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/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"
+            );
         }
     }