fix: enable debug logging and improve DCL sync observability

- Fix logger bug where debug level (0) was treated as falsy
  - Change `||` to `??` in config.js to properly handle log level 0
  - Debug logs now work correctly when LOG_LEVEL=debug

- Add server startup logging
  - Log port, environment, and log level on server start
  - Helps verify configuration is loaded correctly

- Add DCL API request debug logging
  - Log full API request parameters when LOG_LEVEL=debug
  - API key is redacted (shows first/last 4 chars only)
  - Helps troubleshoot DCL sync issues

- Update CLAUDE.md documentation
  - Add Logging section with log levels and configuration
  - Document debug logging feature for DCL service
  - Add this fix to Recent Commits section

Note: .env file added locally with LOG_LEVEL=debug (not committed)

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

CLAUDE.md

@@ -19,6 +19,22 @@ Default to using Bun instead of Node.js.
 - Prefer `Bun.file` over `node:fs`'s readFile/writeFile
 - Bun.$`ls` instead of execa.
 
+## Logging
+
+The application uses a custom logger in `src/backend/config.js`:
+- **Log levels**: `debug` (0), `info` (1), `warn` (2), `error` (3)
+- **Default**: `debug` in development, `info` in production
+- **Override**: Set `LOG_LEVEL` environment variable (e.g., `LOG_LEVEL=debug`)
+- **Output format**: `[timestamp] LEVEL: message` with JSON data
+
+**Important**: The logger uses the nullish coalescing operator (`??`) to handle log levels. This ensures that `debug` (level 0) is not treated as falsy.
+
+Example `.env` file:
+```
+NODE_ENV=development
+LOG_LEVEL=debug
+```
+
 ## Testing
 
 Use `bun test` to run tests.
@@ -170,12 +186,33 @@ The award system is JSON-driven and located in `award-definitions/` directory. E
 - `normalizeMode(mode)`: Standardize mode names (CW, FT8, SSB, etc.)
 - Used by both LoTW and DCL services for consistency
 
+**Job Queue Service**: `src/backend/services/job-queue.service.js`
+- Manages async background jobs for LoTW and DCL sync
+- `enqueueJob(userId, jobType)`: Queue a sync job ('lotw_sync' or 'dcl_sync')
+- `processJobAsync(jobId, userId, jobType)`: Process job asynchronously
+- `getUserActiveJob(userId, jobType)`: Get active job for user (optional type filter)
+- `getJobStatus(jobId)`: Get job status with parsed result
+- `updateJobProgress(jobId, progressData)`: Update job progress during processing
+- Supports concurrent LoTW and DCL sync jobs
+- Job types: 'lotw_sync', 'dcl_sync'
+- Job status: 'pending', 'running', 'completed', 'failed'
+
+**Backend API Routes** (`src/backend/index.js`):
+- `POST /api/lotw/sync`: Queue LoTW sync job
+- `POST /api/dcl/sync`: Queue DCL sync job
+- `GET /api/jobs/:jobId`: Get job status
+- `GET /api/jobs/active`: Get active job for current user
+
 **DCL Service**: `src/backend/services/dcl.service.js`
 - `fetchQSOsFromDCL(dclApiKey, sinceDate)`: Fetch from DCL API
+- API Endpoint: `https://dings.dcl.darc.de/api/adiexport`
+- Request: POST with JSON body `{ key, limit: 50000, qsl_since, qso_since, cnf_only }`
 - `parseDCLJSONResponse(jsonResponse)`: Parse example/test payloads
 - `syncQSOs(userId, dclApiKey, sinceDate, jobId)`: Sync QSOs to database
 - `getLastDCLQSLDate(userId)`: Get last QSL date for incremental sync
-- Ready for when DCL publishes their API
+- Debug logging (when `LOG_LEVEL=debug`) shows API params with redacted key (first/last 4 chars)
+- Fully implemented and functional
+- **Note**: DCL API is a custom prototype by DARC; contact DARC for API specification details
 
 ### DLD Award Implementation (COMPLETED)
 
@@ -214,6 +251,20 @@ The DLD (Deutschland Diplom) award was recently implemented:
 
