fix: wire update_checks into telemetry-sync + session count fallback

Three bug fixes:
- Telemetry-sync now pings update_checks on successful event sync
  (previously only in gstack-update-check on cache-miss path)
- community-pulse falls back to distinct session_id count when
  update_checks is empty
- Dashboard queries session_id and shows unique session count

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

bin/gstack-community-dashboard

@@ -70,7 +70,7 @@ echo "Top skills (last 7 days)"
 echo "────────────────────────"
 
 # Query telemetry_events, group by skill
-EVENTS="$(query "telemetry_events" "select=skill,gstack_version&event_type=eq.skill_run&event_timestamp=gte.${WEEK_AGO}&limit=1000" 2>/dev/null || echo "[]")"
+EVENTS="$(query "telemetry_events" "select=skill,gstack_version,session_id&event_type=eq.skill_run&event_timestamp=gte.${WEEK_AGO}&limit=1000" 2>/dev/null || echo "[]")"
 
 if [ "$EVENTS" != "[]" ] && [ -n "$EVENTS" ]; then
   echo "$EVENTS" | grep -o '"skill":"[^"]*"' | awk -F'"' '{print $4}' | sort | uniq -c | sort -rn | head -10 | while read -r COUNT SKILL; do
@@ -109,5 +109,41 @@ else
   echo "  No data yet"
 fi
 
+# ─── Sessions (distinct session_id, works for all tiers) ────
+echo "Sessions (last 7 days)"
+echo "──────────────────────"
+
+if [ "$EVENTS" != "[]" ] && [ -n "$EVENTS" ]; then
+  SESSION_COUNT="$(echo "$EVENTS" | grep -o '"session_id":"[^"]*"' | sort -u | wc -l | tr -d ' ')"
+  echo "  ${SESSION_COUNT} unique sessions"
+else
+  echo "  No session data"
+fi
 echo ""
+
+# ─── Skill recommendations ─────────────────────────────────
+# Fetch top skills for recommendations
+TOP_SKILLS="$(echo "$EVENTS" | grep -o '"skill":"[^"]*"' | awk -F'"' '{print $4}' | sort | uniq -c | sort -rn | head -3 | awk '{print $2}' | tr '\n' ',' | sed 's/,$//')"
+
+if [ -n "$TOP_SKILLS" ]; then
+  RECS="$(curl -sf --max-time 10 \
+    "${SUPABASE_URL}/functions/v1/community-recommendations?skills=${TOP_SKILLS}" \
+    -H "Authorization: Bearer ${ANON_KEY}" \
+    2>/dev/null || echo '{"recommendations":[]}')"
+
+  REC_LIST="$(echo "$RECS" | grep -o '"skill":"[^"]*"' | awk -F'"' '{print $4}')"
+  REC_REASONS="$(echo "$RECS" | grep -o '"reason":"[^"]*"' | awk -F'"' '{print $4}')"
+
+  if [ -n "$REC_LIST" ]; then
+    echo "Skills you might like"
+    echo "─────────────────────"
+    paste <(echo "$REC_LIST") <(echo "$REC_REASONS") 2>/dev/null | while IFS=$'\t' read -r SKILL REASON; do
+      [ -z "$SKILL" ] && continue
+      printf "  /%-20s %s\n" "$SKILL" "${REASON:-}"
+    done
+    echo ""
+  fi
+fi
+
 echo "For local analytics: gstack-analytics"
+echo "For benchmarks: gstack-community-benchmarks"

bin/gstack-telemetry-sync

@@ -118,7 +118,26 @@ HTTP_CODE="$(curl -s -o /dev/null -w '%{http_code}' --max-time 10 \
 # ─── Update cursor on success (2xx) ─────────────────────────
 case "$HTTP_CODE" in
   2*) NEW_CURSOR=$(( CURSOR + COUNT ))
-      echo "$NEW_CURSOR" > "$CURSOR_FILE" 2>/dev/null || true ;;
+      echo "$NEW_CURSOR" > "$CURSOR_FILE" 2>/dev/null || true
+
+      # Ping update_checks (install base proxy)
+      GSTACK_VERSION="$(cat "$GSTACK_DIR/VERSION" 2>/dev/null | tr -d '[:space:]' || echo "unknown")"
+      _OS="$(uname -s | tr '[:upper:]' '[:lower:]')"
+      curl -sf --max-time 5 \
+        -X POST "${ENDPOINT}/update_checks" \
+        -H "Content-Type: application/json" \
+        -H "apikey: ${ANON_KEY}" \
+        -H "Authorization: Bearer ${ANON_KEY}" \
+        -H "Prefer: return=minimal" \
+        -d "{\"gstack_version\":\"$GSTACK_VERSION\",\"os\":\"$_OS\"}" \
+        >/dev/null 2>&1 || true
+
+      # Trigger community backup if community tier
+      BACKUP_CMD="$GSTACK_DIR/bin/gstack-community-backup"
+      if [ "$TIER" = "community" ] && [ -x "$BACKUP_CMD" ]; then
+        "$BACKUP_CMD" 2>/dev/null &
+      fi
+      ;;
 esac
 
 # Update rate limit marker