diff --git a/crates/automation/tests/it/portfolio_info.rs b/crates/automation/tests/it/portfolio_info.rs
index 8da6310817..750a3e8840 100644
--- a/crates/automation/tests/it/portfolio_info.rs
+++ b/crates/automation/tests/it/portfolio_info.rs
@@ -4,6 +4,7 @@
 use pdfcraft_automation::{Automation, Content};
 use serde_json::{Value, json};
 
+/// Call tool `name` and return its JSON result.
 fn tool(a: &mut Automation, name: &str, args: Value) -> Value {
     match a.call(name, &args).unwrap().remove(0) {
         Content::Json(value) => value,
@@ -34,6 +35,7 @@ trailer << /Root 1 0 R >>
     .into_bytes()
 }
 
+/// `doc_info` names a portfolio's initial document and view, and reports none for a plain file.
 #[test]
 fn doc_info_names_the_document_a_portfolio_presents_first() {
     let dir = tempfile::tempdir().unwrap();
diff --git a/crates/render/src/inspect/core.rs b/crates/render/src/inspect/core.rs
index 4602bc2e6b..fff53dca91 100644
--- a/crates/render/src/inspect/core.rs
+++ b/crates/render/src/inspect/core.rs
@@ -161,6 +161,8 @@ impl<'a> Inspector<'a> {
         me
     }
 
+    /// Read the document's catalog and pages into `info`: metadata, outline, fields, layers,
+    /// fonts, attachments, a portfolio and where it opens.
     pub(super) fn fill(&self, info: &mut DocInfo) {
         // lopdf drops /Encrypt from the trailer once it has decrypted the file.
         info.encrypted = self.doc.encrypted();
@@ -289,6 +291,7 @@ impl<'a> Inspector<'a> {
         Portfolio { initial, view }
     }
 
+    /// The object a reference points at, or `o` itself for a direct object or a broken reference.
     pub(super) fn resolve(&self, o: &'a Object) -> &'a Object {
         self.doc.dereference(o).map(|(_, o)| o).unwrap_or(o)
     }
diff --git a/crates/render/src/inspect/portfolio_tests.rs b/crates/render/src/inspect/portfolio_tests.rs
index 27c085cfae..301a9dab73 100644
--- a/crates/render/src/inspect/portfolio_tests.rs
+++ b/crates/render/src/inspect/portfolio_tests.rs
@@ -26,10 +26,13 @@ trailer << /Root 1 0 R >>
     .into_bytes()
 }
 
+/// The portfolio [`portfolio`] with `collection` reads as.
 fn read(collection: Option<&str>) -> Option<Portfolio> {
     inspect(Arc::new(portfolio(collection)), None).expect("opens").portfolio
 }
 
+/// `/D` picks the attachment presented first, matched as the keys decode, and `/View` how the
+/// list first shows.
 #[test]
 fn a_portfolio_presents_the_attachment_its_d_names() {
     // `/D` names `b.pdf` in the keys' own UTF-16, then as a literal string: both decode as the
diff --git a/crates/ui-egui/src/app/files.rs b/crates/ui-egui/src/app/files.rs
index d5550cdffc..90dbf7025c 100644
--- a/crates/ui-egui/src/app/files.rs
+++ b/crates/ui-egui/src/app/files.rs
@@ -247,6 +247,8 @@ impl PdfCraftApp {
         self.finish_open(name, path, bytes.len(), prepared, activate).map(|_| ())
     }
 
+    /// Admit a prepared document: its tab, the panels and view it opens with, a portfolio's file
+    /// list and initial document, the recent-files entry and what its scripts said on opening.
     fn finish_open(
         &mut self,
         name: &str,
@@ -316,9 +318,9 @@ impl PdfCraftApp {
             if opening_mode != Mode::Read && self.lists_files(id) {
                 self.show_portfolio_files(id, right_before);
             }
-            if let Some(index) = portfolio_initial {
-                self.portfolio_initial = Some((id, index));
-            }
+            // A document opening in front of a portfolio that hasn't presented its initial
+            // document yet (files opened together) keeps the front.
+            self.portfolio_initial = portfolio_initial.map(|index| (id, index));
         }
         if activate
             && self.left_open
@@ -428,7 +430,9 @@ impl PdfCraftApp {
     /// Leaving the tab gives back the panel the list replaced, unless the reader changed panels
     /// meanwhile. Called every frame.
     pub(crate) fn present_portfolios(&mut self) {
-        if let Some((doc, index)) = self.portfolio_initial.take() {
+        if let Some((doc, index)) = self.portfolio_initial.take()
+            && self.active_ids().is_some_and(|(_, id)| id == doc)
+        {
             self.attachment_action(doc, index, true);
             // A portfolio inside the portfolio waits until the reader opens it, so a nested
             // file can't open tab after tab on its own.
diff --git a/crates/ui-egui/src/lib.rs b/crates/ui-egui/src/lib.rs
index ac0f97f7fd..f5a1ed5440 100644
--- a/crates/ui-egui/src/lib.rs
+++ b/crates/ui-egui/src/lib.rs
@@ -269,7 +269,8 @@ pub struct PdfCraftApp {
     /// showing its comments or bookmarks (#1590). Remembered across restarts.
     pub right_panel_closed: bool,
     /// A portfolio that just opened and the attachment it presents first (`/Collection /D`),
-    /// opened by [`Self::present_portfolios`] on the next frame.
+    /// opened by [`Self::present_portfolios`] on the next frame while the portfolio is still the
+    /// active tab.
     portfolio_initial: Option<(DocId, usize)>,
     /// The document whose tab [`Self::present_portfolios`] last saw active.
     portfolio_seen: Option<DocId>,
diff --git a/crates/ui-egui/tests/it/portfolio.rs b/crates/ui-egui/tests/it/portfolio.rs
index 615363bf26..d8dd2726b3 100644
--- a/crates/ui-egui/tests/it/portfolio.rs
+++ b/crates/ui-egui/tests/it/portfolio.rs
@@ -78,6 +78,8 @@ fn select(h: &mut Harness<'static, PdfCraftApp>, index: usize) {
     h.run_steps(2);
 }
 
