diff --git a/private/attachment-references.rkt b/private/attachment-references.rkt
index 27e4e3c..27d61d0 100644
--- a/private/attachment-references.rkt
+++ b/private/attachment-references.rkt
@@ -5,6 +5,7 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (require db
+         net/uri-codec
          racket/string)
 
 (provide replace-current-attachment-references!
@@ -27,6 +28,12 @@ SQL
 (define (attachment-url reference stored-name)
   (format "/uploads/~a/~a" reference stored-name))
 
+(define (attachment-url-variants reference stored-name)
+  (list (attachment-url reference stored-name)
+        (format "/uploads/~a/~a"
+                reference
+                (uri-path-segment-unreserved-encode stored-name))))
+
 (define (page-references db page-id)
   (let* ((current
           (query-row db
@@ -57,7 +64,8 @@ SQL
           (stored-name (vector-ref row 2))
           (found? #f))
       (for ((reference (in-list (page-references db owner-page-id))))
-        (when (string-contains? markdown (attachment-url reference stored-name))
+        (when (for/or ((url (in-list (attachment-url-variants reference stored-name))))
+                (string-contains? markdown url))
           (set! found? #t)))
       (when found?
         (query-exec db
@@ -89,6 +97,21 @@ SQL
   (record-references! db page-id sql-null markdown #t referenced-at)
   (void))
 
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Tests for module attachment-references.rkt.
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+(module+ test
+  (require rackunit)
+
+  (define urls
+    (attachment-url-variants
+     "review-zuidas-2026:appreciatie"
+     "1788796826-35348-Review ZuidasDok.docx"))
+  (check-equal?
+   urls
+   (list "/uploads/review-zuidas-2026:appreciatie/1788796826-35348-Review ZuidasDok.docx"
+         "/uploads/review-zuidas-2026:appreciatie/1788796826-35348-Review%20ZuidasDok.docx")))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; goal   : Record attachment references present in an immutable page version.
 ; pre    : page-version-id identifies the stored version represented by markdown.
diff --git a/static/css/wiki.css b/static/css/wiki.css
index b0c63f5..5b388fe 100644
--- a/static/css/wiki.css
+++ b/static/css/wiki.css
@@ -122,6 +122,10 @@ button { cursor: pointer; }
   text-decoration: line-through;
 }
 
+.EasyMDEContainer .editor-toolbar button.rw-mde-save {
+  display: none;
+}
+
 .EasyMDEContainer .CodeMirror,
 .EasyMDEContainer .CodeMirror-scroll,
 .EasyMDEContainer .editor-preview-side {
@@ -222,6 +226,62 @@ body {
   padding: 18px 16px 28px;
 }
 
+.sidebar-toggle {
+  display: grid;
+  width: 34px;
+  height: 34px;
+  margin: -8px -8px 8px auto;
+  place-items: center;
+  border: 1px solid transparent;
+  border-radius: 3px;
+  background: transparent;
+  color: var(--wiki-link);
+}
+
+.sidebar-toggle:hover,
+.sidebar-toggle:focus-visible {
+  background: #fff;
+  border-color: var(--wiki-border);
+  outline: 0;
+}
+
+.sidebar-toggle svg {
+  width: 18px;
+  height: 18px;
+  stroke-width: 1.8;
+}
+
+body.sidebar-collapsed #app {
+  grid-template-columns: 52px minmax(0, 1fr);
+}
+
+body.sidebar-collapsed #sidebar {
+  padding: 12px 8px;
+  overflow: hidden;
+}
+
+body.sidebar-collapsed #sidebar > :not(#sidebar-toggle):not(.sidebar-icon-nav) {
+  display: none;
+}
+
+body.sidebar-collapsed #sidebar .sidebar-toggle {
+  margin: 0 auto;
+}
+
+body.sidebar-collapsed #sidebar .sidebar-icon-nav {
+  flex-direction: column;
+  margin: 14px 0 0;
+}
+
+body.sidebar-collapsed #sidebar .sidebar-icon-link {
+  width: 36px;
+}
+
+body.sidebar-collapsed #sidebar .sidebar-icon-link + .sidebar-icon-link {
+  border-top: 1px solid #c8cbd0;
+  border-left: 0;
+}
+
 .brand {
   display: block;
   color: #111;
@@ -909,6 +969,10 @@ body.editor-mode .EasyMDEContainer .editor-toolbar.fullscreen {
   background: white;
 }
 
