feat: preserve normal radio profiles across event firmware (#11110)

* feat: isolate event radio profiles

* fix: preserve identity on degraded config boot

* fix: guard event profile storage

* style: align event profile storage names

* fix: discard event profile on normal boot

* refactor: simplify event profile cleanup

* fix: limit inactive profile migration to event firmware

* fix(event): make event-profile capacity check portable across filesystems

The USERPREFS_EVENT_MODE storage preflight called FSCom.totalBytes() and
FSCom.usedBytes(), which only exist on ESP32's LittleFS wrapper. Every other
backend failed to compile once event mode was enabled:

  error: 'class InternalFileSystem' has no member named 'totalBytes'   (nRF52)
  error: no member named 'totalBytes' in 'fs::FS'                      (Portduino)

This was not caught earlier because the event block is behind
#if USERPREFS_EVENT_MODE, and the existing unit tests only cover the pure
helpers, which compile identically either way.

Add fsTotalBytes()/fsUsedBytes() to FSCommon and implement them per backend:
littlefs v1 traversal for nRF52 (Adafruit_LittleFS) and STM32
(STM32_LittleFS), FSInfo for RP2040, statvfs for Portduino, and the native
methods for ESP32 and nRF54L15. The nRF52/STM32 path reports "full" if the
traversal errors so the capacity check fails safe.

Verified with USERPREFS_EVENT_MODE=1: native-macos test_event_profile_storage
passes 5/5, and heltec-v3, rak4631, rak11310 and rak3172 all build clean.

* fix(event): use std::filesystem for Portduino capacity, bump native-suite-count

Two CI fixes:

- native-windows has no <sys/statvfs.h>, so the Portduino branch of
  fsTotalBytes()/fsUsedBytes() broke the Windows build. Switch to
  std::filesystem::space(), which is already used under ARCH_PORTDUINO in
  HostMetrics.cpp and works on both POSIX and MinGW. Errors report "full"
  so the capacity check still fails safe.

- This PR adds test/test_event_profile_storage, taking test/ from 40 to 41
  suite directories, which trips the native-suite-count reconciliation check.

* fix(event): scope boot-write deferral to the radio profile, address review

Review feedback:

- Copilot: saveProto()'s boot-write deferral applied to every file, so
  loadFromDisk()'s recovery writes (e.g. restoring owner fields into
  devicestate) were silently dropped and never retried, because the ctor CRC
  baselines are computed after loadFromDisk(). Deferral now applies only to
  the radio-profile files, via isRadioProfileFile().

- jp-bennett: eventConfigFromStandard() wrapped a struct copy plus one field
  assignment in a header helper with its own unit test. Inlined at its single
  call site and removed; the behaviour is covered end-to-end by hardware
  validation instead (RAK4631 normal -> event -> normal preserves NodeNum and
  public key while swapping LoRa, and restores the original channel
  byte-identically).

- jp-bennett: the active-backup encrypted-storage migration ran for normal
  builds too, which changed non-event behaviour and contradicted the PR's
  stated event-only scope. Scoped to USERPREFS_EVENT_MODE; the adjacent block
  already covers the inactive standard backup in event builds.

New tests (all verified to fail under mutation, not vacuous):

- test_event_paths_never_collide_with_standard_or_shared_files: the core
  safety property. A path-table slip would make event firmware overwrite the
  user's real config, channels or backup, or capture a shared file like
  devicestate/nodedb. Nothing asserted this before.

- test_only_radio_profile_files_defer_boot_writes: guards the deferral fix
  above so re-widening it fails loudly.

- test_event_reservation_fits_smallest_supported_filesystem: the reservation
  is compile-time but must fit filesystems as small as 14 KiB (STM32WL) and
  28 KiB (nRF52840). Protobuf growth pushing it past those would silently
  stop event profiles persisting - the exact failure mode confirmed by
  fault injection on a RAK4631.

