diff --git a/src/lib/quote-assistant-review.test.ts b/src/lib/quote-assistant-review.test.ts
new file mode 100644
index 0000000..ccd2184
--- /dev/null
+++ b/src/lib/quote-assistant-review.test.ts
@@ -0,0 +1,141 @@
+import { describe, expect, it } from "vitest";
+import type { QuoteItemAiFill } from "@/lib/types";
+import {
+  aiRowClass,
+  buildAiReviewPatch,
+  isAiFillPending,
+  nextPricingSourceOnSave,
+} from "./quote-assistant-review";
+
+const NOW = new Date("2026-10-16T12:00:00.000Z");
+
+function fill(over: Partial<QuoteItemAiFill> = {}): QuoteItemAiFill {
+  return {
+    status: "filled",
+    stock_item_id: "s-1",
+    stock_item_name: "Bolt",
+    stock_item_sku: "B",
+    cost_price: 1.89,
+    selling_price: 3.4,
+    markup: 80,
+    supplier_id: "s1",
+    confidence: "high",
+    reason: "",
+    doubts: [],
+    candidates: [],
+    description_snapshot: "bolt",
+    model: "m",
+    attempted_at: NOW.toISOString(),
+    ...over,
+  };
+}
+
+const pending = { ai_fill: fill(), pricing_source: "ai_pos" };
+
+describe("isAiFillPending", () => {
+  it("is true only for an unreviewed filled ai_pos line", () => {
+    expect(isAiFillPending(pending)).toBe(true);
+  });
+  it("is false once reviewed", () => {
+    expect(
+      isAiFillPending({
+        ai_fill: fill({ reviewed_at: NOW.toISOString() }),
+        pricing_source: "ai_pos",
+      }),
+    ).toBe(false);
+  });
+  it("is false when a rep's save flipped pricing_source to manual", () => {
+    expect(isAiFillPending({ ai_fill: fill(), pricing_source: "manual" })).toBe(false);
+  });
+  it("is false for non-filled statuses and missing ai_fill", () => {
+    expect(isAiFillPending({ ai_fill: fill({ status: "no_match" }), pricing_source: "ai_pos" })).toBe(false);
+    expect(isAiFillPending({ ai_fill: null, pricing_source: "ai_pos" })).toBe(false);
+    expect(isAiFillPending({ pricing_source: "ai_pos" })).toBe(false);
+  });
+});
+
+describe("nextPricingSourceOnSave", () => {
+  it("keeps catalogue and ai_pos, otherwise manual", () => {
+    expect(nextPricingSourceOnSave("catalogue")).toBe("catalogue");
+    expect(nextPricingSourceOnSave("ai_pos")).toBe("ai_pos");
+    expect(nextPricingSourceOnSave("ai_email")).toBe("manual");
+    expect(nextPricingSourceOnSave("")).toBe("manual");
+    expect(nextPricingSourceOnSave(undefined)).toBe("manual");
+    expect(nextPricingSourceOnSave("manual")).toBe("manual");
+  });
+});
+
+describe("buildAiReviewPatch", () => {
+  const reviewer = { id: "u1", name: "Sam" };
+
+  it("records an unchanged acceptance", () => {
+    const patch = buildAiReviewPatch(
+      pending,
+      { cost_price: 1.89, selling_price: 3.4, supplier: "s1" },
+      reviewer,
+      NOW,
+    );
+    expect(patch.ai_fill).toMatchObject({
+      status: "filled",
+      accepted_unchanged: true,
+      supplier_changed: false,
+      reviewed_at: NOW.toISOString(),
+      reviewed_by: "Sam",
+    });
+  });
+
+  it("flags a changed selling price", () => {
+    const patch = buildAiReviewPatch(
+      pending,
+      { cost_price: 1.89, selling_price: 4, supplier: "s1" },
+      reviewer,
