# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## Project Overview

A statically-linked Zig binary that extracts highlights from Kobo e-reader SQLite databases. The project builds for both x86_64 (development) and ARM (target Kobo device).

## Build Commands

### Local development (x86_64)
```bash
zig build
./zig-out/bin/kb_exfiltrator local-dev.sqlite
```

### Run with arguments
```bash
zig build run -- path/to/database.sqlite
```

### Testing
```bash
zig build test
```

### For Kobo (ARM target)
```bash
./build-kobo.sh
# or manually:
zig build -Dtarget=arm-linux-musleabihf -Doptimize=ReleaseSmall
```

The ARM build creates `kb_exfiltrator-kobo-arm` in the project root.

## Architecture

### Module Structure

The project uses Zig's module system with two distinct modules:

- **kb_exfiltrator module** (`src/root.zig`): Library module exposing reusable functionality
- **Executable module** (`src/main.zig`): CLI entry point that imports the library module

The executable depends on the library module via the imports mechanism in build.zig:87-91.

### SQLite Integration

SQLite is vendored as an amalgamation build (vendor/sqlite-amalgamation-3480000/). The build.zig configuration:
- Links SQLite as a C source file (build.zig:87-93)
- Compiles with `SQLITE_THREADSAFE=0` (no threading, smaller binary)
- Compiles with `SQLITE_OMIT_LOAD_EXTENSION` (security)
- Uses `@cImport` in main.zig:2-4 to import C headers

### Static Linking

The binary is fully statically linked:
- Uses musl libc for ARM target (`arm-linux-musleabihf`)
- SQLite compiled directly into the binary
- No external dependencies required on target device

### Database Schema

The program queries the Kobo `Bookmark` table:
- `Text`: The highlighted text (non-NULL indicates a highlight)
- `Annotation`: User's notes on the highlight (nullable)
- `DateCreated`: Timestamp
- `ContentID`: Book identifier

Query implementation: src/main.zig:33-42

### Build System Details

The build.zig uses Zig's build graph system:
- Target and optimization are configurable via CLI (`-Dtarget`, `-Doptimize`)
- The executable step (build.zig:60-84) creates the root module and wires dependencies
- Tests are split into module tests and executable tests (build.zig:132-154)
- Both test suites run in parallel when executing `zig build test`

## Requirements

- Zig 0.15.2 or later (specified in build.zig.zon:28)