The MCP serve event bridge polls two files to decide whether there is new
conversation activity to surface to MCP clients: the gateway sessions.json
index and state.db. Its skip-when-unchanged guard was self-defeating — it
refreshed self._sessions_json_mtime with the current value *before*
comparing against it, so the sessions.json term was always true and the
guard collapsed to a state.db-only check.
The impact is silent message loss on the event stream. The gateway commonly
persists a message to state.db on one tick and registers the owning
conversation in sessions.json a moment later. On that later tick only
sessions.json has changed, so the broken guard takes the early return and
never processes the freshly-registered chat. Its messages are withheld from
every connected MCP client (events_poll / events_wait) until state.db
happens to change again — which, for an otherwise-idle conversation, may be
never. A polling bridge that quietly swallows new conversations is exactly
the failure mode this watcher exists to prevent.
The fix is minimal and low-risk: capture the previously-seen sessions.json
mtime before the cache refresh and compare against that, so the guard skips
only when NEITHER file changed since the last poll. The hot-path mtime
optimization is fully preserved (a genuinely idle tick still short-circuits),
and all existing EventBridge polling tests continue to pass unchanged.
## What does this PR do?
Fixes a logic error in `EventBridge._poll_once` (`mcp_serve.py`) where the
"nothing changed, skip this poll" guard compared `sj_mtime` against
`self._sessions_json_mtime` *after* that attribute had already been
overwritten with `sj_mtime`. The comparison was therefore always true,
reducing the intended "skip only if both files are unchanged" check to a
state.db-only check and discarding any tick in which only sessions.json
changed. The guard now compares against the mtime observed on the previous
poll, restoring the intended behavior.
## Related Issue
N/A
## Type of Change
- [x] 🐛 Bug fix (non-breaking change that fixes an issue)
- [ ] ✨ New feature (non-breaking change that adds functionality)
- [ ] 🔒 Security fix
- [ ] 📝 Documentation update
- [ ] ✅ Tests (adding or improving test coverage)
- [ ] ♻️ Refactor (no behavior change)
- [ ] 🎯 New skill (bundled or hub)
## Changes Made
- `mcp_serve.py`: in `EventBridge._poll_once`, snapshot
`prev_sessions_json_mtime = self._sessions_json_mtime` before refreshing the
cached index, and use it in the skip guard
(`sj_mtime == prev_sessions_json_mtime`) so a sessions.json-only change no
longer triggers the early return. Added a comment explaining the seam.
- `tests/test_mcp_serve.py`: added
`TestEventBridgePollE2E::test_poll_picks_up_new_conversation_when_only_sessions_json_changed`,
a regression test that reproduces the boundary state (state.db unchanged,
sessions.json newly updated) and asserts the new conversation's message is
emitted.
## How to Test
1. Reproduce the failure on the old code: with the guard comparing against
`self._sessions_json_mtime`, the new test fails — the freshly-registered
conversation yields `0` events instead of `1`.
2. Apply the fix and run `pytest tests/test_mcp_serve.py -q` — all 46 tests
pass (40 skipped require the optional `mcp` SDK), including the three
pre-existing `TestEventBridgePollE2E` polling tests and the new regression
guard.
3. `ruff check mcp_serve.py tests/test_mcp_serve.py` and
`python scripts/check-windows-footguns.py mcp_serve.py` both report clean.
## Checklist
### Code
- [x] I've read the [Contributing Guide](https://github.com/NousResearch/hermes-agent/blob/main/CONTRIBUTING.md)
- [x] My commit messages follow [Conventional Commits](https://www.conventionalcommits.org/) (`fix(scope):`, `feat(scope):`, etc.)
