Document version 1.2.1 release in VERSION.md

Added version 1.2.1 release notes detailing stability improvements, stack size increase, heap pre-allocation, and unified JSON sensor states.

CHANGELOG.md

@@ -1,5 +1,65 @@
 # EPrices – Changelog
 
+## v1.2.1 — 2026-04-07
+
+### ESP32 main task stack size increase
+
+Increased the FreeRTOS main application task stack from the ESP-IDF default
+of 8192 bytes to 16384 bytes. This eliminates the stack overflow scenario
+that most likely caused the spontaneous reboot observed in production on
+2026-04-06, where the FreeRTOS idle task faulted following memory pressure
+during a simultaneous NVS load and HTTP fetch/parse cycle.
+
+The 8 KB cost is well within the ESP32's 320 KB available RAM.
+
+**Changed location in `eprices.yaml`:**
+- `esp32: framework: sdkconfig_options:` — added
+  `CONFIG_ESP_MAIN_TASK_STACK_SIZE: "16384"`
+
+---
+
+### Price vector heap pre-allocation at boot
+
+Pre-allocated capacity for all four price vectors at boot using `.reserve(96)`.
+Previously, each vector started empty and grew incrementally on every NVS load
+and HTTP fetch, triggering repeated heap reallocations and leaving the heap
+fragmented before the first fetch cycle completed.
+
+With capacity reserved upfront, no reallocation occurs during any subsequent
+NVS load or HTTP parse operation. This reduces heap fragmentation and peak
+allocation spikes, particularly during the boot sequence where NVS load and
+the first HTTP fetch can overlap.
+
+**Vectors pre-allocated:**
+- `price_timestamps_today`
+- `price_values_today`
+- `price_timestamps_tomorrow`
+- `price_values_tomorrow`
+
+**Changed location in `eprices.yaml`:**
+- `on_boot:` lambda — added `.reserve(96)` on all four price vectors
+
+---
+
+### Hourly JSON sensor cleared state unified with 15-min sensors
+
+The two hourly JSON text sensors previously published `"[]"` when cleared
+(at midnight bridge and on `clear_today_prices` / `clear_tomorrow_prices`).
+The six 15-minute JSON sensors already published `""` in the same situation.
+All eight JSON sensors now publish `""` when cleared, giving consistent
+behaviour across the full sensor set.
+
+**Affected sensors:**
+- `Today JSON Hourly Prices EUR⁄kWh`
+- `Tomorrow JSON Hourly Prices EUR⁄kWh`
+
+**Changed locations in `eprices.yaml`:**
+- `clear_today_prices` script — `"[]"` → `""`
+- `clear_tomorrow_prices` script — `"[]"` → `""`
+- `midnight_bridge_promotion` script — `"[]"` → `""` (where applicable)
+
+---
+
 ## v1.2 — 2026-04-06
 
 ### HTTP fetch stuck-flag watchdog
@@ -179,10 +239,10 @@ eprices_vat_rate          # e.g. "0.22"  (VAT rate as decimal multiplier)
 
