# CLAUDE.md

Guidance for Claude Code (claude.ai/code) in this repo.

## Project

Novel Software: software for planning and writing a novel. ASP.NET Core 10, C#, TypeScript, React. Chapter outlines, character dossiers, prose drafting, an embedded Claude agent, and an MCP server over the same API.

## Structure

- `src/NovelSoftware.Domain/` — entities and enums, no dependencies
- `src/NovelSoftware.Application/` — services, DTOs, the agent tool-use loop
- `src/NovelSoftware.Infrastructure/` — EF Core + SQLite, Anthropic SDK client
- `src/NovelSoftware.Api/` — minimal API endpoints
- `src/NovelSoftware.Mcp/` — MCP stdio server
- `src/NovelSoftware.Web/` — React + Vite client
- `tests/` — test suite
- `docs/` — documentation

## Best Practices

- Use latest .NET + latest supported nuget packages for that version
- Set `langVersion` to latest in all csproj files; enable nullable
- Organize code by feature/area, not type
- New features need unit tests covering logic as much as possible
- Modified file: check missing test coverage, all tests pass

## Architecture

- The React client, the embedded agent, and the MCP server all go through the same REST API. One source of truth — never let a client reach past the API to the database.
- Agent tools and MCP tools call the same application services the endpoints do. New capability = new service method, then surface it in all three.
- Domain has no dependencies. Application depends on Domain. Infrastructure depends on Application. Nothing depends on Api.

# Coding

- Descriptive names all classes/methods. No generic: Provider, Manager, Helper
- Match formatting/style from `.editorconfig`
- Wrap lines at 220 chars, single line if fewer
- Interfaces implemented by single class → bottom of class file. Interface w/ multiple implementations → separate file.
- No tuples for return types. Prefer records or classes for multiple values
- Use `record` for data objects, `class` for objects with behavior. Avoid mutable state where possible.
- DTOs are records; entities are classes
- `PATCH` requests are partial: null field = leave alone, empty string = clear. Keep new update endpoints consistent with `Patch.Apply`.
- Enums cross the wire as names, never ordinals

## Testing

- Min 70% code coverage, target 90%. Unit tests focus end-user scenarios first.
- Don't write tests just for coverage. Call out missing coverage rather than cover stuff not valuable to end user.
- Code not cleanly unit-testable → mark `[ExcludeFromCodeCoverage]` or exclude namespace from coverage in .runsettings file
- BDD-style unit tests, end-to-end as possible. e.g. `Deleting_a_scene_leaves_its_beats_alone`
- xUnit + FluentAssertions
- Tests run against real in-memory SQLite via `TestDatabase`, not the EF InMemory provider — cascade deletes and query translation must be exercised, and the InMemory provider fakes both
- Model calls are faked at the `IAgentModelClient` seam (see `ScriptedModelClient`). Never hit the Anthropic API from a test.
- No "Mock" in mocked object names
- No Arrange/Act/Assert comments
- All tests pass before commit

## Verifying

Build and tests passing is not the same as working. For anything touching an endpoint, the agent loop, or the MCP server, run it:

- API: `ASPNETCORE_URLS=http://localhost:5080 dotnet run --project src/NovelSoftware.Api`, then exercise the route with curl
- Web: `cd src/NovelSoftware.Web && npm run dev` — proxies `/api` to :5080
- MCP: build it, then drive it over stdio JSON-RPC (`initialize` → `notifications/initialized` → `tools/list` → `tools/call`)

Several real bugs here — SQLite refusing to ORDER BY a DateTimeOffset, the agent's model client throwing at construction and taking read-only endpoints down with it — passed the build and the test suite and only showed up when the app actually ran.

## Claude

- Plans = `.md` files in `docs/plans/`. Web → `docs/plans/web/`, API → `docs/plans/api/`
- Split large plans into discrete chunks — each buildable + committable independently
- Plan generated from `docs/plans/<name>.md` → save as `docs/plans/<name>_plan.md`
- Plan implemented from `docs/plans/<name>.md` → save summary as `docs/plans/<name>_output.md`

## Stack

`.gitignore` set for .NET/Visual Studio (C#, NuGet, MSBuild) plus Node. Update if stack change.

- Anthropic model id lives in `appsettings.json` under `Agent:Model`. Don't hardcode it.
- API key comes from `ANTHROPIC_API_KEY` or `Agent:ApiKey` — never commit one. The app must stay fully usable without a key; only the agent endpoints require it.
- EF migrations: `dotnet ef migrations add <Name> -p src/NovelSoftware.Infrastructure -s src/NovelSoftware.Api -o Persistence/Migrations`. The API migrates on boot.