refactor(web): extract range selection bootstrap

apps/web/src/hooks/timelineRangeSelection.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from "vitest";
-import { finalizeRangeSelection, updateRangeSelectionDraft } from "./timelineRangeSelection.js";
+import { createRangeSelectionState, finalizeRangeSelection, updateRangeSelectionDraft } from "./timelineRangeSelection.js";
 
 type TestRangeState = {
   isSelecting: boolean;
@@ -11,6 +11,23 @@ type TestRangeState = {
 };
 
 describe("timelineRangeSelection", () => {
+  it("creates a selection draft with currentDate anchored to the start date", () => {
+    expect(
+      createRangeSelectionState<TestRangeState>(
+        "res-1",
+        new Date("2025-01-15T12:00:00.000Z"),
+        100,
+      ),
+    ).toEqual({
+      isSelecting: true,
+      resourceId: "res-1",
+      startDate: new Date("2025-01-15T12:00:00.000Z"),
+      currentDate: new Date("2025-01-15T12:00:00.000Z"),
+      suggestedProjectId: null,
+      startClientX: 100,
+    });
+  });
+
   it("ignores updates when no full day boundary was crossed", () => {
     const state: TestRangeState = {
       isSelecting: true,

apps/web/src/hooks/timelineRangeSelection.ts

@@ -18,6 +18,22 @@ export type RangeSelectionResult = {
   anchorY: number;
 };
 
+export function createRangeSelectionState<TState extends RangeStateLike>(
+  resourceId: string,
+  startDate: Date,
+  startClientX: number,
+  suggestedProjectId?: string | null,
+): TState {
+  return {
+    isSelecting: true,
+    resourceId,
+    startDate,
+    currentDate: startDate,
+    suggestedProjectId: suggestedProjectId ?? null,
+    startClientX,
+  } as TState;
+}
+
 export function updateRangeSelectionDraft<TState extends RangeStateLike>(
   state: TState,
   currentClientX: number,

apps/web/src/hooks/useTimelineDrag.ts

@@ -31,7 +31,7 @@ import {
   updateMultiSelectDraft,
 } from "./timelineMultiSelect.js";
 import { reconcileOptimisticEntries } from "./timelineOptimisticAllocations.js";
-import { finalizeRangeSelection, updateRangeSelectionDraft } from "./timelineRangeSelection.js";
+import { createRangeSelectionState, finalizeRangeSelection, updateRangeSelectionDraft } from "./timelineRangeSelection.js";
 import { getTouchPoint, resolveTouchDragDecision } from "./timelineTouch.js";
 
 const DRAG_CLICK_THRESHOLD_PX = 5;
@@ -826,14 +826,12 @@ export function useTimelineDrag({
       if (dragStateRef.current.isDragging || allocDragRef.current.isActive) return;
       if (e.button !== 0) return;
       e.preventDefault();
-      const state: RangeState = {
-        isSelecting: true,
-        resourceId: opts.resourceId,
-        startDate: opts.startDate,
-        currentDate: opts.startDate,
-        suggestedProjectId: opts.suggestedProjectId ?? null,
-        startClientX: e.clientX,
-      };
+      const state = createRangeSelectionState<RangeState>(
+        opts.resourceId,
+        opts.startDate,
+        e.clientX,
+        opts.suggestedProjectId,
+      );
       rangeStateRef.current = state;
       setRangeState(state);
     },

scripts/check-architecture-guardrails.mjs

@@ -153,6 +153,10 @@ export const rules = [
     file: "apps/web/src/hooks/timelineRangeSelection.ts",
     maxLines: 90,
     required: [
+      {
+        pattern: /\bexport function createRangeSelectionState\b/,
+        message: "timeline range helpers must keep selection bootstrap centralized",
+      },
       {
         pattern: /\bexport function updateRangeSelectionDraft\b/,
         message: "timeline range helpers must keep preview date derivation centralized",
@@ -304,7 +308,7 @@ export const rules = [
     ],
     forbidden: [
       {
-        pattern: /\bfunction (?:toPxValue|joinTransforms|captureLivePreviewTargets|renderLivePreview|scheduleLivePreview|clearLivePreview|datesMatch|preserveLivePreview)\b/,
+        pattern: /\bfunction (?:toPxValue|joinTransforms|captureLivePreviewTargets|renderLivePreview|scheduleLivePreview|clearLivePreview|datesMatch|preserveLivePreview|createRangeSelectionState)\b/,
         message: "timeline drag must not re-inline live preview helper implementations",
       },
       {

scripts/check-architecture-guardrails.test.mjs

@@ -121,6 +121,7 @@ describe("architecture guardrails", () => {
     ]);
 
     assert.deepEqual(evaluateRule(rangeRule, "export function updateRangeSelectionDraft() {}\n"), [
+      "apps/web/src/hooks/timelineRangeSelection.ts: missing guardrail anchor: timeline range helpers must keep selection bootstrap centralized",
       "apps/web/src/hooks/timelineRangeSelection.ts: missing guardrail anchor: timeline range helpers must keep ordered range finalization centralized",
     ]);