 | Name | Entity ID | Notes |
 |---|---|---|
-| Today JSON Hourly Prices EUR⁄kWh | `sensor.eprices_today_json_hourly_prices_eur_kwh` | JSON array, 24 values |
-| Today JSON 15-Min Prices EUR⁄kWh (P1 00:00-07:45) | `sensor.eprices_today_json_15_min_prices_eur_kwh_p1_00_00_07_45` | JSON array, 32 values |
-| Today JSON 15-Min Prices EUR⁄kWh (P2 08:00-15:45) | `sensor.eprices_today_json_15_min_prices_eur_kwh_p2_08_00_15_45` | JSON array, 32 values |
-| Today JSON 15-Min Prices EUR⁄kWh (P3 16:00-23:45) | `sensor.eprices_today_json_15_min_prices_eur_kwh_p3_16_00_23_45` | JSON array, 32 values |
+| Today JSON Hourly Prices EUR⁄kWh | `sensor.eprices_today_json_hourly_prices_eur_kwh` | JSON array, 24 values; `""` when no data |
+| Today JSON 15-Min Prices EUR⁄kWh (P1 00:00-07:45) | `sensor.eprices_today_json_15_min_prices_eur_kwh_p1_00_00_07_45` | JSON array, 32 values; `""` when no data |
+| Today JSON 15-Min Prices EUR⁄kWh (P2 08:00-15:45) | `sensor.eprices_today_json_15_min_prices_eur_kwh_p2_08_00_15_45` | JSON array, 32 values; `""` when no data |
+| Today JSON 15-Min Prices EUR⁄kWh (P3 16:00-23:45) | `sensor.eprices_today_json_15_min_prices_eur_kwh_p3_16_00_23_45` | JSON array, 32 values; `""` when no data |
 | Today Highest Price Time | `sensor.eprices_today_highest_price_time` | HH:MM |
 | Today Lowest Price Time | `sensor.eprices_today_lowest_price_time` | HH:MM |
 | Today Highest Hourly Price Time | `sensor.eprices_today_highest_hourly_price_time` | HH:00 |
@@ -194,10 +254,10 @@ eprices_vat_rate          # e.g. "0.22"  (VAT rate as decimal multiplier)
 | Today Price Update Status Message | `sensor.eprices_today_price_update_status_message` | Detailed status string; diagnostic |
 | Today API Fetch Attempts | `sensor.eprices_today_api_fetch_attempts` | HTTP fetch count; resets at midnight; diagnostic |
 | Today Entry Count | `sensor.eprices_today_entry_count` | Number of stored price points; diagnostic |
-| Tomorrow JSON Hourly Prices EUR⁄kWh | `sensor.eprices_tomorrow_json_hourly_prices_eur_kwh` | JSON array, 24 values |
-| Tomorrow JSON 15-Min Prices EUR⁄kWh (P1 00:00-07:45) | `sensor.eprices_tomorrow_json_15_min_prices_eur_kwh_p1_00_00_07_45` | JSON array, 32 values |
-| Tomorrow JSON 15-Min Prices EUR⁄kWh (P2 08:00-15:45) | `sensor.eprices_tomorrow_json_15_min_prices_eur_kwh_p2_08_00_15_45` | JSON array, 32 values |
-| Tomorrow JSON 15-Min Prices EUR⁄kWh (P3 16:00-23:45) | `sensor.eprices_tomorrow_json_15_min_prices_eur_kwh_p3_16_00_23_45` | JSON array, 32 values |
+| Tomorrow JSON Hourly Prices EUR⁄kWh | `sensor.eprices_tomorrow_json_hourly_prices_eur_kwh` | JSON array, 24 values; `""` when no data |
+| Tomorrow JSON 15-Min Prices EUR⁄kWh (P1 00:00-07:45) | `sensor.eprices_tomorrow_json_15_min_prices_eur_kwh_p1_00_00_07_45` | JSON array, 32 values; `""` when no data |
+| Tomorrow JSON 15-Min Prices EUR⁄kWh (P2 08:00-15:45) | `sensor.eprices_tomorrow_json_15_min_prices_eur_kwh_p2_08_00_15_45` | JSON array, 32 values; `""` when no data |
+| Tomorrow JSON 15-Min Prices EUR⁄kWh (P3 16:00-23:45) | `sensor.eprices_tomorrow_json_15_min_prices_eur_kwh_p3_16_00_23_45` | JSON array, 32 values; `""` when no data |
 | Tomorrow Highest Price Time | `sensor.eprices_tomorrow_highest_price_time` | HH:MM |
 | Tomorrow Lowest Price Time | `sensor.eprices_tomorrow_lowest_price_time` | HH:MM |
 | Tomorrow Highest Hourly Price Time | `sensor.eprices_tomorrow_highest_hourly_price_time` | HH:00 |
@@ -238,3 +298,4 @@ eprices_vat_rate          # e.g. "0.22"  (VAT rate as decimal multiplier)
 - **API fetch times** reset to `Never` at midnight bridge and on `clear_tomorrow_prices`
 - **API fetch attempt counters** reset to `0` at midnight and publish `0` immediately on boot
 - **Uptime** displayed as human-readable string: `45 s` / `5 min` / `3 h 22 min` / `12 d 4 h` / `4 months 12 d`
+- **JSON sensors** publish `""` (empty string) when no data is available — all eight JSON sensors behave consistently

ENTSO-E-PRICES-MIGRATION.md

@@ -85,96 +85,114 @@ The goal of EPrices was to:
 | Manual force update | Button | Button (unchanged) |
 | Midnight bridge | External HA automation at 00:00 | On-device `on_time: 00:00:00` |
 
+---
+
 ### Sensor naming
 
 All sensors were renamed with a systematic **Today / Tomorrow** prefix.
 The words "electricity" and "energy" were removed from all sensor names.
 "Next Day" was replaced with "Tomorrow" throughout.
 
+> **Note on entity ID slugs:** HA derives entity IDs by lower-casing the
+> sensor name and replacing spaces and special characters with underscores.
+> The `⁄` character in JSON sensor names may have been rendered differently
+> by older ESPHome versions — verify those specific IDs against your actual
+> HA instance if needed.
+
+---
+
 #### Numeric sensors
 
