JetBrains/koog 0.6.3 on GitHub

Improvements

Streaming reasoning support: Models with reasoning capabilities (like Claude Sonnet 4.5 or GPT-o1) now stream their reasoning process in real-time, allowing you to see how the model thinks through problems as it generates responses (KG-592, #1264)
LLModel API enhancement: LLM clients now return List<LLModel> instead of List<String> for improved type safety and direct access to model metadata (#1452)
Multiple event handlers per feature: Features can register multiple handlers for the same event type, enabling more flexible event processing (KG-678, #1446)
Dependency updates: Updated Kotlin libraries (KG-544, #1475):
- Kotlin from 2.2.21 to 2.3.10
- kotlinx-serialization from 1.8.1 to 1.10.0
- kotlinx-datetime from 0.6.2 to 0.7.1

OpenRouter streaming: Fixed parsing errors when receiving reasoning content from models with reasoning capabilities by adding missing reasoning and reasoningDetails fields to the streaming response (#854)
ReadFileTool: Fixed incorrect binary file detection for empty files (KG-533, #1340)
DevstralMedium model: Added missing LLMCapability.Document capability (#1482)
Ktor integration: Fixed custom timeout values being ignored when configuring LLM providers in application.yaml (KTOR-8881, #807)

Streaming API redesign: Restructured StreamFrame types to distinguish between delta frames (incremental content like TextDelta, ReasoningDelta) and complete frames (full content like TextComplete, ReasoningComplete). Added End frame type to signal stream completion (#1264)
Kotlin version update: Migrated from Kotlin 2.2.21 to 2.3.10; replaced kotlinx.datetime.Clock/Instant with kotlin.time.Clock/Instant (#1475)
LLModel API changes: LLMClient.models() now returns List<LLModel> instead of List<String>; LLModel.capabilities and LLModel.contextLength are now nullable (#1452)

Updated documentation for the singleRunStrategy API and AIAgentService class.

Module restructuring: Moved file-system abstractions (GlobPattern, FileSize, FileSystemEntry, FileSystemEntryBuilders) from agents-ext to rag-base module to reduce transitive dependencies (#1278)