carry of #27877: send iOS agent images

cmux-next-ios/CmuxMobileKit/Sources/CmuxMobileChief/ChiefCompose.swift

@@ -195,17 +195,26 @@ public final class ChiefComposer {
         session.send(routed)
     }
 
-    /// New Message's images as an agent prompt's attachments, bytes and order kept.
+    /// New Message's images as agent prompt attachments, normalized to formats agents accept.
     static func attachments(_ images: [ConversationComposeImage]) -> [AgentAttachment] {
         images.enumerated().map { index, image in
-            let ext = switch image.mimeType.lowercased() {
-            case "image/png": "png"
-            case "image/gif": "gif"
-            case "image/webp": "webp"
-            case "image/heic": "heic"
-            default: "jpg"
+            let source = AgentAttachment(kind: .image, name: "Image \(index + 1)", data: image.data)
+            let data: Data
+            let kind: AgentAttachment.Kind
+            let ext: String
+            switch source.imageMIMEType {
+            case "image/png": data = image.data; kind = .image; ext = "png"
+            case "image/jpeg": data = image.data; kind = .image; ext = "jpg"
+            case "image/gif": data = image.data; kind = .image; ext = "gif"
+            case "image/webp": data = image.data; kind = .image; ext = "webp"
+            default:
+                if let jpeg = UIImage(data: image.data)?.jpegData(compressionQuality: 0.85) {
+                    data = jpeg; kind = .image; ext = "jpg"
+                } else {
+                    data = image.data; kind = .file; ext = "bin"
+                }
             }
-            return AgentAttachment(kind: .image, name: "Image \(index + 1).\(ext)", data: image.data)
+            return AgentAttachment(kind: kind, name: "Image \(index + 1).\(ext)", data: data)
         }
     }
 

cmux-next-ios/CmuxMobileKit/Tests/CmuxMobileChiefTests/ChiefTests.swift

@@ -662,6 +662,8 @@ private let tinyPNG = Data(base64Encoded: "iVBORw0KGgoAAAANSUhEUgAAAAQAAAADCAIAA
 }
 
 #if os(iOS)
+import UIKit
+
 @Suite @MainActor struct ChiefDirectoryTests {
     func directory() -> ChiefDirectory {
         let chief = ChiefDirectory.recipients(store: AppStore(teams: [], activeTeamID: "", workspaces: [], feed: []), identity: .standard, place: .mac)
@@ -762,6 +764,50 @@ private let tinyPNG = Data(base64Encoded: "iVBORw0KGgoAAAANSUhEUgAAAAQAAAADCAIAA
         #expect(Set(prompt.attachments.map(\.id)).count == 2)
     }
 
+    @Test func encodedImageBytesOverrideDeclaredMimeType() throws {
+        let renderer = UIGraphicsImageRenderer(size: CGSize(width: 2, height: 2))
+        let validPNG = renderer.pngData { context in
+            UIColor.red.setFill()
+            context.fill(CGRect(x: 0, y: 0, width: 2, height: 2))
+        }
+        let image = ConversationComposeImage(data: validPNG, width: 2, height: 2, mimeType: "image/heic")
+        let attachment = try #require(ChiefComposer.attachments([image]).first)
+        #expect(attachment.name.hasSuffix(".png"))
+        #expect(attachment.imageMIMEType == "image/png")
+        #expect(attachment.data == validPNG)
+    }
+
+    @Test func imageBytesWinOverTheDeclaredMimeType() throws {
+        let image = ConversationComposeImage(data: Self.png, width: 1, height: 1, mimeType: "image/heic")
+        let attachment = try #require(ChiefComposer.attachments([image]).first)
+        #expect(attachment.kind == .image)
+        #expect(attachment.name.hasSuffix(".png"))
+        #expect(attachment.imageMIMEType == "image/png")
+    }
+
+    @Test func unsupportedDecodedImageIsConvertedToJpeg() throws {
+        // A complete 1x1, 24-bit BMP (red pixel, padded four-byte row).
+        let bmp = try #require(Data(base64Encoded: "Qk06AAAAAAAAADYAAAAoAAAAAQAAAAEAAAABABgAAAAAAAQAAAAAAAAAAAAAAAAAAAAAAAAAAAD/AA=="))
+        try #require(UIImage(data: bmp) != nil)
+        #expect(AgentAttachment(kind: .image, name: "source", data: bmp).imageMIMEType == nil)
+        let attachment = try #require(ChiefComposer.attachments([
+            ConversationComposeImage(data: bmp, width: 1, height: 1, mimeType: "image/jpeg")
+        ]).first)
+        #expect(attachment.kind == .image)
+        #expect(attachment.name.hasSuffix(".jpg"))
+        #expect(attachment.imageMIMEType == "image/jpeg")
+        #expect(attachment.data != bmp)
+        let jpeg = try #require(attachment.data)
+        #expect(UIImage(data: jpeg) != nil)
+    }
+
+    @Test func undecodableImageIsSentAsAFile() throws {
+        let image = ConversationComposeImage(data: Data([0x01, 0x02, 0x03]), width: 1, height: 1, mimeType: "image/png")
+        let attachment = try #require(ChiefComposer.attachments([image]).first)
+        #expect(attachment.kind == .file)
+        #expect(attachment.imageMIMEType == nil)
+    }
+
     @Test func anImageOnlyMessageStillSends() throws {
         let prompts = route(ConversationComposeMessage(text: "", images: [
             ConversationComposeImage(data: Self.png, width: 1, height: 1, mimeType: "image/png"),