+body.editor-mode .EasyMDEContainer .editor-toolbar.fullscreen button.rw-mde-save {
+  display: inline-block;
+}
+
 body.editor-mode .EasyMDEContainer .editor-statusbar.fullscreen {
   bottom: 0;
   min-height: 28px;
@@ -972,6 +1036,14 @@ body.editor-mode .EasyMDEContainer .editor-preview-side {
   border-top: 0;
 }
 
+body.editor-mode .editor-shell .EasyMDEContainer:not(:has(.editor-preview-active-side)) {
+  grid-template-columns: minmax(0, 1fr);
+}
+
+body.editor-mode .editor-shell .EasyMDEContainer:not(:has(.editor-preview-active-side)) .CodeMirror {
+  grid-column: 1;
+}
+
 body.editor-mode .EasyMDEContainer .CodeMirror-sided {
   width: 100% !important;
 }
diff --git a/static/index.html b/static/index.html
index 124d4f5..7abbb04 100644
--- a/static/index.html
+++ b/static/index.html
@@ -14,6 +14,9 @@
   <div id="connection-status" class="connection-status hidden" role="status"></div>
   <div id="app">
     <aside id="sidebar">
+      <button id="sidebar-toggle" class="sidebar-toggle" type="button" title="Collapse sidebar" data-tr-title="collapse-sidebar" aria-label="Collapse sidebar" data-tr-aria-label="collapse-sidebar" aria-controls="sidebar" aria-expanded="true">
+        <i data-lucide="panel-left-close" aria-hidden="true"></i>
+      </button>
       <a id="wiki-brand" class="brand" href="#">Racket Wiki</a>
       <nav class="sidebar-icon-nav" aria-label="Wiki navigation">
         <a id="bookmarks-link" class="sidebar-icon-link" href="#bookmarks" title="Bookmarks" data-tr-title="bookmarks" aria-label="Bookmarks" data-tr-aria-label="bookmarks"><i data-lucide="star"></i><span class="visually-hidden" data-tr="bookmarks">Bookmarks</span></a>
diff --git a/static/js/wiki.js b/static/js/wiki.js
index 8eb9d92..427f2a1 100644
--- a/static/js/wiki.js
+++ b/static/js/wiki.js
@@ -13,6 +13,7 @@ import {
   expandNamespacedMarkdownLinks,
   expandTodoMarkup,
   expandWikiMentions,
+  normalizeMarkdownLinkDestinations,
   protectCamelCaseWikiWords,
   extractCmapEmbeds,
   restoreCmapEmbeds
@@ -70,6 +71,8 @@ import { ComboBox } from "./widgets/combobox.js";
 
   let easyMDE = null;
   let pendingWikiCmapLinkLabel = "";
+  const sidebarPreferenceKey = "racket-wiki-sidebar-collapsed";
+  const editorSideBySidePreferenceKey = "racket-wiki-editor-side-by-side";
 
   ////////////////////////////////////////////////////////////////////////////////
   // General UI and HTTP support
@@ -133,6 +136,50 @@ import { ComboBox } from "./widgets/combobox.js";
     document.documentElement.lang = state.language || "en";
   }
 
+  function setSidebarCollapsed(collapsed, remember = true) {
+    document.body.classList.toggle("sidebar-collapsed", collapsed);
+    const toggle = $("sidebar-toggle");
+    if (!toggle) return;
+    const translationKey = collapsed ? "expand-sidebar" : "collapse-sidebar";
+    toggle.dataset.trTitle = translationKey;
+    toggle.dataset.trAriaLabel = translationKey;
+    toggle.title = tr(translationKey, collapsed ? "Expand sidebar" : "Collapse sidebar");
+    toggle.setAttribute("aria-label", toggle.title);
+    toggle.setAttribute("aria-expanded", String(!collapsed));
+    const icon = document.createElement("i");
+    icon.dataset.lucide = collapsed ? "panel-left-open" : "panel-left-close";
+    icon.setAttribute("aria-hidden", "true");
+    const oldIcon = toggle.querySelector("[data-lucide], svg");
+    if (oldIcon) {
+      oldIcon.replaceWith(icon);
+    } else {
+      toggle.append(icon);
+    }
+    if (window.lucide && typeof window.lucide.createIcons === "function") {
+      window.lucide.createIcons();
+    }
+    if (remember) {
+      try {
+        window.sessionStorage.setItem(sidebarPreferenceKey, collapsed ? "true" : "false");
+      } catch (_error) {
+        // A blocked session storage should not prevent the toggle from working.
+      }
+    }
+  }
+
+  function initializeSidebarToggle() {
+    const toggle = $("sidebar-toggle");
+    if (!toggle) return;
+    let collapsed = false;
+    try {
+      collapsed = window.sessionStorage.getItem(sidebarPreferenceKey) === "true";
+    } catch (_error) {
+      collapsed = false;
+    }
+    setSidebarCollapsed(collapsed, false);
+    toggle.addEventListener("click", () => setSidebarCollapsed(!document.body.classList.contains("sidebar-collapsed")));
+  }
+
   function navigateToHash(targetHash) {
     const navigate = () => {
       if (location.hash === targetHash) return route();
@@ -204,7 +251,8 @@ import { ComboBox } from "./widgets/combobox.js";
 
