Update CHANGELOG for v7.2 release

Document bug fixes and improvements for v7.2 release, including button responsiveness and screen control issues.

CHANGELOG.md

@@ -2,6 +2,532 @@
 
 All notable changes to this project are documented here.
 
+## v7.2 - Button Robustness & Screen-Control Fixes (2026-08-04)
+
+**Summary**
+
+Bug-fix release that resolves the three control glitches reported for the v7.1
+firmware on the Seeed XIAO ESP32‑C3:
+
+- "It is 20:35 and I cannot scroll the values of the primary screen."
+- "Double click does not switch to the secondary screen."
+- "Strange behaviour at the end of the day, if there is no tomorrow's data
+  available yet and the time is let's say 22:15."
+
+No fee/VAT math, NVS layout, API scheduling or 48-hour scrolling behaviour
+was changed. The v7.1 negative-price provider fee logic is preserved
+verbatim.
+
+### Fix 1 – Primary-screen scroll works at any hour of the day
+
+**Symptom**
+
+Clicking the button on the primary screen appeared to do nothing — the
+display stayed on the current hour and refused to advance.
+
+**Root cause (two compounding bugs)**
+
+1. `displayPriceRow()` only blanked past hours while `currentHour < 22`:
+
+   ```cpp
+   if (localHourIndex < currentHour && currentHour < 22) {
+       lcd.print("                    "); return;
+   }
+   ```
+
+   After 22:00 the guard fell through, so the screen was allowed to repaint
+   already-finished morning hours (00:00 – 21:59). The moment the user
+   scrolled forward, the new "top" hour was visually overwritten by the
+   previous morning's data, making the screen look frozen.
+
+2. `displayPrimaryList()` contained an override:
+
+   ```cpp
+   if (currentHour >= 21 && timeOffsetHours > 0) {
+       displayStartHourOffset = 21 + timeOffsetHours;
+   }
+   ```
+
+   From 21:00 onward this pinned the top row at `21 + offset`. At 22:15
+   every click computed start = 22+offset, was then clamped to 21+offset,
+   and the user saw no movement.
+
+**Fix**
+
+- `displayPriceRow()`: simplified the past-hour guard to
+  `if (localHourIndex < currentHour) blank();` so past hours of today are
+  hidden at every hour of the day, not just before 22:00.
+- `displayPrimaryList()`: removed the `currentHour >= 21` override
+  entirely. Past-hour blanking is now handled correctly by Fix 1a, so the
+  override is no longer needed.
+
+### Fix 2 – Double-click reliably toggles to the secondary screen
+
+**Symptom**
+
+A quick double-click did nothing — the display stayed on the primary
+price view. In some cases the screen showed a stuck "Long press detected!
+Release to refresh" message right after the device booted or was reset.
+
+**Root cause**
+
+The double-click path itself was correct; it was being starved by a false
+"Long press detected!" that fired immediately after every reset. On the
+ESP32-C3 the button pin (configured as `INPUT_PULLUP`) floats HIGH for a
+few seconds during boot while the internal pull-up is settling and
+power-rail noise is ringing. Because `buttonPressStartTime` is
+initialised to `0`, the long-press detector's predicate
+`millis() - buttonPressStartTime >= 3000` evaluated to
+`millis() >= 3000` a few seconds after boot — the firmware interpreted
+the floating-pin noise as a genuine 3-second hold, cleared the LCD to:
+
+```
+Long press detected!
+Release to refresh
+```
+
+…and from then on the user could not see any prices to click on
+(single- and double-click recognisers both still ran, but their visible
+effect was hidden behind the long-press splash).
+
+**Fix**
+
+Added a single new global flag and gated the long-press detector on it:
+
+```cpp
+// New flag, set true the first time the pin is observed LOW after boot
+bool buttonEverReleased = false;
+
+// In the "reading went LOW" branch:
+if (reading == LOW) {
+    buttonPressStartTime = millis();
+    longPressDetected    = false;
+    buttonEverReleased   = true;   // v7.2
+}
+
+// In the long-press trip block:
+if (buttonState == LOW && !longPressDetected && buttonEverReleased) {  // v7.2
+    if (millis() - buttonPressStartTime >= longPressThreshold) {
+        longPressDetected = true;
+        // ... show "Long press detected! Release to refresh"
+    }
+}
+```
+
+The detector now refuses to fire until the user (or the power-rail noise)
+has released the button at least once. The v7.1 button logic (50 ms
+debounce, 3 s long-press threshold, 500 ms double-click window, TTP223
+timing) is otherwise preserved verbatim.
+
+### Fix 3 – End-of-day scroll is stable with no tomorrow data
+
+**Symptom**
+
+Around 22:00 – 23:59 with no tomorrow data in the buffer, scrolling
+through the primary screen produced a screen full of blank past-hour
+rows, or wrapped the start hour back to 00:00 in a confusing way.
+
+**Root cause**
+
+`advanceDisplayOffset()` contained a hack:
+
+```cpp
+if (allowedAhead < 2 && currentHour >= 21 && !isTomorrowDataAvailable)
+    allowedAhead = 2;
+```
+
+At 22:00 (with no tomorrow data) this let the user click past hour 23
+into "24:00 / 25:00". `displayStartHourOffset` then exceeded
+`maxOffsetLimit = 23` and the wrap logic:
+
+```cpp
+if (displayStartHourOffset > maxOffsetLimit)
+    displayStartHourOffset %= (maxOffsetLimit + 1);
+```
+
+…wrapped it back to 0. Combined with the buggy past-hour blanking in
+Fix 1a, the result was a screen full of stale blank rows from 00:00 to
+21:59.
+
+**Fix**
+
+Removed the `allowedAhead = 2` hack. The natural cap is now sufficient:
+
+- 22:00 → can step 22 → 23, then wraps back to current
+- 23:00 → cannot step forward at all
+
+No wrap to 00:00 of the previous day is reachable any more, and Fix 1a
+ensures any past hour that does briefly land on the screen is blanked
+correctly.
+
+### Fix 4 (bonus) – Auto-return timer now resets on every click
+
+**Symptom**
+
+Scrolling through the 20-line secondary status page (4 lines at a time)
+did not push the 10 s auto-return-to-top timeout forward — the display
+could jump back to the primary price view mid-read.
+
+**Root cause**
+
+`lastButtonActivity` and `autoScrollExecuted` were only updated inside the
+primary-list branches of `advanceDisplayOffset()`. The secondary-list
+branch scrolled the offset but did not touch the timer.
+
+**Fix**
+
+Moved the two resets to the very top of `advanceDisplayOffset()`:
+
+```cpp
+void advanceDisplayOffset() {
+    // Any successful click (single, double, or long-press-release) ends up
+    // here, so this is the single place that resets the auto-return timer.
+    lastButtonActivity = millis();
+    autoScrollExecuted = false;
+    // ... rest of the function unchanged
+}
+```
+
+### Other changes (cosmetic / non-behavioural)
+
+- Filename and three user-visible version strings bumped to v7.2:
+  - `connectToWiFi()` splash: `"Elec. Rate SI v7.1"` → `"v7.2"`
+  - `displaySecondaryList()` credit line (line 18): `"price ticker v7.1"` → `"v7.2"`
+  - `setup()` debug banner: `"Starting Dynamic Electricity Ticker v7.1 (Neg Price Fee) - DST-SAFE"`
+    → `"Starting Dynamic Electricity Ticker v7.2 (Button Robustness) - DST-SAFE"`
+- Inline comments added at each fix site explaining what v7.1 did wrong,
+  so future maintainers do not re-introduce the overrides.
+- New global flag `bool buttonEverReleased` (see Fix 2).
+
+### Files changed
+
+| File | Change |
+|---|---|
+| `ESP32_standalone_electricity_ticker_7_2.ino` | Filename, header comment, `buttonEverReleased` flag, `handleButton()` long-press gate, `displayPriceRow()` past-hour guard, `displayPrimaryList()` removed override, `advanceDisplayOffset()` timer reset, three version strings |
+
+---
+
+## v7.1 - Negative Price Provider Fee (2026-04-06)
+
+**Summary**
+
+Added a separate configurable provider fee for negative spot prices, correctly
+modelling contracts where the provider's fee structure differs between positive
+and negative market prices.
+
+### What changed
+
+**New constant (in `// Price computation` globals block):**
+```cpp
+const float NEG_PRICE_COMPANY_FEE_PERCENTAGE = 30.0;
+```
+
+**Price calculation is now:**
+
+| Market price | Formula |
+|---|---|
+| Positive (`raw >= 0`) | `raw × (1 + POWER_COMPANY_FEE_PERCENTAGE/100) × (1 + VAT_PERCENTAGE/100)` |
+| Negative (`raw < 0`) | `raw × (1 - NEG_PRICE_COMPANY_FEE_PERCENTAGE/100) × (1 + VAT_PERCENTAGE/100)` |
+
+The switch happens on the **raw API price** before any multiplier is applied.
+VAT is applied to both cases, consistent with net billing contracts where VAT
+is calculated on the monthly net sum (mathematically equivalent due to VAT
+being a linear multiplier).
