always set lane

apps/web/src/functions/create-timeline-item.ts

@@ -1,8 +1,10 @@
 import { db } from "@zendegi/db";
 import { timelineItem } from "@zendegi/db/schema/timeline";
+import { eq } from "drizzle-orm";
 import { createServerFn } from "@tanstack/react-start";
 import { z } from "zod";
 import { authMiddleware } from "@/middleware/auth";
+import { assignLane } from "@/lib/assign-lane";
 
 export const createTimelineItem = createServerFn({ method: "POST" })
   .middleware([authMiddleware])
@@ -19,6 +21,12 @@ export const createTimelineItem = createServerFn({ method: "POST" })
     })
   )
   .handler(async ({ data }) => {
+    const existing = await db.query.timelineItem.findMany({
+      where: eq(timelineItem.timelineGroupId, data.timelineGroupId),
+    });
+
+    const lane = assignLane(existing, data.start, data.end ?? null);
+
     const [newItem] = await db
       .insert(timelineItem)
       .values({
@@ -27,6 +35,7 @@ export const createTimelineItem = createServerFn({ method: "POST" })
         start: data.start,
         end: data.end,
         timelineGroupId: data.timelineGroupId,
+        lane,
       })
       .returning();
 

apps/web/src/functions/update-timeline-item.ts

@@ -0,0 +1,35 @@
+import { db } from "@zendegi/db";
+import { timelineItem } from "@zendegi/db/schema/timeline";
+import { eq } from "drizzle-orm";
+import { createServerFn } from "@tanstack/react-start";
+import { z } from "zod";
+import { authMiddleware } from "@/middleware/auth";
+
+export const updateTimelineItem = createServerFn({ method: "POST" })
+  .middleware([authMiddleware])
+  .inputValidator(
+    z.object({
+      id: z.string().uuid(),
+      start: z.string().transform((s) => new Date(s)),
+      end: z
+        .string()
+        .nullable()
+        .transform((s) => (s ? new Date(s) : null)),
+      timelineGroupId: z.string().uuid(),
+      lane: z.number().int().min(1),
+    })
+  )
+  .handler(async ({ data }) => {
+    const [updated] = await db
+      .update(timelineItem)
+      .set({
+        start: data.start,
+        end: data.end,
+        timelineGroupId: data.timelineGroupId,
+        lane: data.lane,
+      })
+      .where(eq(timelineItem.id, data.id))
+      .returning();
+
+    return updated;
+  });

apps/web/src/lib/assign-lane.ts

@@ -0,0 +1,26 @@
+/**
+ * Greedy lane assignment: finds the first lane (1-100) where the new item
+ * does not overlap any existing item in the same group.
+ *
+ * Port of the Flutter `_assignLane` algorithm so the server can compute
+ * lanes on item creation.
+ */
+export function assignLane(
+  existingItems: { start: Date; end: Date | null; lane: number }[],
+  newStart: Date,
+  newEnd: Date | null
+): number {
+  const end = newEnd ?? new Date(newStart.getTime() + 24 * 60 * 60 * 1000); // default 1 day
+
+  for (let lane = 1; lane <= 100; lane++) {
+    const hasConflict = existingItems.some((item) => {
+      if (item.lane !== lane) return false;
+      const itemEnd =
+        item.end ?? new Date(item.start.getTime() + 24 * 60 * 60 * 1000);
+      // Overlaps if: newStart < itemEnd && newEnd > itemStart
+      return newStart < itemEnd && end > item.start;
+    });
+    if (!hasConflict) return lane;
+  }
+  return 1;
+}

apps/web/src/routes/api/mcp/$.ts

@@ -11,6 +11,7 @@ import {
 } from "@zendegi/db/schema/timeline";
 import { and, eq } from "drizzle-orm";
 import { z } from "zod";
+import { assignLane } from "@/lib/assign-lane";
 