   function renderMarkdown(markdown, pageSlug = null) {
     const extracted = extractCmapEmbeds(markdown || "");
-    const withExplicitWikiLinks = expandNamespacedMarkdownLinks(extracted.markdown);
+    const normalizedLinks = normalizeMarkdownLinkDestinations(extracted.markdown);
+    const withExplicitWikiLinks = expandNamespacedMarkdownLinks(normalizedLinks);
     const withWikiLinks = expandWikiMentions(
       withExplicitWikiLinks,
       state.pages,
@@ -436,6 +484,32 @@ import { ComboBox } from "./widgets/combobox.js";
     easyMDE.codemirror.refresh();
   }
 
+  function preferredEditorSideBySide() {
+    try {
+      const stored = window.sessionStorage.getItem(editorSideBySidePreferenceKey);
+      return stored === null ? true : stored === "true";
+    } catch (_error) {
+      return true;
+    }
+  }
+
+  function rememberEditorSideBySide() {
+    if (!easyMDE) return;
+    try {
+      window.sessionStorage.setItem(
+        editorSideBySidePreferenceKey,
+        String(easyMDE.isSideBySideActive())
+      );
+    } catch (_error) {
+      // A blocked session storage should not prevent the editor from working.
+    }
+  }
+
+  function toggleEditorSideBySide() {
+    easyMDE.toggleSideBySide();
+    rememberEditorSideBySide();
+  }
+
   function protectCamelCaseInPage() {
     if (!easyMDE) return;
     const source = easyMDE.value();
@@ -523,9 +597,10 @@ import { ComboBox } from "./widgets/combobox.js";
         "|",
         toolbarButton("undo", EasyMDE.undo, "undo-2", tr("undo", "Undo")),
         toolbarButton("redo", EasyMDE.redo, "redo-2", tr("redo", "Redo")),
+        toolbarButton("save", savePageFromFullscreen, "save", tr("save", "Save"), { noDisable: true }),
         toolbarButton("raw-markdown", toggleRawMarkdown, "file-text", tr("raw-markdown", "Raw Markdown"), { noDisable: true }),
         toolbarButton("preview", EasyMDE.togglePreview, "eye", tr("preview", "Preview"), { noDisable: true }),
-        toolbarButton("side-by-side", EasyMDE.toggleSideBySide, "columns-2", tr("side-by-side", "Side by side"), { noDisable: true, noMobile: true }),
+        toolbarButton("side-by-side", toggleEditorSideBySide, "columns-2", tr("side-by-side", "Side by side"), { noDisable: true, noMobile: true }),
         toolbarButton("fullscreen", EasyMDE.toggleFullScreen, "maximize", tr("fullscreen", "Fullscreen"), { noDisable: true, noMobile: true })
       ]
     });
@@ -575,7 +650,7 @@ import { ComboBox } from "./widgets/combobox.js";
     requestAnimationFrame(() => {
       easyMDE.codemirror.refresh();
       const wideScreen = window.matchMedia("(min-width: 901px)").matches;
-      if (wideScreen && !easyMDE.isSideBySideActive()) {
+      if (wideScreen && easyMDE.isSideBySideActive() !== preferredEditorSideBySide()) {
         easyMDE.toggleSideBySide();
       }
       updateEditorChromeMetrics();
@@ -1045,6 +1120,17 @@ import { ComboBox } from "./widgets/combobox.js";
    * post   : A successful save refreshes page metadata and opens the stored page.
    */
   async function savePage() {
+    return savePageWithOptions();
+  }
+
+  function savePageFromFullscreen() {
+    savePageWithOptions({ keepEditing: true }).catch((error) => {
+      $("save-status").textContent = error.message;
+    });
+  }
+
+  /** Save the current Markdown and optionally keep the editor active. */
+  async function savePageWithOptions({ keepEditing = false } = {}) {
     const title = $("editor-title").value.trim();
     const namespace = $("editor-namespace").value.trim();
     const currentSlug = state.editingNew ? state.newPageSlug : state.currentPage?.slug;
@@ -1096,8 +1182,14 @@ import { ComboBox } from "./widgets/combobox.js";
         applyTranslations();
         $("account-role").textContent = tr(`role-${state.session.user.role}`, state.session.user.role);
       }
-      location.hash = `#/${encodeURIComponent(page.slug)}`;
-      await openPage(page.slug);
+      if (keepEditing) {
+        $("editor-namespace").disabled = true;
+        updateEditorSlugInfo();
+        $("edit-summary").value = "";
+      } else {
+        location.hash = `#/${encodeURIComponent(page.slug)}`;
+        await openPage(page.slug);
+      }
       $("save-status").textContent = tr("saved", "Saved");
     } catch (error) {
       $("save-status").textContent = error.message;
@@ -1189,7 +1281,7 @@ import { ComboBox } from "./widgets/combobox.js";
     }
     const result = await uploadOneFile(file);
     $("save-status").textContent = tr("image-upload-complete", "Image upload complete");
-    return result.url;
+    return encodeURI(result.url);
   }
 
