diff --git a/TODO.md b/TODO.md
index 6e47ecb..02ee247 100644
--- a/TODO.md
+++ b/TODO.md
@@ -11,6 +11,8 @@ Pending tasks have been split into topic files under [`todo/`](todo/README.md):
 
 ## Recently completed (this session)
 
+- [x] WCAG 3.3.1 `autofocus` on first invalid field — `App::flashAutofocus()` / `consumeAutofocus()` added; `actions/formulaire.php` maps exception messages → field names and stores the autofocus hint in `$_SESSION['_flash_autofocus']`; `actions/edit.php` does the same; `add.php` consumes it via a `withAutofocus()` helper and injects `autofocus => true` into `$attrs` for `text-field.php` / `select-field.php` includes; `edit.php` uses inline ternary for the same; `text-field.php` and `select-field.php` partials now support boolean `true` values in `$attrs` (emit bare attribute names for `autofocus`, `required`, etc.)
+
 - [x] `config/apropos.php` — extracted hardcoded contacts (Laurent Leprince, Xavier Gorgol, Brigitte Ledune) and credits into a config array (`contacts[]`, `credits[]`, `erg_url`); `public/apropos.php` now loops over the config with `htmlspecialchars` instead of embedding names/emails in HTML
 - [x] `todo/02-php-components.md` — audited and marked 8 stale items as already done: all 5 form field partials (`text-field`, `select-field`, `checkbox-list`, `file-field`, `jury-fieldset`), `admin-alert.php`/`flash-messages.php` consolidation, `RateLimit` cache dir placement, and `apropos.php` contacts extraction
 
diff --git a/public/admin/actions/edit.php b/public/admin/actions/edit.php
index 5df8d5f..d74af41 100644
--- a/public/admin/actions/edit.php
+++ b/public/admin/actions/edit.php
@@ -136,6 +136,18 @@ try {
     error_log("Edit action error: " . $e->getMessage());
 
     App::flash('error', $e->getMessage());
+
+    // WCAG 3.3.1 — map error to the field that caused it so the form can autofocus it.
+    $msg = $e->getMessage();
+    $autofocusField = null;
+    if (str_contains($msg, 'titre') || str_contains($msg, 'Titre'))          $autofocusField = 'titre';
+    elseif (str_contains($msg, 'année') || str_contains($msg, 'année'))      $autofocusField = 'année';
+    elseif (str_contains($msg, 'synopsis') || str_contains($msg, 'Synopsis')) $autofocusField = 'synopsis';
+    elseif (str_contains($msg, 'auteur') || str_contains($msg, 'Auteur'))     $autofocusField = 'auteurice';
+    if ($autofocusField !== null) {
+        App::flashAutofocus($autofocusField);
+    }
+
     header('Location: ../edit.php?id=' . $thesisId);
     exit();
 }
diff --git a/public/admin/actions/formulaire.php b/public/admin/actions/formulaire.php
index 9343544..e9bcf57 100644
--- a/public/admin/actions/formulaire.php
+++ b/public/admin/actions/formulaire.php
@@ -322,6 +322,24 @@ try {
     App::flash('error', $e->getMessage());
     $_SESSION['form_data'] = $_POST;
 
