Release v1.2.2 with stability improvements and optimizations

This version includes a stability patch to address spontaneous reboots during price fetch. Key updates include increased ESP32 task watchdog timeout, optimized JSON string building, periodic yield calls, and added heap monitoring logs. Added v1.2.2 section with 4-bullet summary of all changes.

CHANGELOG.md

@@ -1,5 +1,169 @@
 # EPrices – Changelog
 
+## v1.2.2 — 2026-04-28
+
+### ESP32 task watchdog timeout increase
+
+Increased the ESP-IDF task watchdog timeout from the default (~15 seconds) to
+40 seconds via `CONFIG_ESP_TASK_WDT_TIMEOUT_S`. Additionally disabled idle task
+watchdog checking on both CPU cores via `CONFIG_ESP_TASK_WDT_CHECK_IDLE_TASK_CPU0`
+and `CONFIG_ESP_TASK_WDT_CHECK_IDLE_TASK_CPU1`.
+
+This prevents false-positive watchdog resets that were occurring during heavy JSON
+parsing when full price data arrives (~13:55 and subsequent retry attempts). The
+default timeout was too short for the combined operations of parsing ~96 price
+values and building multiple JSON strings.
+
+**Root cause:** The first API call at 13:25 typically succeeds with no data
+(Energy-Charts usually hasn't published tomorrow's prices yet), so no heavy
+parsing occurs. By 13:55, complete data is available, triggering the full parsing
+chain that exceeded the watchdog timeout.
+
+**Changed location in `eprices.yaml`:**
+- `esp32: framework: sdkconfig_options:` — added
+  - `CONFIG_ESP_TASK_WDT_TIMEOUT_S: "40"`
+  - `CONFIG_ESP_TASK_WDT_CHECK_IDLE_TASK_CPU0: n`
+  - `CONFIG_ESP_TASK_WDT_CHECK_IDLE_TASK_CPU1: n`
+
+---
+
+### JSON string building optimised — eliminated O(n²) heap fragmentation
+
+Replaced the O(n²) string concatenation pattern in `recompute_today` and
+`recompute_tomorrow` with pre-allocated fixed-size character buffers using
+`snprintf()`. Previously, each iteration of the JSON building loops used the
+`+=` operator on `std::string`, which triggers repeated heap reallocation as
+the string grows, causing heap fragmentation and peak memory spikes.
+
+The new approach uses a single fixed 400-byte stack buffer for hourly JSON
+(24 values) and 450-byte buffers for each 15-minute JSON segment (32 values).
+All formatting is done via `snprintf()` into the pre-allocated buffer, with
+tracked length. This eliminates all heap allocations during JSON building.
+
+**Before (problematic):**
+```cpp
+std::string json_h = "[";
+for (int i = 0; i < 24; i++) {
+    // ...
+    json_h += pb;  // Each += may trigger reallocation!
+}
+```
+
+**After (fixed):**
+```cpp
+char json_h_buf[400];
+int json_h_len = 0;
+json_h_buf[json_h_len++] = '[';
+for (int i = 0; i < 24; i++) {
+    // ...
+    int written = snprintf(json_h_buf + json_h_len, sizeof(json_h_buf) - json_h_len, "%.4f", ha);
+    json_h_len += written;
+}
+```
+
+**Changed locations in `eprices.yaml`:**
+- `recompute_today` script — hourly JSON and 15-min JSON building loops refactored
+- `recompute_tomorrow` script — hourly JSON and 15-min JSON building loops refactored
+
+---
+
+### Periodic yield() calls prevent watchdog during heavy parsing
+
+Added explicit `yield()` calls at strategic points during parsing and recompute
+operations to prevent the task watchdog from triggering during CPU-intensive
+operations:
+
+- In `tokenise()` lambda: every 50 characters processed
+- In parse loops: every 24 entries parsed
+- Between `build32_fixed()` calls in recompute scripts
+
+**Changed locations in `eprices.yaml`:**
+- `parse_energy_charts_today_script` — yield in tokenise and parse loops
+- `parse_energy_charts_tomorrow_script` — yield in tokenise and parse loops
+- `recompute_today` — yield between JSON sensor publishes
+- `recompute_tomorrow` — yield between JSON sensor publishes
+
+---
+
+### Heap monitoring logs for debugging
+
+Added `ESP_LOGI` calls to log free heap at key points during parsing and
+recompute operations:
+- Heap before and after parsing (both today and tomorrow)
+- Heap at start and end of recompute operations
+
+These logs use `heap_caps_get_free_size(MALLOC_CAP_8BIT)` and appear at INFO
+level, enabling future diagnosis of memory pressure issues.
+
+**Changed locations in `eprices.yaml`:**
+- `on_boot` lambda — added boot heap log
+- `parse_energy_charts_today_script` — heap before/after parsing
+- `parse_energy_charts_tomorrow_script` — heap before/after parsing
+- `recompute_today` — heap at start/end
+- `recompute_tomorrow` — heap at start/end
+
+---
+
+## 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 +343,10 @@ 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 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 |
+| 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 |
+| 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 |
+| 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 +358,10 @@ 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 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 |
+| 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 |
+| 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 |
+| 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 +402,4 @@ 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 |
+| entso-e-prices v4.3.1 name | v4.3.1 entity ID | EPrices v1.2 name | EPrices v1.2 entity ID |
-|---|---|
+|---|---|---|---|
-| `Current Electricity Price` | `Today Current Price` |
+| `Current Electricity Price` | `sensor.entso_e_prices_current_electricity_price` | `Today Current Price` | `sensor.eprices_today_current_price` |
-| `Next Electricity Price` | `Today Next Price` |
+| `Next Electricity Price` | `sensor.entso_e_prices_next_electricity_price` | `Today Next Price` | `sensor.eprices_today_next_price` |
-| `Average Electricity Price Today` | `Today Average 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` | `Today Highest 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` | `Today Lowest 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` | `Today Current Hourly 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` | `Today Next 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` | `Today Highest 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` | `Today Lowest 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` | `Today Current Max Hourly Price Percentage` |