+
+**Key values for `NEG_PRICE_COMPANY_FEE_PERCENTAGE`:**
+
+| Value | Meaning |
+|---|---|
+| `30.0` | Provider keeps 30%, pays you 70% of the negative market price |
+| `0.0` | Provider passes the full negative price to you (no fee deducted) |
+
+**All 5 fee calculation sites updated:**
+
+| Function | Purpose |
+|---|---|
+| `updateLeds()` | LED brightness reflects correct negative price |
+| `format15MinPrice()` | 15-min row values on primary display |
+| `displayPriceRow()` | Hourly price rows on primary display |
+| `displaySecondaryList()` | Daily average on secondary info screen |
+| Version strings | `connectToWiFi()` LCD and `displaySecondaryList()` credit line |
+
+---
+
+## v7.0 - Rolling 48-Hour Logic & Midnight Bridge (2026-04-03)
+
+**Summary**
+
+This is the **"Golden Build"** for this hardware platform. It combines all the hardware stability fixes from v6.2.4 with a revolutionary new 48-hour price prediction system that eliminates the "1 AM fetch gap" problem that plagues most electricity tickers.
+
+### New Features
+
+#### 1. Dual-Buffer NVS System
+
+The ticker now stores "Today" and "Tomorrow" data independently in NVS, allowing seamless display of up to 47 hours of price data.
+
+**New NVS Keys:**
+- `data_prc_t` – Raw JSON payload for tomorrow's prices
+- `data_store_t` – Unix timestamp when tomorrow's data was stored
+
+**New Global Variables:**
+- `StaticJsonDocument<Config::JSON_BUFFER_SIZE> docTomorrow` – Tomorrow's price data buffer
+- `bool isTomorrowDataAvailable` – Flag indicating tomorrow's data availability
+- `float averagePriceTomorrow` – Tomorrow's daily average price
+- `int lowestPriceIndexTomorrow` – Index of tomorrow's lowest price hour
+- `int highestPriceIndexTomorrow` – Index of tomorrow's highest price hour
+
+#### 2. The Midnight Bridge (Rollover Logic)
+
+**Problem:**
+Most electricity tickers fail at midnight because they rely on slow API calls to fetch new data. The Energy-Charts API typically doesn't publish next-day data until 1-2 AM, leaving users with a "No Data" screen for hours.
+
+**Solution:**
+The Midnight Bridge detects the moment the local clock moves from 23:59:59 to 00:00:00 and instantly promotes the pre-fetched "Tomorrow" data to become "Today" data.
+
+**Implementation (in `loop()`):**
+```cpp
+if (daycheck->tm_mday != trackedDay) {
+    // Midnight rollover detected
+    if (isTomorrowDataAvailable) {
+        // Swap tomorrow to today instantly
+        doc = docTomorrow;
+        docTomorrow.clear();
+
+        // Update all statistics
+        averagePrice = averagePriceTomorrow;
+        lowestPriceIndex = lowestPriceIndexTomorrow;
+        highestPriceIndex = highestPriceIndexTomorrow;
+
+        // Save to NVS and clear tomorrow slot
+        serializeJson(doc, payload);
+        saveDataToNVS(payload, false);
+        clearTomorrowNVS();
+
+        timeOffsetHours = 0;
+        displayPrices();
+    }
+}
+```
+
+**NVS Power-Failure Protection:**
+Immediately after the swap, the new "Today" data is serialized and saved to NVS. If power is cut at 00:05 AM, the device reboots with correct data already loaded.
+
+#### 3. Smart Fetching & Tomorrow's Data
+
+**Automatic Tomorrow Fetch:**
+After 14:00 (2 PM) local time, the ticker automatically fetches tomorrow's data using the `&start=YYYY-MM-DD` parameter:
+
+```cpp
+void fetchAndProcessData(bool fetchTomorrow) {
+    String url = api_url;
+    if (fetchTomorrow) {
+        time_t now = time(nullptr);
+        now += 24 * 3600; // Add 24 hours
+        struct tm* tmr = localtime(&now);
+        char dateStr[20];
+        snprintf(dateStr, sizeof(dateStr), "%04d-%02d-%02d",
+                 tmr->tm_year + 1900, tmr->tm_mon + 1, tmr->tm_mday);
+        url += "&start=";
+        url += dateStr;
+    }
+    // ... HTTP request follows
+}
+```
+
+**Smart Scheduling (`handleDataFetching()`):**
+```cpp
+struct tm* ti = localtime(&now);
+// Priority 1: If it's after 14:00 and we don't have tomorrow's data yet
+if (ti->tm_hour >= 14 && !isTomorrowDataAvailable) {
+    fetchAndProcessData(true); // Fetch tomorrow
+}
+```
+
+#### 4. Seamless 48H Scrolling
+
+**Extended Display Range:**
+When tomorrow's data is available, users can scroll up to **47 hours ahead**:
+
+```cpp
+int maxOffsetLimit = isTomorrowDataAvailable ? 47 : 23;
+if (displayStartHourOffset > maxOffsetLimit)
+    displayStartHourOffset %= (maxOffsetLimit + 1);
+```
+
+**Visual Distinction for Tomorrow:**
+Future hours are marked with `HH:>>` to clearly distinguish tomorrow's prices from today's:
+
+```cpp
+if (showTomorrow) {
+    snprintf(buffer, sizeof(buffer), "%02d:>>", localHourIndex);
+} else {
+    snprintf(buffer, sizeof(buffer), "%02d:00", localHourIndex);
+}
+```
+
+**Correct Min/Max Indicators:**
+The code correctly uses tomorrow's statistics when displaying future hours:
+
+```cpp
+int lowIdx = showTomorrow ? lowestPriceIndexTomorrow : lowestPriceIndex;
+int highIdx = showTomorrow ? highestPriceIndexTomorrow : highestPriceIndex;
+```
+
+#### 5. Hardware Stability (Preserved from v6.2.4)
+
+All v6.2.4 stability fixes remain intact:
+
+- **State-Based Refresh**: Display updates exactly at 00, 15, 30, and 45 minutes past the hour, even if the CPU is busy
+- **LED Indicators Pinned to Current**: White LED and built-in LED reflect actual current prices, regardless of what the user is viewing on screen
+
+### Technical Implementation Details
+
+#### Dual-Buffer Display Helpers
+
+**`display15MinuteDetails(int row, int totalHourOffset)`:**
+- Now accepts `totalHourOffset` (0-47) instead of just hour index
+- Automatically selects correct buffer (`doc` or `docTomorrow`) based on offset
+- Shows past segments ("> ") for current hour
+
+**`displayPriceRow(int row, int totalHourOffset, bool isCurrentHourRow)`:**
+- Extended to handle tomorrow's data with visual indicators
+- Correctly applies hour suppression logic only to today's hours
+
+#### NVS Persistence Updates
+
+**`saveDataToNVS(const String& rawJson, bool isTomorrow)`:**
+```cpp
+if (isTomorrow) {
+    preferences.putString("data_prc_t", rawJson);
+    preferences.putULong("data_store_t", (unsigned long)now);
+} else {
+    // Original "today" save logic
+    preferences.putInt("data_day", timeinfo.tm_mday);
+    // ...
+}
+```
+
+**`loadDataFromNVS()`:**
+- Now loads both today and tomorrow data from NVS
+- Validates and processes both buffers independently
+
+#### API Date Validation
+
+The `processJsonData()` function now validates data against the correct target date:
+
+```cpp
+time_t targetTime = time(nullptr);
+if (isTomorrow) targetTime += 24 * 3600;
+struct tm* targetDayTm = localtime(&targetTime);
+
+bool sameDate = (lastDataTm->tm_mday == targetDayTm->tm_mday &&
+                 lastDataTm->tm_mon == targetDayTm->tm_mon &&
+                 lastDataTm->tm_year == targetDayTm->tm_year);
+```
+
+### Why This Is the "Golden Build"
+
+| Feature | v6.2.4 | v7.0 |
+|---------|--------|------|
+| Display hours ahead | 23 hours (today only) | 47 hours (today + tomorrow) |
+| Midnight transition | "No Data" until API updates | Seamless swap from buffer |
+| Power failure resilience | Relies on API availability | NVS contains valid data |
+| Visual tomorrow indication | None | `HH:>>` format |
+| Tomorrow min/max markers | N/A | Correct indices |
+| Fetch strategy | Once per day | Smart: today + tomorrow after 14:00 |
+
+### User Experience: Behavior & Display States
+
+The display changes based on which data buffer is being used and the status of the fetch:
+
+| **State** | **Display Output** | **LED Behavior** |
+|----------|-------------------|-----------------|
+| **Normal (Today)** | Shows current prices and 15-min details. Hours are marked as HH:00. | White LED reflects current price status (Breathe, Solid, or Blink). |
+| **Scrolling (Tomorrow)** | Future prices are displayed. Hours are marked with HH:>> to indicate "Tomorrow". | **Pinned to Today:** The LEDs continue showing the _actual current_ price status even while you scroll through tomorrow. |
+| **No Data** | Displays: "No data for today, Press & hold to, refresh manually." | White LED is turned **OFF** to avoid misleading price signals. |
+| **Connecting** | "Elec. Rate SI v7.0" followed by "Connecting..." and progress dots. | Built-in LED is **OFF** until connection is established. |
+
+### API Call Intervals & Retry Strategy (v7.0)
+
+The exact API call intervals in version 7.0 vary depending on the device's state, data availability, and time of day:
+
+#### Primary Scheduling (Daily Fetch)
+
+The device aims to maintain a rolling 48-hour data window by fetching today's and tomorrow's data at specific times:
+
+- **Initial Boot:** An API call is attempted immediately upon startup and time synchronization.
