feat: add cli execution previews

crates/localllm-cli/src/main.rs

@@ -478,14 +478,46 @@ fn execution_stub(contract: &ExecutionContract) -> ExecutionStub {
     }
 }
 
-fn execution_preview(_cli: &Cli, stub: &ExecutionStub) -> ExecutionPreview {
+fn execution_preview(cli: &Cli, stub: &ExecutionStub) -> ExecutionPreview {
     match stub {
         ExecutionStub::SummaryOnly { command } => ExecutionPreview::SummaryOnly {
             command: command.clone(),
         },
-        _ => ExecutionPreview::SummaryOnly {
-            command: "preview-unimplemented".to_owned(),
+        ExecutionStub::HttpRequest {
+            method,
+            path,
+            api_key_present,
+            body,
+        } => ExecutionPreview::HttpPreview {
+            method,
+            url: format!("{}{}", cli.server.trim_end_matches('/'), path),
+            api_key_present: *api_key_present,
+            body: body.clone(),
         },
+        ExecutionStub::LocalAction {
+            action,
+            target,
+            detail,
+        } => ExecutionPreview::LocalPreview {
+            action,
+            target: target.clone(),
+            effect: preview_effect(action, detail.as_deref()),
+        },
+    }
+}
+
+fn preview_effect(action: &str, detail: Option<&str>) -> String {
+    match (action, detail) {
+        ("scan_models_dir", _) => "discover available model files".to_owned(),
+        ("load_model", Some(detail)) => format!("load {}", detail),
+        ("configure_auth", Some(detail)) => format!("set {}", detail),
+        ("write_config", Some(detail)) => format!("persist {}", detail),
+        ("tail_logs", Some(detail)) => detail
+            .strip_prefix("lines=")
+            .map(|lines| format!("tail last {} lines", lines))
+            .unwrap_or_else(|| format!("apply {}", detail)),
+        (_, Some(detail)) => format!("apply {}", detail),
+        (_, None) => format!("run {}", action),
     }
 }