refactor(hm-dsl-engine): Replace stringly-typed run() mode ("list"/"render") with an internal enum

Author: markovejnovic

crates/hm-dsl-engine/src/ts_engine.rs

@@ -96,6 +96,26 @@ impl Drop for SymlinkCleanup {
     }
 }
 
+/// The operation the embedded JS runner should perform.
+///
+/// Modeled as a closed enum so the dispatch is exhaustive and typo-proof at
+/// compile time; the wire string lives in exactly one place (`as_arg`).
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum RunMode {
+    List,
+    Render,
+}
+
+impl RunMode {
+    /// The CLI argument passed to the JS runner for this mode.
+    fn as_arg(self) -> &'static str {
+        match self {
+            Self::List => "list",
+            Self::Render => "render",
+        }
+    }
+}
+
 #[derive(Debug)]
 pub struct SubprocessTsEngine {
     runtime: JsRuntime,
@@ -154,7 +174,7 @@ impl SubprocessTsEngine {
         }
     }
 
-    async fn run(&self, project_dir: &Path, mode: &str, slug: Option<&str>) -> Result<String> {
+    async fn run(&self, project_dir: &Path, mode: RunMode, slug: Option<&str>) -> Result<String> {
         let tmp = self.setup_temp()?;
         let runner_path = tmp.path().join("runner.mjs");
 
@@ -218,7 +238,7 @@ impl SubprocessTsEngine {
             }
         }
 
-        cmd.arg(project_dir).arg(mode);
+        cmd.arg(project_dir).arg(mode.as_arg());
 
         if let Some(s) = slug {
             cmd.arg(s);
@@ -247,7 +267,7 @@ impl SubprocessTsEngine {
 impl DslEngine for SubprocessTsEngine {
     async fn list_pipelines(&self, project_dir: &Path) -> Result<Vec<PipelineMeta>> {
         let stdout = self
-            .run(project_dir, "list", None)
+            .run(project_dir, RunMode::List, None)
             .await
             .context("listing pipelines via JS runtime")?;
 
@@ -257,7 +277,7 @@ impl DslEngine for SubprocessTsEngine {
     }
 
     async fn render_pipeline_json(&self, project_dir: &Path, slug: &str) -> Result<String> {
-        self.run(project_dir, "render", Some(slug))
+        self.run(project_dir, RunMode::Render, Some(slug))
             .await
             .context("rendering pipeline via JS runtime")
     }