diff --git a/apps/client/src/features/base/hooks/__tests__/resolve-card-drop.spec.ts b/apps/client/src/features/base/hooks/__tests__/resolve-card-drop.spec.ts
new file mode 100644
index 000000000..f93fee353
--- /dev/null
+++ b/apps/client/src/features/base/hooks/__tests__/resolve-card-drop.spec.ts
@@ -0,0 +1,108 @@
+import { describe, it, expect, vi } from "vitest";
+
+vi.mock("fractional-indexing-jittered", () => ({
+  generateJitteredKeyBetween: (a: string | null, b: string | null) =>
+    `${a ?? "START"}|${b ?? "END"}`,
+}));
+
+import { resolveCardDrop } from "../resolve-card-drop";
+import { NO_VALUE_CHOICE_ID } from "@/features/base/types/base.types";
+
+const mkRow = (id: string, position: string) =>
+  ({ id, position, cells: {} }) as any;
+
+describe("resolveCardDrop", () => {
+  it("returns cells-only when cross-column drop happens with sort active", () => {
+    const result = resolveCardDrop({
+      draggedCardId: "r1",
+      targetCardId: "r2",
+      edge: "top",
+      sourceColumnKey: "c1",
+      targetColumnKey: "c2",
+      groupByPropertyId: "prop-status",
+      columnRows: [mkRow("r2", "b")],
+      sortsActive: true,
+    });
+    expect(result.cells).toEqual({ "prop-status": "c2" });
+    expect(result.position).toBeUndefined();
+  });
+
+  it("writes null cell value when target is the NO_VALUE column", () => {
+    const result = resolveCardDrop({
+      draggedCardId: "r1",
+      targetCardId: "r2",
+      edge: "top",
+      sourceColumnKey: "c1",
+      targetColumnKey: NO_VALUE_CHOICE_ID,
+      groupByPropertyId: "prop-status",
+      columnRows: [mkRow("r2", "b")],
+      sortsActive: false,
+    });
+    expect(result.cells).toEqual({ "prop-status": null });
+  });
+
+  it("returns position-only when intra-column drop with no sort", () => {
+    const result = resolveCardDrop({
+      draggedCardId: "r1",
+      targetCardId: "r2",
+      edge: "bottom",
+      sourceColumnKey: "c1",
+      targetColumnKey: "c1",
+      groupByPropertyId: "prop-status",
+      columnRows: [mkRow("r2", "a"), mkRow("r3", "c")],
+      sortsActive: false,
+    });
+    expect(result.cells).toBeUndefined();
+    expect(typeof result.position).toBe("string");
+    // Between 'a' (r2) and 'c' (r3) → some key, exact value depends on jitter
+    // but must satisfy 'a' < key < 'c' for typical jitter outputs.
