Answer architecture round 3, stability round 2, product-owner round 2 and prose round 1: the CLI renders exactly the template on stdin and adds nothing, --separator defaults to empty, whitespace around JSON is dropped, a lone reference under --format allows one newline, a blank stdin is refused, an unexpected argument names the spelling to use, and the prose names one lone reference

CHANGELOG.md

@@ -27,11 +27,11 @@ replacement, and each removed path, column or flag.
   operand: `{/misc.coordinate.lat as lat}{calc(lat * 60)}`. What `New` refuses is listed
   under [Names](README.md#names).
 - First release: the CLI, the library and the shipped data set.
-- The CLI renders the template on its stdin, `echo '{/sv_SE.person} hihi' | fejkdata`,
-  and takes no operand. A format string keeps every byte, `echo`'s newline included; a
-  JSON template or one reference alone drops one newline ending stdin, `\n` or `\r\n`.
-  One reference alone, `{/users}`, is the record `users` under `--format`. An operand,
-  or nothing piped in, exits 2.
+- The CLI renders exactly the template on its stdin, `echo '{/sv_SE.person} hihi' |
+  fejkdata`, and adds nothing: `echo`'s newline ends the render, and `--separator`
+  defaults to empty. Whitespace around a JSON template is dropped. A lone reference,
+  `{/users}`, is the record `users` under `--format`. An argument other than a flag, an
+  empty stdin, or nothing piped in, exits 2.
 - Table categories: a category JSON naming a `rows` TSV beside it, with the options
   `key`, `name`, `weight` and `parent`; a path selects a row by key or name,
   `misc.territory[SE]`, and descends to a linked table by name, one path drawing each