Minor document changes for version 1.2.3

Updated Uptime description to include bucketed format and logbook entry frequency.

CHANGELOG.md

@@ -1,5 +1,158 @@
 # EPrices – Changelog
 
+## v1.2.3 — 2026-08-04
+
+### Uptime sensor bucket display and logbook change-detection
+
+The `Uptime` text sensor previously published a high-precision human-readable
+uptime string (e.g. `3 h 22 min`, `12 d 4 h 17 min`) on every internal
+`uptime` sensor update, which runs every 60 seconds. In the Home Assistant
+activity log, this produced one state change per minute during the first day
+after a reboot — a noisy stream redundant with the existing `Last Reboot`
+text sensor.
+
+The uptime lambda now formats the value into coarse hourly / daily / monthly
+buckets and only calls `publish_state` when the bucket string actually
+changes. Result: **one logbook entry per hour** for the first day, **one per
+day** through the first month, **one per month** through the first year, and
+**one per month** after that.
+
+**New display buckets:**
+
+| Boot age | State | Window |
+|---|---|---|
+| 0 – 59 min | `< 1 hour` | 1 h |
+| 1 – 23 h | `> N hour(s)` | 1 h |
+| 1 – 30 d | `> N day(s)` | 1 d |
+| 1 – 11 mo | `> N month(s)` | 30 d |
+| 12+ mo | `> N year(s)` or `> N year(s) N month(s)` | 30 d |
+
+Singular/plural is handled in C++ (`1 hour` vs `2 hours`, `1 day` vs
+`2 days`, etc.). Conventions: 1 month = 30 days, 1 year = 12 months —
+consistent with the existing `d / 30` month convention used elsewhere in
+the file.
+
+**New global:**
+- `last_published_uptime` (type: `std::string`, `restore_value: false`,
+  `initial_value: '""'`) — tracks the most recently published bucket value.
+  The uptime lambda compares against it and only calls `publish_state` when
+  the bucket string differs.
+
+The `update_interval: 60s` on the internal `uptime` sensor is kept as-is so
+the lambda still runs every minute and reliably catches hour-boundary
+transitions even under transient load.
+
+**Changed locations in `eprices.yaml`:**
+- `globals:` — added `last_published_uptime`
+- Internal `uptime` sensor `on_raw_value` lambda — replaced minute-precision
+  format with bucket display + change-detection guard
+
+---
+
+## 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

README.md

@@ -24,12 +24,16 @@ 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
 - Supports **any Energy-Charts bidding zone** (SI, DE-LU, AT, FR, HR, HU and more)
 - Full **diagnostic sensor suite** — NVS status, fetch attempts, API fetch times,
-  data loaded times, WiFi signal, human-readable uptime
+  data loaded times, WiFi signal, human-readable bucketed uptime (one HA logbook
+  entry per hour / day / month — no per-minute churn)
 - All fee and VAT settings configurable via `secrets.yaml` — **no code changes needed**
 
 ---
@@ -39,6 +43,12 @@ 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 +220,10 @@ 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 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 (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 (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 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; `""` 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; `""` 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; `""` 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 +250,10 @@ 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 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 (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 (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 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; `""` 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; `""` 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; `""` 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) |
@@ -256,7 +266,7 @@ safe on DST transition days (23-hour and 25-hour days).
 | Sensor | Entity ID | Description |
 |---|---|---|
 | Last Reboot | `sensor.eprices_last_reboot` | Timestamp of last device boot |
-| Uptime | `sensor.eprices_uptime` | Human-readable: `45 s` / `5 min` / `3 h 22 min` / `12 d 4 h` / `4 months 12 d` |
+| Uptime | `sensor.eprices_uptime` | Human-readable bucketed: `< 1 hour` / `> N hours` / `> N days` / `> N months` / `> N year(s) N month(s)` — one logbook entry per hour, day, or month |
 | WiFi Signal | `sensor.eprices_wifi_signal` | RSSI in dBm, updated every 60s |
 | Last Update Source | `sensor.eprices_last_update_source` | `NVS_boot` / `HTTP_today` / `midnight_bridge` / `NVS_api` etc. |
 | Today Data Date | `sensor.eprices_today_data_date` | Date of currently stored today data |

