Module name_field 

A one-line, in-place text field for naming something.

Both history surfaces need the same small thing: a field that appears where the name will live, takes the keyboard while it is up, commits on Enter and abandons on Escape. The activity pane grows it inside a band header; the word processor’s strip grows it in the button row. Writing it twice would mean two sets of key handling, two truncation rules, and two carets that drift apart — so it is one primitive.

It is not a general-purpose text input: no selection, no clipboard, no caret movement — those belong to TextInput, which is far too much machinery for a label a user types once. Its typing, grapheme-wise Backspace and IME composition still go through the shared EditCore, so it erases and composes exactly like every other field. What this does have is the behaviour a name field must not get wrong:

• It keeps the tail visible when the text outruns the box, because what the user is typing is at the end.
• Enter and Escape are consumed, so a host cannot accidentally also act on them.
• An empty commit is reported as an empty string rather than swallowed: over an existing name that means “remove it”, and only the host knows whether there is one.

Structs

NameField

A one-line name field. Hosts own the placement and the lifetime; this owns the text and the keys.

Enums

NameFieldOutcome

What a key did to the field.

Functions

fit

Shorten s until it fits budget pixels in style, appending an ellipsis when anything was dropped.

fit_tail

Keep the tail of s. What a person is typing is at the end, so a field that has run out of room drops the beginning, not the caret.