+      NOW,
+    );
+    expect(patch.ai_fill?.accepted_unchanged).toBe(false);
+  });
+
+  it("flags a changed cost price", () => {
+    const patch = buildAiReviewPatch(
+      pending,
+      { cost_price: 2, selling_price: 3.4, supplier: "s1" },
+      reviewer,
+      NOW,
+    );
+    expect(patch.ai_fill?.accepted_unchanged).toBe(false);
+  });
+
+  it("flags a different or cleared supplier", () => {
+    const changed = buildAiReviewPatch(
+      pending,
+      { cost_price: 1.89, selling_price: 3.4, supplier: "s2" },
+      reviewer,
+      NOW,
+    );
+    expect(changed.ai_fill?.supplier_changed).toBe(true);
+    const cleared = buildAiReviewPatch(
+      pending,
+      { cost_price: 1.89, selling_price: 3.4, supplier: null },
+      reviewer,
+      NOW,
+    );
+    expect(cleared.ai_fill?.supplier_changed).toBe(true);
+  });
+
+  it("returns an empty patch for a non-pending line", () => {
+    const saved = { cost_price: 1, selling_price: 2, supplier: null };
+    expect(
+      buildAiReviewPatch({ ai_fill: fill(), pricing_source: "manual" }, saved, reviewer, NOW),
+    ).toEqual({});
+    expect(
+      buildAiReviewPatch({ ai_fill: null, pricing_source: "ai_pos" }, saved, reviewer, NOW),
+    ).toEqual({});
+  });
+});
+
+describe("aiRowClass", () => {
+  it("highlights pending lines only", () => {
+    expect(aiRowClass(pending)).toBe("bg-ai/10");
+    expect(aiRowClass({ ai_fill: fill(), pricing_source: "manual" })).toBe("");
+    expect(aiRowClass({ ai_fill: null, pricing_source: "" })).toBe("");
+  });
+});
diff --git a/src/lib/quote-assistant-review.ts b/src/lib/quote-assistant-review.ts
new file mode 100644
index 0000000..51516e1
--- /dev/null
+++ b/src/lib/quote-assistant-review.ts
@@ -0,0 +1,65 @@
+/**
+ * quote-assistant-review — client-safe helpers for AI-filled quote lines.
+ *
+ * Imports only types, so Process-page components can use it directly.
+ *
+ * A line is "pending review" only when the AI filled it, nobody has
+ * reviewed it, AND `pricing_source` is still "ai_pos". A rep who saves a
+ * line from a stale page flips `pricing_source` to "manual"
+ * (`nextPricingSourceOnSave`), so their values win and the line stops
+ * being highlighted.
+ */
+import type { QuoteItem, QuoteItemAiFill } from "@/lib/types";
+
+type AiLine = Pick<QuoteItem, "ai_fill" | "pricing_source">;
+
+export function isAiFillPending(item: AiLine): boolean {
+  const fill = item.ai_fill;
+  return (
+    !!fill &&
+    fill.status === "filled" &&
+    !fill.reviewed_at &&
+    item.pricing_source === "ai_pos"
+  );
+}
+
+/** What `pricing_source` a human save should write, given the loaded value. */
+export function nextPricingSourceOnSave(
+  current: string | undefined,
+): "catalogue" | "ai_pos" | "manual" {
+  if (current === "catalogue" || current === "ai_pos") return current;
+  return "manual";
+}
+
+const sameMoney = (a: number, b: number) =>
+  Math.round((Number(a) || 0) * 100) === Math.round((Number(b) || 0) * 100);
+
+/**
+ * The `ai_fill` update recording that a person reviewed a pending AI fill.
+ * Returns `{}` for a line that isn't pending (nothing to record).
