diff --git a/src/lib/collection-ai-ticks.test.ts b/src/lib/collection-ai-ticks.test.ts
new file mode 100644
index 0000000..76982b9
--- /dev/null
+++ b/src/lib/collection-ai-ticks.test.ts
@@ -0,0 +1,123 @@
+import { describe, it, expect } from "vitest";
+import {
+  computeLineTicks,
+  allGreen,
+  showsAiFilledSku,
+  normaliseCode,
+  type TickRow,
+} from "./collection-ai-ticks";
+import type { CollectionAiCheck, CollectionDocLine } from "@/lib/types";
+
+const line = (o: Partial<CollectionDocLine> = {}): CollectionDocLine => ({
+  line_no: 1,
+  code: "SM293306016",
+  description: "x",
+  quantity: 40,
+  unit: "ea",
+  unit_price: 0.2,
+  line_total: null,
+  to_follow: null,
+  price_note: "",
+  ...o,
+});
+const check = (o: Partial<CollectionAiCheck> = {}): CollectionAiCheck => ({
+  read_id: "r1",
+  document_no: "D1",
+  doc_date: "",
+  doc_type: "tax_invoice",
+  doc_line: line(),
+  same_item: "sure",
+  reason: "",
+  sku_filled_value: "",
+  findings: [],
+  checked_at: "",
+  model: "",
+  ...o,
+});
+const row = (o: Partial<TickRow> = {}): TickRow => ({
+  sku: "SM293306016",
+  qty_collected: 40,
+  cost_price: 0.2,
+  order_qty: 40,
+  ...o,
+});
+
+describe("normaliseCode", () => {
+  it("uppercases and strips non-alphanumerics", () => {
+    expect(normaliseCode(" sm-29/33 ")).toBe("SM2933");
+    expect(normaliseCode(null)).toBe("");
+  });
+});
+
+describe("computeLineTicks", () => {
+  it("no pairing gives all red", () => {
+    expect(computeLineTicks(row(), check({ doc_line: null }))).toEqual({
+      sku: "red", qty: "red", desc: "red", price: "red",
+    });
+  });
+  it("sku ticks", () => {
+    expect(computeLineTicks(row({ sku: "sm293306016" }), check()).sku).toBe("green");
+    expect(
+      computeLineTicks(row({ sku: "OUR-1" }), check({ sku_filled_value: "OUR-1" })).sku,
+    ).toBe("green");
+    expect(computeLineTicks(row({ sku: "OTHER" }), check()).sku).toBe("amber");
+    expect(
+      computeLineTicks(row(), check({ doc_line: line({ code: "" }) })).sku,
+    ).toBe("grey");
+    expect(computeLineTicks(row({ sku: "" }), check()).sku).toBe("red");
+  });
+  it("qty ticks", () => {
+    expect(computeLineTicks(row(), check()).qty).toBe("green");
+    expect(
+      computeLineTicks(
+        row({ qty_collected: 5, order_qty: 8 }),
+        check({ doc_line: line({ quantity: 5 }) }),
+      ).qty,
+    ).toBe("amber");
+    expect(
+      computeLineTicks(row({ qty_collected: 3 }), check({ doc_line: line({ quantity: 4 }) })).qty,
+    ).toBe("red");
+    expect(
+      computeLineTicks(row(), check({ doc_line: line({ quantity: null }) })).qty,
+    ).toBe("grey");
+    expect(
+      computeLineTicks(row({ order_qty: 0, quantity: 40 }), check()).qty,
+    ).toBe("green");
+  });
+  it("desc ticks", () => {
+    expect(computeLineTicks(row(), check({ same_item: "sure" })).desc).toBe("green");
+    expect(computeLineTicks(row(), check({ same_item: "likely" })).desc).toBe("amber");
+    expect(computeLineTicks(row(), check({ same_item: "different" })).desc).toBe("red");
+    expect(computeLineTicks(row(), check({ same_item: null })).desc).toBe("red");
+  });
+  it("price ticks", () => {
+    expect(computeLineTicks(row(), check()).price).toBe("green");
+    expect(
+      computeLineTicks(row({ cost_price: 0.345 }), check({ doc_line: line({ unit_price: 0.33 }) })).price,
+    ).toBe("red");
+    expect(
+      computeLineTicks(row({ cost_price: 14.515 }), check({ doc_line: line({ unit_price: 14.51 }) })).price,
+    ).toBe("green");
