fix #5 camera video preview with settling and diagnostics

- Wait until the picker movie's file size stops changing before
  staging it, so a movie whose final bytes are still being flushed is
  never copied truncated (which produced drafts without a thumbnail
  and unplayable previews).
- Log the whole camera video path (pickup size, staging result,
  analyze outcome, thumbnail decode) under the video-preview os_log
  category for fast on-device diagnosis.
- Cover the video analysis pipeline with a simulator test that
  generates an HEVC QuickTime movie and asserts duration plus JPEG
  thumbnail, and guard the diagnostics in Scripts/verify.sh.

Sources/Shared/Services/MediaPreviewProcessor.swift

@@ -1,6 +1,7 @@
 import AVFoundation
 import Foundation
 import ImageIO
+import os
 import UniformTypeIdentifiers
 
 actor MediaPreviewProcessor {
@@ -44,6 +45,12 @@ actor MediaPreviewProcessor {
         }
 
         let waveform = kind == .voice ? voiceWaveform(for: url) : nil
+        if kind == .video {
+            let logger = Logger(subsystem: "Luma", category: "video-preview")
+            logger.info(
+                "analyze video: \(url.lastPathComponent) duration=\(String(describing: duration)) thumbnailBytes=\(thumbnailData?.count ?? 0)"
+            )
+        }
         return Analysis(
             duration: duration,
             thumbnailData: thumbnailData,
@@ -94,6 +101,8 @@ actor MediaPreviewProcessor {
                     return data
                 }
             } catch {
+                Logger(subsystem: "Luma", category: "video-preview")
+                    .error("image generator failed at \(second)s: \(error.localizedDescription)")
                 continue
             }
         }

Sources/Shared/UI/AttachmentPreviewView.swift

@@ -1,4 +1,5 @@
 import Foundation
+import os
 import SwiftUI
 
 #if os(iOS)
@@ -239,7 +240,13 @@ struct AttachmentPreviewView: View {
         thumbnailImages = thumbnailImages.filter { retainedIDs.contains($0.key) }
         for draft in drafts where thumbnailImages[draft.id] == nil {
             guard let data = draft.thumbnailData,
-                  let image = DraftThumbnailImage(data: data) else { continue }
+                  let image = DraftThumbnailImage(data: data) else {
+                if draft.kind == .video {
+                    Logger(subsystem: "Luma", category: "video-preview")
+                        .warning("video draft has no decodable thumbnail: \(draft.filename) thumbnailBytes=\(draft.thumbnailData?.count ?? 0)")
+                }
+                continue
+            }
             thumbnailImages[draft.id] = image
             await Task.yield()
         }

Sources/Shared/UI/ChatView.swift

@@ -1,6 +1,7 @@
 import CoreTransferable
 import Foundation
 import ImageIO
+import os
 import PhotosUI
 import SwiftData
 import SwiftUI
@@ -1263,12 +1264,44 @@ struct ChatView: View {
             photoCameraIsPreparingResult = false
             releaseArchiveSyncAfterCapture()
         }
+        let logger = Logger(subsystem: "Luma", category: "video-preview")
+        await waitForCameraFileSettling(at: media.url, logger: logger)
         let staged = await stageImportedFiles([media.url], preferredKind: media.kind)
-        if !staged, model.errorMessage == nil {
-            model.errorMessage = "Камера вернула файл, который не удалось подготовить к отправке."
+        if staged {
+            if let draft = attachmentDrafts.last {
+                logger.info(
+                    "camera draft staged: kind=\(draft.kind.rawValue) mime=\(draft.mimeType) size=\(draft.byteCount) duration=\(String(describing: draft.duration)) thumbnailBytes=\(draft.thumbnailData?.count ?? 0)"
+                )
+            }
+        } else {
+            logger.error("camera staging produced no drafts")
+            if model.errorMessage == nil {
+                model.errorMessage = "Камера вернула файл, который не удалось подготовить к отправке."
+            }
         }
     }
 
+    /// The picker can hand over a movie whose final bytes are still being
+    /// flushed. Wait until the file size stops changing so staging never
+    /// copies a truncated file.
+    private func waitForCameraFileSettling(at url: URL, logger: Logger) async {
+        guard let initial = try? url.resourceValues(forKeys: [.fileSizeKey]).fileSize else {
+            return
+        }
+        var previous = initial
+        for _ in 0..<10 {
+            try? await Task.sleep(nanoseconds: 250_000_000)
+            guard let current = try? url.resourceValues(forKeys: [.fileSizeKey]).fileSize else {
+                return
+            }
+            if current == previous {
+                return
+            }
+            previous = current
+        }
+        logger.warning("camera file size kept changing; staging anyway")
+    }
+
     private func presentCamera() {
         #if os(iOS)
             guard SystemPhotoCameraView.isAvailable else {

Sources/Shared/UI/SystemPhotoCameraView.swift

@@ -1,4 +1,5 @@
 import Foundation
+import os
 
 struct CapturedCameraMedia: Sendable {
     let url: URL
@@ -121,7 +122,10 @@ struct SystemPhotoCameraView: UIViewControllerRepresentable {
         /// races that cleanup and fails with an unreadable source. The move
         /// is a same-volume rename and does not block the main thread.
         private func prepareMovie(from sourceURL: URL) {
+            let logger = Logger(subsystem: "Luma", category: "video-preview")
             do {
+                let sourceSize = (try? sourceURL.resourceValues(forKeys: [.fileSizeKey]).fileSize) ?? -1
+                logger.info("picker movie ready: source=\(sourceURL.lastPathComponent) size=\(sourceSize)")
                 let fileExtension = sourceURL.pathExtension.isEmpty
                     ? "mov"
                     : sourceURL.pathExtension
@@ -130,13 +134,15 @@ struct SystemPhotoCameraView: UIViewControllerRepresentable {
                 let values = try destination.resourceValues(
                     forKeys: [.fileSizeKey, .isRegularFileKey]
                 )
-                guard values.isRegularFile == true,
-                      (values.fileSize ?? 0) > 0 else {
+                let movedSize = values.fileSize ?? 0
+                logger.info("picker movie moved: size=\(movedSize) regular=\(values.isRegularFile == true)")
+                guard values.isRegularFile == true, movedSize > 0 else {
                     try? FileManager.default.removeItem(at: destination)
                     throw SystemCameraError.emptyMovie
                 }
                 onMedia(.success(CapturedCameraMedia(url: destination, kind: .video)))
             } catch {
+                logger.error("picker movie preparation failed: \(error.localizedDescription)")
                 onMedia(.failure(error))
             }
         }