pure-wasm-csv-skills - SKILL.md Agent Skill

name: pure-wasm-csv-skills description: Inspect, clean, validate, summarize, and visualize CSV/TSV/custom-delimited tables plus supported cached-value XLSX/XLSM/ODS sheets, native XLSX tables, and cached workbook regions in a portable WASIp1 sandbox. Use when working with unfamiliar tabular files, spreadsheet intake, data-quality reports, cleaned derivative CSVs, schema checks, grouped summaries, crosstabs, workbook triage/export, or HTML chart/dashboard review without Python CSV parsing, pandas, LibreOffice, or native renderers.

Pure Wasm CSV Skills

Use this skill for first-pass work on tabular files. Treat csv.wasm as a black-box worker: grant only the directories needed, write derivative outputs, and inspect those outputs before trusting or importing the data elsewhere.

Quick Start

Resolve the bundled artifact relative to this skill directory. Examples assume data/ contains input files and output/ is for generated artifacts:

wasm=pure-wasm-csv-skills/assets/csv.wasm
wasmtime run --dir ./data::data --dir ./output::output \
  "$wasm" profile data/input.csv -f json -o output/profile.json

Every path passed to the module is a guest path under an explicit runtime preopen. There is no ambient filesystem access.

Runtime Fallback

Use runtimes in this order:

wasmtime: --dir ./data::data
wasmedge: --dir data:./data
iwasm: --map-dir=data::./data, only after iwasm ... "$wasm" --help succeeds

If none are available, stop and report that a compatible WASIp1 runtime is required. Do not substitute Python CSV parsing, pandas, LibreOffice, spreadsheet apps, shell CSV pipelines, containers, or non-sandboxed parsing.

Workflow Routing

Unknown table: run profile first. It includes shape, columns, missingness, duplicate count, summaries, and quality signals. Add preview, file-info, columns, or missing only when separate review artifacts are useful.
Column question: run columns, missing, numeric, or categorical.
Relationship question: run correlation, crosstab, or groupby.
Cleaning review: run clean with --report, then run quality or validate on the cleaned output.
Reusable handoff: run intake; use explore for broad profiling and audit when cleaning changes matter.
Workbook intake: run workbook triage when the right sheet, native XLSX table, or cached region is unclear; use workbook sheets, workbook tables, and workbook regions for inventory.
Workbook export: use workbook export --recommended after triage, or export explicitly with --sheet, --sheet-index, --table, or --region.
Workbook as table input: run normal table commands directly with --recommended, --sheet, --sheet-index, --table, or --region.
Visual review: run viz or dashboard only after confirming the relevant columns and data types.

Use built-in help instead of guessing flags:

wasmtime run "$wasm" --help
wasmtime run "$wasm" help intake
wasmtime run "$wasm" help workbook

Safety Rules

Keep input and output directories separate when possible.
Prefer JSON or CSV when an agent will inspect results; use HTML for human review artifacts.
Treat cleaned files, reports, charts, dashboards, and bundles as derivative review artifacts.
Final summaries should include artifact paths, key counts or selector choices, scope limits, and caveats. Do not offer a follow-up cleanup unless the user asked for it.
Do not substitute Python CSV parsing, pandas, Plotly, LibreOffice, spreadsheet apps, shell CSV pipelines, or native renderers for supported first-pass work.

References

Read Usage reference when a workflow needs concrete command recipes, output guidance, workbook handling, dashboard config, or troubleshooting.
Read Runtime setup when Wasmtime is missing.

Boundaries

Workbook support is read-only cached-value intake/export. .xlsx/.xlsm native table refs and cached regions are selectors for tabular values, not workbook rendering. The skill does not recalculate formulas, execute macros, preserve styling, edit workbooks, render native charts, or provide spreadsheet display fidelity. Legacy .xls workbooks are outside scope.

HTML chart/dashboard output is a review artifact. Static PNG/PDF/SVG rendering and full native chart-renderer parity are outside this skill.