feat: codebase mapper with CODEBASE.md generation (#190)

- Add scan_project Rust command that walks the directory tree and detects project type
- Add CODEBASE as a managed ProjectFile type alongside PROJECT/REQUIREMENTS/ROADMAP/STATE
- Add mapCodebase() store function that scans and sends an analysis prompt to Claude
- Add CODEBASE tab to ProjectContextPanel with Map/Remap buttons and auto-reload on idle
- Update PROJECT_CONTEXT_SYSTEM_ADDENDUM to include CODEBASE.md reference

src-tauri/src/commands.rs

@@ -2337,6 +2337,160 @@ pub async fn get_mcp_server_details(name: String) -> Result<String, String> {
     }
 }
 
+// ==================== Codebase Mapper ====================
+
+/// Directories to skip when scanning (always ignored regardless of .gitignore)
+const SCAN_SKIP_DIRS: &[&str] = &[
+    ".git",
+    "node_modules",
+    "target",
+    ".next",
+    "dist",
+    "build",
+    "out",
+    "__pycache__",
+    ".cache",
+    ".pytest_cache",
+    "vendor",
+    ".idea",
+    ".vscode",
+    "coverage",
+    ".nyc_output",
+    "venv",
+    ".venv",
+    "env",
+    ".tox",
+];
+
+/// Files that indicate the project type
+const PROJECT_MARKERS: &[(&str, &str)] = &[
+    ("Cargo.toml", "Rust"),
+    ("package.json", "Node.js"),
+    ("pyproject.toml", "Python"),
+    ("requirements.txt", "Python"),
+    ("go.mod", "Go"),
+    ("pom.xml", "Java (Maven)"),
+    ("build.gradle", "Java (Gradle)"),
+    ("Gemfile", "Ruby"),
+    ("composer.json", "PHP"),
+    ("*.csproj", "C#/.NET"),
+    ("CMakeLists.txt", "C/C++ (CMake)"),
+    ("Makefile", "C/C++"),
+];
+
+#[derive(Debug, Serialize)]
+pub struct ProjectScan {
+    pub working_dir: String,
+    pub file_tree: String,
+    pub detected_type: String,
+    pub key_files: Vec<String>,
+}
+
+/// Recursively build a file tree string, respecting skip dirs, up to `max_depth` levels.
+fn build_file_tree(
+    dir: &std::path::Path,
+    prefix: &str,
+    depth: usize,
+    max_depth: usize,
+    lines: &mut Vec<String>,
+) {
+    if depth > max_depth {
+        lines.push(format!("{}...", prefix));
+        return;
+    }
+
+    let Ok(entries) = std::fs::read_dir(dir) else {
+        return;
+    };
+
+    let mut items: Vec<std::fs::DirEntry> = entries
+        .filter_map(|e| e.ok())
+        .collect();
+    items.sort_by_key(|e| {
+        let name = e.file_name().to_string_lossy().to_lowercase();
+        // Sort: hidden last, directories first
+        let is_hidden = name.starts_with('.');
+        let is_dir = e.path().is_dir();
+        (is_hidden, !is_dir, name)
+    });
+
+    let count = items.len();
+    for (i, entry) in items.iter().enumerate() {
+        let name = entry.file_name().to_string_lossy().to_string();
+        let is_last = i == count - 1;
+        let connector = if is_last { "└── " } else { "├── " };
+        let child_prefix = if is_last {
+            format!("{}    ", prefix)
+        } else {
+            format!("{}│   ", prefix)
+        };
+
+        let path = entry.path();
+        if path.is_dir() {
+            if SCAN_SKIP_DIRS.contains(&name.as_str()) {
+                lines.push(format!("{}{}{}/ (skipped)", prefix, connector, name));
+                continue;
+            }
+            lines.push(format!("{}{}{}/", prefix, connector, name));
+            build_file_tree(&path, &child_prefix, depth + 1, max_depth, lines);
+        } else {
+            lines.push(format!("{}{}{}", prefix, connector, name));
+        }
+    }
+}
+
+#[tauri::command]
+pub async fn scan_project(working_dir: String) -> Result<ProjectScan, String> {
+    let dir_path = std::path::Path::new(&working_dir);
+
+    if !dir_path.exists() {
+        return Err(format!("Directory does not exist: {}", working_dir));
+    }
+    if !dir_path.is_dir() {
+        return Err(format!("Path is not a directory: {}", working_dir));
+    }
+
+    // Detect project type by checking for marker files
+    let mut detected_type = "Unknown".to_string();
+    let mut key_files: Vec<String> = Vec::new();
+
+    for (marker, project_type) in PROJECT_MARKERS {
+        let marker_path = dir_path.join(marker);
+        if marker_path.exists() {
+            if detected_type == "Unknown" {
+                detected_type = project_type.to_string();
+            }
+            key_files.push(marker.to_string());
+        }
+    }
+
+    // Also collect other notable root-level files
+    let notable_root_files = &[
+        "README.md", "CLAUDE.md", "LICENSE", ".env.example",
+        "docker-compose.yml", "Dockerfile", ".github",
+        "tsconfig.json", "vitest.config.ts", "eslint.config.js",
+        "check-all.sh", "tauri.conf.json",
+    ];
+    for file in notable_root_files {
+        let file_path = dir_path.join(file);
+        if file_path.exists() && !key_files.contains(&file.to_string()) {
+            key_files.push(file.to_string());
+        }
+    }
+
+    // Build file tree (max 4 levels deep)
+    let mut lines: Vec<String> = vec![format!("{}/", working_dir)];
+    build_file_tree(dir_path, "", 0, 4, &mut lines);
+    let file_tree = lines.join("\n");
+
+    Ok(ProjectScan {
+        working_dir,
+        file_tree,
+        detected_type,
+        key_files,
+    })
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src-tauri/src/lib.rs

@@ -220,6 +220,7 @@ pub fn run() {
             save_draft,
             delete_draft,
             delete_all_drafts,
+            scan_project,
         ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");