-| entso-e-prices v4.3.1 name | EPrices v1.0 name |
-|---|---|
-| `Current Electricity Price` | `Today Current Price` |
-| `Next Electricity Price` | `Today Next Price` |
-| `Average Electricity Price Today` | `Today Average Price` |
-| `Highest Electricity Price Today` | `Today Highest Price` |
-| `Lowest Electricity Price Today` | `Today Lowest Price` |
-| `Current Hourly Electricity Price` | `Today Current Hourly Price` |
-| `Next Hourly Electricity Price` | `Today Next Hourly Price` |
-| `Highest Hourly Electricity Price Today` | `Today Highest Hourly Price` |
-| `Lowest Hourly Electricity Price Today` | `Today Lowest Hourly Price` |
-| `Current Max Hourly Price Percentage` | `Today Current Max Hourly Price Percentage` |
-| `Daily Price Update Attempts` | `Today API Fetch Attempts` *(moved to text_sensor)* |
-| `Today Entry Count` | `Today Entry Count` *(moved to text_sensor)* |
-| `Next Day Current Electricity Price` | `Tomorrow Current Price` |
-| `Next Day Next Electricity Price` | `Tomorrow Next Price` |
-| `Average Electricity Price Tomorrow` | `Tomorrow Average Price` |
-| `Highest Electricity Price Tomorrow` | `Tomorrow Highest Price` |
-| `Lowest Electricity Price Tomorrow` | `Tomorrow Lowest Price` |
-| `Current Hourly Electricity Price Tomorrow` | `Tomorrow Current Hourly Price` |
-| `Next Hourly Electricity Price Tomorrow` | `Tomorrow Next Hourly Price` |
-| `Highest Hourly Electricity Price Tomorrow` | `Tomorrow Highest Hourly Price` |
-| `Lowest Hourly Electricity Price Tomorrow` | `Tomorrow Lowest Hourly Price` |
-| `Next Day Current Max Hourly Price Percentage` | `Tomorrow Current Max Hourly Price Percentage` |
-| `Next Day Price Update Attempts` | `Tomorrow API Fetch Attempts` *(moved to text_sensor)* |
-| `Tomorrow Entry Count` | `Tomorrow Entry Count` *(moved to text_sensor)* |
+| entso-e-prices v4.3.1 name | v4.3.1 entity ID | EPrices v1.2 name | EPrices v1.2 entity ID |
+|---|---|---|---|
+| `Current Electricity Price` | `sensor.entso_e_prices_current_electricity_price` | `Today Current Price` | `sensor.eprices_today_current_price` |
+| `Next Electricity Price` | `sensor.entso_e_prices_next_electricity_price` | `Today Next Price` | `sensor.eprices_today_next_price` |
+| `Average Electricity Price Today` | `sensor.entso_e_prices_average_electricity_price_today` | `Today Average Price` | `sensor.eprices_today_average_price` |
+| `Highest Electricity Price Today` | `sensor.entso_e_prices_highest_electricity_price_today` | `Today Highest Price` | `sensor.eprices_today_highest_price` |
+| `Lowest Electricity Price Today` | `sensor.entso_e_prices_lowest_electricity_price_today` | `Today Lowest Price` | `sensor.eprices_today_lowest_price` |
+| `Current Hourly Electricity Price` | `sensor.entso_e_prices_current_hourly_electricity_price` | `Today Current Hourly Price` | `sensor.eprices_today_current_hourly_price` |
+| `Next Hourly Electricity Price` | `sensor.entso_e_prices_next_hourly_electricity_price` | `Today Next Hourly Price` | `sensor.eprices_today_next_hourly_price` |
