nordisk/facett

facett-tabbar — crate card

Reverse-engineered (from source — verify, don't trust the name)

• One-line pitch: The generic themed 2-row nav toolbar — a control strip (pickers/toggles/buttons) + a two-row strip of tab headers with the active tab carrying the palette accent.
• Does: Two surfaces. TabBar<'a> — a borrowed, zero-alloc widget (&[TabItem] + an active id); show()/show_anim() return the id of the newly-clicked tab (UnderlineTween animates the accent); state_json() reports tabs/active/split/controls; supports split_at and BarControls (picker/toggle/button). TabBarView — an owning canonical Facet (local()/remote()/state_json()/caps()) that tracks its own active, re-keys on click, and counts switches. TabItem keeps id (click/state_json) separate from label (painted). Verbatim port of nornir's facett_ui.rs bar.
• Key deps: facett-core (Facet, theme), egui, serde/serde_json.
• Shape: lib, single module (~585 lines). Key types: TabItem, BarControl, TabBar<'a>, UnderlineTween, TabBarView.
• Observed role in the workspace: The re-home of nornir's top-bar; nornir re-points to it once its viz clears the egui-snarl 0.33→0.34 pin.

Fill in (one line each — only the human knows these)

• Primary consumer(s):
• Why it exists (vs the obvious alternative):
• Hard constraint (airgap / no-C-deps / no-FFI / pure-Rust / etc.):
• Release cadence & independence (rides a parent? own repo someday?):
• Status (production / prototype / experimental / stubbed):
• Must-NOT-change invariant:
• Biggest known gap or TODO:
• Anything a newcomer would get wrong about it: