fix: remove trailing commas in Swift for Xcode <16.3 compatibility

[mugnimaestra]

Problem

Users with Xcode 16.2 / Swift 6.0.3 (or older) cannot use agent-device because the iOS XCUITest runner fails to compile. The error manifests as:

Error (COMMAND_FAILED): Runner did not accept connection (simctl spawn)

The underlying build failure is:

error: unexpected ',' separator

in multiple Swift files within the ios-runner directory.

Root Cause

SE-0439 (Allow trailing comma in comma-separated lists) was introduced in Swift 6.1(ships with Xcode 16.3+, MayXcode 16.3, released March 31, 2025). The trailing commas in function/initializer argument lists were introduced in commit 9b443c5 (PR # #149, refactor: split RunnerTests into focused files).

Since agent-device distributes Swift source files via npm and compiles them locally on the user's machine, users with Xcode versions prior to 16.3 hit compilation errorsmachine via xcodebuild, users with Xcode versions prior to 16.3 hit compilation errors. The CI (macos-26 runner with Xcode 26) uses Swift 6.1+, so this was not caught.

The CI (macos-26 runner) uses Xcode 26 with Swift 6.1+, so this was not caught.

Fix

Removed 12 trailing commas from function/initializer argument lists across 5 Swift files:

File	Commas Removed
RunnerTests+Snapshot.swift	5
RunnerTests+Transport.swift	2
RunnerTests+CommandExecution.swift	1
RunnerTests+ScreenRecorder.swift	2
RunnerTests.swift	2

All changes are purely comma removals — no functional changes.

Verification

• pnpm build:xcuitest → ** TEST BUILD SUCCEEDED ** (tested on Xcode 16.2 / Swift 6.0.3)
• agent-device press commands now workwork after fix (runner spawns and accepts connections)
• Python scan confirms zero trailing commas remain before closing ) in any Swift file

Suggestion

Consider adding a CI job that builds the XCUITest runner with the minimum supported Xcode version (e.g., Xcode 16.2) to catch future Swift language compatibility regressions, since the runner is compiled on user machines with varying Xcode versions.

References

• SE-0439 Proposal: https://github.com/swiftlang/swift-evolution/blob/main/proposals/0439-trailing-comma-lists.md
• Swift 6.1 Release Blog (official swift.org): https://swift.org/blog/swift-6.1-released/ — "Swift 6.1 extends trailing comma support to tuples, parameter and argument lists..."
• What's new in Swift 6.1 (Hacking with Swift): https://www.hackingwithswift.com/articles/276/whats-new-in-swift-6-1 — "allowed from Swift 6.1 onwards"
• Xcode 16.3 = Swift 6.1 (xcodereleases.com): https://xcodereleases.com/ — Xcode 16.3 Release (16E140), March 31 2025, Swift 6.1 (6.1.0.110.21)
• InfoQ coverage: https://www.infoq.com/news/2025/05/swift-6-1-released/ — "Swift 6.1, included in Xcode 16.3, introduces... support for trailing commas in lists"
• Swift Evolution Monthly (FlineDev): https://www.fline.dev/swift-evolution-monthly-may-november-2024/ — SE-0439 acceptance & review links
• Commit that introduced trailing commas: callstackincubator/agent-device@9b443c5(PR refactor: split RunnerTests into focused files #149)

Problem

Users with Xcode 16.2 / Swift 6.0.3 (or older) cannot use agent-device because the iOS XCUITest runner fails to compile. The error manifests as:

Error (COMMAND_FAILED): Runner did not accept connection (simctl spawn)
The underlying build failure is:

error: unexpected ',' separator
in multiple Swift files within the ios-runner directory.

Root Cause

SE-0439 (Allow trailing comma in comma-separated lists) was introduced in Swift 6.1 (ships with Xcode 16.3+, MayXcode 16.3, released March 31, 2025). The trailing commas in function/initializer argument lists were introduced in commit 9b443c5 (PR # #149, refactor: split RunnerTests into focused files).

