Doubao Seed Evolving
ByteDance Seed · China · 2026
A model sold without a version number: one model ID, quietly replaced every few weeks, with a million-token context for coding agents.
Doubao Seed Evolving is ByteDance's answer to version fatigue: instead of shipping Seed 2.2, then 2.3, the company ships one permanent model ID — doubao-seed-evolving — and replaces what sits behind it on a rolling schedule. The documentation states the principle plainly: upgrades take effect automatically, with no endpoint migration and no change to the call. The page also carries a line the industry rarely publishes, a dated note reading 'version updated 2026/08/01'. Technically it is the widest-context model ByteDance offers. The context window is 1,024,000 tokens against 256,000 for the Seed 2.1 family, with up to 256,000 tokens of output and 256,000 of chain of thought. It is explicitly a branch model for coding and agent work: text, images, video and documents in, function calling, structured output and context caching, with audio deliberately left out. Deep thinking is on by default and adjustable through a reasoning_effort setting with four levels. The API speaks both the OpenAI and the Anthropic protocol, so the model drops into Claude Code, OpenCode and Codex without a wrapper. On Volcano Engine it is listed at 6 yuan per million input tokens and 30 per million output — the same as Seed 2.1 Pro, for four times the context. ByteDance describes the August build as better at repository-scale fixes, cross-file edits and long unattended runs, and singles out hallucination in search results and tool calls as the area most improved. The delivery model has a cost that ByteDance does not discuss. A model with no frozen version is a model with no reproducible reference point: a benchmark score, an audit or a published evaluation describes whatever was behind the ID that week, and cannot be re-run against the same weights later. For catalogues, regulators and anyone who has to certify a system, that is a real change — and it is the reason this profile records the model as a rolling release rather than a dated one.
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