feat: align timed drop activation semantics

Author: Roy Lin

README.md

@@ -75,9 +75,10 @@ versioned [component matrix](docs/react-aria-component-matrix.json) pins
   share the same RSX contract. External `onInsert`/`onRootDrop`, internal
   `onMove`, same-parent `onReorder`, multi-callback routing, equivalent adjacent
   boundaries, and self/descendant guards now follow the React Aria collection
-  policy; dynamic acceptance, OS/cross-application transfer, previews, pixels,
-  accessibility, and real hosts still keep every affected family below
-  conformance;
+  policy. Ordinary targets and collection items also share the exact 800ms
+  `onDropActivate` hold lifecycle across pointer and keyboard drags; dynamic
+  acceptance, OS/cross-application transfer, previews, pixels, accessibility,
+  and real hosts still keep every affected family below conformance;
 - Checkbox, Radio, and Switch Field/Button parts plus ToastList and
   ToastContent are recorded as eight explicit API gaps;
 - a component reaches `conformant` only with behavior, layout/hit, Graphics
@@ -315,9 +316,11 @@ independently.
   and root drops from internal move/reorder, rejects self and descendant
   targets, and preserves one logical boundary between adjacent items. A
   collection is one keyboard Tab stop during a drag, with arrow/Home/End
-  navigation inside it; all paths share event-loop deadlines, stable action
-  bubbling, keyed reconciliation, and reducer rollback in one staged
-  interaction session
+  navigation inside it. Valid ordinary targets and collection items schedule
+  one React Aria-compatible `DropActivate` after 800ms without delaying the
+  deadline as the pointer moves inside the same target; all paths share
+  event-loop deadlines, stable action bubbling, keyed reconciliation, and
+  reducer rollback in one staged interaction session
 - an identical-frame fast path that performs no layout, scene, host, or
   presentation work, plus semantic-only commits that skip pixel presentation
 - a software Graphics presenter and interactive shared
@@ -333,9 +336,9 @@ independently.
 | M1 · GUI integration | Complete | Pinned Graphics boundary, semantic-only dependency gate, renderer inventory, reference/GPU wrappers, first generic adapter |
 | M2 · GPU backend | Implementation landed | Graphics commit `8748fab`; Metal and Vulkan CI parity evidence remains |
 | M3 · Layout and Scene | Current | Generic calculator rectangle slice landed; full flex, stacking, redraw scheduling, cross-platform fingerprints, and thin-host presentation remain |
-| M4 · Text and interaction cutover | In progress | Stable-id raw input, long press, move, typed and collection drag/drop foundations landed; shaping, glyphs, editing/IME, accessibility bridges, overlays, and complete calculator scenarios remain |
+| M4 · Text and interaction cutover | In progress | Stable-id raw input, long press, move, typed and collection drag/drop plus timed drop activation landed; shaping, glyphs, editing/IME, accessibility bridges, overlays, and complete calculator scenarios remain |
 | M5 · Default cutover | Planned | Make self-drawn content the default, then delete the three legacy widget renderers |
-| H0-H5 · Thin platform hosts | H0 complete; H1 in progress | Atomic frames, lifecycle recovery, stable-id raw input/reducers, long press, captured move, typed drag/drop negotiation, zero-toolkit firewalls, and an interactive calculator landed; the Graphics raw-surface edge remains |
+| H0-H5 · Thin platform hosts | H0 complete; H1 in progress | Atomic frames, lifecycle recovery, stable-id raw input/reducers, long press, captured move, typed drag/drop negotiation and timed target activation, zero-toolkit firewalls, and an interactive calculator landed; the Graphics raw-surface edge remains |
 | T0-T5 · TSX native authoring | Proposed | Automatic JSX runtime, versioned Node-to-host session, state/event runtime, self-drawn native window, packages, and stable SDK |
 | M6-M8 · React Aria components | Catalog pinned; conformance planned | 51/51 families mapped; collection DnD authoring/behavior slice landed; eight public parts, full software, accessibility, and three-OS self-drawn evidence remain |
 