   /**
@@ -1206,9 +1298,10 @@ import { ComboBox } from "./widgets/combobox.js";
       for (const file of fileList) {
         const result = await uploadOneFile(file);
         const escapedName = file.name.replace(/[\[\]]/g, "\\$&");
+        const url = encodeURI(result.url);
         const markdown = isInlineImage(file)
-          ? `![${escapedName}](${result.url})`
-          : `[${escapedName}](${result.url})`;
+          ? `![${escapedName}](${url})`
+          : `[${escapedName}](${url})`;
         insertTextAtCursor(`\n${markdown}\n`);
       }
       $("save-status").textContent = tr("upload-complete", "Upload complete");
@@ -2023,6 +2116,7 @@ import { ComboBox } from "./widgets/combobox.js";
     state.translationTemplate = translationData.template || "";
     state.translations = translationData.translations || {};
     applyTranslations();
+    initializeSidebarToggle();
     await cmapWorkspace.initialize();
     initializeEditor();
     $("account-name").textContent = state.session.user.displayName;
diff --git a/static/js/wiki/markdown.js b/static/js/wiki/markdown.js
index bbfb756..05e6d9a 100644
--- a/static/js/wiki/markdown.js
+++ b/static/js/wiki/markdown.js
@@ -182,6 +182,44 @@ function positionIsProtected(start, end, ranges) {
   return false;
 }
 
+/** Normalize link destinations that contain whitespace before Marked parses them. */
+function normalizeMarkdownLinkDestinations(markdown) {
+  const lines = String(markdown || "").split("\n");
+  const result = [];
+  let fence = null;
+  const linkPattern = /(!?\[[^\]\n]*\]\()([^\)\n]*)(\))/g;
+
+  for (const line of lines) {
+    const fenceMatch = line.match(/^\s*(```+|~~~+)/);
+    if (fenceMatch) {
+      const marker = fenceMatch[1].charAt(0);
+      fence = fence === null ? marker : (fence === marker ? null : fence);
+      result.push(line);
+      continue;
+    }
+    if (fence !== null || /^\s{4}/.test(line)) {
+      result.push(line);
+      continue;
+    }
+
+    const codeRanges = [];
+    for (const match of line.matchAll(/`+[^`\n]*`+/g)) {
+      codeRanges.push({ start: match.index, end: match.index + match[0].length });
+    }
+    result.push(line.replace(linkPattern, (match, before, body, after, offset) => {
+      if (positionIsProtected(offset, offset + match.length, codeRanges)) return match;
+      const trimmed = body.trim();
+      if (!trimmed || trimmed.startsWith("<") || !/\s/.test(trimmed)) return match;
+
+      const titleMatch = trimmed.match(/^(.+?)(\s+(?:"[^"\n]*"|'[^'\n]*'|\([^\)\n]*\)))$/);
+      const destination = titleMatch ? titleMatch[1] : trimmed;
+      const title = titleMatch ? titleMatch[2] : "";
+      return `${before}${encodeURI(destination)}${title}${after}`;
+    }));
+  }
+  return result.join("\n");
+}
+
 /** Prefix every unprotected CamelCase WikiWord with the literal escape marker. */
 function protectCamelCaseWikiWords(markdown) {
   const wikiWordPattern = /(?<![!\p{L}\p{N}._-])((?:\p{Lu}\p{Ll}+){2,})(?![\p{L}\p{N}_-])/gu;
@@ -363,6 +401,7 @@ export {
   expandNamespacedMarkdownLinks,
   expandTodoMarkup,
   expandWikiMentions,
+  normalizeMarkdownLinkDestinations,
   protectCamelCaseWikiWords,
   extractCmapEmbeds,
   restoreCmapEmbeds
diff --git a/test/wiki-markdown.test.mjs b/test/wiki-markdown.test.mjs
index b742358..474c0a9 100644
--- a/test/wiki-markdown.test.mjs
+++ b/test/wiki-markdown.test.mjs
@@ -9,6 +9,7 @@ import {
   expandTodoMarkup,
   expandWikiMentions,
   extractCmapEmbeds,
+  normalizeMarkdownLinkDestinations,
   protectCamelCaseWikiWords,
   restoreCmapEmbeds
 } from "../static/js/wiki/markdown.js";
@@ -39,6 +40,13 @@ test("explicit namespaced links become internal routes outside code", () => {
     "[Page](#/notes%3Aroadmap)\n[CMap](#cmap/architecture)\n```\n[Code](notes:keep)\n```");
 });
 