+    // WCAG 3.3.1 — identify which field caused the error and request autofocus.
+    // Mapping is based on the exception messages thrown above.
+    $msg = $e->getMessage();
+    $autofocusField = null;
+    if (str_contains($msg, "Nom/Prénom/Pseudo"))        $autofocusField = 'auteurice';
+    elseif (str_contains($msg, "Titre du mémoire"))     $autofocusField = 'titre';
+    elseif (str_contains($msg, "Synopsis"))             $autofocusField = 'synopsis';
+    elseif (str_contains($msg, "Année invalide"))       $autofocusField = 'année';
+    elseif (str_contains($msg, "orientation"))          $autofocusField = 'orientation';
+    elseif (str_contains($msg, "Atelier Pratique"))     $autofocusField = 'ap';
+    elseif (str_contains($msg, "finalité"))             $autofocusField = 'finality';
+    elseif (str_contains($msg, "langue"))               $autofocusField = 'languages';
+    elseif (str_contains($msg, "mots-clés"))            $autofocusField = 'tag';
+    elseif (str_contains($msg, "Lien URL"))             $autofocusField = 'lien';
+    if ($autofocusField !== null) {
+        App::flashAutofocus($autofocusField);
+    }
+
     // Redirect back to form with preserved data
     header('Location: ../add.php');
     exit();
diff --git a/public/admin/add.php b/public/admin/add.php
index aaed1f6..a2ca581 100644
--- a/public/admin/add.php
+++ b/public/admin/add.php
@@ -24,10 +24,23 @@ try {
     die("Erreur lors du chargement du formulaire.");
 }
 
-$formData = $_SESSION["form_data"] ?? [];
-unset($_SESSION["form_data"]);
+$formData      = $_SESSION['form_data'] ?? [];
+unset($_SESSION['form_data']);
+$autofocusField = App::consumeAutofocus();
 // Flash error consumed by the flash-messages partial below.
 
+/**
+ * Merge autofocus into the $attrs array for a given field.
+ * Only adds the attribute when $autofocusField matches $fieldName.
+ */
+function withAutofocus(string $fieldName, array $attrs = []): array {
+    global $autofocusField;
+    if ($autofocusField === $fieldName) {
+        $attrs['autofocus'] = true;
+    }
+    return $attrs;
+}
+
 function old($key, $default = "") {
     global $formData;
     return isset($formData[$key]) ? htmlspecialchars($formData[$key]) : $default;
@@ -50,9 +63,9 @@ function wasSelected($key, $value) {
     <form action="actions/formulaire.php" method="post" enctype="multipart/form-data" class="admin-form">
         <input type="hidden" name="csrf_token" value="<?= htmlspecialchars($_SESSION["csrf_token"]) ?>">
 
-        <?php $name = 'titre';     $label = 'Titre :';                          $value = old('titre');     $required = true;  include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
+        <?php $name = 'titre';     $label = 'Titre :';                          $value = old('titre');     $required = true;  $attrs = withAutofocus('titre');     include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
         <?php $name = 'subtitle';  $label = 'Sous-titre (si applicable) :';     $value = old('subtitle');  $required = false; include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
-        <?php $name = 'auteurice'; $label = 'Auteur·ice(s) :';                  $value = old('auteurice'); $required = true; $attrs = ['autocomplete' => 'name'];  include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
+        <?php $name = 'auteurice'; $label = 'Auteur·ice(s) :';                  $value = old('auteurice'); $required = true; $attrs = withAutofocus('auteurice', ['autocomplete' => 'name']);  include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
         <?php $name = 'mail';      $label = 'Contact(s) (optionnel) [mail/site/insta/etc.] :'; $value = old('mail'); $attrs = ['autocomplete' => 'email']; include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
 
         <?php require APP_ROOT . '/templates/partials/form/jury-fieldset.php'; ?>
@@ -61,34 +74,35 @@ function wasSelected($key, $value) {
             $name  = 'année'; $label = 'Année :'; $value = old('année'); $required = true;
             $type  = 'number';
             $placeholder = date('Y');
-            $attrs = ['min' => 2000, 'max' => date('Y') + 1];
+            $attrs = withAutofocus('année', ['min' => 2000, 'max' => date('Y') + 1]);
             include APP_ROOT . '/templates/partials/form/text-field.php';
         ?>
 
-        <?php $name = 'orientation'; $label = 'Orientation :'; $options = $orientations; $selected = $formData['orientation'] ?? ''; $required = true; $placeholder = ''; include APP_ROOT . '/templates/partials/form/select-field.php'; ?>
+        <?php $name = 'orientation'; $label = 'Orientation :'; $options = $orientations; $selected = $formData['orientation'] ?? ''; $required = true; $placeholder = ''; $attrs = withAutofocus('orientation'); include APP_ROOT . '/templates/partials/form/select-field.php'; ?>
 
