Previously CellValue had three variants: Number, Text, and Empty.
The Empty variant acted as a null sentinel, but the compiler could not
distinguish between "this is a real value" and "this might be empty".
Code that received a CellValue could use it without checking for Empty,
because there was no type-level enforcement.
Now CellValue has only Number and Text. The absence of a value is
represented as None at every API boundary:
DataStore::get() → Option<&CellValue> (was &CellValue / Empty)
Model::get_cell() → Option<&CellValue> (was &CellValue / Empty)
Model::evaluate() → Option<CellValue> (was CellValue::Empty)
eval_formula() → Option<CellValue> (was CellValue::Empty)
Model gains clear_cell() for explicit key removal; ClearCell dispatch
calls it instead of set_cell(key, CellValue::Empty).
The compiler now forces every caller of evaluate/get_cell to handle
the None case explicitly — accidental use of an empty value as if it
were real is caught at compile time rather than silently computing
wrong results.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Axis::Unassigned served two purposes that Option already covers:
1. "this category has no assignment yet" → None
2. "this category doesn't exist" → None
By removing the variant and changing axis_of to return Option<Axis>,
callers are forced by the compiler to handle the absent-category case
explicitly (via match or unwrap_or), rather than silently treating it
like a real axis value.
SetAxis { axis: String } also upgraded to SetAxis { axis: Axis }.
Previously, constructing SetAxis with an invalid string (e.g. "diagonal")
would compile and then silently fail at dispatch. Now the type only admits
valid axis values; the dispatch string-parser is gone.
Axis gains #[serde(rename_all = "lowercase")] so existing JSON command
files (smoke.jsonl, etc.) using "row"/"column"/"page" continue to work.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Three copies of cross_product existed (grid.rs, app.rs, persistence/mod.rs)
with slightly different signatures. Extracted into GridLayout in
src/view/layout.rs, which is now the single canonical mapping from a View
to a 2-D grid: row/col counts, labels, and cell_key(row, col) → CellKey.
All consumers updated to use GridLayout::new(model, view):
- grid.rs: render_grid, total-row computation, page bar
- persistence/mod.rs: export_csv
- app.rs: move_selection, jump_to_last_row/col, scroll_rows,
search_navigate, selected_cell_key
Also includes two app.rs UI bug fixes that were discovered while
refactoring:
- Ctrl+Arrow tile movement was unreachable (shadowed by plain arrow arms);
moved before plain arrow handlers
- RemoveFormula dispatch now passes target_category (required by the
formula management fix in the previous commit)
GridLayout has 6 unit tests covering counts, label formatting, cell_key
correctness, out-of-bounds, page coord inclusion, and evaluate round-trip.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
