fix(dn-pipeline): a PO line with no unit no longer blocks delivery

61 of 148 purchase_order_items have an empty unit. Blocking every
delivery against them rejects 41% of lines over a gap on the order.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/lib/dn-item-row.test.ts

@@ -69,6 +69,20 @@ describe("buildDeliveryNoteItemRows", () => {
     expect(rows[0].condition_notes).toContain("unknown_unit");
   });
 
+  it("passes the slip quantity through when the PO line has no unit", () => {
+    const { rows } = buildDeliveryNoteItemRows({
+      items: [{ description: "G6 Sub Base", qty: 12, unit: "ton", matched_po_item_id: "aaaaaaaaaaaaaaa" }],
+      poItems: [{ id: "aaaaaaaaaaaaaaa", unit: "" }],
+      confidence: 1,
+    });
+    expect(rows[0].qty_received).toBe(12);
+    expect(rows[0].qty_raw).toBe(12);
+    expect(rows[0].unit_raw).toBe("ton");
+    expect(rows[0].unit_converted).toBe(false);
+    expect(rows[0].purchase_order_item).toBe("aaaaaaaaaaaaaaa");
+    expect(rows[0].condition_notes).toContain("po unit missing");
+  });
+
   it("keeps an unmatched line at zero with no link", () => {
     const { rows } = buildDeliveryNoteItemRows({
       items: [{ description: "Mystery", qty: 4, unit: "kg" }],

src/lib/dn-item-row.ts

@@ -92,6 +92,13 @@ export function buildDeliveryNoteItemRows(
         // local fetch). Keep the link for the audit trail but do not
         // invent a quantity we cannot express in the right unit.
         failure = "po_item_unavailable";
+      } else if (!normaliseUnit(poItem.unit ?? null)) {
+        // No target unit to convert into. Keep the link and the slip's
+        // own number — the alternative is discarding a real delivery
+        // because the purchase order is missing a field.
+        qtyReceived = qty;
+        converted = false;
+        failure = "po unit missing";
       } else {
         const conv = convertQty(qty, normaliseUnit(unitRaw), normaliseUnit(poItem.unit));
         if (conv.ok) {

src/lib/dn-pipeline/checks.test.ts

@@ -171,6 +171,19 @@ describe("runNoteChecks", () => {
     expect(r.passed).toBe(false);
   });
 
+  it("skips units_convertible when the PO line has no unit", () => {
+    const ctx = { ...CTX, poItems: [{ id: "bxqbo8rs04pjqwc", description: "G6 Sub Base", unit: "" }] };
+    const r = byId(runNoteChecks(note(), ctx), "units_convertible");
+    expect(r.passed).toBeNull();
+    expect(r.reason).toContain("no unit");
+  });
+
+  it("still fails when the SLIP line has no unit", () => {
+    const n = note({ items: [{ description: "G6 Sub Base", qty: 5, unit: null, unit_price: null }] });
+    const r = byId(runNoteChecks(n, CTX), "units_convertible");
+    expect(r.passed).toBe(false);
+  });
+
   it("fails when the note number is already in delivery_notes", () => {
     const ctx = { ...CTX, existingNoteNumbers: new Set(["DQ0010107"]) };
     const r = byId(runNoteChecks(note(), ctx), "not_duplicate");

src/lib/dn-pipeline/checks.ts

@@ -147,15 +147,32 @@ function unitsConvertible(note: NoteSegment, ctx: NoteCheckContext): CheckResult
     return { id: "units_convertible", passed: null, reason: "no purchase order lines to convert into" };
   }
   const bad: string[] = [];
+  const missingPoUnit: string[] = [];
   for (const it of note.items) {
     const poItem = matchPoItem(it.description, ctx.poItems);
     if (!poItem) continue; // product_matched already reports this
+    // A PO line with no stated unit cannot be converted into. That is a
+    // purchasing data gap, not a delivery problem — 61 of 148 PO lines
+    // are affected, and blocking them all would reject 41% of deliveries
+    // over a missing field on the order.
+    if (!normaliseUnit(poItem.unit ?? null)) {
+      missingPoUnit.push(it.description);
+      continue;
+    }
     const conv = convertQty(it.qty, normaliseUnit(it.unit), normaliseUnit(poItem.unit ?? null));
     if (!conv.ok) bad.push(`${it.description} (${it.unit ?? "no unit"} → ${poItem.unit || "no unit"})`);
   }
-  return bad.length === 0
-    ? { id: "units_convertible", passed: true, reason: "all units convert" }
-    : { id: "units_convertible", passed: false, reason: `cannot convert: ${bad.join(", ")}` };
+  if (bad.length > 0) {
+    return { id: "units_convertible", passed: false, reason: `cannot convert: ${bad.join(", ")}` };
+  }
+  if (missingPoUnit.length > 0) {
+    return {
+      id: "units_convertible",
+      passed: null,
+      reason: `purchase order line has no unit: ${missingPoUnit.join(", ")}`,
+    };
+  }
+  return { id: "units_convertible", passed: true, reason: "all units convert" };
 }
 
 function notDuplicate(note: NoteSegment, ctx: NoteCheckContext): CheckResult {