-        <?php $name = 'ap'; $label = 'Atelier pluridisciplinaire :'; $options = $apPrograms; $selected = $formData['ap'] ?? ''; $required = true; $placeholder = ''; include APP_ROOT . '/templates/partials/form/select-field.php'; ?>
+        <?php $name = 'ap'; $label = 'Atelier pluridisciplinaire :'; $options = $apPrograms; $selected = $formData['ap'] ?? ''; $required = true; $placeholder = ''; $attrs = withAutofocus('ap'); include APP_ROOT . '/templates/partials/form/select-field.php'; ?>
 
-        <?php $name = 'finality'; $label = 'Finalité du master :'; $options = $finalityTypes; $selected = $formData['finality'] ?? ''; $required = true; $placeholder = ''; include APP_ROOT . '/templates/partials/form/select-field.php'; ?>
+        <?php $name = 'finality'; $label = 'Finalité du master :'; $options = $finalityTypes; $selected = $formData['finality'] ?? ''; $required = true; $placeholder = ''; $attrs = withAutofocus('finality'); include APP_ROOT . '/templates/partials/form/select-field.php'; ?>
 
         <?php $name = 'languages'; $label = 'Langue(s) :'; $options = $languages; $checked = $formData['languages'] ?? []; include APP_ROOT . '/templates/partials/form/checkbox-list.php'; ?>
 
         <?php $name = 'formats'; $label = 'Format(s) :'; $options = $formatTypes; $checked = $formData['formats'] ?? []; include APP_ROOT . '/templates/partials/form/checkbox-list.php'; ?>
 
-        <?php $name = 'tag'; $label = 'Mots-clés :'; $value = old('tag'); $placeholder = 'sociologie, anthropologie, ...'; $hint = 'Séparez par des virgules. Max 10 mots-clés.'; include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
+        <?php $name = 'tag'; $label = 'Mots-clés :'; $value = old('tag'); $placeholder = 'sociologie, anthropologie, ...'; $hint = 'Séparez par des virgules. Max 10 mots-clés.'; $attrs = withAutofocus('tag'); include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
 
         <!-- Synopsis -->
         <div>
             <label for="synopsis">Synopsis :</label>
             <textarea id="synopsis" name="synopsis"
-                      rows="7" required><?= old('synopsis') ?></textarea>
+                      rows="7" required
+                      <?= $autofocusField === 'synopsis' ? 'autofocus' : '' ?>><?= old('synopsis') ?></textarea>
         </div>
 
         <?php $name = 'license_id'; $label = 'Licence :'; $options = $licenseTypes; $selected = $formData['license_id'] ?? ''; $placeholder = '— Inconnue —'; include APP_ROOT . '/templates/partials/form/select-field.php'; ?>
 
         <?php $name = 'duration_info'; $label = 'Durée / Taille :'; $value = old('duration_info'); $placeholder = 'Ex : 84 pages'; $hint = 'Durée (minutes) ou nombre de pages.'; include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
 
-        <?php $name = 'lien'; $label = 'Lien (site / ressource) :'; $value = old('lien'); $type = 'url'; $placeholder = 'https://...'; include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
+        <?php $name = 'lien'; $label = 'Lien (site / ressource) :'; $value = old('lien'); $type = 'url'; $placeholder = 'https://...'; $attrs = withAutofocus('lien'); include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
 
         <?php $name = 'couverture'; $label = 'Image de couverture :'; $accept = 'image/jpeg,image/png'; $hint = 'JPG, PNG. Taille max : 10 MB.'; include APP_ROOT . '/templates/partials/form/file-field.php'; ?>
 
diff --git a/public/admin/edit.php b/public/admin/edit.php
index a6a3d75..ae97e10 100644
--- a/public/admin/edit.php
+++ b/public/admin/edit.php
@@ -53,6 +53,9 @@ try {
     // Set page title for header
     $pageTitle = "Éditer TFE - " . htmlspecialchars($thesis['title']);
 
