Add context_windows config to README.md Configuration template

Author: beacoder

README.md

@@ -122,6 +122,10 @@ All LLM settings live in a single JSON configuration file. Environment variables
       "model": "qwen3.5-coder"
     }
   },
+  "context_windows": {
+    "_comment": "Optional per-model context-window overrides (tokens). Keys are model names or fnmatch patterns (e.g. deepseek-v4* = 1000000); matched in file order, first match wins. Overrides the built-in CONTEXT_WINDOWS table in config.py.",
+    "deepseek-v4*": 1000000
+  },
   "subagent_llm": {
     "profile": null,
     "base_url": null,
@@ -161,6 +165,7 @@ All LLM settings live in a single JSON configuration file. Environment variables
 
 - **`llm`** — main LLM configuration. Optional keys include `backend`, `temperature`, `max_tokens`, `timeout`, `reasoning_effort`, and `stream`. Values such as `reasoning_effort` are passed to the API as-is when set. `run --no-stream` overrides `stream`.
 - **`models`** — named LLM profiles for runtime switching with `/model`. A profile is a partial settings dictionary; unset keys inherit from the main `llm`. `default` restores the main LLM configuration.
+- **`context_windows`** — optional per-model context-window overrides (tokens). Keys are model names or fnmatch patterns (e.g., `deepseek-v4*`); matched in file order, first match wins. Overrides the built-in `CONTEXT_WINDOWS` table in `config.py`.
 - **`subagent_llm`** — LLM configuration for `Agent` tool requests. Unset values inherit from the main `llm`. Set `profile` to reuse a profile from `models`. Precedence is: profile settings > explicit `subagent_llm` settings > main `llm` > environment variables.
 - **`paths.context_path` / `paths.skill_path`** — locations from which to load context files and skills. When unset, the project-local `<project>/contexts` and `<project>/skills` directories are used.
 - **`mcp.servers`** — MCP server configuration. Requires the `[mcp]` extra. Each server supports `transport`, `command`, `args`, `env`, `url`, `headers`, `parallel`, `timeout`, and `enabled`.