future-plans: clarify SI prefix vs unit distinction

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

future-plans.md

@@ -132,11 +132,17 @@ dimension (e.g. `temperature`, `resistance`, `frequency`, `voltage`). The dimens
 defines the set of valid units and the conversion factors between them (°C, °K, °R,
 °F for temperature; Ω, kΩ, MΩ for resistance; etc.).
 
+SI prefixes (k, M, µ, n, p, etc.) are not separate units — they are a presentation
+layer on top of a unit. `25kΩ` should be parsed as value `25000`, prefix `k`, unit
+`Ω`, and stored as `{ value: 25000, unit: "Ω" }` (or in a canonical base unit).
+The prefix is re-applied on display based on the magnitude. This keeps comparisons
+and conversions clean without treating kΩ and MΩ as distinct unit types.
+
 This would allow:
-- Entering values in any compatible unit and storing in a canonical unit internally
-- Displaying in the user's preferred unit
-- Parametric search with cross-unit comparisons (e.g. `temp_range > 200K` matching
-  a component with `temp_range = -73°C`)
+- Entering values in any compatible unit and SI prefix, storing canonically
+- Displaying in the user's preferred unit and auto-selecting an appropriate prefix
+- Parametric search with cross-unit and cross-prefix comparisons (e.g. `R < 10k`
+  matching both `4k7Ω` and `0.001MΩ`)
 - Catching unit mismatches at entry time
 
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