Added:

- `build.kind = "efi"` — UEFI PE32+ executable support. Links with `-shared -nostdlib -Wl,-dll -Wl,--subsystem,10`, output via `efi_path()` with `.efi` extension, rejected by `dcr run`.
- `build.kind = "elf"` — bare-metal ELF executable support. Uses `elf_path()` output path, rejected by `dcr run`, no extra linker flags.

Fixed:

- `dcr run` with `--target` or `build.target` now correctly finds the binary in the arch-specific target directory.
- `dcr run` checks profile-specific `build.{profile}.kind` before rejecting library builds (previously only checked `build.kind`).
- `dcr clean` now reads `build.target` from `dcr.toml` when no `--target` flag is given.
- Linux: target directory is now consistent — `target/<arch>-unknown-linux-gnu/<profile>/` (no stale `target/<profile>/`).
- `dcr.lock` is now populated with all resolved dependencies (registry, path, git) instead of being always empty.
- Git dependencies are now properly recognized and recorded in `dcr.lock`.
- `is_registry_dep` correctly identifies version-based registry dependency tables (`{ version = "..." }`) and rejects tables with unknown keys.
- `dcr test` accepts `--debug`/`--release` flags (defaults to `debug` profile instead of always `release`).
- Build fingerprint cache (`build_cache_path`) now includes `target_dir` — different targets no longer share a single cache entry.
- `object_path` no longer hardcodes the `src/` prefix — works correctly with custom `build.roots` (e.g. `roots = ["lib"]`).
- `dcr update` now generates `.exe` candidates for all Windows targets, not just `x86_64-pc-windows-msvc`.
- Compiler existence is verified before starting the build (clear error if compiler is not found in PATH).
- Consolidated duplicate `OUTPUT_MUTEX` definitions — MSVC backend now uses the shared mutex from `common.rs`.
- Registry cache root directory is created if missing (prevents cryptic errors when `~/.dcr/` does not exist).

src/core/builder/common.rs

@@ -5,6 +5,10 @@ use std::sync::{Mutex, OnceLock};
 
 static OUTPUT_MUTEX: OnceLock<Mutex<()>> = OnceLock::new();
 
+pub fn get_output_lock() -> &'static Mutex<()> {
+    OUTPUT_MUTEX.get_or_init(|| Mutex::new(()))
+}
+
 pub fn collect_sources(
     roots: &[PathBuf],
     extensions: &[&str],
@@ -230,10 +234,16 @@ pub fn normalize_source_path(path: &Path) -> String {
 
 pub fn object_path(obj_dir: &Path, source: &str, obj_ext: &str) -> String {
     let src_path = Path::new(source);
-    let rel = src_path
-        .strip_prefix("./src")
-        .or_else(|_| src_path.strip_prefix("src"))
-        .unwrap_or(src_path);
+    let stripped = src_path.strip_prefix("./").unwrap_or(src_path);
+    let rel = stripped
+        .components()
+        .skip(1)
+        .collect::<std::path::PathBuf>();
+    let rel = if rel.components().next().is_some() {
+        rel
+    } else {
+        stripped.to_path_buf()
+    };
     let mut out = obj_dir.join(rel);
     out.set_extension(obj_ext.trim_start_matches('.'));
     out.to_string_lossy().to_string()

src/core/builder/gas.rs

@@ -18,7 +18,10 @@ pub fn build(ctx: &BuildContext) -> Result<f64, String> {
     };
     let start_time = Instant::now();
     let sources = collect_sources(ctx)?;
-    let obj_dir = Path::new("./target").join(ctx.profile).join("obj");
+    let obj_dir = match ctx.target_dir {
+        Some(dir) => Path::new(dir).join("obj"),
+        None => Path::new("./target").join(ctx.profile).join("obj"),
+    };
     let objects = build_objects(assembler, &sources, &obj_dir, ctx, "o")?;
 
     if ctx.kind == "staticlib" {
@@ -80,6 +83,8 @@ pub fn build(ctx: &BuildContext) -> Result<f64, String> {
 
     let out_path = if ctx.kind == "sharedlib" {
         platform::shared_lib_path(ctx.profile, &final_name, ctx.target_dir)
+    } else if ctx.kind == "elf" {
+        platform::elf_path(ctx.profile, &final_name, ctx.target_dir)
     } else {
         platform::bin_path(ctx.profile, &final_name, ctx.target_dir)
     };

