feat(core): introduce telemetry

diff --git a/core/SConscript.bootloader b/core/SConscript.bootloader
index cbc70211..b85086ee 100644
--- a/core/SConscript.bootloader
+++ b/core/SConscript.bootloader
@@ -27,6 +27,7 @@ FEATURES_WANTED = [
     "secure_domain",
     "secure_mode",
     "suspend",
+    "telemetry",
     "usb",
     "usb_iface_wire",
     ]
diff --git a/core/SConscript.kernel b/core/SConscript.kernel
index a310a10c..2e2ebe2d 100644
--- a/core/SConscript.kernel
+++ b/core/SConscript.kernel
@@ -60,6 +60,7 @@ FEATURES_WANTED = [
     "smp",
     "storage",
     "suspend",
+    "telemetry",
     "tropic",
     "usb",
     "usb_iface_wire",
diff --git a/core/SConscript.secmon b/core/SConscript.secmon
index 130ce7b4..ee99f936 100644
--- a/core/SConscript.secmon
+++ b/core/SConscript.secmon
@@ -43,6 +43,7 @@ FEATURES_WANTED = [
     "secure_mode",
     "storage",
     "suspend",
+    "telemetry",
     "tropic",
     "nrf_auth"
     ]
diff --git a/core/embed/sys/backup_ram/inc/sys/backup_ram.h b/core/embed/sys/backup_ram/inc/sys/backup_ram.h
index af0eadbb..33683afe 100644
--- a/core/embed/sys/backup_ram/inc/sys/backup_ram.h
+++ b/core/embed/sys/backup_ram/inc/sys/backup_ram.h
@@ -24,6 +24,7 @@
 /** Global keys for items stored in the backup RAM */
 #define BACKUP_RAM_KEY_PM_RECOVERY 0x0001   // Power management recovery data
 #define BACKUP_RAM_KEY_BLE_SETTINGS 0x0002  // BLE settings
+#define BACKUP_RAM_KEY_TELEMETRY 0x0003  // Telemetry data (min/max temps etc.)
 
 /** Maximum size of data stored under a single key in backup RAM */
 #define BACKUP_RAM_MAX_KEY_DATA_SIZE 512
diff --git a/core/embed/sys/power_manager/stm32u5/power_monitoring.c b/core/embed/sys/power_manager/stm32u5/power_monitoring.c
index f708c80e..34a92828 100644
--- a/core/embed/sys/power_manager/stm32u5/power_monitoring.c
+++ b/core/embed/sys/power_manager/stm32u5/power_monitoring.c
@@ -25,6 +25,10 @@
 #include <sys/systick.h>
 #include <trezor_rtl.h>
 
+#ifdef USE_TELEMETRY
+#include <util/telemetry.h>
+#endif
+
 #include "../fuel_gauge/battery_model.h"
 #include "../fuel_gauge/fuel_gauge.h"
 #include "../stwlc38/stwlc38.h"
@@ -77,6 +81,11 @@ void pm_pmic_data_ready(void* context, pmic_report_t* report) {
   // Get wireless charger data
   stwlc38_get_report(&drv->wireless_data);
 
+#ifdef USE_TELEMETRY
+  // Update telemetry with current battery temperature
+  telemetry_update_battery_temp(drv->pmic_data.ntc_temp);
+#endif
+
   pm_parse_power_source_state(drv);
 
   // Run battery charging controller
diff --git a/core/embed/sys/smcall/stm32/smcall_dispatch.c b/core/embed/sys/smcall/stm32/smcall_dispatch.c
index b5f5d728..22c1bf5a 100644
--- a/core/embed/sys/smcall/stm32/smcall_dispatch.c
+++ b/core/embed/sys/smcall/stm32/smcall_dispatch.c
@@ -403,6 +403,27 @@ __attribute((no_stack_protector)) void smcall_handler(uint32_t *args,
     } break;
 #endif  // USE_BACKUP_RAM
 
+#ifdef USE_TELEMETRY
+    // ------------------------------------------------------------------
+    // Telemetry
+    case SMCALL_TELEMETRY_UPDATE_BATT_TEMP: {
+      union {
+        float f;
+        uint32_t u;
+      } u32_to_float = {.u = args[0]};
+
+      float temp = u32_to_float.f;
+      telemetry_update_battery_temp__verified(temp);
+    } break;
+
+    case SMCALL_TELEMETRY_GET_BATT_TEMP_MIN_MAX: {
+      float *out_min_c = (float *)args[0];
+      float *out_max_c = (float *)args[1];
+      args[0] =
+          telemetry_get_battery_temp_min_max__verified(out_min_c, out_max_c);
+    } break;
+#endif  // USE_TELEMETRY
+
     default:
       system_exit_fatal("Invalid smcall", __FILE__, __LINE__);
       break;
diff --git a/core/embed/sys/smcall/stm32/smcall_numbers.h b/core/embed/sys/smcall/stm32/smcall_numbers.h
index 6312b4c8..5fc3039a 100644
--- a/core/embed/sys/smcall/stm32/smcall_numbers.h
+++ b/core/embed/sys/smcall/stm32/smcall_numbers.h
@@ -104,4 +104,7 @@ typedef enum {
 
