diff --git a/src/installer/targets/devin.ts b/src/installer/targets/devin.ts
new file mode 100644
index 00000000..0a815d2a
--- /dev/null
+++ b/src/installer/targets/devin.ts
@@ -0,0 +1,156 @@
+/**
+ * Devin for Terminal target.
+ *
+ *   - User config: `~/.config/devin/config.json` (POSIX) or
+ *     `%APPDATA%/devin/config.json` (Windows).
+ *   - Project config: `./.devin/config.json`.
+ *   - MCP config goes under `mcpServers.codegraph` with the stdio
+ *     block `{ command: 'codegraph', args: ['serve', '--mcp'] }`.
+ *   - Devin reads `AGENTS.md`, so global writes `~/.config/devin/AGENTS.md`
+ *     and local writes `./AGENTS.md`.
+ *   - No permissions concept.
+ */
+
+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,
+  removeMarkedSection,
+  replaceOrAppendMarkedSection,
+  writeJsonFile,
+} from './shared';
+import {
+  CODEGRAPH_SECTION_END,
+  CODEGRAPH_SECTION_START,
+  INSTRUCTIONS_TEMPLATE,
+} from '../instructions-template';
+
+function globalConfigDir(): string {
+  if (process.platform === 'win32') {
+    const appData = process.env.APPDATA ?? path.join(os.homedir(), 'AppData', 'Roaming');
+    return path.join(appData, 'devin');
+  }
+  return path.join(os.homedir(), '.config', 'devin');
+}
+
+function configPath(loc: Location): string {
+  return path.join(loc === 'global' ? globalConfigDir() : path.join(process.cwd(), '.devin'), 'config.json');
+}
+
+function instructionsPath(loc: Location): string {
+  return path.join(loc === 'global' ? globalConfigDir() : process.cwd(), 'AGENTS.md');
+}
+
+function readConfig(file: string): Record<string, any> {
+  if (!fs.existsSync(file)) return {};
+  try {
+    const text = fs.readFileSync(file, 'utf-8');
+    const parsed = JSON.parse(text);
+    return parsed && typeof parsed === 'object' && !Array.isArray(parsed) ? parsed : {};
+  } catch {
+    return {};
+  }
+}
+
+class DevinTarget implements AgentTarget {
+  readonly id = 'devin' as const;
+  readonly displayName = 'Devin for Terminal';
+
+  supportsLocation(_loc: Location): boolean {
+    return true;
+  }
+
+  detect(loc: Location): DetectionResult {
+    const file = configPath(loc);
+    const config = readConfig(file);
+    const alreadyConfigured = !!config.mcpServers?.codegraph;
+    const installed = loc === 'global'
+      ? fs.existsSync(globalConfigDir())
+      : fs.existsSync(path.join(process.cwd(), '.devin'));
+    return { installed, alreadyConfigured, configPath: file };
+  }
+
+  install(loc: Location, _opts: InstallOptions): WriteResult {
+    return {
+      files: [writeMcpEntry(loc), writeInstructionsEntry(loc)],
+    };
+  }
+
+  uninstall(loc: Location): WriteResult {
+    const files: WriteResult['files'] = [];
+    const file = configPath(loc);
+    if (!fs.existsSync(file)) {
+      files.push({ path: file, action: 'not-found' });
+    } else {
+      const config = readConfig(file);
+      if (!config.mcpServers?.codegraph) {
+        files.push({ path: file, action: 'not-found' });
+      } else {
+        delete config.mcpServers.codegraph;
+        if (Object.keys(config.mcpServers).length === 0) {
+          delete config.mcpServers;
+        }
+        writeJsonFile(file, config);
+        files.push({ path: file, action: 'removed' });
+      }
+    }
+
+    files.push({
+      path: instructionsPath(loc),
+      action: removeMarkedSection(instructionsPath(loc), CODEGRAPH_SECTION_START, CODEGRAPH_SECTION_END),
+    });
+    return { files };
+  }
+
+  printConfig(loc: Location): string {
+    return `# Add to ${configPath(loc)}\n\n${JSON.stringify({
+      mcpServers: { codegraph: getMcpServerConfig() },
+    }, null, 2)}\n`;
+  }
+
+  describePaths(loc: Location): string[] {
+    return [configPath(loc), instructionsPath(loc)];
+  }
+}
+
+function writeMcpEntry(loc: Location): WriteResult['files'][number] {
+  const file = configPath(loc);
+  const existed = fs.existsSync(file);
+  const config = readConfig(file);
+  const before = config.mcpServers?.codegraph;
+  const after = getMcpServerConfig();
+
+  if (jsonDeepEqual(before, after)) {
+    return { path: file, action: 'unchanged' };
+  }
+
+  if (!config.mcpServers) config.mcpServers = {};
+  config.mcpServers.codegraph = after;
+  writeJsonFile(file, config);
+  return { path: file, action: existed ? 'updated' : 'created' };
+}
+
+function writeInstructionsEntry(loc: Location): WriteResult['files'][number] {
+  const file = instructionsPath(loc);
+  const action = replaceOrAppendMarkedSection(
+    file,
+    INSTRUCTIONS_TEMPLATE,
+    CODEGRAPH_SECTION_START,
+    CODEGRAPH_SECTION_END,
+  );
+  return {
+    path: file,
+    action: action === 'created' ? 'created' : action === 'unchanged' ? 'unchanged' : 'updated',
+  };
+}
+
+export const devinTarget: AgentTarget = new DevinTarget();
diff --git a/src/installer/targets/registry.ts b/src/installer/targets/registry.ts
index 0091ab64..ff1fd8cd 100644
--- a/src/installer/targets/registry.ts
+++ b/src/installer/targets/registry.ts
@@ -11,6 +11,7 @@ import { AgentTarget, Location, TargetId } from './types';
 import { claudeTarget } from './claude';
 import { cursorTarget } from './cursor';
 import { codexTarget } from './codex';
+import { devinTarget } from './devin';
 import { opencodeTarget } from './opencode';
 import { hermesTarget } from './hermes';
 
@@ -18,6 +19,7 @@ export const ALL_TARGETS: readonly AgentTarget[] = Object.freeze([
   claudeTarget,
   cursorTarget,
   codexTarget,
+  devinTarget,
   opencodeTarget,
   hermesTarget,
 ]);
diff --git a/src/installer/targets/types.ts b/src/installer/targets/types.ts
index 290f13ce..fbc9eb53 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';
+export type TargetId = 'claude' | 'cursor' | 'codex' | 'devin' | 'opencode' | 'hermes';
 
 /**
  * Result of `target.detect(location)`.