Issue #119: an unreachable third-party MCP plugin (e.g. blocked/firewalled
endpoint) blocks `dws --help` for ~10s on every CLI invocation, because
plugin discovery happens eagerly during command-tree construction.
Root cause was a stack of timeouts that multiplied under transport failure:
* `transport.Client.Initialize` loops three supported protocol versions on
every error — including dial timeouts and HTTP 5xx — even though those
failure modes are protocol-version-independent. Three loops × the dial
budget = 3× the worst-case startup cost.
* Default `DialContext.Timeout` was 10s, so a single dial against an
unroutable address (e.g. TEST-NET-1) burned the full plugin context.
* `registerHTTPServer` granted plugins with `AuthHeaders` a 10s outer
context (intended for slow third-party services), and `registerStdioServer`
granted every stdio plugin 10s. Either single misbehaving plugin therefore
stalled the entire CLI.
* Registry-side `defaultDiscoveryTimeout` (10s) and `perServerDiscoveryTimeout`
(5s) had the same shape on the LoadCatalog path.
Changes:
* `transport.Client.Initialize`: short-circuit when the underlying
`*CallError.Stage` is anything other than `CallStageJSONRPC`. Protocol
version negotiation is the only justification for retrying with another
version; transport/HTTP failures fail identically and should surrender.
* `transport.defaultTransport`: `DialContext.Timeout` 10s → 3s.
* `app.registerHTTPServer`: AuthHeaders timeout 10s → 4s.
* `app.registerStdioServer`: outer ctx timeout 10s → 4s.
* `cli.defaultDiscoveryTimeout`: 10s → 4s.
* `discovery.Service`: rename `perServerDiscoveryTimeout` 5s → 2s
(`defaultPerServerDiscoveryTimeout`); add `Service.PerServerTimeout`
override field for tests/callers needing a tighter or looser bound.
Tests:
* `TestInitializeShortCircuitsOnHTTPError` — asserts only ONE protocol
version is attempted on HTTP 5xx.
* `TestInitializeShortCircuitsOnDialFailure` — asserts Initialize returns
in <2s on a refused-connection address.
* Existing `TestInitializeNegotiatesProtocolVersion` continues to pass —
JSON-RPC-stage errors still trigger version fallback.
End-to-end measurement with a blackhole plugin
(endpoint=192.0.2.1, AuthHeaders set):
| Variant | median `dws --help` |
| ------------- | ------------------- |
| main | 10.2s |
| PR #121 alone | 9.1s |
| this branch | 3.72s (-63%) |
The `loader.go` and `discovery/service.go` timeout reductions overlap with
PR #121 by @utafrali; see PR description for attribution.
Refs: #119
Supersedes: #121
修雨
df01f36442