The symptom: Cursor never leaves “Connecting,” but “the internet works”

If you live inside an AI-first editor, the failure mode is painfully specific. The shell loads, themes apply, and local Git operations feel normal—yet the inline assistant, agent panel, or account handshake stays stuck behind a spinner that simply reads Connecting. Meanwhile a speed test in the browser looks acceptable, and your generic IDE proxy mental model says the tunnel is “up.” That mismatch is the entire story: Cursor is not a single tab on chat.openai.com; it is an Electron application that opens parallel HTTPS sessions, long-lived streams, and a separate path to the extension marketplace stack. When only one of those legs follows the exit you expect, the UI looks broken even though another part of your profile is happily forwarding traffic.

This article is intentionally narrower than our walkthrough on split routing for AI websites in Clash. That piece optimizes browser-first generative AI properties. Here we focus on Clash Cursor scenarios: naming hostnames the desktop client actually uses, placing rules before broad GEOIP shortcuts, and—when you need operational control—splitting marketplace fetches from chat backend traffic so you can tune or troubleshoot them independently.

Why the IDE problem is not the same as “AI sites in Chrome”

Browser workflows reward you when HTML, APIs, and WebSockets share a coherent path, which is why a dedicated AI policy group fixes many ChatGPT-class issues. The Cursor desktop app adds another layer: it bundles editor services, update channels, and third-party extension infrastructure that may not share the same corporate policy story as your favorite web assistant. You might route “OpenAI” sensibly in a browser rule while the editor still reaches model endpoints through vendor-controlled gateways that live on *.cursor.sh-style names. Collapsing everything into one catch-all “AI” group is convenient until marketplace downloads crawl on a node you picked for low chat latency, or until an aggressive domestic rule sends a CDN hostname to DIRECT while the session token expected an offshore path.

Developers also stack tools: Docker pulls, private registries, npm, and SSH sessions all compete for attention in the same profile. If you already followed Docker registry split routing in Clash, you have seen the same principle—narrow rules with a named policy group reduce blast radius. Treat Cursor as another first-class citizen in that zoo, not as a footnote inside “AI websites.”

Anchor list: where the client actually talks (official documentation)

Guessing hostnames from forum screenshots ages poorly. Cursor publishes enterprise-oriented network configuration guidance that enumerates domain patterns worth allowing through firewalls and proxies. According to that documentation, traffic to backend services commonly aligns with patterns such as *.cursor.sh, *.cursor-cdn.com, and *.cursorapi.com, with explicit examples including marketplace.cursorapi.com for marketplace-related access. Authentication flows reference hosts such as authenticate.cursor.sh and authenticator.cursor.sh. Enterprise guidance also highlights api2.cursor.sh as a practical connectivity test target.

Your Clash rules do not need to match firewall allowlists character-for-character, but they should respect the same idea: these names are not interchangeable with “whatever IP GEOIP says.” Pin suffix coverage for the vendor namespace first, then refine. If you maintain a curated RULE-SET, refresh it on a schedule you can defend; silent stale lists are how “it worked yesterday” bugs appear after a vendor rotates an edge name.

Designing policy groups: CURSOR, and when to split marketplace traffic

Start with clarity. Most readers want three knobs that do not fight each other: domestic everyday traffic on DIRECT, a general international default for browsing, and a dedicated group for tooling that must remain stable while you work. Express that as explicit proxy groups in mihomo-class cores rather than one overloaded select list you retune per incident.

A pragmatic default is a single CURSOR select or url-test group referenced by all Cursor-related DOMAIN-SUFFIX lines you care about. That already separates vendor traffic from your generic “international web” bucket and keeps operational notes short: when the assistant misbehaves, you switch exits inside CURSOR without touching Netflix, Docker, or your LAN.

When should you split further? Consider a second group—call it MARKETPLACE—if you observe that extension search, download, or VSIX retrieval consistently prefers a different congestion profile than chat streams. Some teams route bulk artifact traffic through a cheaper relay while keeping interactive AI sessions on a low-latency exit; others keep one group until logs prove a real split is warranted. The goal is not maximal YAML complexity; it is developer split routing you can explain to your future self during an outage.

Rules: put Cursor lines above catch-all geography shortcuts

Clash evaluates rules from top to bottom; the first match wins. Profiles tuned for “fast domestic browsing” often include aggressive GEOIP,CN,DIRECT blocks or community lists that classify large CDN address ranges as onshore. That can be excellent for ordinary sites and catastrophic for a vendor API whose hostname resolves to an anycast front door your rules interpret differently than you expect. The fix is precedence, not superstition: place DOMAIN-SUFFIX entries for cursor.sh, cursorapi.com, and related suffixes above broad geography catches, and keep a short comment when you add an exception “just for one IDE.”

