Docs: Initial draft for v0.25.6 release notes. (#15250)

### What problem does this PR solve?

Initial draft: v0.25.6 release notes.

### Type of change

- [x] Documentation Update

docs/release_notes.md

@@ -9,6 +9,38 @@ sidebar_custom_props: {
 
 Key features, improvements and bug fixes in the latest releases.
 
+## v0.25.6
+
+Released on May 26, 2026.
+
+### New features
+
+- Agent: Adds a **Browser** component for AI-driven browser automation. [#14888](https://github.com/infiniflow/ragflow/pull/14888)
+
+### Improvements
+
+- RAG: RAPTOR construction now introduces AHC mode (Ψ-RAG), which expands semantics from the document level to the dataset level. Not only is index construction performance significantly higher than the previous RAPTOR, but it also outperforms the old RAPTOR on Recall@5 and average F1. Users can switch between AHC and GMM modes. This feature was introduced in v0.25.3, and this release fixes several bugs. [#14674](https://github.com/infiniflow/ragflow/issues/14674)[#14679](https://github.com/infiniflow/ragflow/pull/14679)
+- Agent: @tool decorator for Chat Model tool registration.
+- Agent: Agent messages now support displaying base64 images.
+- Agent: Doc Generator exposes file metadata as discrete outputs. [#15080](https://github.com/infiniflow/ragflow/pull/15080)
+- Agent: Agent chat completion supports passing chat_template_kwargs.
+
+### Bug fixes
+
+- Fixes `/chat/completions` to allow sending only latest message in API payload and removes requirement to transmit full conversation history. [#15197](https://github.com/infiniflow/ragflow/pull/15197) See also [Converse with chat assistant](./references/http_api_reference.md#converse-with-chat-assistant).
+- Weight assigned to vector similarity was not applied during the retrieval phase. [#15108](https://github.com/infiniflow/ragflow/pull/15108)
+- Fixes parser configs not saving on dataset configuration page.
+- Logs wer not fully displayed on data source details page.
+- Fixes document status filtering failure.
+- Fixes crash guard for empty LLM choices responses.
+- RAG: RAPTOR construction process halted when using the [Infinity](https://github.com/infiniflow/infinity) document engine. [#14998](https://github.com/infiniflow/ragflow/pull/14998)
+- Fixes streaming response parsing for Mistral/Upstage reasoning models.
+- Fixes HTML tags in ingestion pipeline parser output.
+- Fixes table parser metadata.
+- Fixes asyncio event loop nesting and fire-and-forget task issues.
+- Fixes asyncio.Semaphore bound to different event loop error.
+- Agent: Fixes **Agent** component prompt variable disappearing and search vector_similarity_weight issues.
+
 ## v0.25.5
 
 Released on May 20, 2026.
@@ -36,8 +68,8 @@ Released on May 20, 2026.
 - Agent: Fixed MCP tool name duplication.[#14217](https://github.com/infiniflow/ragflow/pull/14217)
 - Agent: top_k passing issues [#14760](https://github.com/infiniflow/ragflow/pull/14760)
 - Chat file attachment loss. [#13993](https://github.com/infiniflow/ragflow/pull/13993)
-- IMAP multi-address parsing [#15006](https://github.com/infiniflow/ragflow/pull/15006)
-- Langfuse token usage reporting. [#13294](https://github.com/infiniflow/ragflow/pull/13294)
+- IMAP synchronization process crashed when multiple email addresses or quoted commas were detected in "From" header. [#14963](https://github.com/infiniflow/ragflow/issues/14963)[#14964](https://github.com/infiniflow/ragflow/issues/14964)[#15006](https://github.com/infiniflow/ragflow/pull/15006)
+- Langfuse integration failed to track token consumption. [#9837](https://github.com/infiniflow/ragflow/issues/9837)[#13294](https://github.com/infiniflow/ragflow/pull/13294)
 - Enhances the stability and fault tolerance of the reranking module by implementing network timeouts, crash-prevention safeguards, and specific provider bug fixes. [#14264](https://github.com/infiniflow/ragflow/pull/14264)
 - Increases minimum supported Nginx to 1.31.0. [#14928](https://github.com/infiniflow/ragflow/issues/14928)[#15007](https://github.com/infiniflow/ragflow/pull/15007)
 
@@ -68,7 +100,6 @@ Released on May 13, 2026.
 
 ### New features
 
-- Data source and parsing: Added column-level semantic/metadata control for the spreadsheet file parser; introduced ETag optimization for incremental synchronization of S3 data sources to avoid unnecessary file transfers.
 - Enables assigning specific roles like content, metadata, and primary key, to table columns. [#13710](https://github.com/infiniflow/ragflow/pull/13710)
 
 ### Improvements