diff --git a/__tests__/installer-targets.test.ts b/__tests__/installer-targets.test.ts
index 27fcbd6e8..63ec3dbe5 100644
--- a/__tests__/installer-targets.test.ts
+++ b/__tests__/installer-targets.test.ts
@@ -1067,6 +1067,127 @@ describe('Installer targets — partial-state idempotency', () => {
     expect(fs.readFileSync(file, 'utf-8')).toBe(firstPass);
   });
 
+  it('copilot: global install writes ~/.copilot/mcp-config.json with type "local" + tools ["*"]', () => {
+    const copilot = getTarget('copilot')!;
+    const result = copilot.install('global', { autoAllow: true });
+    const mcp = path.join(tmpHome, '.copilot', 'mcp-config.json');
+    expect(result.files.some((f) => f.path === mcp)).toBe(true);
+
+    const cfg = JSON.parse(fs.readFileSync(mcp, 'utf-8'));
+    expect(cfg.mcpServers.codegraph).toEqual({
+      type: 'local',
+      command: 'codegraph',
+      args: ['serve', '--mcp'],
+      tools: ['*'],
+    });
+  });
+
+  it('copilot: local install writes ./.mcp.json with type "stdio" (no tools field)', () => {
+    const copilot = getTarget('copilot')!;
+    const result = copilot.install('local', { autoAllow: true });
+    const paths = result.files.map((f) => f.path.replace(/\\/g, '/'));
+    // macOS realpath: use suffix match like the kiro local test.
+    expect(paths.some((p) => p.endsWith('/.mcp.json'))).toBe(true);
+
+    const mcpFile = path.join(tmpCwd, '.mcp.json');
+    const cfg = JSON.parse(fs.readFileSync(mcpFile, 'utf-8'));
+    expect(cfg.mcpServers.codegraph).toEqual({
+      type: 'stdio',
+      command: 'codegraph',
+      args: ['serve', '--mcp'],
+    });
+    // No `tools` field in local config — it's shared with Claude Code.
+    expect(cfg.mcpServers.codegraph.tools).toBeUndefined();
+  });
+
+  it('copilot: global install creates ~/.copilot/ directory if missing', () => {
+    const copilot = getTarget('copilot')!;
+    const copilotDir = path.join(tmpHome, '.copilot');
+    expect(fs.existsSync(copilotDir)).toBe(false);
+
+    copilot.install('global', { autoAllow: true });
+
+    expect(fs.existsSync(copilotDir)).toBe(true);
+    expect(fs.existsSync(path.join(copilotDir, 'mcp-config.json'))).toBe(true);
+  });
+
+  it('copilot: install preserves a pre-existing sibling MCP server in mcp-config.json', () => {
+    const copilot = getTarget('copilot')!;
+    const mcp = path.join(tmpHome, '.copilot', 'mcp-config.json');
+    fs.mkdirSync(path.dirname(mcp), { recursive: true });
+    fs.writeFileSync(mcp, JSON.stringify({
+      mcpServers: { 'other-server': { type: 'local', command: 'other', args: [] } },
+    }, null, 2) + '\n');
+
+    copilot.install('global', { autoAllow: true });
+
+    const after = JSON.parse(fs.readFileSync(mcp, 'utf-8'));
+    expect(after.mcpServers['other-server']).toBeDefined();
+    expect(after.mcpServers.codegraph).toBeDefined();
+  });
+
+  it('copilot: uninstall strips codegraph but leaves sibling MCP servers intact', () => {
+    const copilot = getTarget('copilot')!;
+    const mcp = path.join(tmpHome, '.copilot', 'mcp-config.json');
+    fs.mkdirSync(path.dirname(mcp), { recursive: true });
+    fs.writeFileSync(mcp, JSON.stringify({
+      mcpServers: { 'other-server': { type: 'local', command: 'other', args: [] } },
+    }, null, 2) + '\n');
+
+    copilot.install('global', { autoAllow: true });
+    copilot.uninstall('global');
+
+    const after = JSON.parse(fs.readFileSync(mcp, 'utf-8'));
+    expect(after.mcpServers['other-server']).toBeDefined();
+    expect(after.mcpServers.codegraph).toBeUndefined();
+  });
+
+  it('copilot: re-running global install is idempotent', () => {
+    const copilot = getTarget('copilot')!;
+    copilot.install('global', { autoAllow: true });
+    const first = fs.readFileSync(path.join(tmpHome, '.copilot', 'mcp-config.json'), 'utf-8');
+
+    const second = copilot.install('global', { autoAllow: true });
+    for (const f of second.files) {
+      expect(f.action).toBe('unchanged');
+    }
+    expect(fs.readFileSync(path.join(tmpHome, '.copilot', 'mcp-config.json'), 'utf-8')).toBe(first);
+  });
+
+  it('copilot: re-running local install is idempotent', () => {
+    const copilot = getTarget('copilot')!;
+    copilot.install('local', { autoAllow: true });
+    const first = fs.readFileSync(path.join(tmpCwd, '.mcp.json'), 'utf-8');
+
+    const second = copilot.install('local', { autoAllow: true });
+    for (const f of second.files) {
+      expect(f.action).toBe('unchanged');
+    }
+    expect(fs.readFileSync(path.join(tmpCwd, '.mcp.json'), 'utf-8')).toBe(first);
+  });
+
+  it('copilot: uninstall on a clean slate reports not-found', () => {
+    const copilot = getTarget('copilot')!;
+    const result = copilot.uninstall('global');
+    expect(result.files[0].action).toBe('not-found');
+  });
+
+  it('copilot: printConfig outputs valid JSON with the correct entry shape', () => {
+    const copilot = getTarget('copilot')!;
+    const globalOut = copilot.printConfig('global');
+    // printConfig uses os.homedir() → absolute path in tests; just check suffix.
