Do not consider edit mode as a history entry

CLAUDE.md

@@ -75,6 +75,14 @@ Prefer separate, human-readable `.html` files over inlined HTML strings in Go. E
 - Do not inline JS in templates or merge unrelated features into one file
 - `ALT+SHIFT` is the modifier for all keyboard shortcuts — do not introduce others
 - Editor toolbar buttons use `data-action` + `data-key`; adding `data-key` auto-registers the shortcut
+- The editor is a *mode* of a page, not a destination. `history-nav.js` turns any
+  same-path `?edit` link (and the editor's CANCEL link back out) into
+  `location.replace`, and SAVE POSTs via fetch and then rewrites the entry with
+  the saved page. Net effect: an edit session never occupies a history entry of
+  its own. Links to a *different* page's editor (new page / new child) still push.
+  The save POST answers `204` + `X-Target` when the request carries
+  `X-Save-Mode: replace`, because the target may hold a `#section` anchor only
+  the server can compute and fetch drops fragments from followed redirects.
 - For mutating modals (anything that POSTs and then navigates), call `closeModal()` and then `postReplace(action, body, target)` from `page/actions.js`. Do NOT use `<form>.submit()`. Two reasons:
   1. The modal must be removed from the DOM before navigation, or the browser's bfcache snapshots it open and back-nav restores the modal.
   2. `postReplace` uses `window.location.replace` so the action + result occupy a single history entry. A naive POST → 303 → GET creates two entries, and back-nav lands on a stale pre-mutation snapshot of the same page.

assets/editor/main.js

@@ -140,7 +140,46 @@
     function syncContent() {
         hidden.value = view.state.doc.toString();
     }
-    form.addEventListener('submit', syncContent);
+
+    // Save POSTs via fetch and then rewrites the *editor's* history entry with
+    // the resulting page, so the edit session and its result share a single
+    // entry (see history-nav.js). A plain form submit would push a second one
+    // and leave the editor sitting in history behind the saved page.
+    //
+    // The server answers 204 + X-Target instead of a 303 because the target may
+    // carry a #section anchor the client cannot compute, and fetch drops the
+    // fragment from a followed redirect.
+    function postSave() {
+        syncContent();
+        var body = new URLSearchParams(new FormData(form)).toString();
+        fetch(form.action, {
+            method: 'POST',
+            headers: {
+                'Content-Type': 'application/x-www-form-urlencoded',
+                'X-Save-Mode': 'replace',
+            },
+            body: body,
+        }).then(function (res) {
+            if (!res.ok) {
+                return res.text().then(function (msg) {
+                    alert(msg || ('Save failed (' + res.status + ')'));
+                });
+            }
+            var target = res.headers.get('X-Target') || form.action;
+            // replaceState + reload rather than location.replace: if target
+            // differs from the current URL only by fragment the browser would
+            // skip the re-fetch and show pre-save content.
+            window.history.replaceState(null, '', target);
+            window.location.reload();
+        }).catch(function () {
+            alert('Network error — the page was not saved');
+        });
+    }
+
+    form.addEventListener('submit', function (e) {
+        e.preventDefault();
+        postSave();
+    });
 
     // --- Actions ---
 

assets/global-shortcuts.js

@@ -4,7 +4,8 @@
         switch (e.key) {
             case 'E':
                 e.preventDefault();
-                window.location.href = window.location.pathname + '?edit';
+                // replace, not assign — same reasoning as history-nav.js.
+                window.location.replace(window.location.pathname + '?edit');
                 break;
             case 'N':
                 e.preventDefault();

assets/history-nav.js

@@ -0,0 +1,33 @@
+// Keeps the page editor out of the browser history.
+//
+// Opening the editor for the page you are already on is a mode switch, not a
+// new destination, so it replaces the current history entry instead of pushing
+// one; CANCEL replaces it right back, and SAVE does the same via postSave in
+// editor/main.js. Without this, page -> edit -> save leaves
+// [prev, page, editor, page'] behind and Back walks through the editor and a
+// stale pre-save snapshot of the page before reaching prev.
+//
+// Links to a *different* page's editor (new page, new child) still push — the
+// page you started from has to stay in history.
+(function () {
+    function isEdit(loc) {
+        return new URLSearchParams(loc.search).has('edit');
+    }
+
+    document.addEventListener('click', function (e) {
+        if (e.defaultPrevented || e.button !== 0) return;
+        if (e.metaKey || e.ctrlKey || e.shiftKey || e.altKey) return;
+        var a = e.target.closest ? e.target.closest('a[href]') : null;
+        if (!a || a.target || a.hasAttribute('download')) return;
+
+        var url = new URL(a.href, window.location.href);
+        if (url.origin !== window.location.origin) return;
+        if (url.pathname !== window.location.pathname) return;
+        // Same page: only editor entry/exit is a mode switch. Plain anchor
+        // links share the pathname too and must keep their normal behaviour.
+        if (!isEdit(url) && !isEdit(window.location)) return;
+
+        e.preventDefault();
+        window.location.replace(url.href);
+    });
+}());

assets/layout.html

@@ -10,6 +10,7 @@
         <link rel="stylesheet" href="/_/style.css" />
         <script src="/_/modal.js"></script>
         <script src="/_/global-shortcuts.js"></script>
+        <script src="/_/history-nav.js"></script>
         <script src="/_/search-suggest.js" defer></script>
         <script src="/_/tree-picker.js"></script>
         <script src="/_/companion.js" defer></script>

main.go

@@ -465,6 +465,15 @@ func (h *handler) handlePost(w http.ResponseWriter, r *http.Request, urlPath, fs
 			}
 		}
 	}
+	// The editor saves via fetch so the save and its result share one history
+	// entry (see assets/history-nav.js). Hand it the target instead of a 303:
+	// the browser would follow the redirect into a second entry, and fetch
+	// drops the #section fragment from a followed redirect anyway.
+	if r.Header.Get("X-Save-Mode") == "replace" {
+		w.Header().Set("X-Target", redirectTarget)
+		w.WriteHeader(http.StatusNoContent)
+		return
+	}
 	http.Redirect(w, r, redirectTarget, http.StatusSeeOther)
 }