A stdio server that never answers the optional ping (no -32601, no
response at all) produced a bare TimeoutError that _keepalive_probe
classified as a dead transport, tearing down and respawning a healthy
subprocess on every keepalive tick. On a first ping timeout, confirm with
list_tools before declaring death; if it answers, latch _ping_unsupported
and use list_tools from then on. If both fail, propagate as before.
mcp 2.0.0 implements MCP revision 2026-07-28 and makes three breaking
changes Hermes sits on top of: `mcp.server.fastmcp` is gone, every model
field is renamed to snake_case (camelCase survives only as a
serialization alias, which pydantic does not expose to attribute
access), and the SDK's own HTTP stack moved from `httpx` to `httpx2`.
Bump the pin across the dev/mcp/computer-use extras and port the tree:
- `mcp_serve.py` and `agent/transports/hermes_tools_mcp_server.py` move
from `FastMCP` to `mcp.server.MCPServer`, which has the same
decorator/add_tool surface. The hermes-tools server already
synthesised `__signature__` from Hermes' JSON Schema, which is exactly
what 2.0's `add_tool` reads.
- SDK model reads go through `mcp_field(obj, snake, camel)`, which reads
both spellings. A single-spelling read fails *silently* on the other
generation — empty tool schemas, dropped structured content, tool
results vanishing from sampling conversations — and `mcp` is an
optional extra users install at their own version.
- `sdk_httpx()` resolves the httpx flavour from the SDK's own transport
module, so objects handed to `streamable_http_client`, the `sse_client`
factory, and the OAuth metadata helpers come from the module the
installed SDK actually imports.
- HTTP support is gated on either streamable-HTTP entry point, not just
the deprecated alias 2.0 removed.
- OAuth: `OAuthClientProvider` lost its `timeout` argument (the
configured `oauth.timeout` now bounds the callback waiter's own poll
loop, where the browser round-trip was always awaited), and
`callback_handler` must return `AuthorizationCodeResult` rather than a
tuple. 2.0 also validates the RFC 9207 `iss` parameter, so the
callback handler and paste fallback capture it.
`mcp`/`mcp-types` 2.0.0 are inside the 14-day `exclude-newer` window, so
two narrow `exclude-newer-package` entries unblock `uv lock`, annotated
for removal on or after 2026-08-11. `httpx2` needs no exemption: 2.7.0 is
already outside the window and satisfies mcp's floor.
Refs #69931
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Second, deeper pass over tools/gateway/hermes_cli plus first pass over
the trees wave 1 missed (acp, acp_adapter, skills, computer_use, docker,
dashboard, conformance, monitoring, secret_sources, hermes_state,
providers). Same rubric as wave 1 (AGENTS.md test policy); security,
alternation/caching invariants, issue-number regressions, and E2E kept.
Real test-quality fixes found and rooted out along the way:
- tests/tools/test_command_guards.py made real auxiliary-LLM HTTPS calls
(DEFAULT_CONFIG smart-approval leaked in) — pinned approval
mode=manual via autouse fixture: 17.4s → 0.4s.
- test_model_switch_custom_providers.py / test_user_providers_model_switch.py
silently probed live provider catalogs (~2s/test) — stubbed
cached_provider_model_ids/provider_model_ids/fetch_api_models.
- test_telegram_noise_filter.py: 15-platform copy-paste matrix over
shared gateway.run logic → 3 representative platforms (55s → 3.9s).
- test_gateway_shutdown.py: stop()'s 5s interrupt-deadline loop spun on
MagicMock agents — interrupt.side_effect now clears _running_agents
(22s → 1.0s).
- test_gateway_inactivity_timeout.py poll-harness timings shrunk 3-5x
(24s → 1.1s); test_mcp_stability.py backoff/SIGTERM-grace sleeps
patched (15.4s → 2.5s); test_async_delegation.py negative-drain wait
5s → 0.5s.
