fix: OpenAI-compatible provider improvements (system messages, image support, stream interruption)

packages/opencode/src/provider/provider.ts

@@ -845,6 +845,7 @@ const ProviderCapabilities = Schema.Struct({
   input: ProviderModalities,
   output: ProviderModalities,
   interleaved: ProviderInterleaved,
+  systemMessage: Schema.optional(Schema.Union([Schema.Literal("single"), Schema.Literal("multiple")])),
 })
 
 const ProviderCacheCost = Schema.Struct({
@@ -1007,6 +1008,7 @@ function fromModelsDevModel(provider: ModelsDev.Provider, model: ModelsDev.Model
         pdf: model.modalities?.output?.includes("pdf") ?? false,
       },
       interleaved: model.interleaved ?? false,
+      systemMessage: undefined,
     },
     release_date: model.release_date ?? "",
     variants: {},
@@ -1163,12 +1165,15 @@ const layer: Layer.Layer<
                 input: {
                   text: model.modalities?.input?.includes("text") ?? existingModel?.capabilities.input.text ?? true,
                   audio: model.modalities?.input?.includes("audio") ?? existingModel?.capabilities.input.audio ?? false,
-                  image: model.modalities?.input?.includes("image") ?? existingModel?.capabilities.input.image ?? false,
+                  image:
+                    model.modalities?.input?.includes("image") ??
+                    existingModel?.capabilities.input.image ??
+                    (provider.npm === "@ai-sdk/openai-compatible" ? true : false),
                   video: model.modalities?.input?.includes("video") ?? existingModel?.capabilities.input.video ?? false,
                   pdf: model.modalities?.input?.includes("pdf") ?? existingModel?.capabilities.input.pdf ?? false,
                 },
                 output: {
-                  text: model.modalities?.output?.includes("text") ?? existingModel?.capabilities.output.text ?? true,
+                  text: model.modalities?.output?.includes("text") ?? true,
                   audio:
                     model.modalities?.output?.includes("audio") ?? existingModel?.capabilities.output.audio ?? false,
                   image:
@@ -1178,6 +1183,7 @@ const layer: Layer.Layer<
                   pdf: model.modalities?.output?.includes("pdf") ?? existingModel?.capabilities.output.pdf ?? false,
                 },
                 interleaved: model.interleaved ?? false,
+                systemMessage: undefined,
               },
               cost: {
                 input: model?.cost?.input ?? existingModel?.cost?.input ?? 0,

packages/opencode/src/provider/sdk/copilot/chat/convert-to-openai-compatible-chat-messages.ts

@@ -12,15 +12,35 @@ function getOpenAIMetadata(message: { providerOptions?: SharedV3ProviderOptions
 
 export function convertToOpenAICompatibleChatMessages(prompt: LanguageModelV3Prompt): OpenAICompatibleChatPrompt {
   const messages: OpenAICompatibleChatPrompt = []
+
+  const systemPrompt: string[] = []
+  for (const { role, content } of prompt) {
+    if (role === "system") {
+      systemPrompt.push(content)
+    }
+  }
+
+  const hasSystem = systemPrompt.length > 0
+  const hasOthers = prompt.some((m) => m.role !== "system")
+
+  if (hasSystem) {
+    if (hasOthers) {
+      messages.push({
+        role: "system",
+        content: systemPrompt.join("\n\n"),
+      })
+    } else {
+      messages.push({
+        role: "user",
+        content: systemPrompt.join("\n\n"),
+      })
+    }
+  }
+
   for (const { role, content, ...message } of prompt) {
     const metadata = getOpenAIMetadata({ ...message })
     switch (role) {
       case "system": {
-        messages.push({
-          role: "system",
-          content: content,
-          ...metadata,
-        })
         break
       }
 

packages/opencode/src/provider/sdk/copilot/chat/openai-compatible-chat-language-model.ts

@@ -226,8 +226,8 @@ export class OpenAICompatibleChatLanguageModel implements LanguageModelV3 {
       })
     }
 
-    // reasoning content (Copilot uses reasoning_text):
-    const reasoning = choice.message.reasoning_text
+    // reasoning content (Copilot uses reasoning_text, DeepSeek/oMLX uses reasoning_content):
+    const reasoning = choice.message.reasoning_text ?? choice.message.reasoning_content
     if (reasoning != null && reasoning.length > 0) {
       content.push({
         type: "reasoning",
@@ -477,8 +477,8 @@ export class OpenAICompatibleChatLanguageModel implements LanguageModelV3 {
               reasoningOpaque = delta.reasoning_opaque
             }
 
