Agents tunnels: auto-reconnect with backoff and wake-triggered retry#310868
Merged
Agents tunnels: auto-reconnect with backoff and wake-triggered retry#310868
Conversation
Tunnel-backed remote agent hosts previously had no auto-reconnect behavior — on laptop sleep / network drop the tunnel would flip to Disconnected and stay there until the user manually retried. This adds a reconnect loop inside TunnelAgentHostContribution: - Detect Connected→Disconnected transitions for still-cached tunnels and schedule an immediate reconnect. Only fires when the entry is explicitly Disconnected — if the entry has been removed (e.g. user clicked "Remove Remote"), we honour the removal and do not reconnect. - Exponential backoff on consecutive failures: 1s → 30s cap, up to 10 attempts, then pause. - Wake-triggered retry: on browser `online` or tab `visibilitychange` → visible, resume any paused reconnects. Rate-limited to one resume per 10s so rapid tab toggling can't hammer a permanently broken endpoint with unbounded attempt bursts. - Prune all reconnect state when a tunnel is uncached or the contribution is disposed.
Contributor
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Pull request overview
Adds auto-reconnect behavior for tunnel-backed remote agent hosts in the Agents window (vs/sessions), improving resilience to sleep/network drops by retrying tunnel connections with exponential backoff and web wake triggers.
Changes:
- Detects Connected → Disconnected transitions for cached tunnel addresses and schedules reconnect attempts.
- Implements exponential backoff with a max delay cap and a pause after a fixed number of failures.
- Adds web-only wake-triggered resume (
online,visibilitychange) plus reconnect-state pruning/cleanup.
Show a summary per file
| File | Description |
|---|---|
src/vs/sessions/contrib/remoteAgentHost/browser/tunnelAgentHost.contribution.ts |
Adds reconnect state machine (tracking statuses, timers, attempts, pause/resume) and web wake listeners to automatically re-establish tunnel connections. |
Copilot's findings
Comments suppressed due to low confidence (1)
src/vs/sessions/contrib/remoteAgentHost/browser/tunnelAgentHost.contribution.ts:460
_pruneReconnectStateclears timeouts/attempts/pause flags for uncached tunnels, but_previousStatusesis only pruned from_handleConnectionChanges(which doesn’t run on tunnel-cache changes). If a tunnel is uncached and later re-cached without a connection-change event, the stale previous status can cause a spurious Connected→Disconnected transition and immediate reconnect scheduling. Consider also pruning_previousStatusesfor uncached addresses as part of_pruneReconnectState.
/** Drop reconnect state for addresses whose tunnel is no longer cached. */
private _pruneReconnectState(): void {
const cachedAddresses = new Set(
this._tunnelService.getCachedTunnels().map(t => `${TUNNEL_ADDRESS_PREFIX}${t.tunnelId}`)
);
for (const address of [...this._reconnectTimeouts.keys()]) {
if (!cachedAddresses.has(address)) {
this._cancelReconnect(address);
}
}
for (const address of [...this._reconnectAttempts.keys()]) {
if (!cachedAddresses.has(address)) {
this._reconnectAttempts.delete(address);
}
}
for (const address of [...this._reconnectPaused]) {
if (!cachedAddresses.has(address)) {
this._reconnectPaused.delete(address);
}
}
- Files reviewed: 1/1 changed files
- Comments generated: 2
Co-authored-by: Copilot <copilot@github.com>
Contributor
Screenshot ChangesBase: Changed (42)
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Yoyokrazy
approved these changes
Apr 17, 2026
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Summary
Tunnel-backed remote agent hosts previously had no auto-reconnect behavior — on laptop sleep or network drop the tunnel would flip to
Disconnectedand stay there until the user manually retried. This adds a reconnect loop insideTunnelAgentHostContribution.Changes
In src/vs/sessions/contrib/remoteAgentHost/browser/tunnelAgentHost.contribution.ts:
Disconnected— if the entry has been removed from the connection list (e.g. user clicked "Remove Remote"), we honour the removal and do not reconnect.onlineor tabvisibilitychange→ visible, resume any paused reconnects. Rate-limited to one resume per 10s so rapid tab toggling can't hammer a permanently broken endpoint with unbounded attempt bursts. Only clears the attempt counter when the address is actually paused, so in-progress backoff sequences aren't short-circuited.setTimeouts cleared)._connectTunnelnow resets backoff/pause state on success and re-schedules on failure via_scheduleReconnect.Related
Pairs with the
microsoft/vscode-devPR that addsoffline+ long-hidden-resume force-close to the browser tunnel WebSocket.Risk
TunnelAgentHostContribution— does not touch the genericIRemoteAgentHostServicereconnect machinery (which still explicitly skips tunnel entries inreconnect()).isWeb-gated._updateConnectionStatusespath — no new UI surface.Follow-ups (not in this PR)