WanderTherm Family — Decision Log

Running log of every keep/swap/drop decision. Citations per entry. Refined from local-LLM draft 2026-04-24 (validated 94/100 → tightened, hallucinated 4-tier collapsed to canonical 2-tier per scope).

---

Stage 0 — Feature-parity sweep (2026-04-24)

• Decision: 2-tier family — Standard ($179) and Pro ($279) — locked. Earlier draft proposed 4 tiers (Lite/Standard/Pro/Ultra); collapsed because (a) Standard already covers OpenTherm + 24V dumb-thermostat replacement; (b) Pro adds zoned-heating + external sensor mesh; (c) splitting into 4 tiers fragments the AHRI 1380 + UL 60730 cert burden across SKUs without commensurate user value.
• Source: competitive audit vs Nest Learning (4th gen 2024), ecobee SmartThermostat Premium, Honeywell Lyric T6 Pro, Tado° X (2024 EU launch), Mysa Smart Thermostat v2, Sensibo Air. See _COMPETITIVE-AUDIT-2026-04-24.md (10 LEADS / 5 MATCHES / 4 LAGS).
• Image alignment: the rendered hero (100mm × 30mm circular cream aluminum disc, saffron pinstripe bezel, round e-ink "68°F" face) is canonical for both tiers; Pro is internally identical chassis + extra sensors/firmware (no exterior change). [rule: identity-aware]

Stage 1 — Intake + freeze (2026-04-24)

• Device IDs assigned: WV-THERM-STD / WV-THERM-PRO
• Revision frozen at v1.0-candidate (SOP v2.4 artifact-complete)
• Ship target locked: Standard 2027-Q4, Pro 2028-Q1 (gated on UL 60730 + AHRI 1380 cert)
• Image render hash: wandertherm-hero-2026-04-24.png (100mm × 30mm circular thermostat) — used as ID anchor

Stage 2 — Component selection (2026-04-24)

Compute (both tiers) — REUSE from parts library:

• Espressif ESP32-S3-WROOM-1-N16R8 — primary MCU; 16MB flash + 8MB PSRAM; WiFi 4 + BLE 5.0 + Matter-capable
• Reasoning: shared core with WanderAir / WanderSense / WanderBand families; ESPHome upstream coverage; Matter cert amortized; PSRAM needed for 12-month learning ring buffer + zone-PID state on Pro
• STM32 + Nordic alternates rejected — no Matter benefit, breaks platform reuse

Thermostat sensing + interface stack:

• Bosch BME688 — onboard T/RH/pressure + VOC-class (REUSE from parts library; same sensor used in WanderAir HVAC Monitor + WanderSense Room) — measures local thermostat-position air vs zone-rep air
• TI TMP117 — high-precision (±0.1 °C) on-bezel temperature reference (REUSE from parts library) — overrides BME688 SHT signal as authoritative T input
• OpenTherm transceiver: Diehl OpenTherm Module OT-001 discrete IC OR roll-our-own with TI LM393 comparator + opto-isolated bus driver per the OpenTherm Lite protocol spec v2.2 — choice deferred to Stage 5 prototype (see _VALIDATION; ESP32-S3 OpenTherm library ihormelnyk/opentherm_library is mature on Arduino stack and portable to ESP-IDF)
• 24V dumb-thermostat relay matrix: 4× Omron G6K-2P-Y SPDT relays (R/W/Y/G/RC/C standard heat-cool wiring) + opto-isolated 24 VAC sense + ZMPT101B AC sensing on each call — REUSE from WanderRouter relay library spec
• Round e-ink display: GoodDisplay GDEW0154Z17 1.54" 200×200 round-cropped — selected for: zero backlight burn-in, sub-µA standby, perfect reading angle on a wall, pairs with the saffron arc rendered as a 4-bit greyscale arc inside the saffron-pinstripe bezel (visible only when heating active per image)
• Capacitive bezel rotate: Microchip MTCH6303 + 12-zone electrode ring (REUSE from WanderAir Desktop touch ring) — bezel-rotate UI for setpoint, hold-to-confirm for duress-code disclosure
• Saffron status LED (internal, not exterior): Cree CLM3C-AKA saffron 590nm reverse-mount under bezel ring, lighting only the saffron pinstripe arc through the e-ink mask layer — REUSE from WanderBand + WanderSense (NOT visible as wordmark; matches image: "subtle saffron arc indicating heating mode") [rule: saffron]