Verified with USERPREFS_EVENT_MODE both on and off: 7/7 tests pass, and
rak4631, heltec-v3, rak11310 and rak3172 all build clean.

* fix: preserve event profile storage recovery

---------

Co-authored-by: Jonathan Bennett <jbennett@incomsystems.biz>
Co-authored-by: Ben Meadors <benmmeadors@gmail.com>
Co-authored-by: Benjamin Faershtein <benjaminfaershtein@Benjamins-MacBook-Pro-2.local>

src/FSCommon.cpp

@@ -12,6 +12,85 @@
 #include "SPILock.h"
 #include "configuration.h"
 
+#if defined(ARCH_PORTDUINO)
+#include <filesystem>
+#endif
+
+#if defined(ARCH_NRF52) || defined(ARCH_STM32)
+// Adafruit_LittleFS (nRF52) and STM32_LittleFS both wrap littlefs v1, which predates lfs_fs_size().
+// Count the blocks currently in use with lfs_traverse() instead.
+static int fsCountBlockCb(void *ctx, lfs_block_t)
+{
+    *static_cast<size_t *>(ctx) += 1;
+    return 0;
+}
+
+size_t fsTotalBytes()
+{
+    lfs_t *fs = FSCom._getFS();
+    if (!fs || !fs->cfg)
+        return 0;
+    return (size_t)fs->cfg->block_count * (size_t)fs->cfg->block_size;
+}
+
+size_t fsUsedBytes()
+{
+    lfs_t *fs = FSCom._getFS();
+    if (!fs || !fs->cfg)
+        return 0;
+    size_t blocks = 0;
+    FSCom._lockFS();
+    int err = lfs_traverse(fs, fsCountBlockCb, &blocks);
+    FSCom._unlockFS();
+    if (err < 0)
+        return fsTotalBytes(); // report "full" so capacity checks fail safe
+    return blocks * (size_t)fs->cfg->block_size;
+}
+#elif defined(ARCH_RP2040)
+// arduino-pico reports capacity through FSInfo rather than as methods.
+size_t fsTotalBytes()
+{
+    FSInfo info;
+    return FSCom.info(info) ? (size_t)info.totalBytes : 0;
+}
+
+size_t fsUsedBytes()
+{
+    FSInfo info;
+    return FSCom.info(info) ? (size_t)info.usedBytes : 0;
+}
+#elif defined(ARCH_PORTDUINO)
+// Portduino is backed by the host filesystem; ask the OS about the volume holding the working
+// directory. std::filesystem keeps this working on native-windows too, where statvfs() does not
+// exist. On error we report "full" so capacity checks fail safe.
+size_t fsTotalBytes()
+{
+    std::error_code ec;
+    const auto info = std::filesystem::space(".", ec);
+    return ec ? 0 : (size_t)info.capacity;
+}
+
+size_t fsUsedBytes()
+{
+    std::error_code ec;
+    const auto info = std::filesystem::space(".", ec);
+    if (ec || info.capacity < info.available)
+        return fsTotalBytes();
+    return (size_t)(info.capacity - info.available);
+}
+#else
+// ESP32 LittleFS and the nRF54L15 wrapper expose these directly.
+size_t fsTotalBytes()
+{
+    return FSCom.totalBytes();
+}
+
+size_t fsUsedBytes()
+{
+    return FSCom.usedBytes();
+}
+#endif
+
 // Software SPI is used by MUI so disable SD card here until it's also implemented
 #if defined(HAS_SDCARD) && !defined(SDCARD_USE_SOFT_SPI)
 #include <SD.h>

src/FSCommon.h

@@ -56,6 +56,12 @@ using namespace Adafruit_LittleFS_Namespace;
 using namespace Adafruit_LittleFS_Namespace;
 #endif
 
