Pipeline CLIs reject the documented `-` stdin argument (generate-theme, map-tokens, flavian indesign)

[PAMulligan]

Summary

Three InDesign pipeline entry points document - as the "read from stdin"
argument (and their loadIr() helpers are written to handle it), but their
argument-parsing loops reject - as an unknown flag. The advertised stdin form
therefore fails with Unknown argument: - (exit 2). Stdin is still reachable by
omitting the positional argument, so the capability isn't lost — only the
documented - form is broken.

Found while building the new flavian-ingest stage in #146, which handles -
correctly and serves as the reference fix.

Affected entry points

Entry point	Rejects - at	Dead stdin branch
flavian-generate-theme	packages/pipeline/bin/generate-theme.mjs:68	:94
flavian-map-tokens	packages/pipeline/bin/map-tokens.mjs:60	:80
flavian pipeline indesign	bin/flavian.mjs:80	:155

Each one advertises -:

• generate-theme / map-tokens usage string: <ir.json | doc.idml | doc.pdf | ->
• bin/flavian.mjs:86: an input is required (an .idml/.pdf file, an IR JSON, or - for stdin)

flavian-parse-idml and flavian-parse-pdf are not affected — they take a
file path only and intentionally offer no stdin mode.

Reproduction

node tests/fixtures/indesign/emit.mjs ./tmp-fix
node packages/pipeline/bin/ingest.mjs ./tmp-fix/brochure.idml --quiet \
  | node packages/pipeline/bin/generate-theme.mjs - --out-dir ./tmp-theme
# → Unknown argument: -    (exit 2)

• Expected: - is accepted; the IR JSON is read from stdin.
• Actual: Unknown argument: -, usage printed, exit 2.
• Workaround: drop the - (the bins fall back to stdin when no positional is given).

Root cause

The positional-capture guard is !arg.startsWith('-'), and '-'.startsWith('-')
is true, so a bare - is never stored as the input path and falls through to
the unknown-argument branch.

Proposed fix

Treat a bare - as the stdin sentinel before the dash check — exactly what the
merged flavian-ingest bin already does at packages/pipeline/bin/ingest.mjs:53:

// before
if (!inputPath && !arg.startsWith('-')) { inputPath = arg; }
// after — a bare "-" is the explicit stdin sentinel
if (!inputPath && (arg === '-' || !arg.startsWith('-'))) { inputPath = arg; }

Apply the equivalent change in all three entry points. The downstream loadIr()
helpers already special-case inputPath === '-', so no other changes are needed.

Acceptance criteria

• flavian-generate-theme -, flavian-map-tokens -, and flavian pipeline indesign - read the IR from stdin instead of erroring.
• Regression coverage that piping into each entry point via - succeeds (mirror the ingest stdin path).
• Usage/help strings stay consistent (they already advertise -; no doc change expected).
• pnpm --filter @flavian/pipeline test, the InDesign smoke test, and the fixture tests stay green.

References

• Reference fix: PR feat(pipeline): add format-detecting ingest stage with content extraction #146 (flavian-ingest handles - at packages/pipeline/bin/ingest.mjs:53).
• Related: [Redence verify] Pipelines (Data/ETL) — add an IDML/PDF ingest stage to the build pipeline #117 (the ingest-stage work this was found during).