fix: Show container STARTED time in local timezone

Sources/ContainerCommands/Container/ManagedContainer+ListDisplayable.swift

@@ -32,7 +32,7 @@ extension ManagedContainer: ListDisplayable {
             status.networks.map { $0.ipv4Address.description }.joined(separator: ","),
             "\(configuration.resources.cpus)",
             "\(configuration.resources.memoryInBytes / (1024 * 1024)) MB",
-            status.startedDate?.ISO8601Format() ?? "",
+            status.startedDate?.ISO8601Format(.iso8601(timeZone: .current).timeZone(separator: .colon)) ?? "",
         ]
     }
 

Tests/ContainerCommandsTests/ListFormattingTests.swift

@@ -254,13 +254,105 @@ struct JSONOptionsTests {
 // MARK: - ManagedContainer conformance tests
 
 struct ManagedContainerDisplayTests {
+    /// Builds a minimal `ManagedContainer` for table rendering tests.
+    private func makeManagedContainer(startedDate: Date? = nil) -> ManagedContainer {
+        let image = ImageDescription(
+            reference: "docker.io/library/alpine:latest",
+            descriptor: .init(
+                mediaType: "application/vnd.oci.image.manifest.v1+json",
+                digest: "sha256:" + String(repeating: "0", count: 64),
+                size: 0
+            )
+        )
+        let process = ProcessConfiguration(
+            executable: "/bin/sh",
+            arguments: [],
+            environment: [],
+            workingDirectory: "/",
+            terminal: false,
+            user: .id(uid: 0, gid: 0),
+            supplementalGroups: [],
+            rlimits: []
+        )
+        let configuration = ContainerConfiguration(id: "tz-test", image: image, process: process)
+        let status = ContainerStatus(state: .running, networks: [], startedDate: startedDate)
+        return ManagedContainer(configuration: configuration, status: status)
+    }
+
     @Test
     func tableHeaderHasNineColumns() {
         #expect(ManagedContainer.tableHeader.count == 9)
         #expect(ManagedContainer.tableHeader[0] == "ID")
         #expect(ManagedContainer.tableHeader[4] == "STATE")
         #expect(ManagedContainer.tableHeader[8] == "STARTED")
     }
+
+    @Test
+    func startedColumnIsEmptyWhenContainerNeverStarted() {
+        let row = makeManagedContainer(startedDate: nil).tableRow
+        #expect(row.count == ManagedContainer.tableHeader.count)
+        #expect(row[8] == "")
+    }
+
+    /// Regression test for https://github.com/apple/container/issues/1684:
+    /// the STARTED column must show wall-clock time in the user's local
+    /// timezone, not UTC.
+    @Test
+    func startedColumnShowsLocalTimeComponents() {
+        // Fixed instant: 2026-06-12 16:18:46 UTC.
+        let started = Date(timeIntervalSince1970: 1_781_540_326)
+        let rendered = makeManagedContainer(startedDate: started).tableRow[8]
+
+        var calendar = Calendar(identifier: .gregorian)
+        calendar.timeZone = .current
+        let local = calendar.dateComponents([.year, .month, .day, .hour, .minute, .second], from: started)
+        let expectedPrefix = String(
+            format: "%04d-%02d-%02dT%02d:%02d:%02d",
+            local.year!, local.month!, local.day!, local.hour!, local.minute!, local.second!
+        )
+        #expect(rendered.hasPrefix(expectedPrefix), "expected local wall-clock prefix \(expectedPrefix), got \(rendered)")
+    }
+
+    @Test
+    func startedColumnRoundTripsToSameInstant() throws {
+        let started = Date(timeIntervalSince1970: 1_781_540_326)
+        let rendered = makeManagedContainer(startedDate: started).tableRow[8]
+
+        // Parse with an independent implementation to prove the rendered
+        // string is valid ISO 8601 denoting the same instant.
+        let formatter = ISO8601DateFormatter()
+        formatter.formatOptions = [.withInternetDateTime]
+        let parsed = try #require(formatter.date(from: rendered), "STARTED value must be valid ISO 8601: \(rendered)")
+        #expect(abs(parsed.timeIntervalSince(started)) < 1, "rendered STARTED value must denote the same instant")
+    }
+
+    @Test
+    func startedColumnCarriesLocalUTCOffsetDesignator() {
+        let started = Date(timeIntervalSince1970: 1_781_540_326)
+        let rendered = makeManagedContainer(startedDate: started).tableRow[8]
+
+        let offsetSeconds = TimeZone.current.secondsFromGMT(for: started)
+        if offsetSeconds == 0 {
+            // UTC hosts legitimately render "Z" or a zero offset.
+            #expect(
+                rendered.hasSuffix("Z") || rendered.hasSuffix("+00:00") || rendered.hasSuffix("+0000"),
+                "expected UTC designator, got \(rendered)")
+        } else {
+            // Non-UTC hosts must not render the UTC designator (the pre-fix behavior).
+            #expect(!rendered.hasSuffix("Z"), "STARTED must not be rendered in UTC on non-UTC hosts: \(rendered)")
+            let sign = offsetSeconds < 0 ? "-" : "+"
+            let absOffset = abs(offsetSeconds)
+            let (hours, minutes) = (absOffset / 3600, (absOffset % 3600) / 60)
+            // Foundation renders the offset with or without a colon depending on version.
+            let expectedOffsets = [
+                String(format: "%@%02d:%02d", sign, hours, minutes),
+                String(format: "%@%02d%02d", sign, hours, minutes),
+            ]
+            #expect(
+                expectedOffsets.contains { rendered.hasSuffix($0) },
+                "expected UTC offset suffix in \(expectedOffsets), got \(rendered)")
+        }
+    }
 }
 
 // MARK: - NetworkResource ListDisplayable conformance tests