diff --git a/.changeset/kupmios-ogmios-params-variants.md b/.changeset/kupmios-ogmios-params-variants.md
new file mode 100644
index 00000000..d394f40a
--- /dev/null
+++ b/.changeset/kupmios-ogmios-params-variants.md
@@ -0,0 +1,5 @@
+---
+"@evolution-sdk/evolution": patch
+---
+
+The Kupmios provider's `getProtocolParameters` no longer fails against Ogmios servers whose protocol-parameter reply differs from the preprod shape it was written against. The Ogmios schema makes each `plutusCostModels` language optional — Ogmios builds that map from the cost models that exist on the network, so a language with no cost model is omitted entirely — and a missing language now maps to an empty cost model instead of failing the whole call (#568). The schema also accepts the Ogmios v7 spelling of the reference-script size limit: `maxReferenceScriptsSize` was renamed to `maxReferenceScriptsSizePerTransaction` (with a new `maxReferenceScriptsSizePerBlock` alongside), so all three keys are optional and either server generation decodes (#559).
diff --git a/packages/evolution/src/sdk/provider/internal/KupmiosEffects.ts b/packages/evolution/src/sdk/provider/internal/KupmiosEffects.ts
index 7b1f5094..d0af272c 100644
--- a/packages/evolution/src/sdk/provider/internal/KupmiosEffects.ts
+++ b/packages/evolution/src/sdk/provider/internal/KupmiosEffects.ts
@@ -61,14 +61,15 @@ const toProtocolParameters = (result: Ogmios.ProtocolParameters): Provider.Proto
     maxCollateralInputs: Number(result.maxCollateralInputs),
     minFeeRefScriptCostPerByte: result.minFeeReferenceScripts.base,
     costModels: {
+      // A language Ogmios omitted has no cost model on this network: {}
       PlutusV1: Object.fromEntries(
-        result.plutusCostModels["plutus:v1"].map((value, index) => [index.toString(), Number(value)])
+        (result.plutusCostModels["plutus:v1"] ?? []).map((value, index) => [index.toString(), Number(value)])
       ),
       PlutusV2: Object.fromEntries(
-        result.plutusCostModels["plutus:v2"].map((value, index) => [index.toString(), Number(value)])
+        (result.plutusCostModels["plutus:v2"] ?? []).map((value, index) => [index.toString(), Number(value)])
       ),
       PlutusV3: Object.fromEntries(
-        result.plutusCostModels["plutus:v3"].map((value, index) => [index.toString(), Number(value)])
+        (result.plutusCostModels["plutus:v3"] ?? []).map((value, index) => [index.toString(), Number(value)])
       )
     }
   }
diff --git a/packages/evolution/src/sdk/provider/internal/Ogmios.ts b/packages/evolution/src/sdk/provider/internal/Ogmios.ts
index 71ced59d..017934d2 100644
--- a/packages/evolution/src/sdk/provider/internal/Ogmios.ts
+++ b/packages/evolution/src/sdk/provider/internal/Ogmios.ts
@@ -35,9 +35,25 @@ export const ProtocolParametersSchema = Schema.Struct({
     range: Schema.BigInt,
     multiplier: Schema.NumberFromString
   }),
-  maxReferenceScriptsSize: Schema.Struct({
-    bytes: Schema.BigInt
-  }),
+  // Ogmios v7 renamed this to maxReferenceScriptsSizePerTransaction and
+  // added maxReferenceScriptsSizePerBlock; deployed servers run both major
+  // versions, so every spelling is optional (the value is not mapped into
+  // the provider's ProtocolParameters).
+  maxReferenceScriptsSize: Schema.optional(
+    Schema.Struct({
+      bytes: Schema.BigInt
+    })
+  ),
+  maxReferenceScriptsSizePerTransaction: Schema.optional(
+    Schema.Struct({
+      bytes: Schema.BigInt
+    })
+  ),
+  maxReferenceScriptsSizePerBlock: Schema.optional(
+    Schema.Struct({
+      bytes: Schema.BigInt
+    })
+  ),
   stakePoolVotingThresholds: Schema.Struct({
     noConfidence: TupleNumberFromString,
     constitutionalCommittee: Schema.Struct({
@@ -89,10 +105,12 @@ export const ProtocolParametersSchema = Schema.Struct({
   minStakePoolCost: Schema.Struct({ ada: LovelaceAsset }),
   minUtxoDepositConstant: Schema.Struct({ ada: LovelaceAsset }),
   minUtxoDepositCoefficient: Schema.BigInt,
+  // Ogmios builds this map from the cost models that exist on the network,
+  // so a language with no cost model is omitted entirely, not sent empty.