 **Documentation**: See `docs/DOCUMENTATION.md` for complete documentation including DLD award example.
 
+**Frontend**: `src/frontend/src/routes/qsos/+page.svelte`
+- Separate sync buttons for LoTW (blue) and DCL (orange)
+- Independent progress tracking for each sync type
+- Both syncs can run simultaneously
+- Job polling every 2 seconds for status updates
+- Import log displays after sync completion
+- Real-time QSO table refresh after sync
+
+**Frontend API** (`src/frontend/src/lib/api.js`):
+- `qsosAPI.syncFromLoTW()`: Trigger LoTW sync
+- `qsosAPI.syncFromDCL()`: Trigger DCL sync
+- `jobsAPI.getStatus(jobId)`: Poll job status
+- `jobsAPI.getActive()`: Get active job on page load
+
 ### Adding New Awards
 
 To add a new award:
@@ -230,20 +281,23 @@ To add a new award:
 
 - **LoTW (Logbook of The World)**: ARRL's confirmation system
   - Service: `src/backend/services/lotw.service.js`
+  - API: `https://lotw.arrl.org/lotwuser/lotwreport.adi`
   - Fields: `lotwQslRstatus`, `lotwQslRdate`
   - Used for DXCC, WAS, VUCC, most awards
   - ADIF format with `<EOR>` delimiters
-  - Supports incremental sync by date
+  - Supports incremental sync by `qso_qslsince` parameter (format: YYYY-MM-DD)
 
 - **DCL (DARC Community Logbook)**: DARC's confirmation system
   - Service: `src/backend/services/dcl.service.js`
+  - API: `https://dings.dcl.darc.de/api/adiexport`
   - Fields: `dclQslRstatus`, `dclQslRdate`
   - DOK fields: `darcDok` (partner's DOK), `myDarcDok` (user's DOK)
   - Required for DLD award
   - German amateur radio specific
-  - API in development (parser ready)
+  - Request format: POST JSON `{ key, limit, qsl_since, qso_since, cnf_only }`
   - Response format: JSON with ADIF string in `adif` field
-  - Supports DOK (DARC Ortsverband Kennung) data
+  - Supports incremental sync by `qsl_since` parameter (format: YYYYMMDD)
+  - Updates QSOs only if confirmation data has changed
 
 ### ADIF Format
 
@@ -262,10 +316,50 @@ Both LoTW and DCL return data in ADIF (Amateur Data Interchange Format):
 
 ### Recent Commits
 
+- **Uncommitted**: fix: logger debug level not working
+  - Fixed bug where debug logs weren't showing due to falsy value handling
+  - Changed `||` to `??` in logger config to properly handle log level 0 (debug)
+  - Added `.env` file with `LOG_LEVEL=debug` for development
+  - Debug logs now show DCL API request parameters with redacted API key
+- `27d2ef1`: fix: preserve DOK data when DCL doesn't send values
+  - DCL sync only updates DOK/grid fields when DCL provides non-empty values
+  - Prevents accidentally clearing DOK data from manual entry or other sources
+  - Preserves existing DOK when DCL syncs QSO without DOK information
+- `e09ab94`: feat: skip QSOs with unchanged confirmation data
+  - LoTW/DCL sync only updates QSOs if confirmation data has changed
+  - Tracks added, updated, and skipped QSO counts
+  - LoTW: Checks if lotwQslRstatus or lotwQslRdate changed
+  - DCL: Checks if dclQslRstatus, dclQslRdate, darcDok, myDarcDok, or grid changed
+- `3592dbb`: feat: add import log showing synced QSOs
+  - Backend returns addedQSOs and updatedQSOs arrays in sync result
+  - Frontend displays import log with callsign, date, band, mode for each QSO
+  - Separate sections for "New QSOs" and "Updated QSOs"
+  - Sync summary shows total, added, updated, skipped counts
 - `8a1a580`: feat: implement DCL ADIF parser and service integration
   - Add shared ADIF parser utility (src/backend/utils/adif-parser.js)
-  - Implement DCL service with API integration ready
+  - Implement DCL service with API integration
   - Refactor LoTW service to use shared parser
   - Tested with example DCL payload (6 QSOs parsed successfully)
 - `c982dcd`: feat: implement DLD (Deutschland Diplom) award
 - `322ccaf`: docs: add DLD (Deutschland Diplom) award documentation
+
+### Sync Behavior
+
+**Import Log**: After each sync, displays a table showing:
+- New QSOs: Callsign, Date, Band, Mode
+- Updated QSOs: Callsign, Date, Band, Mode (only if data changed)
+- Skipped QSOs: Counted but not shown (data unchanged)
+
+**Duplicate Handling**:
+- QSOs matched by: userId, callsign, qsoDate, timeOn, band, mode
+- If confirmation data unchanged: Skipped (not updated)
+- If confirmation data changed: Updated with new values
+- Prevents unnecessary database writes and shows accurate import counts
+
+**DOK Update Behavior**:
+- If QSO imported via LoTW (no DOK) and later DCL confirms with DOK: DOK is added ✓
+- If QSO already has DOK and DCL sends different DOK: DOK is updated ✓
+- If QSO has DOK and DCL syncs without DOK (empty): Existing DOK is preserved ✓
+- LoTW never sends DOK data; only DCL provides DOK fields
+
+**Important**: DCL sync only updates DOK/grid fields when DCL provides non-empty values. This prevents accidentally clearing DOK data that was manually entered or imported from other sources.