+- **Tomorrow's Data (Smart Fetching):** Starting at **14:00 (2 PM) local time**, the device begins checking for the next day's prices. It will attempt to fetch this data periodically until successful.
+- **Midnight Rollover:** At exactly **00:00:00**, the device "promotes" tomorrow's data to the today buffer. If tomorrow's data was already successfully fetched and stored, **no API call is needed at midnight**.
+
+#### Retry Logic (Exponential Backoff)
+
+If a scheduled API call fails (e.g., due to a temporary server error or WiFi glitch), the device uses a safety-oriented retry interval:
+
+- **Max Retries:** 5 attempts (`HTTP_GET_RETRY_MAX`)
+- **Interval Formula:** Uses a backoff factor of **2** (`HTTP_GET_BACKOFF_FACTOR`)
+- **Typical Progression:** After a failure, it waits a short period, then doubles that wait time for each subsequent failure until the maximum retry count is reached
+
+#### "Midnight Phase" Recovery
+
+If the device reaches midnight but **does not** have tomorrow's data ready (meaning the afternoon fetches failed), it enters a high-priority state called `midnightPhaseActive`:
+
+- **Interval:** It bypasses the standard daily schedule and retries the API **more aggressively** (initially every minute).
+- **Goal:** To clear the "No Data" screen and restore the price display as quickly as possible once the energy provider's server updates.
+
+#### Background Monitoring
+
+While not a full API call, the device performs these checks constantly:
+
+- **Loop Pacing:** The main system loop runs every **100ms** to check if it's time for a scheduled fetch.
+- **Display Refresh:** The screen logic checks the time every loop but only refreshes the UI every **15 minutes** (at :00, :15, :30, :45) to match the price data intervals.
+
+---
+
+## v6.2.4 - Exact-boundary display refresh bug (2026-04-01):
+
+**Summary**
+
+Top of the hour auto display refresh glitch fix where display automatically refreshed but showed the PREVIOUS hour's data.
+
+### Problem:
+- At the exact top of the hour (e.g., 20:00:00), the display automatically refreshed but showed the PREVIOUS hour's data (19:00). This happened because the "next-boundary" rounding logic in findCurrentPriceIndex() incorrectly excluded the current interval if the time was exactly on the boundary.
+
+### Solution:
+- Simplified findCurrentPriceIndex() to use a robust "last entry <= now" comparison. This ensures the display transitions to the new hour instantaneously at XX:00:00.
+
+---
+
+## v6.2.3 - State-based display refresh logic fix (2026-04-01):
+
+**Summary**
+
+The refresh logic should be "State-Based" rather than "Event-Based." Instead of checking if the minute is zero, it should check if the current hour is different from the last recorded hour.
+
+### Problem: Screen would occasionally fail to update if the ESP32 was busy
+   - fetching data or reconnecting WiFi) during the exact 00/15/30/45 minute mark.
+
+### Solution: Switched from "Event-Based" (refresh only AT minute X) to "State-Based"
+
+    (refresh IF current time != last refresh time).
+  - This ensures the screen updates immediately even if the device was busy during the transition.
+
+---
+
+## v6.2.2 - Display blank lines issue fix (2026-03-31):
+
+**Summary**
+
+Fixed a bug where the display was showing blank lines
+
+### Problem: Sometimes rows 0 and 1 (current 15-min prices and current hour) were blank
+
+**Cause:** The "hour suppression" logic was hiding the current hour unexpectedly
+
+### Solution:
+
+  - Row 1 (current hour) now ALWAYS shows - suppression logic only applies to rows 2-3
+  - Row 0 (15-min details) also always shows for the current hour
+
 ---
 
 ## v6.2.1 – Current Interval Fix (2026‑03‑29)
@@ -40,9 +566,9 @@ for (size_t i = unixSeconds.size(); i > 0; i--) {
 ```
 
 **Example:**
-- At 17:57: nextQuarter = 18:00, finds last entry < 18:00 = 17:45 ✅
-- At 18:00: nextQuarter = 18:15, finds last entry < 18:15 = 18:00 ✅
-- At 18:46: nextQuarter = 19:00, finds last entry < 19:00 = 18:45 ✅
+- At 17:57: nextQuarter = 18:00, finds last entry < 18:00 = 17:45
+- At 18:00: nextQuarter = 18:15, finds last entry < 18:15 = 18:00
+- At 18:46: nextQuarter = 19:00, finds last entry < 19:00 = 18:45
 
 ---
 
@@ -112,7 +638,7 @@ int findPriceIndexForHour(const JsonArray& unixSeconds, int targetHour) {
 ### Why This Is Future-Proof
 
 | Scenario | Code Behavior |
-|----------|--------------|
+|----------|---------------|
 | Normal days (96 entries) | Works as before |
 | DST spring forward (92 entries) | Timestamp lookup finds correct indices |
 | DST fall back (100 entries) | Timestamp lookup finds correct indices |

README.md

@@ -11,19 +11,121 @@ This project is an Arduino‑IDE‑friendly firmware for the **Seeed XIAO ESP32
 - Uses a white LED and an optional presence sensor to give quick visual feedback.
 - Stores daily price data in **NVS** to survive reboots and reduce API calls.
 
-The latest sketch implements **Version 6.2.1**.
+The latest sketch implements **Version 7.2** — a bug-fix release that
+restores primary-screen scrolling, fixes double-click → secondary-screen
+switching on the ESP32-C3, and stabilises end-of-day behaviour when no
+tomorrow data is available yet. The v7.1 negative-price provider fee logic
+is preserved unchanged.
 
 ---
 
 ## Version Highlights
 
+### v7.2 - Button Robustness & Screen-Control Fixes (2026-08-04)
+
+Bug-fix release. Resolves the three control glitches reported for v7.1:
+"cannot scroll the primary screen at 20:35", "double-click does not switch
+to the secondary screen", and "strange end-of-day behaviour at 22:15 with
+no tomorrow data". No fee/VAT math, NVS layout, API scheduling or
+48-hour scrolling behaviour was changed.
+
+- **Fix 1 – Primary-screen scroll** works at any hour of the day:
+  past-hour blanking in `displayPriceRow()` simplified from
+  `currentHour < 22` to a plain `localHourIndex < currentHour`, and the
+  `currentHour >= 21` override in `displayPrimaryList()` removed.
+- **Fix 2 – Double-click** reliably toggles to the secondary screen.
+  A new `bool buttonEverReleased` flag prevents a false
+  "Long press detected!" from firing right after every reset on the
+  ESP32-C3 (floating button pin + `buttonPressStartTime = 0` was making
+  the long-press detector trip on phantom 3-second holds during boot).
+- **Fix 3 – End-of-day scroll** is stable with no tomorrow data. The
+  `allowedAhead = 2` hack in `advanceDisplayOffset()` is gone, so the
+  user can no longer scroll into "24:00 / 25:00" and wrap back to 00:00.
+- **Fix 4 (bonus) – Auto-return timer** now resets on every click, so
+  scrolling the secondary status page no longer jumps back to the primary
+  view mid-read.
+
+See [`VERSION.md`](./VERSION.md) for the highlights and
+[`CHANGELOG.md`](./CHANGELOG.md) for full implementation details.
+
+---
+
+### v7.1 - Negative Price Provider Fee (2026-04-06)
+
+Added a separate configurable provider fee for negative spot prices, correctly
+modelling contracts where the provider's fee structure differs between positive
+and negative market prices.
+
+**New constant:**
+```cpp
+const float NEG_PRICE_COMPANY_FEE_PERCENTAGE = 30.0;
+```
+
+**Price calculation is now:**
+
+| Market price | Formula |
+|---|---|
+| Positive (`raw >= 0`) | `raw × (1 + POWER_COMPANY_FEE_PERCENTAGE/100) × (1 + VAT_PERCENTAGE/100)` |
+| Negative (`raw < 0`) | `raw × (1 - NEG_PRICE_COMPANY_FEE_PERCENTAGE/100) × (1 + VAT_PERCENTAGE/100)` |
+
+The switch happens on the **raw API price** before any multiplier is applied.
+VAT is applied to both cases, consistent with net billing contracts where VAT
+is calculated on the monthly net sum (mathematically equivalent due to VAT
+being a linear multiplier).
+
+**Key values for `NEG_PRICE_COMPANY_FEE_PERCENTAGE`:**
+
+| Value | Meaning |
+|---|---|
+| `30.0` | Provider keeps 30%, pays you 70% of the negative market price |
+| `0.0` | Provider passes the full negative price to you (no fee deducted) |
+
+All 5 fee calculation sites updated: `updateLeds()`, `format15MinPrice()`,
+`displayPriceRow()`, `displaySecondaryList()` (daily average), and version strings.
