fix(cli): use Rich [dim] tag instead of ANSI escape in session resume messages

[liuhao1024]

What does this PR do?

Fixes a rich.errors.MarkupError crash when resuming a session whose recorded working directory is missing or inaccessible. The CLI uses Rich's markup system for styled console output, but 4 locations in _restore_session_cwd and _preload_resumed_session injected an ANSI escape code (_DIM = \x1b[2;3m) inside Rich's [...] tag syntax. Rich interprets the escape bytes as an invalid tag, then fails on the matching [/] close tag.

Related Issue

Fixes #39469

Type of Change

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

Changes Made

• cli.py: Replaced [{_DIM}]...[/] with [dim]...[/dim] in 4 locations where _DIM (ANSI escape) was used inside Rich Console.print() markup. This uses Rich's native dim style tag, consistent with existing usage elsewhere in the file (e.g., lines 4322, 4350, 5314).
• tests/cli/test_cli_resume_command.py: Added 3 regression tests covering the missing-directory, chdir-failure, and success paths of _restore_session_cwd.

How to Test

1. Start a session: hermes chat
2. Exit the session
3. Move or delete the directory the session was started from
4. Resume the session: hermes chat -r <session_id>
5. Verify the CLI shows a dim warning instead of crashing with MarkupError
6. Run pytest tests/cli/test_cli_resume_command.py -xvs — all 15 tests pass

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/ -q and all tests pass
• I've added tests for my changes (required for bug fixes, strongly encouraged for features)
• I've tested on my platform: macOS

Documentation & Housekeeping

• I've updated relevant documentation (README, docs/, docstrings) — or N/A
• I've updated cli-config.yaml.example if I added/changed config keys — or N/A
• I've updated CONTRIBUTING.md or AGENTS.md if I changed architecture or workflows — or N/A
• I've considered cross-platform impact (Windows, macOS) per the compatibility guide — or N/A
• I've updated tool descriptions/schemas if I changed tool behavior — or N/A

Code Intelligence

• Analyzed: cli.py:_restore_session_cwd() (lines 5350-5401), cli.py:_preload_resumed_session() (line 5100)
• Callers: _preload_resumed_session called from run(), _restore_session_cwd called from _preload_resumed_session and _do_resume
• Blast radius: LOW — 4 string-literal replacements in a single method; no control flow changes, no API changes
• Related patterns: [dim] Rich tag already used at lines 4322, 4350, 5314 in the same file; _DIM ANSI escape remains safe in _cprint() calls (prompt_toolkit renderer, not Rich)

[tonydwb]

Code Review Summary

Verdict: Approved

Regression fix for a rich.errors.MarkupError that occurred when _restore_session_cwd displayed dimmed warning/info messages using the ANSI escape variable _DIM inside Rich markup strings.

✅ Looks Good

• Root cause is correctly diagnosed: [{_DIM}] is a Rich variable interpolation, but _DIM resolves to a raw ANSI escape (\x1b[2;3m), not a valid Rich tag name — causing a markup parse error.
• Fix replaces [{_DIM}]...[/] with Rich's native [dim]...[/dim] tag, which is the correct approach.
• Three regression tests added covering all affected paths: missing dir, chdir failure, and success case — all assert console.print was called without raising MarkupError.

No concerns

• Minimal, targeted change with no side effects.
• New tests use unittest.mock.MagicMock and unittest.mock.patch correctly.

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Reviewed by Hermes Agent