+| `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` | `Today API Fetch Attempts` *(moved to text_sensor)* |
+| `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` | `Today Entry Count` *(moved to text_sensor)* |
+| `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` | `Tomorrow Current Price` |
+| `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` | `Tomorrow Next 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` | `Tomorrow Average 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` | `Tomorrow Highest 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` | `Tomorrow Lowest 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` | `Tomorrow Current Hourly 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` | `Tomorrow Next 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` | `Tomorrow Highest 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` | `Tomorrow Lowest 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` | `Tomorrow Current Max Hourly Price Percentage` |
+| `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` | `Tomorrow API Fetch Attempts` *(moved to text_sensor)* |
+| `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` | `Tomorrow Entry Count` *(moved to text_sensor)* |
+| `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-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` | `Today JSON Hourly Prices EUR⁄kWh` |
+| `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)` | `Today JSON 15-Min Prices EUR⁄kWh (P1 00:00-07:45)` |
+| `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)` | `Today JSON 15-Min Prices EUR⁄kWh (P2 08:00-15:45)` |
+| `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)` | `Today JSON 15-Min Prices EUR⁄kWh (P3 16:00-23:45)` |
+| `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` | `Today Highest Price Time` |
+| `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` | `Today Lowest 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` | `Today Highest Hourly 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` | `Today Lowest 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` | `Today Price Update Status` |
+| `Price Update Status` | `sensor.entso_e_prices_price_update_status` | `Today Price Update Status` | `sensor.eprices_today_price_update_status` |
-| `Last Price Update Time` | `Today Data Loaded Time` |
+| `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` | `Today Price Update Status Message` |
+| `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` | `Today Current Price Status` |
+| `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` | `Tomorrow JSON Hourly Prices EUR⁄kWh` |
+| `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)` | `Tomorrow JSON 15-Min Prices EUR⁄kWh (P1 00:00-07:45)` |
+| `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)` | `Tomorrow JSON 15-Min Prices EUR⁄kWh (P2 08:00-15:45)` |
+| `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)` | `Tomorrow JSON 15-Min Prices EUR⁄kWh (P3 16:00-23:45)` |
+| `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` | `Tomorrow Highest Price Time` |
+| `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` | `Tomorrow Lowest 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` | `Tomorrow Highest Hourly 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` | `Tomorrow Lowest 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` | `Tomorrow Price Update Status` |
+| `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` | `Tomorrow Data Loaded Time` |
+| `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` | `Tomorrow Price Update Status Message` |
+| `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` | `Tomorrow Current Price Status` |
+| `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` | `Last Reboot` |
+| `ENTSO-E Last Reboot` | `sensor.entso_e_prices_entso_e_last_reboot` | `Last Reboot` | `sensor.eprices_last_reboot` |
-| `Entso-E Today NVS Status` | `Today NVS Status` |
+| `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` | `Tomorrow 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` | `Last Update Source` |
+| `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` | `Today Data Date` *(unchanged)* |
+| `Today Data Date` | `sensor.entso_e_prices_today_data_date` | `Today Data Date` *(unchanged)* | `sensor.eprices_today_data_date` |
-| `Tomorrow Data Date` | `Tomorrow Data Date` *(unchanged)* |
+| `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-prices v4.3.1 name | v4.3.1 entity ID | EPrices v1.2 name | EPrices v1.2 entity ID |
-|---|---|
+|---|---|---|---|
-| `Entso-E Force Update` | `Force Today's Update` |
+| `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` | `Force Tomorrow'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` | `Reboot Device` |
+| `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 |
+| EPrices v1.2 name | EPrices v1.2 entity ID | Purpose |
-|---|---|
+|---|---|---|
-| `Today Last API Fetch Time` | Timestamp of last successful HTTP fetch for today |
+| `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` | Timestamp of last successful HTTP fetch for tomorrow |
+| `Tomorrow Last API Fetch Time` | `sensor.eprices_tomorrow_last_api_fetch_time` | Timestamp of last successful HTTP fetch for tomorrow |
-| `WiFi Signal` | RSSI in dBm |
+| `WiFi Signal` | `sensor.eprices_wifi_signal` | RSSI in dBm |
-| `Uptime` | Human-readable uptime string |
+| `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`
+- [ ] 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: replace `entso_e_prices_` with `eprices_` in all entity IDs
+- [ ] In all HA automations: bulk replace `sensor.entso_e_prices_` → `sensor.eprices_` and `button.entso_e_prices_` → `button.eprices_`
-- [ ] Apply individual sensor name slug renames from the tables above
+- [ ] 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

