Where: import/export backup (whole-database .zip)

Package.swift

@@ -15,6 +15,7 @@ let package = Package(
     ],
     dependencies: [
         .package(url: "https://github.com/pointfreeco/swift-snapshot-testing", from: "1.19.2"),
+        .package(url: "https://github.com/weichsel/ZIPFoundation", from: "0.9.20"),
     ],
     targets: [
         .target(
@@ -23,6 +24,9 @@ let package = Package(
         ),
         .target(
             name: "WhereCore",
+            dependencies: [
+                .product(name: "ZIPFoundation", package: "ZIPFoundation"),
+            ],
             path: "Where/WhereCore/Sources",
             resources: [
                 .process("Resources"),

Where/WhereCore/Sources/Backup/BackupArchive.swift

@@ -0,0 +1,57 @@
+import Foundation
+
+/// Versioned, `Codable` manifest describing a whole-database backup of the
+/// Where feature. Serialized to `manifest.json` at the root of the backup
+/// `.zip`; evidence blob bytes live alongside it under `assets/` and are
+/// linked back to their records by `BackupAssetEntry`.
+///
+/// The three arrays mirror the three SwiftData tables exactly
+/// (`SDLocationSample` / `SDEvidence` / `SDManualDay`) via their value-type
+/// representations, so an export captures everything and an import can
+/// upsert it back row-for-row.
+public struct BackupArchive: Codable, Sendable, Hashable {
+    /// Bumped whenever the archive's on-disk shape changes in a way older
+    /// readers can't understand, so an importer can refuse a file it doesn't
+    /// know how to read instead of silently dropping data.
+    public static let currentFormatVersion = 1
+
+    public let formatVersion: Int
+    public let exportedAt: Date
+    public let samples: [LocationSample]
+    public let evidence: [Evidence]
+    public let manualDays: [DayPresence]
+    /// One entry per evidence record that has blob bytes in the archive.
+    /// Evidence without bytes simply has no entry here.
+    public let assets: [BackupAssetEntry]
+
+    public init(
+        formatVersion: Int = BackupArchive.currentFormatVersion,
+        exportedAt: Date,
+        samples: [LocationSample],
+        evidence: [Evidence],
+        manualDays: [DayPresence],
+        assets: [BackupAssetEntry],
+    ) {
+        self.formatVersion = formatVersion
+        self.exportedAt = exportedAt
+        self.samples = samples
+        self.evidence = evidence
+        self.manualDays = manualDays
+        self.assets = assets
+    }
+}
+
+/// Links one `Evidence` record to the file holding its blob bytes inside the
+/// backup archive. A named struct (rather than a bare dictionary entry or
+/// tuple) so the mapping stays self-describing in the public Codable surface.
+public struct BackupAssetEntry: Codable, Sendable, Hashable {
+    public let evidenceId: UUID
+    /// Path of the blob file relative to the archive root, e.g.
+    /// `assets/<uuid>`.
+    public let filename: String
+
+    public init(evidenceId: UUID, filename: String) {
+        self.evidenceId = evidenceId
+        self.filename = filename
+    }
+}