+
+---
+
+### v7.0 - Rolling 48-Hour Logic & Midnight Bridge (Major Upgrade)
+
+This version is the **"Golden Build"** for this hardware platform. It combines all hardware stability fixes from v6.2.4 with a revolutionary new 48-hour price prediction system.
+
+#### Key New Features
+
+- **Midnight Bridge**: Instantly promotes pre-fetched tomorrow's data to become today's data at midnight, eliminating the "1 AM fetch gap"
+- **Dual-Buffer NVS**: Stores "Today" and "Tomorrow" data independently
+- **47-Hour Scrolling**: View up to 47 hours of price data when tomorrow's data is available
+- **Visual Tomorrow Indicators**: Future hours are marked with `HH:>>` format
+- **Smart Fetching**: Automatically fetches tomorrow's data after 14:00 (2 PM)
+
+#### Technical Highlights
+
+- **Instant Midnight Transition**: No more "No Data" screen at midnight
+- **Power-Failure Resilience**: New day's data is saved to NVS immediately after midnight swap
+- **Correct Min/Max for Tomorrow**: Price indicators correctly reference tomorrow's statistics
+- **LED Indicators Pinned to Current**: White LED always reflects actual current prices
+
+### v6.2.4 - Exact-boundary display refresh bug (critical fix of v6.2.3 update)
+- Problem: At the exact top of the hour (e.g., 20:00:00), the display automatically refreshed but showed the PREVIOUS hour's data (19:00). This happened because the "next-boundary" rounding logic in findCurrentPriceIndex() pre-calculated the next boundary.
+- Fix: Simplified findCurrentPriceIndex() to use a robust "last entry <= now" comparison. This ensures the display transitions to the new hour instantaneously at XX:00:00.
+
+### v6.2.3 - State-based display refresh logic (critical fix of v6.2.2 update)
+- Problem: Screen would occasionally fail to update if the ESP32 was busy (fetching data or reconnecting WiFi) during the exact 00/15/30/45 minute mark.
+- Fix: Switched from "Event-Based" (refresh only AT minute X) to "State-Based" (refresh IF current time != last refresh time). This ensures the screen updates immediately even if the device was busy during the transition.
+
+### v6.2.2 - Display Blank Lines Issue Fix (critical fix of v6.2.1 update)
+  - Problem: Sometimes rows 0 and 1 (current 15-min prices and current hour) were blank.
+  - Cause: The "hour suppression" logic was hiding the current hour unexpectedly.
+  - Fix:
+    - Row 1 (current hour) now ALWAYS shows - suppression logic only applies to rows 2-3.
+    - Row 0 (15-min details) also always shows for the current hour.
+
 ### v6.2.1 – Current Interval Fix (critical fix of v6.2.0 update)
 - Fixed display showing prices one hour ahead of the current time.
 - `findCurrentPriceIndex()` now correctly returns the current 15-minute interval.
 
 Major update sketch implements **Version 6.2.0**, focusing on:
 
-- **Version 6.2.0 FIX**: **DST (Daylight Saving Time) handling fully fixed** – the ticker now works correctly on ALL days including DST switch days (spring forward and fall back). Uses timestamp-based price lookups instead of arithmetic calculations.
+- **Version 6.2.0 FIX**: **DST (Daylight Saving Time) handling fully fixed** – the ticker now works correctly on ALL days including DST switch days (spring forward and fall back). Uses timestamp-based lookups throughout.
 - Version 6.1.2 fix: restore correct **white LED indicator** behavior (ESP32 PWM fix; no dim glow when off).
 - Version 6.1.1 fix: Correct daily **low/high hourly markers** (now includes negative and **0.0** prices).
 - Daily (not hourly) API fetching.
@@ -36,7 +138,7 @@ Major update sketch implements **Version 6.2.0**, focusing on:
 
 ## DST (Daylight Saving Time) – How It Works
 
-### v6.2.0: Fully DST-Safe
+### v6.2.0+: Fully DST-Safe
 
 **Important**: Starting with v6.2.0, the ticker is **fully DST-safe** and requires **no manual intervention** on DST switch days.
 
@@ -44,9 +146,9 @@ The firmware uses **timestamp-based price lookups** that work correctly regardle
 
 | Day Type | Hours in Day | Price Entries | Status |
 |----------|-------------|---------------|--------|
-| Normal | 24 | 96 | ✅ Works |
-| Spring forward (March) | 23 | 92 | ✅ Works (fixed in v6.2.0) |
-| Fall back (October) | 25 | 100 | ✅ Works (fixed in v6.2.0) |
+| Normal | 24 | 96 | Works |
+| Spring forward (March) | 23 | 92 | Works (fixed in v6.2.0) |
+| Fall back (October) | 25 | 100 | Works (fixed in v6.2.0) |
 
 ### Timezone Configuration
 
@@ -76,6 +178,144 @@ The rest of the code works unchanged because it uses timestamp-based lookups.
 
 ---
 
+## The Midnight Bridge (v7.0)
+
+### The Problem with Traditional Tickers
+
+Most electricity tickers fail at midnight because they rely on slow API calls to fetch new data. The Energy-Charts API typically doesn't publish next-day data until 1-2 AM, leaving users with a "No Data" screen for hours.
+
+### The Solution: Midnight Bridge
+
+The Midnight Bridge detects the moment the local clock moves from 23:59:59 to 00:00:00 and instantly promotes the pre-fetched "Tomorrow" data to become "Today" data.
+
+**How it works:**
+
+1. **Pre-fetching**: After 14:00 (2 PM), the ticker automatically fetches tomorrow's prices using the `&start=YYYY-MM-DD` API parameter
+2. **Buffer Storage**: Tomorrow's data is stored in a separate NVS slot (`data_prc_t`)
+3. **Midnight Detection**: The main loop detects day rollover by comparing `tm_mday`
+4. **Instant Swap**: At 00:00:00, tomorrow's buffer instantly becomes today's data
+5. **NVS Persistence**: New day's data is saved immediately after swap (power-failure protection)
+
+### Power-Failure Protection
+
+Immediately after the midnight swap, the new "Today" data is serialized and saved to NVS. If power is cut at 00:05 AM, the device reboots with correct data already loaded.
+
+---
+
+## Dual-Buffer System (v7.0)
+
+The v7.0 firmware implements a dual-buffer system that stores today and tomorrow data independently:
+
+### Buffer Comparison
+
+| Buffer | Variable | NVS Keys | Contents |
+|--------|----------|----------|----------|
+| Today | `doc` | `data_prc`, `data_day`, `data_mon`, `data_year` | Current day's prices |
+| Tomorrow | `docTomorrow` | `data_prc_t`, `data_store_t` | Next day's prices |
+
+### Statistics Per Buffer
+
+Each buffer maintains its own statistics:
+- **Daily average**: `averagePrice` / `averagePriceTomorrow`
+- **Lowest price index**: `lowestPriceIndex` / `lowestPriceIndexTomorrow`
+- **Highest price index**: `highestPriceIndex` / `highestPriceIndexTomorrow`
+
+### Display Selection
+
+The display logic automatically selects the correct buffer based on the time offset:
+
+```cpp
+bool showTomorrow = (totalHourOffset >= 24);
+StaticJsonDocument<Config::JSON_BUFFER_SIZE>& targetDoc = showTomorrow ? docTomorrow : doc;
+int lowIdx = showTomorrow ? lowestPriceIndexTomorrow : lowestPriceIndex;
+```
+
+---
+
+## 48-Hour Scrolling (v7.0)
+
+### Extended Range
+
+When tomorrow's data is available, users can scroll up to **47 hours ahead**:
+
+```cpp
+int maxOffsetLimit = isTomorrowDataAvailable ? 47 : 23;
+```
+
+### Visual Tomorrow Indication
+
+Future hours (tomorrow) are displayed with `HH:>>` format to clearly distinguish them from today's hours:
+
+```
+Today's hour:  14:00 | Tomorrow's hour: 14:>>
+```
+
+### Correct Min/Max Indicators
+
+The low/high price markers (arrows) correctly reference tomorrow's statistics when viewing tomorrow's hours:
+
+```cpp
+if (dataIndex == lowIdx) {
+    lcd.write(byte(3)); // Low price arrow
+}
+```
+
+---
+
+## Behavior & Display States (v7.2)
+
+The display changes based on which data buffer is being used and the status of the fetch:
+
+| **State** | **Display Output** | **LED Behavior** |
+|----------|-------------------|-----------------|
+| **Normal (Today)** | Shows current prices and 15-min details. Hours are marked as HH:00. | White LED reflects current price status (Breathe, Solid, or Blink). |
+| **Scrolling (Tomorrow)** | Future prices are displayed. Hours are marked with HH:>> to indicate "Tomorrow". | **Pinned to Today:** The LEDs continue showing the _actual current_ price status even while browsing future hours. |
+| **No Data** | Displays: "No data for today, Press & hold to, refresh manually." | White LED is turned **OFF** to avoid misleading price signals. |
+| **Connecting** | "Elec. Rate SI v7.2" followed by "Connecting..." and progress dots. | Built-in LED is **OFF** until connection is established. |
+
+### Key UX Principle: LEDs Stay Pinned to Current Time
+
+Unlike the display which can scroll through future hours, the white LED **always** reflects the actual current price status. This means:
+- Even while browsing tomorrow's cheap hours, the LED tells you the **true current** price situation
+- This prevents confusion and helps you decide "should I turn on the dishwasher **now**?"
