diff --git a/packaging/monitor-mode/installer-app/TargetBridgeInstallerEvent.swift b/packaging/monitor-mode/installer-app/TargetBridgeInstallerEvent.swift
new file mode 100644
index 0000000..82e85ad
--- /dev/null
+++ b/packaging/monitor-mode/installer-app/TargetBridgeInstallerEvent.swift
@@ -0,0 +1,62 @@
+import Foundation
+
+enum InstallerCheckState: String, Equatable {
+    case passed = "pass"
+    case warning = "warn"
+    case failed = "fail"
+    case info
+}
+
+struct InstallerEvent: Equatable {
+    var phase: String
+    var code: String
+    var state: InstallerCheckState
+    var message: String
+
+    static func parse(line: String) -> InstallerEvent? {
+        guard line.hasPrefix("TB_EVENT|") else { return nil }
+        let fields = line.split(separator: "|", maxSplits: 4, omittingEmptySubsequences: false)
+        guard fields.count == 5,
+              let state = InstallerCheckState(rawValue: String(fields[3])) else { return nil }
+        return InstallerEvent(
+            phase: String(fields[1]),
+            code: String(fields[2]),
+            state: state,
+            message: String(fields[4])
+        )
+    }
+
+    static func summary(
+        from events: [InstallerEvent],
+        priorityCodes: [String],
+        limit: Int = 5
+    ) -> [InstallerEvent] {
+        guard limit > 0 else { return [] }
+        var latestByCode: [String: InstallerEvent] = [:]
+        events.forEach { latestByCode[$0.code] = $0 }
+
+        var selected: [InstallerEvent] = []
+        var includedCodes = Set<String>()
+        func appendOnce(_ event: InstallerEvent) {
+            guard includedCodes.insert(event.code).inserted else { return }
+            selected.append(event)
+        }
+
+        // A failed or warning check must never be hidden by earlier successful
+        // rows. Show the most recent actionable result first, then fill the
+        // remaining space with the normal high-level summary.
+        for state in [InstallerCheckState.failed, .warning] {
+            for event in events.reversed()
+                where event.state == state && latestByCode[event.code] == event {
+                appendOnce(event)
+            }
+        }
+        for code in priorityCodes {
+            if let event = latestByCode[code] { appendOnce(event) }
+        }
+        for event in events.reversed() where latestByCode[event.code] == event {
+            appendOnce(event)
+        }
+        return Array(selected.prefix(limit))
+    }
+}
diff --git a/packaging/monitor-mode/tests/InstallerEventTests.swift b/packaging/monitor-mode/tests/InstallerEventTests.swift
new file mode 100644
index 0000000..51a4ed0
--- /dev/null
+++ b/packaging/monitor-mode/tests/InstallerEventTests.swift
@@ -0,0 +1,54 @@
+import Foundation
+
+@main
+struct InstallerEventTests {
+    private static var checks = 0
+    private static var failures = 0
+
+    private static func check(_ label: String, _ condition: @autoclosure () -> Bool) {
+        checks += 1
+        if !condition() {
+            failures += 1
+            fputs("FAIL: \(label)\n", stderr)
+        }
+    }
+
+    static func main() {
+        let parsed = InstallerEvent.parse(line: "TB_EVENT|preflight|hardware|pass|iMac18,2")
+        check("event phase parsed", parsed?.phase == "preflight")
+        check("event code parsed", parsed?.code == "hardware")
+        check("event state parsed", parsed?.state == .passed)
+        check("event message parsed", parsed?.message == "iMac18,2")
+        check(
+            "event message preserves separators",
+            InstallerEvent.parse(line: "TB_EVENT|phase|code|info|one|two")?.message == "one|two"
+        )
+        check("ordinary output ignored", InstallerEvent.parse(line: "ordinary output") == nil)
+        check("malformed event ignored", InstallerEvent.parse(line: "TB_EVENT|short") == nil)
+        check("unknown state ignored", InstallerEvent.parse(line: "TB_EVENT|phase|code|maybe|message") == nil)
+
+        let events = [
+            InstallerEvent(phase: "preflight", code: "hardware", state: .passed, message: "hardware ok"),
+            InstallerEvent(phase: "preflight", code: "package", state: .warning, message: "old warning"),
+            InstallerEvent(phase: "preflight", code: "package", state: .passed, message: "package ok"),
+            InstallerEvent(phase: "preflight", code: "architecture", state: .failed, message: "wrong architecture"),
+            InstallerEvent(phase: "readiness", code: "link", state: .warning, message: "using Wi-Fi")
+        ]
+        let summary = InstallerEvent.summary(
+            from: events,
+            priorityCodes: ["hardware", "package", "link"]
+        )
+        check("failure appears first", summary.first?.code == "architecture")
+        check("warning remains visible", summary.dropFirst().first?.code == "link")
+        check("resolved warning is not prioritized", summary.dropFirst(2).first?.code == "hardware")
+        check("summary has no duplicate codes", Set(summary.map(\.code)).count == summary.count)
+        check(
+            "summary limit is enforced",
+            InstallerEvent.summary(from: events, priorityCodes: ["hardware"], limit: 2).count == 2
+        )
+        check("zero limit returns no rows", InstallerEvent.summary(from: events, priorityCodes: [], limit: 0).isEmpty)
+
+        print("installer event tests: \(checks) checks, \(failures) failures")
+        exit(failures == 0 ? 0 : 1)
+    }
+}
diff --git a/packaging/monitor-mode/tests/test_installer_events.zsh b/packaging/monitor-mode/tests/test_installer_events.zsh
new file mode 100755
index 0000000..20ed218
--- /dev/null
+++ b/packaging/monitor-mode/tests/test_installer_events.zsh
@@ -0,0 +1,15 @@
+#!/bin/zsh
+set -euo pipefail
+
+TEST_DIR="${0:A:h}"
+SOURCE_DIR="${TEST_DIR:h}/installer-app"
+BUILD_DIR="$(/usr/bin/mktemp -d /private/tmp/targetbridge-installer-event-tests.XXXXXX)"
+trap '/bin/rm -R "${BUILD_DIR}"' EXIT
+
+/usr/bin/xcrun swiftc \
+    -module-cache-path "${BUILD_DIR}/ModuleCache" \
+    "${SOURCE_DIR}/TargetBridgeInstallerEvent.swift" \
+    "${TEST_DIR}/InstallerEventTests.swift" \
+    -o "${BUILD_DIR}/InstallerEventTests"
+
+"${BUILD_DIR}/InstallerEventTests"