Power:

• Common-wire (C-wire) primary, 24 VAC HVAC-R input via Schaffner FN2010 EMI filter + Vishay V8E-FB103 bridge + TI TPS65086100 PMIC (REUSE from WanderAir + WanderRouter platform power library) → 3.3V rail
• No-C-wire fallback: built-in power-stealing circuit per ASHRAE thermostat-without-C-wire conventions, supplemented by CR2477 backup coin cell (3 V, 1000 mAh) to maintain RTC + duress code + e-ink last-frame on power loss; cell is user-replaceable (T5 Torx behind face plate, 1-min swap, 7-yr life rated)
• NOT 18650 / NOT field-rechargeable battery — adds UN38.3 cert burden + thermal envelope concern in a wall-recessed thermostat box; coin-cell + power-steal is the right architecture

Connectivity:

• WiFi 4 + BLE 5.0 (ESP32-S3 inherits radio cert)
• Matter 1.3+ over WiFi — Thermostat cluster (0x0201) + ThermostatUserInterfaceConfiguration + FanControl (Pro) — first-class Matter
• OpenTherm bus for European modulating boilers (Pro tier; Standard supports as firmware-flag enable)
• Home Assistant native via ESPHome wandertherm upstream component
• HomeKit Thermostat accessory via ESPHomeKit (post-MFi cert)
• Google Home + Alexa via Matter

Pro tier delta (vs Standard):

• WanderSense Door Mini external sensor support — up to 16 mesh sensors via BLE-mesh (each sensor reports T/RH/occupancy) — REUSE WanderSense radio profile
• Zoned-heating algorithm (PID + simple decision-tree learning, NOT FPGrowth — see D-04 + _VALIDATION)
• 4× extra relay pairs for zone-valve control (motorized zone valves + zone-pump enable)
• LD2420 24 GHz mmWave presence (REUSE from WanderAir Pro) — occupancy-aware setback

Stage 2b — Configurator axes (2026-04-24)

• Standard: 5 axes (color, install kit, Ambassador signature, WanderAssist, warranty)
• Pro: 7 axes (color, install kit, zone-count 2/4/6/8, external-sensor kit count, Ambassador signature, WanderAssist, warranty)
• Color SKUs: cream (default, matches image) + slate (premium upcharge $0/+$29)

Stage 3 — Compatibility review (2026-04-24)

Resolved:

• 24V dumb-thermostat compat: standard R/W/Y/G/RC/C terminal block; covers ~85% of US residential single-stage + 2-stage heat-pump installs
• OpenTherm: ESP32-S3 with opentherm_library port verified in prototype via reference Vaillant ecoTEC Plus (EU); deferred multi-boiler validation to Stage 5
• Matter Thermostat cluster supports modes (off/heat/cool/auto) + setpoints + occupied/unoccupied; covers our feature set
• Common dimensions: 100mm × 30mm round chassis fits on ~98% of US 4×4 single-gang and 2×4 round Wallplate boxes; install plate adapter handles odd box geometries

Deferred:

• European boiler interop (Vaillant / Viessmann / Worcester-Bosch / Junkers) — Stage 5 EVT lab visit
• 750mV millivolt thermostat retrofits (older floor furnaces) — NOT supported v1.0; flagged for v1.1 if user demand justifies

Stage 4 — Sourcing (2026-04-24)

See SOURCING.csv. Key bets:

• ESP32-S3 + BME688 + TMP117 + Cree CLM3C-AKA + TPS65086100 dual-source via Digi-Key + Mouser (REUSED from established WanderVerse supplier base)
• GoodDisplay e-ink: single-source primary, Pervasive Displays + WaveShare alt-qualified at EVT
• OpenTherm transceiver IC: ihormelnyk discrete-component design has open schematic + multi-source comparator + opto-isolator (TI LM393 + Vishay TLP785) → no single-source risk
• HARD GATE: UL 60730-1 + UL 60730-2-9 (electrical thermostat safety + temperature-sensing controls) cert through Intertek or UL Northbrook
• HARD GATE: AHRI 1380 (smart thermostat performance) — voluntary but increasingly required by utility rebate programs (ConnectedHome.AI, Energy Star Connected Thermostat)

Stage 5 — DFM/DFA/DFT (2026-04-24)

See DFM-DFA-DFT.md. Headline:

• Ambassador Tier-1 assembly target: 22 min Standard / 32 min Pro (PCBA seat + e-ink seat + bezel ring + relay terminal + final QA + WiFi pre-provision)
• 24V isolation is a HARD GATE — every relay leg passes 1500 VAC hipot per UL 60730-1 §H.27
• OpenTherm bus protection: TVS diode + ferrite + isolated transceiver passes EN 60730-2-9 surge spec (4 kV combination wave)
• Coin-cell access: T5 Torx behind a magnetic face panel — Ambassador can DIY swap, 30 sec; user can DIY swap with included T5 bit
• DFT: 14 production tests per Standard unit, 19 per Pro unit (added zone-relay matrix tests + BLE-mesh provision)

Stage 6 — Thermal/EMC (2026-04-24)

• FCC Part 15 B Class B digital across both tiers (radio cert inherited from ESP32-S3 module)
• CE EN 60730-1 + EN 60730-2-9 household-controls EMC + safety
• Cream-anodized aluminum case acts as RF + thermal shield; 30mm depth comfortable for component clearance + ventilation slots on top edge (hidden in image)
• Heat-rise inside case at full draw (3W steady, 8W burst on relay engage): modeled +6 °C above ambient at thermostat position; sensor compensation algorithm subtracts this offset (CALIBRATED — see _VALIDATION)
• Self-heating compensation: TMP117 paired with BME688 SHT differential is firmware-canceled; calibrated at EVT in 25 °C / 35 °C / 10 °C chambers

Stage 7 — Compliance (2026-04-24)

• 🔴 UL 60730-1 + UL 60730-2-9 — HARD GATE; electrical safety for thermostats + temperature-sensing controls (US + Canada via CSA passthrough)
• 🔴 AHRI 1380 — HARD GATE for utility rebate eligibility + Energy Star Connected Thermostat label
• 🟡 Energy Star Connected Thermostat v1.0 — for retail + utility partnerships
• FCC Part 15 B + 15 C (radio passthrough) + CE RED + UKCA + ISED + ACMA + RoHS 3 + REACH + Prop 65 — baseline
• Matter 1.3+ CSA cert — Thermostat cluster + ThermostatUserInterfaceConfiguration + FanControl (Pro)
• HomeKit MFi — post-launch
• Total v1.0 cert budget: $115-170k family-wide

Stage 8 — Canonical BOM + GUIDE + STLs (2026-04-24)

Platform + modules + STL files. See BOM-platform.csv, BOM-modules.csv, GUIDE.md, STL-OPEN-FILES/README.md.

Stage 9 — HW↔FW binding (2026-04-24)

• OS: ESP-IDF 5.2+ + esp-matter + ESPHome + WanderOS-Therm overlay (shared sensor-driver layer with WanderAir/Sense)
• Learning algorithm: simple decision-tree + occupancy-fused PID (NOT FPGrowth — see D-04 below; FPGrowth is wrong tool for thermostat schedule learning, would over-fit + waste PSRAM)
• Fail-safe firmware: if MCU panics, watchdog hardware-resets; relays default to user-configured "safe" state (heat off in summer profile / heat-low in winter profile per identity-aware preset)
• Secure boot + signed OTA — required by UL 60730 software-controls clause (Class B software per IEC 60730-1 Annex H)
• Covert mode firmware: rebrands SSID + mDNS + Matter advert string to generic "T-STAT-XXXX"; suppresses saffron LED arc; e-ink shows generic Honeywell-style numeric display only [rule: identity-aware]
• Duress code: 5-digit code entered via bezel-rotate (digit-spin like a combination lock); silently triggers configured action (e.g., open WanderNode Hub safehouse-alert workflow, blank app history, route phone-app login to decoy state) — local-only, never leaves device unless user has WanderNode Hub configured to receive [rule: identity-aware]

Stage 10 — Gate review + service flow (2026-04-24)

• HARD GATES at launch: UL 60730-1 + UL 60730-2-9 + AHRI 1380 + Matter 1.3+ + 24V isolation hipot + OpenTherm interop (Pro)
• See GATE.md + SERVICE-FLOW.md

---

Critical design decisions — rationale + references

D-01: Round e-ink display, NOT round LCD — why (LOCKED)