+    expect(globalOut).toContain('.copilot/mcp-config.json');
+    const globalJson = JSON.parse(globalOut.split('\n').filter((l) => !l.startsWith('#')).join('\n').trim());
+    expect(globalJson.mcpServers.codegraph.type).toBe('local');
+    expect(globalJson.mcpServers.codegraph.tools).toEqual(['*']);
+
+    const localOut = copilot.printConfig('local');
+    expect(localOut).toContain('.mcp.json');
+    const localJson = JSON.parse(localOut.split('\n').filter((l) => !l.startsWith('#')).join('\n').trim());
+    expect(localJson.mcpServers.codegraph.type).toBe('stdio');
+    expect(localJson.mcpServers.codegraph.tools).toBeUndefined();
+  });
+
   it('claude: uninstall strips stale hooks written in the npx form (local)', () => {
     const claude = getTarget('claude')!;
     const file = seedSettings('local', {
@@ -1098,6 +1219,7 @@ describe('Installer targets — registry', () => {
     expect(getTarget('gemini')?.id).toBe('gemini');
     expect(getTarget('antigravity')?.id).toBe('antigravity');
     expect(getTarget('kiro')?.id).toBe('kiro');
+    expect(getTarget('copilot')?.id).toBe('copilot');
     expect(getTarget('not-a-real-target')).toBeUndefined();
   });
 
diff --git a/src/installer/index.ts b/src/installer/index.ts
index edd48ecaf..101997c35 100644
--- a/src/installer/index.ts
+++ b/src/installer/index.ts
@@ -146,8 +146,8 @@ export async function runInstallerWithOptions(opts: RunInstallerOptions): Promis
       const sel = await clack.select({
         message: 'Apply agent configs to all your projects, or just this one?',
         options: [
-          { value: 'global' as const, label: 'All projects', hint: '~/.claude, ~/.cursor, etc.' },
-          { value: 'local'  as const, label: 'Just this project', hint: './.claude, ./.cursor, etc.' },
+          { value: 'global' as const, label: 'All projects', hint: '~/.claude, ~/.cursor, ~/.copilot, etc.' },
+          { value: 'local'  as const, label: 'Just this project', hint: './.claude, ./.cursor, ./.mcp.json, etc.' },
         ],
         initialValue: 'global' as const,
       });
diff --git a/src/installer/targets/copilot.ts b/src/installer/targets/copilot.ts
new file mode 100644
index 000000000..7ceadb3b4
--- /dev/null
+++ b/src/installer/targets/copilot.ts
@@ -0,0 +1,159 @@
+/**
+ * GitHub Copilot CLI target. Writes:
+ *
+ *   - MCP server entry to `~/.copilot/mcp-config.json` (global) or
+ *     `./.mcp.json` (local, shared with Claude Code). Copilot CLI
+ *     auto-loads both paths and merges them.
+ *
+ * No permissions concept — Copilot CLI does not gate tool invocations
+ * behind an external allowlist. `autoAllow` is silently ignored.
+ * No instructions/steering file — the MCP server's `initialize`
+ * response is the single source of truth for agent guidance.
+ *
+ * The config entry shape differs by location:
+ *   - Global: `{ type: "local", command, args, tools: ["*"] }`
+ *     Copilot CLI convention: `"local"` is its native name for stdio
+ *     servers (though `"stdio"` also works). `tools: ["*"]` ensures
+ *     compatibility with Copilot CLI versions before v0.0.404, which
+ *     required this field.