+    expect(computeLineTicks(row(), check({ doc_type: "delivery_note" })).price).toBe("grey");
+    expect(
+      computeLineTicks(row(), check({ doc_line: line({ unit_price: null }) })).price,
+    ).toBe("grey");
+    expect(computeLineTicks(row({ cost_price: null }), check()).price).toBe("red");
+  });
+});
+
+describe("allGreen", () => {
+  it("only when all four green", () => {
+    expect(allGreen({ sku: "green", qty: "green", desc: "green", price: "green" })).toBe(true);
+    expect(allGreen({ sku: "green", qty: "green", desc: "green", price: "grey" })).toBe(false);
+  });
+});
+
+describe("showsAiFilledSku", () => {
+  it("true while sku still equals filled value, false after rep edits", () => {
+    const c = check({ sku_filled_value: "OUR-1" });
+    expect(showsAiFilledSku({ sku: "OUR-1" }, c)).toBe(true);
+    expect(showsAiFilledSku({ sku: "OUR-2" }, c)).toBe(false);
+    expect(showsAiFilledSku({ sku: "OUR-1" }, null)).toBe(false);
+  });
+});
diff --git a/src/lib/collection-ai-ticks.ts b/src/lib/collection-ai-ticks.ts
new file mode 100644
index 0000000..fdae0eb
--- /dev/null
+++ b/src/lib/collection-ai-ticks.ts
@@ -0,0 +1,87 @@
+import type { CollectionAiCheck } from "@/lib/types";
+
+export type TickState = "green" | "amber" | "red" | "grey";
+
+export interface LineTicks {
+  sku: TickState;
+  qty: TickState;
+  desc: TickState;
+  price: TickState;
+}
+
+export type TickRow = {
+  sku?: string;
+  qty_collected?: number;
+  cost_price?: number | null;
+  order_qty?: number;
+  quantity?: number;
+};
+
+const PRICE_TOLERANCE = 0.01;
+const FLOAT_EPSILON = 1e-9;
+
+/** Uppercase, A-Z0-9 only. */
+export function normaliseCode(code: string | null | undefined): string {
+  return (code ?? "").toUpperCase().replace(/[^A-Z0-9]/g, "");
+}
+
+export function computeLineTicks(row: TickRow, check: CollectionAiCheck): LineTicks {
+  const doc = check.doc_line;
+  if (!doc) return { sku: "red", qty: "red", desc: "red", price: "red" };
+
+  // SKU
+  const rowSku = row.sku ?? "";
+  const docCode = normaliseCode(doc.code);
+  let sku: TickState;
+  if (!docCode) sku = "grey";
+  else if (!rowSku.trim()) sku = "red";
+  else if (
+    normaliseCode(rowSku) === docCode ||
+    (check.sku_filled_value !== "" && rowSku === check.sku_filled_value)
+  )
+    sku = "green";
+  else sku = "amber";
+
+  // Qty
+  let qty: TickState;
+  if (doc.quantity == null) qty = "grey";
+  else if (doc.quantity !== row.qty_collected) qty = "red";
+  else {
+    const ordered = row.order_qty ? row.order_qty : (row.quantity ?? 0);
+    qty = ordered && ordered !== doc.quantity ? "amber" : "green";
+  }
+
+  // Description
+  const desc: TickState =
+    check.same_item === "sure"
+      ? "green"
+      : check.same_item === "likely"
+        ? "amber"
+        : "red";
+
+  // Price
+  let price: TickState;
+  if (check.doc_type === "delivery_note" || doc.unit_price == null) price = "grey";
+  else if (row.cost_price == null) price = "red";
+  else
+    price =
+      Math.abs(doc.unit_price - row.cost_price) <= PRICE_TOLERANCE + FLOAT_EPSILON
+        ? "green"
+        : "red";
+
+  return { sku, qty, desc, price };
+}
+
+export function allGreen(t: LineTicks): boolean {
+  return (
+    t.sku === "green" && t.qty === "green" && t.desc === "green" && t.price === "green"
+  );
+}
+
+/** True while the row SKU is still the value the AI filled in. */
+export function showsAiFilledSku(
+  row: TickRow,
+  check: CollectionAiCheck | null | undefined,
+): boolean {
+  return !!check && check.sku_filled_value !== "" && row.sku === check.sku_filled_value;
+}