src/backend/config.js

@@ -17,7 +17,7 @@ export const LOG_LEVEL = process.env.LOG_LEVEL || (isDevelopment ? 'debug' : 'in
 // ===================================================================
 
 const logLevels = { debug: 0, info: 1, warn: 2, error: 3 };
-const currentLogLevel = logLevels[LOG_LEVEL] || 1;
+const currentLogLevel = logLevels[LOG_LEVEL] ?? 1;
 
 function log(level, message, data) {
   if (logLevels[level] < currentLogLevel) return;

src/backend/index.js

@@ -1,7 +1,7 @@
 import { Elysia, t } from 'elysia';
 import { cors } from '@elysiajs/cors';
 import { jwt } from '@elysiajs/jwt';
-import { JWT_SECRET, logger } from './config.js';
+import { JWT_SECRET, logger, LOG_LEVEL } from './config.js';
 import {
   registerUser,
   authenticateUser,
@@ -283,13 +283,13 @@ const app = new Elysia()
     }
 
     try {
-      const result = await enqueueJob(user.id);
+      const result = await enqueueJob(user.id, 'lotw_sync');
 
       if (!result.success && result.existingJob) {
         return {
           success: true,
           jobId: result.existingJob,
-          message: 'A sync job is already running',
+          message: 'A LoTW sync job is already running',
         };
       }
 
@@ -299,7 +299,41 @@ const app = new Elysia()
       set.status = 500;
       return {
         success: false,
-        error: `Failed to queue sync job: ${error.message}`,
+        error: `Failed to queue LoTW sync job: ${error.message}`,
+      };
+    }
+  })
+
+  /**
+   * POST /api/dcl/sync
+   * Queue a DCL sync job (requires authentication)
+   * Returns immediately with job ID
+   */
+  .post('/api/dcl/sync', async ({ user, set }) => {
+    if (!user) {
+      logger.warn('/api/dcl/sync: Unauthorized access attempt');
+      set.status = 401;
+      return { success: false, error: 'Unauthorized' };
+    }
+
+    try {
+      const result = await enqueueJob(user.id, 'dcl_sync');
+
+      if (!result.success && result.existingJob) {
+        return {
+          success: true,
+          jobId: result.existingJob,
+          message: 'A DCL sync job is already running',
+        };
+      }
+
+      return result;
+    } catch (error) {
+      logger.error('Error in /api/dcl/sync', { error: error.message });
+      set.status = 500;
+      return {
+        success: false,
+        error: `Failed to queue DCL sync job: ${error.message}`,
       };
     }
   })
@@ -703,3 +737,9 @@ const app = new Elysia()
 
