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@@ -18,3 +18,5 @@ node_modules
 yarn-error.log
 ts/.svelte-kit
 .yarn
+.claude/settings.local.json
+CLAUDE.local.md
diff --git a/CLAUDE.md b/CLAUDE.md
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+# Claude Code Configuration
+
+## Project Overview
+
+Anki is a spaced repetition flashcard program with a multi-layered architecture. Main components:
+
+- Web frontend: Svelte/TypeScript in ts/
+- PyQt GUI, which embeds the web components in aqt/
+- Python library which wraps our rust Layer (pylib/, with Rust module in pylib/rsbridge)
+- Core Rust layer in rslib/
+- Protobuf definitions in proto/ that are used by the different layers to
+  talk to each other.
+
+## Building/checking
+
+./check (check.bat) will format the code and run the main build & checks.
+Please do this as a final step before marking a task as completed.
+
+## Quick iteration
+
+During development, you can build/check subsections of our code:
+
+- Rust: 'cargo check'
+- Python: './tools/dmypy'
+- TypeScript/Svelte: './ninja check:svelte'
+
+Be mindful that some changes (such as modifications to .proto files) may
+need a full build with './check' first.
+
+## Build tooling
+
+'./check' and './ninja' invoke our build system, which is implemented in build/. It takes care of downloading required deps and invoking our build
+steps.
+
+## Translations
+
+ftl/ contains our Fluent translation files. We have scripts in rslib/i18n
+to auto-generate an API for Rust, TypeScript and Python so that our code can
+access the translations in a type-safe manner. Changes should be made to
+ftl/core or ftl/qt. Except for features specific to our Qt interface, prefer
+the core module. When adding new strings, confirm the appropriate ftl file
+first, and try to match the existing style.
+
+## Protobuf and IPC
+
+Our build scripts use the .proto files to define our Rust library's
+non-Rust API. pylib/rsbridge exposes that API, and _backend.py exposes
+snake_case methods for each protobuf RPC that call into the API.
+Similar tooling creates a @generated/backend TypeScript module for
+communicating with the Rust backend (which happens over POST requests).
+
+## Fixing errors
+
+When dealing with build errors or failing tests, invoke 'check' or one
+of the quick iteration commands regularly. This helps verify your changes
+are correct. To locate other instances of a problem, run the check again -
+don't attempt to grep the codebase.
+
+## Ignores
+
+The files in out/ are auto-generated. Mostly you should ignore that folder,
+though you may sometimes find it useful to view out/{pylib/anki,qt/_aqt,ts/lib/generated} when dealing with cross-language communication or our other generated sourcecode.
+
+## Launcher/installer
+
+The code for our launcher is in qt/launcher, with separate code for each
+platform.
+
+## Rust dependencies
+
+Prefer adding to the root workspace, and using dep.workspace = true in the individual Rust project.
+
+## Rust utilities
+
+rslib/{process,io} contain some helpers for file and process operations,
+which provide better error messages/context and some ergonomics. Use them
+when possible.
+
+## Rust error handling
+
+in rslib, use error/mod.rs's AnkiError/Result and snafu. In our other Rust modules, prefer anyhow + additional context where appropriate. Unwrapping
+in build scripts/tests is fine.