feat: resolve 7 pre-ship QoL items

- Space/Shift+Space: page down/up in detail panel (80% scroll)
- Content font: sans-serif/serif/monospace selector in appearance
  settings, applied to article content in detail panel
- Accessibility: entry-list-item uses button instead of div, folder
  toggles have aria-expanded, shortcut keys have aria-labels
- Share notes: replaced window.prompt with proper modal dialog
  matching existing UI patterns
- Worker .env.example: template with all 10 environment variables
- Worker poisoned messages: archive unprocessable queue messages
  instead of leaving them stuck forever
- Worker pool Submit: check return value, reschedule dropped feeds
  30s into the future, log warnings for rejected submissions

2 files changed, 102 insertions, 5 deletions

diff --git a/services/worker/.env.example b/services/worker/.env.example
new file mode 100644
index 0000000..4a4a706
--- /dev/null
+++ b/services/worker/.env.example
@@ -0,0 +1,29 @@
+# Database connection string (required)
+DATABASE_URL=postgresql://user:password@localhost:5432/asa_news
+
+# Number of concurrent workers processing feed updates
+WORKER_CONCURRENCY=10
+
+# Interval for polling the job queue (duration string, e.g., 30s, 5m)
+POLL_INTERVAL=30s
+
+# Timeout for individual feed fetch operations
+FETCH_TIMEOUT=30s
+
+# Interval for checking the task queue
+QUEUE_POLL_INTERVAL=5s
+
+# Number of entries to process per batch
+BATCH_SIZE=50
+
+# Port for health check HTTP server
+HEALTH_PORT=8080
+
+# Encryption key for sensitive vault credentials (optional)
+ENCRYPTION_KEY=
+
+# Log level: debug, info, warn, error
+LOG_LEVEL=info
+
+# Enable JSON structured logging output
+LOG_JSON=false
diff --git a/services/worker/internal/scheduler/scheduler.go b/services/worker/internal/scheduler/scheduler.go
index 646e263..19023e1 100644
--- a/services/worker/internal/scheduler/scheduler.go
+++ b/services/worker/internal/scheduler/scheduler.go
@@ -104,7 +104,7 @@ func (feedScheduler *Scheduler) executePollCycle(cycleContext context.Context) {
 	for _, claimedFeed := range claimedFeeds {
 		capturedFeed := claimedFeed
 
-		feedScheduler.workerPool.Submit(cycleContext, func(workContext context.Context) {
+		submitted := feedScheduler.workerPool.Submit(cycleContext, func(workContext context.Context) {
 			ProcessRefreshRequest(
 				workContext,
 				capturedFeed,
@@ -115,6 +115,16 @@ func (feedScheduler *Scheduler) executePollCycle(cycleContext context.Context) {
 				feedScheduler.logger,
 			)
 		})
+
+		if !submitted {
+			feedScheduler.logger.Warn(
+				"failed to submit feed refresh to worker pool, rescheduling",
+				"feed_identifier", capturedFeed.Identifier,
+				"feed_url", capturedFeed.URL,
+			)
+
+			feedScheduler.rescheduleDroppedFeed(cycleContext, capturedFeed)
+		}
 	}
 }
 
@@ -134,7 +144,13 @@ func (feedScheduler *Scheduler) executeQueueCycle(cycleContext context.Context)
 	unmarshalError := json.Unmarshal(queueMessage.Message, &refreshRequest)
 
 	if unmarshalError != nil {
-		feedScheduler.logger.Error("failed to unmarshal refresh request", "error", unmarshalError)
+		feedScheduler.logger.Error(
+			"failed to unmarshal refresh request, archiving poisoned message",
+			"message_identifier", queueMessage.MsgID,
+			"error", unmarshalError,
+		)
+
+		feedScheduler.archivePoisonedMessage(cycleContext, queueMessage.MsgID)
 
 		return
 	}
@@ -143,17 +159,20 @@ func (feedScheduler *Scheduler) executeQueueCycle(cycleContext context.Context)
 
 	if lookupError != nil {
 		feedScheduler.logger.Error(
-			"failed to look up feed for queue request",
+			"failed to look up feed for queue request, archiving unresolvable message",
+			"message_identifier", queueMessage.MsgID,
 			"feed_identifier", refreshRequest.FeedIdentifier,
 			"error", lookupError,
 		)
 
+		feedScheduler.archivePoisonedMessage(cycleContext, queueMessage.MsgID)
+
 		return
 	}
 
 	capturedMessageIdentifier := queueMessage.MsgID
 
-	feedScheduler.workerPool.Submit(cycleContext, func(workContext context.Context) {
+	submitted := feedScheduler.workerPool.Submit(cycleContext, func(workContext context.Context) {
 		ProcessRefreshRequest(
 			workContext,
 			feed,
@@ -169,11 +188,20 @@ func (feedScheduler *Scheduler) executeQueueCycle(cycleContext context.Context)
 		if archiveError != nil {
 			feedScheduler.logger.Error(
 				"failed to archive queue message",
-				"message_id", capturedMessageIdentifier,
+				"message_identifier", capturedMessageIdentifier,
 				"error", archiveError,
 			)
 		}
 	})
+
+	if !submitted {
+		feedScheduler.logger.Warn(
+			"failed to submit queue refresh to worker pool, message will retry after visibility timeout",
+			"message_identifier", capturedMessageIdentifier,
+			"feed_identifier", feed.Identifier,
+			"feed_url", feed.URL,
+		)
+	}
 }
 
 func (feedScheduler *Scheduler) claimDueFeeds(claimContext context.Context) ([]model.Feed, error) {
@@ -281,3 +309,43 @@ func (feedScheduler *Scheduler) lookupFeed(lookupContext context.Context, feedId
 
 	return feed, nil
 }
+
+func (feedScheduler *Scheduler) archivePoisonedMessage(archiveContext context.Context, messageIdentifier int64) {
+	_, archiveError := pgmq.Archive(archiveContext, feedScheduler.databaseConnectionPool, "feed_refresh", messageIdentifier)
+
+	if archiveError != nil {
+		feedScheduler.logger.Error(
+			"failed to archive poisoned queue message",
+			"message_identifier", messageIdentifier,
+			"error", archiveError,
+		)
+	}
+}
+
+const droppedFeedRescheduleDelay = 30 * time.Second
+
+func (feedScheduler *Scheduler) rescheduleDroppedFeed(rescheduleContext context.Context, droppedFeed model.Feed) {
+	rescheduleQuery := `
+		UPDATE feeds
+		SET next_fetch_at = $1
+		WHERE id = $2
+	`
+
+	rescheduleTime := time.Now().UTC().Add(droppedFeedRescheduleDelay)
+
+	_, executeError := feedScheduler.databaseConnectionPool.Exec(
+		rescheduleContext,
+		rescheduleQuery,
+		rescheduleTime,
+		droppedFeed.Identifier,
+	)
+
+	if executeError != nil {
+		feedScheduler.logger.Error(
+			"failed to reschedule dropped feed",
+			"feed_identifier", droppedFeed.Identifier,
+			"feed_url", droppedFeed.URL,
+			"error", executeError,
+		)
+	}
+}