+
+---
+
+## API Call Intervals & Retry Strategy (v7.0)
+
+### Primary Scheduling (Daily Fetch)
+
+The device aims to maintain a rolling 48-hour data window by fetching today's and tomorrow's data at specific times:
+
+- **Initial Boot:** An API call is attempted immediately upon startup and time synchronization.
+- **Tomorrow's Data (Smart Fetching):** Starting at **14:00 (2 PM) local time**, the device begins checking for the next day's prices. It will attempt to fetch this data periodically until successful.
+- **Midnight Rollover:** At exactly **00:00:00**, the device "promotes" tomorrow's data to the today buffer. If tomorrow's data was already successfully fetched and stored, **no API call is needed at midnight**.
+
+### Retry Logic (Exponential Backoff)
+
+If a scheduled API call fails (e.g., due to a temporary server error or WiFi glitch), the device uses a safety-oriented retry interval:
+
+- **Max Retries:** 5 attempts (`HTTP_GET_RETRY_MAX = 5`)
+- **Backoff Factor:** 2 (`HTTP_GET_BACKOFF_FACTOR = 2`)
+- **Typical Progression:** After a failure, it waits a short period, then doubles that wait time for each subsequent failure until the maximum retry count is reached
+
+### "Midnight Phase" Recovery
+
+If the device reaches midnight but **does not** have tomorrow's data ready (meaning the afternoon fetches failed), it enters a high-priority state called `midnightPhaseActive`:
+
+- **Behavior:** Bypasses the standard daily schedule and retries the API **more aggressively**
+- **Initial Interval:** Attempts every minute until successful
+- **Goal:** Clear the "No Data" screen and restore the price display as quickly as possible once the energy provider's server updates
+
+### Background Monitoring
+
+While not making API calls constantly, the device performs these checks continuously:
+
+- **Loop Pacing:** The main system loop runs every **100ms** to check if it's time for a scheduled fetch
+- **Display Refresh:** The screen logic checks the time every loop but only refreshes the UI every **15 minutes** (at :00, :15, :30, :45) to match the price data intervals
+
+---
+
 ## Bidding Zones (BZN) / Region Selection
 
 The firmware currently uses:
@@ -92,9 +332,9 @@ const char* api_url = "https://api.energy-charts.info/price?bzn=SI";
 
 to any supported BZN.
 
-All available bidding zones (from the original README):
+All available bidding zones:
 
-- `AT` ‑ Austria 
+- `AT` ‑ Austria
 - `BE` ‑ Belgium
 - `BG` ‑ Bulgaria
 - `CH` ‑ Switzerland
@@ -146,7 +386,7 @@ All available bidding zones (from the original README):
 
 ## Hardware Setup (Detailed)
 
-This section merges the original v5.5 instructions with the current v6.1 hardware expectations.  
+This section merges the original v5.5 instructions with the current v7.2 hardware expectations.
 Follow it carefully to reproduce the working setup.
 
 ### 1. Microcontroller
@@ -166,7 +406,7 @@ Typical pins used in the sketch:
 ### 2. 20x4 I²C LCD (2004) – PCF8574 Backpack
 
 - LCD: **20x4 2004 character display** with I²C backpack (PCF8574 or compatible).
-- Default I²C address (in code): `0x27`  
+- Default I²C address (in code): `0x27`
   (Change in the sketch if your module differs: `LiquidCrystal_I2C lcd(0x27, 20, 4);`)
 
 **Connections:**
@@ -283,7 +523,7 @@ The sketch uses a **white LED** (or LED strip control line) on `GPIO 5` (`whiteL
 - Ensure the **strip power supply shares ground** with the ESP32‑C3 board.
 - Do **not** drive large loads directly from the GPIO pin.
 
-The LED is driven with various patterns to indicate price level; see “LED Price Signalling” below.
+The LED is driven with various patterns to indicate price level; see "LED Price Signalling" below.
 
 ---
 
@@ -296,29 +536,39 @@ The LED is driven with various patterns to indicate price level; see “LED Pric
 
 ---
 
-## Firmware Features (v6.2.0)
+## Firmware Features (v7.2)
 
 ### Core Display & Pricing
 
 - Data source: `https://api.energy-charts.info/price?bzn=SI`
 - Resolution: 15‑minute intervals with hourly averages
-- Display shows:
+- Display shows up to **47 hours** of price data (when tomorrow's data is available)
   - **Row 0**: Current hour, four 15‑minute values
   - **Rows 1–3**: Current hour + next two hours as hourly averages
-- Price calculation: Raw MWh → EUR/kWh with configurable surcharges (power company fee + VAT)
-  - Two configurable surcharges:
-    - `POWER_COMPANY_FEE_PERCENTAGE` (default `12.0` %).
-    - `VAT_PERCENTAGE` (default `22.0` %).
+- **v7.0 Feature**: Tomorrow's hours are marked with `HH:>>` format
+- Price calculation: Raw MWh → EUR/kWh with configurable surcharges
+  - Three configurable constants:
+    - `POWER_COMPANY_FEE_PERCENTAGE` (default `12.0` %) — fee for **positive** spot prices
+    - `NEG_PRICE_COMPANY_FEE_PERCENTAGE` (default `30.0` %) — fee kept by provider on **negative** spot prices
+    - `VAT_PERCENTAGE` (default `22.0` %)
+  - **v7.1**: Positive and negative spot prices use independent fee multipliers:
+
+    | Market price | Formula |
+    |---|---|
+    | Positive (`raw >= 0`) | `raw × (1 + POWER_COMPANY_FEE_PERCENTAGE/100) × (1 + VAT_PERCENTAGE/100)` |
+    | Negative (`raw < 0`) | `raw × (1 - NEG_PRICE_COMPANY_FEE_PERCENTAGE/100) × (1 + VAT_PERCENTAGE/100)` |
+
 - LCD:
   - `LiquidCrystal_I2C` with custom characters for:
     - Local language letters.
     - Low‑price and high‑price indicators.
 - **Daily min/max markers**:
-  - The low/high hourly indicators consider **negative**, **0.0**, and positive prices (v6.1.1 fix).
+  - The low/high hourly indicators consider **negative**, **0.0**, and positive prices
+  - **v7.0 Feature**: Tomorrow's min/max indices are tracked separately and displayed correctly
 
 ### LED Price Signalling
 
-The white LED (GPIO 5) reflects the **current 15‑minute interval** price:
+The white LED (GPIO 5) reflects the **current 15‑minute interval** price (regardless of what's displayed on screen):
 
 | Price Level | LED Behavior |
 |-------------|--------------|
@@ -355,40 +605,45 @@ LED is **disabled** when:
 One button (or touch) on GPIO 4 controls the UI:
 
 - **Single short press**:
-  - On primary screen: scrolls the time offset (future hours).
+  - On primary screen: scrolls the time offset (future hours up to 47h in v7.0).
   - On secondary screen: scrolls through the 20‑line status text (4 lines at a time).
 - **Double press**:
   - Toggles between:
     - Primary price view.
     - Secondary status/info view.
-- **Long press (~3 seconds in v6.1)**:
+- **Long press (~3 seconds)**:
   - While held:
-    - LCD shows: “Long press detected! Release to refresh”.
+    - LCD shows: "Long press detected! Release to refresh".
   - On release:
     - Forces a **manual data refresh**:
       - Sets `nextScheduledFetchTime = now`.
-      - Shows “Manual Refresh… Please wait…”.
+      - Shows "Manual Refresh… Please wait…".
       - `handleDataFetching()` will perform an immediate API fetch outside the normal schedule.
 
-An **auto‑scroll timeout** resets the view to “current hour / top of lists” after inactivity.
+An **auto‑scroll timeout** resets the view to "current hour / top of lists" after inactivity.
 
 ---
 
-## NVS Storage (Daily Data Cache)
+## NVS Storage (v7.0: Enhanced with Dual Buffers)
 
 This firmware uses ESP32‑C3 **Preferences API** (`Preferences`) under namespace `"my-ticker"`.
 
-Stored keys:
+### Stored Keys (v7.0)
 
-- **Wi‑Fi credentials:**
-  - `ssid`
-  - `pass`
-- **Daily price data:**
-  - `data_day`   – calendar day (1–31)
-  - `data_mon`   – month (0–11)
-  - `data_year`  – full year (e.g. 2026)
-  - `data_prc`   – full raw JSON payload from the API
-  - `data_last_store` – Unix time (`time_t`) when data was last written
+**Wi‑Fi credentials:**
+- `ssid`
+- `pass`
+
+**Today's price data:**
+- `data_day`   – calendar day (1–31)
+- `data_mon`   – month (0–11)
+- `data_year`  – full year (e.g. 2026)
+- `data_prc`   – full raw JSON payload from the API
+- `data_last_store` – Unix time (`time_t`) when data was last written
+
+**Tomorrow's price data (v7.0 new):**
+- `data_prc_t` – full raw JSON payload for next day
+- `data_store_t` – Unix time when tomorrow's data was stored
 
 ### On Boot
 
@@ -397,22 +652,32 @@ After successful NTP time sync:
 1. Attempt to load `data_day`, `data_mon`, `data_year`, and `data_prc` from NVS.
 2. If **stored date matches current local date**:
    - Deserialize `data_prc` into `StaticJsonDocument doc`.
