diff --git a/packages/ai/CHANGELOG.md b/packages/ai/CHANGELOG.md
index 65478df6..8f24f4d3 100644
--- a/packages/ai/CHANGELOG.md
+++ b/packages/ai/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed OpenAI-compatible provider feature detection to use `model.provider` in addition to URL, allowing custom base URLs (e.g., proxies) to work correctly with provider-specific settings ([#774](https://github.com/badlogic/pi-mono/issues/774))
+
 ## [0.47.0] - 2026-01-16
 
 ### Fixed
diff --git a/packages/ai/src/providers/openai-completions.ts b/packages/ai/src/providers/openai-completions.ts
index 3edeca45..d194d7ab 100644
--- a/packages/ai/src/providers/openai-completions.ts
+++ b/packages/ai/src/providers/openai-completions.ts
@@ -679,25 +679,33 @@ function mapStopReason(reason: ChatCompletionChunk.Choice["finish_reason"]): Sto
 }
 
 /**
- * Detect compatibility settings from baseUrl for known providers.
+ * Detect compatibility settings from provider and baseUrl for known providers.
+ * Provider takes precedence over URL-based detection since it's explicitly configured.
  * Returns a fully resolved OpenAICompat object with all fields set.
  */
-function detectCompatFromUrl(baseUrl: string): Required<OpenAICompat> {
-	const isZai = baseUrl.includes("api.z.ai");
+function detectCompat(model: Model<"openai-completions">): Required<OpenAICompat> {
+	const provider = model.provider;
+	const baseUrl = model.baseUrl;
+
+	const isZai = provider === "zai" || baseUrl.includes("api.z.ai");
 
 	const isNonStandard =
+		provider === "cerebras" ||
 		baseUrl.includes("cerebras.ai") ||
+		provider === "xai" ||
 		baseUrl.includes("api.x.ai") ||
+		provider === "mistral" ||
 		baseUrl.includes("mistral.ai") ||
 		baseUrl.includes("chutes.ai") ||
 		isZai ||
+		provider === "opencode" ||
 		baseUrl.includes("opencode.ai");
 
-	const useMaxTokens = baseUrl.includes("mistral.ai") || baseUrl.includes("chutes.ai");
+	const useMaxTokens = provider === "mistral" || baseUrl.includes("mistral.ai") || baseUrl.includes("chutes.ai");
 
-	const isGrok = baseUrl.includes("api.x.ai");
+	const isGrok = provider === "xai" || baseUrl.includes("api.x.ai");
 
-	const isMistral = baseUrl.includes("mistral.ai");
+	const isMistral = provider === "mistral" || baseUrl.includes("mistral.ai");
 
 	return {
 		supportsStore: !isNonStandard,
@@ -715,10 +723,10 @@ function detectCompatFromUrl(baseUrl: string): Required<OpenAICompat> {
 
 /**
  * Get resolved compatibility settings for a model.
- * Uses explicit model.compat if provided, otherwise auto-detects from URL.
+ * Uses explicit model.compat if provided, otherwise auto-detects from provider/URL.
  */
 function getCompat(model: Model<"openai-completions">): Required<OpenAICompat> {
-	const detected = detectCompatFromUrl(model.baseUrl);
+	const detected = detectCompat(model);
 	if (!model.compat) return detected;
 
 	return {