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ChatOpenRouter: Max_retries=0 Enables The SDK Default Retry Policy Instead Of Disabling Retries

Setting max_retries=0 in ChatOpenRouter does not disable retries; the omission of retry_config causes OpenRouter SDK to apply its default backoff policy, leading to unexpected repeated requests and potentially long hangs on 5xx responses.

highConfidence 92%LangChain Affected V<=0.2.8

Origin Analysis

In ChatOpenRouter._build_client, the retry_config parameter is conditionally set only for positive max_retries, otherwise it is left as UNSET. The OpenRouter SDK interprets UNSET as its default retry configuration, not as 'no retries'. Therefore max_retries=0 is silently ignored.

1. Install langchain-openrouter==0.2.8 and openrouter==0.10.0. 2. Instantiate ChatOpenRouter(model='openai/gpt-4o-mini', api_key='unused', max_retries=0). 3. Print model.client.sdk_configuration.retry_config; it shows Unset() instead of None. 4. Send a request to an endpoint that always returns HTTP 500; observe that the client performs multiple retry attempts and continues running, whereas explicit retry_config=None would fail immediately after one request.

Fixing Code Block

0x7F 45 4C 46 02 01 01 000x90 12 AB 04 C1 7E 33 08
0xA4 1C 90 3E 77 0B D2 580x11 F6 6A 2C 80 19 DE 44
0x00 00 00 00 03 00 3E 000x01 00 B7 4D 55 90 0C 61
0x6C 69 62 63 2E 73 6F 2E0x36 00 8E 17 42 AA 05 F3
0xDE C0 DE 01 8B 45 FC 890xC7 5D 20 6F 91 03 E4 78
0x13 37 00 4F 9A 2D E1 700x08 B4 5C 22 71 D0 4A 16
0x48 8D 3D 22 01 00 00 E80x91 FF 0A 63 2E 57 B8 04
0x5A 91 C3 0E 44 70 1B 880x02 6F 39 C4 15 80 ED 27
0xFF 15 40 20 60 00 48 890xC3 90 7A 01 4C 28 B1 56
0x0F 1F 44 00 00 55 48 890xE5 C3 18 6D 92 0B 33 A7

Edge Case Audit

This change requires openrouter SDK version that supports retry_config=None to disable retries (verified in 0.10.0). Users who previously (unintentionally) relied on retries when max_retries=0 may now see immediate failures for transient 5xx errors; this is the documented correct behavior. To roll back, restore the original conditional that omitted retry_config for zero. Ensure that max_retries=None (unset) is not accidentally converted to None, as that would also disable the SDK default retry policy.