VERSION.md

@@ -1,5 +1,79 @@
 # EPrices – Version History
 
+## v1.2.3 — 2026-08-04
+
+Quietness patch for the Home Assistant activity log. No new sensors, no
+secrets changes, no entity ID changes. Drop-in replacement for v1.2.2.
+
+### Uptime display bucketed and change-detected
+
+The `Uptime` text sensor previously published a new value every minute
+(e.g. `3 h 22 min`, `12 d 4 h 17 min`) because the underlying internal
+`uptime` sensor updates every 60 seconds and the lambda always called
+`publish_state`. In the HA activity log this produced a noisy stream of
+state changes redundant with the existing `Last Reboot` text sensor.
+
+The lambda now formats uptime into coarse buckets and only publishes when
+the bucket string changes — **one logbook entry per hour** for the first
+day, then **one per day**, then **one per month**.
+
+**Buckets:**
+
+| Age | Display |
+|---|---|
+| 0 – 59 min | `< 1 hour` |
+| 1 – 23 h | `> 1 hour` ... `> 23 hours` |
+| 1 – 30 d | `> 1 day` ... `> 30 days` |
+| 1 – 11 mo | `> 1 month` ... `> 11 months` |
+| 12+ mo | `> 1 year` ... `> N year(s) N month(s)` |
+
+**New global:** `last_published_uptime` (`std::string`) — tracks the last
+published bucket so the lambda can skip publishing when the value hasn't
+crossed a boundary.
+
+See `CHANGELOG.md` for full implementation details.
+
+---
+
+## 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,

eprices.yaml

@@ -1,9 +1,38 @@
 # =============================================================================
-# ESPHome: EPrices v1.2.1
+# ESPHome: EPrices v1.2.3
 #
 # Electricity price data provided by Energy-Charts (https://energy-charts.info)
 # under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).
 #
+# v1.2.3 uptime log noise reduction (2026-08-04):
+# - Uptime text sensor now uses coarse bucketed display instead of minute
+#   precision: "< 1 hour" / "> N hour(s)" / "> N day(s)" / "> N month(s)" /
+#   "> N year(s)" / "> N year(s) N month(s)"
+#   Buckets update once per hour (first day), once per day (first month),
+#   once per month (first year) — eliminates per-minute state churn in
+#   the HA activity log
+# - Added global last_published_uptime (std::string) to track the last
+#   published bucket value; the uptime lambda only calls publish_state
+#   when the bucket string actually changes
+# - Singular/plural handled in C++ (1 hour vs 2 hours, 1 day vs 2 days, etc.)
+# - Conventions: 1 month = 30 days, 1 year = 12 months — consistent with
+#   the existing d / 30 month convention used elsewhere in the file
+#
+# 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
@@ -103,6 +132,8 @@ esphome:
           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
@@ -110,6 +141,12 @@ esp32:
     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.
 
@@ -486,6 +523,10 @@ globals:
   - id: boot_time
     type: time_t
     initial_value: '0'
+  - id: last_published_uptime
+    type: std::string
+    restore_value: false
+    initial_value: '""'
   - id: last_successful_update
     type: time_t
     initial_value: '0'
@@ -841,27 +882,44 @@ sensor:
       then:
         - lambda: |-
             uint32_t s = (uint32_t)x;
-            char buf[32];
-            if (s < 120) {
-              snprintf(buf, sizeof(buf), "%u s", s);
-            } else if (s < 48 * 3600) {
+            char buf[48];
+
+            if (s < 3600) {
+              // < 1 hour: one state, no logbook churn
+              snprintf(buf, sizeof(buf), "< 1 hour");
+            } else if (s < 86400UL) {
+              // 1..23 hours — bucket by full hour
               uint32_t h = s / 3600;
-              uint32_t m = (s % 3600) / 60;
-              if (h < 2)
-                snprintf(buf, sizeof(buf), "%u min", s / 60);
-              else
-                snprintf(buf, sizeof(buf), "%u h %u min", h, m);
-            } else if (s < 90UL * 86400UL) {
-              uint32_t d = s / 86400;
-              uint32_t h = (s % 86400) / 3600;
-              snprintf(buf, sizeof(buf), "%u d %u h", d, h);
+              snprintf(buf, sizeof(buf), "> %lu hour%s", h, h == 1 ? "" : "s");
+            } else if (s < 31UL * 86400UL) {
+              // 1..30 days — bucket by full day
+              uint32_t d = s / 86400UL;
+              snprintf(buf, sizeof(buf), "> %lu day%s", d, d == 1 ? "" : "s");
+            } else if (s < 12UL * 30UL * 86400UL) {
+              // 1..11 months — bucket by full month (1 month = 30 days)
+              uint32_t mo = s / (30UL * 86400UL);
+              snprintf(buf, sizeof(buf), "> %lu month%s", mo, mo == 1 ? "" : "s");
             } else {
-              uint32_t d   = s / 86400;
-              uint32_t mo  = d / 30;
-              uint32_t rem = d % 30;
-              snprintf(buf, sizeof(buf), "%u months %u d", mo, rem);
+              // 1 year and up — year + optional months (1 year = 12 months)
+              uint32_t mo_total = s / (30UL * 86400UL);
+              uint32_t y  = mo_total / 12;
+              uint32_t mo = mo_total % 12;
+              if (mo == 0) {
+                snprintf(buf, sizeof(buf), "> %lu year%s", y, y == 1 ? "" : "s");
+              } else {
+                snprintf(buf, sizeof(buf), "> %lu year%s %lu month%s",
+                         y, y == 1 ? "" : "s",
+                         mo, mo == 1 ? "" : "s");
+              }
+            }
+
+            // Only publish on actual bucket change — prevents
+            // per-minute state churn in HA's activity log
+            std::string new_state(buf);
+            if (new_state != id(last_published_uptime)) {
+              id(last_published_uptime) = new_state;
+              id(uptime_text).publish_state(new_state);
             }
-            id(uptime_text).publish_state(buf);
 
