`hydrate <fixture-path>`

Hydrate a .sheet.json fixture via TestBackend + Sheet.from, then pretty-print the result as a rows × dates grid.

deno run --allow-read --unstable-sloppy-imports \
  tento/tento-lona-js/cli/rows-fixtures/src/lona-rows.deno.ts \
  hydrate tento/tento-lona-js/sheets/tests.shared/sheets/formula-simple-seeded.sheet.json

What it does

Reads the JSON fixture from the given path.
Constructs a TestBackend and seeds it with the fixture.
Calls Sheet.from(rawSheet, { backend }) to build the in-memory model.
Walks sheet.allRows() filtered to SourceRow instances.
For each row, fetches its cells via sheet.stores.sourceCellData.cells(id).
Prints a single grid: bold title, dim row/date count, header row of date keys, separator, then one line per source row.

Output shape

Formula Simple (seeded)
3 rows × 3 dates

                ymd-2026-4-18  ymd-2026-4-19  ymd-2026-4-20
Weight          200.0          —              210.5
Weight Plus 10  210.0          —              220.5  = (+ (rows["Weight"]) 10)
Notes           kept it light  —              —

Conventions:

Bold row labels.
Dim counts ("3 rows × 3 dates").
Cyan = <expression> suffix on FormulaRow rows.
— for empty cells.
Missing rows print nothing (not shown at all).

Date-column dedup

The grid collects every date that appears on any source row; duplicate .toString() outputs collapse to a single column. Two cells with different NaiveDate.Partial types (e.g. day ymd-2026-1-5 + week yw-2026-1) produce distinct columns even if their start DSE overlaps.

Errors

Path doesn't exist → exit code 1, error to stderr.
File isn't valid JSON → exit code 1, parser error to stderr.
File is JSON but not a RawSheet → exit code 1, validation error.
Hydration fails (e.g. unknown row type) → exit code 1, full stack trace.

Use cases

"What does this fixture render to?" — fastest answer.
Diffing two fixture variants side-by-side via diff <(hydrate a) <(hydrate b).
Smoke-checking that a fixture is round-trip clean (compare hydrate output against expected snapshot).