Implement document title and referrer semantics

crates/obscura-js/src/ops.rs

@@ -74,6 +74,10 @@ pub struct ObscuraState {
     /// encoding override for `<a>`/`<area>` hrefs in legacy-charset documents.
     pub encoding: String,
     pub title: String,
+    /// URL of the document that initiated this document's navigation. Direct
+    /// browser/API navigations leave this empty; document-initiated
+    /// navigations set it to the source document URL.
+    pub referrer: String,
     pub blocked_urls: Vec<String>,
     pub cookie_jar: Option<Arc<CookieJar>>,
     pub http_client: Option<Arc<ObscuraHttpClient>>,
@@ -141,6 +145,7 @@ impl ObscuraState {
             url: "about:blank".to_string(),
             encoding: "UTF-8".to_string(),
             title: String::new(),
+            referrer: String::new(),
             blocked_urls: Vec::new(),
             cookie_jar: None,
             http_client: None,
@@ -350,8 +355,26 @@ fn op_dom_inner(state: &OpState, cmd: String, arg1: String, arg2: String) -> Str
 
     match cmd.as_str() {
         "document_node_id" => dom.document().index().to_string(),
-        "document_title" => serde_json::to_string(&gs.title).unwrap_or("\"\"".into()),
+        "document_title" => {
+            // The DOM is authoritative after parsing. In particular, script
+            // changes through title.textContent must be reflected by
+            // document.title, not hidden behind the navigation-time snapshot.
+            let title = dom
+                .query_selector("title")
+                .ok()
+                .flatten()
+                .map(|title_id| {
+                    dom.text_content(title_id)
+                        .split(|ch| matches!(ch, '\t' | '\n' | '\u{000C}' | '\r' | ' '))
+                        .filter(|part| !part.is_empty())
+                        .collect::<Vec<_>>()
+                        .join(" ")
+                })
+                .unwrap_or_default();
+            serde_json::to_string(&title).unwrap_or("\"\"".into())
+        }
         "document_url" => serde_json::to_string(&gs.url).unwrap_or("\"\"".into()),
+        "document_referrer" => serde_json::to_string(&gs.referrer).unwrap_or("\"\"".into()),
         "document_encoding" => serde_json::to_string(&gs.encoding).unwrap_or("\"UTF-8\"".into()),
         "document_element" => {
             for cid in dom.children(dom.document()) {

crates/obscura-js/src/runtime.rs

@@ -255,6 +255,14 @@ impl ObscuraJsRuntime {
         self.state.borrow_mut().title = title.to_string();
     }
 
+    /// Set the source document URL exposed as `document.referrer`. Navigation
+    /// owns this value; it is not derived from the current URL because direct
+    /// navigations and document-initiated navigations have different
+    /// referrer semantics.
+    pub fn set_referrer(&self, referrer: &str) {
+        self.state.borrow_mut().referrer = referrer.to_string();
+    }
+
     pub fn set_blocked_urls(&self, patterns: Vec<String>) {
         self.state.borrow_mut().blocked_urls = patterns;
     }
@@ -2244,7 +2252,91 @@ mod tests {
     fn test_document_title() {
         let mut rt = setup_runtime("<html><head><title>Test</title></head><body></body></html>");
         let title = rt.evaluate("document.title").unwrap();
-        assert_eq!(title, serde_json::json!("Test Page"));
+        assert_eq!(title, serde_json::json!("Test"));
+
+        let result = rt
+            .evaluate(
+                r#"
+                (function() {
+                  document.title = "A <new> title";
+                  return [
+                    document.title,
+                    document.querySelector("head > title").textContent,
+                    document.querySelectorAll("title").length
+                  ];
+                })()
+                "#,
+            )
+            .unwrap();
+        assert_eq!(
+            result,
+            serde_json::json!(["A <new> title", "A <new> title", 1])
+        );
+
+        let normalized = rt
+            .evaluate(
+                r#"
+                (function() {
+                  document.querySelector("title").textContent = "  live\n\tDOM   title  ";
+                  return document.title;
+                })()
+                "#,
+            )
+            .unwrap();
+        assert_eq!(normalized, serde_json::json!("live DOM title"));
+    }
+
+    #[test]
+    fn document_title_setter_creates_missing_title_element() {
+        let mut rt = setup_runtime("<html><body><main>content</main></body></html>");
+        let result = rt
+            .evaluate(
+                r#"
+                (function() {
+                  document.title = "Created";
+                  return [
+                    document.title,
+                    document.head.tagName,
+                    document.head.firstElementChild.tagName,
+                    document.head.firstElementChild.textContent,
+                    document.documentElement.firstElementChild === document.head
+                  ];
+                })()
+                "#,
+            )
+            .unwrap();
+        assert_eq!(
+            result,
+            serde_json::json!(["Created", "HEAD", "TITLE", "Created", true])
+        );
+
+        let detached = rt
+            .evaluate(
+                r#"
+                (function() {
+                  const doc = document.implementation.createHTMLDocument();
+                  doc.title = "  Detached   title  ";
+                  return [doc.title, doc.querySelector("title").textContent, doc.referrer];
+                })()
+                "#,
+            )
+            .unwrap();
+        assert_eq!(
+            detached,
+            serde_json::json!(["Detached title", "  Detached   title  ", ""])
+        );
+    }
+
+    #[test]
+    fn document_referrer_has_explicit_navigation_state() {
+        let mut rt = setup_runtime("<html><body></body></html>");
+        assert_eq!(rt.evaluate("document.referrer").unwrap(), serde_json::json!(""));
+
+        rt.set_referrer("https://source.example/path?q=1");
+        assert_eq!(
+            rt.evaluate("document.referrer").unwrap(),
+            serde_json::json!("https://source.example/path?q=1")
+        );
     }
 
     #[test]
@@ -6052,7 +6144,7 @@ mod tests {
         let result = rt
             .call_function_on("() => document.title", None, &[], true)
             .await.unwrap();
-        assert_eq!(result.value.unwrap(), serde_json::json!("Test Page"));
+        assert_eq!(result.value.unwrap(), serde_json::json!("Test"));
     }
 
     #[tokio::test(flavor = "current_thread")]