From e5b2bb8628b1a2850c6a4e7c987f9c464ee09d3c Mon Sep 17 00:00:00 2001
From: Mark IJbema <mark@kilocode.ai>
Date: Tue, 26 May 2026 10:22:16 +0200
Subject: [PATCH] fix(gateway): preserve FIM gateway model passthrough

---
 packages/kilo-gateway/src/server/fim.ts             |  6 +++++-
 packages/kilo-gateway/test/fim.test.ts              | 13 +++++++++----
 .../server/httpapi/handlers/kilo-gateway.ts         |  6 +++++-
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/packages/kilo-gateway/src/server/fim.ts b/packages/kilo-gateway/src/server/fim.ts
index 58a89eb05a5..d344337941d 100644
--- a/packages/kilo-gateway/src/server/fim.ts
+++ b/packages/kilo-gateway/src/server/fim.ts
@@ -24,6 +24,10 @@ const CODESTRAL_FIM_URL = "https://codestral.mistral.ai/v1/fim/completions"
 const INCEPTION_FIM_URL = "https://api.inceptionlabs.ai/v1/fim/completions"
 
 export function resolveFimTarget(provider?: string, model?: string): FimTarget {
+  if (!provider || provider === "kilo") {
+    return { provider: "kilo", model: model ?? "mistralai/codestral-2501", urls: [KILO_FIM_URL] }
+  }
+
   const info = getAutocompleteModel(provider, model)
   if (info.directProvider === "mistral") {
     return { provider: "mistral", model: info.requestModel, urls: [MISTRAL_FIM_URL, CODESTRAL_FIM_URL] }
@@ -31,7 +35,7 @@ export function resolveFimTarget(provider?: string, model?: string): FimTarget {
   if (info.directProvider === "inception") {
     return { provider: "inception", model: info.requestModel, urls: [INCEPTION_FIM_URL] }
   }
-  return { provider: "kilo", model: info.requestModel, urls: [KILO_FIM_URL] }
+  return { provider: "kilo", model: model ?? "mistralai/codestral-2501", urls: [KILO_FIM_URL] }
 }
 
 async function getProxyAuth(Auth: Auth) {
diff --git a/packages/kilo-gateway/test/fim.test.ts b/packages/kilo-gateway/test/fim.test.ts
index c87e130ad86..e9874638e1d 100644
--- a/packages/kilo-gateway/test/fim.test.ts
+++ b/packages/kilo-gateway/test/fim.test.ts
@@ -28,7 +28,12 @@ describe("FIM target resolution", () => {
     })
   })
 
-  test("maps legacy gateway IDs to explicit Kilo Gateway targets", () => {
+  test("preserves gateway model pass-through behavior", () => {
+    expect(resolveFimTarget()).toEqual({
+      provider: "kilo",
+      model: "mistralai/codestral-2501",
+      urls: ["https://api.kilo.ai/api/fim/completions"],
+    })
     expect(resolveFimTarget(undefined, "mistralai/codestral-2508")).toEqual({
       provider: "kilo",
       model: "mistralai/codestral-2508",
@@ -36,12 +41,12 @@ describe("FIM target resolution", () => {
     })
     expect(resolveFimTarget(undefined, "inception/mercury-edit")).toEqual({
       provider: "kilo",
-      model: "inception/mercury-edit-2",
+      model: "inception/mercury-edit",
       urls: ["https://api.kilo.ai/api/fim/completions"],
     })
-    expect(resolveFimTarget(undefined, "inception/mercury-edit-2")).toEqual({
+    expect(resolveFimTarget("kilo", "custom/fim-model")).toEqual({
       provider: "kilo",
-      model: "inception/mercury-edit-2",
+      model: "custom/fim-model",
       urls: ["https://api.kilo.ai/api/fim/completions"],
     })
   })
diff --git a/packages/opencode/src/kilocode/server/httpapi/handlers/kilo-gateway.ts b/packages/opencode/src/kilocode/server/httpapi/handlers/kilo-gateway.ts
index ced90a89b58..02535ee8a02 100644
--- a/packages/opencode/src/kilocode/server/httpapi/handlers/kilo-gateway.ts
+++ b/packages/opencode/src/kilocode/server/httpapi/handlers/kilo-gateway.ts
@@ -52,6 +52,10 @@ const DIRECT_FIM_ENV: Record<Exclude<FimProvider, "kilo">, string[]> = {
 }
 
 function resolveFimTarget(provider?: string, model?: string) {
+  if (!provider || provider === "kilo") {
+    return { provider: "kilo" as const, model: model ?? "mistralai/codestral-2501", urls: [KILO_FIM_URL] }
+  }
+
   const info = getAutocompleteModel(provider, model)
   if (info.directProvider === "mistral") {
     return { provider: "mistral" as const, model: info.requestModel, urls: [MISTRAL_FIM_URL, CODESTRAL_FIM_URL] }
@@ -59,7 +63,7 @@ function resolveFimTarget(provider?: string, model?: string) {
   if (info.directProvider === "inception") {
     return { provider: "inception" as const, model: info.requestModel, urls: [INCEPTION_FIM_URL] }
   }
-  return { provider: "kilo" as const, model: info.requestModel, urls: [KILO_FIM_URL] }
+  return { provider: "kilo" as const, model: model ?? "mistralai/codestral-2501", urls: [KILO_FIM_URL] }
 }
 
 export const kiloGatewayHandlers = HttpApiBuilder.group(InstanceHttpApi, "kilo", (handlers) =>