+ */
+export function buildAiReviewPatch(
+  item: AiLine,
+  saved: { cost_price: number; selling_price: number; supplier: string | null },
+  reviewer: { id?: string; name: string },
+  now: Date,
+): { ai_fill?: QuoteItemAiFill } {
+  if (!isAiFillPending(item) || !item.ai_fill) return {};
+  const fill = item.ai_fill;
+  return {
+    ai_fill: {
+      ...fill,
+      reviewed_at: now.toISOString(),
+      reviewed_by: reviewer.name,
+      accepted_unchanged:
+        sameMoney(saved.cost_price, fill.cost_price) &&
+        sameMoney(saved.selling_price, fill.selling_price),
+      supplier_changed: (saved.supplier ?? "") !== (fill.supplier_id ?? ""),
+    },
+  };
+}
+
+/** Row highlight for lines awaiting human review of an AI fill. */
+export function aiRowClass(item: AiLine): string {
+  return isAiFillPending(item) ? "bg-ai/10" : "";
+}
diff --git a/src/lib/server/quote-assistant-core.test.ts b/src/lib/server/quote-assistant-core.test.ts
new file mode 100644
index 0000000..fcdf574
--- /dev/null
+++ b/src/lib/server/quote-assistant-core.test.ts
@@ -0,0 +1,380 @@
+import { describe, expect, it } from "vitest";
+import type { QuoteItem, QuoteItemAiFill } from "@/lib/types";
+import type { StockCandidate } from "./quote-assistant-shortlist";
+import {
+  buildLinePatch,
+  isLineEligible,
+  isLineStillWritable,
+  meetsConfidence,
+  parseDecisions,
+  type AiLineDecision,
+} from "./quote-assistant-core";
+
+const NOW = new Date("2026-10-16T12:00:00.000Z");
+
+function aiFill(over: Partial<QuoteItemAiFill> = {}): QuoteItemAiFill {
+  return {
+    status: "no_match",
+    stock_item_id: null,
+    stock_item_name: "",
+    stock_item_sku: "",
+    cost_price: 0,
+    selling_price: 0,
+    markup: 0,
+    supplier_id: "",
+    confidence: null,
+    reason: "",
+    doubts: [],
+    candidates: [],
+    description_snapshot: "M10 bolt",
+    model: "m",
+    attempted_at: NOW.toISOString(),
+    ...over,
+  };
+}
+
+function line(over: Partial<QuoteItem> = {}): QuoteItem {
+  return {
+    id: "qi1",
+    quote: "q1",
+    description: "M10 bolt",
+    cost_price: 0,
+    selling_price: 0,
+    markup: 0,
+    supplier: "",
+    user_edited: false,
+    is_processed: false,
+    pricing_source: "ai_email",
+    pricing_notes: "",
+    moved_to_quote: "",
+    ai_fill: null,
+    ...over,
+  } as unknown as QuoteItem;
+}
+
+function cand(over: Partial<StockCandidate> = {}): StockCandidate {
+  return {
+    id: "s-1",
+    name: "M10 Bolt Zinc",
+    sku: "BLT10",
+    description: "",
+    notes: "",
+    unit: "EA",
+    cost_price: 1.89,
+    selling_price: 3.4,
+    markup: 80,
+    supplier_id: "s1",
+    supplier_name: "Supp",
+    score: 0.9,
+    ...over,
+  };
+}
+
+function decision(over: Partial<AiLineDecision> = {}): AiLineDecision {
+  return {
+    quote_item_id: "qi1",
+    stock_item_id: "s-1",
+    confidence: "high",
+    reason: "same bolt",
+    doubts: [],
+    ...over,
+  };
+}
+
+describe("isLineEligible", () => {
+  it("accepts a fresh unpriced AI-email line", () => {
+    expect(isLineEligible(line(), { now: NOW })).toBe(true);
+  });
+
+  it("treats null/undefined moved_to_quote as not moved", () => {
+    expect(isLineEligible(line({ moved_to_quote: null }), { now: NOW })).toBe(true);
+    expect(isLineEligible(line({ moved_to_quote: undefined }), { now: NOW })).toBe(true);
+  });
+
+  it.each([
+    ["has a cost", { cost_price: 5 }],
+    ["has a selling price", { selling_price: 5 }],
+    ["user edited", { user_edited: true }],
+    ["processed", { is_processed: true }],