-   - Run `processJsonData()` as if it were fresh from the API.
+   - Run `processJsonData(false)` as if it were fresh from the API.
    - Set `isTodayDataAvailable = true`.
    - **Skip** the initial API call to save traffic.
-3. If the stored date does **not** match today or JSON parsing fails:
+3. Attempt to load tomorrow's data from `data_prc_t`.
+4. If the stored date does **not** match today or JSON parsing fails:
    - NVS data is **ignored** for display.
-   - System starts from “No data for today”.
+   - System starts from "No data for today".
    - Schedules an immediate API fetch.
 
-### After Each Successful Fetch for Today
+### After Each Successful Fetch
 
-- Raw JSON payload is stored into NVS as `data_prc`, along with date (`data_day`, `data_mon`, `data_year`) and `data_last_store`.
-- On reboot later the same day, the device will show prices immediately from NVS without hitting the API.
+- Today's data: Raw JSON payload is stored into NVS as `data_prc`, along with date and `data_last_store`.
+- Tomorrow's data (v7.0): After 14:00, tomorrow's payload is stored as `data_prc_t` with `data_store_t`.
+
+### Midnight Bridge NVS Update (v7.0)
+
+At midnight rollover:
+1. Tomorrow's buffer is swapped to become today's buffer
+2. New "today" data is immediately serialized and saved to NVS
+3. Tomorrow's NVS slot is cleared
+
+This ensures power-failure resilience: if power is lost immediately after midnight, the device boots with valid data.
 
 ---
 
-## Daily Fetch Strategy (v6.1.0+)
+## Daily Fetch Strategy (v7.0: Enhanced with Smart Tomorrow Fetching)
 
 ### Goals
 
@@ -420,17 +685,18 @@ After successful NTP time sync:
 - Fetch:
   - Once after boot (if no valid NVS data for today).
   - Once per **new day** (after midnight), with robust retries while the next‑day dataset is not yet published.
+  - **NEW in v7.0**: Tomorrow's data automatically after 14:00 local time.
 
 ### Time Sync & First Fetch
 
 - `configTzTime(TZ_CET_CEST, "pool.ntp.org")` is used to enable CET/CEST aware `localtime()` and `getLocalTime()`.
-- Until time sync completes, the UI only shows “Syncing Time… Please wait…”.
+- Until time sync completes, the UI only shows "Syncing Time… Please wait…".
 - On first successful sync:
   - `isTimeSynced = true`.
   - `trackedDay` is set to the current `tm_mday`.
-  - Either NVS is used (if it has today’s data) or an initial fetch is scheduled.
+  - Either NVS is used (if it has today's data) or an initial fetch is scheduled.
 
-### Day‑Rollover Detection
+### Day‑Rollover Detection (v7.0: Enhanced with Midnight Bridge)
 
 In the main `loop()`:
 
@@ -440,109 +706,45 @@ In the main `loop()`:
   - If `tm_mday != trackedDay`:
     - Day rollover detected (midnight).
     - `trackedDay` updated.
-    - Immediately:
-      - `isTodayDataAvailable = false`.
-      - `displayState = NO_DATA_OFFSET`.
-      - `timeOffsetHours = 0`.
-      - White LED turned off.
-      - **Midnight phase** is entered:
-        - `midnightPhaseActive = true`.
-        - `midnightRetryCount = 0`.
-      - `nextScheduledFetchTime = now` (immediate attempt).
-      - LCD updated to “No data for today. Press & hold to refresh manually”.
+    - **v7.0 Midnight Bridge Logic**:
+      - If tomorrow's data is available:
+        - Instantly swap `docTomorrow` to `doc`
+        - Update all statistics (`averagePrice`, `lowestPriceIndex`, etc.)
+        - Save to NVS and clear tomorrow slot
+        - Reset `timeOffsetHours` to 0
+      - If tomorrow's data is NOT available:
+        - Enter "No Data" mode
+        - Start midnight retry phase
 
-### “Today” Detection (Market Day Logic)
+### Smart Tomorrow Fetching (v7.0)
 
-The Energy‑Charts API can keep serving **yesterday’s** market day for some time after local midnight.  
-To avoid accidentally accepting yesterday’s data as today’s, v6.1 uses a more robust rule.
+After 14:00 local time, if tomorrow's data is not yet available:
+
+```cpp
+if (ti->tm_hour >= 14 && !isTomorrowDataAvailable) {
+    fetchAndProcessData(true); // Fetch tomorrow's data
+}
+```
+
+The API URL is constructed with the `&start=YYYY-MM-DD` parameter for the next day.
+
+### "Today" Detection (Market Day Logic)
+
+The Energy‑Charts API can keep serving **yesterday's** market day for some time after local midnight.
+To avoid accidentally accepting yesterday's data as today's, v6.1+ uses a more robust rule.
 
 In `processJsonData()`:
 
 1. Read `unix_seconds[]`.
-2. Interpret the **LAST** timestamp as representing the end of the dataset’s market day.
+2. Interpret the **LAST** timestamp as representing the end of the dataset's market day.
 3. Convert it to local time (`localtime()`).
-4. Compare its date (day, month, year) to the current local date.
+4. Compare its date (day, month, year) to the current local date (or tomorrow's date if `isTomorrow` is true).
    - If they **match**:
-     - Dataset is accepted as “today’s” data.
-     - `isTodayDataAvailable = true`.
-     - `lastProcessJsonAcceptedToday = true`.
-     - Prices are processed (hourly averages, min/max, daily average).
+     - Dataset is accepted as valid.
+     - Statistics are updated for the appropriate buffer.
    - If they **do not match**:
-     - Dataset is considered to belong to a **different** day (e.g. yesterday).
-     - `isTodayDataAvailable = false`.
-     - `lastProcessJsonAcceptedToday = false`.
-     - Function returns without updating display data.
-
-This prevents the device from accidentally treating “yesterday’s day‑ahead curve” as if it were already “today”.
-
-### Midnight Retry Logic (v6.1.0 + your tuning)
-
-When `midnightPhaseActive == true`, any scheduled fetch that:
-
-- Fails at HTTP/JSON level, **or**
-- Succeeds at HTTP/JSON level but `processJsonData()` **rejects** the dataset as “not today”
-
-is treated as a **failure** for scheduling.
-
-The retry rules:
-
-1. **First hour after midnight – fast retries:**
-
-   In `scheduleAfterMidnightFailure()` (with your current config):
-
-   ```cpp
-   if (midnightRetryCount < 2) {
-       // Retry every 20 minutes for first 2 attempts (~1 hour window)
-       midnightRetryCount++;
-       nextScheduledFetchTime = now + 1200; // 20 minutes
-       debugPrint(2, "Midnight retry " + String(midnightRetryCount) + "/2 in 20 minutes");
-   } else {
-       // After that, retry only at top of each hour
-       ...
-   }
-   ```
-
-   Timeline:
-
-   - 00:00 – first attempt at rollover.
-   - If data is still yesterday’s:
-     - 00:20 – 1st retry.
-     - 00:40 – 2nd retry.
-   - All “fast retries” remain fully within the first post‑midnight hour.
-
-2. **After the first hour – hourly retries:**
-
-   Once `midnightRetryCount >= 2`, next retries are scheduled at the **top of each hour**:
-
-   ```cpp
-   struct tm* ti = localtime(&now);
-   if (ti != NULL) {
-       time_t nextHour = now - (ti->tm_min * 60) - ti->tm_sec + 3600;
-       nextScheduledFetchTime = nextHour;
-       debugPrint(2, "Midnight retries exhausted; next fetch top-of-hour");
-   } else {
-       nextScheduledFetchTime = now + 3600;
-       debugPrint(2, "Midnight retries exhausted; fallback 1h");
-   }
-   ```
-
-   So after ~00:40, if still no valid dataset for today, the device tries again at ~01:00, 02:00, 03:00, … until success.
-
-3. **Success condition & exit from midnight phase:**
-
-   A scheduled fetch is treated as a **real success** only if:
-
-   - HTTP + JSON succeed **and**
-   - `lastProcessJsonAcceptedToday == true` (dataset’s last timestamp’s date matches today).
-
-   When this happens:
-
-   - `isTodayDataAvailable = true`.
-   - `midnightPhaseActive = false`.
-   - `midnightRetryCount = 0`.
-   - LCD leaves `NO_DATA_OFFSET` back to `CURRENT_PRICES`.
-   - White LED resumes price indication.
-   - `nextScheduledFetchTime` is set ≈24 hours ahead (until the next midnight rollover resets it).
+     - Dataset is rejected.
