Address code review feedback on _parse_response:
1. Restore isinstance(raw, str) guard so non-string message/reason values
(e.g. integers, lists) from a malformed hook response fall back to the
default rather than being forwarded as-is. This keeps the contract that
message in the returned dict is always a string.
2. Extract the repeated literal 'Blocked by shell hook.' into a module-level
constant _DEFAULT_BLOCK_MESSAGE to avoid duplication and make it easy to
change in one place.
Four new unit tests added to tests/agent/test_shell_hooks.py covering:
- action block with no message (uses default)
- decision block with no reason (uses default)
- action block with empty string message (uses default)
- action block with non-string message, e.g. integer (uses default)
Users can declare shell scripts in config.yaml under a hooks: block that
fire on plugin-hook events (pre_tool_call, post_tool_call, pre_llm_call,
subagent_stop, etc). Scripts receive JSON on stdin, can return JSON on
stdout to block tool calls or inject context pre-LLM.
Key design:
- Registers closures on existing PluginManager._hooks dict — zero changes
to invoke_hook() call sites
- subprocess.run(shell=False) via shlex.split — no shell injection
- First-use consent per (event, command) pair, persisted to allowlist JSON
- Bypass via --accept-hooks, HERMES_ACCEPT_HOOKS=1, or hooks_auto_accept
- hermes hooks list/test/revoke/doctor CLI subcommands
- Adds subagent_stop hook event fired after delegate_task children exit
- Claude Code compatible response shapes accepted
Cherry-picked from PR #13143 by @pefontana.
flamiinngo