Layout persists through derived keys and a stated reconciliation algorithm
Layout state (folder order and expansion, dock size and collapse, floating position, size and visibility) goes through a two-method StorageAdapter port. The default wraps localStorage and degrades to memory permanently on failure, at both points where it throws: reading the window.localStorage property in a sandboxed iframe, and setItem raising QuotaExceededError long after construction succeeded.
Keys derive from tag name plus a slug of the label, with declaration order breaking ties, and an explicit key always wins. The slug normalises rather than strips — NFD, drop combining marks, lowercase, collapse non-alphanumerics — because a naive strip turns "Rotation générale" into rotation-g-n-rale and gives "Échelle" and "Echelle" different keys for one label.
Reconciliation on load is stated as an algorithm, because "take their declared position" is ambiguous once a list has been reordered: keep stored order for keys still present, drop stored keys that are gone, then insert each present-but-unstored key immediately after its nearest surviving preceding sibling. Derivation and reconciliation are both pure functions over strings, so both are unit-tested without a DOM.
Considered Options
- Configuring a key per component. Too heavy for the common case; the costs below are all recoverable by setting
keyexplicitly. - Reordering by declaration index. Inserting one control scrambles every saved position after it.
- Auto keys from the label alone. Duplicate labels collide silently.
Consequences
Renaming a label or swapping a control's type drops that item's saved position. Occurrence suffixes renumber: with two Options folders, deleting the first promotes the survivor to …:options, inheriting the deleted item's saved position while its own entry is dropped as orphaned. "I removed an unrelated folder and another one moved" is a confusing symptom, so it is recorded here rather than discovered later. A development warning fires on a tie.