diff --git a/platforms/macos/Sources/AppState+AutoKill.swift b/platforms/macos/Sources/AppState+AutoKill.swift
new file mode 100644
index 0000000..afa54e4
--- /dev/null
+++ b/platforms/macos/Sources/AppState+AutoKill.swift
@@ -0,0 +1,60 @@
+import Foundation
+import Defaults
+
+extension AppState {
+    /// Tracks when ports were first seen (port-pid key → first seen date).
+    /// Stored on AppState as a non-observed property.
+    private static var portFirstSeen: [String: Date] = [:]
+
+    /// Checks auto-kill rules against current ports and kills matches that exceed their timeout.
+    func checkAutoKillRules() {
+        let rules = Defaults[.autoKillRules]
+        guard !rules.isEmpty else { return }
+
+        let enabledRules = rules.filter(\.isEnabled)
+        guard !enabledRules.isEmpty else { return }
+
+        let now = Date()
+
+        // Update first-seen tracking
+        let currentKeys = Set(ports.map { "\($0.port)-\($0.pid)" })
+        // Remove stale entries
+        Self.portFirstSeen = Self.portFirstSeen.filter { currentKeys.contains($0.key) }
+        // Add new entries
+        for port in ports {
+            let key = "\(port.port)-\(port.pid)"
+            if Self.portFirstSeen[key] == nil {
+                Self.portFirstSeen[key] = now
+            }
+        }
+
+        // Check rules
+        for port in ports {
+            let key = "\(port.port)-\(port.pid)"
+            guard let firstSeen = Self.portFirstSeen[key] else { continue }
+
+            for rule in enabledRules {
+                guard rule.matches(port) else { continue }
+
+                let elapsed = now.timeIntervalSince(firstSeen) / 60.0
+                guard elapsed >= Double(rule.timeoutMinutes) else { continue }
+
+                // Notify and kill
+                if rule.notifyBeforeKill {
+                    NotificationService.shared.notify(
+                        title: "Auto-Kill: \(port.processName)",
+                        body: "Port \(port.port) killed after \(rule.timeoutMinutes) min (rule: \(rule.name))"
+                    )
+                }
+
+                Task {
+                    await killPort(port)
+                }
+
+                // Remove from tracking so we don't re-trigger
+                Self.portFirstSeen.removeValue(forKey: key)
+                break // Only apply first matching rule
+            }
+        }
+    }
+}
diff --git a/platforms/macos/Sources/AppState+PortOperations.swift b/platforms/macos/Sources/AppState+PortOperations.swift
index a783202..585839c 100644
--- a/platforms/macos/Sources/AppState+PortOperations.swift
+++ b/platforms/macos/Sources/AppState+PortOperations.swift
@@ -27,6 +27,10 @@ extension AppState {
 
             // Always update watcher state to keep transition baseline accurate.
             checkWatchedPorts()
+
+            // Check auto-kill rules
+            checkAutoKillRules()
+
             isScanning = false
         } while hasPendingRefreshRequest
 
diff --git a/platforms/macos/Sources/AppState.swift b/platforms/macos/Sources/AppState.swift
index 589cb72..c9988d0 100644
--- a/platforms/macos/Sources/AppState.swift
+++ b/platforms/macos/Sources/AppState.swift
@@ -23,6 +23,9 @@ extension Defaults.Keys {
     // Process type notification filters (rawValues of enabled types, empty = disabled)
     static let notifyProcessTypes = Key<Set<String>>("notifyProcessTypes", default: [])
 
+    // Auto-kill rules
+    static let autoKillRules = Key<[AutoKillRule]>("autoKillRules", default: [])
+
     // Kubernetes-related keys
     static let customNamespaces = Key<[String]>("customNamespaces", default: [])
 
