langgraph 0.2.5

Summary of Changes

• Added support for preserving task errors in state snapshots, allowing better visibility into failures
• Enhanced state history tracking with proper step numbering and task details
• Simplified the managed values interface by removing the unnecessary task parameter
• Improved error handling during graph execution with better mechanisms to save errors to checkpoints
• Added new error constant for more consistent error tracking across the system

Detailed Changes

langgraph.constants.ERROR

• Added new constant ERROR = "__error__" for tracking and propagating errors in graph execution
• Added the ERROR constant to the RESERVED set of special keys

langgraph.managed.base.ManagedValue

• Simplified interface by removing the task parameter from the __call__ method
• Changed signature from __call__(self, step: int, task: PregelTaskDescription) -> V to __call__(self, step: int) -> V

langgraph.managed.is_last_step.IsLastStepManager

• Updated to match the simplified ManagedValue interface by removing the task parameter
• Changed signature from __call__(self, step: int, task: PregelExecutableTask) to __call__(self, step: int)

langgraph.pregel.types.StateSnapshot

• Enhanced with additional field tasks to include information about tasks with errors
• Added better typing and documentation for fields
• Improved representation of task state in snapshots

langgraph.pregel.types.PregelTask

• Replaced PregelTaskDescription with enhanced PregelTask class
• Added id field to uniquely identify tasks
• Added optional error field to track exceptions that occurred during task execution

langgraph.pregel.algo

• Improved task preparation logic in prepare_next_tasks function
• Made task ID generation more consistent for both execution and non-execution contexts
• Updated managed value handling to use simplified interface without task parameter

langgraph.pregel.debug

• Added tasks_w_writes function to associate tasks with their writes and any errors
• Enhanced checkpoint debug output to include task errors
• Improved visibility of task execution state in debug information

langgraph.pregel.init.Pregel

• Enhanced get_state and aget_state methods to include proper step numbers and task information
• Added tracking of task errors in state snapshots
• Added _exception and _should_stop_others helper functions for better error handling
• Changed error handling in task execution to save errors to the checkpointer
• Fixed debug output to use the passed parameter instead of instance variable

langgraph.pregel.loop.PregelLoop

• Updated to skip ERROR entries when processing pending writes
• Improved handling of error cases in the task execution flow