The docs recommend the file-path form (`--json-schema /path/to/schema.json`)
as primary, but the default-pinned Claude CLI 2.1.160 only accepts an inline
JSON string. Passing a path makes the CLI exit 0 with empty output, so the
action's fail-loud branch trips on every run.
Resolve the value before spawning the CLI: a file-path schema is read
in-process and passed inline (validated + compacted), while an already-inline
schema is left untouched. Because the value is handed to spawn() as an argv
element (never through a shell), a schema with `$ref`/`$defs` round-trips
intact. Unreadable files and invalid JSON now fail with a clear error instead
of the CLI's silent empty output.
Docs (README, example workflow, action.yml) are corrected to explain that the
file-path form is auto-inlined and works on the default CLI.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
reza