future-plans: store measurement as {value, prefix, unit}, canonical only for queries

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

future-plans.md

@@ -133,16 +133,19 @@ defines the set of valid units and the conversion factors between them (°C, °K
 °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.
+layer on top of a unit. `25kΩ` should be stored as
+`{ value: "25", prefix: "k", unit: "Ω" }` — preserving the original string value
+and prefix exactly as entered, so no precision or notation is lost.
+
+A canonical numeric form is derived from the stored triple only when needed for
+comparison or search queries (e.g. `R < 10k` → compare canonical floats). Display
+always reconstructs from the stored `value + prefix + unit`, so `4k7` stays `4k7`
+and `25.0` stays `25.0`.
 
 This would allow:
-- 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`)
+- Lossless storage of entered values (significant digits, notation style preserved)
+- Parametric search with cross-prefix comparisons via derived canonical values
+- Unit conversion on query (e.g. `temp > 200K` matching a stored `-73°C`)
 - Catching unit mismatches at entry time
 
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