Keep the image small enough for cubes on the old partition table

[elliotmatson]

Problem

A cube still on v0.6.0-b1 downloads v0.6.1 to 99% and then fails, through both the GitHub updater and the dashboard upload card (ESP_ERR_INVALID_… on the card).

It has Arduino's old min_spiffs.csv partition table, whose app slots are 0x1E0000 = 1,966,080 bytes. Partition tables only change over USB, so it kept that layout through every OTA update. b1 (1,908,496 bytes) fits; telemetry and lost mode took v0.6.0/v0.6.1 to 1,983,728 bytes, 17 KB over. 1,966,080 / 1,983,728 = 99.1%.

Reproduced here by flashing that partition table and b1 to a cube:

E Updates: OTA write failed: ESP_ERR_INVALID_SIZE
E Updates: GitHub update failed (1966080 of 1983728 bytes): ESP_ERR_INVALID_SIZE

Fix

• CONFIG_COMPILER_OPTIMIZATION_ASSERTIONS_SILENT: assertions still stop the cube, but no longer compile in each one's file name and expression. About 59 KB smaller, no speed cost. (-Os would save more but slows rendering.)
• scripts/size_guard.py: fails the build if firmware.bin outgrows the old 0x1E0000 slot again.
• CLAUDE.md note.

Local build: 1,915,936 bytes, 50 KB under the old slot.

🤖 Generated with Claude Code

[github-actions]

Tests

124/124 passed.

Suite	Tests	Passed	Failed	Time
native:test_firmware_image	14	14	0	3.17s
native:test_pong	6	6	0	0.71s
native:test_remote	7	7	0	0.73s
native:test_rubiks	7	7	0	0.54s
native:test_timezones	5	5	0	0.59s
native:test_sand	6	6	0	0.54s
native:test_bounce	6	6	0	0.64s
native:test_maze	4	4	0	0.56s
native:test_cube_geometry	22	22	0	0.69s
native:test_life	7	7	0	0.58s
native:test_noise	5	5	0	0.67s
native:test_breakout	6	6	0	0.59s
native:test_wordclock	5	5	0	0.57s
native:test_color	6	6	0	0.57s
native:test_langton	5	5	0	0.55s
native:test_particles	7	7	0	0.58s
native:test_weather	6	6	0	0.65s

[github-actions]

Static analysis

No defects found.

_{pio check, failing on high and above. 1 defect in downloaded dependencies withheld; pass include-dependencies to see them.}

[github-actions]

Firmware size

+28.4 KB across 1 environment.

Env	Image	Δ	App partition	Flash Δ	RAM Δ
esp32-s3-devkitc-1 ⚠️	1.84 MB	+28.4 KB	23.7% → 24.07%	+28.4 KB	+34.3 KB

esp32-s3-devkitc-1 — 8 section(s) changed

Section	Base	Head	Δ
.flash_rodata_dummy	1.19 MB	1.25 MB	+64.0 KB
.flash.text	1.18 MB	1.23 MB	+58.2 KB
.flash.rodata	517.6 KB	496.4 KB	-21.3 KB
.dram0.dummy	87.5 KB	82.8 KB	-4.8 KB
.iram0.text	102.4 KB	97.7 KB	-4.7 KB
.dram0.data	23.8 KB	20.0 KB	-3.9 KB
.dram0.bss	37.8 KB	37.9 KB	+184 B
.iram0.text_end	61 B	37 B	-24 B

esp32-s3-devkitc-1 — 1136 symbol(s) changed

Symbol	Base	Head	Δ
esp_mqtt_task	0 B	4.5 KB	+4.5 KB
Telemetry::publishBoot()	0 B	2.8 KB	+2.8 KB
Telemetry::publishCrash(bool)	0 B	2.8 KB	+2.8 KB
Telemetry::scanInto(ArduinoJson::V743PB22::JsonArray, int)	0 B	2.1 KB	+2.1 KB
esp_mqtt_set_config	0 B	2.0 KB	+2.0 KB
_ZNK11ArduinoJson8V743PB226detail11VariantData6acceptINS1_14JsonSerializerINS1_6WriterI6StringvEEEEEENT_11result_typeERS9_PKNS1_15ResourceManagerE$isra$0	1.5 KB	3.4 KB	+2.0 KB
Telemetry::publishSettings()	0 B	1.9 KB	+1.9 KB
__func__$0	2.0 KB	256 B	-1.8 KB
ws_read	0 B	1.5 KB	+1.5 KB
Telemetry::publishLocation()	0 B	1.5 KB	+1.5 KB
__func__$1	1.6 KB	161 B	-1.4 KB
packet$5	0 B	1.4 KB	+1.4 KB
packet$6	1.4 KB	0 B	-1.4 KB
tcp_connect	638 B	2.0 KB	+1.4 KB
Telemetry::publishHealth()	0 B	1.4 KB	+1.4 KB
+1121 more

_{Baseline: ec0c25b. Image size is firmware.bin against the smaller app partition slot. RAM is static allocation only — the linker cannot see heap or stack.}