Docs: Added initial draft for v0.26.0 release notes. (#15603)

### What problem does this PR solve?

Initial draft for v0.26.0 release notes.

### Type of change


- [x] Documentation Update

docs/release_notes.md

@@ -9,6 +9,56 @@ sidebar_custom_props: {
 
 Key features, improvements and bug fixes in the latest releases.
 
+## v0.26.0
+
+Released on June 11, 2026.
+
+### New features
+
+- **Model providers**
+  - Implements auto-populated model lists for multiple providers, eliminating the need to type model names manually. This feature currently supports: Ollama, OpenRouter, vLLM, OpenAI-API-Compatible, LM-Studio, VolcEngine, Xinference, LocalAI, BaiduYiyan, GPUStack, and Fish Audio.
+  - Allows configuring multiple API keys for the same model provider. [#14595](https://github.com/infiniflow/ragflow/pull/14595)
+  - Dynamically populates model selection dropdowns in the UI by fetching the currently available models directly from remote model providers. [#15711](https://github.com/infiniflow/ragflow/pull/15711)
+- **Data source connectors**: Implements new data source connectors for Outlook, OneDrive, Microsoft Teams, Slack, SharePoint, Salesforce, and Azure Blob Storage. [#15333](https://github.com/infiniflow/ragflow/pull/15333)[#15330](https://github.com/infiniflow/ragflow/pull/15330)[#15332](https://github.com/infiniflow/ragflow/pull/15332)[#15188](https://github.com/infiniflow/ragflow/pull/15188)[#15190](https://github.com/infiniflow/ragflow/pull/15190)[#15462](https://github.com/infiniflow/ragflow/pull/15462)[#15466](https://github.com/infiniflow/ragflow/pull/15466)
+- **Dataset** - Implements a checkpoint and resume feature for community extraction and entity resolution, the most expensive and time-consuming parts of the GraphRAG indexing pipeline. [#15518](https://github.com/infiniflow/ragflow/issues/15518)[#15523](https://github.com/infiniflow/ragflow/pull/15523)
+
+### Improvements
+
+- Removes `<think>` text buffering to ensure reasoning-capable models feel faster and more transparent during interactions. [#15891](https://github.com/infiniflow/ragflow/pull/15891)
+- Marks MySQL migrations as applied. [#15504](https://github.com/infiniflow/ragflow/pull/15504)
+
+### Model Support
+
+- Four new SiliconFlow models [#15383](https://github.com/infiniflow/ragflow/pull/15383)
+- MiniMax-M3 model [#15513](https://github.com/infiniflow/ragflow/pull/15513)
+- Latest Anthropic models [#15516](https://github.com/infiniflow/ragflow/pull/15516)
+- Voyage 4 model family [#15516](https://github.com/infiniflow/ragflow/pull/15516)
+- Cohere model list. [#15576](https://github.com/infiniflow/ragflow/pull/15576)
+
+### i18n
+
+- Completes Korean translation. [#15863](https://github.com/infiniflow/ragflow/pull/15863)
+- Completes Italian translation. [#15729](https://github.com/infiniflow/ragflow/pull/15729)
+
+### Bug fixes
+
+- The thinking mode of MiniMax models was not correctly enabled. [#15496](https://github.com/infiniflow/ragflow/pull/15496)
+- Infinite loops were triggered when the thinking mode was enabled for Qwen3.5 and Qwen3.6 models. [#15101](https://github.com/infiniflow/ragflow/pull/15101)
+- Streamed answers were being duplicated when using the OpenAI-compatible chat completions API endpoint. [#15286](https://github.com/infiniflow/ragflow/issues/15286)[#15443](https://github.com/infiniflow/ragflow/pull/15443)
+- Serialization errors were caused during chat completions when invalid numeric scores like `NaN` (Not-a-Number) or `Inf` (Infinity) were passed to the JSON encoder. [#15245](https://github.com/infiniflow/ragflow/issues/15245)[#15266](https://github.com/infiniflow/ragflow/pull/15266)
+- Chat completions using LiteLLM providers were failing because unrecognized internal configuration parameters were not being filtered out before reaching the external APIs. [#15427](https://github.com/infiniflow/ragflow/issues/15427)[#15432](https://github.com/infiniflow/ragflow/pull/15432)
+- The OpenAI-compatible chat completions API was defaulting to streamed responses. [#15356](https://github.com/infiniflow/ragflow/issues/15356)[#15394](https://github.com/infiniflow/ragflow/pull/15394)
+- Empty `AND` results were incorrectly dropped during metadata filtering. [#15477](https://github.com/infiniflow/ragflow/pull/15477)
+- Repetitive page chrome, such as headers and footers, was incorrectly extracted as main text by the MinerU parser. [#15335](https://github.com/infiniflow/ragflow/issues/15335)[#15387](https://github.com/infiniflow/ragflow/pull/15387)
+- English chart titles were missing during document extraction in the DeepDoc module. [#15481](https://github.com/infiniflow/ragflow/pull/15481)
+- Empty outputs were returned by the TitleChunker for `json` and `chunks` upstream formats [#14247](https://github.com/infiniflow/ragflow/pull/14247)[#15396](https://github.com/infiniflow/ragflow/pull/15396)
+- An error message was missing when a .tsv file upload attempt failed. [#15284](https://github.com/infiniflow/ragflow/pull/15284)
+- API tokens missing beta values caused token retrieval errors. [#15405](https://github.com/infiniflow/ragflow/pull/15405)
+- Caps the maximum page size to fix system crashes or slowdowns from large queries. [#15292](https://github.com/infiniflow/ragflow/pull/15292)
+- Client errors were caused by the OpenAI-compatible chat completion API incorrectly defaulting to streamed responses. [#15356](https://github.com/infiniflow/ragflow/issues/15356)[#15394](https://github.com/infiniflow/ragflow/pull/15394)
+- HTTP 500 internal server errors were triggered instead of standard 4xx client errors when users attempted to download missing files from the storage backend. [#15369](https://github.com/infiniflow/ragflow/issues/15369)[#15371](https://github.com/infiniflow/ragflow/pull/15371)
+- GraphRAG entity ranking was broken. [#15795](https://github.com/infiniflow/ragflow/issues/15795)[#15797](https://github.com/infiniflow/ragflow/pull/15797)
+
 ## v0.25.6
 
 Released on May 26, 2026.