Add deepseek-v4.1-flash to alibaba-cn provider

[Spin-Particle]

Adds DeepSeek V4.1 Flash to the Alibaba Bailian pay-as-you-go provider (alibaba-cn, Beijing), using the existing lab entry models/deepseek/deepseek-v4.1-flash.toml via base_model.

Sources (accessed 2026-09-18):

• https://bailian.console.aliyun.com/cn-beijing?tab=model#/model-market/detail/deepseek-v4.1-flash?serviceSite=asia-pacific-china — Beijing model card
• https://help.aliyun.com/zh/model-studio/deepseek-api — capability table, reasoning controls, max_tokens default
• https://help.aliyun.com/zh/model-studio/billing-for-model-studio — Beijing peak/off-peak pricing

Host-specific deltas vs the lab entry:

• Hybrid reasoning with both controls. enable_thinking = true|false toggles thinking (the deepseek doc classifies the v4 family as hybrid-thinking models on this host), and reasoning_effort accepts low / high / max with default high — the doc's capability table explicitly lists low as supported for deepseek-v4.1-flash (only v4.1-flash, v4-flash-0731 and v4-pro-0813 support low). reasoning_content streams in deltas.
• Cost: peak/off-peak (峰谷) pricing. Beijing lists CNY 2/1 (peak/off-peak) input and 8/4 output per 1M tokens with context-cache discount. Following the existing convention on this host (deepseek-v4-flash-0731 / deepseek-v4-pro-0813 record the peak price), this entry records the peak price converted to USD: 0.278 / 1.111 / 0.014 (cache read).
• Responses API supported on Beijing and Singapore only; chat completions available everywhere.
• Limits and modalities are identical to the lab entry (1M context, 384_000 output, text+image input), so they are inherited and not restated (override-only). Note the host's own default max_tokens is 393_216 shared with thinking, but the model's max output is 384_000 per the lab entry.

Not added to alibaba (international) — the international gateway's model list prices in a different rate card (Singapore peak CNY 2.188/8.75); it can be added separately once pricing is confirmed. Also not added to token-plan / coding-plan catalogs — the Beijing pay-as-you-go catalog is what the model market page lists.

Related: #7148 added v4.1-flash to alibaba-token-plan (Singapore) earlier; this fills the Beijing pay-as-you-go gap.

bun validate passes.

[github-actions]

Action items

• [medium] [violation] providers/alibaba-cn/models/deepseek-v4.1-flash.toml:17 - Check: CNY costs must be converted to USD/MTok with rate and date in a leading top-of-file comment. Why: The file authors USD 0.278 / 1.111 / 0.014 from Beijing CNY peak prices but never records the FX rate, date, or rate source, so the conversion cannot be audited or reproduced. Action: Add a leading comment with the CNY→USD rate, date, and source (same pattern as qwen3.8-flash.toml / qwen3.7-flash.toml on this host), e.g. # CNY→USD rate: X.XXXX, YYYY-MM-DD, source: ….