docs/architecture.md

@@ -478,7 +478,8 @@ move lifecycle, drag/drop lifecycle, collection action, change, focus, toggle,
 selection change, key down, and key up back to serialized action identifiers
 such as `onClick`, `onLongPress`, `onMoveStart`, `onMove`, `onMoveEnd`,
 `onDragStart`, `onDragMove`, `onDragEnd`, `onDropEnter`, `onDropMove`,
-`onDropExit`, `onDrop`, `onChange`, `onInput`, `onFocusChange`, `onAction`,
+`onDropActivate`, `onDropExit`, `onDrop`, `onChange`, `onInput`,
+`onFocusChange`, `onAction`,
 `onExpandedChange`, `onKeyDown`, and `onKeyUp`.
 Self-drawn drag callbacks carry a typed item array. Each text item preserves its
 complete format map; source events receive every item, while target events

docs/platform-hosts.md

@@ -215,6 +215,8 @@ src/platform_runtime/
 |- long_press_input.rs  event-loop deadlines and terminal hold recognition
 |- move_input.rs        captured incremental pointer and keyboard movement
 |- drag_drop.rs         typed transfer data and source/target negotiation
+|- drag_drop_activation_input.rs
+|                       800ms target hold deadline and activation routing
 |- drag_drop_input.rs   captured pointer drag lifecycle and target routing
 |- drag_drop_keyboard_input.rs
 |                       Enter/Tab/Escape accessible drag lifecycle
@@ -225,6 +227,8 @@ src/platform_runtime/
 |                       keyboard and style-only drag/drop gates
 |- drag_drop_items_tests.rs
 |                       multi-item/per-format transfer and filtering gates
+|- drag_drop_activation_tests.rs
+|                       pointer/keyboard/item timing and rollback gates
 |- presenter.rs         raw-surface prepare/publish contract and recorder
 |- reference_presenter.rs
 |                       transactional software Graphics evidence
@@ -395,11 +399,14 @@ Landed evidence:
   reducer errors preserve or roll back the entire session atomically. Collection
   targets additionally distinguish external insertion/root drops from internal
   move and same-parent reorder, reject self/descendant drops, and coalesce
-  adjacent insertion boundaries
+  adjacent insertion boundaries. Ordinary targets and collection items emit
+  `DropActivate` after an exact 800ms hold through the same host deadline;
+  collection roots do not activate, and target exit/change/cancel/drop clears
+  or restarts the timer
 - reducer errors restore the staged interaction state and sequence before the
   event is exposed as successful; successful frame reconciliation preserves
   focused stable ids, while rejected frames do not touch them
-- 59 focused runtime/software tests and four recursive feature/source
+- 63 focused runtime/software tests and four recursive feature/source
   firewall tests pass without any legacy renderer or OS toolkit dependency
 - `self_drawn_calculator` reproduces layout fingerprint
   `16529597026056060935`, scene fingerprint `2100550662756266801`, and

docs/react-aria-native.md

@@ -136,6 +136,12 @@ The first shared interaction milestone is available in the portable runtime:
   event-loop timer without exporting a toolkit timer into portable state.
   Deadline recognition and release-time fallback share the same ordering and
   reducer rollback, while pointer leave/re-entry cancels and restarts the hold.
+- The same portable deadline channel now implements React Aria's 800ms
+  `onDropActivate` hold. Moving inside one logical target refreshes event
+  context without postponing activation; changing targets restarts the timer,
+  while exit, drop, cancellation, and invalid keyed reconciliation clear it.
+  Pointer and keyboard drags share the lifecycle, and collection activation is
+  intentionally limited to item targets rather than `{type: root}`.
 - Self-drawn move routing starts on the first non-zero delta, keeps the
   initiating pointer captured outside its original hit region, preserves
   incremental position across keyed frames, and reference-counts concurrent
@@ -161,11 +167,12 @@ The first shared interaction milestone is available in the portable runtime:
   their source/target metadata and focusable keyboard affordances into that
   shared runtime. ListBox, GridList, Tree, and Table roots additionally lower
   `onRootDrop`, `onItemDrop`, `onInsert`, `onReorder`, `onMove`, and low-level
-  `onDrop` precedence; their items/rows and explicit DropIndicator parts use
-  the same self-drawn target model. Insert and root callbacks accept external
-  sessions, move accepts internal item/on-or-between targets, and reorder is
-  limited to internal same-parent boundaries. Valid combined callbacks retain
-  React Aria order, while low-level `onDrop` overrides high-level dispatch.
+  `onDrop` precedence plus `onDropActivate`; their items/rows and explicit
+  DropIndicator parts use the same self-drawn target model. Insert and root
+  callbacks accept external sessions, move accepts internal item/on-or-between
+  targets, and reorder is limited to internal same-parent boundaries. Valid
+  combined callbacks retain React Aria order, while low-level `onDrop`
+  overrides high-level dispatch.
   Selected descendants are removed when their selected ancestor is dragged,
   and internal self/descendant targets are rejected. Dynamic item acceptance
   and operation callbacks, external files/directories and cross-application