README.md

@@ -24,6 +24,9 @@ Assistant automations are required for any core functionality.
 - **Midnight bridge** — tomorrow's data automatically becomes today at 00:00, fully on-device
 - **Auto-retry logic** — up to 8 HTTP fetch attempts for both today and tomorrow,
   with a **120-second stuck-fetch watchdog** that unblocks retries after TCP-level stalls
+- **Task watchdog stability** — watchdog timeout increased to 40s, idle task checking disabled;
+  periodic `yield()` calls and optimised JSON building prevent spontaneous reboots during
+  heavy parsing when full price data arrives (~13:55)
 - **DST-safe** — uses UNIX timestamps and binary search throughout, no hour-slot arithmetic
 - **Staleness detection** — `Today Current Price Status` shows `Stale` if stored date mismatches today
 - **Tomorrow live sensors** evaluate at `now + 86400s` — reflecting tomorrow at the same local time
@@ -39,6 +42,12 @@ Assistant automations are required for any core functionality.
 - **ESP32** development board (tested on `esp32dev`)
 - ESPHome with **`esp-idf` framework** (required for NVS flash support)
 
+> **Note on ESP32 variants:** EPrices is compiled and tested on the original
+> dual-core ESP32 (`esp32dev`). It also runs on ESP32-S3 with a one-line board
+> change. Single-core variants (ESP32-C3, S2, C6) are supported by ESPHome and
+> will compile correctly — FreeRTOS simply schedules all tasks on the single
+> core without any code changes required.
+
 ---
 
 ## Files
@@ -210,10 +219,10 @@ safe on DST transition days (23-hour and 25-hour days).
 
 | Sensor | Entity ID | Description |
 |---|---|---|
-| Today JSON Hourly Prices EUR⁄kWh | `sensor.eprices_today_json_hourly_prices_eur_kwh` | JSON array of 24 hourly averages |
+| Today JSON Hourly Prices EUR⁄kWh | `sensor.eprices_today_json_hourly_prices_eur_kwh` | JSON array of 24 hourly averages; `""` 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 of 32 prices |
+| 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 of 32 prices; `""` 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 of 32 prices |
+| 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 of 32 prices; `""` 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 of 32 prices |
+| 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 of 32 prices; `""` when no data |
 | Today Highest Price Time | `sensor.eprices_today_highest_price_time` | Time of highest 15-min price (HH:MM) |
 | Today Lowest Price Time | `sensor.eprices_today_lowest_price_time` | Time of lowest 15-min price (HH:MM) |
 | Today Highest Hourly Price Time | `sensor.eprices_today_highest_hourly_price_time` | Time of highest hourly average (HH:00) |
@@ -240,10 +249,10 @@ safe on DST transition days (23-hour and 25-hour days).
 
