diff --git a/CLAUDE.md b/CLAUDE.md
index 60df8b4..124d2e4 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -242,6 +242,40 @@ curl -s "https://git.unturf.com/api/v4/projects/engineering%2Fremarkbox%2Fremark
 
 The pipeline status will show `"status":"success"` when deployment is complete.
 
+## Capability-Driven Presentation
+
+Follow Russell Ballestrini's capability-driven presentation practice
+(russell.ballestrini.net/capability-driven-presentation/). A page need not look
+identical across all browsers. Accommodate what the user's browser can do:
+
+1. **Single canonical URI** — one URL serves the content.
+2. **Consistent content** — regardless of viewer capabilities.
+3. **Graceful enhancement/degradation** — use available capabilities to enhance presentation.
+
+### The `js-only` / `<noscript>` pattern
+
+Already implemented in `base.j2`:
+
+```html
+<noscript>
+  <style>.js-only {display: none;}</style>
+</noscript>
+```
+
+Apply the `js-only` class to any element that requires JavaScript to function
+(preview panels, AJAX submit buttons, typeahead UIs). When JS is unavailable,
+these elements hide automatically — the user never sees a broken control.
+
+### AJAX form submission
+
+Comment reply forms use progressive enhancement: the form works as a normal
+POST + redirect without JS. When JS is available, `initAjaxCommentForms()` in
+`custom.js` intercepts the submit, sends via `fetch()` with
+`X-Requested-With: XMLHttpRequest`, and inserts the new comment into the DOM
+without a page reload. The server returns JSON (HTTP 201) for AJAX requests
+from verified/anonymous users, and falls back to the normal redirect flow for
+unverified users or on any error.
+
 ## Style
 
 - **Never use "AI" — always say "machine learning."** We grow machine learning, not "AI." This term is forbidden in all permacomputer discourse, marketing, & documentation.
diff --git a/remarkbox/static/js/custom.js b/remarkbox/static/js/custom.js
index 4513446..ba7573e 100644
--- a/remarkbox/static/js/custom.js
+++ b/remarkbox/static/js/custom.js
@@ -212,6 +212,110 @@ function escapeHtml(text) {
     return div.innerHTML;
 }
 
