fix(cli): don't flag plugin toolsets as unknown at startup

[byjaps]

What

Every launch reports configured plugin toolsets as unknown, before plugin discovery has had a chance to register them:

$ hermes chat -q "hi" -Q
Warning: Unknown toolsets: voice_stack

HermesCLI._init_toolsets() validates the configured list while the instance is being constructed. Plugins register their toolsets later, during background discovery (discover_plugins()), so judging by the live registry alone (validate_toolset) flags every configured plugin toolset as a typo — even though the very same key set was just used to build enabled_toolsets (via get_plugin_toolset_keys_nowait) two lines earlier in the startup path.

Why it matters beyond the noise

The warning is written to the console, so it lands on stdout for machine-parsed runs. Reproduced case: an integration drives hermes chat -q -Q as a subprocess and reads stdout as the answer, so the warning line was consumed as the reply — in that deployment a TTS pipeline read it out loud instead of the user's answer. --format stream-json is affected the same way (its stdout is meant to be a single JSON object / JSONL stream).

Fix

Skip names the plugin registry reports, mirroring the MCP-server-name exemption already in this block:

try:
    from hermes_cli.plugins import get_plugin_toolset_keys_nowait

    plugin_ts_names = get_plugin_toolset_keys_nowait()
except Exception:
    plugin_ts_names = set()

invalid = [
    t
    for t in toolsets
    if not validate_toolset(t) and t not in mcp_names and t not in plugin_ts_names
]

get_plugin_toolset_keys_nowait() serves the key set persisted by the previous launch's discovery sweep, so the check stays non-blocking on startup (no join on the discovery thread). A genuinely unknown name still warns.

Tests

New TestPluginToolsetStartupValidation in tests/hermes_cli/test_cli_init.py:

• a toolset that a plugin owns but that is not in the live registry yet → no warning, and enabled_toolsets is kept verbatim (the fix silences the warning, it does not drop names);
• a real typo still warns, and the message names the typo only.

Proven RED on base (same tree, only the cli.py hunk reverted):

[100.0% | 45/~45 | ✓1 | ✗1] ✗ tests/hermes_cli/test_cli_init.py (1✓ 1✗, 1.8s)
  ║ >       assert printed == []
  ║ E       AssertionError: assert ['[bold red]W...ice_stack[/]'] == []
  ║ E         Left contains one more item: '[bold red]Warning: Unknown toolsets: voice_stack[/]'

GREEN with the fix:

$ scripts/run_tests.sh tests/hermes_cli/test_cli_init.py tests/tools/test_toolsets.py
=== Summary: 2 files, 70 tests passed, 0 failed, 1 skipped (100% complete) in 15.2s ===

Relation to other work

• Same approach as fix(cli): don't warn on plugin toolsets at startup; accept them in subagent lifecycle #89345 (credit to @adamkrawczyk, added as co-author). That PR no longer applies to main: its agent/subagent_lifecycle.py hunk conflicts (that validation was rewritten upstream), and its startup half is what this PR re-lands against current main.
• test(config): cover enabled plugin toolset discovery during migration #86233 covers the separate config-migration entry point, not this one.
• Still open on main, not addressed here: agent/subagent_lifecycle.py rejects plugin toolsets in allowed_toolsets through the same static-membership test (set(request.allowed_toolsets) - set(TOOLSETS)). Worth a follow-up on the same class of bug rather than widening this PR.
• Also not addressed here: for a real typo the warning still lands on stdout, which breaks the -Q / --format stream-json contract documented in _configure_quiet_agent() ("stdout carries only the final response"). Separate follow-up.

Refs #71650 · Refs #95529 (duplicate report — the one this was reproduced from)

[teknium1]

Thanks @byjaps and @adamkrawczyk — cherry-picked (re-sited onto hermes_cli/cli_init_mixin.py); resolves #71650 / #91757 / #95529.

Salvaged into #118841 with your authorship preserved (merge 74f726c). Thank you!