GridCraft keeps workbook data in hidden defined names so it travels
inside the xlsx file. The existing items write one name holding one
string literal, which past Excel's 255-character literal and
8,192-character formula limits gives a file Excel does not accept.
cmd/stash.rs stores an item `key` as hidden workbook-scope names
_gc_<key>_0, _gc_<key>_1, ..., each a formula of string literals of at
most 255 characters (UTF-16 units, as Excel counts them) joined with &,
at most 8,192 characters per name. Reading concatenates the chunks in
order and stops at a gap; it also accepts the older single _sc_<key>
name. Names are matched case-insensitively and only at workbook scope.
Keys are limited to letters, digits, _ and ., items to 4,194,304
characters, and junk around or inside the literals, duplicate or
out-of-order chunks, non-JSON and over-deep JSON all read safely.
keys(prefix) lists the stored items that start with a prefix.
Custom views, scripts, the watch list and scenarios keep their current
storage; nothing reads or writes the new names yet.
docs/architecture.md describes the engine building blocks added in this
series: undo groups, the recording buffer, document trust and this
storage.
Progress docs per craftrules standards/progress-docs.md: target-app parity, gaps, roadmap with alpha gate, readiness by audience (full / mainstream / essentials) with Opus 5.5 hours, and feature, format, hardware, UI and localization parity docs.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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