Add CLAUDE.md with project instructions

Documents:
- Zabbix template requirements for ShopDB integration
- Supply item naming rules ("Level" in name, percentage values)
- YAML structure (triggers inside items, valid UUIDv4)
- Common import errors and fixes
- HID DTC4500e device-specific notes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

CLAUDE.md

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+# SNMP Scanner - Claude Code Instructions
+
+## Project Overview
+
+Repository for SNMP-based Zabbix templates and network device monitoring tools. Templates created here integrate with the ShopDB application for displaying supply levels.
+
+## Repository Location
+
+- **Local**: `/home/camp/projects/python/snmp-scanner/`
+- **Gitea**: `http://localhost:3000/cproudlock/snmp-scanner`
+
+## Key Files
+
+| File | Purpose |
+|------|---------|
+| `zabbix_template_*.yaml` | Zabbix monitoring templates |
+| `README.md` | Template guidelines for ShopDB integration |
+
+## Zabbix Template Requirements
+
+### For displayprinter.asp Compatibility
+
+Supply level items MUST follow these rules to appear in ShopDB:
+
+1. **Item name must contain "Level"**
+   ```yaml
+   name: Ribbon Level      # Good - will appear
+   name: Ribbon Remaining  # Bad - filtered out
+   ```
+
+2. **Value must be percentage (0-100)**
+   - Add preprocessing if SNMP returns raw counts
+   - Use JavaScript to convert: `(remaining / capacity) * 100`
+
+3. **Use `units: '%'`** for percentage values
+
+### Zabbix YAML Structure
+
+```yaml
+# UUIDs: 32 hex chars, no dashes
+uuid: 97f742974686406aa8be1394d18dcb5f
+
+# Triggers go INSIDE items, not at template level
+items:
+- uuid: abc123...
+  name: Some Item
+  triggers:          # Nested under the item
+  - uuid: def456...
+    expression: '...'
+```
+
+### Generating Valid UUIDs
+
+```bash
+python3 -c "import uuid; print(uuid.uuid4().hex)"
+```
+
+## Related Projects
+
+- **ShopDB**: `/home/camp/projects/windows/shopdb/`
+  - `includes/zabbix_all_supplies.asp` - Zabbix API integration
+  - `displayprinter.asp` - Displays supply levels from Zabbix
+
+## Common Tasks
+
+### Creating a New Template
+
+1. Get SNMP walk data from the device
+2. Identify relevant OIDs for monitoring
+3. Create YAML template following structure in existing templates
+4. Ensure supply items have "Level" in name and return percentages
+5. Generate valid UUIDv4 for all uuid fields
+6. Place triggers inside their related items
+
+### Testing Template Import
+
+1. Import into Zabbix via Configuration > Templates > Import
+2. Common errors:
+   - "unexpected tag triggers" = triggers at wrong level (move inside items)
+   - "invalid parameter uuid" = UUID not valid UUIDv4 format
+
+## Device-Specific Notes
+
+### HID Fargo DTC4500e Card Printer
+
+- **MIB**: HID Enterprise MIB (1.3.6.1.4.1.28959)
+- **Ribbon**: YMCKO 500-print capacity
+- **OID for ribbon**: 1.3.6.1.4.1.28959.3.255.1.16.0 (returns raw count)
+- **Status flags OID**: 1.3.6.1.4.1.28959.3.255.1.10.0
+  - Format: `DH:0 IH:0 LM:0 FL:1 MG:0 SM:0 SC:0 PE:0`
+  - DH=Door/Hopper, IH=Input Hopper, FL=Film loaded, etc.