src/core/builder/mod.rs

@@ -33,6 +33,12 @@ pub struct BuildContext<'a> {
 
 pub fn build(ctx: &BuildContext) -> Result<f64, String> {
     let compiler = ctx.compiler.to_lowercase();
+    if !check_compiler_exists(ctx.compiler) {
+        return Err(format!(
+            "Compiler not found: {}. Make sure it is installed and available in PATH.",
+            ctx.compiler
+        ));
+    }
     if compiler.contains("clang-cl") {
         return msvc::build(ctx);
     }
@@ -48,6 +54,14 @@ pub fn build(ctx: &BuildContext) -> Result<f64, String> {
     unix_cc::build(ctx)
 }
 
+fn check_compiler_exists(compiler: &str) -> bool {
+    let name = if compiler.is_empty() { "cc" } else { compiler };
+    std::process::Command::new(name)
+        .arg("--version")
+        .output()
+        .is_ok()
+}
+
 pub fn collect_sources(ctx: &BuildContext) -> Result<Vec<String>, String> {
     let compiler = ctx.compiler.to_lowercase();
     if compiler.contains("clang-cl") || compiler == "cl" || compiler.contains("msvc") {

src/core/builder/msvc.rs

@@ -18,7 +18,10 @@ pub fn build(ctx: &BuildContext) -> Result<f64, String> {
     }
     let start_time = Instant::now();
     let sources = collect_sources(ctx)?;
-    let obj_dir = Path::new("./target").join(ctx.profile).join("obj");
+    let obj_dir = match ctx.target_dir {
+        Some(dir) => Path::new(dir).join("obj"),
+        None => Path::new("./target").join(ctx.profile).join("obj"),
+    };
     let objects = build_objects(compiler, &sources, &obj_dir, ctx, "obj")?;
 
     if ctx.kind == "staticlib" {
@@ -92,6 +95,8 @@ pub fn build(ctx: &BuildContext) -> Result<f64, String> {
     }
     let out_path = if ctx.kind == "sharedlib" {
         platform::shared_lib_path(ctx.profile, ctx.project_name, ctx.target_dir)
+    } else if ctx.kind == "elf" {
+        platform::elf_path(ctx.profile, ctx.project_name, ctx.target_dir)
     } else {
         platform::bin_path(ctx.profile, ctx.project_name, ctx.target_dir)
     };
@@ -185,8 +190,6 @@ fn default_flags(profile: &str) -> &'static [&'static str] {
     }
 }
 
-static OUTPUT_MUTEX: std::sync::Mutex<()> = std::sync::Mutex::new(());
-
 fn build_objects(
     compiler: &str,
     sources: &[String],
@@ -282,7 +285,7 @@ fn build_object(
         }
     }
 
-    let _lock = OUTPUT_MUTEX.lock().unwrap();
+    let _lock = common::get_output_lock().lock().unwrap();
 
     if !output.status.success() {
         eprint!("{}", clean_stdout);

src/core/builder/nasm.rs

@@ -18,7 +18,10 @@ pub fn build(ctx: &BuildContext) -> Result<f64, String> {
     };
     let start_time = Instant::now();
     let sources = collect_sources(ctx)?;
-    let obj_dir = Path::new("./target").join(ctx.profile).join("obj");
+    let obj_dir = match ctx.target_dir {
+        Some(dir) => Path::new(dir).join("obj"),
+        None => Path::new("./target").join(ctx.profile).join("obj"),
+    };
     let objects = build_objects(assembler, &sources, &obj_dir, ctx, "o")?;
 
     if ctx.kind == "staticlib" {
@@ -80,6 +83,8 @@ pub fn build(ctx: &BuildContext) -> Result<f64, String> {
 
     let out_path = if ctx.kind == "sharedlib" {
         platform::shared_lib_path(ctx.profile, &final_name, ctx.target_dir)
+    } else if ctx.kind == "elf" {
+        platform::elf_path(ctx.profile, &final_name, ctx.target_dir)
     } else {
         platform::bin_path(ctx.profile, &final_name, ctx.target_dir)
     };

src/core/builder/unix_cc.rs

@@ -20,7 +20,10 @@ pub fn build(ctx: &BuildContext) -> Result<f64, String> {
         ctx.exclude_dirs,
         ctx.include_paths,
     )?;
-    let obj_dir = Path::new("./target").join(ctx.profile).join("obj");
+    let obj_dir = match ctx.target_dir {
+        Some(dir) => Path::new(dir).join("obj"),
+        None => Path::new("./target").join(ctx.profile).join("obj"),
+    };
     let objects = build_objects(compiler, &sources, &obj_dir, ctx, "o")?;
 