docs/roadmap.md

@@ -506,6 +506,12 @@ Landed evidence:
   custom exact types, and `all`; `DropEnter`/`DropMove`/`DropExit` ordering,
   `data-[dragging]`/`data-[drop-target]` state, keyed-frame reconciliation, and
   reducer failure rollback share the same transactional interaction session
+- valid ordinary targets and collection item targets schedule React Aria's
+  800ms `DropActivate` lifecycle through the same monotonic host deadline;
+  movement inside an equivalent target updates context without postponing the
+  timer, while target changes, exit, drop, cancellation, and invalid
+  reconciliation reset or clear it. Keyboard and pointer paths are identical,
+  and collection root targets intentionally do not activate
 - drag sources retain multiple text items and every per-item MIME/custom
   representation; target callbacks receive only matching items without losing
   the other representations on those items, while legacy `dragType` plus
@@ -523,7 +529,7 @@ Landed evidence:
 - the shared 410x620 calculator preserves its reviewed layout and scene
   fingerprints, routes eight fake-host events through four reducer actions,
   commits the resulting frames, and reaches display value `10`
-- 59 focused runtime/software tests plus four recursive H1 firewall tests are
+- 63 focused runtime/software tests plus four recursive H1 firewall tests are
   included in `just verify`
 
 Remaining H1 work:

docs/rsx.md

@@ -597,12 +597,16 @@ Target callbacks receive only matching items, with every representation on
 those items preserved. `UiDraggable`, `UiDroppable`, and `UiDropZone` include a
 keyboard-focusable affordance: Enter starts or commits a drag, Tab cycles
 compatible targets, and Escape cancels. Pointer and keyboard callbacks receive
-the same typed transfer context.
+the same typed transfer context. `UiDroppable` and `UiDropZone` accept
+`onDropActivate`; a valid target held for 800ms emits it once, movement inside
+that target keeps the original deadline, and exit, drop, cancellation, or a
+target change clears or restarts it.
 
 `UiListBox`, `UiGridList`, `UiTree`, and `UiTable` also expose the shared
 collection contract. Their roots accept `onRootDrop`, `onItemDrop`, `onInsert`,
-`onReorder`, `onMove`, the low-level overriding `onDrop`, lifecycle handlers,
-`acceptedDragTypes`, `dropOperation`, `allowedDropOperations`, and
+`onReorder`, `onMove`, the low-level overriding `onDrop`, lifecycle handlers
+including `onDropActivate`, `acceptedDragTypes`, `dropOperation`,
+`allowedDropOperations`, and
 `dropOrientation`. Collection `onMove` lowers to a dedicated native event so
 it does not collide with the generic move-gesture callback. Item/row components
 accept a stable `id` plus `isDraggable`, `dragType`, `dragValue`, and
@@ -621,7 +625,9 @@ external collection sessions; internal `onMove` accepts item/on-or-between
 targets, while `onReorder` accepts same-parent boundaries. `onItemDrop` plus
 `onMove`, or `onMove` plus `onReorder`, may both run in React Aria order;
 low-level `onDrop` replaces this routing. Self and descendant targets are
-rejected, and adjacent `after`/`before` boundaries are equivalent. Dynamic
+rejected, and adjacent `after`/`before` boundaries are equivalent.
+`onDropActivate` runs only for collection item descriptors, never the root
+descriptor. Dynamic
 acceptance/operation callbacks, external OS files/directories,
 cross-application transfer, drag previews, and final accessibility/host
 conformance remain separate work.

