# Torch Crew Node engineering brief

## Purpose
Jack is Torch's field intelligence assistant for tradespeople. Site internet reception can be unreliable. This node is a local communications middleman for phones and other nodes, carrying small crew presence/status messages and store-and-forward events. It does not run Jack's language model, create internet access, or establish precise worker location.

## Hardware scope
- ESP32-C6 module, prefer a supported module rather than bare-chip RF design. BLE phone link and 802.15.4/Thread node link are candidate firmware roles; assess shared-radio coexistence and limitations. Wi-Fi available for configuration/gateway experiments. No assumption of three independent concurrent radios.
- USB-C 5 V power and programming/debug, with correct USB-C sink configuration and appropriate ESD protection. No need for USB PD.
- Rechargeable single-cell Li-ion/LiPo supply: charging, battery protection, temperature-aware charging where supported, load sharing/power path for operation while charging, appropriate 3.3 V regulation with RF peak-current margin. Specify compatible battery characteristics, connector polarity and justified charge-current assumptions. External battery acceptable.
- Low-power status indicator and one accessible user button. Add boot/reset access as required for reliable recovery/programming.
- Antenna arrangement suitable for portable enclosure; choose and justify module antenna versus external antenna connector. Preserve antenna keepout and battery/enclosure clearance in later layout. No claimed range through concrete or steel.
- Expansion connector(s) exposing suitable 3.3 V interfaces and control pins for optional LoRa or UWB daughterboards later. Neither radio needs population in this first revision. Document GPIO constraints, current limits and intended connector pinout; do not imply universal module compatibility.
- Suitable flash capacity for firmware and a bounded event queue; specify limits. Hardware security features should support authenticated enrollment, signed firmware and protected stored data, but firmware implementation is a separate deliverable.
- Test points for supply rails and useful debug signals. Portable, enclosure-friendly board with mounting provision. No founder-fixed dimensions or battery capacity: propose pragmatic prototype assumptions and label them.

## Engineering priorities
Prefer available, economical standard parts, simple assembly and an inspectable prototype. No committed price or runtime target exists: estimate with assumptions instead of claiming measured values. Separate powered relay duty from low-power crew-node duty. A few off-the-shelf dev boards should prove phone-to-node-to-node communications before manufacturing a custom PCB.

## Subsequent milestones for context
After schematic review: PCB placement/routing and electrical/layout review, then BOM/design files and a prototype test plan. Tests must cover power/charge/thermal behavior, BLE plus node-link coexistence, phone background/reconnect behavior, delivery/duplicates/expiry, complete internet loss, relay failure, measured multi-floor coverage and battery runtime. UWB positioning and LoRa are optional future investigations. No manufacturing order, production reliability or safety certification is implied by design completion.