diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index aae42a77f6..f0a47d8b0e 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -227,10 +227,10 @@ function normalizeMessages(
     })
   }
 
+  const modelID = model.api.id.toLowerCase()
   if (
     model.providerID === "mistral" ||
-    model.api.id.toLowerCase().includes("mistral") ||
-    model.api.id.toLowerCase().includes("devstral")
+    ["mistral", "devstral", "codestral", "pixtral", "mixtral"].some((family) => modelID.includes(family))
   ) {
     const scrub = (id: string) => {
       return id
diff --git a/packages/opencode/test/provider/transform.test.ts b/packages/opencode/test/provider/transform.test.ts
index 79733f37a0..0c478ad812 100644
--- a/packages/opencode/test/provider/transform.test.ts
+++ b/packages/opencode/test/provider/transform.test.ts
@@ -1672,6 +1672,55 @@ describe("ProviderTransform.schema - moonshot $ref siblings", () => {
   })
 })
 
+describe("ProviderTransform.message - Mistral tool call IDs", () => {
+  test.each(["codestral-latest", "pixtral-large-latest", "open-mixtral-8x22b"])(
+    "normalizes IDs for custom OpenAI-compatible %s models",
+    (id) => {
+      const result = ProviderTransform.message(
+        [
+          {
+            role: "assistant",
+            content: [
+              {
+                type: "tool-call",
+                toolCallId: "toolu_01CBhTTz95qkd9LJMdC9sf8t",
+                toolName: "read",
+                input: { filePath: "/tmp/test" },
+              },
+            ],
+          },
+          {
+            role: "tool",
+            content: [
+              {
+                type: "tool-result",
+                toolCallId: "toolu_01CBhTTz95qkd9LJMdC9sf8t",
+                toolName: "read",
+                output: { type: "text", value: "test" },
+              },
+            ],
+          },
+        ] as any,
+        {
+          id: `custom/${id}`,
+          providerID: "custom",
+          api: {
+            id,
+            url: "https://example.com/v1",
+            npm: "@ai-sdk/openai-compatible",
+          },
+        } as any,
+        {},
+      )
+
+      expect(result).toMatchObject([
+        { role: "assistant", content: [{ type: "tool-call", toolCallId: "toolu01CB" }] },
+        { role: "tool", content: [{ type: "tool-result", toolCallId: "toolu01CB" }] },
+      ])
+    },
+  )
+})
+
 describe("ProviderTransform.message - DeepSeek reasoning content", () => {
   test("DeepSeek with tool calls includes reasoning_content in providerOptions", () => {
     const msgs = [