+    ["manual pricing source", { pricing_source: "manual" }],
+    ["empty description", { description: "  " }],
+    ["moved to another quote", { moved_to_quote: "q2" }],
+  ] as [string, Partial<QuoteItem>][])("rejects when %s", (_n, over) => {
+    expect(isLineEligible(line(over), { now: NOW })).toBe(false);
+  });
+
+  it("skips no_match with an unchanged description", () => {
+    expect(isLineEligible(line({ ai_fill: aiFill() }), { now: NOW })).toBe(false);
+  });
+
+  it("retries no_match when the description changed", () => {
+    const item = line({
+      description: "M10 bolt zinc 50mm",
+      ai_fill: aiFill({ description_snapshot: "M10 bolt" }),
+    });
+    expect(isLineEligible(item, { now: NOW })).toBe(true);
+  });
+
+  it("retries no_match with the same snapshot when forced", () => {
+    expect(isLineEligible(line({ ai_fill: aiFill() }), { now: NOW, force: true })).toBe(true);
+  });
+
+  it("retries error lines only after an hour", () => {
+    const at = (mins: number) => new Date(NOW.getTime() - mins * 60_000).toISOString();
+    const old = line({ ai_fill: aiFill({ status: "error", attempted_at: at(61) }) });
+    const recent = line({ ai_fill: aiFill({ status: "error", attempted_at: at(59) }) });
+    expect(isLineEligible(old, { now: NOW })).toBe(true);
+    expect(isLineEligible(recent, { now: NOW })).toBe(false);
+    expect(isLineEligible(recent, { now: NOW, force: true })).toBe(true);
+  });
+
+  it("never lets force override a person's work", () => {
+    expect(isLineEligible(line({ user_edited: true }), { now: NOW, force: true })).toBe(false);
+    expect(isLineEligible(line({ cost_price: 2 }), { now: NOW, force: true })).toBe(false);
+  });
+});
+
+describe("isLineStillWritable", () => {
+  it("is true for an untouched unpriced line", () => {
+    expect(isLineStillWritable(line())).toBe(true);
+  });
+  it.each([
+    { cost_price: 1 },
+    { selling_price: 1 },
+    { user_edited: true },
+    { is_processed: true },
+  ] as Partial<QuoteItem>[])("is false after %o", (over) => {
+    expect(isLineStillWritable(line(over))).toBe(false);
+  });
+});
+
+describe("parseDecisions", () => {
+  const ids = new Set(["a", "b"]);
+
+  it("drops unknown ids and keeps the first of duplicates", () => {
+    const out = parseDecisions(
+      {
+        decisions: [
+          { quote_item_id: "zzz", stock_item_id: "s", confidence: "high" },
+          { quote_item_id: "a", stock_item_id: "first", confidence: "high" },
+          { quote_item_id: "a", stock_item_id: "second", confidence: "low" },
+        ],
+      },
+      ids,
+    );
+    expect([...out.keys()]).toEqual(["a"]);
+    expect(out.get("a")?.stock_item_id).toBe("first");
+  });
+
+  it("accepts a bare array too", () => {
+    const out = parseDecisions([{ quote_item_id: "b", stock_item_id: null }], ids);
+    expect(out.get("b")?.stock_item_id).toBeNull();
+  });
+
+  it("nulls invalid confidence and coerces bad doubts", () => {
+    const out = parseDecisions(
+      [{ quote_item_id: "a", stock_item_id: "s", confidence: "certain", doubts: "nope", reason: 5 }],
+      ids,
+    );
+    const d = out.get("a")!;
+    expect(d.confidence).toBeNull();
+    expect(d.doubts).toEqual([]);
+    expect(d.reason).toBe("");
+  });
+
+  it("returns empty for garbage", () => {
+    expect(parseDecisions(null, ids).size).toBe(0);
+    expect(parseDecisions("x", ids).size).toBe(0);
+    expect(parseDecisions({ decisions: "x" }, ids).size).toBe(0);
+  });
+});
+
+describe("meetsConfidence", () => {
+  it("compares against the minimum", () => {