+/// The initial document opens in front, and the portfolio's tab lists its files whatever the
+/// reader's panel preference, giving the panel back when left.
 #[test]
 fn a_portfolio_opens_its_initial_document_and_shows_its_files_with_the_panel_closed() {
     let mut h = opened(portfolio("/Collection << /D (form.pdf) /View /T >>", &[("intro.pdf", PAGE), ("form.pdf", PAGE)]), true);
@@ -106,6 +108,7 @@ fn a_portfolio_opens_its_initial_document_and_shows_its_files_with_the_panel_clo
     assert_eq!(h.state().right, Some(RightPanel::Bookmarks));
 }
 
+/// The initial document opens on its own panels, not on the portfolio's file list.
 #[test]
 fn the_initial_document_opens_without_the_portfolios_file_list() {
     // The portfolio asks for the Attachments panel too (`/PageMode /UseAttachments`), and the
@@ -118,6 +121,28 @@ fn the_initial_document_opens_without_the_portfolios_file_list() {
     assert_eq!(h.state().right, Some(RightPanel::Attachments));
 }
 
+/// A file opened together with a portfolio, after it, stays in front.
+#[test]
+fn a_file_opened_after_the_portfolio_keeps_the_front() {
+    // Two files opened at once, the portfolio first: the second stays in front, and the
+    // portfolio's initial document waits for the reader, whose list shows on the portfolio's tab.
+    let pdf = portfolio("/Collection << /D (form.pdf) >>", &[("form.pdf", PAGE)]);
+    let mut h = Harness::builder().with_size(egui::vec2(1400.0, 900.0)).build_eframe(move |_cc| {
+        let mut app = PdfCraftApp::new();
+        app.set_option("language", "en").unwrap();
+        app.right_panel_closed = true;
+        app.open_bytes("portfolio.pdf", None, pdf.clone()).unwrap();
+        app.open_bytes("other.pdf", None, PAGE.to_vec()).unwrap();
+        app
+    });
+    h.run_steps(4);
+    assert_eq!(tabs(&h), (vec!["portfolio.pdf".into(), "other.pdf".into()], Some("other.pdf".into())));
+    assert_eq!(h.state().right, None);
+    select(&mut h, 0);
+    assert_eq!(h.state().right, Some(RightPanel::Attachments));
+}
+
+/// `/View /H` presents the initial document but leaves the file list to the reader.
 #[test]
 fn a_portfolio_that_keeps_its_list_hidden_still_presents_its_initial_document() {
     let mut h = opened(portfolio("/Collection << /D (form.pdf) /View /H >>", &[("intro.pdf", PAGE), ("form.pdf", PAGE)]), true);
@@ -126,6 +151,7 @@ fn a_portfolio_that_keeps_its_list_hidden_still_presents_its_initial_document()
     assert_eq!(h.state().right, None, "/View /H: the list shows when the reader asks for it");
 }
 
+/// Without a PDF to present, the portfolio stays in front with its files listed.
 #[test]
 fn a_portfolio_without_an_initial_document_shows_its_files_over_the_cover() {
     // Without `/D` the cover is the initial document; a `/D` naming a file that isn't a PDF
@@ -137,6 +163,7 @@ fn a_portfolio_without_an_initial_document_shows_its_files_over_the_cover() {
     }
 }
 
+/// A portfolio nested in the initial document doesn't open a chain of tabs.
 #[test]
 fn a_portfolio_inside_the_initial_document_waits_for_the_reader() {
     // The initial document is itself a portfolio presenting a third file: opening the outer