+| `Highest Hourly Electricity Price Today` | `sensor.entso_e_prices_highest_hourly_electricity_price_today` | `Today Highest Hourly Price` | `sensor.eprices_today_highest_hourly_price` |
+| `Lowest Hourly Electricity Price Today` | `sensor.entso_e_prices_lowest_hourly_electricity_price_today` | `Today Lowest Hourly Price` | `sensor.eprices_today_lowest_hourly_price` |
+| `Current Max Hourly Price Percentage` | `sensor.entso_e_prices_current_max_hourly_price_percentage` | `Today Current Max Hourly Price Percentage` | `sensor.eprices_today_current_max_hourly_price_percentage` |
+| `Daily Price Update Attempts` | `sensor.entso_e_prices_daily_price_update_attempts` | `Today API Fetch Attempts` *(moved to text_sensor)* | `sensor.eprices_today_api_fetch_attempts` |
+| `Today Entry Count` | `sensor.entso_e_prices_today_entry_count` | `Today Entry Count` *(moved to text_sensor)* | `sensor.eprices_today_entry_count` |
+| `Next Day Current Electricity Price` | `sensor.entso_e_prices_next_day_current_electricity_price` | `Tomorrow Current Price` | `sensor.eprices_tomorrow_current_price` |
+| `Next Day Next Electricity Price` | `sensor.entso_e_prices_next_day_next_electricity_price` | `Tomorrow Next Price` | `sensor.eprices_tomorrow_next_price` |
+| `Average Electricity Price Tomorrow` | `sensor.entso_e_prices_average_electricity_price_tomorrow` | `Tomorrow Average Price` | `sensor.eprices_tomorrow_average_price` |
+| `Highest Electricity Price Tomorrow` | `sensor.entso_e_prices_highest_electricity_price_tomorrow` | `Tomorrow Highest Price` | `sensor.eprices_tomorrow_highest_price` |
+| `Lowest Electricity Price Tomorrow` | `sensor.entso_e_prices_lowest_electricity_price_tomorrow` | `Tomorrow Lowest Price` | `sensor.eprices_tomorrow_lowest_price` |
+| `Current Hourly Electricity Price Tomorrow` | `sensor.entso_e_prices_current_hourly_electricity_price_tomorrow` | `Tomorrow Current Hourly Price` | `sensor.eprices_tomorrow_current_hourly_price` |
+| `Next Hourly Electricity Price Tomorrow` | `sensor.entso_e_prices_next_hourly_electricity_price_tomorrow` | `Tomorrow Next Hourly Price` | `sensor.eprices_tomorrow_next_hourly_price` |
+| `Highest Hourly Electricity Price Tomorrow` | `sensor.entso_e_prices_highest_hourly_electricity_price_tomorrow` | `Tomorrow Highest Hourly Price` | `sensor.eprices_tomorrow_highest_hourly_price` |
+| `Lowest Hourly Electricity Price Tomorrow` | `sensor.entso_e_prices_lowest_hourly_electricity_price_tomorrow` | `Tomorrow Lowest Hourly Price` | `sensor.eprices_tomorrow_lowest_hourly_price` |
+| `Next Day Current Max Hourly Price Percentage` | `sensor.entso_e_prices_next_day_current_max_hourly_price_percentage` | `Tomorrow Current Max Hourly Price Percentage` | `sensor.eprices_tomorrow_current_max_hourly_price_percentage` |
+| `Next Day Price Update Attempts` | `sensor.entso_e_prices_next_day_price_update_attempts` | `Tomorrow API Fetch Attempts` *(moved to text_sensor)* | `sensor.eprices_tomorrow_api_fetch_attempts` |
+| `Tomorrow Entry Count` | `sensor.entso_e_prices_tomorrow_entry_count` | `Tomorrow Entry Count` *(moved to text_sensor)* | `sensor.eprices_tomorrow_entry_count` |
+
+---
 
