diff --git a/packages/opencode/src/session/llm.ts b/packages/opencode/src/session/llm.ts
index a8009c49d..a22c6d856 100644
--- a/packages/opencode/src/session/llm.ts
+++ b/packages/opencode/src/session/llm.ts
@@ -250,12 +250,16 @@ export namespace LLM {
       maxOutputTokens,
       abortSignal: input.abort,
       headers: {
-        ...(input.model.providerID.startsWith("opencode") && {
-          "x-opencode-project": Instance.project.id,
-          "x-opencode-session": input.sessionID,
-          "x-opencode-request": input.user.id,
-          "x-opencode-client": Flag.OPENCODE_CLIENT,
-        }),
+        ...(input.model.providerID.startsWith("opencode")
+          ? {
+              "x-opencode-project": Instance.project.id,
+              "x-opencode-session": input.sessionID,
+              "x-opencode-request": input.user.id,
+              "x-opencode-client": Flag.OPENCODE_CLIENT,
+            }
+          : {
+              "User-Agent": `opencode/${Installation.VERSION}`,
+            }),
         ...input.model.headers,
         ...headers,
       },