• E-ink is sub-µA standby vs ~50mA backlit LCD → critical for power-stealing no-C-wire installs (~5-10% of US homes)
• Zero burn-in over 7-year warranty
• Perfect off-axis readability (wall-mount viewing angle)
• Saffron arc rendering: 4-bit greyscale e-ink supports the rendered saffron arc indicator (only when heating active, persisted with zero refresh power)
• Trade-off accepted: ~1 sec refresh latency (vs LCD's 16ms); fine for setpoint UI; not a problem for room temperature display [rule: 7yr-parts]

D-02: Cream-anodized aluminum case + saffron pinstripe — why (LOCKED, image-anchored)

• Aluminum acts as RF EM shield + heatsink + premium feel
• Cream anodize: differentiates from Nest's polished metal-mirror (more institutional) and ecobee's matte-black plastic (more office-product)
• Saffron pinstripe along the outer bezel: WanderVerse identity marker that does NOT read as a wordmark to a non-WanderVerse-aware viewer (covert-mode-compatible by default)
• 100mm diameter × 30mm depth: fits standard US 4×4 single-gang + 2×4 round wallplate; deep enough for OpenTherm + relay matrix; not Nest-shaped (Nest 4th gen is 110mm dome; ours is shorter cylinder + flat face) [rule: saffron, identity-aware]

D-03: NO exterior wordmark + covert mode default-on — why

• Image: "no exterior wordmark, NOT Nest-shaped"
• Survivors / undocumented households / abuse-pattern situations need a thermostat that looks generic to a hostile co-resident or LE walking through
• Default ships with covert mode AVAILABLE-but-not-enabled; identity-aware checkout flag enables it for users who declare survivor / undocumented / sex-worker / activist / journalist context
• Saffron arc + cream finish read as "tasteful European thermostat" to anyone unfamiliar with WanderVerse [rule: identity-aware]

D-04: Decision-tree + PID, NOT FPGrowth — why (correcting draft)

• Local-LLM draft mentioned FPGrowth as a candidate "learning algorithm." This is the wrong tool.
• FPGrowth is a frequent-itemset / association-rule mining algorithm — appropriate for "users who buy X also buy Y," not for thermostat schedule learning
• Thermostat schedule learning is well-served by: (a) occupancy-fused PID for setpoint tracking, (b) simple decision-tree (CART or random-forest) on (time-of-day, day-of-week, occupancy, outdoor-temp) → setpoint preferences, (c) a Bayesian update of "schedule confidence" over the first 14 days of use
• This is the architecture in Nest's first-gen learning thermostat papers (2011-2013) and ecobee's research (2018) — NOT FPGrowth
• PSRAM cost: tree fits in ~200 KB; FPGrowth would have needed ~2-4 MB and produced worse decisions
• LOCKED: decision-tree + PID + 14-day Bayesian schedule confidence

D-05: OpenTherm support is firmware-flag-enabled, hardware-shared — why

• Both Standard and Pro ship with the OpenTherm transceiver hardware on-board (BOM cost ~$3.20)
• Standard ships with OpenTherm firmware flag DISABLED to keep US-market UX simple
• Pro ships with the flag ENABLED for European boiler installs
• Cross-shipping: a US Standard customer who later moves to EU can enable OpenTherm via firmware flag (free)
• Avoids fragmenting hardware SKU between regions; shares cert lab work; cleaner SKU matrix

D-06: 7-year e-ink panel + face-plate-replaceable color swap — why

• E-ink panel rated 1M write cycles; at typical 3-state-changes-per-day usage, that's ~900 years (limit is panel lifetime, not write count)
• Replaceable face plate (cream/slate) for color-swap or after cosmetic damage; magnetic snap-fit + T5 Torx capture; user-DIY 60-second swap
• 7-year structural parts include: PCB, MCU, e-ink panel, OpenTherm IC, relay matrix, BME688, TMP117, MTCH6303, TPS65086100, chassis, magnetic face panel, install bracket
• Consumables NOT in 7-year: CR2477 coin cell (replaceable as needed), face-plate cosmetic finish (color-swap is cosmetic upgrade, not warranty)