docs/tsx-native-runtime.md

@@ -289,6 +289,16 @@ The action registry retains callbacks for the active committed revision and
 one rollback revision. A commit atomically replaces the active action scope.
 Late events for an older revision are rejected before callback dispatch.
 
+Callbacks that decide hit testing before an event is dispatched are a distinct
+protocol concern. In particular, React Aria's `shouldAcceptItemDrop` and
+`getDropOperation` require a synchronous answer while resolving the current
+collection target. They must not be encoded as ordinary action ids, serialized
+closures, or post-event reducers. Before these APIs are exposed to TSX, the
+session protocol must define a revision-scoped policy decision/query contract
+with bounded execution, stale-revision rejection, and `cancel` as the safe
+timeout/failure result (or an equivalent declarative decision table). Node
+continues to own JavaScript callbacks; the Rust host never executes JS.
+
 ### Components and Hooks
 
 The initial runtime is intentionally smaller than React:

src/compiler.rs

@@ -2563,6 +2563,7 @@ fn drop_zone_scope_value(props: &CompiledProps) -> GuiResult<JsonValue> {
             .on_drag_leave(non_empty_prop_action(props.events.get("onDragLeave")))
             .on_drop_enter(non_empty_prop_action(props.events.get("onDropEnter")))
             .on_drop_move(non_empty_prop_action(props.events.get("onDropMove")))
+            .on_drop_activate(non_empty_prop_action(props.events.get("onDropActivate")))
             .on_drop_exit(non_empty_prop_action(props.events.get("onDropExit")))
             .accepted_drag_types(non_empty_attribute(
                 props,
@@ -2615,6 +2616,7 @@ fn drop_scope_value(props: &CompiledProps) -> GuiResult<JsonValue> {
             .on_drop_enter(non_empty_prop_action(props.events.get("onDropEnter")))
             .on_drop_exit(non_empty_prop_action(props.events.get("onDropExit")))
             .on_drop_move(non_empty_prop_action(props.events.get("onDropMove")))
+            .on_drop_activate(non_empty_prop_action(props.events.get("onDropActivate")))
             .accepted_drag_types(non_empty_attribute(
                 props,
                 &["acceptedDragTypes", "data-accepted-drag-types"],

src/event.rs

@@ -69,6 +69,7 @@ pub enum NativeEventKind {
     DragEnd,
     DropEnter,
     DropMove,
+    DropActivate,
     DropExit,
     Drop,
     Action,
@@ -209,6 +210,7 @@ impl NativeEvent {
             | NativeEventKind::DragEnd
             | NativeEventKind::DropEnter
             | NativeEventKind::DropMove
+            | NativeEventKind::DropActivate
             | NativeEventKind::DropExit
             | NativeEventKind::Drop
             | NativeEventKind::Wheel => NativeInputModality::Mouse,

src/interaction.rs

@@ -489,7 +489,9 @@ impl InteractionState {
             NativeEventKind::DragEnd => {
                 after.dragging = false;
             }
-            NativeEventKind::DropEnter | NativeEventKind::DropMove => {
+            NativeEventKind::DropEnter
+            | NativeEventKind::DropMove
+            | NativeEventKind::DropActivate => {
                 after.drop_target = true;
             }
             NativeEventKind::DropExit | NativeEventKind::Drop => {
@@ -574,6 +576,7 @@ impl InteractionState {
                     | NativeEventKind::DragEnd
                     | NativeEventKind::DropEnter
                     | NativeEventKind::DropMove
+                    | NativeEventKind::DropActivate
                     | NativeEventKind::DropExit
                     | NativeEventKind::Drop
                     | NativeEventKind::Focus