Extract PreviewsEngine library target from PreviewsCLI monolith#121
Merged
obj-p merged 2 commits intocli-mcp-parityfrom Apr 16, 2026
Merged
Extract PreviewsEngine library target from PreviewsCLI monolith#121obj-p merged 2 commits intocli-mcp-parityfrom
obj-p merged 2 commits intocli-mcp-parityfrom
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Creates a new `PreviewsEngine` library containing the business logic that has no MCP or ArgumentParser dependency: Moved from MCPServer.swift: - IOSState → IOSSessionManager (public actor) - ConfigCache (public actor) - traitsSummary, formatPreviewList (public functions) - cleanupStaleTempDirs (public function) Moved from BuildHelpers.swift (entire file): - StderrProgressReporter, loadProjectConfig, buildSetupFromConfig, detectAndBuild, resolveDeviceUDID PreviewsEngine depends on PreviewsCore, PreviewsMacOS, PreviewsIOS. It does NOT depend on MCP or ArgumentParser — it can be consumed independently for embedding preview capabilities in any Swift app. Injection changes: - configureMCPServer now takes (host:iosManager:configCache: sharedCompiler:) — all engine instances are injected rather than created internally. - DaemonListener.start creates ONE shared IOSSessionManager and ConfigCache for all connections (preserves session persistence across CLI invocations). - ServeCommand.runStdio creates its own instances (single-connection mode, no sharing needed). - MCPServer.swift stores the injected instances in nonisolated(unsafe) file-private vars (set-once-before-use pattern, Swift 6 requires the annotation). MCPServer.swift is ~100 lines shorter. Everything that remains in it depends on MCP types (CallTool.Parameters, Server, Value). Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Critical: - NoSimulatorError now conforms to LocalizedError with errorDescription (was CustomStringConvertible, which causes localizedDescription to return the generic "operation could not be completed" per AGENTS.md convention). Important: - Removed PreviewsMacOS from PreviewsEngine's Package.swift dependencies — no engine file imports it. Engine stays platform-agnostic. - Deleted orphaned doc comment in MCPServer.swift (leftover from cleanupStaleTempDirs extraction). - Updated DaemonListener doc comment: IOSState → IOSSessionManager, module-level → shared instances. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
PR 1 of the package rearchitecture (plan at
.claude/plans/package-rearchitecture.md). Creates a newPreviewsEnginelibrary target containing business logic that has no MCP or ArgumentParser dependency.What moved to PreviewsEngine
IOSState→IOSSessionManager(public actor)ConfigCache(public actor)traitsSummary,formatPreviewList(public functions)cleanupStaleTempDirs(public function)BuildHelpers.swift(entire file:StderrProgressReporter,loadProjectConfig,detectAndBuild,resolveDeviceUDID,buildSetupFromConfig)What stays in PreviewsCLI
Dependency graph
Injection
configureMCPServer(host:iosManager:configCache:sharedCompiler:)— all engine instances injectedDaemonListener.startcreates ONE sharedIOSSessionManager+ConfigCachefor all connectionsServeCommand.runStdiocreates its own instances (single-connection)Test plan
swift build— cleansimulators,list --json,statusall work through the daemon🤖 Generated with Claude Code