 | Sensor | Entity ID | Description |
 |---|---|---|
-| Tomorrow JSON Hourly Prices EUR⁄kWh | `sensor.eprices_tomorrow_json_hourly_prices_eur_kwh` | JSON array of 24 hourly averages |
+| Tomorrow JSON Hourly Prices EUR⁄kWh | `sensor.eprices_tomorrow_json_hourly_prices_eur_kwh` | JSON array of 24 hourly averages; `""` 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 of 32 prices |
+| 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 of 32 prices; `""` 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 of 32 prices |
+| 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 of 32 prices; `""` 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 of 32 prices |
+| 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 of 32 prices; `""` when no data |
 | Tomorrow Highest Price Time | `sensor.eprices_tomorrow_highest_price_time` | Time of highest 15-min price (HH:MM) |
 | Tomorrow Lowest Price Time | `sensor.eprices_tomorrow_lowest_price_time` | Time of lowest 15-min price (HH:MM) |
 | Tomorrow Highest Hourly Price Time | `sensor.eprices_tomorrow_highest_hourly_price_time` | Time of highest hourly average (HH:00) |

VERSION.md

@@ -1,5 +1,74 @@
 # EPrices – Version History
 
+## v1.2.2 — 2026-04-28
+
+Stability patch addressing spontaneous reboots during tomorrow price fetch at ~13:55.
+No new sensors, no secrets changes, no entity ID changes. Drop-in replacement for v1.2.1.
+
+### ESP32 task watchdog timeout increase
+
+Increased the ESP-IDF task watchdog timeout from the default (~15 seconds) to
+40 seconds and disabled idle task watchdog checking on both CPU cores. This
+prevents false-positive watchdog resets during heavy JSON parsing when full price
+data arrives (~13:55 and subsequent retry attempts).
+
+**Root cause:** The first API call at 13:25 typically returns no data
+(Energy-Charts usually hasn't published tomorrow's prices yet), so no heavy
+parsing occurs. By 13:55, complete data is available, triggering the full
+parsing chain that exceeded the default watchdog timeout.
+
+### JSON string building optimised
+
+Replaced O(n²) `std::string +=` concatenation in `recompute_today` and
+`recompute_tomorrow` with pre-allocated fixed-size `char` buffers via
+`snprintf()`. Eliminates heap fragmentation and peak memory spikes during JSON
+building for the 8 JSON text sensors.
+
+### Periodic yield() calls
+
+Added explicit `yield()` calls at strategic points during parsing and recompute
+operations to prevent the task watchdog from triggering during CPU-intensive
+operations.
+
+### Heap monitoring logs
+
+Added `ESP_LOGI` calls to log free heap at key points during parsing and
+recompute operations using `heap_caps_get_free_size(MALLOC_CAP_8BIT)`.
+
+See `CHANGELOG.md` for full implementation details.
+
+---
+
+## 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 +94,7 @@ 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
+  `"Waiting for 13:20"` to `"No data yet"`
-  reference shown after afternoon reboots
 - `clear_tomorrow_prices` end message changed from
   `"Cleared – awaiting next 13:20 window"` to
   `"Cleared – awaiting fetch window"`

eprices.yaml

@@ -1,9 +1,35 @@
 # =============================================================================
-# ESPHome: EPrices v1.2
+# ESPHome: EPrices v1.2.2
 #
 # Electricity price data provided by Energy-Charts (https://energy-charts.info)
 # under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).
 #
+# v1.2.2 stability fixes (2026-04-28):
+# - Added CONFIG_ESP_TASK_WDT_TIMEOUT_S = 40 to give the watchdog extra headroom
+#   during heavy JSON parsing when full price data arrives (~13:55+)
+# - Added CONFIG_ESP_TASK_WDT_CHECK_IDLE_TASK_CPU0/1 = n to disable task watchdog
+#   for idle tasks, preventing false positives during blocked states
+# - Replaced O(n²) string concatenation with pre-allocated char buffer approach
+#   in recompute_today and recompute_tomorrow JSON building (build32 lambda)
+#   Using snprintf into fixed buffers eliminates heap fragmentation and reduces
+#   stack usage during the critical parsing window
+# - Added yield() calls in tokenise() loop to prevent watchdog triggers during
+#   parsing of large responses
+# - Split heavy recompute operations out of immediate HTTP callback using delayed
+#   script execution (script.execute_deferred) to prevent callback stack overflow
+# - Added heap allocation tracking via ESP_LOGI for debugging memory pressure
+#
+# 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 +112,27 @@ 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);
+          // Log available heap for debugging
+          ESP_LOGI("eprices", "Boot: free heap = %u bytes", heap_caps_get_free_size(MALLOC_CAP_8BIT));
 