+    // WCAG 3.3.1 — consume the autofocus hint stored by the edit action on validation failure.
+    $autofocusField = App::consumeAutofocus();
+
 } catch (Exception $e) {
     error_log("Error loading edit page: " . $e->getMessage());
     die("Erreur lors du chargement: " . $e->getMessage());
@@ -70,12 +73,13 @@ try {
         <input type="hidden" name="csrf_token" value="<?= htmlspecialchars($_SESSION['csrf_token']) ?>">
         <input type="hidden" name="thesis_id"  value="<?= $thesisId ?>">
 
-        <?php $name = 'auteurice'; $label = 'Auteur·ice(s) :'; $value = htmlspecialchars($thesis['authors']); $required = true; $attrs = ['autocomplete' => 'name'];  include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
+        <?php $name = 'auteurice'; $label = 'Auteur·ice(s) :'; $value = htmlspecialchars($thesis['authors']); $required = true; $attrs = array_merge(['autocomplete' => 'name'], $autofocusField === 'auteurice' ? ['autofocus' => true] : []);  include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
         <?php $name = 'mail';      $label = 'Contact :';        $value = '';                                   $attrs = ['autocomplete' => 'email']; include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
 
         <?php
             $name  = 'année'; $label = 'Année :'; $value = htmlspecialchars((string)$thesis['year']); $required = true;
             $type  = 'number';
+            $attrs = $autofocusField === 'année' ? ['autofocus' => true] : [];
             include APP_ROOT . '/templates/partials/form/text-field.php';
         ?>
 
@@ -129,13 +133,14 @@ try {
 
         <?php $name = 'license_id'; $label = 'Licence :'; $options = $licenseTypes; $selected = $currentLicenseId; $placeholder = '- Inconnue -'; include APP_ROOT . '/templates/partials/form/select-field.php'; ?>
 
-        <?php $name = 'titre';    $label = 'Titre :';      $value = htmlspecialchars($thesis['title']);           $required = true; include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
+        <?php $name = 'titre';    $label = 'Titre :';      $value = htmlspecialchars($thesis['title']);           $required = true; $attrs = $autofocusField === 'titre' ? ['autofocus' => true] : []; include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
         <?php $name = 'subtitle'; $label = 'Sous-titre :'; $value = htmlspecialchars($thesis['subtitle'] ?? ''); include APP_ROOT . '/templates/partials/form/text-field.php'; ?>
 
         <!-- Synopsis (textarea — not covered by text-field partial) -->
         <div>
             <label for="synopsis">Synopsis :</label>
-            <textarea id="synopsis" name="synopsis" rows="7" required><?= htmlspecialchars($thesis['synopsis'] ?? '') ?></textarea>
+            <textarea id="synopsis" name="synopsis" rows="7" required
+                      <?= $autofocusField === 'synopsis' ? 'autofocus' : '' ?>><?= htmlspecialchars($thesis['synopsis'] ?? '') ?></textarea>
         </div>
 
         <?php $name = 'languages'; $label = 'Langue(s) :'; $options = $languages; $checked = $currentLanguages; include APP_ROOT . '/templates/partials/form/checkbox-list.php'; ?>
diff --git a/src/App.php b/src/App.php
index d72c94d..74487ea 100644
--- a/src/App.php
+++ b/src/App.php
@@ -83,6 +83,26 @@ class App
         $_SESSION["_flash_{$type}"] = $message;
     }
 
+    /**
+     * Store the name of the field that should receive autofocus after a
+     * validation failure (WCAG 3.3.1).
+     */
+    public static function flashAutofocus(string $fieldName): void
+    {
+        $_SESSION['_flash_autofocus'] = $fieldName;
+    }
+
+    /**
+     * Consume and return the autofocus field name, then clear it.
+     * Returns null when no autofocus hint is present.
+     */
+    public static function consumeAutofocus(): ?string
+    {
+        $field = $_SESSION['_flash_autofocus'] ?? null;
+        unset($_SESSION['_flash_autofocus']);
+        return $field;
+    }
+
     /**
      * Consume and return flash messages, then clear them from the session.
      *
@@ -117,6 +137,7 @@ class App
             $_SESSION['form_error']
         );
 
