Harden DemoType input processing

[Ryan Waite (ryanwaite)]

Fixes #66

Summary

• clean DemoType control markers without reusing String.Index values after mutation
• bound pause durations and guard nanosecond conversion against overflow
• replay text using complete UTF-16 sequences so non-BMP characters are handled correctly
• add regression coverage for EOF markers, repeated controls, pause bounds, and surrogate pairs

Validation

• swift run ZoomItMacSelfTest
• swift run -c release ZoomItMacSelfTest
• swift run -Xswiftc -DZOOMIT_APP_STORE ZoomItMacSelfTest

[Copilot]

🔵 Needs a closer look

Long graphemes may exceed the 20 UTF-16-unit event limit and be truncated.

Pull request overview

Harden DemoType parsing, pause handling, and Unicode text replay with regression coverage.

Changes:

• Removed stale string-index usage during control-marker cleanup.
• Added pause bounds and overflow protection.
• Improved UTF-16 replay and edge-case tests.

File summaries

File	Summary
Sources/ZoomItMacCore/SelfTest/SelfTestRunner.swift	Added regression tests for controls, pauses, and Unicode handling.
Sources/ZoomItMacCore/App/DemoTypeController.swift	Hardened parsing and replay; long graphemes still require chunking to avoid truncation.

Review details

Suppressed comments (1)

Sources/ZoomItMacCore/App/DemoTypeController.swift:557

• CGEvent.keyboardSetUnicodeString is limited to 20 UTF-16 code units per event, but a valid Swift Character can contain more than 20 units (for example, a base scalar followed by many combining marks). Passing the entire grapheme here can truncate that text, so split long input into API-sized chunks without splitting surrogate pairs (and add a regression case for a long grapheme).

            down?.keyboardSetUnicodeString(stringLength: buffer.count, unicodeString: baseAddress)
            let up = CGEvent(keyboardEventSource: source, virtualKey: 0, keyDown: false)
            up?.keyboardSetUnicodeString(stringLength: buffer.count, unicodeString: baseAddress)

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Lite

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[Ryan Waite (ryanwaite)]

Addressed the Unicode event-length concern in adff901. DemoType now posts one CoreGraphics keyboard event pair per Unicode scalar, so each event contains at most two UTF-16 code units and never splits a surrogate pair. The scalar sequence—and therefore combining graphemes longer than 20 UTF-16 units—is preserved across the emitted events.

Added regression coverage for BMP text, a non-BMP emoji, and a 25-scalar combining grapheme. Validation passed with:

• swift run ZoomItMacSelfTest
• swift run -c release ZoomItMacSelfTest
• swift run -Xswiftc -DZOOMIT_APP_STORE ZoomItMacSelfTest

[Copilot]

🟢 Approval recommended

No unresolved blocking issues were identified.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0 new
• Review effort level: Lite