Files
langgraph/libs
Sydney RunkleandClaude Sonnet 4.6 7cd2e3fe1a fix(channels): address code review feedback on DeltaChannel
delta.py — value consistency:
- `__init__` now starts with `value=MISSING` (was `[]`); both fresh
  construction and clones are consistently uninitialised until
  `from_checkpoint()` or `copy()` sets the real value
- `_clone_empty` drops `__new__` in favour of the normal constructor;
  `typ` and `key` are restored explicitly afterwards (`typ` may differ
  from `list` when set via Annotated injection; `key` is injected by
  the graph builder after construction)

delta.py — snapshot cadence:
- `is_snapshot_step` now guards `step > 0`; snapshots fire at steps N,
  2N, 3N, … instead of also at step 0 where `0 % N == 0` always held

_checkpoint.py — runtime guards:
- replace both `assert isinstance(spec, DeltaChannel)` with proper
  `if not isinstance: raise TypeError`; `assert` is stripped by `-O`
  and is wrong for production invariant checks

binop.py — avoid unnecessary allocation:
- `_get_overwrite`: replace `set(value.keys()) == {OVERWRITE}` with
  `len(value) == 1 and OVERWRITE in value` to avoid allocating a
  throwaway set on every call

checkpoint-postgres — typed rows:
- add `_DeltaCombinedRow(TypedDict, total=False)` documenting the nine
  columns emitted by `SELECT_DELTA_COMBINED_SQL`'s UNION ALL; change
  `_build_delta_channel_writes_history` parameter from `Sequence[Any]`
  to `Sequence[_DeltaCombinedRow]`; call sites cast the psycopg
  `DictRow` result accordingly

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>
2026-04-30 14:49:05 -04:00
..