docs: add en readme

Author: razmser

README.md

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+# CoreInfra OpenCode Plugin
+
+Plugin for [OpenCode](https://opencode.ai) that adds [CoreInfra AI Hub](https://hub.coreinfra.ai/) as an external model provider.
+
+## Installation
+
+**Important:** requires OpenCode version 1.4.0 or newer
+
+```bash
+# Install the plugin
+opencode plugin -g 'coreinfra-opencode-plugin@github:CoreInfraAI/opencode-plugin'
+# Log in by entering the API token
+opencode providers login --provider coreinfra
+```
+
+During authentication, you will need a [CoreInfra AI Hub](https://hub.coreinfra.ai/) API token.
+
+## Features
+
+- **Up-to-date model list** - the catalog is loaded dynamically from the Hub API on every startup and always reflects its current state.
+- **OpenAI and Anthropic models** - both model families are supported, including GPT-5.x and Claude 4.x.
+- **Reasoning support** - `interleaved thinking` mode is enabled automatically for Anthropic models.
+
+## Limitations
+
+At the moment, OpenCode supports prices in USD only.
+Because of that, pricing is not overridden yet: OpenCode shows prices from the original OpenAI/Anthropic API.
+
+## Usage
+
+After installation and authentication, models will be available with the `coreinfra/` prefix:
+
+```bash
+opencode run -m coreinfra/gpt-5.4-nano
+opencode run -m coreinfra/claude-sonnet-4-20250514
+```
+
+To see the full list of available models:
+
+```bash
+opencode models coreinfra
+```
+
+## Supported Models
+
+The full model list is determined by the Hub contents at startup time. The plugin supports all models listed on this page:
+https://hub.coreinfra.ai/pricing
+
+## Development
+
+Code formatting:
+
+```bash
+just fmt
+```
+
+Full project check:
+
+```bash
+just check
+```