Rationale for VS Code

Run Rationale: Search via Commit... from the Command Palette and enter a GitHub commit URL. On first VS Code startup, Rationale offers setup and creates a private Python environment in global storage. First-time Rationale: Configure guides you through choosing a mode and provider, connecting and loading models, then optionally adding GitHub access. Later visits show the full editable configuration page.

API mode calls OpenAI or Anthropic directly and uses provider API billing. The setup checks an API key by requesting the models available to that account, then shows the live model list. Keys are kept in VS Code SecretStorage only after setup is finished. CLI mode invokes an installed and signed-in Codex or Claude Code CLI and uses its account's plan allowance. Codex refreshes from its local model catalog. Claude Code offers its documented current model IDs and account aliases; account availability can vary. CLI credentials are handled by the CLI itself. A custom model ID remains available if it is not listed. GitHub access is optional for public repositories and needed for private repositories. A classic GitHub token needs the repo scope; a fine-grained token needs read access to Contents, Issues, and Pull requests for the repository.

Setup errors appear in a notification and in the Rationale output channel. Analysis runs the bundled artifact retrieval, rationale identification, and summary generation scripts as one-shot Python processes; no backend web server or port is needed. Rationale displays GOAL, NEED, and ALTERNATIVE sections and writes a shareable Markdown file to .rationale/commit-<short-sha>.md at the root of the open Git repository. Rationale identification defaults to one run; change rationale.runs to use repeated runs and majority voting. Python 3.10 through 3.14 are supported. Set rationale.pythonPath if python3 (or python on Windows) is not the Python executable you want to use. Raw analysis artifacts are stored under the extension's global storage directory in runtime/results/.

Run from source

cd vscode-extension
npm ci
npm run debug

This builds the extension and opens a new VS Code Extension Development Host with Rationale loaded. Use Rationale: Configure to enter credentials or Rationale: Search via Commit... to analyze a commit. The first activation installs Python dependencies. The existing Run Rationale Extension launch configuration is also available when you open this folder in VS Code and press F5.

Build a VSIX

npm ci
npm run package

This creates one universal VSIX. The extension bundles the same Python source on every platform and installs dependencies into a private environment using the user's Python installation, so separate VSIX files per OS, architecture, or Python version are not needed. GitHub Actions checks dependency installation on Linux with Python 3.10–3.14, and on macOS and Windows with Python 3.12.