Slice 6: Error Handling & Edge Cases

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Parent

• PRD: NihongOCR MVP #1 (PRD: NihongOCR MVP)

What to build

Add graceful error handling across the entire stack. Blank captures show "No text detected" instead of an empty window. Tokens with OCR confidence below 0.7 display a subtle orange underline. English-only text passes through without special-casing. Sidecar crashes trigger automatic restart with the splash screen.

This slice hardens the product so edge cases do not confuse or crash the app.

Acceptance criteria

• Blank region capture displays "No text detected" in the Reading window
• English-only text is tokenized and displayed normally
• Tokens with OCR confidence < 0.7 show an orange underline
• Confidence threshold is configurable in code (0.7 default)
• Sidecar crash triggers automatic restart attempt
• On restart, splash screen reappears and app recovers to ready state
• If sidecar fails twice consecutively, show fatal error dialog
• All error states are covered by manual test scenarios

Blocked by

• Slice 3: Real OCR Pipeline (Horizontal Text) #4 (Slice 3: Real OCR Pipeline (Horizontal Text))

Testing notes

Sidecar crash recovery can be tested with mock sidecar processes that exit unexpectedly. Low-confidence and blank-capture scenarios require real or synthetic OCR inputs.