Share styled OAuth callback page between providers

Richard Feldman created 

Add http_client::oauth_callback_page() that generates a nicely styled
HTML page with Zed branding for OAuth callback responses. Use it in
both the ChatGPT subscription provider and the MCP context server
OAuth flow, replacing the unstyled inline HTML in both places.

The template is parameterized on title and message so both callers
get consistent styling that updates in one place.

Change summary

crates/context_server/src/oauth.rs                       | 12 
crates/http_client/src/http_client.rs                    | 86 ++++++++++
crates/language_models/src/provider/openai_subscribed.rs | 15 +
3 files changed, 104 insertions(+), 9 deletions(-)

Detailed changes

crates/context_server/src/oauth.rs 🔗 

@@ -1107,15 +1107,19 @@ pub async fn start_callback_server() -> Result<(
             let (status_code, body) = match &result {
                 Ok(_) => (
                     200,
-                    "<html><body><h1>Authorization successful</h1>\
-                     <p>You can close this tab and return to Zed.</p></body></html>",
+                    http_client::oauth_callback_page(
+                        "Authorization Successful",
+                        "You can close this tab and return to Zed.",
+                    ),
                 ),
                 Err(err) => {
                     log::error!("OAuth callback error: {}", err);
                     (
                         400,
-                        "<html><body><h1>Authorization failed</h1>\
-                         <p>Something went wrong. Please try again from Zed.</p></body></html>",
+                        http_client::oauth_callback_page(
+                            "Authorization Failed",
+                            "Something went wrong. Please try again from Zed.",
+                        ),
                     )
                 }
             };

crates/http_client/src/http_client.rs 🔗 

@@ -291,6 +291,92 @@ impl HttpClient for HttpClientWithUrl {
     }
 }
 
+/// Generate a styled HTML page for OAuth callback responses.
+///
+/// Returns a complete HTML document (no HTTP headers) with a centered card
+/// layout styled to match Zed's dark theme. The `title` is rendered as a
+/// heading and `message` as body text below it.
+pub fn oauth_callback_page(title: &str, message: &str) -> String {
+    format!(
+        r#"<!DOCTYPE html>
+<html lang="en">
+<head>
+<meta charset="utf-8">
+<meta name="viewport" content="width=device-width, initial-scale=1">
+<title>{title} — Zed</title>
+<style>
+  * {{ margin: 0; padding: 0; box-sizing: border-box; }}
+  body {{
+    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
+    background: #1e1e2e;
+    color: #cdd6f4;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    min-height: 100vh;
+    padding: 1rem;
+  }}
+  .card {{
+    background: #313244;
+    border-radius: 12px;
+    padding: 2.5rem;
+    max-width: 420px;
+    width: 100%;
+    text-align: center;
+    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.3);
+  }}
+  .icon {{
+    width: 48px;
+    height: 48px;
+    margin: 0 auto 1.5rem;
+    background: #a6e3a1;
+    border-radius: 50%;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+  }}
+  .icon svg {{
+    width: 24px;
+    height: 24px;
+    stroke: #1e1e2e;
+    stroke-width: 3;
+    fill: none;
+  }}
+  h1 {{
+    font-size: 1.25rem;
+    font-weight: 600;
+    margin-bottom: 0.75rem;
+    color: #cdd6f4;
+  }}
+  p {{
+    font-size: 0.925rem;
+    line-height: 1.5;
+    color: #a6adc8;
+  }}
+  .brand {{
+    margin-top: 1.5rem;
+    font-size: 0.8rem;
+    color: #585b70;
+    letter-spacing: 0.05em;
+  }}
+</style>
+</head>
+<body>
+<div class="card">
+  <div class="icon">
+    <svg viewBox="0 0 24 24"><polyline points="20 6 9 17 4 12"/></svg>
+  </div>
+  <h1>{title}</h1>
+  <p>{message}</p>
+  <div class="brand">Zed</div>
+</div>
+</body>
+</html>"#,
+        title = title,
+        message = message,
+    )
+}
+
 pub fn read_proxy_from_env() -> Option<Url> {
     const ENV_VARS: &[&str] = &[
         "ALL_PROXY",

crates/language_models/src/provider/openai_subscribed.rs 🔗 

@@ -684,11 +684,16 @@ async fn await_oauth_callback(expected_state: &str) -> Result<String> {
         }
     }
 
-    let html = b"HTTP/1.1 200 OK\r\nContent-Type: text/html\r\n\r\n\
-        <html><body><h1>Signed in to Zed</h1>\
-        <p>Authentication successful. You can close this tab.</p>\
-        </body></html>";
-    stream.write_all(html).await.log_err();
+    let page = http_client::oauth_callback_page(
+        "Signed In",
+        "You've signed into Zed via your ChatGPT subscription. You can close this tab and return to Zed.",
+    );
+    let response = format!(
+        "HTTP/1.1 200 OK\r\nContent-Type: text/html; charset=utf-8\r\nContent-Length: {}\r\n\r\n{}",
+        page.len(),
+        page
+    );
+    stream.write_all(response.as_bytes()).await.log_err();
 
     let received_state =
         received_state.ok_or_else(|| anyhow!("Missing state in OAuth callback"))?;