podstorage: Skip copy if image already in bootc storage; mark digest dead_code

When an image was built via 'bootc image cmd build' it goes directly into
bootc's containers-storage. pull_from_containers_storage should detect this
and skip the copy step rather than trying to copy from the default (host)
storage where the image does not exist.

Also marks the digest field on ImageListEntry as dead_code since we now
match by config digest (image ID) rather than manifest digest.

Assisted-by: OpenCode (claude-sonnet-4-6@default)
Signed-off-by: Colin Walters <walters@verbum.org>

Author: cgwalters

crates/lib/src/podman.rs

@@ -19,10 +19,10 @@ pub(crate) struct Inspect {
 pub(crate) struct ImageListEntry {
     pub(crate) id: String,
     pub(crate) names: Option<Vec<String>>,
-    /// Manifest digest for this image (e.g. `sha256:abc...`).
-    ///
-    /// Populated by `podman image list --format=json` in modern podman versions.
-    /// Used to cross-reference against composefs bootc tags.
+    /// Manifest digest as reported by podman (may differ from the composefs
+    /// OCI manifest digest when layers are recompressed during copy).
+    /// Kept for diagnostic purposes; use `id` (config sha256) for matching.
+    #[allow(dead_code)]
     pub(crate) digest: Option<String>,
 }
 

crates/lib/src/podstorage.rs

@@ -451,6 +451,13 @@ impl CStorage {
     /// image stores when resolving a push source.  Otherwise falls back to the
     /// default `/var/lib/containers/storage`.
     pub(crate) async fn pull_from_containers_storage(&self, image: &str) -> Result<()> {
+        // If the image is already in bootc's own containers-storage (e.g. built
+        // via `bootc image cmd build`), no copy is needed.
+        if self.exists(image).await.unwrap_or(false) {
+            tracing::debug!("Image {image} already in bootc storage; skipping copy");
+            return Ok(());
+        }
+
         let ais = std::env::var("STORAGE_OPTS")
             .ok()
             .and_then(|v| {