From f5592595bccf12ebc89777959b389fd4a2949575 Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw2@infradead.org>
Date: Mon, 15 Dec 2025 23:22:23 +0000
Subject: [PATCH] Use fnv1a_hash_extend with config_hash and version for sensor
 baselines

Change sen5x, sgp30, and sgp4x components to use fnv1a_hash_extend()
starting with config_hash and ESPHOME_VERSION, then extending with the
sensor serial number. This replaces the previous use of fnv1_hash with
compilation_time.

This ensures baseline storage is invalidated on config or version
changes, not just on recompilation.
---
 esphome/components/sen5x/sen5x.cpp | 8 +++++---
 esphome/components/sgp30/sgp30.cpp | 7 ++++---
 esphome/components/sgp4x/sgp4x.cpp | 8 +++++---
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/esphome/components/sen5x/sen5x.cpp b/esphome/components/sen5x/sen5x.cpp
index ffb9e2bc02..1a09cc6bc1 100644
--- a/esphome/components/sen5x/sen5x.cpp
+++ b/esphome/components/sen5x/sen5x.cpp
@@ -1,4 +1,5 @@
 #include "sen5x.h"
+#include "esphome/core/application.h"
 #include "esphome/core/hal.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
@@ -154,10 +155,11 @@ void SEN5XComponent::setup() {
       if (this->voc_sensor_ && this->store_baseline_) {
         uint32_t combined_serial =
             encode_uint24(this->serial_number_[0], this->serial_number_[1], this->serial_number_[2]);
-        // Hash with compilation time and serial number
+        // Hash with config hash, version, and serial number
         // This ensures the baseline storage is cleared after OTA
-        // Serial numbers are unique to each sensor, so mulitple sensors can be used without conflict
-        uint32_t hash = fnv1_hash(App.get_compilation_time_ref() + std::to_string(combined_serial));
+        // Serial numbers are unique to each sensor, so multiple sensors can be used without conflict
+        uint32_t hash = fnv1a_hash_extend(App.get_config_hash(), ESPHOME_VERSION);
+        hash = fnv1a_hash_extend(hash, std::to_string(combined_serial));
         this->pref_ = global_preferences->make_preference<Sen5xBaselines>(hash, true);
 
         if (this->pref_.load(&this->voc_baselines_storage_)) {
diff --git a/esphome/components/sgp30/sgp30.cpp b/esphome/components/sgp30/sgp30.cpp
index fa548ce94e..83ffbda457 100644
--- a/esphome/components/sgp30/sgp30.cpp
+++ b/esphome/components/sgp30/sgp30.cpp
@@ -72,10 +72,11 @@ void SGP30Component::setup() {
     return;
   }
 
-  // Hash with compilation time and serial number
+  // Hash with config hash, version, and serial number
   // This ensures the baseline storage is cleared after OTA
-  // Serial numbers are unique to each sensor, so mulitple sensors can be used without conflict
-  uint32_t hash = fnv1_hash(App.get_compilation_time_ref() + std::to_string(this->serial_number_));
+  // Serial numbers are unique to each sensor, so multiple sensors can be used without conflict
+  uint32_t hash = fnv1a_hash_extend(App.get_config_hash(), ESPHOME_VERSION);
+  hash = fnv1a_hash_extend(hash, std::to_string(this->serial_number_));
   this->pref_ = global_preferences->make_preference<SGP30Baselines>(hash, true);
 
   if (this->store_baseline_ && this->pref_.load(&this->baselines_storage_)) {
diff --git a/esphome/components/sgp4x/sgp4x.cpp b/esphome/components/sgp4x/sgp4x.cpp
index a0c957d608..9929986eb8 100644
--- a/esphome/components/sgp4x/sgp4x.cpp
+++ b/esphome/components/sgp4x/sgp4x.cpp
@@ -1,4 +1,5 @@
 #include "sgp4x.h"
+#include "esphome/core/application.h"
 #include "esphome/core/log.h"
 #include "esphome/core/hal.h"
 #include <cinttypes>
@@ -56,10 +57,11 @@ void SGP4xComponent::setup() {
   ESP_LOGD(TAG, "Version 0x%0X", featureset);
 
   if (this->store_baseline_) {
-    // Hash with compilation time and serial number
+    // Hash with config hash, version, and serial number
     // This ensures the baseline storage is cleared after OTA
-    // Serial numbers are unique to each sensor, so mulitple sensors can be used without conflict
-    uint32_t hash = fnv1_hash(App.get_compilation_time_ref() + std::to_string(this->serial_number_));
+    // Serial numbers are unique to each sensor, so multiple sensors can be used without conflict
+    uint32_t hash = fnv1a_hash_extend(App.get_config_hash(), ESPHOME_VERSION);
+    hash = fnv1a_hash_extend(hash, std::to_string(this->serial_number_));
     this->pref_ = global_preferences->make_preference<SGP4xBaselines>(hash, true);
 
     if (this->pref_.load(&this->voc_baselines_storage_)) {