feat(post-form): text-only draft persistence (U6)

Mirror text field values (incl. EasyMDE content) to localStorage on every
edit and restore them on load. Clear the draft only when the server confirms
a successful post (.notices.success) — the invariant that guarantees text
survives validation failures, save errors, and session expiry (login form
shown → form absent → draft left intact for post-reauth restore). Photos are
not persisted (File/Blob can't serialize); on restore an inline hint says
they need re-selecting.

Refs R19 (preserve-on-failure), R20, KTD6.

themes/intotheeast/js/src/post-form.js

@@ -401,11 +401,97 @@ function initValidation() {
     });
 }
 
+/* ── Draft persistence (U6, R19 preserve-on-failure + R20, KTD6) ──
+ * Text field values are mirrored to localStorage so a failed submit or an
+ * expired session mid-compose never loses the writing. Photos can't be
+ * serialized (File/Blob) so they are NOT persisted — an inline hint says so
+ * on restore. The draft is cleared ONLY when the server confirms a successful
+ * post (<div class="notices success">), which is exactly what guarantees the
+ * text survives every non-success outcome, independent of failure-type sniffing.
+ */
+var DRAFT_KEY = 'intotheeast:new-entry-draft';
+
+function draftEls(form) {
+    return Array.prototype.slice.call(form.querySelectorAll('[name^="data["]'))
+        .filter(function (el) {
+            if (el.type === 'file') return false;
+            var n = el.name;
+            return n.indexOf('data[_json') !== 0 && n.indexOf('data[photos') !== 0;
+        });
+}
+
+function showReauthHint() {
+    var picker = document.querySelector('.photo-picker');
+    if (!picker || picker.querySelector('.photo-picker__reauth-hint')) return;
+    var p = document.createElement('p');
+    p.className = 'photo-picker__reauth-hint is-shown';
+    p.textContent = 'Your text was restored — photos need re-selecting (they can’t be saved in a draft).';
+    picker.appendChild(p);
+}
+
+function initDraft() {
+    var form = document.querySelector('form[name="new-entry"]');
+    if (!form) return; // e.g. session expired → login form shown; draft is left intact
+
+    // A confirmed successful post: clear the draft and do NOT restore onto the
+    // freshly reset form. This runs before any save, so process.reset can't
+    // round-trip blank fields back into storage.
+    if (document.querySelector('.notices.success')) {
+        try { localStorage.removeItem(DRAFT_KEY); } catch (e) { /* ignore */ }
+        return;
+    }
+
+    function save() {
+        var data = {};
+        draftEls(form).forEach(function (el) {
+            if (el.type === 'radio') { if (el.checked) { data[el.name] = el.value; } }
+            else { data[el.name] = el.value; }
+        });
+        try { localStorage.setItem(DRAFT_KEY, JSON.stringify(data)); } catch (e) { /* quota / private mode */ }
+    }
+
+    var raw = null;
+    try { raw = localStorage.getItem(DRAFT_KEY); } catch (e) { raw = null; }
+    if (raw) {
+        var data = null;
+        try { data = JSON.parse(raw); } catch (e) { data = null; }
+        if (data) {
+            var restoredSomething = false;
+            Object.keys(data).forEach(function (name) {
+                var val = data[name];
+                if (val != null && String(val).trim()) { restoredSomething = true; }
+                if (name === 'data[content]') { return; } // restored via the editor below
+                var radios = form.querySelectorAll('input[type="radio"][name="' + name + '"]');
+                if (radios.length) {
+                    radios.forEach(function (r) { r.checked = (r.value === val); });
+                    return;
+                }
+                var el = form.querySelector('[name="' + name + '"]');
+                if (el && el.type !== 'file') { el.value = val; }
+            });
+            if (window.postFormEditor && data['data[content]'] != null) {
+                window.postFormEditor.value(data['data[content]']);
+            }
+            if (restoredSomething) { showReauthHint(); }
+        }
+    }
+
+    // Save text on every edit (change covers selects/toggles; input covers text).
+    form.addEventListener('input', save);
+    form.addEventListener('change', save);
+    if (window.postFormEditor) {
+        window.postFormEditor.codemirror.on('change', save);
+    }
+}
+
 /* ── Boot ────────────────────────────────────────────────── */
 function boot() {
-    // Exposed for later units (U6 draft restore) and the Playwright specs;
+    // Exposed for U6 draft restore and the Playwright specs; null when this
-    // null when this bundle loads on a page without the content field.
+    // bundle loads on a page without the content field.
     window.postFormEditor = initEditor();
+    // Restore before disclosure/geo so their on-load checks (auto-open,
+    // weather-button enable) see the restored values.
+    initDraft();
     initPhotoPicker();
     initDisclosure();
     initGeo();