 #### Text sensors
 
-| entso-e-prices v4.3.1 name | EPrices v1.0 name |
-|---|---|
-| `ENTSO-E Hourly Prices EUR⁄kWh JSON` | `Today JSON Hourly Prices EUR⁄kWh` |
-| `ENTSO-E 15-Min Prices EUR⁄kWh JSON (P1 00:00-07:45)` | `Today JSON 15-Min Prices EUR⁄kWh (P1 00:00-07:45)` |
-| `ENTSO-E 15-Min Prices EUR⁄kWh JSON (P2 08:00-15:45)` | `Today JSON 15-Min Prices EUR⁄kWh (P2 08:00-15:45)` |
-| `ENTSO-E 15-Min Prices EUR⁄kWh JSON (P3 16:00-23:45)` | `Today JSON 15-Min Prices EUR⁄kWh (P3 16:00-23:45)` |
-| `Time Of Highest Energy Price Today` | `Today Highest Price Time` |
-| `Time Of Lowest Energy Price Today` | `Today Lowest Price Time` |
-| `Time Of Highest Hourly Energy Price Today` | `Today Highest Hourly Price Time` |
-| `Time Of Lowest Hourly Energy Price Today` | `Today Lowest Hourly Price Time` |
-| `Price Update Status` | `Today Price Update Status` |
-| `Last Price Update Time` | `Today Data Loaded Time` |
-| `Price Update Status Message` | `Today Price Update Status Message` |
-| `Current Price Status` | `Today Current Price Status` |
-| `ENTSO-E Next Day Hourly Prices EUR⁄kWh JSON` | `Tomorrow JSON Hourly Prices EUR⁄kWh` |
-| `ENTSO-E Next Day 15-Min Prices EUR⁄kWh JSON (P1 00:00-07:45)` | `Tomorrow JSON 15-Min Prices EUR⁄kWh (P1 00:00-07:45)` |
-| `ENTSO-E Next Day 15-Min Prices EUR⁄kWh JSON (P2 08:00-15:45)` | `Tomorrow JSON 15-Min Prices EUR⁄kWh (P2 08:00-15:45)` |
-| `ENTSO-E Next Day 15-Min Prices EUR⁄kWh JSON (P3 16:00-23:45)` | `Tomorrow JSON 15-Min Prices EUR⁄kWh (P3 16:00-23:45)` |
-| `Time Of Highest Energy Price Tomorrow` | `Tomorrow Highest Price Time` |
-| `Time Of Lowest Energy Price Tomorrow` | `Tomorrow Lowest Price Time` |
-| `Time Of Highest Hourly Energy Price Tomorrow` | `Tomorrow Highest Hourly Price Time` |
-| `Time Of Lowest Hourly Energy Price Tomorrow` | `Tomorrow Lowest Hourly Price Time` |
-| `Next Day Price Update Status` | `Tomorrow Price Update Status` |
-| `Next Day Last Price Update Time` | `Tomorrow Data Loaded Time` |
-| `Next Day Price Update Status Message` | `Tomorrow Price Update Status Message` |
-| `Next Day Current Price Status` | `Tomorrow Current Price Status` |
-| `ENTSO-E Last Reboot` | `Last Reboot` |
-| `Entso-E Today NVS Status` | `Today NVS Status` |
-| `Entso-E Tomorrow NVS Status` | `Tomorrow NVS Status` |
-| `ENTSO-E Last Update Source` | `Last Update Source` |
-| `Today Data Date` | `Today Data Date` *(unchanged)* |
-| `Tomorrow Data Date` | `Tomorrow Data Date` *(unchanged)* |
+| entso-e-prices v4.3.1 name | v4.3.1 entity ID | EPrices v1.2 name | EPrices v1.2 entity ID |
+|---|---|---|---|
+| `ENTSO-E Hourly Prices EUR⁄kWh JSON` | `sensor.entso_e_prices_entso_e_hourly_prices_eur_kwh_json` | `Today JSON Hourly Prices EUR⁄kWh` | `sensor.eprices_today_json_hourly_prices_eur_kwh` |
+| `ENTSO-E 15-Min Prices EUR⁄kWh JSON (P1 00:00-07:45)` | `sensor.entso_e_prices_entso_e_15_min_prices_eur_kwh_json_p1_00_00_07_45` | `Today JSON 15-Min Prices EUR⁄kWh (P1 00:00-07:45)` | `sensor.eprices_today_json_15_min_prices_eur_kwh_p1_00_00_07_45` |
+| `ENTSO-E 15-Min Prices EUR⁄kWh JSON (P2 08:00-15:45)` | `sensor.entso_e_prices_entso_e_15_min_prices_eur_kwh_json_p2_08_00_15_45` | `Today JSON 15-Min Prices EUR⁄kWh (P2 08:00-15:45)` | `sensor.eprices_today_json_15_min_prices_eur_kwh_p2_08_00_15_45` |
+| `ENTSO-E 15-Min Prices EUR⁄kWh JSON (P3 16:00-23:45)` | `sensor.entso_e_prices_entso_e_15_min_prices_eur_kwh_json_p3_16_00_23_45` | `Today JSON 15-Min Prices EUR⁄kWh (P3 16:00-23:45)` | `sensor.eprices_today_json_15_min_prices_eur_kwh_p3_16_00_23_45` |
+| `Time Of Highest Energy Price Today` | `sensor.entso_e_prices_time_of_highest_energy_price_today` | `Today Highest Price Time` | `sensor.eprices_today_highest_price_time` |
+| `Time Of Lowest Energy Price Today` | `sensor.entso_e_prices_time_of_lowest_energy_price_today` | `Today Lowest Price Time` | `sensor.eprices_today_lowest_price_time` |
+| `Time Of Highest Hourly Energy Price Today` | `sensor.entso_e_prices_time_of_highest_hourly_energy_price_today` | `Today Highest Hourly Price Time` | `sensor.eprices_today_highest_hourly_price_time` |
