[codex] Harden Quick Look preview sandbox#385
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schuyler merged 2 commits intoApr 19, 2026
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Nice layered hardening — CSP + disabled JS + nav-cancel + entitlement drop is solid defense in depth, and I like that tests cover both the CSP presence and the absence of embedded Prism scripts. A few non-blocking observations:
None of these are blockers — LGTM. Generated by Claude Code |
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## Summary - Add MacDownCore (framework) and MacDownQuickLook (app extension) as native targets in the Xcode project - Wire CocoaPods dependencies for both targets - Embed the Quick Look extension in the main app bundle - Remove `public.text` from `QLSupportedContentTypes` so the extension only claims markdown files ## Background The Quick Look source code was merged in PRs #299, #368, and #385 but the Xcode project was never configured to build it. This caused 3000.0.6 to register the QL handler without providing a working preview — worse than the macOS default. ## Key decisions - **Resource copying via script phase**: MacDownCore copies Styles and Prism resources via its own shell script build phase rather than reusing MacDown's PBXFileReferences. Those refs are declared outputs of MacDown's "Fetch Prism Resources" and "Transpile Styles" script phases, which would create a dependency cycle. - **No MacDown→MacDownCore dependency**: The main app only depends on MacDownQuickLook. MacDownCore is embedded inside the extension only, since only the extension uses it. - **Per-configuration bundle IDs**: Debug uses `-debug` suffix to match the parent app's pattern. ## Test plan - [ ] `xcodebuild build` succeeds (verified locally) - [ ] 1003 tests pass with 0 unexpected failures (verified locally) - [ ] `.app` bundle contains `MacDownQuickLook.appex` in `Contents/PlugIns/` (verified locally) - [ ] `MacDownQuickLook.appex` contains `MacDownCore.framework` with `Styles/` and `Prism/` resources (verified locally) - [ ] Quick Look preview renders markdown files in Finder - [ ] Quick Look does NOT activate for `.txt`, `.csv`, or other non-markdown text files Related to #284
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## Summary - Add MacDownCore (framework) and MacDownQuickLook (app extension) as native targets in the Xcode project - Wire CocoaPods dependencies for both targets - Embed the Quick Look extension in the main app bundle - Remove `public.text` from `QLSupportedContentTypes` so the extension only claims markdown files ## Background The Quick Look source code was merged in PRs #299, #368, and #385 but the Xcode project was never configured to build it. This caused 3000.0.6 to register the QL handler without providing a working preview — worse than the macOS default. ## Key decisions - **Resource copying via script phase**: MacDownCore copies Styles and Prism resources via its own shell script build phase rather than reusing MacDown's PBXFileReferences. Those refs are declared outputs of MacDown's "Fetch Prism Resources" and "Transpile Styles" script phases, which would create a dependency cycle. - **No MacDown→MacDownCore dependency**: The main app only depends on MacDownQuickLook. MacDownCore is embedded inside the extension only, since only the extension uses it. - **Per-configuration bundle IDs**: Debug uses `-debug` suffix to match the parent app's pattern. ## Test plan - [ ] `xcodebuild build` succeeds (verified locally) - [ ] 1003 tests pass with 0 unexpected failures (verified locally) - [ ] `.app` bundle contains `MacDownQuickLook.appex` in `Contents/PlugIns/` (verified locally) - [ ] `MacDownQuickLook.appex` contains `MacDownCore.framework` with `Styles/` and `Prism/` resources (verified locally) - [ ] Quick Look preview renders markdown files in Finder - [ ] Quick Look does NOT activate for `.txt`, `.csv`, or other non-markdown text files Related to #284
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Summary
Why
Quick Look was rendering attacker-controlled Markdown into a live WKWebView with script execution paths and outbound network capability. A malicious file previewed in Finder could execute JavaScript and exfiltrate document content without opening the main app.
Root cause
The Quick Look path reused the normal rendered HTML body, appended executable Prism scripts, left WebKit JavaScript enabled, and shipped a sandbox entitlement for outbound network access.
Validation
xcodebuild test -workspace "MacDown 3000.xcworkspace" -scheme MacDown -destination "platform=macOS"