diff --git a/CHANGELOG.md b/CHANGELOG.md
index fffbe545..dfcead28 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **Text** — New `prompt_cache_key` parameter (`TextParameter.PROMPT_CACHE_KEY`) is sent as the provider's `prompt_cache_key` field instead of being warned about and dropped, so requests that share a prompt prefix reach the same cache; mapped on the Open Responses protocol, which defines the field (OpenAI, xAI, Meta, OpenRouter, Ollama), and for Mistral and Moonshot on Chat Completions (#576).
 - **Audio** — Gemini 3.8 TTS (`gemini-3.8-flash-tts`, `gemini-3.8-flash-lite-tts`) accepts Extended Voice Library voices (e.g. `en-us-advisor-1`) and custom `voice_...` / `voicekey_...` ids instead of rejecting them locally; `VoiceConstraint(custom_voices=True)` passes a voice outside the listed catalog through for the provider to validate (#572, #578).
 - **Audio** — ElevenLabs text-to-speech accepts the `ulaw_8000` and `alaw_8000` output formats instead of rejecting them locally; unary and streamed speech in those formats is labeled `AudioMimeType.PCMU` / `AudioMimeType.PCMA` (#587).
+- **Images** — BytePlus Seedream sends `output_format` (`png`, `jpeg`; Seedream 5.0 lite, pro, flash) and `background` (`transparent`, `opaque`; Seedream 5.0 pro, flash) instead of warning about and dropping them (#590).
 
 ### Breaking Changes
 
@@ -23,7 +24,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **Images** — OpenAI `gpt-image-2`, `gpt-image-2.5-flare` and `gpt-image-2.5-sunburst` accept any documented `WIDTHxHEIGHT` size (multiples of 16, 1:3 to 3:1, at most 3840 per edge, 655,360–8,294,400 pixels) with the standard sizes kept as presets, instead of eight fixed sizes (#564).
 - **Text** — Anthropic on Claude on Google Cloud (GoogleADC) sends image and document inputs as base64 sources; the route accepts no URL sources (#570).
 - **Videos** — Google `veo-3.1-generate-preview` is no longer registered: the Gemini API shut it down on October 22, 2026 and now answers 404 `NOT_FOUND`. No Veo model remains registered; Google's replacement is `gemini-omni-1.2-flash` (#585).
-- **Live** — Google `gemini-3.8-live` and `gemini-3.8-live-extended-thinking` constrain `max_tokens` to 1–65,536, the documented output-token limit, as the Google text models do; a larger value raises `ConstraintViolationError` instead of being sent (#590).
+- **Live** — Google `gemini-3.8-live` and `gemini-3.8-live-extended-thinking` constrain `max_tokens` to 1–65,536, the documented output-token limit, as the Google text models do; a larger value raises `ConstraintViolationError` instead of being sent (#591).
 
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