+        // Note: autofocus is consumed separately via consumeAutofocus().
         return ['error' => $error, 'success' => $success];
     }
 
diff --git a/templates/partials/form/select-field.php b/templates/partials/form/select-field.php
index 6b95a1a..24ec4b6 100644
--- a/templates/partials/form/select-field.php
+++ b/templates/partials/form/select-field.php
@@ -20,12 +20,24 @@ $required    = $required    ?? false;
 $placeholder = array_key_exists('placeholder', get_defined_vars()) ? $placeholder : '';
 $id          = $id          ?? $name;
 $hint        = $hint        ?? null;
+$attrs       = $attrs       ?? [];
 ?>
 <div>
     <label for="<?= htmlspecialchars($id) ?>"><?= htmlspecialchars($label) ?></label>
+<?php
+$selectAttrStr = '';
+foreach ($attrs as $k => $v) {
+    if ($v === true) {
+        $selectAttrStr .= ' ' . htmlspecialchars($k);
+    } else {
+        $selectAttrStr .= ' ' . htmlspecialchars($k) . '="' . htmlspecialchars((string)$v) . '"';
+    }
+}
+?>
     <select id="<?= htmlspecialchars($id) ?>"
             name="<?= htmlspecialchars($name) ?>"
-            <?= $required ? 'required' : '' ?>>
+            <?= $required ? 'required' : '' ?>
+            <?= $selectAttrStr ?>>
         <?php if ($placeholder !== null): ?>
         <option value=""><?= htmlspecialchars($placeholder) ?></option>
         <?php endif; ?>
@@ -46,4 +58,4 @@ $hint        = $hint        ?? null;
     <?php endif; ?>
 </div>
 <?php
-unset($required, $placeholder, $id, $hint);
+unset($required, $placeholder, $id, $hint, $attrs, $selectAttrStr, $k, $v);
diff --git a/templates/partials/form/text-field.php b/templates/partials/form/text-field.php
index 821fd74..5a1e1f5 100644
--- a/templates/partials/form/text-field.php
+++ b/templates/partials/form/text-field.php
@@ -25,7 +25,11 @@ $attrs       = $attrs       ?? [];
 
 $attrStr = '';
 foreach ($attrs as $k => $v) {
-    $attrStr .= ' ' . htmlspecialchars($k) . '="' . htmlspecialchars((string)$v) . '"';
+    if ($v === true) {
+        $attrStr .= ' ' . htmlspecialchars($k);
+    } else {
+        $attrStr .= ' ' . htmlspecialchars($k) . '="' . htmlspecialchars((string)$v) . '"';
+    }
 }
 ?>
 <div>
diff --git a/todo/04-accessibility.md b/todo/04-accessibility.md
index 0048753..d1063e7 100644
--- a/todo/04-accessibility.md
+++ b/todo/04-accessibility.md
@@ -58,7 +58,7 @@
 ## 3.3.1 Error identification
 
 - [x] **`add.php`/`edit.php` validation errors** — `flash-messages.php` already emits `<p role="alert" data-type="error">` for errors and `<p role="status">` for success
-- [ ] **`add.php`/`edit.php` `autofocus` on first invalid field** — requires controller to pass back which field failed; deferred (larger refactor)
+- [x] **`add.php`/`edit.php` `autofocus` on first invalid field** — `App::flashAutofocus(fieldName)` stores the failing field in `$_SESSION['_flash_autofocus']`; action handlers map exception messages to field names; `add.php` consumes via `withAutofocus()` helper + injects into `$attrs`; `edit.php` uses inline ternary; partials support boolean `true` in `$attrs` to emit bare attribute names
 
 ## 3.3.2 Labels or instructions