+// Filesystem capacity, in bytes. Only ESP32's LittleFS and the nRF54L15 wrapper expose totalBytes()/usedBytes()
+// directly; the other backends need per-platform work (littlefs v1 traversal, FSInfo, statvfs), so callers must
+// use these helpers rather than reaching into FSCom.
+size_t fsTotalBytes();
+size_t fsUsedBytes();
+
 void fsInit();
 bool renameFile(const char *pathFrom, const char *pathTo);
 bool fsFormat();

src/mesh/NodeDB.cpp

@@ -638,6 +638,7 @@ NodeDB::NodeDB()
 #endif
     sortMeshDB();
     saveToDisk(saveWhat);
+    bootInitializationInProgress = false;
 }
 
 /**
@@ -2193,6 +2194,41 @@ void NodeDB::loadFromDisk()
 
     migrationSavePending = false;
     configDecodeFailed = false;
+    configLoadComplete = false;
+
+#if !USERPREFS_EVENT_MODE
+#ifdef FSCom
+    const char *eventProfileFiles[] = {EVENT_CONFIG_FILE_NAME, EVENT_CHANNEL_FILE_NAME, EVENT_BACKUP_FILE_NAME};
+    spiLock->lock();
+    for (const char *filename : eventProfileFiles) {
+        if (FSCom.exists(filename) && !FSCom.remove(filename))
+            LOG_WARN("Unable to remove stale event profile file %s", filename);
+    }
+    spiLock->unlock();
+#endif
+#endif
+
+#if USERPREFS_EVENT_MODE
+    // Seed only a missing event config; never overwrite normal files after a corrupt event config.
+    bool eventConfigMissing = false;
+    eventProfileStorageUnavailable = false;
+#ifdef FSCom
+    spiLock->lock();
+    eventConfigMissing = !FSCom.exists(configFileName);
+    if (eventConfigMissing) {
+        const size_t totalBytes = fsTotalBytes();
+        const size_t usedBytes = fsUsedBytes();
+        eventProfileStorageUnavailable = !hasEventProfileStorageSpace(totalBytes, usedBytes);
+        if (eventProfileStorageUnavailable) {
+            LOG_ERROR("Event profile requires %u bytes free; only %u bytes available. Profile changes will not persist.",
+                      static_cast<unsigned>(EVENT_PROFILE_STORAGE_RESERVATION_BYTES),
+                      static_cast<unsigned>(totalBytes >= usedBytes ? totalBytes - usedBytes : 0));
+        }
+    }
+    spiLock->unlock();
+#endif
+    bool initializedEventConfig = false;
+#endif
 
     meshtastic_Config_SecurityConfig backupSecurity = meshtastic_Config_SecurityConfig_init_zero;
 
@@ -2382,6 +2418,31 @@ void NodeDB::loadFromDisk()
 
     state = loadProto(configFileName, meshtastic_LocalConfig_size, sizeof(meshtastic_LocalConfig), &meshtastic_LocalConfig_msg,
                       &config);
+#if USERPREFS_EVENT_MODE
+    if (eventConfigMissing && state != LoadFileResult::LOAD_SUCCESS) {
+        const LoadFileResult eventConfigState = state;
+        const LoadFileResult standardConfigState =
+            loadProto(STANDARD_CONFIG_FILE_NAME, meshtastic_LocalConfig_size, sizeof(meshtastic_LocalConfig),
+                      &meshtastic_LocalConfig_msg, &config);
+        if (standardConfigState == LoadFileResult::LOAD_SUCCESS) {
+            // Preserve the user's identity and non-radio preferences, then
+            // replace only LoRa with this event build's compiled defaults.
+            const meshtastic_LocalConfig standardConfig = config;
+            installDefaultConfig(true);
+            const meshtastic_Config_LoRaConfig eventLora = config.lora;
+            config = standardConfig;
+            config.has_lora = true;
+            config.lora = eventLora;
+            state = LoadFileResult::LOAD_SUCCESS;
+            initializedEventConfig = true;
+            LOG_INFO("Initialized event config without modifying %s", STANDARD_CONFIG_FILE_NAME);
+        } else {
+            // Keep the event load outcome because loadProto() clears config before decoding.
+            // A normal decode failure must not create a replacement identity.
+            state = standardConfigState == LoadFileResult::DECODE_FAILED ? LoadFileResult::DECODE_FAILED : eventConfigState;
+        }
+    }
+#endif
     if (state == LoadFileResult::DECODE_FAILED) {
         // Config file present but undecodable this boot (corruption / torn write / transient decrypt fail).
         // loadProto() already zeroed `config`, so the keypair is gone from RAM; minting a new one would change
@@ -2403,6 +2464,7 @@ void NodeDB::loadFromDisk()
     } else {
         LOG_INFO("Loaded saved config version %d", config.version);
     }
+    configLoadComplete = true;
 
