Handle Xcode 26 objectVersion 100 project format (synchronized folders)

[Jason-Abbott]

Context

When Xcode 26 opens a project with objectVersion 60, it offers to migrate to objectVersion 100 — the new "synchronized folders" format (PBXFileSystemSynchronizedRootGroup). This migration:

• Replaces explicit PBXFileReference / PBXBuildFile entries with (null) placeholders
• Converts PBXGroup to PBXFileSystemSynchronizedRootGroup
• Removes deprecated keys (buildActionMask, runOnlyForDeploymentPostprocessing, compatibilityVersion, etc.)
• Adds PBXFileSystemSynchronizedBuildFileExceptionSet for excluded files (e.g. Info.plist)

After this migration, local SPM package products (XCLocalSwiftPackageReference) may fail to resolve, producing errors like:

Missing package product 'FooKit' (in target 'Bar' from project 'Baz')

What's missing in xc-mcp

• CreateXcodeprojTool hardcodes preferredProjectObjectVersion: 56 — should use a modern default (77 or 100) or make it configurable
• No tool to validate project integrity after Xcode auto-migration (detect orphaned (null) build files, missing package links, etc.)
• PBXProjWriter and all project tools need testing against objectVersion 100 projects to ensure they can read/write without corruption
• Consider a migrate_project or repair_project tool that can fix common post-migration issues (re-link package products, clean up null references)

Observed in

toba/swiftiomatic — Xcode project opened in Xcode 26, auto-migrated, then failed to build due to missing package products. The committed objectVersion 60 format builds fine.

Summary of Changes

objectVersion default updated (56 → 77)

• CreateXcodeprojTool now defaults to objectVersion 77 (Xcode 15+) and accepts an object_version parameter for 56/77/100
• ScaffoldIOSProjectTool, ScaffoldMacOSProjectTool updated to 77
• TestProjectHelper updated to 77
• compatibilityVersion updated to "Xcode 15.0"

validate_project gains post-migration checks

• Detects null file references in build phases (common Xcode 26 migration artifact)
• Detects orphaned synchronized folders not linked to any target
• Detects broken package product references (missing package link)

New tool: repair_project

• Removes build files with null file references from all build phases
• Removes orphaned PBXBuildFile entries not in any build phase
• Supports dry_run mode to preview fixes without writing
• Registered in both monolithic and xc-project focused servers

Tests

• 6 new RepairProjectTool tests (tool creation, missing params, clean project, null removal, dry run, orphan removal)
• 3 new ValidateProjectTool tests (null file refs, orphaned sync folder, linked sync folder passes)
• All 53 affected tests pass (17 validate, 6 repair, 4 create, 6 scaffold iOS, 8 scaffold macOS, 12 scaffold module)

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