Add existing sync target

src/cli.rs

@@ -45,6 +45,9 @@ pub enum SyncTarget {
     Studio,
     /// Write assets to the .asphalt-debug folder.
     Debug,
+    /// Generate code from existing lockfile entries only.
+    /// Fails if any asset is not already in the lockfile.
+    Existing,
 }
 
 impl SyncTarget {

src/sync/collect.rs

@@ -161,6 +161,7 @@ impl Progress {
                 SyncTarget::Cloud { dry_run: true } => "checked",
                 SyncTarget::Cloud { dry_run: false } => "uploaded",
                 SyncTarget::Studio | SyncTarget::Debug => "written",
+                SyncTarget::Existing => "resolved",
             };
             parts.push(format!("{} {}", self.new, target_msg));
         }

src/sync/mod.rs

@@ -103,6 +103,7 @@ pub async fn sync(args: SyncArgs, mp: MultiProgress) -> anyhow::Result<()> {
                 SyncTarget::Studio => {
                     Some(TargetBackend::Studio(backend::Studio::new(params).await?))
                 }
+                SyncTarget::Existing => None,
             }
         },
     };

src/sync/walk.rs

@@ -6,7 +6,7 @@ use crate::{
     lockfile::Lockfile,
     sync::TargetBackend,
 };
-use anyhow::Context;
+use anyhow::{Context, bail};
 use fs_err::tokio as fs;
 use log::{debug, warn};
 use relative_path::PathExt;
@@ -124,6 +124,13 @@ async fn process_entry(
         .existing_lockfile
         .get(&state.input_name, &asset.hash);
 
+    if matches!(state.params.target, SyncTarget::Existing) && lockfile_entry.is_none() {
+        bail!(
+            "Asset '{}' is not in the lockfile. Upload it first with 'asphalt sync'.",
+            rel_path
+        );
+    }
+
     {
         let mut seen_hashes = state.seen_hashes.lock().await;