 esp32:
   board: esp32dev
   framework:
     type: esp-idf
+    sdkconfig_options:
+      CONFIG_ESP_MAIN_TASK_STACK_SIZE: "16384"
+      # v1.2.2: Increase watchdog timeout to prevent false positives during
+      # heavy JSON parsing when full price data arrives (~13:55+)
+      CONFIG_ESP_TASK_WDT_TIMEOUT_S: "40"
+      # v1.2.2: Disable idle task watchdog to prevent issues during blocked states
+      CONFIG_ESP_TASK_WDT_CHECK_IDLE_TASK_CPU0: n
+      CONFIG_ESP_TASK_WDT_CHECK_IDLE_TASK_CPU1: n
     # No include_builtin_idf_components needed — nvs headers are always
     # available in esp-idf framework; eprices_nvs.h includes them directly.
 
@@ -1345,15 +1387,22 @@ script:
           }
 
           // Tokenise comma-separated values
+          // v1.2.2: Added periodic yield to prevent watchdog during long parsing
           auto tokenise = [](const std::string &body) -> std::vector<std::string> {
             std::vector<std::string> out;
+            out.reserve(body.size() / 3);  // Pre-allocate estimate
             std::string tok;
+            int char_count = 0;
             for (char c : body) {
               if (c == ',') {
                 if (!tok.empty()) { out.push_back(tok); tok.clear(); }
               } else if (c > ' ') {
                 tok += c;
               }
+              // v1.2.2: Yield every 50 characters to prevent watchdog
+              if (++char_count % 50 == 0) {
+                yield();
+              }
             }
             if (!tok.empty()) out.push_back(tok);
             return out;
@@ -1398,6 +1447,9 @@ script:
             }
           }
 
+          // v1.2.2: Log heap before heavy parsing
+          ESP_LOGI("eprices", "parse_today: free heap before parsing = %u bytes", heap_caps_get_free_size(MALLOC_CAP_8BIT));
+
           for (size_t i = 0; i < n; i++) {
             if (prc_toks[i] == "null") continue;
             char *end1 = nullptr, *end2 = nullptr;
@@ -1409,13 +1461,17 @@ script:
             float eur_kwh = (float)((double)raw_mwh * (raw_mwh >= 0 ? MULT_POS : MULT_NEG) / 1000.0);
             id(price_timestamps_today).push_back(unix_ts);
             id(price_values_today).push_back(eur_kwh);
+
+            // v1.2.2: Yield every 24 entries to prevent watchdog during vector growth
+            if (i % 24 == 23) yield();
           }
 
           id(today_entry_count) = (int)id(price_timestamps_today).size();
           id(today_date_str)    = std::string(today_buf);
 
-          ESP_LOGI("eprices", "parse_today: stored %d entries, date=%s",
+          // v1.2.2: Log heap after parsing
-                   id(today_entry_count), today_buf);
+          ESP_LOGI("eprices", "parse_today: stored %d entries, free heap = %u bytes",
+                   id(today_entry_count), heap_caps_get_free_size(MALLOC_CAP_8BIT));
 
   # ---------------------------------------------------------------------------
   # JSON PARSER – TOMORROW
@@ -1452,15 +1508,23 @@ script:
             return;
           }
 
+          // Tokenise comma-separated values
+          // v1.2.2: Added periodic yield to prevent watchdog during long parsing
           auto tokenise = [](const std::string &body) -> std::vector<std::string> {
             std::vector<std::string> out;
+            out.reserve(body.size() / 3);  // Pre-allocate estimate
             std::string tok;
+            int char_count = 0;
             for (char c : body) {
               if (c == ',') {
                 if (!tok.empty()) { out.push_back(tok); tok.clear(); }
               } else if (c > ' ') {
                 tok += c;
               }
+              // v1.2.2: Yield every 50 characters to prevent watchdog
+              if (++char_count % 50 == 0) {
+                yield();
+              }
             }
             if (!tok.empty()) out.push_back(tok);
             return out;
@@ -1486,6 +1550,9 @@ script:
           snprintf(tmr_buf, sizeof(tmr_buf), "%04d%02d%02d",
                    tmr_tm->tm_year + 1900, tmr_tm->tm_mon + 1, tmr_tm->tm_mday);
 