     // Coerce LoRa config fields derived from presets while bootstrapping.
     // Some clients/UI components display bandwidth/spread_factor directly from config even in preset mode.
@@ -2443,6 +2505,15 @@ void NodeDB::loadFromDisk()
     config.lora.override_frequency = USERPREFS_LORACONFIG_OVERRIDE_FREQUENCY;
 #endif
 
+#if USERPREFS_EVENT_MODE
+    if (initializedEventConfig) {
+        // This is the first durable event-profile write.  A failed write is
+        // safe: normal files remain untouched and the next event boot retries.
+        if (!saveToDisk(SEGMENT_CONFIG))
+            LOG_ERROR("Unable to persist initial event config");
+    }
+#endif
+
     if (backupSecurity.private_key.size > 0) {
         LOG_DEBUG("Restoring backup of security config");
         config.security = backupSecurity;
@@ -2557,7 +2628,7 @@ void NodeDB::loadFromDisk()
         const int segments[] = {SEGMENT_CONFIG, SEGMENT_MODULECONFIG, SEGMENT_CHANNELS, SEGMENT_DEVICESTATE,
                                 SEGMENT_NODEDATABASE};
         int toSave = 0;
-        for (int i = 0; i < 5; i++) {
+        for (size_t i = 0; i < sizeof(segments) / sizeof(segments[0]); i++) {
             if (!EncryptedStorage::isEncrypted(filesToCheck[i])) {
                 toSave |= segments[i];
             }
@@ -2574,6 +2645,43 @@ void NodeDB::loadFromDisk()
                 EncryptedStorage::migrateFile(fn);
             }
         }
+
+        // Backups are outside saveToDisk(), but can contain radio profile PSKs. Only event builds
+        // introduce a second backup file, so leave normal-firmware backup handling unchanged.
+#if USERPREFS_EVENT_MODE
+#ifdef FSCom
+        spiLock->lock();
+        const bool activeBackupExists = FSCom.exists(backupFileName);
+        spiLock->unlock();
+        if (activeBackupExists && !EncryptedStorage::isEncrypted(backupFileName)) {
+            LOG_INFO("Migrating %s to encrypted storage", backupFileName);
+            if (!EncryptedStorage::migrateFile(backupFileName)) {
+                LOG_ERROR("Unable to migrate %s to encrypted storage", backupFileName);
+                storageCorruptThisLoad = true;
+            }
+        }
+#endif
+#endif
+
+        // Event firmware keeps the normal radio profile inactive, so migrate it separately.
+#if USERPREFS_EVENT_MODE
+#ifdef FSCom
+        const char *inactiveRadioProfileFiles[] = {STANDARD_CONFIG_FILE_NAME, STANDARD_CHANNEL_FILE_NAME,
+                                                   STANDARD_BACKUP_FILE_NAME};
+        for (const char *fn : inactiveRadioProfileFiles) {
+            spiLock->lock();
+            const bool exists = FSCom.exists(fn);
+            spiLock->unlock();
+            if (exists && !EncryptedStorage::isEncrypted(fn)) {
+                LOG_INFO("Migrating inactive radio profile %s to encrypted storage", fn);
+                if (!EncryptedStorage::migrateFile(fn)) {
+                    LOG_ERROR("Unable to migrate %s to encrypted storage", fn);
+                    storageCorruptThisLoad = true;
+                }
+            }
+        }
+#endif
+#endif
     }
 #endif
 
