readonly displayName = 'antigravity';
+  readonly docsUrl = 'https://antigravity.google/download';
+
+  /**
+   * Returns true if the location is supported.
+   * antigravity target only supports global installation.
+   */
+  supportsLocation(loc: Location): boolean {
+    return loc === 'global';
+  }
+
+  /**
+   * Detects whether antigravity target has been installed and configured.
+   */
+  detect(loc: Location): DetectionResult {
+    if (loc !== 'global') {
+      return { installed: false, alreadyConfigured: false };
+    }
+    const mcpPath = mcpConfigPath();
+    const config = readJsonFile(mcpPath);
+    const alreadyConfigured = !!config.mcpServers?.codegraph;
+    const installed = fs.existsSync(path.join(os.homedir(), '.gemini')) || fs.existsSync(mcpPath);
+    return { installed, alreadyConfigured, configPath: mcpPath };
+  }
+
+  /**
+   * Installs codegraph MCP configurations and instructions for antigravity.
+   */
+  install(loc: Location, _opts: InstallOptions): WriteResult {
+    if (loc !== 'global') {
+      return {
+        files: [],
+        notes: ['antigravity has no project-local config — re-run with --location=global to install.'],
+      };
+    }
+    const files: WriteResult['files'] = [];
+
+    files.push(writeMcpEntry());
+    files.push(writeInstructionsEntry());
+
+    return {
+      files,
+      notes: ['Restart antigravity for MCP changes to take effect.'],
+    };
+  }
+
+  /**
+   * Uninstalls codegraph configurations and instructions for antigravity.
+   */
+  uninstall(loc: Location): WriteResult {
+    if (loc !== 'global') return { files: [] };
+    const files: WriteResult['files'] = [];
+
+    const mcpPath = mcpConfigPath();
+    const config = readJsonFile(mcpPath);
+    if (config.mcpServers?.codegraph) {
+      delete config.mcpServers.codegraph;
+      if (Object.keys(config.mcpServers).length === 0) {
+        delete config.mcpServers;
+      }
+      writeJsonFile(mcpPath, config);
+      files.push({ path: mcpPath, action: 'removed' });
+    } else {
+      files.push({ path: mcpPath, action: 'not-found' });
+    }
+
+    const instr = instructionsPath();
+    const action = removeMarkedSection(instr, CODEGRAPH_SECTION_START, CODEGRAPH_SECTION_END);
+    files.push({ path: instr, action });
+
+    return { files };
+  }
+
+  /**
+   * Prints the configuration snippet for manual pasting.
+   */
+  printConfig(loc: Location): string {
+    if (loc !== 'global') {
+      return '# antigravity has no project-local config — use --location=global.\n';
+    }
+    const target = mcpConfigPath();
+    const snippet = JSON.stringify(
+      {
+        mcpServers: {
+          codegraph: buildAntigravityMcpConfig(),
+        },
+      },
+      null,
+      2
+    );
+    return `# Add to ${target}\n\n${snippet}\n`;
+  }
+
+  /**
+   * Returns list of paths created/modified by this target.
+   */
+  describePaths(loc: Location): string[] {
+    if (loc !== 'global') return [];
+    return [mcpConfigPath(), instructionsPath()];
+  }
+}
+
+export const antigravityTarget: AgentTarget = new AntigravityTarget();

src/installer/targets/registry.ts

@@ -13,13 +13,15 @@ import { cursorTarget } from './cursor';
 import { codexTarget } from './codex';
 import { opencodeTarget } from './opencode';
 import { hermesTarget } from './hermes';
+import { antigravityTarget } from './antigravity';
 
 export const ALL_TARGETS: readonly AgentTarget[] = Object.freeze([
   claudeTarget,
   cursorTarget,
   codexTarget,
   opencodeTarget,
   hermesTarget,
+  antigravityTarget,
 ]);
 
 export function getTarget(id: string): AgentTarget | undefined {

src/installer/targets/types.ts

@@ -19,7 +19,7 @@ export type Location = 'global' | 'local';
  * lookup. New targets add a value here when they're added to the
  * registry. Keep these short and lowercase.
  */
-export type TargetId = 'claude' | 'cursor' | 'codex' | 'opencode' | 'hermes';
+export type TargetId = 'claude' | 'cursor' | 'codex' | 'opencode' | 'hermes' | 'antigravity';
 
 /**
  * Result of `target.detect(location)`.