标签：#step37flash

Step 3.7 Flash shipped on May 29, 2026 as a structural upgrade to 3.5 Flash: same OpenAI-compatible SDK, new vision encoder, new runtime escalation, and a compute-control flag you can set per request. The migration from 3.5 is two environment variables. One of them has to be exactly right — or every call returns a silent 401. What 3.7 brings that 3.5 didn't Step 3.7 Flash adds three net-new capabilities over 3.5 Flash: a native 1.8B-parameter ViT encoder that injects image representations directly into the language backbone without a separate model call , an automatic Advisor Mode that routes failure-prone subtasks to a larger model at runtime, and a reasoning_effort parameter (low / medium / high) as a first-class API flag rather than a prompt-engineering convention. The production-relevance number is variance: 3.5 Flash scores ranged from 43% to 73% across different harnesses ; 3.7 narrows that to 64.5–71.5% , which matters more for production scheduling than the raw score improvement. Quick Answer: Step 3.7 Flash is an OpenAI-SDK-compatible model — model string step-3.7-flash , base URL https://api.stepfun.ai/v1 (global) or https://api.stepfun.com/v1 (China region). New over 3.5: native vision input, automatic Advisor Mode escalation, and a reasoning_effort flag. The only breaking change from 3.5: base URL must match your account region exactly, or you get a 401 with no error body. The architecture is a 198B sparse MoE model with roughly 11B parameters active per forward pass — dense-10B compute cost at much larger capacity. SWE-Bench Pro improved to 56.3% from 51.3% ; Terminal-Bench 2.1 improved to 59.5% from 53.4% , suggesting the planning and shell-operation gains that matter for coding agents are consistent across benchmarks. Advisor Mode carries the headline cost claim from StepFun's internal harness: 97% of Claude Opus 4.6's coding performance at $0.19 vs. $1.76 per task . That's a vendor figure on a first-party SWE-Bench Verified run — treat it as directio