fix env variable load and subst order

source/src/utils/ordered_env.hpp

@@ -0,0 +1,64 @@
+#ifndef ORDERED_ENV_HPP
+#define ORDERED_ENV_HPP
+
+#include <vector>
+#include <string>
+#include <utility>
+#include <algorithm>
+
+namespace dropshell {
+
+// Type alias for insertion-ordered environment variables
+using ordered_env_vars = std::vector<std::pair<std::string, std::string>>;
+
+// Helper functions for working with ordered_env_vars like a map
+
+// Find a variable by key (returns iterator)
+inline auto find_var(ordered_env_vars& vars, const std::string& key) {
+    return std::find_if(vars.begin(), vars.end(),
+        [&](const auto& p) { return p.first == key; });
+}
+
+inline auto find_var(const ordered_env_vars& vars, const std::string& key) {
+    return std::find_if(vars.begin(), vars.end(),
+        [&](const auto& p) { return p.first == key; });
+}
+
+// Get a variable value (returns empty string if not found)
+inline std::string get_var(const ordered_env_vars& vars, const std::string& key) {
+    auto it = find_var(vars, key);
+    return (it != vars.end()) ? it->second : "";
+}
+
+// Set a variable (updates if exists, appends if new)
+inline void set_var(ordered_env_vars& vars, const std::string& key, const std::string& value) {
+    auto it = find_var(vars, key);
+    if (it != vars.end()) {
+        it->second = value;
+    } else {
+        vars.emplace_back(key, value);
+    }
+}
+
+// Check if a variable exists
+inline bool has_var(const ordered_env_vars& vars, const std::string& key) {
+    return find_var(vars, key) != vars.end();
+}
+
+// Merge variables from another ordered_env_vars (appends new, skips existing)
+inline void merge_vars(ordered_env_vars& dest, const ordered_env_vars& src) {
+    for (const auto& [key, value] : src) {
+        if (!has_var(dest, key)) {
+            dest.emplace_back(key, value);
+        }
+    }
+}
+
+// Clear all variables
+inline void clear_vars(ordered_env_vars& vars) {
+    vars.clear();
+}
+
+} // namespace dropshell
+
+#endif