G3 repeater PSRAM storage, 2026-10-27

The G3 Full repeater frees 36,776 bytes of static internal RAM by moving its channel/scope tables and advert-limit history to PSRAM. The MQTT SDK WebSocket buffers also prefer PSRAM: 2,050 bytes per initialized client, or 10,250 bytes with five initialized clients. Capacities, saved formats and radio queues remain unchanged.

These are linked measurements and verified allocation sizes. No G3 was flashed; running heap, RF timing and sustained broker load were not measured. The machine-readable evidence records the matched builds, hashes and checks.

Matched builds

Baseline: 88bfaebb5. Final: the production changes accompanying this report. Both use the same G3 Full recipe, version, Cascade profile and USA preset.

Measurement	Baseline	Final
Internal BSS bytes	142,088	105,312
Internal data bytes	23,980	23,980
Linked internal heap capacity	199,976	236,752
Modeled internal requirement	197,808	234,636
Conservative admission margin	2,168	2,116
Packaged application bytes	2,156,504	2,155,752
OTA application-slot bytes	6,553,600	6,553,600

The model still reserves complete internal fallback for both tables: 18,892 bytes for scope storage and 17,936 for advert history, including overhead. That explains why the conservative admission margin does not rise with the normal PSRAM-backed free heap. The 16 KiB DMA reserve and existing startup requirements are unchanged. All 16 capability checks pass, with no declared feature reductions; WiFi/LoRa OTA, MQTT, logging, WebConfig, bridges and host KISS remain compiled in.

Allocation behavior

G3 repeater defaults select PSRAM for all 255 scope entries, 32 direct-scope names, 255 scope requirements and 128 advert-source histories.
Allocation happens once during construction. Array references preserve addresses, complete-array sizeof, file formats and rollback behavior.
The pinned ESP32-S3 SDK initializes PSRAM heaps before global constructors; Arduino's later psramFound() flag is not used as a constructor-time gate.
Complete internal fallback is allowed only while preserving the existing DMA reserve. Otherwise startup reports the allocation failure and stops. It never silently reduces filter or advert-protection capacity.
MESH_REPEATER_PSRAM_TABLES=0 restores inline storage. Other boards retain their existing default storage, including RTC/IRAM paths.
The IDF 4 SDK initializes both WS and WSS transports for each MQTT client, even plain MQTT. Both buffers retain the existing 1,025-byte overflow fix. A failed padded allocation destroys that transport safely instead of returning its original undersized buffer. IDF 5 remains a passthrough.

Verification

Scope storage: three ASan/UBSan tests cover full capacities, identical 18,885 persisted bytes, rollback on short writes/rename failures, lifetime, guarded fallback, fatal allocation failure and platform/SDK gates.
Advert history: four ASan/UBSan tests compare all 128 entries against inline storage, including quota, duplicate, badlist and rollover behavior. Existing RTC (eight), IRAM (seven) and native limiter (33 per backend) tests pass.
WebSocket wrapper: three ASan/UBSan tests exercise 17 scenarios across G3, other PSRAM boards, internal-only boards and IDF 4/5, including the extra byte, cleanup, parent lifetime and fallback boundaries.
RAM policy: all 63 tests pass, including six new fallback regressions. Existing policy capacity, rule layout, moderation and CLI tests pass.
Canonical G3 Full package: compile, internal-RAM admission, dual-OTA fit and capability checks pass. PlatformIO ran one process at a time.

Reproduce the final build with:

bash build.sh build-firmware Station_G3_ESP32_repeater --full-exact --firmware-version v1.18.0.2-psram-test --profile cascade --radio-preset usa-cascade-fixed --require-ota

Physical acceptance remains a G3 boot, persistence, radio traffic and MQTT reconnect/load run with internal/DMA heap monitoring. The maximum five-broker TLS/WSS/outbox workload remains unqualified by these software checks.