diff --git a/CHANGELOG.md b/CHANGELOG.md
index d2ae567d0..4b2d3925a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,9 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
+### New Features
+
+- `codegraph install` now supports GitHub Copilot CLI as a target (`--target=copilot`). Running the installer writes the MCP server entry to `~/.copilot/mcp-config.json` (global) or `.github/mcp.json` in the project root (local), making CodeGraph available immediately in `copilot` sessions.
 
 ## [1.5.0] - 2026-07-21
 
diff --git a/__tests__/installer-targets.test.ts b/__tests__/installer-targets.test.ts
index 6db793d65..e4c35ab9a 100644
--- a/__tests__/installer-targets.test.ts
+++ b/__tests__/installer-targets.test.ts
@@ -501,6 +501,57 @@ describe('Installer targets — partial-state idempotency', () => {
     expect(paths.some((p) => p.endsWith('/.kiro/steering/codegraph.md'))).toBe(false);
   });
 
+  it('copilot: global install writes ~/.copilot/mcp-config.json (mcpServers.codegraph)', () => {
+    const copilot = getTarget('copilot')!;
+    const result = copilot.install('global', { autoAllow: true });
+    expect(result.files.length).toBe(1);
+    expect(result.files[0].action).toBe('created');
+    expect(result.files[0].path).toMatch(/\.copilot[/\\]mcp-config\.json$/);
+    const cfg = JSON.parse(fs.readFileSync(result.files[0].path, 'utf-8'));
+    expect(cfg.mcpServers.codegraph).toEqual({ type: 'local', command: 'codegraph', args: ['serve', '--mcp'], tools: ['*'] });
+  });
+
+  it('copilot: local install writes .github/mcp.json (mcpServers.codegraph)', () => {
+    const copilot = getTarget('copilot')!;
+    const result = copilot.install('local', { autoAllow: true });
+    expect(result.files.length).toBe(1);
+    expect(result.files[0].action).toBe('created');
+    expect(result.files[0].path.replace(/\\/g, '/')).toMatch(/\/\.github\/mcp\.json$/);
+    const cfg = JSON.parse(fs.readFileSync(result.files[0].path, 'utf-8'));
+    expect(cfg.mcpServers.codegraph).toEqual({ type: 'local', command: 'codegraph', args: ['serve', '--mcp'], tools: ['*'] });
+  });
+
+  it('copilot: install preserves pre-existing sibling in mcpServers', () => {
+    const copilot = getTarget('copilot')!;
+    const mcpFile = path.join(tmpHome, '.copilot', 'mcp-config.json');
+    fs.mkdirSync(path.dirname(mcpFile), { recursive: true });
+    fs.writeFileSync(mcpFile, JSON.stringify({
+      mcpServers: { other: { type: 'local', command: 'other', args: [], tools: ['*'] } },
+    }, null, 2) + '\n');
+
+    copilot.install('global', { autoAllow: true });
+
+    const after = JSON.parse(fs.readFileSync(mcpFile, 'utf-8'));
+    expect(after.mcpServers.other).toBeDefined();
+    expect(after.mcpServers.codegraph).toBeDefined();
+  });
+
+  it('copilot: uninstall strips codegraph but leaves sibling servers intact', () => {
+    const copilot = getTarget('copilot')!;
+    const mcpFile = path.join(tmpHome, '.copilot', 'mcp-config.json');
+    fs.mkdirSync(path.dirname(mcpFile), { recursive: true });
+    fs.writeFileSync(mcpFile, JSON.stringify({
+      mcpServers: { other: { type: 'local', command: 'other', args: [], tools: ['*'] } },
+    }, null, 2) + '\n');
+
+    copilot.install('global', { autoAllow: true });
+    copilot.uninstall('global');
+
+    const after = JSON.parse(fs.readFileSync(mcpFile, 'utf-8'));
+    expect(after.mcpServers.other).toBeDefined();
+    expect(after.mcpServers.codegraph).toBeUndefined();
+  });
+
   it('antigravity: install writes to LEGACY ~/.gemini/antigravity/mcp_config.json when no migration marker', () => {
     const antigravity = getTarget('antigravity')!;
     antigravity.install('global', { autoAllow: true });
@@ -673,8 +724,7 @@ describe('Installer targets — partial-state idempotency', () => {
     expect(result.notes?.join(' ')).toMatch(/no project-local config/);
   });
 