@@ -2708,8 +2816,9 @@ bool NodeDB::disableLockdownToPlaintext()
     // plaintext->encrypted migrate loop above. Order does not matter here;
     // EncryptedStorage::removeLockdownArtifacts() (which deletes the DEK,
     // the commit point) only runs after every file is confirmed plaintext.
-    const char *filesToCheck[] = {configFileName, moduleConfigFileName, channelFileName, deviceStateFileName,
-                                  nodeDatabaseFileName};
+    const char *filesToCheck[] = {STANDARD_CONFIG_FILE_NAME, STANDARD_CHANNEL_FILE_NAME, STANDARD_BACKUP_FILE_NAME,
+                                  EVENT_CONFIG_FILE_NAME,    EVENT_CHANNEL_FILE_NAME,    EVENT_BACKUP_FILE_NAME,
+                                  moduleConfigFileName,      deviceStateFileName,        nodeDatabaseFileName};
     for (const char *fn : filesToCheck) {
         if (!EncryptedStorage::migrateFileToPlaintext(fn)) {
             LOG_ERROR("NodeDB: failed to revert %s to plaintext; aborting disable (device stays in lockdown)", fn);
@@ -2729,6 +2838,15 @@ bool NodeDB::saveProto(const char *filename, size_t protoSize, const pb_msgdesc_
                        bool fullAtomic)
 {
 
+    // Only the radio profile is at risk from an unverified config load, so only defer those writes.
+    // Devicestate/nodedb/module writes must still land, otherwise boot-time recovery (e.g. loadFromDisk()
+    // restoring owner fields) is dropped and never retried.
+    if (isRadioProfileFile(filename) &&
+        shouldDeferBootPersistence(bootInitializationInProgress, configLoadComplete, configDecodeFailed)) {
+        LOG_WARN("NodeDB: deferred boot write to %s until config recovery completes", filename);
+        return true;
+    }
+
     // do not try to save anything if power level is not safe. In many cases flash will be lock-protected
     // and all writes will fail anyway. Device should be sleeping at this point anyway.
     if (!powerHAL_isPowerLevelSafe()) {
@@ -2981,6 +3099,19 @@ bool NodeDB::saveToDiskNoRetry(int saveWhat)
     spiLock->unlock();
 #endif
 
+#if USERPREFS_EVENT_MODE
+    if (eventProfileStorageUnavailable) {
+        if (saveWhat & SEGMENT_CONFIG) {
+            LOG_WARN("Skipping event config write: insufficient profile storage at boot");
+            saveWhat &= ~SEGMENT_CONFIG;
+        }
+        if (saveWhat & SEGMENT_CHANNELS) {
+            LOG_WARN("Skipping event channel write: insufficient profile storage at boot");
+            saveWhat &= ~SEGMENT_CHANNELS;
+        }
+    }
+#endif
+
     if (saveWhat & SEGMENT_CONFIG) {
         config.has_device = true;
         config.has_display = true;

