[Repo Assist] Fix #1439: InferRows counts CSV rows, not text lines (multiline quoted fields)

[github-actions]

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Summary

Fixes #1439 — CsvProvider with InferRows = N failed when the sample file contained quoted fields spanning multiple text lines (e.g. "multi-\nline",2). The type provider raised Expected 2 columns, got 1 because the raw text was truncated mid-row.

Root Cause

Helpers.fs → parseTextAtDesignTime used reader.ReadLine() to count rows:

| Some max ->
    let sb = StringBuilder()
    let mutable max = max
    while max > 0 do
        let line = reader.ReadLine()
        if isNull line then max <- 0
        else
            line |> sb.AppendLine |> ignore
            max <- max - 1
    sb.ToString()

This counts text lines, not CSV data rows. A single CSV row containing a quoted multiline field occupies N text lines but should count as just 1 row against the InferRows limit. The truncated string then caused CsvFile.Parse to see an incomplete quoted field, triggering a parse error.

Fix

Pass None as maxNumberOfRows to generateType for CsvProvider. The raw text is no longer pre-truncated by line count. Row limiting during inference is handled correctly by InferColumnTypes which already calls Seq.truncate inferRows — this is the authoritative row limit.

This matches the behaviour of XmlProvider and JsonProvider, which also pass None here.

Performance note: the full sample file is now read into a string at design time. For typical sample files (the intended use — representative excerpts, not production datasets) this is negligible. The CSV row parsing via StringReader remains lazy, so only inferRows rows are actually parsed.

Trade-offs

• Reads the entire sample file text at design time rather than truncating early. For most sample files this is a non-issue.
• Does not change runtime behaviour at all; only affects design-time type inference.

Test Status

✅ New test added: InferRows counts CSV rows not text lines for multiline quoted fields
✅ All 250 existing tests pass (dotnet test tests/FSharp.Data.Tests/FSharp.Data.Tests.fsproj -c Release)

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[github-actions]

✅ Pull request created: #1625