diff --git a/platforms/macos/Sources/Models/AutoKillRule.swift b/platforms/macos/Sources/Models/AutoKillRule.swift
new file mode 100644
index 0000000..5a2f282
--- /dev/null
+++ b/platforms/macos/Sources/Models/AutoKillRule.swift
@@ -0,0 +1,84 @@
+import Foundation
+import Defaults
+
+/// A rule that automatically kills processes matching certain criteria after a timeout.
+struct AutoKillRule: Codable, Identifiable, Hashable, Sendable, Defaults.Serializable {
+    var id: UUID
+    /// Display name for the rule
+    var name: String
+    /// Process name pattern (supports * wildcard, e.g. "node*"). Empty means match any.
+    var processPattern: String
+    /// Specific port to match. 0 means match any port.
+    var port: Int
+    /// Minutes after which the process should be killed
+    var timeoutMinutes: Int
+    /// Whether to notify before killing
+    var notifyBeforeKill: Bool
+    /// Whether this rule is active
+    var isEnabled: Bool
+
+    init(
+        id: UUID = UUID(),
+        name: String = "",
+        processPattern: String = "",
+        port: Int = 0,
+        timeoutMinutes: Int = 30,
+        notifyBeforeKill: Bool = true,
+        isEnabled: Bool = true
+    ) {
+        self.id = id
+        self.name = name
+        self.processPattern = processPattern
+        self.port = port
+        self.timeoutMinutes = timeoutMinutes
+        self.notifyBeforeKill = notifyBeforeKill
+        self.isEnabled = isEnabled
+    }
+
+    /// Checks if this rule matches a given port info.
+    func matches(_ portInfo: PortInfo) -> Bool {
+        // Check port match
+        if port > 0 && portInfo.port != port { return false }
+
+        // Check process pattern match
+        if !processPattern.isEmpty {
+            return matchesGlob(portInfo.processName, pattern: processPattern)
+        }
+
+        // At least one criterion must be specified
+        return port > 0
+    }
+
+    /// Simple glob matching with * wildcard support.
+    private func matchesGlob(_ string: String, pattern: String) -> Bool {
+        let lowered = string.lowercased()
+        let pat = pattern.lowercased()
+
+        if !pat.contains("*") {
+            return lowered == pat
+        }
+
+        let parts = pat.split(separator: "*", omittingEmptySubsequences: false).map(String.init)
+
+        if parts.count == 1 { return lowered == pat }
+
+        // Check prefix
+        if let first = parts.first, !first.isEmpty, !lowered.hasPrefix(first) {
+            return false
+        }
+        // Check suffix
+        if let last = parts.last, !last.isEmpty, !lowered.hasSuffix(last) {
+            return false
+        }
+
+        // Check all parts appear in order
+        var searchStart = lowered.startIndex
+        for part in parts where !part.isEmpty {
+            guard let range = lowered.range(of: part, range: searchStart..<lowered.endIndex) else {
+                return false
+            }
+            searchStart = range.upperBound
+        }
+        return true
+    }
+}
diff --git a/platforms/macos/Sources/Views/Settings/AutoKillSettingsSection.swift b/platforms/macos/Sources/Views/Settings/AutoKillSettingsSection.swift
new file mode 100644
index 0000000..93eef73
--- /dev/null
+++ b/platforms/macos/Sources/Views/Settings/AutoKillSettingsSection.swift
@@ -0,0 +1,170 @@
+import SwiftUI
+import Defaults
+
+struct AutoKillSettingsSection: View {
+    @Default(.autoKillRules) private var rules
+    @State private var editingRule: AutoKillRule?
+    @State private var isAddingRule = false
+
+    var body: some View {
+        SettingsGroup("Auto-Kill Rules", icon: "clock.badge.xmark") {
+            VStack(spacing: 0) {
+                SettingsRowContainer {
+                    VStack(alignment: .leading, spacing: 2) {
+                        Text("Automatically kill processes after a timeout")
+                            .fontWeight(.medium)
+                        Text("Rules are checked on each port scan cycle")
+                            .font(.caption)
+                            .foregroundStyle(.secondary)
+                    }
+                }
+
+                SettingsDivider()
+
+                if rules.isEmpty {
+                    SettingsRowContainer {
+                        HStack {
+                            Text("No rules configured")
+                                .foregroundStyle(.secondary)
+                            Spacer()
+                            Button("Add Rule") {
+                                isAddingRule = true
+                            }
+                            .controlSize(.small)
+                        }
+                    }
+                } else {
+                    ForEach(rules) { rule in
+                        ruleRow(rule)
+                        if rule.id != rules.last?.id {
+                            SettingsDivider()
+                        }