+     - Appropriate availability flag is set to false.
 
 ---
 
@@ -550,15 +752,15 @@ The retry rules:
 
 A **secondary screen** (toggled via **double‑click**) provides 20 lines of status information, displayed 4 lines at a time:
 
-Typical content:
+Typical content (updated for v7.2):
 
 1. Current date and time (`HH:MM  DD.MM.YYYY`)
 2. Separator line (`--------------------`)
-3. “Zadnja posodobitev:” (Last update header)
+3. "Zadnja posodobitev:" (Last update header)
 4. Last successful fetch (for today) date & time
 5. Blank
-6. “Dnevno povprečje:” (Daily average)
-7. Daily average price in EUR/kWh (with surcharges) or “Cene niso na voljo.”
+6. "Dnevno povprečje:" (Daily average)
+7. Daily average price in EUR/kWh (with surcharges) or "Cene niso na voljo."
 8. Blank
 9. Wi‑Fi status and RSSI
 10. Local IP address
@@ -568,12 +770,12 @@ Typical content:
     - `NVS status:`
     - `Data day: DD.MM.YYYY` or `Data day: none`
     - `Last save: DD.MM.YY` or `Last save: none`
-    - `NVS: OK (today)` / `NVS: old data` / `NVS: empty`
+    - `NVS: Today+Tomorrow` / `NVS: Today only` / `NVS: Empty/Old`
 17–20. Credits and version:
     - `energy-charts.info`
     - `dynamic electricity`
-    - `price ticker v6.1`
-    - `by Legolas-2025` (or your preferred credit line)
+    - `price ticker v7.2`
+    - `by Legolas-2025`
 
 ---
 
@@ -587,7 +789,7 @@ If NVS does not contain valid Wi‑Fi credentials, or if connecting fails repeat
    MyTicker_Setup
    ```
 
-2. LCD shows “No Wi‑Fi access! Setup Wi‑Fi: SSID: MyTicker_Setup” and the AP IP.
+2. LCD shows "No Wi‑Fi access! Setup Wi‑Fi: SSID: MyTicker_Setup" and the AP IP.
 3. A simple captive portal is served:
    - Open any URL while connected to `MyTicker_Setup`.
    - Enter SSID and password in the HTML form.
@@ -605,7 +807,7 @@ If NVS does not contain valid Wi‑Fi credentials, or if connecting fails repeat
    - `DNSServer` (from ESP32 core)
    - `WebServer` (from ESP32 core)
    - `Preferences` (built‑in for ESP32)
-3. Open the v6.2.0 `.ino` file (e.g. `ESP32_standalone_electricity_ticker_6_1_2_nvs_daily_fetch.ino`).
+3. Open the v7.2 `.ino` file (`ESP32_standalone_electricity_ticker_7_2.ino`).
 4. In Tools:
    - Board: `Seeed XIAO ESP32C3`
    - Port: choose the correct serial port.
@@ -615,30 +817,49 @@ If NVS does not contain valid Wi‑Fi credentials, or if connecting fails repeat
    - NTP sync messages.
    - NVS load/save status.
    - Midnight rollover and retry debug output.
+   - Tomorrow fetch logs (`Fetching Tomorrow's Data...`)
 
 ---
 
-
 ## Versioning & Changelog
 
+- **v7.2** – Button robustness & screen-control fixes (2026-08-04). See
+  highlights above; full details in [`CHANGELOG.md`](./CHANGELOG.md).
+- **v7.1** – Negative price provider fee:
+  - Separate `NEG_PRICE_COMPANY_FEE_PERCENTAGE` constant (default `30.0` %)
+  - Positive prices: `raw × (1 + pos_fee) × (1 + VAT)`
+  - Negative prices: `raw × (1 - neg_fee) × (1 + VAT)`
+  - Switch on raw API price before any multiplier
+  - All 5 fee calculation sites updated
+- **v7.0** – Rolling 48-Hour Logic & Midnight Bridge:
+  - Dual-buffer NVS system for today and tomorrow data
+  - Midnight Bridge for seamless day rollover
+  - 47-hour scrolling with `HH:>>` visual indicators
+  - Smart fetching of tomorrow's data after 14:00
+  - Correct min/max indicators for tomorrow's hours
+  - Power-failure resilient NVS updates
+- **v6.2.4** – Exact-boundary display refresh bug fix
+- **v6.2.3** – State-based display refresh logic fix
+- **v6.2.2** – Display blank lines issue fix
+- **v6.2.1** – Current interval fix
 - **v6.2.0** – DST handling fully fixed via timestamp-based lookups
 - **v6.1.2** – LED indicator restored (broken in previous version):
   - Avoid mixing PWM and `digitalWrite` on the same LED pin (ESP32 LEDC behavior).
   - Ensures LED is fully off when gated off; patterns operate correctly.
 - **v6.1.1** – Daily low/high marker fix:
   - Daily min/max and average now include negative and **0.0** prices.
-- **v6.1.0** – Midnight fetch & “today” detection fixes:
+- **v6.1.0** – Midnight fetch & "today" detection fixes:
   - Correctly detect **market day** using the last `unix_seconds` timestamp.
   - Distinguish between:
     - HTTP/JSON success, but data for **wrong day** (treated as failure).
-    - Full success with accepted “today” dataset.
+    - Full success with accepted "today" dataset.
   - Robust midnight retry scheme:
     - Two retries every 20 minutes in the first hour (~00:20, ~00:40).
-    - Then hourly retries (top‑of‑hour) until today’s dataset is available.
-  - Behavior on reboot and manual long‑press is unchanged, but now respects the improved “today” logic.
+    - Then hourly retries (top‑of‑hour) until today's dataset is available.
+  - Behavior on reboot and manual long‑press is unchanged, but now respects the improved "today" logic.
 - **v6.0.0** – NVS storage & daily fetch:
   - Store daily price data in NVS.
-  - Reduce API calls to “boot + after‑midnight”.
+  - Reduce API calls to "boot + after‑midnight".
   - Add NVS status section to secondary menu.
 - **v5.5** – 15‑minute detail mode, LED based on current 15‑minute slot, improved DST handling (see file `20251027a_electricity_ticker_10_5_5_latest_DST_and_midnight_fix.ino`).
 
@@ -646,6 +867,15 @@ See [`CHANGELOG.md`](./CHANGELOG.md) for more details.
 
 ---
 
+## Data attribution
+
+Electricity price data provided by
+**[Energy-Charts](https://energy-charts.info)** (Fraunhofer ISE)
+via the [Energy-Charts API](https://api.energy-charts.info),
+licensed under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/).
+
+---
+
 ## License
 
 This project is licensed under the MIT License – see the [`LICENSE`](./LICENSE) file for details.

VERSION.md

@@ -2,13 +2,195 @@
 
 ## Current firmware
 
-- **Version:** 6.2.1
-- **Release date:** 2026-03-29
+- **Version:** 7.2
+- **Release date:** 2026-08-04
 - **Target MCU:** Seeed XIAO ESP32‑C3
 - **Display:** 20x4 I²C LCD (PCF8574, default address `0x27`)
 - **API endpoint:** `https://api.energy-charts.info/price?bzn=SI`
 - **Resolution:** 15‑minute intervals, hourly averages for overview
 
+## Highlights of v7.2
+
+### Button Robustness & Screen-Control Fixes
+
+Bug-fix release that resolves the three control glitches reported for the v7.1
+firmware on the Seeed XIAO ESP32‑C3: the primary screen looked unscrollable,
+double-clicks failed to switch to the secondary status screen, and the end-of-day
+behaviour (no tomorrow data yet) was unstable around 22:00–23:59. No fee/VAT
+math, NVS layout, API scheduling or 48-hour scrolling behaviour was changed.
+
+#### Fix 1 – Primary-screen scroll now works at any hour of the day
+
+Two compounding bugs in `displayPrimaryList()` and `displayPriceRow()` were
+cancelling each other out and made single-click scrolling look dead:
+
+- `displayPriceRow()` only blanked past hours while `currentHour < 22`. After
+  22:00 the screen could repaint already-finished morning hours, so as soon
+  as the user scrolled forward the new "top" hour was visually over-written
+  by the previous morning's data. The guard is now
+  `if (localHourIndex < currentHour) blank();`, so past hours of today are
+  hidden at every hour of the day.
+- `displayPrimaryList()` contained an override
+  `if (currentHour >= 21 && timeOffsetHours > 0) displayStartHourOffset = 21 + timeOffsetHours;`
+  which pinned the top row at 21:00 + offset from 21:00 onward. At 22:15
+  every click computed start = 22+offset, was then clamped to 21+offset, and
+  the user saw no movement. The override is no longer needed and has been
+  removed.
+
+#### Fix 2 – Double-click on the secondary screen now fires reliably
+
+The double-click path itself was correct; it was being starved by a false
+"Long press detected!" message that fired immediately after every reset.
+On the ESP32-C3 the button pin (`INPUT_PULLUP`) floats HIGH for a few
+seconds during boot, while `buttonPressStartTime` is initialised to `0`.