+| `Time Of Lowest Hourly Energy Price Today` | `sensor.entso_e_prices_time_of_lowest_hourly_energy_price_today` | `Today Lowest Hourly Price Time` | `sensor.eprices_today_lowest_hourly_price_time` |
+| `Price Update Status` | `sensor.entso_e_prices_price_update_status` | `Today Price Update Status` | `sensor.eprices_today_price_update_status` |
+| `Last Price Update Time` | `sensor.entso_e_prices_last_price_update_time` | `Today Data Loaded Time` | `sensor.eprices_today_data_loaded_time` |
+| `Price Update Status Message` | `sensor.entso_e_prices_price_update_status_message` | `Today Price Update Status Message` | `sensor.eprices_today_price_update_status_message` |
+| `Current Price Status` | `sensor.entso_e_prices_current_price_status` | `Today Current Price Status` | `sensor.eprices_today_current_price_status` |
+| `ENTSO-E Next Day Hourly Prices EUR⁄kWh JSON` | `sensor.entso_e_prices_entso_e_next_day_hourly_prices_eur_kwh_json` | `Tomorrow JSON Hourly Prices EUR⁄kWh` | `sensor.eprices_tomorrow_json_hourly_prices_eur_kwh` |
+| `ENTSO-E Next Day 15-Min Prices EUR⁄kWh JSON (P1 00:00-07:45)` | `sensor.entso_e_prices_entso_e_next_day_15_min_prices_eur_kwh_json_p1_00_00_07_45` | `Tomorrow JSON 15-Min Prices EUR⁄kWh (P1 00:00-07:45)` | `sensor.eprices_tomorrow_json_15_min_prices_eur_kwh_p1_00_00_07_45` |
+| `ENTSO-E Next Day 15-Min Prices EUR⁄kWh JSON (P2 08:00-15:45)` | `sensor.entso_e_prices_entso_e_next_day_15_min_prices_eur_kwh_json_p2_08_00_15_45` | `Tomorrow JSON 15-Min Prices EUR⁄kWh (P2 08:00-15:45)` | `sensor.eprices_tomorrow_json_15_min_prices_eur_kwh_p2_08_00_15_45` |
+| `ENTSO-E Next Day 15-Min Prices EUR⁄kWh JSON (P3 16:00-23:45)` | `sensor.entso_e_prices_entso_e_next_day_15_min_prices_eur_kwh_json_p3_16_00_23_45` | `Tomorrow JSON 15-Min Prices EUR⁄kWh (P3 16:00-23:45)` | `sensor.eprices_tomorrow_json_15_min_prices_eur_kwh_p3_16_00_23_45` |
+| `Time Of Highest Energy Price Tomorrow` | `sensor.entso_e_prices_time_of_highest_energy_price_tomorrow` | `Tomorrow Highest Price Time` | `sensor.eprices_tomorrow_highest_price_time` |
+| `Time Of Lowest Energy Price Tomorrow` | `sensor.entso_e_prices_time_of_lowest_energy_price_tomorrow` | `Tomorrow Lowest Price Time` | `sensor.eprices_tomorrow_lowest_price_time` |
+| `Time Of Highest Hourly Energy Price Tomorrow` | `sensor.entso_e_prices_time_of_highest_hourly_energy_price_tomorrow` | `Tomorrow Highest Hourly Price Time` | `sensor.eprices_tomorrow_highest_hourly_price_time` |
+| `Time Of Lowest Hourly Energy Price Tomorrow` | `sensor.entso_e_prices_time_of_lowest_hourly_energy_price_tomorrow` | `Tomorrow Lowest Hourly Price Time` | `sensor.eprices_tomorrow_lowest_hourly_price_time` |
+| `Next Day Price Update Status` | `sensor.entso_e_prices_next_day_price_update_status` | `Tomorrow Price Update Status` | `sensor.eprices_tomorrow_price_update_status` |
+| `Next Day Last Price Update Time` | `sensor.entso_e_prices_next_day_last_price_update_time` | `Tomorrow Data Loaded Time` | `sensor.eprices_tomorrow_data_loaded_time` |
+| `Next Day Price Update Status Message` | `sensor.entso_e_prices_next_day_price_update_status_message` | `Tomorrow Price Update Status Message` | `sensor.eprices_tomorrow_price_update_status_message` |
+| `Next Day Current Price Status` | `sensor.entso_e_prices_next_day_current_price_status` | `Tomorrow Current Price Status` | `sensor.eprices_tomorrow_current_price_status` |
+| `ENTSO-E Last Reboot` | `sensor.entso_e_prices_entso_e_last_reboot` | `Last Reboot` | `sensor.eprices_last_reboot` |
+| `Entso-E Today NVS Status` | `sensor.entso_e_prices_entso_e_today_nvs_status` | `Today NVS Status` | `sensor.eprices_today_nvs_status` |
+| `Entso-E Tomorrow NVS Status` | `sensor.entso_e_prices_entso_e_tomorrow_nvs_status` | `Tomorrow NVS Status` | `sensor.eprices_tomorrow_nvs_status` |
+| `ENTSO-E Last Update Source` | `sensor.entso_e_prices_entso_e_last_update_source` | `Last Update Source` | `sensor.eprices_last_update_source` |
+| `Today Data Date` | `sensor.entso_e_prices_today_data_date` | `Today Data Date` *(unchanged)* | `sensor.eprices_today_data_date` |
+| `Tomorrow Data Date` | `sensor.entso_e_prices_tomorrow_data_date` | `Tomorrow Data Date` *(unchanged)* | `sensor.eprices_tomorrow_data_date` |
+
+---
 
