feat(rewind): add deviceName to screenshots for multi-device disambiguation

desktop/Desktop/Sources/Chat/ChatPrompts.swift

@@ -947,6 +947,7 @@ struct ChatPrompts {
             "ocrText": "Full OCR-extracted text from the screen",
             "focusStatus": "Whether user was focused or distracted (focused/distracted)",
             "skippedForBattery": "OCR was skipped on battery; text may be missing",
+            "deviceName": "Computer/device name that captured this screenshot (for multi-device queries)",
         ],
         "action_items": [
             "description": "The task text shown to the user",

desktop/Desktop/Sources/Rewind/Core/RewindDatabase.swift

@@ -2156,6 +2156,14 @@ actor RewindDatabase {
             }
         }
 
+        migrator.registerMigration("addDeviceName") { db in
+            try db.alter(table: "screenshots") { t in
+                t.add(column: "deviceName", .text)
+            }
+        }
+            }
+        }
+
         try migrator.migrate(queue)
     }
 

desktop/Desktop/Sources/Rewind/Core/RewindModels.swift

@@ -47,6 +47,9 @@ struct Screenshot: Codable, FetchableRecord, PersistableRecord, Identifiable, Eq
     /// Whether OCR was skipped because the Mac was on battery (needs backfill when AC reconnects)
     var skippedForBattery: Bool
 
+    /// Computer/device name that captured this screenshot (for multi-device disambiguation)
+    var deviceName: String?
+
     static let databaseTableName = "screenshots"
 
     // MARK: - Storage Type
@@ -72,7 +75,8 @@ struct Screenshot: Codable, FetchableRecord, PersistableRecord, Identifiable, Eq
         focusStatus: String? = nil,
         extractedTasksJson: String? = nil,
         adviceJson: String? = nil,
-        skippedForBattery: Bool = false
+        skippedForBattery: Bool = false,
+        deviceName: String? = nil
     ) {
         self.id = id
         self.timestamp = timestamp
@@ -88,6 +92,7 @@ struct Screenshot: Codable, FetchableRecord, PersistableRecord, Identifiable, Eq
         self.extractedTasksJson = extractedTasksJson
         self.adviceJson = adviceJson
         self.skippedForBattery = skippedForBattery
+        self.deviceName = deviceName
     }
 
     // MARK: - Persistence Callbacks

desktop/Desktop/Sources/Rewind/Services/RewindIndexer.swift

@@ -6,6 +6,9 @@ import Foundation
 actor RewindIndexer {
     static let shared = RewindIndexer()
 
+    /// Capture-time computer name for new screenshots created by this app session.
+    private let currentComputerName = Host.current().localizedName
+
     private var isInitialized = false
     private var isInitializing = false
 
@@ -212,7 +215,8 @@ actor RewindIndexer {
                 ocrText: ocrText,
                 ocrDataJson: ocrDataJson,
                 isIndexed: isIndexed,
-                skippedForBattery: skippedForBattery
+                skippedForBattery: skippedForBattery,
+                deviceName: currentComputerName
             )
 
             let inserted = try await RewindDatabase.shared.insertScreenshot(screenshot)
@@ -293,7 +297,8 @@ actor RewindIndexer {
                 ocrText: ocrText,
                 ocrDataJson: ocrDataJson,
                 isIndexed: isIndexed,
-                skippedForBattery: skippedForBattery
+                skippedForBattery: skippedForBattery,
+                deviceName: currentComputerName
             )
 
             let inserted = try await RewindDatabase.shared.insertScreenshot(screenshot)
@@ -398,7 +403,8 @@ actor RewindIndexer {
                 focusStatus: focusStatus,
                 extractedTasksJson: tasksJson,
                 adviceJson: adviceJson,
-                skippedForBattery: skippedForBattery
+                skippedForBattery: skippedForBattery,
+                deviceName: currentComputerName
             )
 
             let inserted = try await RewindDatabase.shared.insertScreenshot(screenshot)
@@ -613,7 +619,9 @@ actor RewindIndexer {
                         frameOffset: frame.frameOffset,
                         ocrText: nil,
                         ocrDataJson: nil,
-                        isIndexed: false  // Will need re-OCR
+                        isIndexed: false,  // Will need re-OCR
+                        // Rebuild provenance is unknown for historical frames recovered from disk.
+                        deviceName: nil
                     )
 
                     try await RewindDatabase.shared.insertScreenshot(screenshot)

desktop/Desktop/Sources/ScreenActivitySyncService.swift

@@ -80,7 +80,7 @@ actor ScreenActivitySyncService {
             // Query screenshots that have embeddings and are newer than our cursor
             let rows: [[String: Any]] = try await dbPool.read { [lastSyncedId, batchSize] db in
                 let sql = """
-                    SELECT id, timestamp, appName, windowTitle, ocrText, embedding
+                    SELECT id, timestamp, appName, windowTitle, ocrText, embedding, deviceName
                     FROM screenshots
                     WHERE id > ? AND embedding IS NOT NULL
                     ORDER BY id ASC
@@ -103,6 +103,9 @@ actor ScreenActivitySyncService {
                     dict["appName"] = (row["appName"] as? String) ?? ""
                     dict["windowTitle"] = (row["windowTitle"] as? String) ?? ""
                     dict["ocrText"] = (row["ocrText"] as? String) ?? ""
+                    if let deviceName = row["deviceName"] as? String {
+                        dict["deviceName"] = deviceName
+                    }
 
                     // Convert embedding BLOB to [Double] array
                     let blobValue = row["embedding"] as DatabaseValue