From 4b6532c16fc453f311447c11c04a0de50d60ed26 Mon Sep 17 00:00:00 2001
From: amianthus <49116958+SirTenzin@users.noreply.github.com>
Date: Wed, 4 Mar 2026 10:18:59 +0000
Subject: [PATCH] =?UTF-8?q?fix:=20=F0=9F=90=9B=20only=20need=20one=20of=20?=
 =?UTF-8?q?amount=20or=20flat=5Famount=20or=20both?=
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---
 atmn/src/compose/models/planModels.ts | 13 ++++++++----
 typegen/genUtils/TypeGenerator.ts     |  1 +
 typegen/genUtils/atmnTypeHelpers.ts   | 29 ++++++++++++++++++++++-----
 3 files changed, 34 insertions(+), 9 deletions(-)

diff --git a/atmn/src/compose/models/planModels.ts b/atmn/src/compose/models/planModels.ts
index 0dc48b44..5413c7fe 100644
--- a/atmn/src/compose/models/planModels.ts
+++ b/atmn/src/compose/models/planModels.ts
@@ -52,7 +52,7 @@ export const PlanItemSchema = z.object({
     }),
     tiers: z.array(UsageTierSchema).optional().meta({
     description:
-    "Tiered pricing. Each tier's 'to' does NOT include included amount. Either 'amount' or 'tiers' is required.",
+    "Tiered pricing.  Either 'amount' or 'tiers' is required.",
     }),
     tier_behavior: z.union([z.literal("graduated"), z.literal("volume")]).optional(),
     
@@ -245,7 +245,7 @@ type PriceWithAmount = PriceBaseFields & {
   tiers?: never;
 };
 
-// Price with graduated tiered pricing (no flat amount per tier)
+// Price with graduated tiered pricing (each tier's rate applies only to units within that tier)
 type PriceWithGraduatedTiers = PriceBaseFields & {
   /** Cannot have flat amount when using tiers */
   amount?: never;
@@ -255,14 +255,19 @@ type PriceWithGraduatedTiers = PriceBaseFields & {
   tierBehavior: "graduated";
 };
 
-// Price with volume tiered pricing (flat amount per tier)
+// Volume tier: at least one of amount or flatAmount must be present
+type VolumeTier =
+  | { to: number | "inf"; amount: number; flatAmount?: number }
+  | { to: number | "inf"; amount?: number; flatAmount: number };
+
+// Price with volume tiered pricing (the tier the total usage falls into applies to all units)
 type PriceWithVolumeTiers = Omit<PriceBaseFields, "billingMethod"> & {
   /** Volume pricing does not support usage_based billing — use 'prepaid' */
   billingMethod: Exclude<BillingMethod, "usage_based">;
   /** Cannot have flat amount when using tiers */
   amount?: never;
   /** Volume tiered pricing: the tier the total usage falls into applies to all units */
-  tiers: Array<{ to: number | "inf"; amount: number; flatAmount?: number }>;
+  tiers: Array<VolumeTier>;
   /** Volume: the rate of the tier the total usage falls into applies to all units */
   tierBehavior: "volume";
 };
diff --git a/typegen/genUtils/TypeGenerator.ts b/typegen/genUtils/TypeGenerator.ts
index 0c06e05e..98da3ffa 100644
--- a/typegen/genUtils/TypeGenerator.ts
+++ b/typegen/genUtils/TypeGenerator.ts
@@ -284,6 +284,7 @@ ${imports}
       OnDecrease: ['prorate', 'refund_immediately', 'no_action'],
       FreeTrialDuration: ['day', 'month', 'year'],
       TierBehaviours: ['graduated', 'volume'],
+      TierBehavior: ['graduated', 'volume'],
       ApiFeatureType: ['static', 'boolean', 'single_use', 'continuous_use', 'credit_system'],
       FeatureType: ['boolean', 'metered', 'credit_system'],
     };
diff --git a/typegen/genUtils/atmnTypeHelpers.ts b/typegen/genUtils/atmnTypeHelpers.ts
index 0b35e964..34ba5125 100644
--- a/typegen/genUtils/atmnTypeHelpers.ts
+++ b/typegen/genUtils/atmnTypeHelpers.ts
@@ -234,16 +234,35 @@ type PriceWithAmount = PriceBaseFields & {
   tiers?: never;
 };
 
-// Price with tiered pricing (no flat amount)
-type PriceWithTiers = PriceBaseFields & {
+// Price with graduated tiered pricing (each tier's rate applies only to units within that tier)
+type PriceWithGraduatedTiers = PriceBaseFields & {
   /** Cannot have flat amount when using tiers */
   amount?: never;
-  /** Tiered pricing structure based on usage ranges */
+  /** Graduated tiered pricing: each tier's amount applies only to units within that tier */
   tiers: Array<{ to: number | "inf"; amount: number }>;
-  /** Required when tiers is defined: how tiers are applied */
-  tierBehaviour: "graduated" | "volume";
+  /** Graduated: each tier's rate applies only to usage within that tier */
+  tierBehavior: "graduated";
 };
 
+// Volume tier: at least one of amount or flatAmount must be present
+type VolumeTier =
+  | { to: number | "inf"; amount: number; flatAmount?: number }
+  | { to: number | "inf"; amount?: number; flatAmount: number };
+
+// Price with volume tiered pricing (the tier the total usage falls into applies to all units)
+type PriceWithVolumeTiers = Omit<PriceBaseFields, "billingMethod"> & {
+  /** Volume pricing does not support usage_based billing — use 'prepaid' */
+  billingMethod: Exclude<BillingMethod, "usage_based">;
+  /** Cannot have flat amount when using tiers */
+  amount?: never;
+  /** Volume tiered pricing: the tier the total usage falls into applies to all units */
+  tiers: Array<VolumeTier>;
+  /** Volume: the rate of the tier the total usage falls into applies to all units */
+  tierBehavior: "volume";
+};
+
+type PriceWithTiers = PriceWithGraduatedTiers | PriceWithVolumeTiers;
+
 // Price must have either amount OR tiers (not both, not neither)
 type PriceAmountOrTiers = PriceWithAmount | PriceWithTiers;