diff --git a/src/app/(protected)/workorders/_components/list/duplicate-wo-number-dialog.tsx b/src/app/(protected)/workorders/_components/list/duplicate-wo-number-dialog.tsx
new file mode 100644
index 00000000..95decbe7
--- /dev/null
+++ b/src/app/(protected)/workorders/_components/list/duplicate-wo-number-dialog.tsx
@@ -0,0 +1,45 @@
+import { Button, Dialog, DialogActions, DialogContent, DialogTitle } from "@mui/material";
+import { Text } from "@/components/ui/text";
+import type { WorkOrderTableRow } from "@/domain/work-orders/types/work-order-table-row";
+
+type DuplicateWoNumberDialogProps = {
+  open: boolean;
+  existing: WorkOrderTableRow | null;
+  onDismiss: () => void;
+  onViewExisting: (row: WorkOrderTableRow) => void;
+};
+
+export function DuplicateWoNumberDialog({
+  open,
+  existing,
+  onDismiss,
+  onViewExisting,
+}: DuplicateWoNumberDialogProps) {
+  const woNumber = existing?.woNumber ?? "";
+
+  return (
+    <Dialog open={open} onClose={onDismiss} aria-labelledby="duplicate-wo-number-dialog-title">
+      <DialogTitle id="duplicate-wo-number-dialog-title">Duplicate Work Order Number</DialogTitle>
+      <DialogContent>
+        <Text variant="body">
+          Work order number {woNumber} is already assigned to another work order. View the existing
+          record or dismiss to keep editing.
+        </Text>
+      </DialogContent>
+      <DialogActions>
+        <Button onClick={onDismiss}>Dismiss</Button>
+        <Button
+          variant="contained"
+          disabled={existing == null}
+          onClick={() => {
+            if (existing != null) {
+              onViewExisting(existing);
+            }
+          }}
+        >
+          View existing
+        </Button>
+      </DialogActions>
+    </Dialog>
+  );
+}
diff --git a/src/app/(protected)/workorders/_components/list/table/use-wo-table-row-handlers.ts b/src/app/(protected)/workorders/_components/list/table/use-wo-table-row-handlers.ts
index 59aca8f5..c9626b3e 100644
--- a/src/app/(protected)/workorders/_components/list/table/use-wo-table-row-handlers.ts
+++ b/src/app/(protected)/workorders/_components/list/table/use-wo-table-row-handlers.ts
@@ -19,6 +19,7 @@ type UseWoTableRowHandlersOptions = {
   onOpenMedia: (row: WorkOrderTableRow) => void;
   onPatch: (id: string | number, patch: WorkOrderTablePatch) => void;
   onScheduleHighlight: (id: string | number | null) => void;
+  onDuplicateFound?: (existing: WorkOrderTableRow) => void;
 };
 
 export function useWoTableRowHandlers({
@@ -30,6 +31,7 @@ export function useWoTableRowHandlers({
   onOpenMedia,
   onPatch,
   onScheduleHighlight,
+  onDuplicateFound,
 }: UseWoTableRowHandlersOptions): WoTableRowHandlers {
   const {
     dragState: dragStateRef,
@@ -97,8 +99,7 @@ export function useWoTableRowHandlers({
         });
       },
       onDuplicateFound: (existing: WorkOrderTableRow) => {
-        tableData.setSelectedId(existing.id);
-        onOpenSlideOver(existing, false);
+        onDuplicateFound?.(existing);
       },
       onOpenSlideOver: (row: WorkOrderTableRow) => onOpenSlideOver(row, false),
       onPastDueAttempt: (id: string | number) => onScheduleHighlight(id),
@@ -138,6 +139,7 @@ export function useWoTableRowHandlers({
       onOpenMedia,
       onPatch,
       onScheduleHighlight,
+      onDuplicateFound,
     ],
   );
 }
diff --git a/src/app/(protected)/workorders/_components/list/table/wo-table.tsx b/src/app/(protected)/workorders/_components/list/table/wo-table.tsx
index e94c3ad7..cb5b8a9f 100644
--- a/src/app/(protected)/workorders/_components/list/table/wo-table.tsx
+++ b/src/app/(protected)/workorders/_components/list/table/wo-table.tsx
@@ -10,6 +10,7 @@ import type {
   WorkOrderTableRow,
 } from "@/domain/work-orders/types/work-order-table-row";
