[Bug] dsh-client-connection streamOpenTimeoutMs=3000 causes "Signal timed out" on slow/remote links

[goldenvolcano886-boop]

Environment: dsh web 0.1.0-rc.6 served through a remote tunnel (Tailscale / Cloudflare), phone browser.

Problem: CONNECTION_DEFAULTS.streamOpenTimeoutMs = 3000 — the client aborts the /api/events.mux and /api/events.host stream open after 3 seconds. On slow remote links (mobile VPN / relay) the WebSocket/SSE handshake can take longer than 3s but would succeed; the client hard-fails with "Signal timed out" and the session history fails to load ("历史加载失败"), even though the connection is healthy.

Suggested fix: make the timeout configurable (server-provided or client setting) and/or raise the default (e.g., 15s). Verified that raising it to 15s resolves the failure on a slow mobile link.

[denial123789]

I traced this against the pinned rc.7 source (99f6f02) and found an important distinction for diagnosis: streamOpenTimeoutMs is a readiness guard, not the abort signal passed to /api/events.mux or /api/events.host. When the 3-second sleep wins, Promise.race resolves and the controller can proceed to connected after host.describe(); both stream pumps remain alive. The timer AbortController only cancels the sleep when the streams open early.

Also, the literal Signal timed out does not appear in the pinned Connection package, so the most useful next artifact would be the exact browser stack plus build identity, stream status/close code, and gateway timing. Raising the guard to 15 seconds changing the symptom is valuable ordering evidence, but by itself does not prove that the 3-second guard aborted a healthy stream.

I wrote up the source-backed lifecycle, capture timeline, and regression matrix here: https://sandbaseai.github.io/deepseek-harness-handbook/remote-web-secure-context.html

Relevant source:

deepseek-harness/packages/client/connection/src/client/connection.ts

Lines 108 to 151 in 99f6f02

	while (this.running) {
	const gen = ++this.generation
	const ac = new AbortController()
	this.current = ac
	/* v8 ignore next -- initializer placeholder: the Promise executor
	* below runs synchronously and replaces it before anyone can call it. */
	let muxOpened = (): void => {}
	/* v8 ignore next -- same placeholder pattern as muxOpened. */
	let hostOpened = (): void => {}
	const streamsOpen = Promise.all([
	new Promise<void>((resolve) => { muxOpened = resolve }),
	new Promise<void>((resolve) => { hostOpened = resolve }),
	])
	const failed = new Promise<void>((resolve) => {
	const settle = (): void => {
	if (gen === this.generation && !ac.signal.aborted) ac.abort()
	resolve()
	}
	void this.pumpStream(this.api.events.mux({}, ac.signal, muxOpened), this.sinks.onMuxEnvelope, settle)
	void this.pumpStream(this.api.events.host({}, ac.signal, hostOpened), this.sinks.onHostEnvelope, settle)
	})
	try {
	// Strict readiness handshake: describe proves unary reachability, onOpen
	// proves each physical stream is established before any frame —
	// only then may onConnected fire, so the resync it triggers cannot outrun the
	// subscribed baseline. The timeout guards against a carrier that never fires onOpen
	// (see ConnectionConfig.streamOpenTimeoutMs).
	const timeout = new AbortController()
	const [description] = await Promise.all([
	this.api.host.describe({}),
	Promise.race([streamsOpen, sleep(this.config.streamOpenTimeoutMs, timeout.signal)]),
	])
	timeout.abort()
	const descriptionResult = description.result
	if (!descriptionResult.ok) {
	throw new Error(`host.describe failed: ${descriptionResult.error.code}: ${descriptionResult.error.message}`)
	}
	if (ac.signal.aborted) throw new Error('generation aborted during readiness handshake')
	this.attempt = 0
	this.emitState('connected')
	// A state sink may synchronously stop this controller. Do not publish