+ *   - Local: `{ type: "stdio", command, args }`
+ *     Uses the standard MCP shape because `./.mcp.json` is shared
+ *     with Claude Code, which expects `"stdio"`. Copilot CLI accepts
+ *     `"stdio"` as an alias for `"local"`, so the entry works for
+ *     both agents.
+ *
+ * Docs: https://docs.github.com/en/copilot/customizing-copilot/extending-copilot-chat-with-mcp
+ */
+
+import * as fs from 'fs';
+import * as path from 'path';
+import * as os from 'os';
+import {
+  AgentTarget,
+  DetectionResult,
+  InstallOptions,
+  Location,
+  WriteResult,
+} from './types';
+import {
+  getMcpServerConfig,
+  jsonDeepEqual,
+  readJsonFile,
+  writeJsonFile,
+} from './shared';
+
+function mcpConfigPath(loc: Location): string {
+  return loc === 'global'
+    ? path.join(os.homedir(), '.copilot', 'mcp-config.json')
+    : path.join(process.cwd(), '.mcp.json');
+}
+
+/**
+ * Build the codegraph MCP entry in Copilot CLI's preferred shape.
+ *
+ * Global: `{ type: "local", command, args, tools: ["*"] }`
+ *   - `"local"` is Copilot CLI's native name for stdio transports
+ *   - `tools: ["*"]` ensures pre-v0.0.404 compatibility
+ *
+ * Local: `{ type: "stdio", command, args }`
+ *   - Standard MCP shape for the shared `.mcp.json` file
+ *   - Copilot CLI accepts `"stdio"` as an alias for `"local"`
+ */
+function buildCopilotMcpConfig(loc: Location): Record<string, unknown> {
+  if (loc === 'global') {
+    return {
+      type: 'local',
+      command: 'codegraph',
+      args: ['serve', '--mcp'],
+      tools: ['*'],
+    };
+  }
+  // Local: reuse the standard MCP shape for cross-agent compatibility
+  // with Claude Code, which also reads `./.mcp.json`.
+  return getMcpServerConfig() as Record<string, unknown>;
+}
+
+class CopilotTarget implements AgentTarget {
+  readonly id = 'copilot' as const;
+  readonly displayName = 'GitHub Copilot CLI';
+  readonly docsUrl = 'https://docs.github.com/en/copilot/customizing-copilot/extending-copilot-chat-with-mcp';
+
+  supportsLocation(_loc: Location): boolean {
+    return true;
+  }
+
+  detect(loc: Location): DetectionResult {
+    const file = mcpConfigPath(loc);
+    const config = readJsonFile(file);
+    const alreadyConfigured = !!config.mcpServers?.codegraph;
+    const installed = loc === 'global'
+      ? fs.existsSync(path.join(os.homedir(), '.copilot')) || fs.existsSync(file)
+      : fs.existsSync(file);
+    return { installed, alreadyConfigured, configPath: file };
+  }
+
+  install(loc: Location, _opts: InstallOptions): WriteResult {
+    const files: WriteResult['files'] = [];
+    files.push(writeMcpEntry(loc));
+
+    return {
+      files,
+      notes: ['Restart Copilot CLI for MCP changes to take effect.'],
+    };
+  }
+
+  uninstall(loc: Location): WriteResult {
+    const files: WriteResult['files'] = [];
+
+    const file = mcpConfigPath(loc);
+    const config = readJsonFile(file);
+    if (config.mcpServers?.codegraph) {
+      delete config.mcpServers.codegraph;
+      if (Object.keys(config.mcpServers).length === 0) {
+        delete config.mcpServers;
+      }
+      writeJsonFile(file, config);
+      files.push({ path: file, action: 'removed' });
+    } else {
+      files.push({ path: file, action: 'not-found' });
+    }
+
+    return { files };
+  }
+
+  printConfig(loc: Location): string {
+    const target = mcpConfigPath(loc);
+    const snippet = JSON.stringify(
+      { mcpServers: { codegraph: buildCopilotMcpConfig(loc) } },
+      null,
+      2,
+    );
+    return `# Add to ${target}\n\n${snippet}\n`;
+  }
+
+  describePaths(loc: Location): string[] {
+    return [mcpConfigPath(loc)];
+  }
+}
+
+function writeMcpEntry(loc: Location): WriteResult['files'][number] {
+  const file = mcpConfigPath(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 = buildCopilotMcpConfig(loc);
+
+  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 };
+}
+
+export const copilotTarget: AgentTarget = new CopilotTarget();
\ No newline at end of file
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 4b3267e97..ce3c7a2c5 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)`.