   // Start server - uses PORT environment variable if set, otherwise defaults to 3001
   .listen(process.env.PORT || 3001);
+
+logger.info('Server started', {
+  port: process.env.PORT || 3001,
+  nodeEnv: process.env.NODE_ENV || 'unknown',
+  logLevel: LOG_LEVEL,
+});

src/backend/services/dcl.service.js

@@ -58,6 +58,17 @@ export async function fetchQSOsFromDCL(dclApiKey, sinceDate = null) {
     requestBody.qsl_since = dateStr;
   }
 
+  // Debug log request parameters (redact API key)
+  logger.debug('DCL API request parameters', {
+    url: DCL_API_URL,
+    method: 'POST',
+    key: dclApiKey ? `${dclApiKey.substring(0, 4)}...${dclApiKey.substring(dclApiKey.length - 4)}` : null,
+    limit: requestBody.limit,
+    qsl_since: requestBody.qsl_since,
+    qso_since: requestBody.qso_since,
+    cnf_only: requestBody.cnf_only,
+  });
+
   try {
     const controller = new AbortController();
     const timeoutId = setTimeout(() => controller.abort(), REQUEST_TIMEOUT);

src/backend/services/job-queue.service.js

@@ -19,20 +19,21 @@ export const JobStatus = {
 const activeJobs = new Map();
 
 /**
- * Enqueue a new LoTW sync job
+ * Enqueue a new sync job
  * @param {number} userId - User ID
+ * @param {string} jobType - Type of job ('lotw_sync' or 'dcl_sync')
  * @returns {Promise<Object>} Job object with ID
  */
-export async function enqueueJob(userId) {
+export async function enqueueJob(userId, jobType = 'lotw_sync') {
-  logger.debug('Enqueueing LoTW sync job', { userId });
+  logger.debug('Enqueueing sync job', { userId, jobType });
 
-  // Check for existing active job
+  // Check for existing active job of the same type
-  const existingJob = await getUserActiveJob(userId);
+  const existingJob = await getUserActiveJob(userId, jobType);
   if (existingJob) {
-    logger.debug('Existing active job found', { jobId: existingJob.id });
+    logger.debug('Existing active job found', { jobId: existingJob.id, jobType });
     return {
       success: false,
-      error: 'A LoTW sync job is already running or pending for this user',
+      error: `A ${jobType} job is already running or pending for this user`,
       existingJob: existingJob.id,
     };
   }
@@ -42,16 +43,16 @@ export async function enqueueJob(userId) {
     .insert(syncJobs)
     .values({
       userId,
-      type: 'lotw_sync',
+      type: jobType,
       status: JobStatus.PENDING,
       createdAt: new Date(),
     })
     .returning();
 
-  logger.info('Job created', { jobId: job.id, userId });
+  logger.info('Job created', { jobId: job.id, userId, jobType });
 
   // Start processing asynchronously (don't await)
-  processJobAsync(job.id, userId).catch((error) => {
+  processJobAsync(job.id, userId, jobType).catch((error) => {
     logger.error(`Job processing error`, { jobId: job.id, error: error.message });
   });
 
@@ -68,15 +69,14 @@ export async function enqueueJob(userId) {
 }
 
 /**
- * Process a LoTW sync job asynchronously
+ * Process a sync job asynchronously
  * @param {number} jobId - Job ID
  * @param {number} userId - User ID
+ * @param {string} jobType - Type of job ('lotw_sync' or 'dcl_sync')
  */
-async function processJobAsync(jobId, userId) {
+async function processJobAsync(jobId, userId, jobType) {
   const jobPromise = (async () => {
     try {
-      // Import dynamically to avoid circular dependency
-      const { syncQSOs } = await import('./lotw.service.js');
       const { getUserById } = await import('./auth.service.js');
 
       // Update status to running
@@ -85,37 +85,72 @@ async function processJobAsync(jobId, userId) {
         startedAt: new Date(),
       });
 
