diff --git a/dashboard/js/onboard.js b/dashboard/js/onboard.js
index e4a4194..4822cc7 100644
--- a/dashboard/js/onboard.js
+++ b/dashboard/js/onboard.js
@@ -533,7 +533,7 @@
 
                 await loader.writeFlash({
                     fileArray: [{ data: firmwareData, address: offset }],
-                    flashSize: 'detect',
+                    flashSize: '4MB',
                     flashMode: 'dio',
                     flashFreq: '80m',
                     eraseAll: false,
diff --git a/firmware/partitions.csv b/firmware/partitions.csv
index 793daf4..f367c4e 100644
--- a/firmware/partitions.csv
+++ b/firmware/partitions.csv
@@ -1,11 +1,10 @@
 # Name,   Type, SubType, Offset,  Size, Flags
 # NVS, PHY init, and OTA data in standard low-flash locations
 nvs,      data, nvs,     0x9000,  0x6000,
-phy_init, data, phy,     0xf000,  0x1000,
-# Factory app at standard 0x10000 offset (4 MB)
-factory,  app,  factory, 0x10000, 0x400000,
-# Dual OTA partitions for A/B updates with rollback
-ota_0,    app,  ota_0,   0x410000,0x400000,
-ota_1,    app,  ota_1,   0x810000,0x400000,
+phy_init, data, phy,     0xF000,  0x1000,
+# Factory app at standard 0x10000 offset (~1.9MB — fits current ~1.7MB binary)
+factory,  app,  factory, 0x10000, 0x1F0000,
+# Single OTA partition for A/B updates with rollback (fits in 4MB flash)
+ota_0,    app,  ota_0,   0x200000,0x1F0000,
 # OTA data partition — bootloader uses this to track which OTA slot to boot
-otadata,  data, ota,     0xc10000,0x2000,
+otadata,  data, ota,     0x3F0000,0x2000,
diff --git a/firmware/sdkconfig.defaults b/firmware/sdkconfig.defaults
index 9868a07..58a84b0 100644
--- a/firmware/sdkconfig.defaults
+++ b/firmware/sdkconfig.defaults
@@ -4,9 +4,11 @@
 # Chip target
 CONFIG_IDF_TARGET="esp32s3"
 
-# Flash size — partitions.csv requires 12.1MB (factory 4MB + ota_0 4MB + ota_1 4MB)
-CONFIG_ESPTOOLPY_FLASHSIZE_16MB=y
-CONFIG_ESPTOOLPY_FLASHSIZE="16MB"
+# Flash size — partitions.csv requires ~3.9MB (factory 1.9MB + ota_0 1.9MB + otadata)
+# Using 4MB as minimum supported flash. Safe on 16MB boards: spi_flash only panics
+# when physical < header, not when physical > header.
+CONFIG_ESPTOOLPY_FLASHSIZE_4MB=y
+CONFIG_ESPTOOLPY_FLASHSIZE="4MB"
 
 # WiFi CSI Configuration
 CONFIG_ESP_WIFI_RX_BCN_ADAPT=y