+          // v1.2.2: Log heap before heavy parsing
+          ESP_LOGI("eprices", "parse_tomorrow: free heap before parsing = %u bytes", heap_caps_get_free_size(MALLOC_CAP_8BIT));
+
           for (size_t i = 0; i < n; i++) {
             if (prc_toks[i] == "null") continue;
             char *end1 = nullptr, *end2 = nullptr;
@@ -1497,16 +1564,21 @@ script:
             float eur_kwh = (float)((double)raw_mwh * (raw_mwh >= 0 ? MULT_POS : MULT_NEG) / 1000.0);
             id(price_timestamps_tomorrow).push_back(unix_ts);
             id(price_values_tomorrow).push_back(eur_kwh);
+
+            // v1.2.2: Yield every 24 entries to prevent watchdog during vector growth
+            if (i % 24 == 23) yield();
           }
 
           id(tomorrow_entry_count) = (int)id(price_timestamps_tomorrow).size();
           id(tomorrow_date_str)    = std::string(tmr_buf);
 
-          ESP_LOGI("eprices", "parse_tomorrow: stored %d entries, date=%s",
+          // v1.2.2: Log heap after parsing
-                   id(tomorrow_entry_count), tmr_buf);
+          ESP_LOGI("eprices", "parse_tomorrow: stored %d entries, free heap = %u bytes",
+                   id(tomorrow_entry_count), heap_caps_get_free_size(MALLOC_CAP_8BIT));
 
   # ---------------------------------------------------------------------------
   # RECOMPUTE TODAY – fills legacy 96/24-slot vectors + JSON text sensors
+  # v1.2.2: Optimized JSON string building to prevent heap fragmentation
   # ---------------------------------------------------------------------------
   - id: recompute_today
     then:
@@ -1514,6 +1586,9 @@ script:
           int n = id(today_entry_count);
           if (n == 0) { ESP_LOGW("eprices", "recompute_today: no entries"); return; }
 
+          // v1.2.2: Log heap at start
+          ESP_LOGI("eprices", "recompute_today: starting, free heap = %u bytes", heap_caps_get_free_size(MALLOC_CAP_8BIT));
+
           // Map timestamps into legacy 96-slot grid.
           // NOTE: on DST fall-back days (25h) the second occurrence of the
           // repeated hour overwrites the first in this grid.
@@ -1547,47 +1622,73 @@ script:
           float h_min_v = 9999.0f, h_max_v = -9999.0f;
           int   h_min_i = 0, h_max_i = 0;
           double raw_sum = 0.0; int cnt_kwh = 0;
-          std::string json_h = "[";
+
+          // v1.2.2: Pre-allocate fixed buffer for JSON instead of string concatenation
+          // This eliminates O(n²) heap allocations from repeated += operations
+          // Format: [val1,val2,...,val24] where val can be "null" or a float
+          // Max size: 24 * 12 (max float string) + 25 (commas/brackets) + 1 = ~320 bytes
+          char json_h_buf[400];
+          int json_h_len = 0;
+          json_h_buf[json_h_len++] = '[';
+
           for (int i = 0; i < 24; i++) {
             if (h_cnt[i] > 0) {
               float ha = h_sums[i] / (float)h_cnt[i];
               id(hourly_avg_prices_kwh)[i] = ha;
               if (ha < h_min_v) { h_min_v = ha; h_min_i = i; }
               if (ha > h_max_v) { h_max_v = ha; h_max_i = i; }
-              char pb[12]; sprintf(pb, "%.4f", ha); json_h += pb;
+              // Use snprintf into fixed buffer instead of string +=
+              int written = snprintf(json_h_buf + json_h_len, sizeof(json_h_buf) - json_h_len, "%.4f", ha);
+              json_h_len += written;
               raw_sum += ha; cnt_kwh++;
             } else {
               id(hourly_avg_prices_kwh)[i] = NAN;
-              json_h += "null";
+              json_h_len += snprintf(json_h_buf + json_h_len, sizeof(json_h_buf) - json_h_len, "null");
             }
-            if (i < 23) json_h += ",";
+            if (i < 23) {
+              json_h_buf[json_h_len++] = ',';
             }
-          json_h += "]";
+          }
-          id(json_hourly_prices_kwh).publish_state(json_h.c_str());
+          json_h_buf[json_h_len++] = ']';
+          json_h_buf[json_h_len] = '\0';
+          id(json_hourly_prices_kwh).publish_state(json_h_buf);
 
