Plugin authors had no easy way to figure out why their plugin wasn't
loading — failures were buried in agent.log at WARNING and skip reasons
(disabled, not enabled, depth cap, exclusive) were DEBUG-only and
invisible by default.
Set HERMES_PLUGINS_DEBUG=1 to attach a stderr handler at DEBUG to the
hermes_cli.plugins logger only. Surfaces:
- which directories were scanned + manifest counts per source
- per manifest: resolved key, name, kind, source, on-disk path
- skip reasons (disabled, not enabled, exclusive, depth cap, no register)
- per load: tools/hooks/slash/CLI commands the plugin registered
- full traceback on YAML parse failure (exc_info on the existing warning)
- full traceback on register() exceptions, pointing at the plugin author's line
Env var off (default) → zero new stderr output, same as before.
Touches only hermes_cli/plugins.py + a doc section in the plugin-build
guide + an entry in the env-vars reference. 3 new tests lock the
attach/idempotent/no-attach behavior.
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