refactor(web): extract project drag session

scripts/check-architecture-guardrails.mjs

@@ -329,6 +329,17 @@ export const rules = [
     ],
     forbidden: [],
   },
+  {
+    file: "apps/web/src/hooks/timelineProjectDragSession.ts",
+    maxLines: 70,
+    required: [
+      {
+        pattern: /\bexport function beginProjectDragSession\b/,
+        message: "timeline project drag session helpers must keep document drag lifecycle centralized",
+      },
+    ],
+    forbidden: [],
+  },
   {
     file: "apps/web/src/hooks/useTimelineDrag.ts",
     required: [
@@ -388,6 +399,10 @@ export const rules = [
         pattern: /from "\.\/timelineProjectDrag\.js"/,
         message: "timeline drag must keep project drag bootstrap and mutation gating delegated to the extracted helper module",
       },
+      {
+        pattern: /from "\.\/timelineProjectDragSession\.js"/,
+        message: "timeline drag must keep project drag document session wiring delegated to the extracted helper module",
+      },
     ],
     forbidden: [
       {

scripts/check-architecture-guardrails.test.mjs

@@ -85,6 +85,7 @@ describe("architecture guardrails", () => {
     const documentDragRule = rules.find((rule) => rule.file === "apps/web/src/hooks/timelineDocumentDrag.ts");
     const allocationDragStateRule = rules.find((rule) => rule.file === "apps/web/src/hooks/timelineAllocationDragState.ts");
     const projectDragRule = rules.find((rule) => rule.file === "apps/web/src/hooks/timelineProjectDrag.ts");
+    const projectDragSessionRule = rules.find((rule) => rule.file === "apps/web/src/hooks/timelineProjectDragSession.ts");
 
     assert.ok(dragRule);
     assert.ok(livePreviewRule);
@@ -102,6 +103,7 @@ describe("architecture guardrails", () => {
     assert.ok(documentDragRule);
     assert.ok(allocationDragStateRule);
     assert.ok(projectDragRule);
+    assert.ok(projectDragSessionRule);
 
     assert.deepEqual(evaluateRule(dragRule, "function clearLivePreview() {}\n"), [
       "apps/web/src/hooks/useTimelineDrag.ts: missing guardrail anchor: timeline drag must keep live preview behavior delegated to the extracted helper module",
@@ -118,6 +120,7 @@ describe("architecture guardrails", () => {
       "apps/web/src/hooks/useTimelineDrag.ts: missing guardrail anchor: timeline drag must keep allocation multi-drag rules delegated to the extracted helper module",
       "apps/web/src/hooks/useTimelineDrag.ts: missing guardrail anchor: timeline drag must keep allocation drag bootstrap delegated to the extracted helper module",
       "apps/web/src/hooks/useTimelineDrag.ts: missing guardrail anchor: timeline drag must keep project drag bootstrap and mutation gating delegated to the extracted helper module",
+      "apps/web/src/hooks/useTimelineDrag.ts: missing guardrail anchor: timeline drag must keep project drag document session wiring delegated to the extracted helper module",
       "apps/web/src/hooks/useTimelineDrag.ts: forbidden pattern matched: timeline drag must not re-inline live preview helper implementations",
     ]);
 
@@ -189,6 +192,10 @@ describe("architecture guardrails", () => {
       "apps/web/src/hooks/timelineProjectDrag.ts: missing guardrail anchor: timeline project drag helpers must keep no-op project-shift mutation gating centralized",
     ]);
 
+    assert.deepEqual(evaluateRule(projectDragSessionRule, ""), [
+      "apps/web/src/hooks/timelineProjectDragSession.ts: missing guardrail anchor: timeline project drag session helpers must keep document drag lifecycle centralized",
+    ]);
+
     assert.deepEqual(
       evaluateRule(
         dragRule,
@@ -208,6 +215,7 @@ describe("architecture guardrails", () => {
         "apps/web/src/hooks/useTimelineDrag.ts: missing guardrail anchor: timeline drag must keep allocation multi-drag rules delegated to the extracted helper module",
         "apps/web/src/hooks/useTimelineDrag.ts: missing guardrail anchor: timeline drag must keep allocation drag bootstrap delegated to the extracted helper module",
         "apps/web/src/hooks/useTimelineDrag.ts: missing guardrail anchor: timeline drag must keep project drag bootstrap and mutation gating delegated to the extracted helper module",
+        "apps/web/src/hooks/useTimelineDrag.ts: missing guardrail anchor: timeline drag must keep project drag document session wiring delegated to the extracted helper module",
         "apps/web/src/hooks/useTimelineDrag.ts: forbidden pattern matched: timeline drag must not re-inline synthetic touch pointer adapters",
       ],
     );