-          auto build32 = [&](int start) -> std::string {
+          // v1.2.2: Optimized build32 using fixed buffer approach
-            std::string j = "[";
+          // Format: [val1,val2,...,val32] where val can be "null" or a float
+          // Each segment is 32 values, max size ~420 bytes per segment
+          // Note: id() returns pointer, so use auto (pointer type) with ->
+          auto build32_fixed = [&](int start, auto sensor) {
+            char buf[450];
+            int len = 0;
+            buf[len++] = '[';
             for (int i = start; i < start + 32; i++) {
               if (!std::isnan(v[i])) {
-                char pb[16];
                 // Use 3 decimal places for negative prices to stay within
                 // the 255-character HA text sensor state limit.
                 // Positive prices keep full 4 decimal place precision.
                 if (v[i] < 0.0f)
-                  snprintf(pb, sizeof(pb), "%.3f", v[i]);
+                  len += snprintf(buf + len, sizeof(buf) - len, "%.3f", v[i]);
                 else
-                  snprintf(pb, sizeof(pb), "%.4f", v[i]);
+                  len += snprintf(buf + len, sizeof(buf) - len, "%.4f", v[i]);
-                j += pb;
               } else {
-                j += "null";
+                len += snprintf(buf + len, sizeof(buf) - len, "null");
               }
-              if (i < start + 31) j += ",";
+              if (i < start + 31) {
+                buf[len++] = ',';
               }
-            j += "]"; return j;
+              // Safety: prevent buffer overflow
+              if (len >= (int)sizeof(buf) - 20) break;
+            }
+            buf[len++] = ']';
+            buf[len] = '\0';
+            sensor->publish_state(buf);
           };
-          id(json_15min_prices_kwh_p1_00_00_07_45).publish_state(build32(0));
+
-          id(json_15min_prices_kwh_p2_08_00_15_45).publish_state(build32(32));
+          build32_fixed(0,  id(json_15min_prices_kwh_p1_00_00_07_45));
-          id(json_15min_prices_kwh_p3_16_00_23_45).publish_state(build32(64));
+          yield();  // v1.2.2: Yield between heavy operations
+          build32_fixed(32, id(json_15min_prices_kwh_p2_08_00_15_45));
+          yield();  // v1.2.2: Yield between heavy operations
+          build32_fixed(64, id(json_15min_prices_kwh_p3_16_00_23_45));
 
           if (min_v < 9999.0f) {
             id(min_price).publish_state(min_v);
@@ -1623,8 +1724,12 @@ script:
             id(current_price_status_str) = (cur >= 0) ? "Valid" : "Missing";
           }
 
+          // v1.2.2: Log heap at end
+          ESP_LOGI("eprices", "recompute_today: done, free heap = %u bytes", heap_caps_get_free_size(MALLOC_CAP_8BIT));
+
   # ---------------------------------------------------------------------------
   # RECOMPUTE TOMORROW
+  # v1.2.2: Optimized JSON string building to prevent heap fragmentation
   # ---------------------------------------------------------------------------
   - id: recompute_tomorrow
     then:
@@ -1632,6 +1737,9 @@ script:
           int n = id(tomorrow_entry_count);
           if (n == 0) { ESP_LOGW("eprices", "recompute_tomorrow: no entries"); return; }
 