   SMCALL_SECRET_KEYS_GET_DELEGATED_IDENTITY_KEY,
 
+  SMCALL_TELEMETRY_UPDATE_BATT_TEMP,
+  SMCALL_TELEMETRY_GET_BATT_TEMP_MIN_MAX,
+
 } smcall_number_t;
diff --git a/core/embed/sys/smcall/stm32/smcall_stubs.c b/core/embed/sys/smcall/stm32/smcall_stubs.c
index 2f6a9460..2f854eed 100644
--- a/core/embed/sys/smcall/stm32/smcall_stubs.c
+++ b/core/embed/sys/smcall/stm32/smcall_stubs.c
@@ -407,4 +407,28 @@ secbool secret_validate_nrf_pairing(const uint8_t *message, size_t msg_len,
 
 #endif
 
+#ifdef USE_TELEMETRY
+
+// =============================================================================
+// telemetry.h
+// =============================================================================
+
+#include <util/telemetry.h>
+
+void telemetry_update_battery_temp(float temp_c) {
+  union {
+    float f;
+    uint32_t u;
+  } float_to_u32 = {.f = temp_c};
+
+  smcall_invoke1(float_to_u32.u, SMCALL_TELEMETRY_UPDATE_BATT_TEMP);
+}
+
+bool telemetry_get_battery_temp_min_max(float *out_min_c, float *out_max_c) {
+  return (bool)smcall_invoke2((uint32_t)out_min_c, (uint32_t)out_max_c,
+                              SMCALL_TELEMETRY_GET_BATT_TEMP_MIN_MAX);
+}
+
+#endif
+
 #endif  // defined(KERNEL) && defined(USE_SECMON_LAYOUT)
diff --git a/core/embed/sys/smcall/stm32/smcall_verifiers.c b/core/embed/sys/smcall/stm32/smcall_verifiers.c
index ab777c51..96872a5c 100644
--- a/core/embed/sys/smcall/stm32/smcall_verifiers.c
+++ b/core/embed/sys/smcall/stm32/smcall_verifiers.c
@@ -574,4 +574,30 @@ access_violation:
 
 #endif
 
+#ifdef USE_TELEMETRY
+#include <util/telemetry.h>
+
+// Telemetry verifiers
+void telemetry_update_battery_temp__verified(float temp_c) {
+  // No pointers to verify; simple value pass-through
+  telemetry_update_battery_temp(temp_c);
+}
+
+bool telemetry_get_battery_temp_min_max__verified(float *out_min_c,
+                                                  float *out_max_c) {
+  if (out_min_c && !probe_write_access(out_min_c, sizeof(*out_min_c))) {
+    goto access_violation;
+  }
+  if (out_max_c && !probe_write_access(out_max_c, sizeof(*out_max_c))) {
+    goto access_violation;
+  }
+
+  return telemetry_get_battery_temp_min_max(out_min_c, out_max_c);
+
+access_violation:
+  apptask_access_violation();
+  return false;
+}
+#endif  // USE_TELEMETRY
+
 #endif  // SECMON
diff --git a/core/embed/sys/smcall/stm32/smcall_verifiers.h b/core/embed/sys/smcall/stm32/smcall_verifiers.h
index eca1c646..bda3552d 100644
--- a/core/embed/sys/smcall/stm32/smcall_verifiers.h
+++ b/core/embed/sys/smcall/stm32/smcall_verifiers.h
@@ -164,4 +164,17 @@ secbool secret_validate_nrf_pairing__verified(const uint8_t *message,
                                               size_t mac_len);
 #endif
 
