feat: add opt-in crash reporting with MetricKit (#472)

Pine/ContentView+Helpers.swift

@@ -480,6 +480,22 @@ extension ContentView {
     }
 }
 
+// MARK: - Crash Reporting Opt-In
+
+extension ContentView {
+    /// Shows the crash reporting opt-in dialog on first launch.
+    /// Sets `hasShownPrompt` immediately to prevent duplicate dialogs across multiple windows.
+    func showCrashReportingOptInIfNeeded() {
+        guard CrashReportingSettings.needsPrompt else { return }
+        // Mark as shown BEFORE the async delay to prevent race with other windows
+        CrashReportingSettings.hasShownPrompt = true
+        // Slight delay to avoid showing during initial window setup
+        DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) {
+            showCrashReportingOptIn = true
+        }
+    }
+}
+
 // MARK: - Line / offset helpers
 
 extension ContentView {

Pine/ContentView.swift

@@ -36,6 +36,7 @@ struct ContentView: View {
     @State var isQuickOpenPresented = false
     @State var isSymbolNavigatorPresented = false
     @State var showGoToLine = false
+    @State var showCrashReportingOptIn = false
     @AppStorage("minimapVisible") var isMinimapVisible = true
     @AppStorage(BlameConstants.storageKey) var isBlameVisible = true
     @AppStorage("wordWrapEnabled") var isWordWrapEnabled = true
@@ -114,6 +115,7 @@ struct ContentView: View {
             syncSidebarSelection()
             applySearchQueryFromEnvironment()
             refreshBlame()
+            showCrashReportingOptInIfNeeded()
         }
         .sheet(isPresented: $showRecoveryDialog) {
             RecoveryDialogView(
@@ -223,6 +225,13 @@ struct ContentView: View {
             tabManager.pendingGoToLine = nil
             goToLineOffset = GoToRequest(offset: Self.cursorOffset(forLine: line, in: tab.content))
         }
+        .sheet(isPresented: $showCrashReportingOptIn) {
+            CrashReportingOptInView(isPresented: $showCrashReportingOptIn) { enabled in
+                if enabled {
+                    CrashReportingManager.shared.startIfEnabled()
+                }
+            }
+        }
     }
 
     /// Branch subtitle as a plain String to avoid generating a localization key.