   plutusCostModels: Schema.Struct({
-    "plutus:v1": Schema.Array(Schema.BigInt),
-    "plutus:v2": Schema.Array(Schema.BigInt),
-    "plutus:v3": Schema.Array(Schema.BigInt)
+    "plutus:v1": Schema.optional(Schema.Array(Schema.BigInt)),
+    "plutus:v2": Schema.optional(Schema.Array(Schema.BigInt)),
+    "plutus:v3": Schema.optional(Schema.Array(Schema.BigInt))
   }),
   scriptExecutionPrices: Schema.Struct({
     memory: TupleNumberFromString,
diff --git a/packages/evolution/test/provider/Kupmios.test.ts b/packages/evolution/test/provider/Kupmios.test.ts
index 264cf92c..27f6662e 100644
--- a/packages/evolution/test/provider/Kupmios.test.ts
+++ b/packages/evolution/test/provider/Kupmios.test.ts
@@ -129,6 +129,52 @@ describe("Kupmios read paths", () => {
     expect(Object.values(params.costModels.PlutusV3)).toEqual(expected.plutusCostModels["plutus:v3"])
   })
 
+  it("getProtocolParameters with an Ogmios cost model language missing (#568)", async () => {
+    // Ogmios builds plutusCostModels from costModelsValid, so a network
+    // without a Plutus V1 cost model omits the "plutus:v1" key entirely.
+    const withoutV1 = protocolParameters.replace(/"plutus:v1": \[[^\]]*\],\s*/, "")
+    expect(withoutV1).not.toContain('"plutus:v1"')
+    stubKupmios({ ogmios: { "queryLedgerState/protocolParameters": withoutV1 } })
+    const { result: expected } = JSON.parse(withoutV1)
+
+    const params = await Effect.runPromise(KupmiosEffects.getProtocolParametersEffect(OGMIOS_URL))
+
+    // A missing language maps to an empty cost model; the others are intact
+    expect(params.costModels.PlutusV1).toEqual({})
+    expect(Object.values(params.costModels.PlutusV2)).toEqual(expected.plutusCostModels["plutus:v2"])
+    expect(Object.values(params.costModels.PlutusV3)).toEqual(expected.plutusCostModels["plutus:v3"])
+    expect(params.minFeeA).toBe(44)
+  })
+
+  it("getProtocolParameters with no Ogmios cost models at all (#568)", async () => {
+    const noModels = protocolParameters.replace(
+      /"plutusCostModels": \{[\s\S]*?\},\s*"scriptExecutionPrices"/,
+      `"plutusCostModels": {},\n    "scriptExecutionPrices"`
+    )
+    expect(JSON.parse(noModels).result.plutusCostModels).toEqual({})
+    stubKupmios({ ogmios: { "queryLedgerState/protocolParameters": noModels } })
+
+    const params = await Effect.runPromise(KupmiosEffects.getProtocolParametersEffect(OGMIOS_URL))
+
+    expect(params.costModels).toEqual({ PlutusV1: {}, PlutusV2: {}, PlutusV3: {} })
+  })
+
+  it("getProtocolParameters against Ogmios v7 (maxReferenceScriptsSize renamed, #559)", async () => {
+    // Ogmios v7 renames maxReferenceScriptsSize to
+    // maxReferenceScriptsSizePerTransaction and adds a PerBlock key.
+    const v7 = protocolParameters.replace(
+      /"maxReferenceScriptsSize": \{\s*"bytes": 204800\s*\}/,
+      `"maxReferenceScriptsSizePerTransaction": {"bytes": 204800},\n    "maxReferenceScriptsSizePerBlock": {"bytes": 1048576}`
+    )
+    expect(v7).toContain('"maxReferenceScriptsSizePerTransaction"')
+    expect(v7).not.toContain('"maxReferenceScriptsSize":')
+    stubKupmios({ ogmios: { "queryLedgerState/protocolParameters": v7 } })
+
+    const params = await Effect.runPromise(KupmiosEffects.getProtocolParametersEffect(OGMIOS_URL))
+
+    expect(params).toMatchObject({ minFeeA: 44, minFeeB: 155381, maxTxSize: 16384 })
+  })
+
   it("getUtxos by address", async () => {
     stubKupmios({ kupo: kupo() })