fix: opencode provider uses system role instead of developer (#755)

* fix: opencode provider uses system role instead of developer for /v1 endpoint

* changelog updated

packages/ai/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed OpenCode provider's `/v1` endpoint to use `system` role instead of `developer` role, fixing `400 Incorrect role information` error for models using `openai-completions` API ([#755](https://github.com/badlogic/pi-mono/pull/755) by [@melihmucuk](https://github.com/melihmucuk))
+
 ## [0.46.0] - 2026-01-15
 
 ### Added

packages/ai/src/providers/openai-completions.ts

@@ -690,7 +690,8 @@ function detectCompatFromUrl(baseUrl: string): Required<OpenAICompat> {
 		baseUrl.includes("api.x.ai") ||
 		baseUrl.includes("mistral.ai") ||
 		baseUrl.includes("chutes.ai") ||
-		isZai;
+		isZai ||
+		baseUrl.includes("opencode.ai");
 
 	const useMaxTokens = baseUrl.includes("mistral.ai") || baseUrl.includes("chutes.ai");