jq: support --arg and --slurpfile variable bindings

[chubes4]

Summary

The built-in jq command does not recognize the standard --arg or --slurpfile options in just-bash@3.1.0. These options are needed to bind shell values and JSON files into jq filters without interpolating untrusted values into the filter source.

Reproduction

--arg

echo '["Alice", "Bob"]' | jq --arg name Alice '[.[] | select(. == $name)]'

Actual result:

jq: unrecognized option '--arg'

Expected result:

[
  "Alice"
]

--slurpfile

printf '["stdout line"]\n' > /tmp/stdout.json
printf '[]\n' > /tmp/log.json
jq --slurpfile stdout /tmp/stdout.json '. += [{stdout: $stdout[0]}]' /tmp/log.json

Actual result:

jq: unrecognized option '--slurpfile'

Expected result:

[
  {
    "stdout": [
      "stdout line"
    ]
  }
]

Use case

Shell scripts commonly use these bindings to construct structured command logs safely:

jq \
  --arg command "$command" \
  --arg exitCode "$exitCode" \
  --slurpfile stdout "$stdoutJson" \
  '. += [{command: $command, exitCode: ($exitCode | tonumber), stdout: $stdout[0]}]' \
  "$logFile"

Without variable bindings, callers must rewrite valid jq scripts or interpolate shell values into jq source, which is fragile and can introduce injection bugs.

Expected behavior

• --arg name value binds value as a string variable.
• --slurpfile name file parses all JSON values in file and binds them as an array.
• Multiple bindings can be combined in one invocation.
• The behavior works with the browser/VFS implementation as well as the Node entry point.
• Invalid JSON and missing option arguments return jq-compatible nonzero statuses and diagnostics.

Prior report

This overlaps #175, which reported --arg against 2.14.0. That issue was closed by its author without maintainer discussion or a linked implementation. The behavior remains reproducible in 3.1.0, and --slurpfile was not covered there.

[trieloff]

#291 is the likely fix