Fix H2D Pro wrong nozzle routing causing extrusion motor overload (#245)

H2D Pro firmware interprets use_ams as a nozzle index when sent as
integer (1 = deputy nozzle) instead of boolean. Bambu Studio sends
use_ams: true (boolean) while using integers for calibration fields.
Bambuddy was converting all boolean fields to integers for H2D series,
routing filament to the deputy nozzle instead of main, causing
extrusion motor overload at ~75% print completion.

Keep use_ams as boolean for all printers, matching Bambu Studio format.

CHANGELOG.md

@@ -16,6 +16,7 @@ All notable changes to Bambuddy will be documented in this file.
 - **Spoolman Creates Duplicate Spools on Startup** ([#295](https://github.com/maziggy/bambuddy/pull/295)) — Each AMS tray independently fetched all spools from Spoolman, causing redundant API calls and duplicate spool creation with large databases (300+ spools). Now fetches spools once and reuses cached data across all tray operations. Added retry logic (3 attempts, 500ms delay) with connection recreation for transient network errors.
 - **Filament Usage Charts Inflated by Quantity Multiplier** ([#229](https://github.com/maziggy/bambuddy/issues/229)) — Daily, weekly, and filament-type charts were multiplying `filament_used_grams` by print quantity, even though the value already represents the total for the entire job. A 26-object print using 126g was counted as 3,276g. Removed the erroneous multiplier from three aggregations in `FilamentTrends.tsx`.
 - **Energy Cost Shows 0.00 in "Total Consumption" Mode** ([#284](https://github.com/maziggy/bambuddy/issues/284)) — Statistics Quick Stats showed 0.00 energy cost when Energy Display Mode was set to "Total Consumption" with Home Assistant smart plugs. The `homeassistant_service` was not configured with HA URL/token before querying plug energy data, causing it to silently return nothing.
+- **H2D Pro Prints Fail at ~75% With Extrusion Motor Overload** ([#245](https://github.com/maziggy/bambuddy/issues/245)) — H2D Pro firmware interprets `use_ams: 1` (integer) as a nozzle index, routing filament to the deputy nozzle instead of the main nozzle. Bambu Studio sends `use_ams: true` (boolean) while using integers for other fields. Fixed by keeping `use_ams` as boolean for all printers including H2D series.
 
 ### Documentation
 - **Proxy Mode Security Warning** — Added FTP data channel security warning to wiki, README, and website. Bambu Studio does not encrypt the FTP data channel despite negotiating PROT P; MQTT and FTP control channels are fully TLS-encrypted. VPN (Tailscale/WireGuard) recommended for full data encryption.

backend/app/services/bambu_mqtt.py

@@ -2049,8 +2049,10 @@ class BambuMQTTClient:
                         slot_id = tray_id % 4
                         ams_mapping2.append({"ams_id": ams_id, "slot_id": slot_id})
 
-            # H2D series requires integer values (0/1) for boolean fields
-            # Other printers (X1C, P1S, A1, etc.) require actual booleans
+            # H2D series requires integer values (0/1) for calibration/leveling fields
+            # but use_ams MUST remain boolean — H2D Pro firmware interprets integer
+            # values as nozzle index (1 = deputy nozzle), causing wrong extruder routing
+            # Other printers (X1C, P1S, A1, etc.) require actual booleans for all fields
             is_h2d = self.model and self.model.upper().strip() in ("H2D", "H2D PRO", "H2DPRO", "H2C", "H2S")
 
             command = {
@@ -2068,7 +2070,7 @@ class BambuMQTTClient:
                     "flow_cali": (1 if flow_cali else 0) if is_h2d else flow_cali,
                     "vibration_cali": (1 if vibration_cali else 0) if is_h2d else vibration_cali,
                     "layer_inspect": (1 if layer_inspect else 0) if is_h2d else layer_inspect,
-                    "use_ams": (1 if use_ams else 0) if is_h2d else use_ams,
+                    "use_ams": use_ams,
                     "cfg": "0",
                     "extrude_cali_flag": 0,
                     "extrude_cali_manual_mode": 0,
@@ -2082,7 +2084,10 @@ class BambuMQTTClient:
             }
 
             if is_h2d:
-                logger.info("[%s] H2D series detected: using integer format for boolean fields", self.serial_number)
+                logger.info(
+                    "[%s] H2D series detected: using integer format for calibration fields (use_ams stays boolean)",
+                    self.serial_number,
+                )
 
             # P2S-specific parameter adjustments
             # P2S printer doesn't support vibration calibration like X1/P1 series