     if ctx.kind == "staticlib" {
@@ -51,6 +54,12 @@ pub fn build(ctx: &BuildContext) -> Result<f64, String> {
             cmd.arg("-shared");
         }
     }
+    if ctx.kind == "efi" {
+        cmd.arg("-shared");
+        cmd.arg("-nostdlib");
+        cmd.arg("-Wl,-dll");
+        cmd.arg("-Wl,--subsystem,10");
+    }
     for obj in &objects {
         cmd.arg(obj);
     }
@@ -73,6 +82,10 @@ pub fn build(ctx: &BuildContext) -> Result<f64, String> {
 
     let out_path = if ctx.kind == "sharedlib" {
         platform::shared_lib_path(ctx.profile, &final_name, ctx.target_dir)
+    } else if ctx.kind == "efi" {
+        platform::efi_path(ctx.profile, &final_name, ctx.target_dir)
+    } else if ctx.kind == "elf" {
+        platform::elf_path(ctx.profile, &final_name, ctx.target_dir)
     } else {
         platform::bin_path(ctx.profile, &final_name, ctx.target_dir)
     };

src/core/config.rs

@@ -10,6 +10,7 @@ const DEFAULT_LANGUAGE: &str = "c";
 const DEFAULT_STANDARD: &str = "c11";
 const DEFAULT_COMPILER: &str = "clang";
 const DEFAULT_KIND: &str = "bin";
+const VALID_KINDS: &[&str] = &["bin", "staticlib", "sharedlib", "efi", "elf"];
 
 #[derive(Debug)]
 pub enum ConfigError {
@@ -242,7 +243,7 @@ impl Config {
         validate_toolchain(self.typed.toolchain.as_ref())?;
         if let Some(kind) = &self.typed.build.kind {
             let kind = kind.trim();
-            if !kind.is_empty() && kind != "bin" && kind != "staticlib" && kind != "sharedlib" {
+            if !kind.is_empty() && !VALID_KINDS.contains(&kind) {
                 return Err(ConfigError::Invalid("build.kind is invalid".into()));
             }
         }
@@ -410,7 +411,7 @@ impl Config {
         }
         if let Some(kind) = table.get("kind").and_then(|v| v.as_str()) {
             let kind = kind.trim();
-            if !kind.is_empty() && kind != "bin" && kind != "staticlib" && kind != "sharedlib" {
+            if !kind.is_empty() && !VALID_KINDS.contains(&kind) {
                 return Err(ConfigError::Invalid(format!(
                     "build.{profile}.kind is invalid"
                 )));
@@ -919,14 +920,16 @@ mod tests {
 
     #[test]
     fn validate_valid_kinds() {
-        for kind in ["bin", "staticlib", "sharedlib"] {
-            let dir = temp_dir(&format!("kind_{kind}"));
-            let content = format!(
+        for &kind in VALID_KINDS {
+            let dir = temp_dir("valid_kind");
+            let toml = format!(
                 "[package]\nname = \"test\"\nversion = \"0.1.0\"\n\n[build]\nlanguage = \"c\"\nstandard = \"c11\"\ncompiler = \"clang\"\nkind = \"{kind}\"\n\n[dependencies]\n"
             );
-            let path = write_toml_file(&dir, &content);
-            let result = Config::open(&path.to_string_lossy());
-            assert!(result.is_ok(), "kind '{kind}' should be valid");
+            let path = write_toml_file(&dir, &toml);
+            assert!(
+                Config::open(&path.to_string_lossy()).is_ok(),
+                "kind '{kind}' should be valid"
+            );
         }
     }
 

src/core/deps/mod.rs

@@ -5,8 +5,20 @@ pub mod register;
 
 use crate::core::config::Config;
 use crate::core::deps::common::ResolvedDeps;
+use crate::core::deps::lock::{DepLock, write_lock};
 use std::path::Path;
 
