Decision D7 · 7 of 21
Fast-loop message channel
WhatsApp plus a local Plant Box display
RECOMMENDED
- Status
- RECOMMENDED — awaiting Vinayak
- Options
- WhatsApp only; plant HMI tile or andon; local display on the Plant Box
- Trade-offs
- WhatsApp needs internet; HMI integration needs vendor work
- Recommendation
- WhatsApp from the single L5 sender for people away from the line, plus a local display served by the Plant Box for the line itself. HMI tiles are later, per plant, when a vendor integration is cheap.
- Why
- WhatsApp needs internet; the local display does not. Both read the same card from L5, so there is still one sender and one budget.
- Evidence
- section 2.3 WhatsApp duplication; section 7.1 placement (operator messages need a local fallback).
- Reversible
- Yes. Channels are renderers of one card.
- Blocks
- Degraded mode for WAN loss; AL1 messages in the fast loop.
Page history: last 2 changes
- docs(research): retire stale research to archive/research-2026-10 with a register
ab84821 - docs(technical): split decision board into DECISIONS.md
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