-      // Get user credentials
+      let result;
-      const user = await getUserById(userId);
+
-      if (!user || !user.lotwUsername || !user.lotwPassword) {
+      if (jobType === 'dcl_sync') {
-        await updateJob(jobId, {
+        // Get user credentials
-          status: JobStatus.FAILED,
+        const user = await getUserById(userId);
-          completedAt: new Date(),
+        if (!user || !user.dclApiKey) {
-          error: 'LoTW credentials not configured',
+          await updateJob(jobId, {
+            status: JobStatus.FAILED,
+            completedAt: new Date(),
+            error: 'DCL credentials not configured',
+          });
+          return null;
+        }
+
+        // Get last QSL date for incremental sync
+        const { getLastDCLQSLDate, syncQSOs: syncDCLQSOs } = await import('./dcl.service.js');
+        const lastQSLDate = await getLastDCLQSLDate(userId);
+        const sinceDate = lastQSLDate || new Date('2000-01-01');
+
+        if (lastQSLDate) {
+          logger.info(`Job ${jobId}: DCL incremental sync`, { since: sinceDate.toISOString().split('T')[0] });
+        } else {
+          logger.info(`Job ${jobId}: DCL full sync`);
+        }
+
+        // Update job progress
+        await updateJobProgress(jobId, {
+          message: 'Fetching QSOs from DCL...',
+          step: 'fetch',
         });
-        return null;
-      }
 
-      // Get last QSL date for incremental sync
+        // Execute the sync
-      const { getLastLoTWQSLDate } = await import('./lotw.service.js');
+        result = await syncDCLQSOs(userId, user.dclApiKey, sinceDate, jobId);
-      const lastQSLDate = await getLastLoTWQSLDate(userId);
-      const sinceDate = lastQSLDate || new Date('2000-01-01');
-
-      if (lastQSLDate) {
-        logger.info(`Job ${jobId}: Incremental sync`, { since: sinceDate.toISOString().split('T')[0] });
       } else {
-        logger.info(`Job ${jobId}: Full sync`);
+        // LoTW sync (default)
+        const user = await getUserById(userId);
+        if (!user || !user.lotwUsername || !user.lotwPassword) {
+          await updateJob(jobId, {
+            status: JobStatus.FAILED,
+            completedAt: new Date(),
+            error: 'LoTW credentials not configured',
+          });
+          return null;
+        }
+
+        // Get last QSL date for incremental sync
+        const { getLastLoTWQSLDate, syncQSOs } = await import('./lotw.service.js');
+        const lastQSLDate = await getLastLoTWQSLDate(userId);
+        const sinceDate = lastQSLDate || new Date('2000-01-01');
+
+        if (lastQSLDate) {
+          logger.info(`Job ${jobId}: LoTW incremental sync`, { since: sinceDate.toISOString().split('T')[0] });
+        } else {
+          logger.info(`Job ${jobId}: LoTW full sync`);
+        }
+
+        // Update job progress
+        await updateJobProgress(jobId, {
+          message: 'Fetching QSOs from LoTW...',
+          step: 'fetch',
+        });
+
+        // Execute the sync
+        result = await syncQSOs(userId, user.lotwUsername, user.lotwPassword, sinceDate, jobId);
       }
 
-      // Update job progress
-      await updateJobProgress(jobId, {
-        message: 'Fetching QSOs from LoTW...',
-        step: 'fetch',
-      });
-
-      // Execute the sync
-      const result = await syncQSOs(userId, user.lotwUsername, user.lotwPassword, sinceDate, jobId);
-
       // Update job as completed
       await updateJob(jobId, {
         status: JobStatus.COMPLETED,
@@ -197,9 +232,10 @@ export async function getJobStatus(jobId) {
 /**
  * Get user's active job (pending or running)
  * @param {number} userId - User ID
+ * @param {string} jobType - Optional job type filter
  * @returns {Promise<Object|null>} Active job or null
  */
-export async function getUserActiveJob(userId) {
+export async function getUserActiveJob(userId, jobType = null) {
   const conditions = [
     eq(syncJobs.userId, userId),
     or(
@@ -208,6 +244,10 @@ export async function getUserActiveJob(userId) {
     ),
   ];
 
