build(plugins): cap concurrent CGO plugin builds

  * Limit default parallelism to four with DEVLAKE_PLUGIN_PARALLELISM override to reduce OOM on small hosts.
  * Add Cursor cost_reconciliation.sql queries and remove obsolete README rak_tools reference.

Signed-off-by: Joshua Smith <jbsmith7741@gmail.com>

Author: jbsmith7741

backend/plugins/cursor/README.md

@@ -135,8 +135,6 @@ Grafana dashboard JSON lives under `grafana/dashboards/mysql/`:
 | AI Cost Efficiency (Cursor panels) | `ai-cost-efficiency.json` | — |
 | Multi-AI Comparison (Cursor panels) | `multi-ai-comparison.json` | — |
 
-See `grafana/dashboards/mysql/cursor-usage.json` for the dashboard definition and [rak_tools/grafana.md](../../../rak_tools/grafana.md) for currency formatting and Grafana version notes.
-
 ## Error handling
 
 | Symptom | Likely cause |

backend/plugins/cursor/cost_reconciliation.sql

@@ -0,0 +1,41 @@
+-- Cursor cost reconciliation queries
+-- Run against the lake database after a full billing-cycle event backfill.
+--
+-- Note: SUM(charged_cents) from events only reconciles with /teams/spend when
+-- ALL usage events for the billing cycle are collected (paginate filtered-usage-events).
+
+-- Team-level rollup comparison
+SELECT
+  ROUND(SUM(spend_cents) / 100, 2) AS spend_usd,
+  ROUND(SUM(included_spend_cents) / 100, 2) AS included_usd,
+  ROUND(SUM(spend_cents + included_spend_cents) / 100, 2) AS total_cycle_usd
+FROM _tool_cursor_user_spend;
+
+SELECT
+  ROUND(SUM(charged_cents) / 100, 2) AS event_charged_usd,
+  ROUND(SUM(total_cents) / 100, 2) AS event_model_usd,
+  COUNT(*) AS event_count,
+  MIN(event_time) AS earliest_event,
+  MAX(event_time) AS latest_event
+FROM _tool_cursor_usage_events;
+
+-- Per-user: billing cycle spend vs event charged (since billing cycle start)
+SELECT
+  s.email,
+  ROUND(s.spend_cents / 100, 2) AS spend_usd,
+  ROUND(s.included_spend_cents / 100, 2) AS included_usd,
+  ROUND((s.spend_cents + s.included_spend_cents) / 100, 2) AS total_cycle_usd,
+  ROUND(COALESCE(SUM(e.charged_cents), 0) / 100, 2) AS event_charged_usd,
+  COUNT(e.event_id) AS event_count
+FROM _tool_cursor_user_spend s
+LEFT JOIN _tool_cursor_usage_events e
+  ON s.email = e.user_email
+ AND e.event_time >= s.billing_cycle_start
+GROUP BY s.email, s.spend_cents, s.included_spend_cents
+ORDER BY total_cycle_usd DESC;
+
+-- Users with events but no spend row (should be empty)
+SELECT DISTINCT e.user_email
+FROM _tool_cursor_usage_events e
+LEFT JOIN _tool_cursor_user_spend s ON e.user_email = s.email
+WHERE s.email IS NULL;

backend/scripts/build-plugins.sh

@@ -64,19 +64,29 @@ fi
 
 
 PIDS=""
+# Cap concurrent CGO plugin builds. Unbounded nproc OOMs Docker Desktop / small VMs.
+# Override with DEVLAKE_PLUGIN_PARALLELISM=N (default: min(4, nproc)).
+if [ -n "$DEVLAKE_PLUGIN_PARALLELISM" ]; then
+    PARALLELISM="$DEVLAKE_PLUGIN_PARALLELISM"
+else
+    PARALLELISM=4
+    if command -v nproc >/dev/null 2>&1; then
+        PARALLELISM=$(nproc)
+    elif command -v sysctl >/dev/null 2>&1; then
+        PARALLELISM=$(sysctl -n hw.ncpu)
+    fi
+    if [ "$PARALLELISM" -gt 4 ]; then
+        PARALLELISM=4
+    fi
+fi
+echo "Plugin build parallelism: $PARALLELISM"
 for PLUG in $PLUGINS; do
     NAME=$(basename $PLUG)
     echo "Building plugin $NAME to bin/plugins/$NAME/$NAME.so with args: $*  --gcflags="$GCFLAGS""
     go build -buildmode=plugin --gcflags="$GCFLAGS" -o $PLUGIN_OUTPUT_DIR/$NAME/$NAME.so $PLUG/*.go &
     PIDS="$PIDS $!"
     # avoid too many processes causing signal killed
     COUNT=$(echo "$PIDS" | wc -w)
-    PARALLELISM=4
-    if command -v nproc >/dev/null 2>&1; then
-        PARALLELISM=$(nproc)
-    elif command -v sysctl >/dev/null 2>&1; then
-        PARALLELISM=$(sysctl -n hw.ncpu)
-    fi
     if [ "$COUNT" -ge "$PARALLELISM" ]; then
         for PID in $PIDS; do
             wait $PID