Follow-up to #8540, which turned on `PLC0415` (import-outside-top-level)
for checkpoint-postgres and checkpoint-sqlite. This does the remaining
six packages: checkpoint, checkpoint-conformance, langgraph, prebuilt,
cli, sdk-py.
Scoped to tests, per @sydney-runkle's call on #8540: library code is
exempted with `per-file-ignores`, since it still has deferred imports
nobody has reviewed and mixing that in would make this hard to read.
## What changed
Function-level imports across 56 test files moved to module level. Nine
could not move and carry an explicit `# noqa: PLC0415` with a reason:
| File | Why it stays local |
|---|---|
| `libs/langgraph/tests/test_deprecation.py` (4) | the import has to run
inside `pytest.warns` for the warning to be observed |
| `libs/langgraph/tests/test_serde_allowlist.py` | try/except guard,
skips when langchain_core is absent |
| `libs/langgraph/tests/test_delta_channel_benchmark.py` | optional
psycopg probe |
| `libs/checkpoint/tests/test_conformance_delta.py` (3) | protected by a
module-level `pytest.importorskip`; hoisting past the guard turns a skip
into a collection error |
That last one is the trap: an import moved above `pytest.importorskip`
silently defeats the guard. I hit it locally and it turned the skip into
a `ModuleNotFoundError` at collection. Every file with an `importorskip`
or `except ImportError` was checked by hand for this.
## Verification
`make lint` and `make test` in each of the six:
| Package | Tests |
|---|---|
| checkpoint | 156 passed, 17 skipped |
| checkpoint-conformance | 1 passed |
| langgraph | 1968 passed, 4 skipped |
| prebuilt | 284 passed |
| cli | 336 passed |
| sdk-py | 493 passed |
Also confirmed the rule actually fires: a throwaway test file with a
function-level import is flagged in all six packages, and the source
exemption holds.
Follow-up to review on #8540, where a stale `# noqa: E402` slipped past
me and Sydney spotted it by eye. This turns on the rule that catches
that automatically.
`RUF100` flags a `noqa` that suppresses nothing. `sdk-py` already had it
through its blanket `RUF` selection; this adds it to the other seven
packages and clears what it finds.
### The 33 it flags, all autofixed
**Blanket `# noqa` on docstring-closing lines** (4, in
`checkpoint-postgres` and `checkpoint-sqlite`). `E501` is in
`lint.ignore` for those packages, so nothing was being suppressed:
```diff
- """ # noqa
+ """
```
**`# noqa: F821` on `anext(aiter_)`** (2). Left over from Python 3.9
support. `anext` became a builtin in 3.10, which is the floor now, so
`F821` no longer fires:
```diff
- anext(aiter_), # type: ignore[arg-type] # noqa: F821
+ anext(aiter_), # type: ignore[arg-type]
```
**Suppressions naming rules the package does not enable** (27), across
`langgraph`, `prebuilt` and `checkpoint-sqlite`: `FBT001`, `FBT002`,
`TC002`, `BLE001`, `ANN001`, `ANN002`, `ANN003`, `E501`, `F401`. Mostly
copied between packages whose rule sets differ.
### One measurement note
If you check these numbers yourself, use `--extend-select`:
```
ruff check --select RUF100 . # 81, misleading
ruff check --extend-select RUF100 . # 33, real
```
With a bare `--select`, ruff treats every other rule as disabled, so
every suppression for another rule looks unused. I quoted 81 before
catching that.
### Verified
`checkpoint-sqlite` 118 passed, `prebuilt` 284 passed, `langgraph` 1968
passed, `checkpoint-postgres` 264 passed on PG 15 and 16. `make lint`
clean in every package.
Independent of #8540 and #8537, so it can land in any order.
## Summary
When `ToolNode` receives a bare `[tool_call]` list via the Send API (the
dispatch shape `create_agent` will use once langchain-ai/langchain#36960
lands), hydrate `ToolRuntime.state` from the current channel values
instead of requiring the dispatcher to inline the full agent state dict
into every `Send.arg`.
Motivation: the paired langchain PR drops the `ToolCallWithContext`
wrapper from `create_agent`'s tool dispatch, which eliminates an O(N²)
storage term on `__pregel_tasks` checkpoint writes. Without this
companion change there would be no path for the tool node to see the
graph state.
## What changed
- `libs/prebuilt/langgraph/prebuilt/tool_node.py` — `_extract_state`
grows a third branch for list-form input. When the input is a list whose
last entry is a `ToolCall` dict, read the current channel values via
`CONFIG_KEY_READ` and return them as the state dict.
The full new logic is four lines inline in `_extract_state`:
```python
read = config.get(CONF, {}).get(CONFIG_KEY_READ)
if read is None:
return {}
# Pregel installs CONFIG_KEY_READ as
# `functools.partial(local_read, scratchpad, channels, managed, task)`.
channels = read.args[1]
return cast("dict[str, Any]", read(list(channels), False))
```
- No changes to the pregel read machinery (`local_read`, `ChannelRead`).
- Only channel values are read; managed values have their own injection
path (`ToolRuntime.context`, `InjectedContext`) and were never in the
pre-fix inlined state dict, so we don't add them here.
- Falls back to `{}` when invoked outside a Pregel context (e.g. direct
`ToolNode(...).invoke([tool_call])` from a test harness), which
preserves existing `ToolNode` direct-invocation test behavior.
- `libs/prebuilt/tests/test_on_tool_call.py` — two new tests covering
the list-form hydration path (sync + async). They build a
`functools.partial` that matches Pregel's real `CONFIG_KEY_READ` shape
and assert `ToolRuntime.state` reflects the current channel values.
## Why it's safe
- **Same snapshot semantics as before.** `Send` is emitted at
end-of-super-step-N; consumed at start-of-super-step-N+1. Channels at
that point reflect every write from super-step N (including the new
AIMessage the tool calls originated from). Parallel tool tasks in the
tools super-step all read the same values since sibling writes don't
land until end-of-super-step.
- **Legacy `ToolCallWithContext` path preserved.** External dispatchers
that still inline state continue to work unchanged — `_extract_state`
checks that branch first.
## Test plan
- [x] `make test` in `libs/prebuilt` — **204 pass**
- [x] Two new hydration tests (sync + async) green
- [x] `make format` / `make lint` / `mypy` clean
---------
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
namespace decisions
```
langgraph.prebuilt
├── ToolRuntime # new
# all of the other stuff that was already there
langgraph.prebuilt.tool_node
├── ToolNode
├── ToolCallRequest # new
├── ToolRuntime # new
├── InjectedState
├── InjectedStore
├── ToolCallWrapper
├── AsyncToolCallWrapper
├── tools_condition
```
```
langchain.tools
├── ToolRuntime # now from langgraph.prebuilt
├── InjectedState # now from langgraph.prebuilt
├── InjectedStore # now from langgraph.prebuilt
├── ToolException
├── tool
├── BaseTool
├── InjectedToolArg
├── InjectedToolCallId
```