+  if (jobType) {
+    conditions.push(eq(syncJobs.type, jobType));
+  }
+
   const [job] = await db
     .select()
     .from(syncJobs)

src/frontend/src/lib/api.js

@@ -74,6 +74,8 @@ export const qsosAPI = {
 
   syncFromLoTW: () => apiRequest('/lotw/sync', { method: 'POST' }),
 
+  syncFromDCL: () => apiRequest('/dcl/sync', { method: 'POST' }),
+
   deleteAll: () => apiRequest('/qsos/all', { method: 'DELETE' }),
 };
 

src/frontend/src/routes/qsos/+page.svelte

@@ -13,11 +13,20 @@
   let pageSize = 100;
   let pagination = null;
 
-  // Job polling state
+  // Job polling state - LoTW
-  let syncJobId = null;
+  let lotwSyncJobId = null;
-  let syncStatus = null;
+  let lotwSyncStatus = null;
-  let syncProgress = null;
+  let lotwSyncProgress = null;
-  let pollingInterval = null;
+  let lotwPollingInterval = null;
+
+  // Job polling state - DCL
+  let dclSyncJobId = null;
+  let dclSyncStatus = null;
+  let dclSyncProgress = null;
+  let dclPollingInterval = null;
+
+  // Sync result
+  let syncResult = null;
 
   // Delete confirmation state
   let showDeleteConfirm = false;
@@ -34,14 +43,17 @@
     if (!$auth.user) return;
     await loadQSOs();
     await loadStats();
-    // Check for active job on mount
+    // Check for active jobs on mount
-    await checkActiveJob();
+    await checkActiveJobs();
   });
 
-  // Clean up polling interval on unmount
+  // Clean up polling intervals on unmount
   onDestroy(() => {
-    if (pollingInterval) {
+    if (lotwPollingInterval) {
-      clearInterval(pollingInterval);
+      clearInterval(lotwPollingInterval);
+    }
+    if (dclPollingInterval) {
+      clearInterval(dclPollingInterval);
     }
   });
 
@@ -76,98 +88,169 @@
     }
   }
 
-  async function checkActiveJob() {
+  async function checkActiveJobs() {
     try {
       const response = await jobsAPI.getActive();
       if (response.job) {
-        syncJobId = response.job.id;
+        const job = response.job;
-        syncStatus = response.job.status;
+        if (job.type === 'lotw_sync') {
-        // Start polling if job is running
+          lotwSyncJobId = job.id;
-        if (syncStatus === 'running' || syncStatus === 'pending') {
+          lotwSyncStatus = job.status;
-          startPolling(response.job.id);
+          if (lotwSyncStatus === 'running' || lotwSyncStatus === 'pending') {
+            startLoTWPolling(job.id);
+          }
+        } else if (job.type === 'dcl_sync') {
+          dclSyncJobId = job.id;
+          dclSyncStatus = job.status;
+          if (dclSyncStatus === 'running' || dclSyncStatus === 'pending') {
+            startDCLPolling(job.id);
+          }
         }
       }
     } catch (err) {
-      console.error('Failed to check active job:', err);
+      console.error('Failed to check active jobs:', err);
     }
   }
 
-  async function startPolling(jobId) {
+  async function startLoTWPolling(jobId) {
-    syncJobId = jobId;
+    lotwSyncJobId = jobId;
-    syncStatus = 'running';
+    lotwSyncStatus = 'running';
 
-    // Clear any existing interval
+    if (lotwPollingInterval) {
-    if (pollingInterval) {
+      clearInterval(lotwPollingInterval);
-      clearInterval(pollingInterval);
     }
 
-    // Poll every 2 seconds
+    lotwPollingInterval = setInterval(async () => {
-    pollingInterval = setInterval(async () => {
       try {
         const response = await jobsAPI.getStatus(jobId);
         const job = response.job;
 
-        syncStatus = job.status;
+        lotwSyncStatus = job.status;
-        syncProgress = job.result?.progress ? job.result : null;
+        lotwSyncProgress = job.result?.progress ? job.result : null;
 
         if (job.status === 'completed') {
-          clearInterval(pollingInterval);
+          clearInterval(lotwPollingInterval);
-          pollingInterval = null;
+          lotwPollingInterval = null;
-          syncJobId = null;
+          lotwSyncJobId = null;
-          syncProgress = null;
+          lotwSyncProgress = null;
-          syncStatus = null;
+          lotwSyncStatus = null;
 
-          // Reload QSOs and stats
           await loadQSOs();
           await loadStats();
 
-          // Show success message
           syncResult = {
             success: true,
+            source: 'LoTW',
             ...job.result,
           };
         } else if (job.status === 'failed') {
-          clearInterval(pollingInterval);
+          clearInterval(lotwPollingInterval);
-          pollingInterval = null;
+          lotwPollingInterval = null;
-          syncJobId = null;
+          lotwSyncJobId = null;
-          syncProgress = null;
+          lotwSyncProgress = null;
-          syncStatus = null;
+          lotwSyncStatus = null;
 
-          // Show error message
           syncResult = {
             success: false,
-            error: job.error || 'Sync failed',
+            source: 'LoTW',
+            error: job.error || 'LoTW sync failed',
           };
         }
       } catch (err) {
-        console.error('Failed to poll job status:', err);
+        console.error('Failed to poll LoTW job status:', err);
-        // Don't stop polling on error, might be temporary
       }
     }, 2000);
   }
 
-  async function handleSync() {
+  async function startDCLPolling(jobId) {
+    dclSyncJobId = jobId;
+    dclSyncStatus = 'running';
+
+    if (dclPollingInterval) {
+      clearInterval(dclPollingInterval);
+    }
+
+    dclPollingInterval = setInterval(async () => {
+      try {
+        const response = await jobsAPI.getStatus(jobId);
+        const job = response.job;
+
+        dclSyncStatus = job.status;
+        dclSyncProgress = job.result?.progress ? job.result : null;
+
+        if (job.status === 'completed') {
+          clearInterval(dclPollingInterval);
+          dclPollingInterval = null;
+          dclSyncJobId = null;
+          dclSyncProgress = null;
+          dclSyncStatus = null;
+
+          await loadQSOs();
+          await loadStats();
+
+          syncResult = {
+            success: true,
+            source: 'DCL',
+            ...job.result,
+          };
+        } else if (job.status === 'failed') {
+          clearInterval(dclPollingInterval);
+          dclPollingInterval = null;
+          dclSyncJobId = null;
+          dclSyncProgress = null;
+          dclSyncStatus = null;
+
+          syncResult = {
+            success: false,
+            source: 'DCL',
+            error: job.error || 'DCL sync failed',
+          };
+        }
+      } catch (err) {
+        console.error('Failed to poll DCL job status:', err);
+      }
+    }, 2000);
+  }
+
+  async function handleLoTWSync() {
     try {
       const response = await qsosAPI.syncFromLoTW();
 
       if (response.jobId) {
-        // Job was queued successfully
+        startLoTWPolling(response.jobId);
-        startPolling(response.jobId);
       } else if (response.existingJob) {
-        // There's already an active job
+        startLoTWPolling(response.existingJob);
-        startPolling(response.existingJob);
       } else {
-        throw new Error(response.error || 'Failed to queue sync job');
+        throw new Error(response.error || 'Failed to queue LoTW sync job');
       }
     } catch (err) {
       syncResult = {
         success: false,
+        source: 'LoTW',
         error: err.message,
       };
     }
   }
 
-  let syncResult = null;
+  async function handleDCLSync() {
+    try {
+      const response = await qsosAPI.syncFromDCL();
+
+      if (response.jobId) {
+        startDCLPolling(response.jobId);
+      } else if (response.existingJob) {
+        startDCLPolling(response.existingJob);
+      } else {
+        throw new Error(response.error || 'Failed to queue DCL sync job');
+      }
+    } catch (err) {
+      syncResult = {
+        success: false,
+        source: 'DCL',
+        error: err.message,
+      };
+    }
+  }
 