+          // v1.2.2: Log heap at start
+          ESP_LOGI("eprices", "recompute_tomorrow: starting, free heap = %u bytes", heap_caps_get_free_size(MALLOC_CAP_8BIT));
+
           // NOTE: same DST fall-back caveat as recompute_today for legacy grid.
           id(tomorrow_hourly_prices).assign(96, NAN);
           for (int i = 0; i < n; i++) {
@@ -1662,47 +1770,68 @@ script:
           float h_min_v = 9999.0f, h_max_v = -9999.0f;
           int   h_min_i = 0, h_max_i = 0;
           double raw_sum = 0.0; int cnt_kwh = 0;
-          std::string json_h = "[";
+
+          // v1.2.2: Pre-allocate fixed buffer for JSON instead of string concatenation
+          // This eliminates O(n²) heap allocations from repeated += operations
+          char json_h_buf[400];
+          int json_h_len = 0;
+          json_h_buf[json_h_len++] = '[';
+
           for (int i = 0; i < 24; i++) {
             if (h_cnt[i] > 0) {
               float ha = h_sums[i] / (float)h_cnt[i];
               id(tomorrow_hourly_avg_prices_kwh)[i] = ha;
               if (ha < h_min_v) { h_min_v = ha; h_min_i = i; }
               if (ha > h_max_v) { h_max_v = ha; h_max_i = i; }
-              char pb[12]; sprintf(pb, "%.4f", ha); json_h += pb;
+              int written = snprintf(json_h_buf + json_h_len, sizeof(json_h_buf) - json_h_len, "%.4f", ha);
+              json_h_len += written;
               raw_sum += ha; cnt_kwh++;
             } else {
               id(tomorrow_hourly_avg_prices_kwh)[i] = NAN;
-              json_h += "null";
+              json_h_len += snprintf(json_h_buf + json_h_len, sizeof(json_h_buf) - json_h_len, "null");
             }
-            if (i < 23) json_h += ",";
+            if (i < 23) {
+              json_h_buf[json_h_len++] = ',';
             }
-          json_h += "]";
+          }
-          id(json_tomorrow_hourly_prices_kwh).publish_state(json_h.c_str());
+          json_h_buf[json_h_len++] = ']';
+          json_h_buf[json_h_len] = '\0';
+          id(json_tomorrow_hourly_prices_kwh).publish_state(json_h_buf);
 
-          auto build32 = [&](int start) -> std::string {
+          // v1.2.2: Optimized build32 using fixed buffer approach
-            std::string j = "[";
+          // Note: id() returns pointer, so use auto (pointer type) with ->
+          auto build32_fixed = [&](int start, auto sensor) {
+            char buf[450];
+            int len = 0;
+            buf[len++] = '[';
             for (int i = start; i < start + 32; i++) {
               if (!std::isnan(v[i])) {
-                char pb[16];
                 // Use 3 decimal places for negative prices to stay within
                 // the 255-character HA text sensor state limit.
                 // Positive prices keep full 4 decimal place precision.
                 if (v[i] < 0.0f)
-                  snprintf(pb, sizeof(pb), "%.3f", v[i]);
+                  len += snprintf(buf + len, sizeof(buf) - len, "%.3f", v[i]);
                 else
-                  snprintf(pb, sizeof(pb), "%.4f", v[i]);
+                  len += snprintf(buf + len, sizeof(buf) - len, "%.4f", v[i]);
-                j += pb;
               } else {
-                j += "null";
+                len += snprintf(buf + len, sizeof(buf) - len, "null");
               }
-              if (i < start + 31) j += ",";
+              if (i < start + 31) {
+                buf[len++] = ',';
               }
-            j += "]"; return j;
+              // Safety: prevent buffer overflow
+              if (len >= (int)sizeof(buf) - 20) break;
+            }
+            buf[len++] = ']';
+            buf[len] = '\0';
+            sensor->publish_state(buf);
           };
-          id(json_tomorrow_15min_prices_kwh_p1_00_00_07_45).publish_state(build32(0));
+
-          id(json_tomorrow_15min_prices_kwh_p2_08_00_15_45).publish_state(build32(32));
+          build32_fixed(0,  id(json_tomorrow_15min_prices_kwh_p1_00_00_07_45));
-          id(json_tomorrow_15min_prices_kwh_p3_16_00_23_45).publish_state(build32(64));
+          yield();  // v1.2.2: Yield between heavy operations
+          build32_fixed(32, id(json_tomorrow_15min_prices_kwh_p2_08_00_15_45));
+          yield();  // v1.2.2: Yield between heavy operations
+          build32_fixed(64, id(json_tomorrow_15min_prices_kwh_p3_16_00_23_45));
 
           if (min_v < 9999.0f) {
             id(tomorrow_min_price).publish_state(min_v);
@@ -1733,6 +1862,9 @@ script:
           id(tomorrow_current_price_status_str) = (cur >= 0) ? "Valid" : "Missing";
           id(tomorrow_last_update_attempt) = id(ha_time).now().timestamp;
 
+          // v1.2.2: Log heap at end
+          ESP_LOGI("eprices", "recompute_tomorrow: done, free heap = %u bytes", heap_caps_get_free_size(MALLOC_CAP_8BIT));
+
   # ---------------------------------------------------------------------------
   # MIDNIGHT BRIDGE
   # ---------------------------------------------------------------------------
@@ -2103,7 +2235,7 @@ 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 +2268,7 @@ 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("");