fix(opencode): surface content-filter finish reason as visible error (#31745)

Co-authored-by: Aiden Cline <aidenpcline@gmail.com>

packages/opencode/src/session/prompt.ts

@@ -1355,6 +1355,18 @@ export const layer = Layer.effect(
 
             const finished = handle.message.finish && !["tool-calls", "unknown"].includes(handle.message.finish)
             if (finished && !handle.message.error) {
+              // Surface any content-filter finish (e.g. Anthropic stop_reason:
+              // refusal) as an error. These turns may have produced no visible
+              // output at all — previously the session went idle silently — or
+              // partial text that was cut off by the provider's filter.
+              if (handle.message.finish === "content-filter") {
+                handle.message.error = new SessionV1.ContentFilterError({
+                  message: "The response was blocked by the provider's content filter",
+                }).toObject()
+                yield* sessions.updateMessage(handle.message)
+                yield* events.publish(Session.Event.Error, { sessionID, error: handle.message.error })
+                return "break" as const
+              }
               if (format.type === "json_schema") {
                 handle.message.error = new SessionV1.StructuredOutputError({
                   message: "Model did not produce structured output",