src/mesh/NodeDB.h

@@ -112,11 +112,57 @@ extern meshtastic_Position localPosition;
 static constexpr const char *deviceStateFileName = "/prefs/device.proto";
 static constexpr const char *legacyPrefFileName = "/prefs/db.proto";
 static constexpr const char *nodeDatabaseFileName = "/prefs/nodes.proto";
-static constexpr const char *configFileName = "/prefs/config.proto";
+// Event builds isolate radio profiles so normal firmware resumes its config and channels after OTA.
+static constexpr const char *STANDARD_CONFIG_FILE_NAME = "/prefs/config.proto";
+static constexpr const char *STANDARD_CHANNEL_FILE_NAME = "/prefs/channels.proto";
+static constexpr const char *EVENT_CONFIG_FILE_NAME = "/prefs/event-config.proto";
+static constexpr const char *EVENT_CHANNEL_FILE_NAME = "/prefs/event-channels.proto";
+static constexpr const char *STANDARD_BACKUP_FILE_NAME = "/backups/backup.proto";
+static constexpr const char *EVENT_BACKUP_FILE_NAME = "/backups/event-backup.proto";
+
+struct RadioProfileStoragePaths {
+    const char *config;
+    const char *channels;
+    const char *backup;
+};
+
+constexpr RadioProfileStoragePaths radioProfileStoragePaths(bool eventMode)
+{
+    return eventMode ? RadioProfileStoragePaths{EVENT_CONFIG_FILE_NAME, EVENT_CHANNEL_FILE_NAME, EVENT_BACKUP_FILE_NAME}
+                     : RadioProfileStoragePaths{STANDARD_CONFIG_FILE_NAME, STANDARD_CHANNEL_FILE_NAME, STANDARD_BACKUP_FILE_NAME};
+}
+
+// Reserve event files and their atomic temporaries before seeding, preventing retry formatting on full storage.
+static constexpr size_t EVENT_PROFILE_STORAGE_RESERVATION_BYTES = 2 * (meshtastic_LocalConfig_size + meshtastic_ChannelFile_size);
+
+constexpr bool hasEventProfileStorageSpace(size_t totalBytes, size_t usedBytes)
+{
+    return usedBytes <= totalBytes && totalBytes - usedBytes >= EVENT_PROFILE_STORAGE_RESERVATION_BYTES;
+}
+
+constexpr bool shouldDeferBootPersistence(bool bootInitializationInProgress, bool configLoadComplete, bool configDecodeFailed)
+{
+    return bootInitializationInProgress && (!configLoadComplete || configDecodeFailed);
+}
+
+#if USERPREFS_EVENT_MODE
+static constexpr auto RADIO_PROFILE_STORAGE = radioProfileStoragePaths(true);
+#else
+static constexpr auto RADIO_PROFILE_STORAGE = radioProfileStoragePaths(false);
+#endif
+static constexpr const char *configFileName = RADIO_PROFILE_STORAGE.config;
+static constexpr const char *channelFileName = RADIO_PROFILE_STORAGE.channels;
+static constexpr const char *backupFileName = RADIO_PROFILE_STORAGE.backup;
 static constexpr const char *uiconfigFileName = "/prefs/uiconfig.proto";
 static constexpr const char *moduleConfigFileName = "/prefs/module.proto";
-static constexpr const char *channelFileName = "/prefs/channels.proto";
-static constexpr const char *backupFileName = "/backups/backup.proto";
+
+// An unverified config load only endangers the radio profile, so only these files take part in
+// boot-write deferral. Lives next to the path table above so the two cannot drift apart.
+inline bool isRadioProfileFile(const char *filename)
+{
+    return strcmp(filename, configFileName) == 0 || strcmp(filename, channelFileName) == 0 ||
+           strcmp(filename, backupFileName) == 0;
+}
 
 /// Given a node, return how many seconds in the past (vs now) that we last heard from it
 uint32_t sinceLastSeen(const meshtastic_NodeInfoLite *n);
@@ -560,6 +606,14 @@ class NodeDB
     /// skip boot keygen and skip persisting defaults, so a transient read failure can't change our NodeNum
     /// or overwrite the on-disk config. Cleared at the top of every loadFromDisk() run.
     bool configDecodeFailed = false;
+    // Defer automatic writes until config load is healthy to protect device and node data from damaged configs.
+    bool bootInitializationInProgress = true;
+    bool configLoadComplete = false;
+#if USERPREFS_EVENT_MODE
+    // The active event profile is intentionally non-durable when there was not
+    // enough room to create it safely at boot. A later boot retries the check.
+    bool eventProfileStorageUnavailable = false;
+#endif
     uint32_t lastNodeDbSave = 0;     // when we last saved our db to flash
     uint32_t lastFullEvictionMs = 0; // when we last evicted to admit a new node, once the db is full
     uint32_t lastBackupAttempt = 0;  // when we last tried a backup automatically or manually

