change redesign

docs/codesys/plc-algorithm-design.md

@@ -47,6 +47,32 @@ This document defines the PLC algorithms for the home automation system:
 
 ---
 
+## Light organization: do you need 6 per room?
+
+### Short answers
+
+- **Do you need exactly 6 predefined?** No. It’s a convenient maximum. Unused slots are fine (no relay wired). You can use a smaller max (e.g. 4) or a larger one (e.g. 8) if you prefer.
+- **Is room-based organization a good idea?** Yes. It matches how people think and how voice/HA work (“turn off bedroom”, “kitchen lights”). Keep organizing by room.
+- **Best approach:** Room-based with a **fixed max lights per room** (e.g. 6 or 8). Use only the slots you need; leave the rest logically “empty.” Optionally, use **named slots** per room (e.g. `main`, `bedside_left`) instead of `l_1`..`l_6` so the PLC matches your naming and you don’t “waste” slots mentally.
+
+### Options (trade-offs)
+
+| Approach | Description | Pros | Cons |
+|---------|-------------|------|------|
+| **A. Fixed N per room (current)** | Every room has e.g. 6 slots (`l_1`..`l_6`). Use only what you need. | Simple, same code for every room, easy Node-RED mapping. | Empty slots still in struct/UI; adding a 7th light in one room needs a new room or structure change. |
+| **B. Named slots per room** | Each room has semantic slots: `main`, `bedside_left`, `under_cabinet`, etc. (from `light-naming-configuration.md`). Not all rooms have all slots. | Clear meaning, matches your naming; “unused” is obvious. | More types or optional slots in CODESYS; Node-RED must know which rooms have which slots. |
+| **C. Flat list of lights** | One list of e.g. 64 lights; each has a relay index. Room exists only in HA/Node-RED. | No per-room limit; add lights by config. | “Turn off all kitchen” is done in HA/Node-RED (send OFF to each kitchen light). PLC doesn’t do room-level all_off. |
+
+### Recommendation
+
+- **Stay room-based** for control and UX.
+- **Keep a max per room (e.g. 6 or 8)** and accept that some slots are unused. No need to “predefine” exactly 6; think of it as “up to 6 (or 8) circuits per room.”
+- If you want the PLC to reflect real names, consider **B (named slots)** later: e.g. `struct_room_lights` with `main`, `bedside_left`, `bedside_right`, `closet`, … and only wire the ones that exist in that room. That’s a refinement of the same idea, not a different architecture.
+
+So: you don’t *need* 6 predefined; you need a *maximum* per room. Organizing by room is a good idea; the rest is how many slots per room and whether they’re named or generic.
+
+---
+
 ## Part 1: Lighting Control Algorithm
 
 **Alignment**: This section follows the structures and logic from **`docs/redesign/fb_switch-redesign-recommendation.md`**: flat `struct_switches` / `struct_lights`, `fb_lightControl` with HA ON/OFF + Zigbee toggle only, and `fb_switch` applying global commands by overwriting outputs.