diff --git a/src/lib/storefront-chat/upsells.test.ts b/src/lib/storefront-chat/upsells.test.ts
index 6423807..935a2ec 100644
--- a/src/lib/storefront-chat/upsells.test.ts
+++ b/src/lib/storefront-chat/upsells.test.ts
@@ -43,7 +43,12 @@ describe("automatic storefront upsells", () => {
 
     it("returns no upsell when the AI chooses null", () => {
         const result = parseAiUpsellChoice(
-            JSON.stringify({ productId: null, reason: "No clearly complementary product." }),
+            JSON.stringify({
+                productId: null,
+                relationshipType: "uncertain",
+                confidence: 0,
+                reason: "No clearly complementary product.",
+            }),
             [
                 {
                     title: "Candidate Product",
@@ -61,9 +66,64 @@ describe("automatic storefront upsells", () => {
         expect(result).toBeNull()
     })
 
+    it("rejects AI choices marked as substitutes", () => {
+        const result = parseAiUpsellChoice(
+            JSON.stringify({
+                productId: "candidate-1",
+                relationshipType: "substitute",
+                confidence: 0.9,
+                reason: "This is an alternative, not an add-on.",
+            }),
+            [
+                {
+                    title: "Candidate Product",
+                    productType: "Same Category",
+                    details: null,
+                    product: {
+                        productId: "candidate-1",
+                        title: "Candidate Product",
+                        variantId: "v-candidate",
+                    },
+                },
+            ],
+        )
+
+        expect(result).toBeNull()
+    })
+
+    it("accepts high-confidence complementary AI choices", () => {
+        const result = parseAiUpsellChoice(
+            JSON.stringify({
+                productId: "candidate-1",
+                relationshipType: "complementary_accessory",
+                confidence: 0.88,
+                reason: "This is used together with the base product.",
+            }),
+            [
+                {
+                    title: "Candidate Product",
+                    productType: "Accessory",
+                    details: null,
+                    product: {
+                        productId: "candidate-1",
+                        title: "Candidate Product",
+                        variantId: "v-candidate",
+                    },
+                },
+            ],
+        )
+
+        expect(result?.productId).toBe("candidate-1")
+    })
+
     it("only accepts AI choices that exist in the candidate list", () => {
         const result = parseAiUpsellChoice(
-            JSON.stringify({ productId: "unknown-product", reason: "Not in the provided list." }),
+            JSON.stringify({
+                productId: "unknown-product",
+                relationshipType: "complementary_accessory",
+                confidence: 0.9,
+                reason: "Not in the provided list.",
+            }),
             [
                 {
                     title: "Candidate Product",
diff --git a/src/lib/storefront-chat/upsells.ts b/src/lib/storefront-chat/upsells.ts
index 5b175ed..9b0fb7c 100644
--- a/src/lib/storefront-chat/upsells.ts
+++ b/src/lib/storefront-chat/upsells.ts
@@ -21,6 +21,14 @@ type UpsellCatalogCandidate = {
     details: string | null
 }
 
+const ACCEPTED_UPSELL_RELATIONSHIPS = new Set([
+    "complementary_accessory",
+    "care_item",
+    "consumable",
+    "bundle_addon",
+    "used_together",
+])
+
 function imageUrlFromImages(images: unknown): string | null {
     const rows = typeof images === "string"
         ? (() => {
@@ -104,9 +112,20 @@ export function parseAiUpsellChoice(
 ): StorefrontActionProduct | null {
     if (!content) return null
     try {
-        const parsed = JSON.parse(content) as { productId?: unknown }
+        const parsed = JSON.parse(content) as {
+            productId?: unknown
+            relationshipType?: unknown
+            confidence?: unknown
+        }
         const productId = typeof parsed.productId === "string" ? parsed.productId.trim() : ""
         if (!productId) return null
+        const relationshipType =
+            typeof parsed.relationshipType === "string"
+                ? parsed.relationshipType.trim().toLowerCase()
+                : ""
+        if (!ACCEPTED_UPSELL_RELATIONSHIPS.has(relationshipType)) return null
+        const confidence = Number(parsed.confidence)
+        if (!Number.isFinite(confidence) || confidence < 0.75) return null
         return candidates.find((candidate) => candidate.product.productId === productId)?.product ?? null
     } catch {
         return null
@@ -122,10 +141,14 @@ async function selectAiUpsellCandidate(params: {
 
     const system = [
         "You select one ecommerce upsell item, or no item.",
-        "Use only the provided catalog candidates. Return JSON only: {\"productId\":\"...\"|null,\"reason\":\"...\"}.",
-        "A valid upsell must be clearly complementary to the base product: accessory, care item, consumable, add-on, matching bundle item, or item normally used together.",
-        "Do not choose substitutes or alternatives to the same requested product type, even if they share words, audience, color, brand, season, or price.",
-        "If the relationship is weak, generic, or uncertain, return productId null.",
+        "Use only the provided catalog candidates.",
+        "Return JSON only: {\"productId\":\"...\"|null,\"relationshipType\":\"complementary_accessory|care_item|consumable|bundle_addon|used_together|substitute|alternative|same_category|unrelated|uncertain\",\"confidence\":0-1,\"reason\":\"...\"}.",
+        "A valid upsell must be something the customer would reasonably buy in addition to the base product and use together with it.",
+        "Choose only these valid relationship types: complementary_accessory, care_item, consumable, bundle_addon, used_together.",
+        "Do not choose substitutes, alternatives, or same-category replacements, even if they share words, audience, color, brand, season, style, or price.",
+        "Invalid examples: sandals -> flip flops, slippers -> shoes, rain boots -> formal shoes, one backpack -> another backpack.",
+        "Valid examples: shoes -> socks, shoes -> laces, leather shoes -> polish, phone -> case, backpack -> lunch box.",
+        "If there is no clear add-on with confidence at least 0.75, return productId null with relationshipType uncertain.",
     ].join(" ")
 
     const user = JSON.stringify({