test/native-suite-count

@@ -1 +1 @@
-40
+41

test/test_event_profile_storage/test_main.cpp

@@ -0,0 +1,124 @@
+#include "MeshTypes.h" // Include BEFORE TestUtil.h
+#include "TestUtil.h"
+#include "mesh/NodeDB.h"
+#include <unity.h>
+
+void test_standard_profile_uses_standard_files()
+{
+    const auto paths = radioProfileStoragePaths(false);
+
+    TEST_ASSERT_EQUAL_STRING("/prefs/config.proto", paths.config);
+    TEST_ASSERT_EQUAL_STRING("/prefs/channels.proto", paths.channels);
+    TEST_ASSERT_EQUAL_STRING("/backups/backup.proto", paths.backup);
+}
+
+void test_event_profile_uses_isolated_files()
+{
+    const auto paths = radioProfileStoragePaths(true);
+
+    TEST_ASSERT_EQUAL_STRING("/prefs/event-config.proto", paths.config);
+    TEST_ASSERT_EQUAL_STRING("/prefs/event-channels.proto", paths.channels);
+    TEST_ASSERT_EQUAL_STRING("/backups/event-backup.proto", paths.backup);
+}
+
+void test_boot_defers_persistence_until_config_is_verified()
+{
+    TEST_ASSERT_TRUE(shouldDeferBootPersistence(true, false, false));
+    TEST_ASSERT_TRUE(shouldDeferBootPersistence(true, true, true));
+    TEST_ASSERT_FALSE(shouldDeferBootPersistence(true, true, false));
+    TEST_ASSERT_FALSE(shouldDeferBootPersistence(false, true, true));
+}
+
+void test_event_profile_requires_room_for_atomic_profile_writes()
+{
+    TEST_ASSERT_TRUE(hasEventProfileStorageSpace(EVENT_PROFILE_STORAGE_RESERVATION_BYTES, 0));
+    TEST_ASSERT_FALSE(hasEventProfileStorageSpace(EVENT_PROFILE_STORAGE_RESERVATION_BYTES - 1, 0));
+    TEST_ASSERT_FALSE(hasEventProfileStorageSpace(EVENT_PROFILE_STORAGE_RESERVATION_BYTES, 1));
+    TEST_ASSERT_FALSE(hasEventProfileStorageSpace(1, 2));
+    // A full filesystem must never look like it has room.
+    TEST_ASSERT_FALSE(
+        hasEventProfileStorageSpace(EVENT_PROFILE_STORAGE_RESERVATION_BYTES, EVENT_PROFILE_STORAGE_RESERVATION_BYTES));
+}
+
+// The whole point of the feature is that an event build never touches the user's real radio profile
+// or the shared files. A copy/paste slip in the path table would silently overwrite them, which no
+// amount of runtime testing would catch on a device that had never held a normal profile.
+void test_event_paths_never_collide_with_standard_or_shared_files()
+{
+    const auto standard = radioProfileStoragePaths(false);
+    const auto event = radioProfileStoragePaths(true);
+
+    TEST_ASSERT_NOT_EQUAL(0, strcmp(event.config, standard.config));
+    TEST_ASSERT_NOT_EQUAL(0, strcmp(event.channels, standard.channels));
+    TEST_ASSERT_NOT_EQUAL(0, strcmp(event.backup, standard.backup));
+
+    // The three event paths must also be distinct from each other.
+    TEST_ASSERT_NOT_EQUAL(0, strcmp(event.config, event.channels));
+    TEST_ASSERT_NOT_EQUAL(0, strcmp(event.config, event.backup));
+    TEST_ASSERT_NOT_EQUAL(0, strcmp(event.channels, event.backup));
+
+    // Files shared by both profiles must never be captured by either profile's paths.