If you are new to the mechanics, read Clash YAML: routing rules, proxy groups, and Fake-IP first—this article assumes you are comfortable reading a rule list as a funnel. Illustrative snippets belong in personal configs, but the invariant is portable: reference your CURSOR group in the lines that matter, document merges carefully, and never assume imported profiles share your IDE priorities.

Extension marketplace proxy behavior: separate symptoms, shared discipline

Extension marketplace traffic is where many “the editor is online but I cannot install anything” reports originate. Search queries, version manifests, and VSIX blobs may hit marketplace endpoints and CDNs that look nothing like the chat stream to api2.cursor.sh. If your logs show marketplace hosts taking a surprising policy, treat that as a routing bug first—not as a reason to reinstall the editor on repeat.

Community workflows sometimes mention Open VSX or Microsoft gallery endpoints when users repoint gallery configuration; your observed hostnames can vary by version and policy. The robust approach remains the same: capture the failing hostname from connection logs, assign it to the policy group you intend, and retest. Guessing from memory is how you “fix” Cursor by accident for ten minutes until the next background update changes the graph.

DNS, TLS, and streaming: why corporate proxies show up in editor issues

Cursor’s own documentation calls out a pattern that pure “rule order” articles miss: many enterprise proxies perform SSL inspection or break HTTP/2 bidirectional streaming. The product may fall back to HTTP/1.1 Server-Sent Events when intermediaries buffer streams—behavior that matters because IDE proxy environments are exactly where security stacks interpose certificates and throttle long connections. If you control the middlebox, follow vendor guidance about inspection exceptions for the documented domain patterns; if you do not, your Clash tunnel might be the only path that preserves end-to-end TLS semantics.

On the DNS side, keep Fake-IP and nameserver-policy stories coherent with the TCP path your Electron binary uses. Split-brain DNS—where the OS resolver and the tun core disagree about a name—is a classic way to get intermittent “Connecting” states that clear when you toggle unrelated settings. When debugging, temporarily simplify upstreams, confirm that suffix rules fire for the expected group, then reintroduce complexity with comments that justify each exception.

System proxy versus TUN: how the editor inherits your stack

Cursor ultimately behaves like other desktop software: it respects the operating system’s proxy settings when configured to do so, and it follows the routes your machine exposes when you run a system-level tunnel. That means your Clash deployment mode matters. A mis-set Windows system proxy port can strand the editor while TUN traffic flows, or vice versa, depending on how the client resolves proxies for its subprocesses. If you recently adjusted modes while chasing another issue, realign modes deliberately rather than stacking toggles.

For Windows-specific TUN pathologies—routes, Defender rules, or conflicts with other VPNs—use Fix Clash TUN on Windows: routing, firewall, and stack conflicts as the companion piece. The point here is integration: Cursor failures are often “last mile” integration failures, not mysterious AI outages.

Verification: logs first, curl tests second, node shopping last

Throughput to a random speed-test server does not predict whether a bidirectional stream survives your chain. Use your GUI’s connection panel to watch which policy matches when the editor touches documented endpoints. If you see an unexpected DIRECT hop for a cursor.sh name, scroll upward in your rules until the precedence story makes sense.

Cursor’s documentation suggests manual curl checks against api2.cursor.sh to validate TLS and streaming behavior through your network path. Those tests are not “Linux trivia”; they distinguish certificate interception from genuine reachability problems. Run them on the same machine and the same proxy mode you use while coding, capture one clean failure, then change one variable at a time.

Quick mapping: what you see versus what to inspect

A brief note on ethics and policy

Proxy tools are infrastructure for transparent, intentional routing. They do not grant permission to violate software terms, workplace acceptable-use policies, or local regulations. Use split routing to make your development environment predictable, not to conceal misuse. When documentation asks you to allow specific domain patterns through security devices, treat that as a coordination task with your administrators rather than a suggestion to punch arbitrary holes.

Closing: give the IDE its own lane

In 2026, AI-assisted coding is mainstream, but the network graph behind your editor is still a specialist concern. A clean Clash setup names its groups, pins vendor suffixes ahead of geography shortcuts, and acknowledges that the extension marketplace is not the same workload as chat—exactly the kind of developer split routing that keeps long sessions boring in the best sense. Compared with opaque clients that hide routing decisions, Clash-family cores reward you with logs you can read when a release changes hostnames overnight.

When you want a maintained desktop experience with a readable connection view alongside modern cores, start from our download page so your client, configuration, and updates stay aligned. Understanding YAML still matters, but you should not fight packaging just to test a CURSOR group. → Download Clash for free and experience the difference.