 import { useCreateWorkOrderFromWizard } from "@/domain/work-orders/use-cases/use-create-work-order-from-wizard";
+import { DuplicateWoNumberDialog } from "@/app/(protected)/workorders/_components/list/duplicate-wo-number-dialog";
 import { WoTableSkeleton } from "@/app/(protected)/workorders/_components/loading/wo-table-skeleton";
 import type { ReturnTypeOfUseWorkOrdersTableData } from "./wo-table-types";
 import { buildInlineDraftCreateInput } from "./build-inline-draft-create-input";
@@ -55,6 +56,7 @@ export function WoTable({
   onPatch,
 }: WoTableProps) {
   const [scheduleHighlightId, setScheduleHighlightId] = useState<string | number | null>(null);
+  const [duplicateRow, setDuplicateRow] = useState<WorkOrderTableRow | null>(null);
   const { data: locationSites = [] } = useLocationSites();
   const sitePlaceLookups = useMemo(() => buildSitePlaceLookups(locationSites), [locationSites]);
   const createMutation = useCreateWorkOrderFromWizard(() => {
@@ -70,6 +72,7 @@ export function WoTable({
     onOpenMedia,
     onPatch,
     onScheduleHighlight: setScheduleHighlightId,
+    onDuplicateFound: setDuplicateRow,
   });
 
   const renderRow = (row: WorkOrderTableRow, forceScheduleHighlight = false) => (
@@ -150,21 +153,33 @@ export function WoTable({
   }
 
   return (
-    <WoTableShell>
-      <table
-        style={{
-          width: "100%",
-          minWidth: WO_TABLE_MIN_WIDTH,
-          borderCollapse: "collapse",
+    <>
+      <WoTableShell>
+        <table
+          style={{
+            width: "100%",
+            minWidth: WO_TABLE_MIN_WIDTH,
+            borderCollapse: "collapse",
+          }}
+        >
+          <WoTableHead />
+          <WoTableBody
+            tableData={tableData}
+            renderRow={renderRow}
+            renderInlineRow={renderInlineRow}
+          />
+        </table>
+      </WoTableShell>
+
+      <DuplicateWoNumberDialog
+        open={duplicateRow != null}
+        existing={duplicateRow}
+        onDismiss={() => setDuplicateRow(null)}
+        onViewExisting={(row) => {
+          setDuplicateRow(null);
+          onOpenSlideOver(row, false);
         }}
-      >
-        <WoTableHead />
-        <WoTableBody
-          tableData={tableData}
-          renderRow={renderRow}
-          renderInlineRow={renderInlineRow}
-        />
-      </table>
-    </WoTableShell>
+      />
+    </>
   );
 }
diff --git a/src/test/app/(protected)/workorders/duplicate-wo-number-dialog.test.tsx b/src/test/app/(protected)/workorders/duplicate-wo-number-dialog.test.tsx
new file mode 100644
index 00000000..5d126913
--- /dev/null
+++ b/src/test/app/(protected)/workorders/duplicate-wo-number-dialog.test.tsx
@@ -0,0 +1,58 @@
+import { fireEvent, screen } from "@testing-library/react";
+import { describe, expect, it, vi } from "vitest";
+import { DuplicateWoNumberDialog } from "@/app/(protected)/workorders/_components/list/duplicate-wo-number-dialog";
+import type { WorkOrderTableRow } from "@/domain/work-orders/types/work-order-table-row";
+import { renderWithProviders } from "@/test/test-utils";
+
+const existingRow = { id: "wo-99", woNumber: "12345678901" } as WorkOrderTableRow;
+
+describe("DuplicateWoNumberDialog", () => {
+  it("shows the duplicate title and work order number when open", () => {
+    renderWithProviders(
+      <DuplicateWoNumberDialog
+        open
+        existing={existingRow}
+        onDismiss={vi.fn()}
+        onViewExisting={vi.fn()}
+      />,
+    );
+
+    expect(screen.getByRole("dialog")).toBeInTheDocument();
+    expect(screen.getByText("Duplicate Work Order Number")).toBeInTheDocument();
+    expect(screen.getByText(/12345678901/)).toBeInTheDocument();
+  });
+
+  it("calls onViewExisting when View existing is clicked", () => {
