# lib-core.selection — v0.1.0

Click-Select + Drag-Box-Select + Selection-Set-State.

## Quick Setup

```lua
local selection = require("lib-core.selection")
local input     = require("lib-core.input")

input.bind("lmb",        { "mouse_left" })
input.bind("mod_add",    { "shift" })
input.bind("mod_toggle", { "ctrl" })

selection.bind_action("lmb")
selection.bind_modifier_add("mod_add")
selection.bind_modifier_toggle("mod_toggle")

local handle = selection.register(function()
    return { x = entity.x, y = entity.y, w = entity.w, h = entity.h }
end)

-- per-frame:
function update(ctx, dt)  selection.update(dt)  end
function render(ctx)
    camera.begin()
        -- entities…
        selection.render_highlights()    -- world-space
    camera.finish()
    selection.render_drag_box()          -- screen-space
end
```

## API

- Registry: `register(aabb_fn) → handle`, `unregister(h)`, `count_registered()`
- Set-Query: `list()`, `count()`, `contains(h)`, `is_empty()`
- Set-Mutation: `add(h)`, `remove(h)`, `toggle(h)`, `clear()`
- Bindings: `bind_action(name)`, `bind_modifier_add(name)`, `bind_modifier_toggle(name)`
- State-Config: `set_drag_threshold(px)` / `drag_threshold()`, `set_enabled(bool)` / `enabled()`
- State-Query: `drag_state() → "idle"|"ambiguous"|"dragging"`, `box_rect() → {x,y,w,h}|nil`
- Visual: `set_drag_box_color(r,g,b,a)` / `drag_box_color()`, `set_highlight_color(r,g,b,a)` / `highlight_color()`
- Per-Frame: `update(dt)`, `render_drag_box()`, `render_highlights()`

See `meta/docs/superpowers/specs/2026-05-14-p3-6-lib-selection-design.md` for full design.