docs(principles): a front end displays state; it does not reimplement behaviour

User ruling 2026-09-20: minimise the amount of new code a new UI framework
needs. Centralise logic in a redux-like store so a second or third front end
is a function from state to pixels plus a wire for events, not a second
implementation of how the application behaves.

Names the pieces that already exist as what they are -- Command is the
action, reduce_view and WidgetCache::apply are the reducer, ViewState plus
the caches are the store, Sessions::apply is dispatch -- and gives the
question to ask of any front-end code: would a third front end have to write
this again?

Three things make it concrete: the measure is lines of framework-specific
code and should trend to 'paint and wire'; a derivation done twice is the
defect even when both copies are correct today (improvise-edp is the worked
example, gotcha 44 is the same defect still open); and sharing a table beats
testing two copies of it, which is why the keymap is shared rather than
mirrored. Also says what legitimately stays local: painting, event wiring,
and a semantic-value-to-framework-type lookup like AxisColor -> axis_fg.

Sections 5-7 renumbered; the §6 testing references in repo-map.md and the
code-review skill updated with them.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EoW5BB87ZZdm96SvBTWawH

This commit is contained in:

Edward Langley

2026-09-19 21:31:58 -07:00

parent db70bb161c

commit d175b9934f

4 changed files with 62 additions and 9 deletions

.beads/issues.jsonl

+4 -4

View File

File diff suppressed because one or more lines are too long