fix(cli): honor an explicit /journey --reveal 0 instead of rendering 100%

[golldyck]

What does this PR do?

Makes an explicit /journey --reveal 0 render the oldest (0%) frame instead of the fully-revealed (100%) one.

_cmd_show (hermes_cli/journey.py) coerces the flag with:

reveal = _clamp(float(getattr(args, "reveal", 1.0) or 1.0), 0.0, 1.0)

--reveal 0 parses (argparse type=float) to 0.0. That's falsy, so or 1.0 swaps it for the default. This is the opposite of what the flag's own help text documents ("0=oldest, 1=now"). It's reachable from both hermes journey --reveal 0 and the interactive /journey --reveal 0. Every other value (0.25, 0.5, …) works, so the failure at the endpoint looks like a rendering bug rather than an argument-parsing one.

The fix treats only a missing value as the fully-revealed default. 0.0 clamps through unchanged.

Related Issue

None filed; introduced with the /journey feature (#55555).

Type of Change

• Bug fix (non-breaking change which fixes an issue)

Changes Made

• hermes_cli/journey.py: replace the falsy-swallowing or 1.0 with an explicit None-check (plus a comment).
• tests/hermes_cli/test_journey_render.py: 3 contract tests that run the real args.func path and assert the reveal value that reaches the frame renderer. --reveal 0 gives 0.0, no flag gives 1.0, and --reveal 0.25 passes through.

How to Test

scripts/run_tests.sh tests/hermes_cli/test_journey_render.py

test_reveal_zero_renders_oldest_frame fails on current main (renderer receives 1.0) and passes with the fix. The other 4 tests, including the two pre-existing ANSI-routing contracts, pass on both. macOS 15. scripts/check-windows-footguns.py clean.

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (N/A, behavior now matches the existing help text)
• My changes generate no new warnings
• I have added tests that prove my fix is effective
• New and existing unit tests pass locally with my changes

[teknium1]

Thanks for the focused regression fix. Current main still applies the falsy fallback at hermes_cli/journey.py:209, while the option documents 0=oldest at hermes_cli/journey.py:316-321. Both hermes journey and interactive /journey use register_cli() and invoke the parsed args.func (hermes_cli/main.py:13383-13397; hermes_cli/cli_commands_mixin.py:314-330), so the change covers both reported paths.

The added tests exercise the real parser/function route and assert the renderer receives 0.0, 1.0, and a fractional value. No changes requested.

Automated hermes-sweeper review.