Traverse upwards for single context projects

rewatch/src/helpers.rs

@@ -154,12 +154,63 @@ pub fn try_package_path(
     } else if path_from_root.exists() {
         Ok(path_from_root)
     } else {
+        // As a last resort, when we're in a Single project context, traverse upwards
+        // starting from the parent of the package root (package_config.path.parent().parent())
+        // and probe each ancestor's node_modules for the dependency. This covers hoisted
+        // workspace setups when building a package standalone.
+        if project_context.monorepo_context.is_none() {
+            match package_config.path.parent().and_then(|p| p.parent()) {
+                Some(start_dir) => {
+                    return find_dep_in_upward_node_modules(start_dir, package_name);
+                }
+                None => {
+                    log::debug!(
+                        "try_package_path: cannot compute start directory for upward traversal from '{}'",
+                        package_config.path.to_string_lossy()
+                    );
+                }
+            }
+        }
+
         Err(anyhow!(
             "The package \"{package_name}\" is not found (are node_modules up-to-date?)..."
         ))
     }
 }
 
+fn find_dep_in_upward_node_modules(start_dir: &Path, package_name: &str) -> anyhow::Result<PathBuf> {
+    log::debug!(
+        "try_package_path: falling back to upward traversal for '{}' starting at '{}'",
+        package_name,
+        start_dir.to_string_lossy()
+    );
+
+    let mut current = Some(start_dir);
+    while let Some(dir) = current {
+        let candidate = package_path(dir, package_name);
+        log::debug!("try_package_path: checking '{}'", candidate.to_string_lossy());
+        if candidate.exists() {
+            log::debug!(
+                "try_package_path: found '{}' at '{}' via upward traversal",
+                package_name,
+                candidate.to_string_lossy()
+            );
+            return Ok(candidate);
+        }
+        current = dir.parent();
+    }
+    log::debug!(
+        "try_package_path: no '{}' found during upward traversal from '{}'",
+        package_name,
+        start_dir.to_string_lossy()
+    );
+    Err(anyhow!(
+        "try_package_path: upward traversal did not find '{}' starting at '{}'",
+        package_name,
+        start_dir.to_string_lossy()
+    ))
+}
+
 pub fn get_abs_path(path: &Path) -> PathBuf {
     let abs_path_buf = PathBuf::from(path);