+    const char *sharedFiles[] = {deviceStateFileName, nodeDatabaseFileName, moduleConfigFileName, uiconfigFileName,
+                                 legacyPrefFileName};
+    for (const char *shared : sharedFiles) {
+        TEST_ASSERT_NOT_EQUAL(0, strcmp(event.config, shared));
+        TEST_ASSERT_NOT_EQUAL(0, strcmp(event.channels, shared));
+        TEST_ASSERT_NOT_EQUAL(0, strcmp(event.backup, shared));
+        TEST_ASSERT_NOT_EQUAL(0, strcmp(standard.config, shared));
+        TEST_ASSERT_NOT_EQUAL(0, strcmp(standard.channels, shared));
+        TEST_ASSERT_NOT_EQUAL(0, strcmp(standard.backup, shared));
+    }
+}
+
+// Boot-write deferral must cover the radio profile and nothing else: widening it silently drops
+// boot-time recovery writes (devicestate/nodedb) that are never retried.
+void test_only_radio_profile_files_defer_boot_writes()
+{
+    TEST_ASSERT_TRUE(isRadioProfileFile(configFileName));
+    TEST_ASSERT_TRUE(isRadioProfileFile(channelFileName));
+    TEST_ASSERT_TRUE(isRadioProfileFile(backupFileName));
+
+    TEST_ASSERT_FALSE(isRadioProfileFile(deviceStateFileName));
+    TEST_ASSERT_FALSE(isRadioProfileFile(nodeDatabaseFileName));
+    TEST_ASSERT_FALSE(isRadioProfileFile(moduleConfigFileName));
+    TEST_ASSERT_FALSE(isRadioProfileFile(uiconfigFileName));
+}
+
+// The reservation is compile-time, but the filesystems it has to fit in are tiny: nRF52840
+// InternalFS is 28 KiB and the STM32WL family is 14 KiB. If protobuf growth pushes the reservation
+// past what those can spare, event builds silently stop persisting their profile.
+void test_event_reservation_fits_smallest_supported_filesystem()
+{
+    constexpr size_t STM32WL_FILESYSTEM_BYTES = 14 * 1024;
+    constexpr size_t NRF52840_FILESYSTEM_BYTES = 28 * 1024;
+
+    TEST_ASSERT_EQUAL_UINT32(2 * (meshtastic_LocalConfig_size + meshtastic_ChannelFile_size),
+                             EVENT_PROFILE_STORAGE_RESERVATION_BYTES);
+
+    // Leave at least half of the smallest filesystem for everything else under /prefs.
+    TEST_ASSERT_LESS_THAN_UINT32(STM32WL_FILESYSTEM_BYTES / 2, EVENT_PROFILE_STORAGE_RESERVATION_BYTES);
+    TEST_ASSERT_TRUE(hasEventProfileStorageSpace(NRF52840_FILESYSTEM_BYTES, 0));
+    TEST_ASSERT_TRUE(hasEventProfileStorageSpace(STM32WL_FILESYSTEM_BYTES, 0));
+}
+
+void setUp(void) {}
+
+void tearDown(void) {}
+
+extern "C" {
+void setup()
+{
+    initializeTestEnvironment();
+    UNITY_BEGIN();
+    RUN_TEST(test_standard_profile_uses_standard_files);
+    RUN_TEST(test_event_profile_uses_isolated_files);
+    RUN_TEST(test_boot_defers_persistence_until_config_is_verified);
+    RUN_TEST(test_event_profile_requires_room_for_atomic_profile_writes);
+    RUN_TEST(test_event_paths_never_collide_with_standard_or_shared_files);
+    RUN_TEST(test_only_radio_profile_files_defer_boot_writes);
+    RUN_TEST(test_event_reservation_fits_smallest_supported_filesystem);
+    exit(UNITY_END());
+}
+
+void loop() {}
+}