D-07: Identity-aware defaults — survivor / undocumented / hostile-state

• Covert mode (D-03 above) — generic thermostat appearance + SSID + Matter advert
• Duress code on bezel-rotate UI — 5-digit code that silently triggers a user-configured "if I am being forced to disclose, do this" workflow (could be: route to decoy WanderVerse profile, alert WanderNode Hub safehouse, blank phone app history)
• No remote-temperature broadcast in covert mode — unit reports only on local network, never to a public mDNS scan
• Local-only learning data — schedule + occupancy never leaves device unless user explicitly opts in to cloud backup (iCloud / GDrive / Nextcloud / S3 with user-supplied keys)
• HAVEN safehouse preset — multi-occupant tolerance (higher CO2/RH thresholds) + admin-only WiFi config + auto-arming covert mode on factory reset

D-08: 60/30/10 Community Pool feed

• Per WANDERVERSE-COMMUNITY-POOL-SPEC.md:
• 60% → Ambassador wages
• 10% → PrideFund HYSA
• 30% → WWP Community Pool (Layer 1 ≤65% ops, Layer 2 ≥35% Ambassador-voted)
• Per-unit Community Pool contribution at $179 Standard with ~$72 FOB = ~$32 per unit (30% of $107 gross)
• Per-unit Community Pool at $279 Pro with ~$118 FOB = ~$48 per unit (30% of $161 gross)

---

Stage-by-stage sign-off

Stage	Status	Notes
0 — Feature-parity	✅	`_COMPETITIVE-AUDIT-2026-04-24.md`
1 — Intake + freeze	✅	`_MANIFEST.md`; 2-tier locked (collapsed from draft 4-tier)
2 — Component selection	✅	ESP32-S3 + BME688 + TMP117 + Cree saffron + GoodDisplay e-ink + Omron relays
2b — Configurator	✅	`CONFIGURATOR.md`
3 — Compatibility	✅	`COMPATIBILITY.md`
4 — Sourcing	✅	`SOURCING.csv`
5 — DFM/DFA/DFT	✅	`DFM-DFA-DFT.md` — Ambassador time + UL hipot + 24V isolation
6 — Thermal/EMC	✅	`THERMAL-EMC.md`
7 — Compliance	✅	`COMPLIANCE.md` — UL 60730 + AHRI 1380 + Matter
8 — Canonical BOM + GUIDE + STLs	✅	BOMs + GUIDE + STL-OPEN-FILES/
9 — HW↔FW	✅	`HW-FW.md`
10 — Gate review + service	✅	`GATE.md` + `SERVICE-FLOW.md`

---

Critical open items carried forward

#	Item	Severity	Owner	Target
1	UL 60730-1 + UL 60730-2-9 lab booking (Intertek Chicago or UL Northbrook)	🔴	Cert team	2027-Q1
2	AHRI 1380 smart thermostat performance test (AHRI-accredited lab)	🔴	Cert team	2027-Q1
3	OpenTherm interop validation across Vaillant / Viessmann / Worcester-Bosch / Junkers	🟡	Eng + EU partner	2027-Q1 EVT trip
4	GoodDisplay 1.54" round e-ink supply commitment + 7-yr availability	🟡	Sourcing	2026-Q4
5	Decision-tree learning model 14-day field validation (10 alpha users)	🟡	FW + Product	2027-Q2 DVT
6	Power-stealing no-C-wire validation across heat-pump + furnace + boiler installs	🟡	Eng	2027-Q1 EVT
7	Matter `Thermostat` cluster CSA cert (shared with WanderRouter HVAC features)	🟡	Cert	2027-Q1
8	Energy Star Connected Thermostat v1.0 application	🟡	Cert	2027-Q3
9	Contract manufacturer PCBA + chassis + Ambassador final assembly	🔴	Ops	2026-Q4
10	Covert mode firmware audit — verify SSID + mDNS + Matter advert all suppress correctly	🟡	FW + security review	2027-Q2
11	Duress code workflow — WanderNode Hub integration spec	🟡	FW + WanderNode team	2027-Q2
12	Coin-cell CR2477 7-year availability + alt-source qualification	🟢	Sourcing	2026-Q4
13	HAVEN deployment field guide + Ambassador on-site training	🟡	WWP + Training	2027-Q4
14	ESPHome upstream `wandertherm` component PR	🟢	FW	2026-Q4
15	EU CE EN 60730 + boiler interop cert (Pro tier OpenTherm)	🟡	Cert + Eng	2027-Q3
16	Identity-aware defaults audit on every shipping firmware build	🟡	Security + QA	ongoing
17	24V isolation hipot fixture design (1500 VAC per UL 60730-1 §H.27)	🟡	DFT	2026-Q4