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/platform/linux.rs

@@ -12,14 +12,44 @@ pub fn bin_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
 pub fn lib_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
     match target_dir {
         Some(dir) => format!("{}/lib{}.a", dir.trim_end_matches('/'), name),
-        None => format!("./target/{profile}/lib{name}.a"),
+        None => {
+            let arch = std::env::consts::ARCH;
+            let target = format!("{arch}-unknown-linux-gnu");
+            format!("./target/{target}/{profile}/lib{name}.a")
+        }
+    }
+}
+
+pub fn elf_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
+    match target_dir {
+        Some(dir) => format!("{}/{}", dir.trim_end_matches('/'), name),
+        None => {
+            let arch = std::env::consts::ARCH;
+            let target = format!("{arch}-unknown-linux-gnu");
+            format!("./target/{target}/{profile}/{name}")
+        }
+    }
+}
+
+pub fn efi_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
+    match target_dir {
+        Some(dir) => format!("{}/{}.efi", dir.trim_end_matches('/'), name),
+        None => {
+            let arch = std::env::consts::ARCH;
+            let target = format!("{arch}-unknown-linux-gnu");
+            format!("./target/{target}/{profile}/{name}.efi")
+        }
     }
 }
 
 pub fn shared_lib_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
     match target_dir {
         Some(dir) => format!("{}/lib{}.so", dir.trim_end_matches('/'), name),
-        None => format!("./target/{profile}/lib{name}.so"),
+        None => {
+            let arch = std::env::consts::ARCH;
+            let target = format!("{arch}-unknown-linux-gnu");
+            format!("./target/{target}/{profile}/lib{name}.so")
+        }
     }
 }
 
@@ -53,10 +83,9 @@ mod tests {
 
     #[test]
     fn lib_path_default() {
-        assert_eq!(
-            lib_path("debug", "mylib", None),
-            "./target/debug/libmylib.a"
-        );
+        let arch = std::env::consts::ARCH;
+        let expected = format!("./target/{arch}-unknown-linux-gnu/debug/libmylib.a");
+        assert_eq!(lib_path("debug", "mylib", None), expected);
     }
 
     #[test]
@@ -66,10 +95,9 @@ mod tests {
 
     #[test]
     fn shared_lib_path_default() {
-        assert_eq!(
-            shared_lib_path("debug", "mylib", None),
-            "./target/debug/libmylib.so"
-        );
+        let arch = std::env::consts::ARCH;
+        let expected = format!("./target/{arch}-unknown-linux-gnu/debug/libmylib.so");
+        assert_eq!(shared_lib_path("debug", "mylib", None), expected);
     }
 
     #[test]

src/platform/macos.rs

@@ -12,6 +12,20 @@ pub fn lib_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
     }
 }
 
+pub fn elf_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
+    match target_dir {
+        Some(dir) => format!("{}/{}", dir.trim_end_matches('/'), name),
+        None => format!("./target/{profile}/{name}"),
+    }
+}
+
+pub fn efi_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
+    match target_dir {
+        Some(dir) => format!("{}/{}.efi", dir.trim_end_matches('/'), name),
+        None => format!("./target/{profile}/{name}.efi"),
+    }
+}
+
 pub fn shared_lib_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
     match target_dir {
         Some(dir) => format!("{}/lib{}.dylib", dir.trim_end_matches('/'), name),

src/platform/mod.rs

@@ -27,6 +27,50 @@ pub fn bin_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
     }
 }
 
+pub fn elf_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
+    #[cfg(target_os = "linux")]
+    {
+        linux::elf_path(profile, name, target_dir)
+    }
+    #[cfg(target_os = "macos")]
+    {
+        return macos::elf_path(profile, name, target_dir);
+    }
+    #[cfg(target_os = "windows")]
+    {
+        return windows::elf_path(profile, name, target_dir);
+    }
+    #[cfg(not(any(target_os = "linux", target_os = "macos", target_os = "windows")))]
+    {
+        match target_dir {
+            Some(dir) => format!("{}/{}", dir.trim_end_matches('/'), name),
+            None => format!("./target/{profile}/{name}"),
+        }
+    }
+}
+
+pub fn efi_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
+    #[cfg(target_os = "linux")]
+    {
+        linux::efi_path(profile, name, target_dir)
+    }
+    #[cfg(target_os = "macos")]
+    {
+        return macos::efi_path(profile, name, target_dir);
+    }
+    #[cfg(target_os = "windows")]
+    {
+        return windows::efi_path(profile, name, target_dir);
+    }
+    #[cfg(not(any(target_os = "linux", target_os = "macos", target_os = "windows")))]
+    {
+        match target_dir {
+            Some(dir) => format!("{}/{}.efi", dir.trim_end_matches('/'), name),
+            None => format!("./target/{profile}/{name}.efi"),
+        }
+    }
+}
+
 pub fn lib_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
     #[cfg(target_os = "linux")]
     {

src/platform/windows.rs

@@ -12,6 +12,20 @@ pub fn lib_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
     }
 }
 
+pub fn elf_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
+    match target_dir {
+        Some(dir) => format!("{}/{}.exe", dir.trim_end_matches('/'), name),
+        None => format!("./target/{profile}/{name}.exe"),
+    }
+}
+
+pub fn efi_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
+    match target_dir {
+        Some(dir) => format!("{}/{}.efi", dir.trim_end_matches('/'), name),
+        None => format!("./target/{profile}/{name}.efi"),
+    }
+}
+
 pub fn shared_lib_path(profile: &str, name: &str, target_dir: Option<&str>) -> String {
     match target_dir {
         Some(dir) => format!("{}/{}.dll", dir.trim_end_matches('/'), name),