 # =============================================================================
 # TEXT SENSORS – TODAY
@@ -1364,15 +1422,22 @@ 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;
@@ -1417,6 +1482,9 @@ 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;
@@ -1428,13 +1496,17 @@ 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",
-                   id(today_entry_count), today_buf);
+          // v1.2.2: Log heap after parsing
+          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
@@ -1471,15 +1543,23 @@ 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;
@@ -1505,6 +1585,9 @@ 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;
@@ -1516,16 +1599,21 @@ 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",
-                   id(tomorrow_entry_count), tmr_buf);
+          // v1.2.2: Log heap after parsing
+          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:
@@ -1533,6 +1621,9 @@ 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.
@@ -1566,47 +1657,73 @@ 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_buf[json_h_len++] = ',';
             }
-            if (i < 23) json_h += ",";
           }
-          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 {
-            std::string j = "[";
+          // v1.2.2: Optimized build32 using fixed buffer approach
+          // 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]);
-                j += pb;
+                  len += snprintf(buf + len, sizeof(buf) - len, "%.4f", v[i]);
               } else {
-                j += "null";
+                len += snprintf(buf + len, sizeof(buf) - len, "null");
               }
-              if (i < start + 31) j += ",";
+              if (i < start + 31) {
+                buf[len++] = ',';
+              }
+              // Safety: prevent buffer overflow
+              if (len >= (int)sizeof(buf) - 20) break;
             }
-            j += "]"; return j;
+            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));
-          id(json_15min_prices_kwh_p3_16_00_23_45).publish_state(build32(64));
+
+          build32_fixed(0,  id(json_15min_prices_kwh_p1_00_00_07_45));
+          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);
@@ -1642,8 +1759,12 @@ 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:
@@ -1651,6 +1772,9 @@ 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++) {
@@ -1681,47 +1805,68 @@ 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_buf[json_h_len++] = ',';
             }
-            if (i < 23) json_h += ",";
           }
-          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 {
-            std::string j = "[";
+          // v1.2.2: Optimized build32 using fixed buffer approach
+          // 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]);
-                j += pb;
+                  len += snprintf(buf + len, sizeof(buf) - len, "%.4f", v[i]);
               } else {
-                j += "null";
+                len += snprintf(buf + len, sizeof(buf) - len, "null");
               }
-              if (i < start + 31) j += ",";
+              if (i < start + 31) {
+                buf[len++] = ',';
+              }
+              // Safety: prevent buffer overflow
+              if (len >= (int)sizeof(buf) - 20) break;
             }
-            j += "]"; return j;
+            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));
-          id(json_tomorrow_15min_prices_kwh_p3_16_00_23_45).publish_state(build32(64));
+
+          build32_fixed(0,  id(json_tomorrow_15min_prices_kwh_p1_00_00_07_45));
+          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);
@@ -1752,6 +1897,9 @@ 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
   # ---------------------------------------------------------------------------