perf(http): reduce maxSockets from 50 to 10 for CLI resource management (Issue #9)

Reduced HTTP/HTTPS agent maxSockets from 50 to 10 for better resource management.

Changes:
- Updated httpAgent.maxSockets: 50 → 10
- Updated httpsAgent.maxSockets: 50 → 10
- Added explanatory comments about conservative value for CLI tools
- Prevents resource exhaustion on user machines
- Still allows reasonable parallelism for batch operations

Impact:
- Lower memory footprint
- Reduced system resource usage
- Minimal performance impact (CLI rarely needs >10 concurrent connections)

Location: src/api/deepl-client.ts:133-147

Author: sjsyrek

CHANGELOG.md

@@ -52,6 +52,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - **Performance Benefit**: Avoids expensive database aggregation on every cache write
   - Location: `src/storage/cache.ts` (currentSize field, initialize, set, clear, cleanupExpired, evictIfNeeded)
 
+- **Performance Optimization: HTTP Connection Pool Size** - Reduced resource consumption for CLI tool (Issue #9)
+  - Reduced maxSockets from 50 to 10 for both HTTP and HTTPS agents
+  - Conservative value prevents resource exhaustion on user machines
+  - 50 concurrent sockets was excessive for a CLI tool's typical workload
+  - Still allows reasonable parallelism for batch operations
+  - Matches maxFreeSockets value for consistency
+  - **Impact**: Lower memory footprint and reduced system resource usage
+  - **Performance Trade-off**: Minimal impact on throughput; CLI rarely needs >10 concurrent connections
+  - Location: `src/api/deepl-client.ts:133-147` (HTTP/HTTPS agent configuration)
+
 ### Security
 - **Symlink Path Validation** - Prevents directory traversal attacks (Issue #6)
   - Rejects symlinks at translate() entry point before processing files

src/api/deepl-client.ts

@@ -130,17 +130,18 @@ export class DeepLClient {
         'Connection': 'keep-alive',
       },
       // Enable HTTP keep-alive for better performance in batch operations
+      // Issue #9: Reduced maxSockets from 50 to 10 for CLI tool resource management
       httpAgent: new http.Agent({
         keepAlive: true,
         keepAliveMsecs: 1000,
-        maxSockets: 50,
+        maxSockets: 10, // Conservative value for CLI tool to prevent resource exhaustion
         maxFreeSockets: 10,
         timeout: options.timeout ?? DEFAULT_TIMEOUT,
       }),
       httpsAgent: new https.Agent({
         keepAlive: true,
         keepAliveMsecs: 1000,
-        maxSockets: 50,
+        maxSockets: 10, // Conservative value for CLI tool to prevent resource exhaustion
         maxFreeSockets: 10,
         timeout: options.timeout ?? DEFAULT_TIMEOUT,
       }),