Extend pinGuard validation to prevent duplicate pin use

Docs/Commands.md

@@ -59,6 +59,7 @@ These are commands used to configure the system settings and can only be sent fr
 | `F12` — OTA Check / Apply | `F12` or `F12:apply=1` | Trigger an OTA firmware check against the latest GitHub release. Without params (or `apply=0`) checks only and returns current status. With `apply=1` downloads and applies the update if one is available (or queues apply if a check is already in progress). Response params: `v=<current>` current firmware version, `av=<available>` available version tag (empty if none found yet), `s=<state>` OTA state string. **PCH only** — requires `OTA_AUTO_UPDATE`, ESP32 and WiFi in client mode. |
 | `F13` — OTA Status | `F13` | Query current OTA state without triggering a check. Response params: `v=<current>` current firmware version, `av=<available>` available version tag, `s=<state>` OTA state string (`idle`, `checking`, `available`, `downloading`, `rebooting`, `failed`, `uptodate`), `auto=<0\|1>` whether auto-apply is enabled. **PCH only** — requires `OTA_AUTO_UPDATE`, ESP32 and WiFi in client mode. |
 | `F14` — PinGuard Mode | `F14` or `F14:a=true` or `F14:a=false;b=false` | Read or write the persistent PinGuard mode flags stored in `SystemHeader::pinGuardFlags`. **Params:** `a=<bool>` — AllowAdvisory: when `true`, advisory (strapping/UART) pins are permitted. `b=<bool>` — Bypass: when `true`, all PinGuard checks are skipped (no validation at all). If both `a` and `b` are `true`, Bypass takes precedence and the system returns `Safe` immediately. Changes are persisted immediately via `saveHeader()` and take effect at runtime without reboot. **Response:** `a=<0\|1>` current AllowAdvisory state, `b=<0\|1>` current Bypass state. No params = read-only. |
+| `F15` — Pin Usage | `F15` | Returns a list of all GPIO pins currently assigned in configuration. Pins set to `0xFF` (disabled / not fitted) are omitted. **Serial response:** `v=pin1,pin2,...` (single frame). **WiFi response:** JSON object with a `pins` array. No params. |
 
 
 **OTA behaviour (F12 / F13):**

PowerControlHub/PinGuard.h

@@ -46,6 +46,7 @@
 
 #include <stdint.h>
 #include "SystemDefinitions.h"
+#include "SystemFunctions.h"
 
 // ─── Pin Use ─────────────────────────────────────────────────────────────────
 // Describes the intended use of a pin.  Input-only GPIO are fine for Input,
@@ -65,28 +66,29 @@ enum class PinUse : uint8_t
 // ─── Pin Category ─────────────────────────────────────────────────────────────
 enum class PinCategory : uint8_t
 {
-	Safe     = 0,   // unrestricted
+	Safe = 0,   // unrestricted
 	Advisory = 1,   // risky; behaviour governed by PinGuardMode
-	Hard     = 2,   // always rejected for the given use
+	Hard = 2,   // always rejected for the given use
 };
 
 // ─── Validation Result ────────────────────────────────────────────────────────
 enum class PinGuardResult : uint8_t
 {
-	Safe            = 0,    // pin is fine for the requested use
+	Safe = 0,    // pin is fine for the requested use
 	AdvisoryBlocked = 1,    // advisory pin blocked (mode does not permit advisory)
-	HardBlocked     = 2,    // hard-blocked — must not be used for this purpose
-	Disabled        = 3,    // pin == PinDisabled (0xFF) — treated as not fitted
+	HardBlocked = 2,    // hard-blocked — must not be used for this purpose
+	Disabled = 3,    // pin == PinDisabled (0xFF) — treated as not fitted
+	InUse = 4,    // pin is already in use by another configured function
 };
 
 // ─── PinGuard Mode ────────────────────────────────────────────────────────────
 // Persistent system setting stored in SystemHeader::pinGuardFlags.
 // Configured via the F14 command.
 namespace PinGuardMode
 {
-	constexpr uint8_t None         = 0x00;  // strict — advisory pins are blocked
+	constexpr uint8_t None = 0x00;  // strict — advisory pins are blocked
 	constexpr uint8_t AllowAdvisory = 0x01; // advisory pins are permitted
-	constexpr uint8_t Bypass        = 0x02; // skip all checks — always returns Safe
+	constexpr uint8_t Bypass = 0x02; // skip all checks — always returns Safe
 }
 
 // ─── Internal helpers — not for direct use ───────────────────────────────────
@@ -113,8 +115,8 @@ namespace PinGuardInternal
 
 struct PinTableEntry
 {
-	uint8_t      gpio;
-	PinCategory  category;
+	uint8_t gpio;
+	PinCategory category;
 };
 
 #if defined(CONFIG_IDF_TARGET_ESP32S3)
@@ -224,7 +226,7 @@ class PinGuard
 	 */
 	static bool isBlocked(PinGuardResult result)
 	{
-		return result == PinGuardResult::HardBlocked || result == PinGuardResult::AdvisoryBlocked;
+		return result == PinGuardResult::HardBlocked || result == PinGuardResult::AdvisoryBlocked || result == PinGuardResult::InUse;
 	}
 
 	/**
@@ -244,6 +246,10 @@ class PinGuard
 		if (pin == PinDisabled)
 			return PinGuardResult::Disabled;
 
+		// Check whether this pin is already assigned elsewhere in the configuration
+		if (SystemFunctions::pinInUse(pin))
+			return PinGuardResult::InUse;
+
 		// Bypass: skip all checks
 		if (_mode & PinGuardMode::Bypass)
 			return PinGuardResult::Safe;
@@ -309,6 +315,8 @@ class PinGuard
 				return F("advisory (strapping/UART pin)");
 			case PinGuardResult::Disabled:
 				return F("disabled (255)");
+			case PinGuardResult::InUse:
+				return F("in use (already configured)");
 			default:
 				return F("safe");
 		}