-            // enqueue reasoning before text deltas (Copilot uses reasoning_text):
-            const reasoningContent = delta.reasoning_text
+            // enqueue reasoning before text deltas (Copilot uses reasoning_text, DeepSeek/oMLX uses reasoning_content):
+            const reasoningContent = delta.reasoning_text ?? delta.reasoning_content
             if (reasoningContent) {
               if (!isActiveReasoning) {
                 controller.enqueue({
@@ -645,6 +645,15 @@ export class OpenAICompatibleChatLanguageModel implements LanguageModelV3 {
           },
 
           flush(controller) {
+            // If the stream ended without a finish_reason and output is still
+            // active, the stream was truncated — emit an error to trigger retry
+            const hasActiveOutput = isActiveReasoning || isActiveText || toolCalls.some((tc) => !tc.hasFinished)
+            if (finishReason.unified === "other" && finishReason.raw === undefined && hasActiveOutput) {
+              controller.enqueue({
+                type: "error",
+                error: new Error("Stream ended unexpectedly — no finish reason received while output was still active"),
+              })
+            }
             if (isActiveReasoning) {
               controller.enqueue({
                 type: "reasoning-end",
@@ -757,6 +766,7 @@ const OpenAICompatibleChatResponseSchema = z.object({
         // Copilot-specific reasoning fields
         reasoning_text: z.string().nullish(),
         reasoning_opaque: z.string().nullish(),
+        reasoning_content: z.string().nullish(),
         tool_calls: z
           .array(
             z.object({
@@ -792,6 +802,7 @@ const createOpenAICompatibleChatChunkSchema = <ERROR_SCHEMA extends z.core.$ZodT
               // Copilot-specific reasoning fields
               reasoning_text: z.string().nullish(),
               reasoning_opaque: z.string().nullish(),
+              reasoning_content: z.string().nullish(),
               tool_calls: z
                 .array(
                   z.object({

packages/opencode/src/session/llm.ts

@@ -29,6 +29,23 @@ const log = Log.create({ service: "llm" })
 export const OUTPUT_TOKEN_MAX = ProviderTransform.OUTPUT_TOKEN_MAX
 type Result = Awaited<ReturnType<typeof streamText>>
 
+function getSystemMessageMode(model: Provider.Model): "single" | "multiple" {
+  if (model.capabilities.systemMessage) {
+    return model.capabilities.systemMessage
+  }
+  const providerDefaults: Record<string, "single" | "multiple"> = {
+    anthropic: "multiple",
+  }
+  const mode = providerDefaults[model.providerID] ?? "single"
+  if (!providerDefaults[model.providerID]) {
+    log.info("Using default 'single' systemMessage mode for provider", {
+      providerID: model.providerID,
+      modelID: model.id,
+    })
+  }
+  return mode
+}
+
 export type StreamInput = {
   user: MessageV2.User
   sessionID: string
@@ -150,12 +167,14 @@ const live: Layer.Layer<
         : isWorkflow
           ? input.messages
           : [
-              ...system.map(
-                (x): ModelMessage => ({
-                  role: "system",
-                  content: x,
-                }),
-              ),
+              ...(getSystemMessageMode(input.model) === "multiple"
+                ? system.map(
+                    (x): ModelMessage => ({
+                      role: "system",
+                      content: x,
+                    }),
+                  )
+                : ([{ role: "system", content: system.join("\n") }] as ModelMessage[])),
               ...input.messages,
             ]
 

packages/opencode/src/session/message-v2.ts

@@ -1028,6 +1028,15 @@ export function fromError(
         },
         { cause: e },
       ).toObject()
+    case e instanceof Error && e.message === "SSE read timed out":
+      return new APIError(
+        {
+          message: "Stream read timed out — no data received within the chunk timeout window",
+          isRetryable: true,
+          metadata: { code: "SSE_TIMEOUT", message: e.message },
+        },
+        { cause: e },
+      ).toObject()
     case e instanceof Error:
       return new NamedError.Unknown({ message: errorMessage(e) }, { cause: e }).toObject()
     default:

packages/opencode/src/session/retry.ts

@@ -63,14 +63,18 @@ export function retryable(error: Err) {
     return error.data.message.includes("Overloaded") ? "Provider is overloaded" : error.data.message
   }
 
-  // Check for rate limit patterns in plain text error messages
+  // Check for stream interruption and rate limit patterns in plain text error messages
   const msg = error.data?.message
   if (typeof msg === "string") {
     const lower = msg.toLowerCase()
     if (
       lower.includes("rate increased too quickly") ||
       lower.includes("rate limit") ||
-      lower.includes("too many requests")
+      lower.includes("too many requests") ||
+      lower.includes("sse read timed out") ||
+      lower.includes("connection reset") ||
+      lower.includes("aborted") ||
+      lower.includes("stream ended unexpectedly")
     ) {
       return msg
     }