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    Pythonlanggraph.checkpointbaseDeltaChannelHistory
    Class●Since v4.0

    DeltaChannelHistory

    Copy
    DeltaChannelHistory()

    Bases

    TypedDict

    Constructors

    Attributes

    View source on GitHub
    constructor
    __init__
    NameType
    writeslist[PendingWrite]
    seedNotRequired[Any]
    attribute
    writes: list[PendingWrite]
    attribute
    seed: NotRequired[Any]

    Per-channel result entry from BaseCheckpointSaver.get_delta_channel_history.

    Storage-level view of what one channel contributed across the ancestor chain of a target checkpoint:

    • writes — on-path deltas oldest→newest as PendingWrite tuples. Always present; possibly empty. Already filtered to one channel. Writes stored at the target checkpoint itself are pending for the next super-step and are excluded.
    • seed — the stored value at the nearest ancestor whose channel_values[ch] is populated. Omitted if the walk reached the root without finding any stored value (consumer treats absence as "start empty"). Typically a _DeltaSnapshot for delta channels with finite snapshot frequency, or a plain value for threads migrated from a pre-delta channel type.