 #### Buttons
 
-| entso-e-prices v4.3.1 name | EPrices v1.0 name |
-|---|---|
-| `Entso-E Force Update` | `Force Today's Update` |
-| `Entso-E Force Next Day Update` | `Force Tomorrow's Update` |
-| `Entso-E Reboot Device` | `Reboot Device` |
+| entso-e-prices v4.3.1 name | v4.3.1 entity ID | EPrices v1.2 name | EPrices v1.2 entity ID |
+|---|---|---|---|
+| `Entso-E Force Update` | `button.entso_e_prices_entso_e_force_update` | `Force Today's Update` | `button.eprices_force_today_s_update` |
+| `Entso-E Force Next Day Update` | `button.entso_e_prices_entso_e_force_next_day_update` | `Force Tomorrow's Update` | `button.eprices_force_tomorrow_s_update` |
+| `Entso-E Reboot Device` | `button.entso_e_prices_entso_e_reboot_device` | `Reboot Device` | `button.eprices_reboot_device` |
+
+---
 
 ### New sensors in EPrices v1.0 (no equivalent in v4.3.1)
 
-| Sensor | Purpose |
-|---|---|
-| `Today Last API Fetch Time` | Timestamp of last successful HTTP fetch for today |
-| `Tomorrow Last API Fetch Time` | Timestamp of last successful HTTP fetch for tomorrow |
-| `WiFi Signal` | RSSI in dBm |
-| `Uptime` | Human-readable uptime string |
+| EPrices v1.2 name | EPrices v1.2 entity ID | Purpose |
+|---|---|---|
+| `Today Last API Fetch Time` | `sensor.eprices_today_last_api_fetch_time` | Timestamp of last successful HTTP fetch for today |
+| `Tomorrow Last API Fetch Time` | `sensor.eprices_tomorrow_last_api_fetch_time` | Timestamp of last successful HTTP fetch for tomorrow |
+| `WiFi Signal` | `sensor.eprices_wifi_signal` | RSSI in dBm |
+| `Uptime` | `sensor.eprices_uptime` | Human-readable uptime string |
+
+---
 
 ### Sensor output changes
 
-| Sensor | v4.3.1 output | EPrices v1.0 output |
+| Sensor | v4.3.1 output | EPrices v1.2 output |
 |---|---|---|
 | `Last Reboot` | `Last reboot: 2026-04-04 20:10:10` | `2026-04-04 20:10:10` |
 | `Today NVS Status` | `Today NVS: Stored 96 pts for 2026-04-04` | `Stored 96 pts for 2026-04-04` |
@@ -186,23 +204,30 @@ The words "electricity" and "energy" were removed from all sensor names.
 | `Today Current Price Status` | `Valid` / `Missing` | `Valid` / `Missing` / `Stale` |
 | `Today Data Loaded Time` | Stamped on HTTP fetch only | Stamped on NVS load and HTTP fetch |
 | `Tomorrow Data Loaded Time` | `Never` after NVS boot load | Stamped on NVS load and HTTP fetch |
+| `Tomorrow Price Update Status Message` | *(various)* | `"No data yet"` on boot / after reboot (v1.2) |
+
+---
 
 ### HA entity ID changes
 
 All entity IDs changed due to the node name change from `entso-e-prices` to `eprices`.
 
-**Find and replace in all your automations and dashboards:**
+**Step 1 — bulk find and replace in all your automations and dashboards:**
 ```
 sensor.entso_e_prices_  →  sensor.eprices_
 button.entso_e_prices_  →  button.eprices_
 ```
 
-Then apply the individual sensor name slug changes from the tables above.
+**Step 2 — apply the individual sensor name slug renames** from the tables above
+for sensors whose names changed (not just the prefix).
+
+> **Tip:** After the bulk replace in Step 1, search for any remaining
+> `entso_e_prices_` strings to catch any that were missed.
 
 ### NVS data
 
 The NVS namespace changed from `entsoe2` to `eprices`. On first boot after
-flashing EPrices v1.0 the device will not find any stored data and will
+flashing EPrices the device will not find any stored data and will
 trigger a fresh HTTP fetch automatically. This is expected and safe.
 No manual NVS erase is required.
 
@@ -211,9 +236,10 @@ No manual NVS erase is required.
 ## Migration checklist
 
 - [ ] Flash `eprices.yaml` to the device
-- [ ] Update `secrets.yaml` — rename all `entsoe_` keys to `eprices_`; add `eprices_prov_fee` and `eprices_vat_rate`
-- [ ] In all HA automations: replace `entso_e_prices_` with `eprices_` in all entity IDs
-- [ ] Apply individual sensor name slug renames from the tables above
+- [ ] Update `secrets.yaml` — rename all `entsoe_` keys to `eprices_`; add `eprices_prov_fee`, `eprices_vat_rate`, and `eprices_neg_prov_fee`
+- [ ] In all HA automations: bulk replace `sensor.entso_e_prices_` → `sensor.eprices_` and `button.entso_e_prices_` → `button.eprices_`
+- [ ] Apply individual sensor slug renames from the tables above for sensors whose names changed
 - [ ] Remove any external HA automations that handled midnight bridge, boot recovery, or fetch scheduling — these are now all on-device
 - [ ] Verify the device fetches fresh data on first boot (check `Today NVS Status` and `Today Price Update Status Message`)
 - [ ] Update any HA dashboard cards referencing old entity IDs
+- [ ] Verify the JSON sensor entity IDs in dashboards — the `⁄` character slug may differ from expected; check against actual HA entity registry if needed

VERSION.md

@@ -1,5 +1,35 @@
 # EPrices – Version History
 
+## v1.2.1 — 2026-04-07
+
+Stability and housekeeping patch. No new sensors, no secrets changes,
+no entity ID changes. Drop-in replacement for v1.2.
+
+### ESP32 main task stack size increase
+
+Doubled the FreeRTOS main task stack from 8192 to 16384 bytes via
+`CONFIG_ESP_MAIN_TASK_STACK_SIZE`. Eliminates the stack overflow scenario
+most likely responsible for the spontaneous reboot observed in production
+on 2026-04-06 during a simultaneous NVS load + HTTP fetch/parse cycle.
+
+### Price vector heap pre-allocation at boot
+
+Added `.reserve(96)` on all four price vectors (`price_timestamps_today`,
+`price_values_today`, `price_timestamps_tomorrow`, `price_values_tomorrow`)
+in the `on_boot` lambda. Prevents repeated heap reallocation during NVS load
+and HTTP parse operations, reducing heap fragmentation and peak allocation
+pressure during the boot sequence.
+
+### Hourly JSON sensor cleared state unified
+
+`Today JSON Hourly Prices EUR⁄kWh` and `Tomorrow JSON Hourly Prices EUR⁄kWh`
+now publish `""` when cleared, matching the existing behaviour of all six
+15-minute JSON sensors. Previously they published `"[]"`.
+
+See `CHANGELOG.md` for full implementation details.
+
+---
+
 ## v1.2 — 2026-04-06
 
 ### HTTP fetch stuck-flag watchdog
@@ -25,8 +55,7 @@ sensor to undercount after the first scheduled attempt at 13:25.
 ### Status message improvements
 
 - `tomorrow_update_status_message` initial value changed from
-  `"Waiting for 13:20"` to `"No data yet"` — removes misleading time
-  reference shown after afternoon reboots
+  `"Waiting for 13:20"` to `"No data yet"`
 - `clear_tomorrow_prices` end message changed from
   `"Cleared – awaiting next 13:20 window"` to
   `"Cleared – awaiting fetch window"`

eprices.yaml

@@ -1,9 +1,20 @@
 # =============================================================================
-# ESPHome: EPrices v1.2
+# ESPHome: EPrices v1.2.1
 #
 # Electricity price data provided by Energy-Charts (https://energy-charts.info)
 # under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).
 #
+# v1.2.1 changes (2026-04-07):
+# - CONFIG_ESP_MAIN_TASK_STACK_SIZE raised from 8192 to 16384 bytes via
+#   esp32: framework: sdkconfig_options — eliminates stack overflow scenario
+#   observed in production during simultaneous NVS load + HTTP fetch/parse
+# - Price vectors pre-allocated at boot with .reserve(96) in on_boot lambda:
+#   price_timestamps_today, price_values_today,
+#   price_timestamps_tomorrow, price_values_tomorrow
+#   prevents repeated heap reallocation during NVS load and HTTP parse cycles
+# - Hourly JSON sensors now publish "" when cleared (was "[]") —
+#   consistent with all six 15-min JSON sensors
+#
 # v1.2 changes (2026-04-06):
 # - HTTP fetch stuck-flag watchdog (120 s) added to today and tomorrow workers:
 #   if is_updating_today / is_updating_tomorrow stays true for >120 s (TCP
@@ -86,11 +97,19 @@ esphome:
           } else {
             id(boot_time) = 0;
           }
+          // Pre-allocate price vectors to avoid repeated heap reallocation
+          // during NVS load and HTTP fetch/parse cycles
+          id(price_timestamps_today).reserve(96);
+          id(price_values_today).reserve(96);
+          id(price_timestamps_tomorrow).reserve(96);
+          id(price_values_tomorrow).reserve(96);
 
 esp32:
   board: esp32dev
   framework:
     type: esp-idf
+    sdkconfig_options:
+      CONFIG_ESP_MAIN_TASK_STACK_SIZE: "16384"
     # No include_builtin_idf_components needed — nvs headers are always
     # available in esp-idf framework; eprices_nvs.h includes them directly.
 
@@ -2103,7 +2122,7 @@ script:
           id(today_current_max_hourly_price_percentage).publish_state(NAN);
           id(last_update_success) = false;
           id(update_status_message) = "Cleared – awaiting NVS or HTTP";
-          id(json_hourly_prices_kwh).publish_state("[]");
+          id(json_hourly_prices_kwh).publish_state("");
           id(json_15min_prices_kwh_p1_00_00_07_45).publish_state("");
           id(json_15min_prices_kwh_p2_08_00_15_45).publish_state("");
           id(json_15min_prices_kwh_p3_16_00_23_45).publish_state("");
@@ -2136,7 +2155,7 @@ script:
           id(tomorrow_min_hourly_price).publish_state(NAN);
           id(tomorrow_max_hourly_price).publish_state(NAN);
           id(tomorrow_current_max_hourly_price_percentage).publish_state(NAN);
-          id(json_tomorrow_hourly_prices_kwh).publish_state("[]");
+          id(json_tomorrow_hourly_prices_kwh).publish_state("");
           id(json_tomorrow_15min_prices_kwh_p1_00_00_07_45).publish_state("");
           id(json_tomorrow_15min_prices_kwh_p2_08_00_15_45).publish_state("");
           id(json_tomorrow_15min_prices_kwh_p3_16_00_23_45).publish_state("");