+#ifdef USE_TELEMETRY
+// ---------------------------------------------------------------------
+// Telemetry
+// ---------------------------------------------------------------------
+
+#include <util/telemetry.h>
+
+void telemetry_update_battery_temp__verified(float temp_c);
+
+bool telemetry_get_battery_temp_min_max__verified(float *out_min_c,
+                                                  float *out_max_c);
+#endif  // USE_TELEMETRY
+
 #endif  // SECMON
diff --git a/core/embed/util/telemetry/inc/util/telemetry.h b/core/embed/util/telemetry/inc/util/telemetry.h
new file mode 100644
index 00000000..aec62fb9
--- /dev/null
+++ b/core/embed/util/telemetry/inc/util/telemetry.h
@@ -0,0 +1,52 @@
+/*
+ * This file is part of the Trezor project, https://trezor.io/
+ *
+ * Copyright (c) SatoshiLabs
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <trezor_types.h>
+
+/**
+ * @brief Telemetry data structure.
+ */
+typedef struct {
+  float min_temp_c; /**< Minimum recorded battery temperature in Celsius. */
+  float max_temp_c; /**< Maximum recorded battery temperature in Celsius. */
+} telemetry_data_t;
+
+/**
+ * @brief Record current battery temperature (in Celsius) into telemetry
+ * storage.
+ *
+ * Updates persisted min/max values:
+ *  - minimum can only decrease
+ *  - maximum can only increase
+ *
+ * @param temp_c Current battery temperature in Celsius.
+ */
+void telemetry_update_battery_temp(float temp_c);
+
+/**
+ * @brief Retrieve stored min/max battery temperature (in Celsius).
+ *
+ * @param[out] out Pointer to where the telemetry data will be stored (may be
+ * NULL).
+ *
+ * @return true if values are available (initialized), false otherwise.
+ */
+bool telemetry_get(telemetry_data_t* out);
diff --git a/core/embed/util/telemetry/telemetry.c b/core/embed/util/telemetry/telemetry.c
new file mode 100644
index 00000000..842a9a60
--- /dev/null
+++ b/core/embed/util/telemetry/telemetry.c
@@ -0,0 +1,97 @@
+/*
+ * This file is part of the Trezor project, https://trezor.io/
+ *
+ * Copyright (c) SatoshiLabs
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifdef SECURE_MODE
+
+#include <trezor_types.h>
+
+#include <sys/backup_ram.h>
+
+#include <util/telemetry.h>
+
+// Versioning for persisted telemetry structure
+#define TELEMETRY_DATA_VERSION 0x0001
+
+typedef struct {
+  uint16_t version;
+  uint8_t initialized;  // 0 = not set, 1 = valid data present
+  uint8_t reserved;     // alignment/padding
+  telemetry_data_t data;
+} telemetry_t;
+
+static bool telemetry_read(telemetry_t* out) {
+  size_t size = 0;
+  if (!backup_ram_read(BACKUP_RAM_KEY_TELEMETRY, out, sizeof(*out), &size)) {
+    return false;
+  }
+  if (size != sizeof(*out)) {
+    return false;
+  }
+  if (out->version != TELEMETRY_DATA_VERSION) {
+    return false;
+  }
+  return true;
+}
+
+static bool telemetry_write(const telemetry_t* data) {
+  return backup_ram_write(BACKUP_RAM_KEY_TELEMETRY, BACKUP_RAM_ITEM_PUBLIC,
+                          data, sizeof(*data));
+}
+
+void telemetry_update_battery_temp(float temp_c) {
+  telemetry_t telemetry;
+  bool have = telemetry_read(&telemetry) && telemetry.initialized == 1;
+
+  if (!have) {
+    telemetry.version = TELEMETRY_DATA_VERSION;
+    telemetry.initialized = 1;
+    telemetry.reserved = 0;
+    telemetry.data.min_temp_c = temp_c;
+    telemetry.data.max_temp_c = temp_c;
+    telemetry_write(&telemetry);
+    return;
+  }
+
+  bool changed = false;
+  if (temp_c < telemetry.data.min_temp_c) {
+    telemetry.data.min_temp_c = temp_c;  // min can only decrease
+    changed = true;
+  }
+  if (temp_c > telemetry.data.max_temp_c) {
+    telemetry.data.max_temp_c = temp_c;  // max can only increase
+    changed = true;
+  }
+
+  if (changed) {
+    telemetry_write(&telemetry);
+  }
+}
+
+bool telemetry_get(telemetry_data_t* out) {
+  telemetry_t telemetry;
+  if (!telemetry_read(&telemetry) || telemetry.initialized != 1) {
+    return false;
+  }
+  if (out != NULL) {
+    *out = telemetry.data;
+  }
+  return true;
+}
+
+#endif
diff --git a/core/site_scons/models/T3W1/trezor_t3w1_revC.py b/core/site_scons/models/T3W1/trezor_t3w1_revC.py
index 0aed85e3..3c7e1caa 100644
--- a/core/site_scons/models/T3W1/trezor_t3w1_revC.py
+++ b/core/site_scons/models/T3W1/trezor_t3w1_revC.py
@@ -237,6 +237,11 @@ def configure(
         paths += ["embed/util/hw_revision/inc"]
         sources += ["embed/util/hw_revision/stm32/hw_revision.c"]
 
+    if "telemetry" in features_wanted:
+        sources += ["embed/util/telemetry/telemetry.c"]
+        paths += ["embed/util/telemetry/inc"]
+        defines += [("USE_TELEMETRY", "1")]
+
     defines += [
         "FRAMEBUFFER",
         "DISPLAY_RGBA8888",