# `MingaEditor.Layout.OverlayBand`
[🔗](https://github.com/jsmestad/minga/blob/main/lib/minga_editor/layout/overlay_band.ex#L1)

Shared footer-band geometry for the single-active secondary overlays (#2281).

The Go compositor historically footer-appended one secondary overlay at the
bottom of the screen, sizing its height with `maxOverlayHeight()`
(`go/tui/internal/ui/model.go`: `min(max(height/3, 4), 12)`) and spanning the
full terminal width. These eight surfaces (float popup, agent context, tool
manager, extension panel, observatory, edit timeline, notifications, extension
overlay) are identical footer-band shapes, so the BEAM owns one rect helper for
all of them instead of eight copies.

`rect/2` ports that exact clamp. `content_height` is the surface's content line
count (BEAM-derivable from the chrome/UI models) or `:max` for a surface whose
wrapped line count the BEAM cannot know. The rect is bottom-anchored: it occupies
the lowest `height` rows of the terminal and the full width, the same band the
frontend appended into, so the rect's bottom edge sits where the old footer-append
put the overlay (directly above the minibuffer).

Only one overlay shows at a time in that band (single-active model, #2268 AC-4).
For the count-derivable surfaces (notifications, observatory, edit_timeline,
extension_overlay) the caller passes a real `content_height` so the band shrinks
to the content and the overlay hugs the screen bottom. For the wrap-dependent
surfaces (float_popup, extension_panel, and the dormant agent_context/tool_manager)
the caller passes `:max` (the clamp ceiling); the frontend bottom-aligns the
rendered content inside that band, so a short overlay still hugs the bottom and
the residual phantom rows sit ABOVE it (see `MingaEditor.Layout.FooterOverlays`).
Either way the rect only needs to CONTAIN the overlay so clicks over it are
hit-tested, not pixel-match it.

# `band_height`

```elixir
@spec band_height(non_neg_integer(), non_neg_integer() | :max) :: non_neg_integer()
```

Returns the clamped footer-band height for a content line count.

Ports the Go `maxOverlayHeight()` clamp: the band is `terminal_rows / 3`,
floored at 4 and ceiled at 12, and never taller
than the content it must contain. Passing `:max` for `content_height` yields
the clamp ceiling directly, the conservative size for a text-wrap-dependent
surface whose exact wrapped line count the BEAM cannot know.

# `rect`

```elixir
@spec rect(MingaEditor.Layout.rect(), non_neg_integer() | :max) ::
  MingaEditor.Layout.rect() | nil
```

Returns the bottom-anchored, full-width footer-band rect for an overlay.

`content_height` is the surface's content line count (or `:max` to take the
clamp ceiling for a text-wrap-dependent surface). The rect spans the full
terminal width and the lowest `band_height/2` rows, matching where the Go
compositor footer-appended the overlay. Returns `nil` when the band would be
empty (zero content and zero clamp floor never happens, but a degenerate
terminal can produce a zero-height band).

---

*Consult [api-reference.md](api-reference.md) for complete listing*