+    expect(meetsConfidence("medium", "medium")).toBe(true);
+    expect(meetsConfidence("high", "medium")).toBe(true);
+    expect(meetsConfidence("low", "medium")).toBe(false);
+    expect(meetsConfidence("medium", "high")).toBe(false);
+    expect(meetsConfidence("high", "high")).toBe(true);
+    expect(meetsConfidence(null, "medium")).toBe(false);
+    expect(meetsConfidence(null, "high")).toBe(false);
+  });
+});
+
+describe("buildLinePatch", () => {
+  const base = { minConfidence: "medium" as const, model: "MiniMax-M2", now: NOW };
+
+  it("fills from the chosen candidate", () => {
+    const patch = buildLinePatch({
+      ...base,
+      item: line(),
+      decision: decision(),
+      candidates: [cand()],
+    });
+    expect(patch).toMatchObject({
+      cost_price: 1.89,
+      selling_price: 3.4,
+      markup: 80,
+      supplier: "s1",
+      pricing_source: "ai_pos",
+    });
+    expect(patch.pricing_notes).toBe("AI: matched POS 'M10 Bolt Zinc' (high)");
+    const fill = patch.ai_fill as QuoteItemAiFill;
+    expect(fill).toMatchObject({
+      status: "filled",
+      stock_item_id: "s-1",
+      stock_item_name: "M10 Bolt Zinc",
+      stock_item_sku: "BLT10",
+      cost_price: 1.89,
+      selling_price: 3.4,
+      markup: 80,
+      supplier_id: "s1",
+      confidence: "high",
+      description_snapshot: "M10 bolt",
+      model: "MiniMax-M2",
+      attempted_at: NOW.toISOString(),
+    });
+    expect(fill.price_from_default_markup).toBeFalsy();
+    expect(patch).not.toHaveProperty("sku");
+    expect(patch).not.toHaveProperty("is_processed");
+    expect(patch).not.toHaveProperty("user_edited");
+  });
+
+  it("uses the default markup when the POS item has no selling price", () => {
+    const patch = buildLinePatch({
+      ...base,
+      item: line(),
+      decision: decision(),
+      candidates: [cand({ cost_price: 10, selling_price: 0, markup: 0 })],
+    });
+    expect(patch.selling_price).toBe(18);
+    expect(patch.markup).toBe(80);
+    const fill = patch.ai_fill as QuoteItemAiFill;
+    expect(fill.price_from_default_markup).toBe(true);
+    expect(patch.pricing_notes).toBe(
+      "AI: matched POS 'M10 Bolt Zinc' (high). Selling price from default markup.",
+    );
+  });
+
+  it("derives markup when the POS item has prices but no markup", () => {
+    const patch = buildLinePatch({
+      ...base,
+      item: line(),
+      decision: decision(),
+      candidates: [cand({ cost_price: 10, selling_price: 15, markup: 0 })],
+    });
+    expect(patch.selling_price).toBe(15);
+    expect(patch.markup).toBe(50);
+  });
+
+  it("is no_match with no price keys when the candidate has no cost", () => {
+    const patch = buildLinePatch({
+      ...base,
+      item: line(),
+      decision: decision(),
+      candidates: [cand({ cost_price: 0 })],
+    });
+    const fill = patch.ai_fill as QuoteItemAiFill;
+    expect(fill.status).toBe("no_match");
+    for (const k of ["cost_price", "selling_price", "markup", "supplier", "pricing_source"]) {
+      expect(patch).not.toHaveProperty(k);
+    }
+    expect(fill).toMatchObject({
+      stock_item_id: null,
+      cost_price: 0,
+      selling_price: 0,
+      markup: 0,
+      supplier_id: "",
+    });
+  });
+
+  it("is no_match for low confidence and lists up to 5 candidates", () => {
+    const many = Array.from({ length: 7 }, (_, i) => cand({ id: `s-${i + 1}`, name: `n${i}` }));
+    const patch = buildLinePatch({
+      ...base,
+      item: line(),
+      decision: decision({ confidence: "low" }),
+      candidates: many,
+    });
+    const fill = patch.ai_fill as QuoteItemAiFill;
+    expect(fill.status).toBe("no_match");
+    expect(fill.confidence).toBe("low");
+    expect(fill.stock_item_id).toBeNull();
+    expect(fill.candidates).toHaveLength(5);
+    expect(fill.candidates[0]).toEqual({
+      id: "s-1",
+      name: "n0",
+      sku: "BLT10",
+      cost_price: 1.89,
+      selling_price: 3.4,
+    });
+    expect(patch).not.toHaveProperty("cost_price");
+    expect(patch).not.toHaveProperty("pricing_source");
+  });
+
+  it("is no_match when the chosen id is not among the candidates", () => {
+    const patch = buildLinePatch({
+      ...base,
+      item: line(),
+      decision: decision({ stock_item_id: "not-there" }),
+      candidates: [cand()],
+    });
+    expect((patch.ai_fill as QuoteItemAiFill).status).toBe("no_match");
+    expect(patch).not.toHaveProperty("cost_price");
+  });
+
+  it("is no_match when there is no decision for the line", () => {
+    const patch = buildLinePatch({ ...base, item: line(), decision: null, candidates: [cand()] });
+    expect((patch.ai_fill as QuoteItemAiFill).status).toBe("no_match");
+  });
+
+  it("sets pricing_notes on no_match only when empty", () => {
+    const empty = buildLinePatch({ ...base, item: line(), decision: null, candidates: [cand()] });
+    expect(empty.pricing_notes).toBe("AI: no confident POS match — see closest items.");
+    const kept = buildLinePatch({
+      ...base,
+      item: line({ pricing_notes: "Rep note" }),
+      decision: null,
+      candidates: [cand()],
+    });
+    expect(kept).not.toHaveProperty("pricing_notes");
+  });
+
+  it("records no_candidates", () => {
+    const patch = buildLinePatch({
+      ...base,
+      item: line(),
+      decision: null,
+      candidates: [],
+      status: "no_candidates",
+    });
+    const fill = patch.ai_fill as QuoteItemAiFill;
+    expect(fill.status).toBe("no_candidates");
+    expect(fill.candidates).toEqual([]);
+    expect(patch).not.toHaveProperty("cost_price");
+    expect(patch.pricing_notes).toBe("AI: no confident POS match — see closest items.");
+  });
+
+  it("records error without touching prices or notes", () => {
+    const patch = buildLinePatch({
+      ...base,
+      item: line(),
+      decision: null,
+      candidates: [cand()],
+      status: "error",
+    });
+    const fill = patch.ai_fill as QuoteItemAiFill;
+    expect(fill.status).toBe("error");
+    expect(fill.attempted_at).toBe(NOW.toISOString());
+    for (const k of [
+      "cost_price",
+      "selling_price",
+      "markup",
+      "supplier",
+      "pricing_source",
+      "pricing_notes",
+    ]) {
+      expect(patch).not.toHaveProperty(k);
+    }
+  });
+});
diff --git a/src/lib/server/quote-assistant-core.ts b/src/lib/server/quote-assistant-core.ts
new file mode 100644
index 0000000..1a51294
--- /dev/null
+++ b/src/lib/server/quote-assistant-core.ts
@@ -0,0 +1,227 @@
+/**
+ * quote-assistant-core — pure decision logic for the AI quote assistant.
+ *
+ * No I/O here: these functions decide which quote lines the AI may touch,
+ * parse/validate what the AI returned, and build the PocketBase patch to
+ * write. The runner (later task) does the fetching, the AI call and the
+ * writing, and re-reads each line with `isLineStillWritable` right before
+ * writing.
+ *
+ * Guarantees encoded here:
+ *  - the AI never writes a line a person has priced/edited/processed;
+ *  - prices come only from the chosen POS candidate (never from the AI);
+ *  - the POS SKU stays in `ai_fill`, never on the line's own `sku`;
+ *  - `is_processed` / `user_edited` are never set.