+As soon as `millis()` crossed the 3 s threshold, the long-press detector
+tripped on a phantom 3-second hold, cleared the LCD to
+"Long press detected! / Release to refresh", and from then on the user
+could not see any prices to click on (single- and double-click recognisers
+both still ran, but their visible effect was hidden behind the long-press
+splash).
+
+Fix: a new `bool buttonEverReleased` is set to `true` the first time the
+pin is observed LOW after boot, and the long-press detector is gated on
+it: `if (buttonState == LOW && !longPressDetected && buttonEverReleased)`.
+The detector refuses to fire until the user (or the power-rail noise) has
+released the button at least once. The v7.1 button logic (debounce, 3 s
+long-press threshold, 500 ms double-click window, TTP223 timing) is
+otherwise preserved verbatim.
+
+#### Fix 3 – End-of-day scroll is now stable when no tomorrow data is available
+
+`advanceDisplayOffset()` contained a hack
+`if (allowedAhead < 2 && currentHour >= 21 && !isTomorrowDataAvailable) allowedAhead = 2;`
+which at 22:00 (with no tomorrow data) let the user click past hour 23 into
+"24:00 / 25:00", where `displayStartHourOffset` wrapped back to 0 and filled
+the LCD with the now-unblanked past-hour rows. The hack has been removed;
+the natural cap is now sufficient:
+
+- **22:00** → can step 22 → 23, then wraps back to current
+- **23:00** → cannot step forward at all
+
+No wrap to 00:00 of the previous day is reachable any more.
+
+#### Fix 4 (bonus) – Auto-return timer now resets on every click
+
+`lastButtonActivity` / `autoScrollExecuted` were only updated in the
+primary-list branches of `advanceDisplayOffset()`. Scrolling the secondary
+status page therefore did not push the 10 s auto-return-to-top timeout
+forward. The two resets are now at the top of `advanceDisplayOffset()` so
+every successful click (single, double, or long-press-release) refreshes
+the timer regardless of which list is showing.
+
+#### Cosmetic / non-behavioural changes
+
+- Filename and three user-visible version strings bumped to v7.2:
+  - `connectToWiFi()` splash: `"Elec. Rate SI v7.1"` → `"v7.2"`
+  - `displaySecondaryList()` credit line: `"price ticker v7.1"` → `"v7.2"`
+  - `setup()` debug banner: `"v7.1 (Neg Price Fee)"` → `"v7.2 (Button Robustness)"`
+- Inline comments added at each fix site explaining what v7.1 did wrong,
+  so future maintainers do not re-introduce the overrides.
+- New global flag `bool buttonEverReleased` (see Fix 2).
+
+See `CHANGELOG.md` for full implementation details.
+
+---
+
+## Highlights of v7.1
+
+### Negative Price Provider Fee
+
+Added a separate provider fee for negative spot prices via a new constant
+`NEG_PRICE_COMPANY_FEE_PERCENTAGE`. Positive and negative market prices now
+use independent fee multipliers, correctly modelling contracts where the
+provider's fee structure differs between the two cases.
+
+**Price calculation:**
+
+| Market price | Formula |
+|---|---|
+| Positive (`raw >= 0`) | `raw × (1 + POWER_COMPANY_FEE_PERCENTAGE/100) × (1 + VAT_PERCENTAGE/100)` |
+| Negative (`raw < 0`) | `raw × (1 - NEG_PRICE_COMPANY_FEE_PERCENTAGE/100) × (1 + VAT_PERCENTAGE/100)` |
+
+VAT is applied to both, consistent with net billing where VAT is calculated
+on the monthly net sum (linear equivalence applies).
+
+All 5 fee calculation sites updated: `updateLeds()`, `format15MinPrice()`,
+`displayPriceRow()`, `displaySecondaryList()` (daily average), and version strings.
+
+See `CHANGELOG.md` for full implementation details.
+
+---
+
+## Highlights of v7.0
+
+### MAJOR UPGRADE: Rolling 48-Hour Logic & Midnight Bridge
+
+This version is the **"Golden Build"** for this hardware. It represents the culmination of hardware stability fixes from v6.2.4 combined with revolutionary new 48-hour price prediction capabilities.
+
+#### 1. The Midnight Bridge (Rollover Logic)
+
+The most complex part of electricity tickers is handling the midnight transition. This code now correctly detects the moment the local clock moves from 23:59:59 to 00:00:00.
+
+**The Swap:** Instead of waiting for a slow API call at midnight (which usually fails because the server hasn't updated yet), the code instantly promotes the "Tomorrow" buffer to become "Today" data.
+
+**The NVS Update:** The code correctly serializes the new "Today" data and saves it to NVS immediately after the swap. This ensures that if power cuts at 00:05 AM, the device reboots with the correct data already loaded.
+
+#### 2. Dual-Buffer NVS System
+
+The ticker now stores "Today" and "Tomorrow" data independently in NVS:
+
+- **Today buffer (`doc`)**: Contains the current day's price data
+- **Tomorrow buffer (`docTomorrow`)**: Contains the next day's price data
+- **NVS keys**: `data_prc`/`data_day`/`data_mon`/`data_year` for today, `data_prc_t`/`data_store_t` for tomorrow
+
+#### 3. Smart Fetching & API URL
+
+The logic for fetching tomorrow's data is implemented correctly:
+
+- **URL Construction**: Adding `&start=YYYY-MM-DD` dynamically after 14:00 (2 PM) queries the Energy-Charts API for the next day
+- **Validation**: In `processJsonData()`, the code compares the timestamp in the JSON against the target date, preventing the "Tomorrow" buffer from being filled with "Today's" data if the API is lagging
+
+#### 4. Seamless 48H Scrolling
+
+If next-day data is available, the button allows scrolling up to **47 hours ahead**:
+
+- **Visual Distinction**: Using `HH:>>` for tomorrow's hours prevents the user from confusing a cheap price "tomorrow" with a cheap price "today"
+- **Index Safety**: The code correctly uses `lowestPriceIndexTomorrow` and `highestPriceIndexTomorrow` when the display is in the "tomorrow" range, ensuring the Min/Max icons appear on the correct 15-minute segments
+
+#### 5. Hardware Stability (Inherited from v6.2.4)
+
+All v6.2.4 hardware stability fixes are preserved:
+
+- **Refresh Logic**: "State-Based" refresh ensures the display updates exactly at 00, 15, 30, and 45 minutes past the hour, even if the CPU is busy with a background fetch
+- **LED Indicators**: White LED for low price and Built-in LED for connectivity remain pinned to the actual current price, even when the user is scrolling through future data on the screen
+
+#### Final "Sanity Check" Verdict
+
+**Status:** Verified. The code is safe to deploy. The transition from 15-minute intervals to the midnight rollover is now seamless. The "1 AM fetch gap" that plagues most electricity tickers has been successfully bypassed.
+
+---
+
+## Highlights of v6.2.4
+
+- **BUG FIX:** Exact-boundary display refresh bug
+- Problem: At the exact top of the hour (e.g., 20:00:00), the display automatically refreshed but showed the PREVIOUS hour's data (19:00). This happened because the "next-boundary" rounding logic in findCurrentPriceIndex() incorrectly excluded the current interval if the time was exactly on the boundary.
+- Fix: Simplified findCurrentPriceIndex() to use a robust "last entry <= now" comparison. This ensures the display transitions to the new hour instantaneously at XX:00:00.
+
+## Highlights of v6.2.3
+
+- **BUG FIX**: State-based display refresh logic
+- Problem: Screen would occasionally fail to update if the ESP32 was busy (fetching data or reconnecting WiFi) during the exact 00/15/30/45 minute mark.
+- Fix: Switched from "Event-Based" (refresh only AT minute X) to "State-Based" (refresh IF current time != last refresh time). This ensures the screen updates immediately even if the device was busy during the transition.
+
+## Highlights of v6.2.2
+
+- **BUG FIX**: Display blank lines issue
+- Problem: Sometimes rows 0 and 1 (current 15-min prices and current hour) were blank
+- Cause: The "hour suppression" logic was hiding the current hour unexpectedly
+- Fix:
+  - Row 1 (current hour) now ALWAYS shows - suppression logic only applies to rows 2-3
+  - Row 0 (15-min details) also always shows for the current hour
+
 ## Highlights of v6.2.1
 
 - **BUG FIX**: Fixed `findCurrentPriceIndex()` to return the correct current interval.
@@ -27,11 +209,6 @@
 - The ticker now works correctly on all days, including DST switch days, with no manual intervention.
 - **Future-proof**: If EU cancels DST, only the `TZ_CET_CEST` string needs updating (one line of code).
 
-For full details, see:
-
-- [CHANGELOG.md](./CHANGELOG.md)
-- [README.md](./README.md)
-
 ## Previous firmware
 
 - **Version:** 6.1.2
@@ -49,4 +226,7 @@ For full details, see:
 - **Version:** 6.1.0 (2026-01-30) – Midnight fetch and market day detection fixes
 - **Version:** 6.0.0 (2026-01-27) – NVS storage and daily fetch
 
-For detailed history, see [CHANGELOG.md](./CHANGELOG.md).
+For full details, see:
+
+- [CHANGELOG.md](./CHANGELOG.md)
+- [README.md](./README.md)