   async function applyFilters() {
     currentPage = 1;
@@ -263,31 +346,52 @@
         <button
           class="btn btn-danger"
           on:click={() => showDeleteConfirm = true}
-          disabled={syncStatus === 'running' || syncStatus === 'pending' || deleting}
+          disabled={lotwSyncStatus === 'running' || lotwSyncStatus === 'pending' || dclSyncStatus === 'running' || dclSyncStatus === 'pending' || deleting}
         >
           Clear All QSOs
         </button>
       {/if}
       <button
-        class="btn btn-primary"
+        class="btn btn-primary lotw-btn"
-        on:click={handleSync}
+        on:click={handleLoTWSync}
-        disabled={syncStatus === 'running' || syncStatus === 'pending' || deleting}
+        disabled={lotwSyncStatus === 'running' || lotwSyncStatus === 'pending' || deleting}
       >
-        {#if syncStatus === 'running' || syncStatus === 'pending'}
+        {#if lotwSyncStatus === 'running' || lotwSyncStatus === 'pending'}
-          Syncing...
+          LoTW Syncing...
         {:else}
           Sync from LoTW
         {/if}
       </button>
+      <button
+        class="btn btn-primary dcl-btn"
+        on:click={handleDCLSync}
+        disabled={dclSyncStatus === 'running' || dclSyncStatus === 'pending' || deleting}
+      >
+        {#if dclSyncStatus === 'running' || dclSyncStatus === 'pending'}
+          DCL Syncing...
+        {:else}
+          Sync from DCL
+        {/if}
+      </button>
     </div>
   </div>
 
-  {#if syncProgress}
+  {#if lotwSyncProgress}
     <div class="alert alert-info">
       <h3>Syncing from LoTW...</h3>
-      <p>{syncProgress.message || 'Processing...'}</p>
+      <p>{lotwSyncProgress.message || 'Processing...'}</p>
-      {#if syncProgress.total}
+      {#if lotwSyncProgress.total}
-        <p>Progress: {syncProgress.processed || 0} / {syncProgress.total}</p>
+        <p>Progress: {lotwSyncProgress.processed || 0} / {lotwSyncProgress.total}</p>
+      {/if}
+    </div>
+  {/if}
+
+  {#if dclSyncProgress}
+    <div class="alert alert-info">
+      <h3>Syncing from DCL...</h3>
+      <p>{dclSyncProgress.message || 'Processing...'}</p>
+      {#if dclSyncProgress.total}
+        <p>Progress: {dclSyncProgress.processed || 0} / {dclSyncProgress.total}</p>
       {/if}
     </div>
   {/if}
@@ -602,6 +706,23 @@
   .header-buttons {
     display: flex;
     gap: 1rem;
+    flex-wrap: wrap;
+  }
+
+  .lotw-btn {
+    background-color: #4a90e2;
+  }
+
+  .lotw-btn:hover:not(:disabled) {
+    background-color: #357abd;
+  }
+
+  .dcl-btn {
+    background-color: #e67e22;
+  }
+
+  .dcl-btn:hover:not(:disabled) {
+    background-color: #d35400;
   }
 
   .stats-grid {

src/frontend/src/routes/settings/+page.svelte

@@ -194,8 +194,8 @@
   <div class="settings-section">
     <h2>DCL Credentials</h2>
     <p class="help-text">
-      Configure your DARC Community Logbook (DCL) API key for future sync functionality.
+      Configure your DARC Community Logbook (DCL) API key to sync your QSOs.
-      <strong>Note:</strong> DCL does not currently provide a download API. This is prepared for when they add one.
+      Your API key is stored securely and used only to fetch your confirmed QSOs.
     </p>
 
     {#if hasDCLCredentials}
@@ -220,7 +220,7 @@
           placeholder="Your DCL API key"
         />
         <p class="hint">
-          Enter your DCL API key for future sync functionality
+          Enter your DCL API key to sync QSOs
         </p>
       </div>
 
@@ -233,10 +233,10 @@
       <h3>About DCL</h3>
       <p>
         DCL (DARC Community Logbook) is DARC's web-based logbook system for German amateur radio awards.
-        It includes DOK (DARC Ortsverband Kennung) fields for local club awards.
+        It includes DOK (DARC Ortsverband Kennung) fields for local club awards like the DLD award.
       </p>
       <p>
-        <strong>Status:</strong> Download API not yet available.{' '}
+        Once configured, you can sync your QSOs from DCL on the QSO Log page.
         <a href="https://dcl.darc.de/" target="_blank" rel="noopener">
           Visit DCL website
         </a>