docs: fix docstring inaccuracies and update outdated LangSmith URLs (#35283)

Fix several docstring inaccuracies in langchain-core and update outdated
LangSmith URLs across three README files.

**Docstring fixes (libs/core):**
- `tap_output_iter`: docstring says "async iterator" but method accepts
sync `Iterator`
- `agenerate_from_stream`: docstring says "Iterator" but method accepts
`AsyncIterator`
- `BaseLLM.OutputType`: docstring says "input type" but property returns
output type
- Grammar: "or deprecated" → "or be deprecated", "relies" → "rely",
"whose the" → "whose"

**URL fixes (libs/core, libs/langchain, libs/langchain_v1):**
- Updated `smith.langchain.com` → `www.langchain.com/langsmith` (root
README already uses the correct URL)

Verified with `make lint` and `make format` in libs/core — no new issues
introduced. Changes are docs-only with no code logic impact.

*This PR was created with assistance from an AI coding tool.*

libs/core/README.md

@@ -7,8 +7,8 @@
 
 Looking for the JS/TS version? Check out [LangChain.js](https://github.com/langchain-ai/langchainjs).
 
-To help you ship LangChain apps to production faster, check out [LangSmith](https://smith.langchain.com).
-[LangSmith](https://smith.langchain.com) is a unified developer platform for building, testing, and monitoring LLM applications.
+To help you ship LangChain apps to production faster, check out [LangSmith](https://www.langchain.com/langsmith).
+[LangSmith](https://www.langchain.com/langsmith) is a unified developer platform for building, testing, and monitoring LLM applications.
 
 ## Quick Install
 

libs/core/langchain_core/language_models/chat_models.py

@@ -214,7 +214,7 @@ async def agenerate_from_stream(
     """Async generate from a stream.
 
     Args:
-        stream: Iterator of `ChatGenerationChunk`.
+        stream: AsyncIterator of `ChatGenerationChunk`.
 
     Returns:
         Chat result.
@@ -310,7 +310,7 @@ class BaseChatModel(BaseLanguageModel[AIMessage], ABC):
     - If `False` (Default), will always use streaming case if available.
 
     The main reason for this flag is that code might be written using `stream` and
-    a user may want to swap out a given model for another model whose the implementation
+    a user may want to swap out a given model for another model whose implementation
     does not properly support streaming.
     """
 

libs/core/langchain_core/language_models/llms.py

@@ -311,7 +311,7 @@ class BaseLLM(BaseLanguageModel[str], ABC):
     @property
     @override
     def OutputType(self) -> type[str]:
-        """Get the input type for this `Runnable`."""
+        """Get the output type for this `Runnable`."""
         return str
 
     def _convert_input(self, model_input: LanguageModelInput) -> PromptValue:

libs/core/langchain_core/tracers/log_stream.py

@@ -264,8 +264,9 @@ class LogStreamCallbackHandler(BaseTracer, _StreamingCallbackHandler):
                 - `'original'` is the format used by all current tracers. This format is
                     slightly inconsistent with respect to inputs and outputs.
                 - 'streaming_events' is used for supporting streaming events, for
-                    internal usage. It will likely change in the future, or deprecated
-                    entirely in favor of a dedicated async tracer for streaming events.
+                    internal usage. It will likely change in the future,
+                    or be deprecated entirely in favor of a dedicated async
+                    tracer for streaming events.
 
         Raises:
             ValueError: If an invalid schema format is provided (internal use only).
@@ -356,7 +357,7 @@ class LogStreamCallbackHandler(BaseTracer, _StreamingCallbackHandler):
             yield chunk
 
     def tap_output_iter(self, run_id: UUID, output: Iterator[T]) -> Iterator[T]:
-        """Tap an output async iterator to stream its values to the log.
+        """Tap an output iterator to stream its values to the log.
 
         Args:
             run_id: The ID of the run.
@@ -673,7 +674,7 @@ async def _astream_log_implementation(
     """Implementation of astream_log for a given runnable.
 
     The implementation has been factored out (at least temporarily) as both
-    `astream_log` and `astream_events` relies on it.
+    `astream_log` and `astream_events` rely on it.
 
     Args:
         runnable: The runnable to run in streaming mode.

libs/langchain/README.md

@@ -7,8 +7,8 @@
 
 Looking for the JS/TS version? Check out [LangChain.js](https://github.com/langchain-ai/langchainjs).
 
-To help you ship LangChain apps to production faster, check out [LangSmith](https://smith.langchain.com).
-[LangSmith](https://smith.langchain.com) is a unified developer platform for building, testing, and monitoring LLM applications.
+To help you ship LangChain apps to production faster, check out [LangSmith](https://www.langchain.com/langsmith).
+[LangSmith](https://www.langchain.com/langsmith) is a unified developer platform for building, testing, and monitoring LLM applications.
 
 ## Quick Install
 

libs/langchain_v1/README.md

@@ -7,8 +7,8 @@
 
 Looking for the JS/TS version? Check out [LangChain.js](https://github.com/langchain-ai/langchainjs).
 
-To help you ship LangChain apps to production faster, check out [LangSmith](https://smith.langchain.com).
-[LangSmith](https://smith.langchain.com) is a unified developer platform for building, testing, and monitoring LLM applications.
+To help you ship LangChain apps to production faster, check out [LangSmith](https://www.langchain.com/langsmith).
+[LangSmith](https://www.langchain.com/langsmith) is a unified developer platform for building, testing, and monitoring LLM applications.
 
 ## Quick Install