Where/WhereCore/Sources/Backup/BackupService.swift

@@ -0,0 +1,169 @@
+import Foundation
+import os
+import ZIPFoundation
+
+/// Serializes a whole-database backup to a `.zip` and reads one back.
+///
+/// Archive layout:
+/// ```
+/// manifest.json         // BackupArchive: samples, evidence, manual days, asset index
+/// assets/<evidence-id>  // one file per evidence blob
+/// ```
+///
+/// The service is pure file I/O over value types — it never touches
+/// SwiftData. `WhereController` owns reading the store and committing an
+/// import transaction; this type only marshals bytes to and from the zip.
+public struct BackupService: Sendable {
+    /// Decoded contents of a backup archive: the manifest plus the evidence
+    /// blob bytes, keyed by evidence id so the importer can pair them with
+    /// the matching `Evidence` metadata.
+    public struct ReadResult: Sendable {
+        public let archive: BackupArchive
+        public let blobs: [UUID: Data]
+
+        public init(archive: BackupArchive, blobs: [UUID: Data]) {
+            self.archive = archive
+            self.blobs = blobs
+        }
+    }
+
+    /// Failures specific to reading a backup file. Transport / file-system
+    /// errors surface as the underlying `Error` instead.
+    public enum BackupError: Error, LocalizedError {
+        /// The zip opened but contained no `manifest.json` at its root — it
+        /// is almost certainly not a Where backup.
+        case manifestMissing
+        /// The manifest declares a `formatVersion` newer than this build can
+        /// read (the file was produced by a later app version).
+        case unsupportedFormatVersion(Int)
+
+        public var errorDescription: String? {
+            switch self {
+                case .manifestMissing:
+                    "This file isn't a Where backup (no manifest was found)."
+                case let .unsupportedFormatVersion(version):
+                    "This backup was created by a newer version of Where (format \(version)) and can't be imported."
+            }
+        }
+    }
+
+    private static let manifestFilename = "manifest.json"
+    private static let assetsDirectory = "assets"
+    private static let logger = Logger(subsystem: "com.stuff.where", category: "BackupService")
+
+    public init() {}
+
+    private static func makeEncoder() -> JSONEncoder {
+        let encoder = JSONEncoder()
+        encoder.dateEncodingStrategy = .iso8601
+        encoder.outputFormatting = [.prettyPrinted, .sortedKeys]
+        return encoder
+    }
+
+    private static func makeDecoder() -> JSONDecoder {
+        let decoder = JSONDecoder()
+        decoder.dateDecodingStrategy = .iso8601
+        return decoder
+    }
+
+    // MARK: - Export
+
+    /// Build a backup `.zip` from the supplied data and return a URL to the
+    /// file in the temporary directory. The caller owns the file and should
+    /// delete it (or its parent directory) once it has been shared.
+    ///
+    /// `blobs` holds the evidence bytes keyed by `Evidence.id`; evidence
+    /// without an entry is exported as metadata only.
+    public func makeArchiveFile(
+        samples: [LocationSample],
+        evidence: [Evidence],
+        manualDays: [DayPresence],
+        blobs: [UUID: Data],
+        exportedAt: Date = Date(),
+        archiveName: String? = nil,
+    ) throws -> URL {
+        let fileManager = FileManager.default
+        let workRoot = fileManager.temporaryDirectory
+            .appendingPathComponent("where-backup-\(UUID().uuidString)", isDirectory: true)
+        let staging = workRoot.appendingPathComponent("contents", isDirectory: true)
+        let assetsDir = staging.appendingPathComponent(Self.assetsDirectory, isDirectory: true)
+        try fileManager.createDirectory(at: assetsDir, withIntermediateDirectories: true)
+
+        var assetEntries: [BackupAssetEntry] = []
+        for item in evidence {
+            guard let blob = blobs[item.id] else { continue }
+            let filename = "\(Self.assetsDirectory)/\(item.id.uuidString)"
+            try blob.write(to: staging.appendingPathComponent(filename))
+            assetEntries.append(BackupAssetEntry(evidenceId: item.id, filename: filename))
+        }
+
+        let archive = BackupArchive(
+            exportedAt: exportedAt,
+            samples: samples,
+            evidence: evidence,
+            manualDays: manualDays,
+            assets: assetEntries,
+        )
+        let manifestData = try Self.makeEncoder().encode(archive)
+        try manifestData.write(to: staging.appendingPathComponent(Self.manifestFilename))
+
+        let name = archiveName ?? Self.defaultArchiveName(for: exportedAt)
+        let zipURL = workRoot.appendingPathComponent(name)
+        try fileManager.zipItem(
+            at: staging,
+            to: zipURL,
+            shouldKeepParent: false,
+            compressionMethod: .deflate,
+        )
+        Self.logger.info(
+            "Wrote backup with \(samples.count) samples, \(evidence.count) evidence, \(manualDays.count) manual days",
+        )
+        return zipURL
+    }
+
+    /// A human-friendly, email-ready filename like `Where Backup 2026-06-05.zip`.
+    static func defaultArchiveName(for date: Date) -> String {
+        let formatter = DateFormatter()
+        formatter.locale = Locale(identifier: "en_US_POSIX")
+        formatter.dateFormat = "yyyy-MM-dd"
+        return "Where Backup \(formatter.string(from: date)).zip"
+    }
+
+    // MARK: - Import
+
+    /// Unzip and decode a backup file. The archive is extracted into a unique
+    /// temporary directory that is removed before returning; the decoded
+    /// manifest and blob bytes are held in memory in the result.
+    public func readArchive(at url: URL) throws -> ReadResult {
+        let fileManager = FileManager.default
+        let extractDir = fileManager.temporaryDirectory
+            .appendingPathComponent("where-import-\(UUID().uuidString)", isDirectory: true)
+        try fileManager.createDirectory(at: extractDir, withIntermediateDirectories: true)
+        defer { try? fileManager.removeItem(at: extractDir) }
+
+        try fileManager.unzipItem(at: url, to: extractDir)
+
+        let manifestURL = extractDir.appendingPathComponent(Self.manifestFilename)
+        guard fileManager.fileExists(atPath: manifestURL.path) else {
+            throw BackupError.manifestMissing
+        }
+        let manifestData = try Data(contentsOf: manifestURL)
+        let archive = try Self.makeDecoder().decode(BackupArchive.self, from: manifestData)
+        guard archive.formatVersion <= BackupArchive.currentFormatVersion else {
+            throw BackupError.unsupportedFormatVersion(archive.formatVersion)
+        }
+
+        var blobs: [UUID: Data] = [:]
+        for entry in archive.assets {
+            let assetURL = extractDir.appendingPathComponent(entry.filename)
+            guard let data = try? Data(contentsOf: assetURL) else {
+                Self.logger.fault(
+                    "Backup asset missing for evidence \(entry.evidenceId, privacy: .public); skipping blob",
+                )
+                continue
+            }
+            blobs[entry.evidenceId] = data
+        }
+        return ReadResult(archive: archive, blobs: blobs)
+    }
+}

