bug: preserve stdout when --json is another option value

[codeforester]

Problem

Raw JSON detection treats an option value as a lifecycle flag. The runner captures stdout; real parsing then correctly leaves JSON disabled, so successful command output is discarded silently.

Verified evidence

Reviewed on 2026-09-12 at 7faf347a5b90969e169c88f3ac18e7202d142dd0; the local checkout matches GitHub main.

With the same attached probe command accepting a string --payload and an optional lifecycle --json, make the callback print PAYLOAD= plus the value.

run_app(command, ["--payload", "--json"])
exit=0, stdout="", stderr=""

run_app(command, ["--payload=--json"])
exit=0, stdout="PAYLOAD=--json\n"

Click accepts the next token as the string option value. _json_requested() scans every raw token without consuming known option arity; _capture_standard_options() later disables JSON but the captured stream is never replayed.

Sources:

• lib/python/base_cli/_run.py
• lib/python/base_cli/_app_core.py

Acceptance criteria

• Respect option values and short-option arity while selecting capture mode.
• The two equivalent payload forms produce identical human stdout and exit status.
• Cover multi-value options, attached short values, flag-like positional data, root/leaf flags, negation, and early parse errors.
• Coordinate with the callback-preflight fix without adding another parsing pass.

Related work

Distinct follow-up to closed #221/#304: this is successful invocation data loss from a value token, not the already-covered -- terminator or short-flag error cases.

Project fields

• Status: Backlog
• Priority: P1
• Area: CLI
• Initiative: v1.0 Readiness
• Size: M
• Assignee: @codeforester
• Milestone: v1.0.0
• Target date: unscheduled

[codeforester]

Released-package comparison: reran the same harmless public-API reproducer in a clean environment installed from PyPI (base-cli==0.4.3, Click 8.4.2). The released package executes the option callback once and preserves PAYLOAD=--json for both string-value spellings. Reviewed main (7faf347a, Click 8.5.0) shows the reported failure. This establishes a regression relative to the released baseline; isolate framework revision from Click version in the fix matrix before assigning the introducing change.

[codeforester]

Dependency-controlled check completed: reviewed main still reproduces this failure after installing Click 8.4.2, matching the released-package environment. The difference is in the framework revision, not a Click 8.5-only behavior.