doc: Add development notes for mitmproxy setup

README.md

@@ -56,6 +56,51 @@ For more info on how to configure OpenCode [**head over to our docs**](https://o
 
 ### Contributing
 
+OpenCode is an opinionated tool so any fundamental feature needs to go through a
+design process with the core team.
+
+> [!IMPORTANT]
+> We do not accept PRs for core features.
+
+However we still merge a ton of PRs - you can contribute:
+
+- Bug fixes
+- Improvements to LLM performance
+- Support for new providers
+- Fixes for env specific quirks
+- Missing standard behavior
+- Documentation
+
+Take a look at the git history to see what kind of PRs we end up merging.
+
+> [!NOTE]
+> If you do not follow the above guidelines we might close your PR.
+
+To run OpenCode locally you need.
+
+- Bun
+- Golang 1.24.x
+
+And run.
+
+```bash
+$ bun install
+$ bun dev
+```
+
+#### Development Notes
+
+To look behind the scene and report in an issue what OpenCode is sending:
+
+- Set up `mitmproxy` with `uv tool install mitmproxy`.
+- Start it by running `mitmweb`.
+- Trust the certificate](https://docs.mitmproxy.org/stable/concepts/certificates/)
+- Run opencode like so:
+  ```bash
+  HTTP_PROXY=http://127.0.0.1:8080 HTTPS_PROXY=http://127.0.0.1:8080 NODE_EXTRA_CA_CERTS="$HOME/.mitmproxy/mitmproxy-ca-cert.pem" opencode
+  ```
+
+**API Client**: After making changes to the TypeScript API endpoints in `packages/opencode/src/server/server.ts`, you will need the OpenCode team to generate a new stainless sdk for the clients.
 If you're interested in contributing to OpenCode, please read our [contributing docs](./CONTRIBUTING.md) before submitting a pull request.
 
 ### FAQ