+// AJAX comment submission — capability-driven presentation.
+// When JS is available, intercepts reply form POSTs and submits
+// via fetch so the page does not reload. When JS is disabled,
+// the form falls back to the normal POST + redirect.
+function initAjaxCommentForms() {
+    document.querySelectorAll('form[action*="/reply"]').forEach(function(form) {
+        // Skip forms that are already wired up.
+        if (form.dataset.ajaxBound) return;
+        form.dataset.ajaxBound = '1';
+
+        form.addEventListener('submit', function(e) {
+            var submitBtn = form.querySelector('.rb-submit');
+            if (!submitBtn) return; // let normal submit proceed
+
+            e.preventDefault();
+            var formData = new FormData(form);
+            var originalLabel = submitBtn.value;
+            submitBtn.disabled = true;
+            submitBtn.value = 'Sending...';
+
+            fetch(form.action, {
+                method: 'POST',
+                body: formData,
+                headers: { 'X-Requested-With': 'XMLHttpRequest' }
+            })
+            .then(function(response) {
+                if (!response.ok || response.status !== 201) {
+                    // Auth redirect, validation error, or server error
+                    // — fall back to regular form submit.
+                    submitBtn.disabled = false;
+                    submitBtn.value = originalLabel;
+                    form.submit();
+                    return;
+                }
+                return response.json();
+            })
+            .then(function(data) {
+                if (!data) return;
+                insertReply(data, form);
+                // Clear the textarea.
+                var textarea = form.querySelector('.common-textarea');
+                if (textarea) textarea.value = '';
+                // Clear the preview.
+                var preview = form.querySelector('.preview');
+                if (preview) preview.innerHTML = '';
+                submitBtn.disabled = false;
+                submitBtn.value = originalLabel;
+            })
+            .catch(function() {
+                // Network error — fall back to regular form submit.
+                submitBtn.disabled = false;
+                submitBtn.value = originalLabel;
+                form.submit();
+            });
+        });
+    });
+}
+
+function insertReply(data, form) {
+    // Build a new node div matching the existing markup structure.
+    var nodeDiv = document.createElement('div');
+    nodeDiv.id = 'node-' + data.id;
+    nodeDiv.className = 'node';
+
+    var authorSpan = '<span class="author-and-date">'
+        + '<strong>' + escapeHtml(data.author_name) + '</strong> '
+        + '<span class="date">' + escapeHtml(data.ago_string) + '</span>'
+        + '</span>';
+
+    var contentDiv = '<div id="node-data-' + data.id + '" class="node-data">'
+        + data.data_html + '</div>';
+
+    var statusHtml = '';
+    if (!data.approved) {
+        statusHtml = '<span>(hidden: waiting for approval)</span>';
+    }
+
+    nodeDiv.innerHTML = authorSpan + statusHtml + contentDiv;
+
+    // Insert after the reply form's parent container.
+    var parentNode = form.closest('.node, .remark-box-div-main');
+    if (parentNode) {
+        // Find or create a children container.
+        var childrenContainer = parentNode.querySelector('[id^="node-children-"]');
+        if (childrenContainer) {
+            childrenContainer.insertBefore(nodeDiv, childrenContainer.firstChild);
+        } else {
+            parentNode.appendChild(nodeDiv);
+        }
+    }
+
+    // Add anchor for the new comment.
+    var anchor = document.createElement('a');
+    anchor.className = 'anchor';
+    anchor.id = data.id;
+    nodeDiv.parentNode.insertBefore(anchor, nodeDiv);
+
+    nodeDiv.scrollIntoView({ behavior: 'smooth', block: 'center' });
+
+    // Briefly highlight the new comment.
+    nodeDiv.classList.add('focused');
+    setTimeout(function() { nodeDiv.classList.remove('focused'); }, 3000);
+}
+
 // Initialize on DOM ready
 document.addEventListener('DOMContentLoaded', function() {
 
@@ -229,6 +333,9 @@ document.addEventListener('DOMContentLoaded', function() {
         });
     });
 
+    // Initialize AJAX comment forms (capability-driven presentation).
+    initAjaxCommentForms();
+
     // Vote button handlers
     document.querySelectorAll('button.vote-up').forEach(function(btn) {
         btn.addEventListener('click', function() {
diff --git a/remarkbox/views/reply_node.py b/remarkbox/views/reply_node.py
index 6e7f298..31a167d 100644
--- a/remarkbox/views/reply_node.py
+++ b/remarkbox/views/reply_node.py
@@ -4,6 +4,8 @@ from pyramid.csrf import check_csrf_token
 
 from pyramid.httpexceptions import HTTPFound
 
+from pyramid.response import Response
+
 from . import (
     get_referer_or_home,
     get_embed_route_uri,
@@ -137,6 +139,28 @@ def reply_node(request):
     msg = ("Your post was successful!", "success")
     request.session.flash(msg)
 
+    # AJAX request — return JSON instead of redirect (capability-driven presentation).
+    is_ajax = request.headers.get("X-Requested-With") == "XMLHttpRequest"
+    if is_ajax and (user_surrogate or child.verified):
+        author_name = ""
+        if child.user:
+            author_name = child.user.name or ""
+        elif child.user_surrogate:
+            author_name = child.user_surrogate.name or "Anonymous"
+        return Response(
+            json={
+                "id": str(child.id),
+                "parent_id": str(child.parent_id) if child.parent_id else None,
+                "data_html": child.data_html,
+                "author_name": author_name,
+                "ago_string": child.human_created_timestamp,
+                "approved": child.approved,
+                "depth": child.graph_depth,
+                "verified": child.verified,
+            },
+            status_code=201,
+        )
+
     # set return_to URI.
     if request.mode == "embed":
         return_to = get_embed_route_uri(request, child.root.uri.data, child.id)