-  it('antigravity: does not write GEMINI.md (only gemini target owns instructions)', () => {
-    const antigravity = getTarget('antigravity')!;
+  it('antigravity: does not write GEMINI.md (only gemini target owns instructions)', () => {    const antigravity = getTarget('antigravity')!;
     antigravity.install('global', { autoAllow: true });
     const geminiMd = path.join(tmpHome, '.gemini', 'GEMINI.md');
     expect(fs.existsSync(geminiMd)).toBe(false);
diff --git a/src/installer/targets/copilot.ts b/src/installer/targets/copilot.ts
new file mode 100644
index 000000000..8a5362704
--- /dev/null
+++ b/src/installer/targets/copilot.ts
@@ -0,0 +1,131 @@
+/**
+ * GitHub Copilot CLI target.
+ *
+ *   - MCP server entry to `~/.copilot/mcp-config.json` (global) or
+ *     `.github/mcp.json` in the project root (local) under the standard
+ *     `mcpServers.codegraph` key.
+ *
+ * The Copilot CLI config uses `type: "local"` and requires a `tools` array
+ * (use `["*"]` to enable all tools). Both fields are mandatory for the CLI
+ * to start the server.
+ *
+ * Docs: https://docs.github.com/en/copilot/how-tos/copilot-cli/customize-copilot/add-mcp-servers
+ */
+
+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,
+  writeJsonFile,
+} from './shared';
+
+function globalConfigDir(): string {
+  return path.join(os.homedir(), '.copilot');
+}
+
+function globalMcpPath(): string {
+  return path.join(globalConfigDir(), 'mcp-config.json');
+}
+
+function localMcpPath(): string {
+  return path.join(process.cwd(), '.github', 'mcp.json');
+}
+
+function mcpPath(loc: Location): string {
+  return loc === 'global' ? globalMcpPath() : localMcpPath();
+}
+
+function getCopilotServerEntry(): { type: string; command: string; args: string[]; tools: string[] } {
+  return {
+    type: 'local',
+    command: 'codegraph',
+    args: ['serve', '--mcp'],
+    tools: ['*'],
+  };
+}
+
+class CopilotCliTarget implements AgentTarget {
+  readonly id = 'copilot' as const;
+  readonly displayName = 'GitHub Copilot CLI';
+  readonly docsUrl = 'https://docs.github.com/en/copilot/how-tos/copilot-cli/customize-copilot/add-mcp-servers';
+
+  supportsLocation(_loc: Location): boolean {
+    return true;
+  }
+
+  detect(loc: Location): DetectionResult {
+    const file = mcpPath(loc);
+    const config = readJsonFile(file);
+    const alreadyConfigured = !!config.mcpServers?.codegraph;
+    const installed = loc === 'global'
+      ? fs.existsSync(globalConfigDir()) || fs.existsSync(file)
+      : fs.existsSync(file) || fs.existsSync(path.join(process.cwd(), '.github'));
+    return { installed, alreadyConfigured, configPath: file };
+  }
+
+  install(loc: Location, _opts: InstallOptions): WriteResult {
+    return {
+      files: [writeMcpEntry(loc)],
+    };
+  }
+
+  uninstall(loc: Location): WriteResult {
+    return { files: [removeMcpEntry(loc)] };
+  }
+
+  printConfig(loc: Location): string {
+    const target = mcpPath(loc);
+    const snippet = JSON.stringify({ mcpServers: { codegraph: getCopilotServerEntry() } }, null, 2);
+    return `# Add to ${target}\n\n${snippet}\n`;
+  }
+
+  describePaths(loc: Location): string[] {
+    return [mcpPath(loc)];
+  }
+}
+
+function writeMcpEntry(loc: Location): WriteResult['files'][number] {
+  const file = mcpPath(loc);
+  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 = getCopilotServerEntry();
+
+  if (jsonDeepEqual(before, after)) {
+    return { path: file, action: 'unchanged' };
+  }
+
+  const action: 'created' | 'updated' =
+    fs.existsSync(file) ? 'updated' : 'created';
+  if (!existing.mcpServers) existing.mcpServers = {};
+  existing.mcpServers.codegraph = after;
+  writeJsonFile(file, existing);
+  return { path: file, action };
+}
+
+function removeMcpEntry(loc: Location): WriteResult['files'][number] {
+  const file = mcpPath(loc);
+  const config = readJsonFile(file);
+  if (!config.mcpServers?.codegraph) {
+    return { path: file, action: 'not-found' };
+  }
+  delete config.mcpServers.codegraph;
+  if (Object.keys(config.mcpServers).length === 0) {
+    delete config.mcpServers;
+  }
+  writeJsonFile(file, config);
+  return { path: file, action: 'removed' };
+}
+
+export const copilotTarget: AgentTarget = new CopilotCliTarget();
diff --git a/src/installer/targets/registry.ts b/src/installer/targets/registry.ts
index 5e929d468..e12c3056c 100644
--- a/src/installer/targets/registry.ts
+++ b/src/installer/targets/registry.ts
@@ -16,6 +16,7 @@ import { hermesTarget } from './hermes';
 import { geminiTarget } from './gemini';
 import { antigravityTarget } from './antigravity';
 import { kiroTarget } from './kiro';
+import { copilotTarget } from './copilot';
 
 export const ALL_TARGETS: readonly AgentTarget[] = Object.freeze([
   claudeTarget,
@@ -26,6 +27,7 @@ export const ALL_TARGETS: readonly AgentTarget[] = Object.freeze([
   geminiTarget,
   antigravityTarget,
   kiroTarget,
+  copilotTarget,
 ]);
 
 export function getTarget(id: string): AgentTarget | undefined {
diff --git a/src/installer/targets/types.ts b/src/installer/targets/types.ts
index 833a801ae..8dd7d0ab2 100644
--- a/src/installer/targets/types.ts
+++ b/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' | 'gemini' | 'antigravity' | 'kiro';
+export type TargetId = 'claude' | 'cursor' | 'codex' | 'opencode' | 'hermes' | 'gemini' | 'antigravity' | 'kiro' | 'copilot';
 
 /**
  * Result of `target.detect(location)`.