Pine/CrashReport.swift

@@ -0,0 +1,104 @@
+//
+//  CrashReport.swift
+//  Pine
+//
+//  Model for crash diagnostic data collected via MetricKit.
+//
+
+import Foundation
+
+/// A structured crash report collected from MetricKit diagnostics.
+struct CrashReport: Codable, Equatable, Sendable {
+    /// Unique identifier for deduplication.
+    let id: UUID
+
+    /// Timestamp when the crash occurred.
+    let timestamp: Date
+
+    /// App version at the time of crash (CFBundleShortVersionString).
+    let appVersion: String
+
+    /// Build number at the time of crash (CFBundleVersion).
+    let buildNumber: String
+
+    /// macOS version string (e.g. "26.0").
+    let osVersion: String
+
+    /// Signal that caused the crash (e.g. SIGSEGV, SIGABRT).
+    let signal: String?
+
+    /// Exception type if available.
+    let exceptionType: String?
+
+    /// Termination reason if available.
+    let terminationReason: String?
+
+    /// Call stack frames as human-readable strings.
+    let callStackFrames: [String]
+
+    /// Number of open editor tabs at crash time (privacy-safe metric).
+    let openTabCount: Int?
+
+    /// Creates a CrashReport with current app/OS metadata.
+    init(
+        id: UUID = UUID(),
+        timestamp: Date = Date(),
+        signal: String? = nil,
+        exceptionType: String? = nil,
+        terminationReason: String? = nil,
+        callStackFrames: [String] = [],
+        openTabCount: Int? = nil
+    ) {
+        self.id = id
+        self.timestamp = timestamp
+        self.appVersion = Bundle.main.object(forInfoDictionaryKey: "CFBundleShortVersionString") as? String ?? "unknown"
+        self.buildNumber = Bundle.main.object(forInfoDictionaryKey: "CFBundleVersion") as? String ?? "unknown"
+        self.osVersion = ProcessInfo.processInfo.operatingSystemVersionString
+        self.signal = signal
+        self.exceptionType = exceptionType
+        self.terminationReason = terminationReason
+        self.callStackFrames = callStackFrames
+        self.openTabCount = openTabCount
+    }
+
+    /// Internal initializer for testing with explicit app/OS values.
+    init(
+        id: UUID,
+        timestamp: Date,
+        appVersion: String,
+        buildNumber: String,
+        osVersion: String,
+        signal: String?,
+        exceptionType: String?,
+        terminationReason: String?,
+        callStackFrames: [String],
+        openTabCount: Int?
+    ) {
+        self.id = id
+        self.timestamp = timestamp
+        self.appVersion = appVersion
+        self.buildNumber = buildNumber
+        self.osVersion = osVersion
+        self.signal = signal
+        self.exceptionType = exceptionType
+        self.terminationReason = terminationReason
+        self.callStackFrames = callStackFrames
+        self.openTabCount = openTabCount
+    }
+}
+
+// MARK: - Call Stack Parsing
+
+extension CrashReport {
+    /// Parses a raw call stack string into individual frame strings.
+    /// Handles both MetricKit JSON format and standard crash log format.
+    ///
+    /// Each frame typically looks like:
+    /// `0   Pine                        0x00000001000a1234 someFunction + 42`
+    static func parseCallStack(_ rawCallStack: String) -> [String] {
+        let lines = rawCallStack.components(separatedBy: .newlines)
+        return lines
+            .map { $0.trimmingCharacters(in: .whitespaces) }
+            .filter { !$0.isEmpty }
+    }
+}