+                    }
+
+                    SettingsDivider()
+
+                    SettingsRowContainer {
+                        HStack {
+                            Spacer()
+                            Button("Add Rule") {
+                                isAddingRule = true
+                            }
+                            .controlSize(.small)
+                        }
+                    }
+                }
+            }
+        }
+        .sheet(isPresented: $isAddingRule) {
+            AutoKillRuleEditor(rule: AutoKillRule(name: "New Rule")) { newRule in
+                rules.append(newRule)
+            }
+        }
+        .sheet(item: $editingRule) { rule in
+            AutoKillRuleEditor(rule: rule) { updated in
+                if let index = rules.firstIndex(where: { $0.id == updated.id }) {
+                    rules[index] = updated
+                }
+            }
+        }
+    }
+
+    private func ruleRow(_ rule: AutoKillRule) -> some View {
+        SettingsRowContainer {
+            HStack {
+                VStack(alignment: .leading, spacing: 2) {
+                    HStack(spacing: 6) {
+                        Circle()
+                            .fill(rule.isEnabled ? .green : .secondary)
+                            .frame(width: 8, height: 8)
+                        Text(rule.name.isEmpty ? "Unnamed Rule" : rule.name)
+                            .fontWeight(.medium)
+                    }
+                    HStack(spacing: 8) {
+                        if !rule.processPattern.isEmpty {
+                            Text("Process: \(rule.processPattern)")
+                        }
+                        if rule.port > 0 {
+                            Text("Port: \(rule.port)")
+                        }
+                        Text("Timeout: \(rule.timeoutMinutes) min")
+                    }
+                    .font(.caption)
+                    .foregroundStyle(.secondary)
+                }
+
+                Spacer()
+
+                HStack(spacing: 8) {
+                    Button {
+                        editingRule = rule
+                    } label: {
+                        Image(systemName: "pencil")
+                    }
+                    .buttonStyle(.plain)
+
+                    Button {
+                        rules.removeAll { $0.id == rule.id }
+                    } label: {
+                        Image(systemName: "trash")
+                            .foregroundStyle(.red)
+                    }
+                    .buttonStyle(.plain)
+                }
+            }
+        }
+    }
+}
+
+// MARK: - Rule Editor
+
+struct AutoKillRuleEditor: View {
+    @Environment(\.dismiss) private var dismiss
+    @State var rule: AutoKillRule
+    let onSave: (AutoKillRule) -> Void
+
+    var body: some View {
+        VStack(spacing: 0) {
+            // Header
+            Text("Edit Auto-Kill Rule")
+                .font(.headline)
+                .padding(.top, 20)
+
+            Form {
+                TextField("Rule Name", text: $rule.name)
+
+                Section("Match Criteria") {
+                    TextField("Process Pattern (e.g. node*, python*)", text: $rule.processPattern)
+                    TextField("Port (0 = any)", value: $rule.port, format: .number)
+                }
+
+                Section("Behavior") {
+                    Stepper("Timeout: \(rule.timeoutMinutes) minutes", value: $rule.timeoutMinutes, in: 1...1440)
+                    Toggle("Notify before killing", isOn: $rule.notifyBeforeKill)
+                    Toggle("Enabled", isOn: $rule.isEnabled)
+                }
+            }
+            .formStyle(.grouped)
+            .frame(minHeight: 280)
+
+            // Actions
+            HStack {
+                Button("Cancel") {
+                    dismiss()
+                }
+                .keyboardShortcut(.cancelAction)
+
+                Spacer()
+
+                Button("Save") {
+                    onSave(rule)
+                    dismiss()
+                }
+                .keyboardShortcut(.defaultAction)
+                .disabled(rule.processPattern.isEmpty && rule.port == 0)
+            }
+            .padding(20)
+        }
+        .frame(width: 420)
+    }
+}
diff --git a/platforms/macos/Sources/Views/Settings/SettingsView.swift b/platforms/macos/Sources/Views/Settings/SettingsView.swift
index a615156..f9173b8 100644
--- a/platforms/macos/Sources/Views/Settings/SettingsView.swift
+++ b/platforms/macos/Sources/Views/Settings/SettingsView.swift
@@ -36,6 +36,9 @@ struct SettingsView: View {
                 // MARK: - Port Forwarding
                 PortForwardingSettingsSection()
 
+                // MARK: - Auto-Kill Rules
+                AutoKillSettingsSection()
+
                 // MARK: - Notifications
                 NotificationsSettingsSection()