HTTP transport: bare close(timer)/flush(sse_stream) resolve to the package's Transport-only methods, breaking SSE delivery

[kalidke]

Two calls in src/transports/http.jl invoke close/flush unqualified, so inside the module they resolve to the package's own Transport-only methods rather than Base, and throw MethodError at runtime. Both are swallowed by an enclosing catch, so they are invisible in normal operation.

The two sites

src/transports/http.jl:242 — in the SSE loop:

timer = Timer(0.1)  # 100ms timeout
while !istaskdone(t) && isopen(timer)
    ...
end
close(timer)        # <-- Timer, not a Transport

MethodError(ModelContextProtocol.close, (Timer(closed, timeout: 0.1 s),), ...)

src/transports/http.jl:546 — writing a response to an SSE stream:

write(sse_stream, event)
flush(sse_stream)   # <-- HTTP.Streams.Stream, not a Transport

MethodError(ModelContextProtocol.flush, (HTTP.Streams.Stream{...},), ...)

The shadowing methods are flush(transport::Transport) (src/transports/base.jl:201), close(transport::HttpTransport) (http.jl:679), and the stdio equivalents.

Why it matters

The close(timer) throw happens inside the SSE stream loop, so it propagates to the outer handler, which logs "SSE stream closed" and runs a finally that deletes the stream from transport.sse_streams. That suggests server→client notification delivery over HTTP SSE is broken — progress notifications, notifications/tasks/status, and logging notifications all ride that path, and all are listed as implemented with "transport-correct delivery (stdio / SSE)".

Caveat on scope of evidence: I have verified that both MethodErrors occur and traced the control flow, but I have not proven end-to-end that no SSE notification is ever delivered. That should be confirmed as part of the fix.

How it surfaced

Observed while dry-running the rebuilt Inspector workflow (#70) against examples/simple_http_server.jl — the errors appear as level: info MCP log notifications on stderr:

"message":"Failed to write to SSE stream","error":"MethodError(ModelContextProtocol.flush, (HTTP.Streams.Stream{...
"message":"SSE stream closed","error":"MethodError(ModelContextProtocol.close, (Timer (closed, timeout: 0.1 s)...

They reproduce on main (a2508c9) and are unrelated to the Inspector change.

Fix

Qualify both as Base.close(timer) / Base.flush(sse_stream). Note http.jl:264 in the same file already does this correctly (Base.flush(stream)), and CLAUDE.md documents the footgun:

Use Base.flush() explicitly for HTTP streams to avoid naming conflicts

Worth adding a regression test that asserts an SSE notification actually arrives at a connected client, since the suite is currently green (935/935) with these paths throwing — and worth grepping for any other unqualified Base calls shadowed by the package's exports.

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