Use type imports for type-only imports

Add `type` modifier to imports that are only used for type checking.
This improves tree-shaking and makes it clear which imports are
only used at compile time. Also update CLAUDE.md with this convention.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: vdiez

CLAUDE.md

@@ -81,6 +81,18 @@ logWithPrefix(LogLevel.INFO, 'ComponentName', 'message');
 
 Prettier config: 100 char width, trailing commas, single quotes, LF line endings. Pre-commit hook auto-formats staged files.
 
+### Pre-commit Checks
+
+Before committing, verify there are no TypeScript errors and no unused exports:
+
+```bash
+npx tsc --noEmit -p tsconfig.json
+npx tsc --noEmit -p test/unit/tsconfig.json
+npx knip
+```
+
+Note: `test/integration/tsconfig.json` requires running `npm install` in `test/integration/` first, as it depends on the build artifact.
+
 ### External Tools
 
 - Use `gh` CLI to interact with GitHub (issues, PRs, etc.)
@@ -101,6 +113,23 @@ import path from 'path';
 import { spawn } from 'child_process';
 ```
 
+### Type Imports
+
+Use `import type` when importing types only. This helps with tree-shaking and makes it clear which imports are only used for type checking:
+
+```typescript
+// When all imports are types, use import type
+import type { ScannerProperties, ScanOptions } from './types';
+import type { ChildProcess, SpawnOptions } from 'node:child_process';
+
+// When mixing types and values, use inline type modifier
+import { type ChildProcess, spawn } from 'node:child_process';
+import { type ScannerProperties, ScannerProperty } from './types';
+
+// Incorrect: importing types as regular imports
+import { ScannerProperties, ScanOptions } from './types';
+```
+
 ## Testing
 
 ### Unit Tests

src/file.ts

@@ -25,7 +25,7 @@ import tarStream from 'tar-stream';
 import zlib from 'node:zlib';
 import { SONAR_CACHE_DIR, UNARCHIVE_SUFFIX } from './constants';
 import { LogLevel, log } from './logging';
-import { CacheFileData, ScannerProperties, ScannerProperty } from './types';
+import { type CacheFileData, type ScannerProperties, ScannerProperty } from './types';
 
 export interface FileDeps {
   existsSync: typeof fs.existsSync;

src/index.ts

@@ -18,7 +18,7 @@
  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 import { scan } from './scan';
-import { ScanOptions } from './types';
+import type { ScanOptions } from './types';
 
 export { scan };
 

src/java.ts

@@ -19,7 +19,7 @@
  */
 import fs from 'node:fs';
 import path from 'node:path';
-import semver, { SemVer } from 'semver';
+import semver, { type SemVer } from 'semver';
 import {
   API_OLD_VERSION_ENDPOINT,
   API_V2_JRE_ENDPOINT,
@@ -37,10 +37,10 @@ import {
 import { LogLevel, log } from './logging';
 import { download, fetch } from './request';
 import {
-  AnalysisJreMetaData,
-  AnalysisJresResponseType,
+  type AnalysisJreMetaData,
+  type AnalysisJresResponseType,
   CacheStatus,
-  ScannerProperties,
+  type ScannerProperties,
   ScannerProperty,
 } from './types';
 

src/process.ts

@@ -40,9 +40,11 @@ const defaultProcessDeps: ProcessProcessDeps = {
   },
 };
 
+type ExecAsyncFn = (command: string) => Promise<{ stdout: string; stderr: string }>;
+
 export interface ProcessModuleDeps {
   processDeps?: ProcessProcessDeps;
-  execAsyncFn?: typeof execAsync;
+  execAsyncFn?: ExecAsyncFn;
 }
 
 /**

src/properties.ts

@@ -45,10 +45,10 @@ import { getArch, getSupportedOS } from './platform';
 import { version } from './version';
 import {
   CacheStatus,
-  CliArgs,
-  PackageJson,
-  ScanOptions,
-  ScannerProperties,
+  type CliArgs,
+  type PackageJson,
+  type ScanOptions,
+  type ScannerProperties,
   ScannerProperty,
 } from './types';
 

src/proxy.ts

@@ -19,7 +19,7 @@
  */
 import { URL } from 'node:url';
 import { LogLevel, log } from './logging';
-import { ScannerProperties, ScannerProperty } from './types';
+import { type ScannerProperties, ScannerProperty } from './types';
 
 export function getProxyUrl(properties: ScannerProperties): URL | undefined {
   const proxyHost = properties[ScannerProperty.SonarScannerProxyHost];

src/request.ts

@@ -17,7 +17,7 @@
  * along with this program; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-import axios, { AxiosInstance, AxiosRequestConfig } from 'axios';
+import axios, { type AxiosInstance, type AxiosRequestConfig } from 'axios';
 import fs from 'node:fs';
 import { HttpProxyAgent, HttpsProxyAgent } from 'hpagent';
 import https from 'node:https';
@@ -26,7 +26,7 @@ import * as stream from 'node:stream';
 import { promisify } from 'node:util';
 import { LogLevel, log } from './logging';
 import { getProxyUrl } from './proxy';
-import { ScannerProperties, ScannerProperty } from './types';
+import { type ScannerProperties, ScannerProperty } from './types';
 
 const finished = promisify(stream.finished);
 

src/scan.ts

@@ -34,7 +34,7 @@ import {
   fetchScannerEngine as defaultFetchScannerEngine,
   runScannerEngine as defaultRunScannerEngine,
 } from './scanner-engine';
-import { CliArgs, ScanOptions, ScannerProperty } from './types';
+import { type CliArgs, type ScanOptions, ScannerProperty } from './types';
 import { version } from './version';
 
 export interface ScanDeps {

src/scanner-cli.ts

@@ -17,7 +17,7 @@
  * along with this program; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-import { AxiosRequestConfig } from 'axios';
+import type { AxiosRequestConfig } from 'axios';
 import { spawn as nodeSpawn } from 'node:child_process';
 import fs from 'node:fs';
 import path from 'node:path';
@@ -34,7 +34,7 @@ import { LogLevel, log } from './logging';
 import { isLinux, isMac, isWindows } from './platform';
 import { proxyUrlToJavaOptions } from './proxy';
 import { download } from './request';
-import { ScanOptions, ScannerProperties, ScannerProperty } from './types';
+import { type ScanOptions, type ScannerProperties, ScannerProperty } from './types';
 
 export interface ScannerCliFsDeps {
   exists: (path: string) => Promise<boolean>;
@@ -47,7 +47,7 @@ export interface ScannerCliProcessDeps {
   env: NodeJS.ProcessEnv;
 }
 
-export type SpawnFn = typeof nodeSpawn;
+type SpawnFn = typeof nodeSpawn;
 
 const defaultFsDeps: ScannerCliFsDeps = {
   exists: async (filePath: string) => {