Omit hash scheme from image.id. (#1658)

- Closes #1657.
- Also reduces `trimDigest()` output to 12 characters and gets rid of
the trailing ellipsis.

Sources/ContainerResource/Image/ImageResource.swift

@@ -69,8 +69,14 @@ public struct ImageResource: ManagedResource {
 
     // MARK: ManagedResource
 
-    /// The unique identifier for this image. Identical to the image's index digest.
-    public var id: String { configuration.descriptor.digest }
+    /// The scheme-specific value of `configuration.descriptor.digest` (the hex portion
+    /// after the algorithm prefix). The fully-qualified digest — needed for content-store
+    /// lookups and XPC transport — is always recoverable as `configuration.descriptor.digest`.
+    public var id: String {
+        let digest = configuration.descriptor.digest
+        guard let colonIndex = digest.firstIndex(of: ":") else { return digest }
+        return String(digest[digest.index(after: colonIndex)...])
+    }
 
     /// The user-facing reference (`name:tag`) for this image.
     public var name: String { configuration.name }

Sources/Services/ContainerAPIService/Client/Utility.swift

@@ -44,12 +44,11 @@ public struct Utility {
     }
 
     public static func trimDigest(digest: String) -> String {
-        var digest = digest
-        digest.trimPrefix("sha256:")
-        if digest.count > 24 {
-            digest = String(digest.prefix(24)) + "..."
+        var hex = digest
+        if let colonIndex = digest.firstIndex(of: ":") {
+            hex = String(digest[digest.index(after: colonIndex)...])
         }
-        return digest
+        return String(hex.prefix(12))
     }
 
     public static func validEntityName(_ name: String) throws {

Tests/ContainerAPIClientTests/UtilityTests.swift

@@ -90,6 +90,29 @@ struct UtilityTests {
         }
     }
 
+    @Test("Trim fully-qualified digest strips scheme and truncates to 12 chars")
+    func testTrimDigestFullyQualified() {
+        let hex = "0be69a25c33692845efb1e93f4254f28505a330896376bf8"
+        #expect(Utility.trimDigest(digest: "sha256:\(hex)") == String(hex.prefix(12)))
+    }
+
+    @Test("Trim digest with unknown scheme strips scheme prefix")
+    func testTrimDigestUnknownScheme() {
+        let hex = "abcdef123456789012345678"
+        #expect(Utility.trimDigest(digest: "blake3:\(hex)") == String(hex.prefix(12)))
+    }
+
+    @Test("Trim digest with no scheme truncates directly")
+    func testTrimDigestNoScheme() {
+        let hex = "abcdef1234567890"
+        #expect(Utility.trimDigest(digest: hex) == String(hex.prefix(12)))
+    }
+
+    @Test("Trim digest shorter than 12 chars returns value unchanged")
+    func testTrimDigestShort() {
+        #expect(Utility.trimDigest(digest: "sha256:abc") == "abc")
+    }
+
     @Test
     func testPublishPortParser() throws {
         let ports = try Parser.publishPorts([

docs/tutorials/start-here.md

@@ -163,8 +163,8 @@ After the build completes, list the images. You should see both the base image a
 <pre>
 % container image list
 NAME      TAG     DIGEST
-python    alpine  b4d299311845147e7e47c970...
-web-test  latest  25b99501f174803e21c58f9c...
+python    alpine  b4d299311845
+web-test  latest  25b99501f174
 %
 </pre>