Govern task context and advance execution pointer

web/protocol/input-modal.ts

@@ -11,6 +11,12 @@ export interface InputModalState {
   mainCommitCount: number;
 }
 
+export interface InputModalEvent {
+  type: "pointerdown" | "pointerup" | "pointercancel";
+  pointerType: "touch" | "pen";
+  pointerId: number;
+}
+
 export function createInputModalState(): InputModalState {
   return { schemaVersion: 1, kind: "NONE", activePointerIds: [], cancelled: false, navigationRevision: 0, mainCommitCount: 0 };
 }
@@ -39,3 +45,15 @@ export function commitPenStroke(state: InputModalState, pointerId: number): Inpu
   if (state.kind !== "PEN_STROKE" || !state.activePointerIds.includes(pointerId) || state.cancelled) return state;
   return { ...state, kind: "NONE", activePointerIds: [], mainCommitCount: state.mainCommitCount + 1 };
 }
+
+export function reduceInputModal(state: InputModalState, event: InputModalEvent): InputModalState {
+  if (!Number.isSafeInteger(event.pointerId) || event.pointerId < 0) throw new Error("POINTER_ID_INVALID");
+  if (event.pointerType === "touch") {
+    if (event.type === "pointerdown") return beginTouch(state, event.pointerId);
+    if (event.type === "pointerup") return endTouch(state, event.pointerId);
+    return cancelInputModal(state);
+  }
+  if (event.type === "pointerdown") return beginPenStroke(state, event.pointerId);
+  if (event.type === "pointerup") return commitPenStroke(state, event.pointerId);
+  return cancelInputModal(state);
+}