Where/WhereCore/Sources/DayPresence.swift

@@ -4,7 +4,7 @@ import Foundation
 ///
 /// `regions` is a `Set` because we want union semantics (a day in CA + NY
 /// counts for both).
-public struct DayPresence: Hashable, Sendable {
+public struct DayPresence: Hashable, Sendable, Codable {
     /// Start-of-day in whichever calendar/timezone produced this value.
     public let date: Date
     public let regions: Set<Region>

Where/WhereCore/Sources/Persistence/SwiftDataStore.swift

@@ -257,6 +257,17 @@ public actor SwiftDataStore: WhereStore, EvidenceBlobStore {
         }
     }
 
+    public func allEvidence() async throws -> [Evidence] {
+        let context = readContext()
+        var descriptor = FetchDescriptor<SDEvidence>(sortBy: [SortDescriptor(\.capturedAt)])
+        descriptor.includePendingChanges = true
+        return try context.fetch(descriptor).compactMap { record in
+            let value = record.toValue()
+            if value == nil { Self.logFault(forCorrupt: record) }
+            return value
+        }
+    }
+
     public func evidenceBlob(for id: UUID) async throws -> Data? {
         let context = readContext()
         let descriptor = FetchDescriptor<SDEvidence>(predicate: #Predicate { $0.id == id })
@@ -315,6 +326,17 @@ public actor SwiftDataStore: WhereStore, EvidenceBlobStore {
         }
     }
 
+    public func allManualDays() async throws -> [DayPresence] {
+        let context = readContext()
+        var descriptor = FetchDescriptor<SDManualDay>(sortBy: [SortDescriptor(\.dateKey)])
+        descriptor.includePendingChanges = true
+        return try context.fetch(descriptor).compactMap { record in
+            let value = record.toValue()
+            if value == nil { Self.logFault(forCorrupt: record) }
+            return value
+        }
+    }
+
     public func clear(in interval: DateInterval) async throws {
         let context = mutationContext()
         let start = interval.start
@@ -357,6 +379,19 @@ public actor SwiftDataStore: WhereStore, EvidenceBlobStore {
         }
     }
 
+    public func clearAll() async throws {
+        let context = mutationContext()
+        for sample in try context.fetch(FetchDescriptor<SDLocationSample>()) {
+            context.delete(sample)
+        }
+        for evidence in try context.fetch(FetchDescriptor<SDEvidence>()) {
+            context.delete(evidence)
+        }
+        for manual in try context.fetch(FetchDescriptor<SDManualDay>()) {
+            context.delete(manual)
+        }
+    }
+
     private static func logFault<Record>(forCorrupt _: Record) {
         logger.fault(
             "Dropped corrupt SwiftData record of type \(String(describing: Record.self), privacy: .public)",

Where/WhereCore/Sources/Persistence/WhereStore.swift

@@ -32,15 +32,25 @@ public protocol WhereStore: Sendable {
 
     func write(evidence: Evidence, blob: Data?) async throws
     func evidence(in interval: DateInterval) async throws -> [Evidence]
+    /// Every evidence record in the store, regardless of `capturedAt`. Used
+    /// by the whole-database backup export.
+    func allEvidence() async throws -> [Evidence]
     func evidenceBlob(for id: UUID) async throws -> Data?
 
     /// Set (or replace) the manual presence record for a given calendar day.
     /// Implementations should treat `day.date` as already normalized to the
     /// start-of-day key (callers via `WhereController` do this for them).
     func setManualDay(_ day: DayPresence) async throws
     func manualDays(in interval: DateInterval) async throws -> [DayPresence]
+    /// Every manual-day record in the store, regardless of `dateKey`. Used
+    /// by the whole-database backup export.
+    func allManualDays() async throws -> [DayPresence]
 
     /// Erase all samples / evidence / manual entries whose timestamp lies in
     /// the given interval. Used by `WhereController.clearYear`.
     func clear(in interval: DateInterval) async throws
+
+    /// Erase every sample / evidence / manual entry in the store. Used by the
+    /// "replace" backup-import strategy to mirror the imported file exactly.
+    func clearAll() async throws
 }