rowspec

A specification and executable conformance suite for tabular data that must survive version control.

A .mdtbl file is a markdown table where a computed column carries its formula in the header, rows have opaque ids, and nothing is addressed by position. The point is that stock git merges it correctly, or refuses — never quietly wrong, with none of this project's tooling installed.

| id     | item   | qty | unit  | total = qty * unit |
| ------ | ------ | --: | ----: | -----------------: |
| r_0001 | widget |  10 | 12.00 |                    |

key   := id
grand := sum(total)

Two branches insert a row far apart. Stock git merge — no driver, no .gitattributes, nothing installed — merges cleanly, and grand is correct. The same table with A1-style references merges just as cleanly and reports a number that is 27% wrong, with no marker anywhere. That difference is the entire project.

What it does not do, measured

If your table is a list of facts, you probably do not need this. We replayed 7,446 real commits from four public CSV-in-git registries, including 528 real three-way merges. Neither .mdtbl nor plain CSV ever merged silently wrong. For an ordinary sorted registry CSV, stock git already does what this format promises, and none of those maintainers has wanted a computed column in four years.

The format earns its keep when a table computes — when a merge can leave a total that is quietly wrong, which is the failure a CSV cannot even represent.

Two branches each adding a column conflict badly, across most of the file. That is inherent to one-row-per-line and it is exactly what happens to a CSV. Nothing here fixes it; a column addition rewrites every row either way.

It is not a data-quality tool. Whether a country code is in ISO 3166, whether a URL resolves, whether a date is plausible — none of that is here, and Frictionless does it well. rowspec asks a smaller question: will this table survive being edited by several people over years?

It runs on the CSV you already have

rowspec check data/

No migration. On an ordinary .csv that alone refuses a committed conflict marker — which Python's own csv module parses as valid rows without complaint — a duplicate column name, a ragged row, invalid UTF-8, and an invisible character in a column name. A five-line data/countries.csv.rowspec.json naming the key and the order column adds the rest. See docs/csv.md, and copy docs/ci/rowspec-check.yml into .github/workflows/.

Run against 1,564 CSVs in three public data repositories it refused 16: two grouped-header spreadsheet exports, thirteen truncated CDC snapshots in owid/covid-19-data whose header declares 14 columns for a 6-field row, and one deliberately broken fixture in iptv-org/database's own test suite. No false positives.

What is actually shipped

The conformance suite is the deliverable. It checks out two branches, runs stock git merge, evaluates the merged file, and asserts on the computed number. No prior art does this. The spec, the validator and the reference implementation exist so the suite has something to check.

410 conformance cases          two implementations, both passing
 76 mutants                    74 killed, 0 survived, 0 stale

The second implementation is the point. reference/rowspec_alt/ was written from SPEC.md alone by an author forbidden to read reference/rowspec/, and it runs against the same fixture tree in CI on every push. It is the only evidence that this document defines the format rather than describing one program, and it has repeatedly been the half that was right: on the last three questions where the two disagreed, the independent implementation was correct and the reference was wrong.

The mutation gate is the other half. The suite is only worth its green tick if it can go red, so the implementation is deliberately broken in 76 specific ways and the suite must notice every one. A mutant that survives is reported as a failure, and so is a stale one whose pattern no longer matches the source — because a check that quietly stopped running is the failure this project keeps finding in itself.

Neither number is a claim about correctness in general. See docs/rationale.md for what has been measured, and what has been measured and found wanting.

Run it

just setup      # uv sync
just check      # fmt-check + lint
just test       # conformance suite + mutation gate + corpus checks
just conform    # the suite alone, against a stock git binary
just mutants    # deliberately break the implementation; the suite must notice
just conform-alt # the SECOND implementation, against the same fixture tree
just run FILE   # validate an artifact (rowspec check)
just eval FILE  # print computed values and FAIL on any #REF!

A real git binary is required. The suite's central claim is about what stock git does, so it uses stock git.

Two commands, and you need both

check applies the refusals in §9 — the structural ones, the things that make a table survive version control. eval computes the table and fails on any #REF!.

They catch different things and neither subsumes the other. A misspelled column name, a pasted 1,299.00, or a non-breaking space in a number are all #REF! under §8 and are correctly not §9 refusals — the file is well-formed, its total is wrong. check alone reports 0 refused on a table whose total is wrong, so a CI recipe built on check is green on a broken total.

Run both:

rowspec check .    # will this table survive being edited by several people?
rowspec eval  .    # does it currently say anything false?

Licensing

Per directory, deliberately — see LICENSE. The fixtures are CC0 so they can be vendored into an implementation in any language under any licence.

Credit

Standing on Coopy/daff, ClassSheets, Object Spreadsheets, Lotus Improv and org-mode. See NOTICE.