Prototype roadmap

1. Prove one sensing channel

Verify the intended divider voltage against the ADC configuration, then measure empty, known resistor, unstable contact, and unknown-resistor readings. Repeated placement should produce separable bands before assigning identities.

2. Prove one complete hex

Resolve the CH32 input/peripheral pin budget and preserve programming access. Exercise all seven analog channels, robber debounce, local OLED rendering, and shared-bus communication together. Measure memory use and power under the combined workload.

3. Enumerate seven hexes

Assemble the fixed chain. Define initial addressing and CHAIN behavior, then verify deterministic index assignment, repeatable startup, missing-device behavior, and restart recovery. Confirm each OLED is reached only through its owning hex.

4. Map the sensed board

Define local sensor orientation and global positions for the supported prototype subset. Check unique ownership and adjacency. Mark unsensed positions explicitly. Resolve how the full-board road deficit will be handled before scaling hardware.

5. Add diagnostic and calibration flows

Expose raw ADC, inferred resistance, classification, and device availability. Measure repeated real-piece placements, then define the registry and calibration storage behavior.

6. Integrate game behavior

Build a hardware-independent rules core with tests, connect physical observations through reconciliation, and add public and private web views. Verify legal/illegal actions, missing pieces, disconnects, and private-data separation.

7. Expand only after measurements

Use measured power, wiring reliability, ownership coverage, and firmware resource use to inform the 19-hex design. Remote firmware updates and automatic neighbour discovery require separate investigation; neither is necessary for the first prototype.

No dates or completed milestones are claimed. The open questions identify the details that block assembly-ready specifications.