PR Description

Reason for Change

The TimeSeries component was failing to parse timestamps with inconsistent fractional second precision (e.g., .0, .5, .12) when using D3's utcParse function. This caused parsing failures and prevented proper visualization of time series data.

Problem: D3's time parsing expects consistent decimal precision, but real-world timestamp data often has varying fractional seconds (1, 2, or 3 digits).

Solution: Implement automatic padding of fractional seconds to exactly 3 decimal places before D3 parsing, ensuring consistent format while preserving data integrity.

Screenshots/Evidence

Video demonstration shows the fix in action:

• Before: Timestamps like 2025-07-06 16:35:17.0 and 2025-07-06 16:35:17.5 fail D3 parsing
• After: Timestamps are automatically padded to 2025-07-06 16:35:17.000 and 2025-07-06 16:35:17.500 for successful parsing

Rollout Strategy

• Feature Flag: Uses existing FF_TIMESERIES_SYNC flag
• Backward Compatible: Existing functionality preserved, only adds padding logic
• No Database Changes: Pure frontend enhancement
• Gradual Rollout: Can be toggled via feature flag if needed

Testing

Unit Tests Added:

• should pad single digit fractional seconds to 3 digits
• should pad two digit fractional seconds to 3 digits
• should leave three digit fractional seconds unchanged
• should handle microseconds and pad remaining digits correctly
• should handle timestamps without fractional seconds
• should handle mixed fractional second formats in the same dataset

Test Coverage:

• Edge cases: 0, 1, 2, 3+ digit fractional seconds
• Mixed datasets with varying precision
• Integration with existing microseconds truncation
• D3 parsing validation with actual timestamp examples

Risks

Low Risk:

• Performance: Minimal overhead - only processes string timestamps
• Data Integrity: Padding preserves original values, only affects display format
• Backward Compatibility: Existing datasets continue to work
• Security: No new attack vectors introduced

Mitigation:

• Comprehensive test coverage for edge cases
• Preserves existing microseconds truncation logic
• Handles mixed precision within same dataset

Reviewer Notes

Key Implementation Details:

• Padding logic added to TimeSeries.jsx dataObj getter (lines ~380)
• Uses regex replacement: /\.(\d{0,3})\b/ to match and pad fractional seconds
• Template literal used for string concatenation (linter compliance)
• Mock environment updated in tests to include required messages property

Code Quality:

• Follows existing patterns in TimeSeries component
• Maintains separation of concerns (parsing vs. display logic)
• Comprehensive error handling for malformed timestamps
• Clean, readable implementation with clear comments

General Notes

Impact:

• Fixes D3 parsing failures for real-world timestamp data
• Improves user experience with TimeSeries visualizations
• Enables proper handling of datasets with inconsistent precision

Technical Details:

• Works alongside existing microseconds conversion (6→3 digits)
• Handles edge cases like timestamps without fractional seconds
• Preserves original data while ensuring D3 compatibility
• No breaking changes to existing API or data format

The implementation successfully addresses the core issue while maintaining code quality and comprehensive test coverage.