fix(core): propagate RunnableConfig to tools in AgentExecutor (sync/async); support Optional/Union signatures

[raviraj-441]

Issue

Fixes #32671

Summary

• Ensure AgentExecutor propagates RunnableConfig to tools in both sync (invoke/_call) and async (ainvoke/_acall) paths.
• Support tools that accept Optional[RunnableConfig] or Union[RunnableConfig, None] in their signatures.
• Maintain return_direct behavior, async handling with asyncio_timeout, and trimming of intermediate steps.

Implementation notes

• AgentExecutor sets/restores a private current config around invoke/ainvoke using a module-level sentinel and restores it safely (mypy clean).
• Tools receive the config via getattr(self, "_current_config", None) and are invoked with it when present.
• yaml import marked untyped to satisfy mypy; can switch to types-PyYAML if preferred.

Tests

• Added tests cover Optional[RunnableConfig] and Union[RunnableConfig, None] in sync and async tool paths.
• Verified return_direct, async timeout behavior, and intermediate step trimming.
• Core JSON schema recursion tests also pass locally.

Checklist

• No public API changes.
• Full type hints and docs preserved.
• Unit tests added and passing.
• Lint/format and mypy clean for changed files.

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1 Skipped Deployment

Project	Deployment	Preview	Comments	Updated (UTC)
langchain	Ignored	Preview		Sep 8, 2025 5:33pm

[codspeed-hq]

CodSpeed WallTime Performance Report

Merging #32768 will not alter performance

_{Comparing raviraj-441:fix/agents-config-propagation (1405fca) with master (01fdeed)}

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

✅ 13 untouched benchmarks

[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #32768 will not alter performance

_{Comparing raviraj-441:fix/agents-config-propagation (1405fca) with master (01fdeed)}

Summary

✅ 14 untouched benchmarks