Slice 10 b2: UiSurface list/container data bindings

The stage dock is one RML document rendering a variable list of slots (one per
minimized window). Adds the deferred slice-6 list-binding shape to UiSurface:
bind_list(name, count) + typed per-row fields bind_list_string/int/double/bool
(list, field, getter(row)) read as {{ row.field }} via data-for, and
bind_list_event(list, event, callback(row)) routed from data-event-*(it_index).
dirty(<list>) re-reads count + visible rows. Same error-isolation + bind-before-
first-frame contract as the scalar bindings; nested lists unsupported.

kernel suite green on build + build-asan (asan clean). Edits confined to packages/kernel/.

1 files changed, 17 insertions, 0 deletions

diff --git a/packages/kernel/src/ui_substrate.hpp b/packages/kernel/src/ui_substrate.hpp
index cdba997..33dfd4e 100644
--- a/packages/kernel/src/ui_substrate.hpp
+++ b/packages/kernel/src/ui_substrate.hpp
@@ -97,6 +97,17 @@ public:
     void bind_bool(std::string_view name, std::function<bool()> getter) override;
     void bind_string(std::string_view name, std::function<std::string()> getter) override;
     void bind_event(std::string_view name, std::function<void()> callback) override;
+    void bind_list(std::string_view name, std::function<std::size_t()> count) override;
+    void bind_list_string(std::string_view list, std::string_view field,
+                          std::function<std::string(std::size_t)> getter) override;
+    void bind_list_int(std::string_view list, std::string_view field,
+                       std::function<int(std::size_t)> getter) override;
+    void bind_list_double(std::string_view list, std::string_view field,
+                          std::function<double(std::size_t)> getter) override;
+    void bind_list_bool(std::string_view list, std::string_view field,
+                        std::function<bool(std::size_t)> getter) override;
+    void bind_list_event(std::string_view list, std::string_view event,
+                         std::function<void(std::size_t)> callback) override;
     void on_touch_mode_changed(std::function<void(bool)> callback) override;
     void dirty(std::string_view name) override;
     void dirty() override;
@@ -178,6 +189,12 @@ public:
     // / out of bounds. A position-aware probe (like orientation()) so the suite
     // can assert a preview's known source color landed at the expected spot.
     [[nodiscard]] auto surface_pixel(int x, int y) const -> std::uint32_t;
+    // Count elements with `tag` in the first surface's loaded document (0 if no
+    // surface / not loaded yet). Proves a data-for list rendered N rows.
+    [[nodiscard]] auto element_count(const char* tag) const -> int;
+    // Click the index-th `tag` element in the first surface's document (fires
+    // its data-event-click). False if no such element. Drives a row event.
+    auto click_element(const char* tag, int index) -> bool;
 
     struct Impl;