Pine/CrashReportStore.swift

@@ -0,0 +1,187 @@
+//
+//  CrashReportStore.swift
+//  Pine
+//
+//  Persists crash reports to disk for display on next launch.
+//
+
+import AppKit
+import Foundation
+import os
+
+/// Persists crash reports as JSON files in the Application Support directory.
+/// Reports are stored individually for atomic read/write and easy cleanup.
+///
+/// Thread-safe: all file I/O is serialized on an internal serial queue.
+/// Safe to call from MetricKit callbacks (arbitrary threads) and from the main thread.
+final class CrashReportStore {
+    /// Shared singleton instance.
+    static let shared = CrashReportStore()
+
+    /// Directory where crash reports are stored.
+    let storageDirectory: URL
+
+    private let logger = Logger(subsystem: "com.pine.editor", category: "CrashReportStore")
+
+    /// Serial queue that serializes all disk I/O for thread safety.
+    private let queue = DispatchQueue(label: "com.pine.crash-report-store")
+
+    /// Maximum number of reports to keep on disk.
+    static let maxReports = 50
+
+    /// File extension for crash report files.
+    static let fileExtension = "crashreport"
+
+    init(storageDirectory: URL? = nil) {
+        if let dir = storageDirectory {
+            self.storageDirectory = dir
+        } else if let appSupport = FileManager.default.urls(
+            for: .applicationSupportDirectory, in: .userDomainMask
+        ).first {
+            self.storageDirectory = appSupport.appendingPathComponent("Pine/CrashReports")
+        } else {
+            self.storageDirectory = URL(fileURLWithPath: NSTemporaryDirectory())
+                .appendingPathComponent("Pine/CrashReports")
+        }
+        try? FileManager.default.createDirectory(at: self.storageDirectory, withIntermediateDirectories: true)
+    }
+
+    /// Saves a crash report to disk.
+    func save(_ report: CrashReport) {
+        queue.sync {
+            _save(report)
+        }
+    }
+
+    /// Loads all stored crash reports, sorted by timestamp (newest first).
+    func loadAll() -> [CrashReport] {
+        queue.sync {
+            _loadAll()
+        }
+    }
+
+    /// Removes a specific crash report by ID.
+    func remove(id: UUID) {
+        queue.sync {
+            _remove(id: id)
+        }
+    }
+
+    /// Removes all stored crash reports.
+    func removeAll() {
+        queue.sync {
+            _removeAll()
+        }
+    }
+
+    /// Returns the number of stored reports (directory listing only, no JSON decoding).
+    var count: Int {
+        queue.sync {
+            _count()
+        }
+    }
+
+    /// Whether the store has no reports (directory listing only, no JSON decoding).
+    var isEmpty: Bool {
+        queue.sync {
+            _count() == 0
+        }
+    }
+
+    /// Reveals the crash reports directory in Finder.
+    func revealInFinder() {
+        NSWorkspace.shared.selectFile(nil, inFileViewerRootedAtPath: storageDirectory.path)
+    }
+
+    /// Copies all crash reports as JSON to the clipboard.
+    /// Returns the number of reports copied.
+    @discardableResult
+    func copyAllToClipboard() -> Int {
+        let reports = loadAll()
+        guard !reports.isEmpty else { return 0 }
+
+        let encoder = JSONEncoder()
+        encoder.outputFormatting = [.prettyPrinted, .sortedKeys]
+        encoder.dateEncodingStrategy = .iso8601
+
+        guard let data = try? encoder.encode(reports),
+              let jsonString = String(data: data, encoding: .utf8) else {
+            return 0
+        }
+
+        let pasteboard = NSPasteboard.general
+        pasteboard.clearContents()
+        pasteboard.setString(jsonString, forType: .string)
+        return reports.count
+    }
+
+    // MARK: - Private (must be called on self.queue)
+
+    private func _save(_ report: CrashReport) {
+        let fileName = "\(report.id.uuidString).\(Self.fileExtension)"
+        let fileURL = storageDirectory.appendingPathComponent(fileName)
+
+        do {
+            let data = try JSONEncoder().encode(report)
+            try data.write(to: fileURL, options: .atomic)
+            _pruneOldReports()
+        } catch {
+            logger.error("Failed to save crash report: \(error.localizedDescription)")
+        }
+    }
+
+    private func _loadAll() -> [CrashReport] {
+        let fm = FileManager.default
+        guard let files = try? fm.contentsOfDirectory(at: storageDirectory, includingPropertiesForKeys: nil) else {
+            return []
+        }
+
+        let reports: [CrashReport] = files
+            .filter { $0.pathExtension == Self.fileExtension }
+            .compactMap { url in
+                guard let data = try? Data(contentsOf: url),
+                      let report = try? JSONDecoder().decode(CrashReport.self, from: data) else {
+                    return nil
+                }
+                return report
+            }
+            .sorted { $0.timestamp > $1.timestamp }
+
+        return reports
+    }
+
+    private func _remove(id: UUID) {
+        let fileName = "\(id.uuidString).\(Self.fileExtension)"
+        let fileURL = storageDirectory.appendingPathComponent(fileName)
+        try? FileManager.default.removeItem(at: fileURL)
+    }
+
+    private func _removeAll() {
+        let fm = FileManager.default
+        guard let files = try? fm.contentsOfDirectory(at: storageDirectory, includingPropertiesForKeys: nil) else {
+            return
+        }
+        for file in files where file.pathExtension == Self.fileExtension {
+            try? fm.removeItem(at: file)
+        }
+    }
+
+    private func _count() -> Int {
+        let fm = FileManager.default
+        guard let files = try? fm.contentsOfDirectory(at: storageDirectory, includingPropertiesForKeys: nil) else {
+            return 0
+        }
+        return files.filter { $0.pathExtension == Self.fileExtension }.count
+    }
+
+    /// Prunes old reports if count exceeds the maximum.
+    private func _pruneOldReports() {
+        let reports = _loadAll()
+        guard reports.count > Self.maxReports else { return }
+
+        let toRemove = reports.suffix(from: Self.maxReports)
+        for report in toRemove {
+            _remove(id: report.id)
+        }
+    }
+}