+ */
+import type {
+  AiFillCandidate,
+  AiFillConfidence,
+  QuoteItem,
+  QuoteItemAiFill,
+} from "@/lib/types";
+import type { StockCandidate } from "@/lib/server/quote-assistant-shortlist";
+import {
+  DEFAULT_MARKUP_MULTIPLIER,
+  DEFAULT_MARKUP_PERCENT,
+  round2,
+} from "@/lib/server/stock-default-markup-service";
+
+export const ELIGIBLE_QUOTE_STATUSES = ["new", "follow_up", "claimed"] as const;
+export const ERROR_RETRY_MS = 60 * 60 * 1000;
+
+const MAX_LISTED_CANDIDATES = 5;
+const NO_MATCH_NOTE = "AI: no confident POS match — see closest items.";
+
+export interface AiLineDecision {
+  quote_item_id: string;
+  stock_item_id: string | null;
+  confidence: AiFillConfidence | null;
+  reason: string;
+  doubts: string[];
+}
+
+/** True when the line carries any price (cost or selling). */
+function hasPrice(item: QuoteItem): boolean {
+  return (Number(item.cost_price) || 0) > 0 || (Number(item.selling_price) || 0) > 0;
+}
+
+/** A person has not touched the line and no price is on it. */
+export function isLineStillWritable(item: QuoteItem): boolean {
+  return !hasPrice(item) && !item.user_edited && !item.is_processed;
+}
+
+/** Should this line be sent to the AI on this run? */
+export function isLineEligible(
+  item: QuoteItem,
+  opts: { force?: boolean; now: Date },
+): boolean {
+  if (!isLineStillWritable(item)) return false;
+  if (item.pricing_source === "manual") return false;
+  const description = (item.description || "").trim();
+  if (!description) return false;
+  if (item.moved_to_quote) return false;
+
+  const prior = item.ai_fill;
+  if (!prior || opts.force) return true;
+
+  if (prior.status === "error") {
+    const at = Date.parse(prior.attempted_at);
+    // Unparseable timestamp: don't wedge the line forever.
+    return Number.isNaN(at) || opts.now.getTime() - at > ERROR_RETRY_MS;
+  }
+
+  // Tried before (filled-then-cleared, no_match, no_candidates): only retry
+  // when the description changed since the attempt.
+  return prior.description_snapshot !== item.description;
+}
+
+const CONFIDENCE_RANK: Record<AiFillConfidence, number> = { low: 1, medium: 2, high: 3 };
+
+export function meetsConfidence(
+  c: AiFillConfidence | null,
+  min: "high" | "medium",
+): boolean {
+  if (!c) return false;
+  return CONFIDENCE_RANK[c] >= CONFIDENCE_RANK[min];
+}
+
+function asConfidence(v: unknown): AiFillConfidence | null {
+  return v === "high" || v === "medium" || v === "low" ? v : null;
+}
+
+/**
+ * Validate the AI's JSON. Accepts `{ decisions: [...] }` or a bare array.
+ * Unknown line ids are dropped, the first decision per id wins, and
+ * anything malformed degrades to null/empty rather than throwing.
+ */
+export function parseDecisions(
+  raw: unknown,
+  requestedIds: ReadonlySet<string>,
+): Map<string, AiLineDecision> {
+  const out = new Map<string, AiLineDecision>();
+  const list = Array.isArray(raw)
+    ? raw
+    : raw && typeof raw === "object" && Array.isArray((raw as { decisions?: unknown }).decisions)
+      ? (raw as { decisions: unknown[] }).decisions
+      : [];
+
+  for (const entry of list) {
+    if (!entry || typeof entry !== "object") continue;
+    const e = entry as Record<string, unknown>;
+    const id = typeof e.quote_item_id === "string" ? e.quote_item_id : "";
+    if (!id || !requestedIds.has(id) || out.has(id)) continue;
+    out.set(id, {
+      quote_item_id: id,
+      stock_item_id:
+        typeof e.stock_item_id === "string" && e.stock_item_id ? e.stock_item_id : null,
+      confidence: asConfidence(e.confidence),
+      reason: typeof e.reason === "string" ? e.reason : "",
+      doubts: Array.isArray(e.doubts)
+        ? e.doubts.filter((d): d is string => typeof d === "string")
+        : [],
+    });
+  }
+  return out;
+}
+
+function listCandidates(candidates: StockCandidate[]): AiFillCandidate[] {
+  return candidates.slice(0, MAX_LISTED_CANDIDATES).map((c) => ({
+    id: c.id,
+    name: c.name,
+    sku: c.sku,
+    cost_price: c.cost_price,
+    selling_price: c.selling_price,
+  }));
+}
+
+/**
+ * Build the PB patch for one line. Fills only when the decision picked a
+ * real candidate with a cost at/above the minimum confidence; otherwise
+ * records `no_match` (or the forced `no_candidates` / `error` status) and
+ * leaves every price field alone.