+    expect(result.position! > "a").toBe(true);
+    expect(result.position! < "c").toBe(true);
+  });
+
+  it("returns both cells and position for cross-column with slot", () => {
+    const result = resolveCardDrop({
+      draggedCardId: "r1",
+      targetCardId: "r2",
+      edge: "top",
+      sourceColumnKey: "c1",
+      targetColumnKey: "c2",
+      groupByPropertyId: "prop-status",
+      columnRows: [mkRow("r2", "b"), mkRow("r3", "d")],
+      sortsActive: false,
+    });
+    expect(result.cells).toEqual({ "prop-status": "c2" });
+    expect(typeof result.position).toBe("string");
+    expect(result.position! < "b").toBe(true);
+  });
+
+  it("appends to the end when targetCardId is not in columnRows (empty/below-last)", () => {
+    const result = resolveCardDrop({
+      draggedCardId: "r1",
+      targetCardId: "__column-body__", // sentinel
+      edge: "bottom",
+      sourceColumnKey: "c1",
+      targetColumnKey: "c2",
+      groupByPropertyId: "prop-status",
+      columnRows: [mkRow("r5", "z")],
+      sortsActive: false,
+    });
+    expect(result.cells).toEqual({ "prop-status": "c2" });
+    expect(result.position! > "z").toBe(true);
+  });
+
+  it("returns undefined for both fields when same column and sort active", () => {
+    const result = resolveCardDrop({
+      draggedCardId: "r1",
+      targetCardId: "r2",
+      edge: "top",
+      sourceColumnKey: "c1",
+      targetColumnKey: "c1",
+      groupByPropertyId: "prop-status",
+      columnRows: [mkRow("r2", "a")],
+      sortsActive: true,
+    });
+    expect(result.cells).toBeUndefined();
+    expect(result.position).toBeUndefined();
+  });
+});
diff --git a/apps/client/src/features/base/hooks/resolve-card-drop.ts b/apps/client/src/features/base/hooks/resolve-card-drop.ts
new file mode 100644
index 000000000..7ea53531a
--- /dev/null
+++ b/apps/client/src/features/base/hooks/resolve-card-drop.ts
@@ -0,0 +1,88 @@
+import { generateJitteredKeyBetween } from "fractional-indexing-jittered";
+import { IBaseRow, NO_VALUE_CHOICE_ID } from "@/features/base/types/base.types";
+
+type Edge = "top" | "bottom";
+
+export type ResolveCardDropInput = {
+  draggedCardId: string;
+  targetCardId: string;
+  edge: Edge | null;
+  sourceColumnKey: string;
+  targetColumnKey: string;
+  groupByPropertyId: string;
+  columnRows: IBaseRow[]; // rows currently in the target column, in display order
+  sortsActive: boolean;
+};
+
+export type ResolveCardDropResult = {
+  cells: Record<string, unknown> | undefined;
+  position: string | undefined;
+};
+
+export function resolveCardDrop(
+  input: ResolveCardDropInput,
+): ResolveCardDropResult {
+  const {
+    draggedCardId,
+    targetCardId,
+    edge,
+    sourceColumnKey,
+    targetColumnKey,
+    groupByPropertyId,
+    columnRows,
+    sortsActive,
+  } = input;
+
+  const sameColumn = sourceColumnKey === targetColumnKey;
+
+  // Compute the cells patch first.
+  const cells = sameColumn
+    ? undefined
+    : {
+        [groupByPropertyId]:
+          targetColumnKey === NO_VALUE_CHOICE_ID ? null : targetColumnKey,
+      };
+
+  // Same column + sort active → block (caller should have stopped the drag
+  // via canDrop, but we return no-op for safety).
+  if (sameColumn && sortsActive) {
+    return { cells: undefined, position: undefined };
+  }
+
+  // Sort active and cross-column → only cells, no position.
+  if (sortsActive) {
+    return { cells, position: undefined };
+  }
+
+  // Sort inactive → compute the slot.
+  // Filter the dragged card out of the column (it may already be there
+  // when intra-column drag).
+  const target = columnRows.filter((r) => r.id !== draggedCardId);
+  const targetIndex = target.findIndex((r) => r.id === targetCardId);
+
+  let lower: string | null;
+  let upper: string | null;
+
+  if (targetIndex === -1) {
+    // Drop on column body / sentinel / below-last → append.
+    const last = target[target.length - 1];
+    lower = last?.position ?? null;
+    upper = null;
+  } else if (edge === "top") {
+    lower = target[targetIndex - 1]?.position ?? null;
+    upper = target[targetIndex].position;
+  } else {
+    lower = target[targetIndex].position;
+    upper = target[targetIndex + 1]?.position ?? null;
+  }
+
+  let position: string;
+  try {
+    position = generateJitteredKeyBetween(lower, upper);
+  } catch {
+    // Identical keys (rare; happens when two rows briefly share a position
+    // during a concurrent edit). Fall back to insert-after-lower.
+    position = generateJitteredKeyBetween(lower, null);
+  }
+  return { cells, position };
+}