feat: add Cub cook autodetect strategy

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

local/recipes/system/cub/source/cub-lib/src/cook.rs

@@ -6,6 +6,13 @@ use std::process::Command;
 use crate::error::CubError;
 use crate::sandbox::SandboxConfig;
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum CookStrategy {
+    Require,
+    Skip,
+    AutoDetect,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct CookResult {
     pub pkgar_path: PathBuf,
@@ -18,12 +25,31 @@ pub fn cook_recipe(
     target: &str,
     repo_dir: &Path,
 ) -> Result<CookResult, CubError> {
-    let repo_binary = find_repo_binary_with_hint(repo_dir).ok_or_else(|| {
-        CubError::BuildFailed(
-            "repo binary not found. Build tools must be installed inside Red Bear OS to cook recipes."
-                .to_string(),
-        )
-    })?;
+    match cook_or_skip(recipe_dir, target, repo_dir, CookStrategy::Require)? {
+        Some(result) => Ok(result),
+        None => Err(CubError::BuildFailed(
+            "cooking was skipped despite CookStrategy::Require".to_string(),
+        )),
+    }
+}
+
+pub fn cook_or_skip(
+    recipe_dir: &Path,
+    target: &str,
+    repo_dir: &Path,
+    strategy: CookStrategy,
+) -> Result<Option<CookResult>, CubError> {
+    let repo_binary = match strategy {
+        CookStrategy::Require => Some(
+            find_repo_binary_with_hint(repo_dir).ok_or_else(cook_unavailable_with_message_error)?,
+        ),
+        CookStrategy::Skip => return Ok(None),
+        CookStrategy::AutoDetect => find_repo_binary_with_hint(repo_dir),
+    };
+
+    let Some(repo_binary) = repo_binary else {
+        return Ok(None);
+    };
 
     let mut sandbox = SandboxConfig::new(recipe_dir);
     sandbox.target = target.to_string();
@@ -56,11 +82,11 @@ pub fn cook_recipe(
     let toml_path = find_repo_artifact(repo_dir, target, &recipe_name, "toml")?
         .unwrap_or_else(|| recipe_dir.join("recipe.toml"));
 
-    Ok(CookResult {
+    Ok(Some(CookResult {
         pkgar_path,
         toml_path,
         stage_dir: sandbox.stage_dir,
-    })
+    }))
 }
 
 pub fn is_repo_available() -> bool {
@@ -83,11 +109,37 @@ pub fn cook_available() -> Result<(), CubError> {
     }
 }
 
+pub fn cook_with_setup_instructions() -> String {
+    concat!(
+        "Build tools are not available in this environment. To cook recipes, you need:\n",
+        "1. The Red Bear OS build toolchain (cross-compiler for x86_64-unknown-redox)\n",
+        "2. The 'repo' cookbook binary in your PATH or at ./target/release/repo\n",
+        "\n",
+        "Until build tools are ported inside Red Bear OS, you can:\n",
+        "- Use 'cub -G <pkg>' to fetch and convert AUR packages to recipes\n",
+        "- Build packages on a Linux build host and transfer the .pkgar files\n",
+        "- Install pre-built packages directly with 'cub -S <pkg>'"
+    )
+    .to_string()
+}
+
+pub fn cook_available_with_message() -> Result<(), CubError> {
+    if is_repo_available() {
+        Ok(())
+    } else {
+        Err(cook_unavailable_with_message_error())
+    }
+}
+
 fn find_repo_binary_with_hint(repo_dir: &Path) -> Option<PathBuf> {
     let cwd = std::env::current_dir().ok();
     find_repo_binary_from(std::env::var_os("PATH"), cwd.as_deref(), Some(repo_dir))
 }
 
+fn cook_unavailable_with_message_error() -> CubError {
+    CubError::BuildFailed(cook_with_setup_instructions())
+}
+
 fn find_repo_binary_from(
     path_env: Option<OsString>,
     cwd: Option<&Path>,
@@ -244,7 +296,10 @@ fn render_command_failure(stdout: &[u8], stderr: &[u8]) -> String {
 
 #[cfg(test)]
 mod tests {
-    use super::{find_repo_binary, is_repo_available};
+    use super::{
+        cook_available_with_message, cook_or_skip, cook_with_setup_instructions,
+        find_repo_binary, is_repo_available, CookStrategy,
+    };
     use std::fs;
     use std::path::{Path, PathBuf};
     use std::sync::{Mutex, OnceLock};
@@ -356,6 +411,68 @@ mod tests {
         assert!(!is_repo_available());
     }
 
+    #[test]
+    fn test_cook_or_skip_returns_none_with_skip_strategy() {
+        let _guard = env_lock().lock().expect("lock env");
+        let temp = tempdir().expect("tempdir");
+        let cwd = temp.path().join("project");
+        fs::create_dir_all(&cwd).expect("create cwd dir");
+
+        let _env = TestEnvGuard::new(None, &cwd);
+
+        let result = cook_or_skip(
+            &temp.path().join("recipe"),
+            "x86_64-unknown-redox",
+            &temp.path().join("repo-root"),
+            CookStrategy::Skip,
+        )
+        .expect("skip strategy should succeed");
+
+        assert_eq!(result, None);
+    }
+
+    #[test]
+    fn test_cook_or_skip_returns_none_with_autodetect_when_repo_missing() {
+        let _guard = env_lock().lock().expect("lock env");
+        let temp = tempdir().expect("tempdir");
+        let cwd = temp.path().join("project");
+        fs::create_dir_all(&cwd).expect("create cwd dir");
+
+        let _env = TestEnvGuard::new(None, &cwd);
+
+        let result = cook_or_skip(
+            &temp.path().join("recipe"),
+            "x86_64-unknown-redox",
+            &temp.path().join("repo-root"),
+            CookStrategy::AutoDetect,
+        )
+        .expect("autodetect strategy should succeed when repo is missing");
+
+        assert_eq!(result, None);
+    }
+
+    #[test]
+    fn test_cook_available_with_message_returns_instructions() {
+        let _guard = env_lock().lock().expect("lock env");
+        let temp = tempdir().expect("tempdir");
+        let cwd = temp.path().join("project");
+        fs::create_dir_all(&cwd).expect("create cwd dir");
+
+        let _env = TestEnvGuard::new(None, &cwd);
+
+        let error = cook_available_with_message().expect_err("repo should be unavailable");
+        let message = error.to_string();
+
+        assert!(message.contains("Build tools are not available in this environment"));
+        assert!(message.contains("The Red Bear OS build toolchain"));
+        assert!(message.contains("'repo' cookbook binary"));
+    }
+
+    #[test]
+    fn test_cook_with_setup_instructions_is_nonempty() {
+        assert!(!cook_with_setup_instructions().trim().is_empty());
+    }
+
     fn create_executable(path: &Path) {
         fs::write(path, b"#!/bin/sh\nexit 0\n").expect("write repo binary");