+test("link destinations with spaces are encoded without changing code", () => {
+  const markdown = "* [DOC](/uploads/review-zuidas-2026:appreciatie/1788796826-35348-Review ZuidasDok - Hans Dijkema - Beschouwing v3.docx)\n`[code](/uploads/page/file name.txt)`\n```\n[code](/uploads/page/file name.txt)\n```";
+  assert.equal(
+    normalizeMarkdownLinkDestinations(markdown),
+    "* [DOC](/uploads/review-zuidas-2026:appreciatie/1788796826-35348-Review%20ZuidasDok%20-%20Hans%20Dijkema%20-%20Beschouwing%20v3.docx)\n`[code](/uploads/page/file name.txt)`\n```\n[code](/uploads/page/file name.txt)\n```");
+});
+
 test("WikiWords use page and CMap catalogues without expanding protected text", () => {
   const pages = [
     { slug: "homeopathie", namespace: "", pageSlug: "homeopathie", title: "Homeopathie Wiki" }
diff --git a/translate.rkt b/translate.rkt
index 402872d..46bacc8 100644
--- a/translate.rkt
+++ b/translate.rkt
@@ -144,7 +144,7 @@
    'bulleted-list "Bulleted list" 'numbered-list "Numbered list" 'checklist "Checklist" 'code-block "Code block"
    'table "Table" 'link "Link" 'horizontal-rule "Horizontal rule" 'undo "Undo" 'redo "Redo"
    'preview "Preview" 'side-by-side "Side by side" 'fullscreen "Fullscreen" 'raw-markdown "Raw Markdown" 'automatic-wiki-link "Automatic wiki link"
-   'language "Language" 'language-en "English" 'language-nl "Dutch"
+  'language "Language" 'language-en "English" 'language-nl "Dutch" 'collapse-sidebar "Collapse sidebar" 'expand-sidebar "Expand sidebar"
    'no-headings "No headings" 'uploading "Uploading" 'image-upload-complete "Image upload complete" 'upload-complete "Upload complete"
    'by "by" 'result "result" 'results "results" 'for "for" 'page-does-not-exist "The page does not exist."))
 
@@ -270,7 +270,7 @@
    'bulleted-list "Opsomming" 'numbered-list "Genummerde lijst" 'checklist "Checklist" 'code-block "Codeblok"
    'table "Tabel" 'link "Link" 'horizontal-rule "Horizontale lijn" 'undo "Ongedaan maken" 'redo "Opnieuw uitvoeren"
    'preview "Voorbeeld" 'side-by-side "Naast elkaar" 'fullscreen "Volledig scherm" 'raw-markdown "Ruwe Markdown" 'automatic-wiki-link "Automatische wikilink"
-   'language "Taal" 'language-en "Engels" 'language-nl "Nederlands"
+  'language "Taal" 'language-en "Engels" 'language-nl "Nederlands" 'collapse-sidebar "Zijpaneel inklappen" 'expand-sidebar "Zijpaneel uitklappen"
    'no-headings "Geen koppen" 'uploading "Uploaden" 'image-upload-complete "Afbeelding geüpload" 'upload-complete "Upload voltooid"
    'by "door" 'result "resultaat" 'results "resultaten" 'for "voor" 'page-does-not-exist "De pagina bestaat niet."))