+    const onViewExisting = vi.fn();
+
+    renderWithProviders(
+      <DuplicateWoNumberDialog
+        open
+        existing={existingRow}
+        onDismiss={vi.fn()}
+        onViewExisting={onViewExisting}
+      />,
+    );
+
+    fireEvent.click(screen.getByRole("button", { name: "View existing" }));
+
+    expect(onViewExisting).toHaveBeenCalledWith(existingRow);
+  });
+
+  it("calls onDismiss when Dismiss is clicked", () => {
+    const onDismiss = vi.fn();
+
+    renderWithProviders(
+      <DuplicateWoNumberDialog
+        open
+        existing={existingRow}
+        onDismiss={onDismiss}
+        onViewExisting={vi.fn()}
+      />,
+    );
+
+    fireEvent.click(screen.getByRole("button", { name: "Dismiss" }));
+
+    expect(onDismiss).toHaveBeenCalledTimes(1);
+  });
+});
diff --git a/src/test/app/(protected)/workorders/use-wo-table-row-handlers-duplicate.test.ts b/src/test/app/(protected)/workorders/use-wo-table-row-handlers-duplicate.test.ts
new file mode 100644
index 00000000..df563025
--- /dev/null
+++ b/src/test/app/(protected)/workorders/use-wo-table-row-handlers-duplicate.test.ts
@@ -0,0 +1,43 @@
+import { renderHook } from "@testing-library/react";
+import { describe, expect, it, vi } from "vitest";
+import { useWoTableRowHandlers } from "@/app/(protected)/workorders/_components/list/table/use-wo-table-row-handlers";
+import type { WorkOrderTableRow } from "@/domain/work-orders/types/work-order-table-row";
+
+const existingRow = { id: "wo-99", woNumber: "12345678901" } as WorkOrderTableRow;
+
+function buildTableData() {
+  return {
+    dragState: { current: { dragId: null, overId: null } },
+    setDragViz: vi.fn(),
+    reorderRows: vi.fn(),
+    endDrag: vi.fn(),
+    setUnschedOpen: vi.fn(),
+    triggerFlash: vi.fn(),
+    setSelectedId: vi.fn(),
+  } as never;
+}
+
+describe("useWoTableRowHandlers onDuplicateFound", () => {
+  it("delegates to onDuplicateFound instead of opening the slide-over", () => {
+    const onDuplicateFound = vi.fn();
+    const onOpenSlideOver = vi.fn();
+
+    const { result } = renderHook(() =>
+      useWoTableRowHandlers({
+        tableData: buildTableData(),
+        weekMonday: "2026-07-20",
+        onWeekChange: vi.fn(),
+        onOpenSlideOver,
+        onOpenMedia: vi.fn(),
+        onPatch: vi.fn(),
+        onScheduleHighlight: vi.fn(),
+        onDuplicateFound,
+      }),
+    );
+
+    result.current.onDuplicateFound?.(existingRow);
+
+    expect(onDuplicateFound).toHaveBeenCalledWith(existingRow);
+    expect(onOpenSlideOver).not.toHaveBeenCalled();
+  });
+});
diff --git a/tmp/pr-descriptions/pr8-duplicate-dialog.md b/tmp/pr-descriptions/pr8-duplicate-dialog.md
new file mode 100644
index 00000000..77f29a83
--- /dev/null
+++ b/tmp/pr-descriptions/pr8-duplicate-dialog.md
@@ -0,0 +1,17 @@
+## Summary
+
+- Show a confirmation dialog when inline WO number editing detects a duplicate instead of navigating immediately to the existing work order.
+- Dialog title: **Duplicate Work Order Number**; actions: **View existing** (opens the existing WO slide-over) and **Dismiss** (closes the dialog and keeps the current row editable).
+- Duplicate scan logic in `editable-wo-number-cell.tsx` is unchanged; only the post-detection UX is updated.
+
+## Test plan
+
+- [ ] Edit a WO number in the table to match an existing row → dialog opens with the duplicate number in the message.
+- [ ] Click **Dismiss** → dialog closes; edited row keeps its original number.
+- [ ] Repeat duplicate entry → click **View existing** → navigates to `/workorders/{id}` for the existing row.
+- [ ] Confirm non-duplicate WO number edits still save normally.
+
+## Out of scope
+
+- Server-side uniqueness (422) handling
+- SH provisional numbering