+fn dep_version(path: &Path) -> String {
+    Config::open(&path.join("dcr.toml").to_string_lossy())
+        .ok()
+        .and_then(|c| {
+            c.get("package.version")
+                .and_then(|v| v.as_str())
+                .map(|s| s.to_string())
+        })
+        .unwrap_or_default()
+}
+
 pub fn resolve_deps(
     config: &Config,
     _profile: &str,
@@ -26,7 +38,7 @@ pub fn resolve_deps(
         .to_string();
 
     let deps_table = config.get("dependencies").and_then(|v| v.as_table());
-    let lock_packages = Vec::new();
+    let mut lock_packages: Vec<DepLock> = Vec::new();
 
     if let Some(deps) = deps_table {
         for (name, value) in deps {
@@ -45,6 +57,23 @@ pub fn resolve_deps(
                         .to_string(),
                 );
                 resolved.libs.push(name.clone());
+
+                lock_packages.push(DepLock {
+                    name: name.clone(),
+                    version: pkg_info
+                        .get("version")
+                        .and_then(|v| v.as_str())
+                        .unwrap_or("")
+                        .to_string(),
+                    checksum: String::new(),
+                    source: format!(
+                        "registry+{}",
+                        pkg_info
+                            .get("registry_url")
+                            .and_then(|v| v.as_str())
+                            .unwrap_or("https://dcr-registry.pages.dev")
+                    ),
+                });
             } else if let Some(path) = path_dep_path(value) {
                 let dep_root = project_root.join(path);
                 if let Some(table) = value.as_table() {
@@ -86,11 +115,25 @@ pub fn resolve_deps(
                     push_default_lib_dirs(&mut resolved.lib_dirs, &dep_root);
                     resolved.libs.push(name.clone());
                 }
+
+                lock_packages.push(DepLock {
+                    name: name.clone(),
+                    version: dep_version(&dep_root),
+                    checksum: String::new(),
+                    source: format!("path+{}", dep_root.display()),
+                });
+            } else if let Some(git_info) = git_dep(value) {
+                lock_packages.push(DepLock {
+                    name: name.clone(),
+                    version: git_info.version.unwrap_or_default(),
+                    checksum: String::new(),
+                    source: format!("git+{}", git_info.url),
+                });
             }
         }
     }
 
-    crate::core::deps::lock::write_lock(
+    write_lock(
         project_root,
         &project_name,
         &project_version,
@@ -100,6 +143,24 @@ pub fn resolve_deps(
     Ok(resolved)
 }
 
+struct GitDep<'a> {
+    url: &'a str,
+    version: Option<String>,
+}
+
+fn git_dep(value: &toml::Value) -> Option<GitDep<'_>> {
+    if let Some(table) = value.as_table()
+        && let Some(url) = table.get("git").and_then(|v| v.as_str())
+    {
+        let version = table
+            .get("version")
+            .and_then(|v| v.as_str())
+            .map(|s| s.to_string());
+        return Some(GitDep { url, version });
+    }
+    None
+}
+
 fn path_dep_path(value: &toml::Value) -> Option<&str> {
     if let Some(table) = value.as_table() {
         return table.get("path").and_then(|v| v.as_str());

src/core/deps/register.rs

@@ -51,10 +51,18 @@ pub fn get_index_path() -> PathBuf {
 }
 
 pub fn get_registry_cache_root() -> PathBuf {
-    get_index_path()
-        .parent()
-        .map(Path::to_path_buf)
-        .unwrap_or_else(|| PathBuf::from("."))
+    let index_path = get_index_path();
+    if let Some(parent) = index_path.parent() {
+        if parent.exists() {
+            return parent.to_path_buf();
+        }
+        if let Err(e) = std::fs::create_dir_all(parent) {
+            eprintln!("Warning: failed to create registry cache directory: {e}");
+        }
+        parent.to_path_buf()
+    } else {
+        PathBuf::from(".")
+    }
 }
 
 pub fn package_root_from_registry_info(pkg_info: &JsonValue) -> Result<PathBuf, String> {
@@ -124,12 +132,16 @@ pub fn is_registry_dep(value: &TomlValue) -> bool {
         return !is_path_like_string(raw) && !is_git_like_string(raw);
     }
     if let Some(table) = value.as_table() {
-        return !table.contains_key("git")
-            && !table.contains_key("path")
-            && !table.contains_key("url")
-            && !table.contains_key("version");
+        if table.contains_key("git") || table.contains_key("path") || table.contains_key("url") {
+            return false;
+        }
+        table.contains_key("version")
+            || table.contains_key("features")
+            || table.contains_key("optional")
+            || table.contains_key("registry")
+    } else {
+        false
     }
-    false
 }
 
 pub fn path_from_string_dep(value: &TomlValue) -> Option<&str> {