scripts/validate-repository-naming.py: the plain listing pads each name from the command line or stdin by code points, not by the columns a terminal gives it, so a wide or combining name's label column stands out of line (twin of #1034) #1217

Goal: the plain listing of validate-repository-naming.py pads each name by the columns a terminal gives it, so a wide or combining name's label column starts where every other row's does, and an ASCII name prints byte for byte as it does today.

Filed by lane openRepoShape-3, from RV1178's independent review of #1178 (#1034) at fa56168a (#1178 issuecomment-6351653129), its follow-up for scripts/validate-repository-naming.py:1297; the delta review at c4beba19 (#1178 issuecomment-6353960809) is READY and takes the follow-up no further. It did not hold the landing. #1178 is open at c4beba19, and its diff against main ef619c74 leaves this script, templates/family-root/scripts/siblings.py and scripts/repo_shape.py alone, so the defect is on main now. Line numbers are main's at ef619c74.

The listing pads a name by code points

State. _print_classification (scripts/validate-repository-naming.py:1280) prints f" {name:<32} {label}{also}" (:1297). A format width counts code points. The name is a target's: a command-line name or a line of stdin, both through repo_basename (:1258, :1465), printed as it is. _classify_targets prints one such line per target unless --explain or --quiet is given, a name no family classifies as NO FAMILY (:1290-1291). Two existing rows pin the width for ASCII: tests/test_chain_link_fold.py:175 and :266 assert f"{'codexGlass':<32} ...".

What happens. Arithmetic from the code and the standard library's unicodedata, not a run of the tool: RV1178 measured adopt-project.py's table and listed this one as a follow-up without a measurement. Under the rule #1178 uses (no column for categories Mn, Me and Cf, two for East Asian width W or F, one otherwise):

• a name of the three characters U+65E5 U+672C U+8A9E is 3 code points, so the pad adds 29 spaces and the field is 35 columns wide, 3 more than an ASCII name's 32: its label starts 3 columns to the right of every other row's;
• e U+0301 cole is 6 code points and 5 columns, so its field is 31 columns wide and its label starts 1 column to the left.

On a stdout that cannot hold a character, _escape_what_stdout_cannot_encode (:1262, called at :1452) makes the handler backslashreplace, so U+65E5 reaches the terminal as \u65e5: six columns for one code point that the pad counted once (by reading that function's docstring; not run).

Direction. Pad by display columns, as #1178 does for adopt-project.py's plan table (_columns at adopt-project.py:6437 and _padded at :6460 at c4beba19, with ZERO_COLUMN_CATEGORIES, TWO_COLUMN_WIDTHS and the two Hangul jamo sets), and measure the text as stdout will write it. An ASCII name keeps its width exactly; a name wider than 32 columns is left as it is. No command and no flag.

• This script already imports from scripts/repo_shape.py (:146), the library the roots carry, so one helper there could serve this script, siblings.py (templates/family-root/scripts/siblings.py: the layout table pads each member's name by code points, not by the columns a terminal gives it, so a wide or combining name's state column stands out of line (the family-root twin of #1034) #1216, for its layout table) and, later, adopt-project.py's _columns. The cost is that siblings.py must also run beside an older kept repo_shape.py (its comment at :1520-1524), so the writer decides once, and the PR says where the rule lives.

• :795 and :919 also pad family['id'] to 18 code points. A family id is a policy's word, and whether a policy can name one outside ASCII was not read for this issue: the writer reads that before leaving them.

• The test is tests/test_chain_link_fold.py, whose row at :262-266 already runs this script as run_script(REPO / "scripts" / "validate-repository-naming.py", "--role", "assembly", "--pins", pin, "codexGlass", cwd=tmp_path) and compares the whole stdout. The new rows give it a wide name and a combining one and read the line raw.

• A name of U+65E5 U+672C U+8A9E: its label starts at the same display column as codexGlass's, on a UTF-8 stdout. The row fails before and passes after.

• The same for a name holding e U+0301.

• The same two rows with env={"PYTHONIOENCODING": "ascii:strict"} added to the run (run_script takes env), so the escaped form is counted as stdout writes it.

• An ASCII name prints byte for byte as before: the two existing rows pass unchanged.

• One mutant, the pad back to len, fails a new row; each mutant run is restored and checked with cmp.

Related: #1178, #1034 (adopt-project.py's plan table, the same defect), and #459 (the tracker for setup, scaffold, family and the shared helpers).

Size: S.

Lane: openreposhape-3 (openRepoShape-3)