fix(core): strip injected args before validation for strict schemas

[thromel]

Summary

• Fix StructuredTool with strict args_schema (extra="forbid") rejecting injected arguments

Problem

When using StructuredTool with a Pydantic args_schema that has model_config = {"extra": "forbid"}, injected arguments (annotated with InjectedToolArg) cause a validation error:

pydantic_core._pydantic_core.ValidationError: 1 validation error for ArgsSchema
runtime
  Extra inputs are not permitted

This happens because injected args are passed to model_validate() before being stripped, and Pydantic's strict mode rejects them as unknown fields.

Solution

Extract injected args that are NOT declared in the schema before validation, then re-add them after validation completes. This:

• Allows injected args to work with strict Pydantic schemas
• Maintains backward compatibility for schemas where injected args ARE declared as fields
• Follows the documented behavior that injected args should be "hidden from the model" and "injected during execution"

Test Plan

• Added regression test test_tool_injected_arg_with_strict_schema
• All existing tool tests pass (149 passed, 1 skipped)
• Ruff lint passes

Fixes #34246

[codspeed-hq]

CodSpeed Performance Report

Merging #34248 will not alter performance

_{Comparing thromel:fix/injected-args-strict-schema (d8f2351) with master (dff229d)¹}

⚠️ 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
⏩ 21 skipped²

Footnotes

1. No successful run was found on master (2aa0555) during the generation of this report, so dff229d was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

2. 21 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