+ *
+ * For non-fill statuses `ai_fill.stock_item_id` is always null and the
+ * numeric fields are 0 — the closest options live in `ai_fill.candidates`.
+ */
+export function buildLinePatch(args: {
+  item: QuoteItem;
+  decision: AiLineDecision | null;
+  candidates: StockCandidate[];
+  minConfidence: "high" | "medium";
+  model: string;
+  now: Date;
+  status?: "no_candidates" | "error";
+}): Record<string, unknown> {
+  const { item, decision, candidates, minConfidence, model, now, status } = args;
+
+  const common = {
+    confidence: decision?.confidence ?? null,
+    reason: decision?.reason ?? "",
+    doubts: decision?.doubts ?? [],
+    candidates: listCandidates(candidates),
+    description_snapshot: item.description,
+    model,
+    attempted_at: now.toISOString(),
+  };
+
+  const chosen =
+    !status && decision?.stock_item_id
+      ? candidates.find((c) => c.id === decision.stock_item_id)
+      : undefined;
+  const cost = chosen ? round2(Number(chosen.cost_price) || 0) : 0;
+
+  if (chosen && cost > 0 && meetsConfidence(decision?.confidence ?? null, minConfidence)) {
+    const posSelling = round2(Number(chosen.selling_price) || 0);
+    const fromDefault = posSelling <= 0;
+    const selling = fromDefault ? round2(cost * DEFAULT_MARKUP_MULTIPLIER) : posSelling;
+    const posMarkup = Number(chosen.markup) || 0;
+    const markup = fromDefault
+      ? DEFAULT_MARKUP_PERCENT
+      : posMarkup > 0
+        ? posMarkup
+        : round2((selling / cost - 1) * 100);
+
+    const aiFill: QuoteItemAiFill = {
+      ...common,
+      status: "filled",
+      stock_item_id: chosen.id,
+      stock_item_name: chosen.name,
+      stock_item_sku: chosen.sku,
+      cost_price: cost,
+      selling_price: selling,
+      markup,
+      supplier_id: chosen.supplier_id,
+      ...(fromDefault ? { price_from_default_markup: true } : {}),
+    };
+    const patch: Record<string, unknown> = {
+      cost_price: cost,
+      selling_price: selling,
+      markup,
+      pricing_source: "ai_pos",
+      pricing_notes:
+        `AI: matched POS '${chosen.name}' (${decision?.confidence})` +
+        (fromDefault ? ". Selling price from default markup." : ""),
+      ai_fill: aiFill,
+    };
+    if (chosen.supplier_id) patch.supplier = chosen.supplier_id;
+    return patch;
+  }
+
+  const aiFill: QuoteItemAiFill = {
+    ...common,
+    status: status ?? "no_match",
+    stock_item_id: null,
+    stock_item_name: "",
+    stock_item_sku: "",
+    cost_price: 0,
+    selling_price: 0,
+    markup: 0,
+    supplier_id: "",
+  };
+  const patch: Record<string, unknown> = { ai_fill: aiFill };
+  // Don't overwrite a rep's note, and an error says nothing about the match.
+  if (status !== "error" && !(item.pricing_notes || "").trim()) {
+    patch.pricing_notes = NO_MATCH_NOTE;
+  }
+  return patch;
+}