[obvious-autobuild-staging]

Why

Searching or sorting a CSV table in CSVJSON currently acts only as a visual inspection lens — the converted output (JSON / JSONL / SQL / TS) and Copy / Download actions still emit the full, unsorted source table, and users have no way to hide columns without deleting them from their raw input. Power users preparing a filtered or column-subsetted export shouldn't have to destructively mutate their source CSV just to copy or download a slice.

What

Implements AC-11 and Locked Decision D10 from Blueprint art_MJHTha6X:

• projectCsvView (app/src/lib/tableView.ts): Pure helper that serializes the active visibleColIndices header subset and viewRowIndices row subset via serializeCsvRow joined by \n using table.delimiter, preserving RFC 4180 quoting and custom delimiters (\t, ;, |).
• Columns visibility popover (app/src/components/CsvTable.tsx):
  • Adds data-testid="{testId}-columns-button" in the table toolbar opening a dialog popover (data-testid="{testId}-columns-popout") with per-column checkboxes (data-testid="{testId}-column-toggle-{colIndex}", enforcing ≥1 visible column) and a contextual Show all reset button (data-testid="{testId}-columns-reset").
  • Maps DataEditorCore visible columns through visibleColIndices and translates grid column indices back to source colIndex across sorting, inline cell editing, rectangular paste/fill, double-click header rename, column deletion, per-column type override badges, selection aggregates, and selection copy (serializeGridSelection).
• Contextual Apply view to output toggle (CsvTable.tsx → InputPane.tsx / OutputPane.tsx → App.tsx):
  • Appears in the table toolbar (data-testid="{testId}-apply-view", aria-pressed) only when a search filter (query !== ""), sort (sort !== null), or column subset (visibleColIndices.length < table.headers.length) is active.
  • Off by default so table search/sort/column-picking remain non-destructive view lenses unless opted in.
  • In CSV → JSON mode, toggling Apply view to output on feeds projectedInputCsv into convertText so the output pane (JSON / JSONL / SQL / TS), rows · cols status badge, Copy, and Download reflect the exact active table view without mutating raw input.
  • In JSON → CSV mode, toggling Apply view to output on the output CSV table causes Copy and Download to export the projected CSV view.
• Changelog & Build: Adds changelog entry #20 (2026-10-20) and rebuilds app/dist.

Tradeoffs

• Opt-in contextual pill vs. always-on view projection: Kept table search, sort, and column hiding non-destructive by default and surfaced Apply view to output only when a view transform is active (per D10), avoiding surprise partial exports when someone merely searches a table to inspect a row.
• Header-signature reset: hiddenCols resets automatically if the parsed header count or column names change (e.g. uploading a new file or switching examples), while surviving cell edits and in-place single-header renames.

How to Review

• app/src/lib/tableView.ts & app/src/lib/__tests__/tableView.test.ts — projectCsvView implementation and unit tests.
• app/src/components/CsvTable.tsx & app/src/components/CsvTable.test.tsx — Columns popover, visibleColIndices grid-to-source column mapping, and Apply view to output toggle.
• app/src/App.tsx, app/src/components/InputPane.tsx, app/src/components/OutputPane.tsx, & app/src/App.test.tsx — projected CSV wiring for CSV → JSON conversion and JSON → CSV copy/download.

Verification

• cd app && npm run lint — clean
• cd app && npx tsc -b --noEmit — clean
• cd app && npm test — 34 test files, 585 tests passing
• cd app && npm run build && cd .. && bash .github/scripts/verify-seo.sh — passed
• Interactive headless Chromium (agent-browser) verification at 1440×900@2x (tc-11)

Human author: David Boskovic (david@obvious.ai)

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