Tolerate the row-number quirks foreign generators emit that Excel accepts

Cluster: streaming

Scenario

A user loads an .xlsx produced by a third-party server-side spreadsheet engine, not Excel, directly from a download. The parser throws "Invalid row number" and refuses to open the file. Opening the same file in Excel and re-saving it unchanged makes it load, the canonical signal that the input is within the real-world tolerable envelope even though it trips a strict check.

Spec note, not a corpus case: probing shows this library's current reader already tolerates injected out-of-range and zero row numbers, which load without throwing, but a synthesized fixture may not reproduce the exact <row r> shape the foreign engine emits. Rather than lock a possibly unrepresentative fixture, the durable requirement, to tolerate any row-number quirk Excel tolerates, is captured here. If a real foreign fixture that reproduces the throw surfaces, promote it to a tolerant-read corpus case.

Desired behavior

• Reading a worksheet tolerates the row-index quirks Excel itself tolerates from foreign generators rather than throwing a hard "Invalid row number" that makes an otherwise-valid workbook unopenable.
• When a <row> element carries a missing, empty, zero, or out-of-sequence r attribute, the reader either infers the row number from document order and the row's position in the sheetData stream, or rejects only that individual malformed row while still surfacing the rest of the sheet. It never aborts the whole load.
• If a hard rejection is chosen for a truly invalid value, the error is clear and actionable, naming the offending value and its cell or row context, not a bare "Invalid row number".

Open questions

• Infer-from-position or skip-the-bad-row: which default? Inference preserves more data but can misplace cells if the stream is genuinely disordered.
• What counts as "out of range": clamp to the sheet's 1,048,576-row maximum, or accept and let downstream bounds checks handle it?
• Does the same tolerance apply to column (r or cell address) quirks, or only row numbers?

Related: read-workbook-missing-app-properties, foreign-generator-boolean-and-mixed-sharedstring, streaming-reader-preserves-blank-row-numbers, unsupported-input-format-typed-error.