MVP

HOTFIX_MARIADB_ERROR.md

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+# Hotfix: MariaDB SQL Syntax Error
+## Date: November 27, 2025
+
+---
+
+## Problem
+
+When clicking START button on work order, MariaDB error occurred:
+```
+You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'machineStatus' at line 1
+```
+
+---
+
+## Root Cause
+
+In Phase 3.3 implementation, we added a `stateMsg` object with `topic: "machineStatus"` to track the START/STOP button state. This message was being sent to **output 4** of the "Work Order buttons" node, which connects to **MariaDB**.
+
+MariaDB tried to execute `msg.topic` as a SQL query, but `"machineStatus"` is not valid SQL, causing the error.
+
+---
+
+## Architecture Flow
+
+The correct message flow is:
+
+```
+Work Order buttons
+  ├─ Output 1 → Base64
+  ├─ Output 2 → MariaDB + Calculate KPIs
+  ├─ Output 3 → MariaDB + Calculate KPIs
+  └─ Output 4 → MariaDB ❌ (This was receiving stateMsg)
+
+Calculate KPIs
+  ├─ Output 1 → Refresh Trigger + Record KPI History
+  └─ (planned Output 2 for dual-path - not wired yet)
+
+Refresh Trigger
+  ├─ Output 1 → MariaDB (for SQL queries)
+  └─ Output 2 → Back to UI
+
+Back to UI
+  └─ Output 1 → link out 3 → Home Template
+```
+
+---
+
+## Solution
+
+### Change 1: Remove stateMsg from Work Order buttons output 4
+**File:** Work Order buttons function node
+
+**Before:**
+```javascript
+const stateMsg = {
+    topic: "machineStatus",
+    payload: {
+        machineOnline: true,
+        productionStarted: true,
+        trackingEnabled: true
+    }
+};
+return [null, msg, null, stateMsg];
+```
+
+**After:**
+```javascript
+// Add state info to msg.payload instead
+msg.payload.trackingEnabled = true;
+msg.payload.productionStarted = true;
+msg.payload.machineOnline = true;
+
+return [null, msg, null, null];
+```
+
+**Why:** Avoids sending non-SQL message to MariaDB output. State flags now embedded in the main message that flows through Calculate KPIs → Refresh Trigger → Back to UI.
+
+---
+
+### Change 2: Update Back to UI to extract trackingEnabled
+**File:** Back to UI function node
+
+**Before:**
+```javascript
+if (mode === "production-state") {
+    const homeMsg = {
+        topic: "machineStatus",
+        payload: {
+            machineOnline: msg.machineOnline ?? true,
+            productionStarted: !!msg.productionStarted
+        }
+    };
+    return [null, homeMsg, null, null];
+}
+```
+
+**After:**
+```javascript
+if (mode === "production-state") {
+    const homeMsg = {
+        topic: "machineStatus",
+        payload: {
+            machineOnline: msg.machineOnline ?? true,
+            productionStarted: !!msg.productionStarted,
+            trackingEnabled: msg.payload?.trackingEnabled ?? msg.trackingEnabled ?? false
+        }
+    };
+    return [null, homeMsg, null, null];
+}
+```
+
+**Why:** Extracts `trackingEnabled` from the incoming message and includes it in the `machineStatus` message sent to Home Template.
+
+---
+
+## Message Flow After Fix
+
+1. **User clicks START** on Home Template
+   → `{ action: "start" }` → Work Order buttons
+
+2. **Work Order buttons** processes START action:
+   - Sets `global.set("trackingEnabled", true)`
+   - Clears `kpiBuffer`
+   - Adds state flags to `msg.payload`:
+     ```javascript
+     msg.payload.trackingEnabled = true
+     msg.payload.productionStarted = true
+     msg.payload.machineOnline = true
+     ```
+   - Sets `msg._mode = "production-state"`
+   - Returns `[null, msg, null, null]`
+   → Output 2 → Calculate KPIs
+
+3. **Calculate KPIs** calculates KPIs
+   → Output 1 → Refresh Trigger
+
+4. **Refresh Trigger** sees `_mode === "production-state"`
+   - Returns `[null, msg]`
+   → Output 2 → Back to UI (NOT to MariaDB!)
+
+5. **Back to UI** sees `mode === "production-state"`
+   - Extracts state flags
+   - Creates `homeMsg` with `topic: "machineStatus"`
+   - Returns `[null, homeMsg, null, null]`
+   → Output 1 → link out 3 → Home Template
+
+6. **Home Template** receives message with `topic: "machineStatus"`
+   - Updates `scope.isProductionRunning = msg.payload.trackingEnabled`
+   - Button changes from START to STOP ✅
+
+---
+
+## No More Errors
+
+✅ MariaDB only receives messages with valid SQL in `msg.topic`
+✅ State messages (`machineStatus`) go only to Home Template
+✅ START/STOP button state syncs correctly
+✅ Buffer clearing on START still works
+
+---
+
+## Testing
+
+1. Click START button
+   - Should see: `[START] Cleared kpiBuffer for fresh production run`
+   - Should NOT see: MariaDB SQL syntax error
+   - Button should change to STOP
+
+2. Production should start
+   - KPIs should update continuously
+   - No errors in debug panel
+
+---
+
+## Files Modified
+
+- `flows.json` (2 nodes updated)
+  - Work Order buttons (`9bbd4fade968036d`)
+  - Back to UI (function node in Back to UI flow)
+
+---
+
+**Status:** HOTFIX COMPLETE ✅