- [x] I searched for [existing PRs](https://github.com/NousResearch/hermes-agent/pulls) to make sure this isn't a duplicate
- [x] My PR contains **only** changes related to this fix/feature (no unrelated commits)
- [x] I've run `pytest tests/test_mcp_serve.py -q` and all tests pass
- [x] I've added tests for my changes (required for bug fixes, strongly encouraged for features)
- [x] I've tested on my platform: macOS 15 (Darwin)
### Documentation & Housekeeping
- [x] I've updated relevant documentation (README, `docs/`, docstrings) — or N/A
- [x] I've updated `cli-config.yaml.example` if I added/changed config keys — or N/A
- [x] I've updated `CONTRIBUTING.md` or `AGENTS.md` if I changed architecture or workflows — or N/A
- [x] I've considered cross-platform impact (Windows, macOS) per the [compatibility guide](https://github.com/NousResearch/hermes-agent/blob/main/CONTRIBUTING.md#cross-platform-compatibility) — or N/A
- [x] I've updated tool descriptions/schemas if I changed tool behavior — or N/A
Remove unused imports (F401) and duplicate/shadowed import
redefinitions (F811) across the codebase using ruff's safe
autofixes. No behavioral changes -- imports only.
- ~1400 safe autofixes applied across 644 files (net -1072 lines)
- __init__.py re-exports preserved (excluded from F401 removal so
public re-export surfaces stay intact)
- Re-exports that are imported or monkeypatched by tests but look
unused in their defining module are kept with explicit # noqa:
F401 (gateway/run.py load_dotenv; run_agent re-exports from
agent.message_sanitization, agent.context_compressor,
agent.retry_utils, agent.prompt_builder, agent.process_bootstrap,
agent.codex_responses_adapter)
- Unsafe F841 (unused-variable) fixes deliberately skipped -- those
can change behavior when the RHS has side effects
- ruff lints remain disabled in pyproject.toml (only PLW1514 is
selected); this is a one-time cleanup, not a config change
Verification:
- python -m compileall: clean
- pytest --collect-only: all 27161 tests collect (zero import errors)
- core entry points import clean (run_agent, model_tools, cli,
toolsets, hermes_state, batch_runner, gateway)
- static scan: every name any test imports directly from an edited
module still resolves
channels_list was iterating directory.items() directly, yielding
("updated_at", str) and ("platforms", dict) pairs — neither passed
the isinstance(entries_list, list) check, so the inner loop never ran
and every call returned count=0 even when channel_directory.json was
populated.
The writer (gateway/channel_directory.py) wraps the payload as
{"updated_at": ..., "platforms": {...}}; every other reader in the
codebase unwraps via directory.get("platforms", {}). This aligns
channels_list with that convention.
Also tightens the existing test_channels_with_directory test, which
bypassed the bug by asserting against _load_channel_directory() directly
instead of calling channels_list. It now calls the tool end-to-end and
a new test_channels_with_directory_platform_filter covers the filter
path. Both tests fail against the pre-fix code.
Closes#21474
Co-authored-by: chrisworksai <262485129+chrisworksai@users.noreply.github.com>
hermes mcp serve starts a stdio MCP server that lets any MCP client
(Claude Code, Cursor, Codex, etc.) interact with Hermes conversations.
Matches OpenClaw's 9-tool channel bridge surface:
Tools exposed:
- conversations_list: list active sessions across all platforms
- conversation_get: details on one conversation
- messages_read: read message history
- attachments_fetch: extract non-text content from messages
- events_poll: poll for new events since a cursor
- events_wait: long-poll / block until next event (near-real-time)
- messages_send: send to any platform via send_message_tool
- channels_list: browse available messaging targets
- permissions_list_open: list pending approval requests
- permissions_respond: allow/deny approvals
Architecture:
- EventBridge: background thread polls SessionDB for new messages,
maintains in-memory event queue with waiter support
- Reads sessions.json + SessionDB directly (no gateway dep for reads)
- Reuses send_message_tool for sending (same platform adapters)
- FastMCP server with stdio transport
- Zero new dependencies (uses existing mcp>=1.2.0 optional dep)
Files:
- mcp_serve.py: MCP server + EventBridge (~600 lines)
- hermes_cli/main.py: added serve sub-parser to hermes mcp
- hermes_cli/mcp_config.py: route serve action to run_mcp_server
- tests/test_mcp_serve.py: 53 tests
- docs: updated MCP page + CLI commands reference