Since agent-device distributes Swift source files via npm and compiles them locally on the user's machine, users with Xcode versions prior to 16.3 hit compilation errorsmachine via xcodebuild, users with Xcode versions prior to 16.3 hit compilation errors. The CI (macos-26 runner with Xcode 26) uses Swift 6.1+, so this was not caught.

The CI (macos-26 runner) uses Xcode 26 with Swift 6.1+, so this was not caught.

Fix

Removed 12 trailing commas from function/initializer argument lists across 5 Swift files:

File Commas Removed
RunnerTests+Snapshot.swift 5
RunnerTests+Transport.swift 2
RunnerTests+CommandExecution.swift 1
RunnerTests+ScreenRecorder.swift 2
RunnerTests.swift 2
All changes are purely comma removals — no functional changes.

Verification

pnpm build:xcuitest → ** TEST BUILD SUCCEEDED ** (tested on Xcode 16.2 / Swift 6.0.3)
agent-device press commands now workwork after fix (runner spawns and accepts connections)
Python scan confirms zero trailing commas remain before closing ) in any Swift file
Suggestion

Consider adding a CI job that builds the XCUITest runner with the minimum supported Xcode version (e.g., Xcode 16.2) to catch future Swift language compatibility regressions, since the runner is compiled on user machines with varying Xcode versions.

References

SE-0439 Proposal: https://github.com/swiftlang/swift-evolution/blob/main/proposals/0439-trailing-comma-lists.md
Swift 6.1 Release Blog (official swift.org): https://swift.org/blog/swift-6.1-released/ — "Swift 6.1 extends trailing comma support to tuples, parameter and argument lists..."
What's new in Swift 6.1 (Hacking with Swift): https://www.hackingwithswift.com/articles/276/whats-new-in-swift-6-1 — "allowed from Swift 6.1 onwards"
Xcode 16.3 = Swift 6.1 (xcodereleases.com): https://xcodereleases.com/ — Xcode 16.3 Release (16E140), March 31 2025, Swift 6.1 (6.1.0.110.21)
InfoQ coverage: https://www.infoq.com/news/2025/05/swift-6-1-released/ — "Swift 6.1, included in Xcode 16.3, introduces... support for trailing commas in lists"
Swift Evolution Monthly (FlineDev): https://www.fline.dev/swift-evolution-monthly-may-november-2024/ — SE-0439 acceptance & review links
Commit that introduced trailing commas: 9b443c5 (PR #149)

[Copilot]

Pull request overview

This PR fixes a compilation compatibility issue for users running Xcode versions prior to 16.3 (Swift < 6.1) by removing trailing commas from function/initializer argument lists in the iOS XCUITest runner Swift files. These trailing commas rely on SE-0439, which was only introduced in Swift 6.1. Additionally, a packageManager field is added to package.json.

Changes:

• Removed 12 trailing commas across 5 Swift files in the iOS XCUITest runner to restore compatibility with Xcode < 16.3 / Swift < 6.1
• Added packageManager field to package.json pinning pnpm@10.19.0

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
package.json	Added packageManager field for pnpm version pinning (unrelated to trailing comma fix)
RunnerTests.swift	Removed 2 trailing commas from array literal initializers
RunnerTests+Transport.swift	Removed 2 trailing commas from function call arguments and array literal
RunnerTests+Snapshot.swift	Removed 5 trailing commas from struct initializer argument lists
RunnerTests+ScreenRecorder.swift	Removed 2 trailing commas from dictionary literal initializers
RunnerTests+CommandExecution.swift	Removed 1 trailing comma from function call arguments

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[Copilot]

The packageManager field addition is not mentioned in the PR description, which only describes removing trailing commas from Swift files. This change pins pnpm@10.19.0 and enables Corepack enforcement, which is unrelated to the Swift compatibility fix and could affect other contributors' workflows. Consider either documenting this in the PR description or splitting it into a separate PR.

[thymikee]

We’re running our tests on 26,2 but rely on cache, interesting

[Copilot]

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