Q-W1 pt2: core/shell/app relocation + sub-namespaces; one concrete ui::Rect (LTRB fork retired); slot_map split from bank_book; BankIndex→BankModel; 59/59 green

src/core/ui/prune_button.h

@@ -0,0 +1,82 @@
+#pragma once
+#include "core/ui/rect.h"
+// prune_button — the REAPER-free layout math behind the bank_panel's Prune button
+// (Phase R, Wave 3 — R3, fork R-E). A single labelled button drawn in the panel's
+// tail-footer strip that fires the "Prune bank folder" command. The panel shell
+// (bank_panel.cpp) owns the SWELL window, LICE drawing, and the Main_OnCommand
+// dispatch of the registered command id — all REAPER-bound, DAW-verified. What is
+// NOT DAW-bound — WHERE the button sits in the footer and whether a click lands on
+// it — lives here so it is unit-tested outside the DAW (CLAUDE.md §load-bearing
+// split). Mirror of mode_switch / tab_strip.
+//
+// PURE MODULE: NO REAPER types, NO SWELL, NO vendor/ includes. Standard library
+// only. Builds and unit-tests without REAPER.
+//
+// -- Placement contract --------------------------------------------------------
+//
+// The footer hosts (L4) a LEFT group — the [Arrange|Design] mode toggle, a per-mode
+// count, and the Tail button (bank_panel footer_bar) — and a RIGHT-aligned version
+// readout (bank_panel drawFooter). The prune button is a fixed-width button anchored
+// to the RIGHT of the footer, inset from the right edge, sitting just LEFT of the
+// version readout's inset region and set APART from the benign left group. It never
+// overlaps the left group (footer_bar reserves rightReserve px at the right to match).
+// When the footer is too narrow to fit the button without colliding with the left
+// inset, the button is suppressed (empty rect) rather than drawn on top — the action
+// is always reachable via its bindable command, so a hidden button is a graceful
+// degradation, not a lost affordance.
+
+namespace reasampler::ui {
+
+// The footer strip the button is drawn into, top-left origin (SWELL/LICE
+// convention). (x, y) is the top-left corner; width/height are the strip extents.
+// bank_panel derives this from panelFooter() and passes it here.
+using FooterRect = Rect;  // Q-W1: the shared concrete ui::Rect (core/ui/rect.h), role-aliased
+
+// A button's pixel rectangle within the footer, top-left origin. A zero-area rect
+// (width <= 0 or height <= 0) means "no button" — the footer is too narrow to place
+// it, or the footer itself is degenerate; the caller must not draw or hit-test it.
+using ButtonRect = Rect;  // Q-W1: the shared concrete ui::Rect (core/ui/rect.h), role-aliased
+
+// Layout inputs for the prune button, in pixels. Defaults match the bank_panel footer
+// metrics; the shell passes its own so draw and hit-test share one source of truth.
+//   * buttonWidth   — the button's fixed width.
+//   * rightInset    — gap from the footer's right edge to the button's right edge (the
+//                     button sits left of this inset, clearing the right-aligned version
+//                     readout). COUPLED TO drawFooter (bank_panel.cpp): the version readout
+//                     uses an 8 px right margin. The button's right edge lands at
+//                     footer.right - 84, i.e. 76 px left of the readout's right margin —
+//                     enough clearance for the ~10-char label. ALSO COUPLED to
+//                     FooterBarSpec::rightReserve (footer_bar.h): the L4 footer-left group
+//                     (mode toggle + count + Tail) reserves that many px at the right so it
+//                     never runs under this button; rightReserve must exceed rightInset +
+//                     buttonWidth. If the version readout's inset changes in drawFooter,
+//                     update this value to maintain clearance.
+//   * verticalInset — top/bottom gap inside the footer (the button is shorter than the
+//                     strip so it reads as a raised control, not a full-height fill).
+//   * minLeftInset  — the button's left edge must stay at least this far from the footer
+//                     left edge (reserving room for the L4 footer-left group). If the button
+//                     would encroach past this, computePruneButton yields an empty rect
+//                     (button suppressed — see header placement contract).
+struct PruneButtonSpec {
+    int buttonWidth = 72;
+    int rightInset = 84;  // COUPLED: version readout in drawFooter uses an 8 px right margin
+    int verticalInset = 4;
+    int minLeftInset = 120;
+};
+
+// Computes the prune button's rect within `footer` per `spec`. Right-anchored: the
+// button's right edge is footer.x + footer.width - rightInset, its width is buttonWidth,
+// and it is vertically centred by verticalInset. Returns an EMPTY rect (button
+// suppressed) when: the footer is degenerate (width/height <= 0), OR the resulting left
+// edge would fall closer to the footer left than minLeftInset (too narrow to place
+// without colliding with the tail label). The action stays reachable via its command in
+// that case — a suppressed button is graceful, not a lost feature.
+ButtonRect computePruneButton(const FooterRect& footer, const PruneButtonSpec& spec);
+
+// True iff the point (px, py) (SWELL/LICE top-left client coords) falls inside `button`.
+// Half-open bounds [x, x+width) x [y, y+height) — matches computePruneButton so draw and
+// hit-test agree on the same pixels. An empty button never claims a point (always false),
+// so a suppressed button cannot be accidentally clicked.
+bool hitTestPruneButton(int px, int py, const ButtonRect& button);
+
+} // namespace reasampler::ui