fix(langchain): tighten structured output model fallbacks#38042
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Provider-native structured output fallback detection now uses bounded model-name patterns instead of broad substring checks, reducing false positives for unrelated model IDs. The model examples and test fixtures across OpenAI/OpenRouter-facing code were refreshed around current OpenAI model families while preserving shipped defaults. ## Changes - Tightened `FALLBACK_MODELS_WITH_STRUCTURED_OUTPUT` from loose string fragments to regex patterns, with `_supports_provider_strategy` matching full model-name segments instead of arbitrary substrings. - Expanded structured-output fallback coverage for newer OpenAI, Anthropic, and xAI/Grok model families, including `gpt-5.x`, newer Claude 4/5-style names, and `grok-build`. - Reused `_attempt_infer_model_provider` in provider tool search routing so `_provider_from_model_name` follows the same provider inference behavior as `init_chat_model`. - Suppressed irrelevant provider-inference deprecation warnings during provider tool search registry lookup. - Refreshed OpenAI, Azure OpenAI, OpenRouter, core metadata, and example model references from older fixtures like `gpt-4`, `gpt-4o`, `o1`, and `o4-mini` to current test/profile models such as `gpt-5.5`, `gpt-5-nano`, and `gpt-4.1-mini`. - Removed outdated OpenAI test assumptions around legacy `o1` behavior and narrowed legacy structured-output checks to explicitly legacy model names.
Mason Daugherty (mdrxy)
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ccurme (ccurme) and
Eugene Yurtsev (eyurtsev)
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June 11, 2026 01:04
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Provider-native structured output fallback detection now uses bounded model-name patterns instead of broad substring checks, reducing false positives for unrelated model IDs. The model examples and test fixtures across OpenAI/OpenRouter-facing code were refreshed around current OpenAI model families while preserving shipped defaults.
Changes
FALLBACK_MODELS_WITH_STRUCTURED_OUTPUTfrom loose string fragments to regex patterns, with_supports_provider_strategymatching full model-name segments instead of arbitrary substrings.gpt-5.x, newer Claude 4/5-style names, andgrok-build._attempt_infer_model_providerin provider tool search routing so_provider_from_model_namefollows the same provider inference behavior asinit_chat_model.gpt-4,gpt-4o,o1, ando4-minito current test/profile models such asgpt-5.5,gpt-5-nano, andgpt-4.1-mini.o1behavior and narrowed legacy structured-output checks to explicitly legacy model names.