- test_telegram_init_deadline.py: loop-block margin restored to 1.0s
with rationale comment — the watchdog-dump assertion needs the loop
blocked well past deadline+grace under parallel load (flaked once in
the 40-worker verification run at a 0.2s margin).
Verification: full hermetic suite via scripts/run_tests.sh —
2,438 files, 21,718 tests passed, 0 failed, 293.9s wall.
Suite totals vs original baseline: 46,820 → 19,757 test functions
(−57.8%), wall 583.5s → 293.9s (−50%), subprocess CPU 13,564s → 11,623s.
Two regression tests for the agentmemory reconnect-loop:
- _is_method_not_found_error matches the plain 'Unknown method: ping'
phrasing (no structural -32601 code).
- _keepalive_probe latches _ping_unsupported and falls back to list_tools
when send_ping raises 'Unknown method: ping', instead of propagating
(which would reconnect-loop).
MCP Streamable HTTP servers that garbage-collect idle sessions on a short
TTL (e.g. Unreal Engine's editor MCP, ~15s) were unusable: the keepalive
was hardcoded at 180s, so the session was always dead by the time it ran,
and every idle tool call then landed on an expired session and paid the
full reconnect path (observed hangs of 113-143s until interrupt, bounded
only by the 300s tool_timeout).
Two coordinated, backward-compatible changes:
- Add per-server `keepalive_interval` (config.yaml, not an env var per the
contribution rubric). Default 180s — byte-identical to the old hardcoded
value when unset — floored at 5s. Servers with short session TTLs set it
below their TTL so the session stays warm.
- Switch the keepalive probe from `list_tools()` to `ping` (the MCP base
protocol liveness primitive). On large servers `list_tools` pulled ~1 MB
every cycle (830 tools = 1,068,041 bytes); `ping` is ~55 bytes and works
uniformly across tool/prompt/resource servers. Tool-list changes still
arrive out-of-band via notifications/tools/list_changed -> _refresh_tools.
`ping` is an OPTIONAL utility, so to guarantee zero regression for a
tool-capable server that doesn't implement it: the first -32601 latches
`_ping_unsupported` and the probe falls back to the pre-ping `list_tools`
path for that connection (no reconnect loop). The latch resets on each
fresh connection (_discover_tools, all transport paths) so a server that
gains ping support after a reconnect is re-probed with the cheap path.
Non-(-32601) ping errors propagate as genuine liveness failures.
Verified end-to-end against a live Unreal MCP server (idle 22s past the
~15s TTL -> post-idle tool call returns in 0.31s, no teardown) and with a
simulated ping-less tool server driving the real keepalive loop (ping once,
list_tools thereafter, no reconnect). 25/25 unit tests pass.
Note: a separate upstream defect (modelcontextprotocol/python-sdk#2604)
still tears down the whole session when one tool-call POST returns 4xx;
that is not addressed here.
Port from anomalyco/opencode#31271: only call tools/list when the server
advertises the 'tools' capability in InitializeResult.capabilities.
Previously, _discover_tools() unconditionally called session.list_tools()
right after initialize. Prompt-only / resource-only servers (which omit
the tools capability per the MCP spec) raise McpError(-32601 Method not
found), which aborted the connection — burning all 3 initial-connect
retries and permanently failing the server even though its prompts and
resources were perfectly usable. The 180s keepalive had the same problem:
it probed with list_tools(), so even a successfully connected prompt-only
server would be torn down on the first keepalive cycle.
Changes:
- MCPServerTask._advertises_tools(): capability check with a legacy
fallback (no captured InitializeResult -> behave as before)
- _discover_tools(): skip tools/list for non-tool servers
- keepalive: use the universal ping request for non-tool servers
- _refresh_tools(): guard against tools/list_changed from non-tool servers
E2E verified with a real stdio prompt-only FastMCP-style server: on main
it fails all 3 connection attempts with Method-not-found; with this fix
it connects, lists prompts, answers ping keepalives, and shuts down
cleanly.
codexbt