Changelog

Unreleased

Changes since v4.11.0.

Changes since v4.10.0.

Add LLM::Stream for richer streaming callbacks, including on_content, on_reasoning_content, and on_tool_call for concurrent tool execution.
Add LLM::Stream#wait as a shortcut for queue.wait.
Add LLM::Context#wait as a shortcut for the configured stream's wait.
Add LLM::Context#call(:functions) as a shortcut for functions.call.
Add LLM::Function.registry and enhanced support for MCP tools in LLM::Tool.registry for tool resolution during streaming.
Add normalized LLM::Response for OpenAI Responses, providing content, content!, messages / choices, usage, and reasoning_content.
Add mode: :responses to LLM::Context for routing talk through the Responses API.
Add LLM::Context#returns for collecting pending tool returns from the context.
Add persistent HTTP connection pooling for repeated MCP tool calls via LLM.mcp(http: ...).persist!.
Add explicit MCP transport constructors via LLM::MCP.stdio(...) and LLM::MCP.http(...).

Fix Google tool-call handling by synthesizing stable ids when Gemini does not provide a direct tool-call id.

Changes since v4.9.0.

Add HTTP transport for MCP with LLM::MCP::Transport::HTTP for remote servers
Add JSON Schema union types (any_of, all_of, one_of) with parser integration
Add JSON Schema type array union support (e.g., "type": ["object", "null"])
Add JSON Schema type inference from const, enum, or default fields

Changes since v4.8.0.

Add fiber-based concurrency with LLM::Function::FiberGroup and LLM::Function::TaskGroup classes for lightweight async execution.
Add :thread, :task, and :fiber strategy parameter to LLM::Function#spawn for explicit concurrency control.
Add stdio MCP client support, including remote tool discovery and invocation through LLM.mcp, LLM::Context, and existing function/tool APIs.
Add model registry support via LLM::Registry, including model metadata lookup, pricing, modalities, limits, and cost estimation.
Add context access to a model context window via LLM::Context#context_window.
Add tracking of defined tools in the tool registry.
Add LLM::Schema::Enum, enabling Enum[...] as a schema/tool parameter type.
Add top-level Anthropic system instruction support using Anthropic's provider-specific request format.
Add richer tracing hooks and extra metadata support for LangSmith/OpenTelemetry-style traces.
Add rack/websocket and Relay-related example work, including MCP-focused examples.
Add concurrent tool execution with LLM::Function#spawn, LLM::Function::Array (call, wait, spawn), and LLM::Function::ThreadGroup.
Add LLM::Function::ThreadGroup#alive? method for non-blocking monitoring of concurrent tool execution.
Add LLM::Function::ThreadGroup#value alias for ThreadGroup#wait for consistency with Ruby's Thread#value.

Rename LLM::Session to LLM::Context throughout the codebase to better reflect the concept of a stateful interaction environment.
Rename LLM::Gemini to LLM::Google to better reflect provider naming.
Standardize model objects across providers around a smaller common interface.
Switch registry cost internals from LLM::Estimate to LLM::Cost.
Update image generation defaults so OpenAI and xAI consistently return base64-encoded image data by default.
Update LLM::Bot deprecation warning from v5.0 to v6.0, giving users more time to migrate to LLM::Context.
Rework the README and screencast documentation to better cover MCP, registry, contexts, prompts, concurrency, providers, and example flow.
Expand the README with architecture, production, and provider guidance while improving readability and example ordering.

Fix local schema $ref resolution in LLM::Schema::Parser.
Fix multiple MCP issues around stdio env handling, request IDs, registry interaction, tool registration, and filtering of MCP tools from the standard tool registry.
Fix stream parsing issues, including chunk-splitting bugs and safer handling of streamed error responses.
Fix prompt handling across contexts, agents, and provider adapters so prompt turns remain consistent in history and completions.
Fix several tool/context issues, including function return wrapping, tool lookup after deserialization, unnamed subclass filtering, and thread-safety around tool registry mutations.
Fix Google tool-call handling to preserve thoughtSignature.
Fix LLM::Tracer::Logger argument handling.
Fix packaging/docs issues such as registry files in the gemspec and stale provider docs.
Fix Google provider handling of nil function IDs during context deserialization.
Fix MCP stdio transport by increasing poll timeout for better reliability.
Fix Google provider to properly cast non-Hash tool results into Hash format for API compatibility.
Fix schema parser to support recursive normalization of Array, LLM::Object, and nested structures.
Fix DeepSeek provider to tolerate malformed tool arguments.
Fix LLM::Function::TaskGroup#alive? to properly delegate to Async::Task#alive?.
Fix various RuboCop errors across the codebase.
Fix DeepSeek provider to handle JSON that might be valid but unexpected.

Notable merged work in this range includes:

Comparison base: