Add preview_playground tool and fix build system detection - #38
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Add a playground feature for quick SwiftUI prototyping without any project setup: - preview_playground MCP tool: creates a temp file with provided code (or default skeleton), starts a preview session, returns file path for editing with hot-reload - `previewsmcp playground` CLI command: creates temp file, prints path, starts live preview with file watching - Fix build system detection false positive: fileExists now rejects directories, preventing case-insensitive matches (e.g., ~/workspace/ directory matching Bazel's WORKSPACE marker) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
…tion tests Extract shared helpers (launchMacOSPreview, launchIOSPreview, createPlaygroundFile, defaultPlaygroundCode) into BuildHelpers.swift, eliminating duplicated compile→load→watch logic across MCPServer, RunCommand, and PlaygroundCommand. Extract startMacOSPreview in MCPServer.swift shared by handlePreviewStart and handlePreviewPlayground. Add 3 tests verifying that directories named Package.swift or MODULE.bazel are correctly ignored by SPMBuildSystem and BuildSystemDetector (covers the isDirectory fix). Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
playground now accepts an optional file path to use an existing Swift file instead of creating a temp one. Path is printed to stdout for piping to editors. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
Closes #27. Adds a playground feature for quick SwiftUI prototyping — no project setup needed. Also fixes a build system detection bug found during development.
Playground
preview_playground: Creates a temp Swift file (with provided code or default skeleton), starts a preview session, returns the file path so the agent can edit it for hot-reloadpreviewsmcp playground: Creates a temp file, prints its path, starts a live preview with file watchingBug fix: build system detection false positive
BazelBuildSystem.detectusedFileManager.fileExistswhich returnstruefor directories. On macOS's case-insensitive filesystem, a~/workspace/directory matched Bazel'sWORKSPACEmarker, causing standalone files under~/to fail with a Bazel detection false positive. Fixed in all three detectors (Bazel, SPM, BuildSystemDetector) to reject directories.Test plan
preview_playgroundwith no code — creates default skeleton, renderspreview_playgroundwith custom code — login form renders correctlypreview_starton~/.previewsmcp/playground/no longer falsely detects Bazelswift buildpassesswift test --filter BuildSystem— 37/37 tests pass🤖 Generated with Claude Code