Build a useful investigation brief
Build a coordinate fixture matrix
Place one invalid value after a header, an introductory line, and a multiline field in separate controlled files. Record physical lines, logical record numbers, and column positions independently. Include a repeated label or renamed mapping where relevant so the comparison can distinguish row numbering from ambiguous field identification.
Trace location metadata with the value
Follow the failing value from parsing through normalization, mapping, and validation. Record which source coordinates survive at each stage and which are recomputed. Look for an index from a filtered or sampled collection being presented as the original file row without accounting for earlier skipped or combined records.
Compare rendered error references
Inspect how the validation result becomes a message, preview highlight, or downloadable error record. Compare the coordinates and source labels with the fixture. A correct internal location can still be shifted during presentation, while an accurate destination field label may need additional source mapping context to be useful for correction.
What to carry forward
Produce a coordinate trace, smallest failing layout, and first lost or reinterpreted reference. Propose a change that preserves source location and explains its numbering convention. Keep message clarity separate from coordinate correctness so a wording improvement cannot be reported as repairing a still-incorrect pointer to the source value.
Technical background: DuckDB documentation.
Keep the decision with the work.
Use a Work Item in Aglet to record the problem, the evidence you have, and the next decision. Add an owner and priority, then keep updates in the discussion so the next person can follow the reasoning.
Create an account See the product workflow