JSON repair

Broken JSON in, strict JSON out — plus a list of what had to be fixed.

Repairs (apply in order, conservatively)

1. Strip comments — // line and /* block */.
2. Quote keys — bare identifiers → "key".
3. Normalize quotes — single → double; keep escapes intact.
4. Language literals — True→true, False→false, None/NaN/undefined→null.
5. Trailing commas — drop before } or ].
6. Close the structure — if truncated, close open strings/objects/arrays so it parses; record this as a fix.

Never invent values to fill gaps — a truncated number stays as-is or becomes null, and that choice is recorded. The goal is parseable, not embellished.

Output

{ data: <parsed JSON value>, fixed: [<short labels of each repair applied>], valid: <true if it now parses> }

If the input is already valid, fixed is empty and data round-trips unchanged.