 function createMcpServer(userId: string) {
   const server = new McpServer({
@@ -141,14 +142,23 @@ function createMcpServer(userId: string) {
           isError: true,
         };
       }
+
+      const existing = await db.query.timelineItem.findMany({
+        where: eq(timelineItem.timelineGroupId, timelineGroupId),
+      });
+      const newStart = new Date(start);
+      const newEnd = end ? new Date(end) : null;
+      const lane = assignLane(existing, newStart, newEnd);
+
       const [created] = await db
         .insert(timelineItem)
         .values({
           title,
           description,
-          start: new Date(start),
-          end: end ? new Date(end) : undefined,
+          start: newStart,
+          end: newEnd ?? undefined,
           timelineGroupId,
+          lane,
         })
         .returning();
       return {
@@ -173,9 +183,10 @@ function createMcpServer(userId: string) {
           .nullable()
           .optional()
           .describe("New end date (ISO 8601, or null to remove)"),
+        lane: z.number().int().min(1).optional().describe("Lane number"),
       },
     },
-    async ({ id, title, description, start, end }) => {
+    async ({ id, title, description, start, end, lane }) => {
       // Verify ownership through item → group → timeline
       const item = await db.query.timelineItem.findFirst({
         where: eq(timelineItem.id, id),
@@ -193,6 +204,7 @@ function createMcpServer(userId: string) {
       if (description !== undefined) updates.description = description;
       if (start !== undefined) updates.start = new Date(start);
       if (end !== undefined) updates.end = end ? new Date(end) : null;
+      if (lane !== undefined) updates.lane = lane;
 
       const [updated] = await db
         .update(timelineItem)

apps/web/src/routes/timeline.$timelineId.tsx

@@ -1,7 +1,8 @@
 import { useCallback, useMemo, useState } from "react";
 import { createFileRoute } from "@tanstack/react-router";
-import { useSuspenseQuery } from "@tanstack/react-query";
+import { useSuspenseQuery, useQueryClient } from "@tanstack/react-query";
 import { timelineQueryOptions } from "@/functions/get-timeline";
+import { updateTimelineItem } from "@/functions/update-timeline-item";
 import { FlutterView } from "@/components/flutter-view";
 
 export const Route = createFileRoute("/timeline/$timelineId")({
@@ -17,6 +18,7 @@ function RouteComponent() {
   const { timelineId } = Route.useParams();
   const timelineQuery = useSuspenseQuery(timelineQueryOptions(timelineId));
   const timeline = timelineQuery.data;
+  const queryClient = useQueryClient();
   const [selectedItemId, setSelectedItemId] = useState<string | null>(null);
 
   const flutterState = useMemo(
@@ -34,6 +36,7 @@ function RouteComponent() {
             description: item.description,
             start: item.start,
             end: item.end,
+            lane: item.lane,
           })),
         })),
       },
@@ -56,9 +59,75 @@ function RouteComponent() {
         case "item_deselected":
           setSelectedItemId(null);
           break;
+        case "entry_moved": {
+          const p = event.payload;
+          if (!p) break;
+          const entryId = p.entryId as string;
+          const newStart = p.newStart as string;
+          const newEnd = p.newEnd as string;
+          const newGroupId = p.newGroupId as string;
+          const newLane = p.newLane as number;
+
+          // Optimistic cache update
+          queryClient.setQueryData(
+            ["timeline", timelineId],
+            (old: typeof timeline | undefined) => {
+              if (!old) return old;
+              let movedItem:
+                | (typeof old.groups)[number]["items"][number]
+                | undefined;
+
+              const groups = old.groups.map((group) => {
+                const filtered = group.items.filter((item) => {
+                  if (item.id === entryId) {
+                    movedItem = item;
+                    return false;
+                  }
+                  return true;
+                });
+                return { ...group, items: filtered };
+              });
+
+              if (!movedItem) return old;
+
+              return {
+                ...old,
+                groups: groups.map((group) =>
+                  group.id === newGroupId
+                    ? {
+                        ...group,
+                        items: [
+                          ...group.items,
+                          {
+                            ...movedItem!,
+                            start: newStart,
+                            end: newEnd,
+                            lane: newLane,
+                            timelineGroupId: newGroupId,
+                          },
+                        ],
+                      }
+                    : group
+                ),
+              };
+            }
+          );
+
+          // Persist to DB
+          updateTimelineItem({
+            data: {
+              id: entryId,
+              start: newStart,
+              end: newEnd,
+              timelineGroupId: newGroupId,
+              lane: newLane,
+            },
+          });
+          break;
+        }
       }
     },
-    []
+    [queryClient, timelineId]
   );
 
   return (