diff --git a/fusion_plating/fusion_plating_bridge_mrp/__manifest__.py b/fusion_plating/fusion_plating_bridge_mrp/__manifest__.py
index 55e962fe..a413733a 100644
--- a/fusion_plating/fusion_plating_bridge_mrp/__manifest__.py
+++ b/fusion_plating/fusion_plating_bridge_mrp/__manifest__.py
@@ -5,7 +5,7 @@
 
 {
     "name": "Fusion Plating — MRP Bridge",
-    'version': '19.0.6.3.0',
+    'version': '19.0.6.4.0',
     'category': 'Manufacturing/Plating',
     'summary': 'Bridge Fusion Plating facilities, baths and tanks to Odoo MRP work orders.',
     'description': """
diff --git a/fusion_plating/fusion_plating_bridge_mrp/models/mrp_workorder.py b/fusion_plating/fusion_plating_bridge_mrp/models/mrp_workorder.py
index 9bd57f1c..9a2180fd 100644
--- a/fusion_plating/fusion_plating_bridge_mrp/models/mrp_workorder.py
+++ b/fusion_plating/fusion_plating_bridge_mrp/models/mrp_workorder.py
@@ -26,6 +26,13 @@ class MrpWorkorder(models.Model):
     # ------------------------------------------------------------------
     # Plating-specific fields
     # ------------------------------------------------------------------
+    x_fc_requires_bath = fields.Boolean(
+        string='Requires Bath/Tank',
+        compute='_compute_requires_bath',
+        store=False,
+        help='True when this WO involves a chemistry bath. Surfaced to '
+             'the form view so bath/tank fields render as required.',
+    )
     x_fc_bath_id = fields.Many2one(
         'fusion.plating.bath', string='Bath', tracking=True,
     )
@@ -512,10 +519,82 @@ class MrpWorkorder(models.Model):
 
     # ------------------------------------------------------------------
     # T2.2 — Certification gate on WO start
+    # T2.3 — Required-field gate (bath/tank for wet WOs, assigned operator)
     # ------------------------------------------------------------------
+    WET_FAMILIES = (
+        'plating', 'pre_treatment', 'post_treatment',
+        'strip', 'passivation',
+    )
+    # Keyword fallback used when the workcenter / process-type metadata
+    # is missing — covers most shop floor naming conventions. Lowercased.
+    WET_NAME_KEYWORDS = (
+        'plat', 'nickel', 'chrome', 'anodiz', 'zinc',
+        'etch', 'clean', 'rinse', 'strip', 'passivat',
+        'zincate', 'alkalin', 'acid', 'electroless',
+    )
+
+    @api.depends('x_fc_bath_id', 'name', 'workcenter_id')
+    def _compute_requires_bath(self):
+        for wo in self:
+            wo.x_fc_requires_bath = wo._fp_is_wet_process()
+
+    def _fp_is_wet_process(self):
+        """Best-effort check: does this WO involve a chemistry bath?
+
+        Three signals, in priority order:
+          1. A bath is already linked → definitely wet
+          2. The workcenter's FP work-centre supports a wet process family
+          3. The WO's name contains a wet-process keyword
+        """
+        self.ensure_one()
+        if self.x_fc_bath_id:
+            return True
+        wc = self.workcenter_id
+        fpwc = getattr(wc, 'x_fc_fp_work_center_id', False)
+        if fpwc:
+            families = set(fpwc.supported_process_ids.mapped('process_family'))
+            if families & set(self.WET_FAMILIES):
+                return True
+        name = (self.name or '').lower()
+        return any(k in name for k in self.WET_NAME_KEYWORDS)
+
+    def _fp_check_required_fields_before_start(self):
+        """Block button_start if the WO is missing data the shop must
+        record for traceability + compliance.
+
+        Rules:
+          • Every WO needs an assigned operator (x_fc_assigned_user_id) —
+            without it, productivity records can't be attributed and
+            proficiency tracking goes nowhere.
+          • Wet (bath) WOs additionally need x_fc_bath_id + x_fc_tank_id —
+            for chemistry traceability and physical-location audit
+            (which exact tank ran the job).
+        """
+        from odoo.exceptions import UserError
+        for wo in self:
+            missing = []
+            if not wo.x_fc_assigned_user_id:
+                missing.append(_('Assigned Operator'))
+            if wo._fp_is_wet_process():
+                if not wo.x_fc_bath_id:
+                    missing.append(_('Bath'))
+                if not wo.x_fc_tank_id:
+                    missing.append(_('Tank'))
+            if missing:
+                raise UserError(_(
+                    'Cannot start work order "%(wo)s" — please fill these '
+                    'required fields first:\n  • %(fields)s\n\n'
+                    'Open the work order form and have the planner set them.'
+                ) % {
+                    'wo': wo.display_name or wo.name,
+                    'fields': '\n  • '.join(missing),
+                })
+
     def button_start(self):
         """Block start unless the current user's linked employee holds
-        an active certification for this WO's process type."""
+        an active certification for this WO's process type AND every
+        required field for traceability is filled in."""
+        self._fp_check_required_fields_before_start()
         self._fp_check_operator_certification()
         res = super().button_start()
         # Capture audit AFTER the super call so we don't stamp WOs that
diff --git a/fusion_plating/fusion_plating_bridge_mrp/views/mrp_workorder_views.xml b/fusion_plating/fusion_plating_bridge_mrp/views/mrp_workorder_views.xml
index 590a711a..7145ead3 100644
--- a/fusion_plating/fusion_plating_bridge_mrp/views/mrp_workorder_views.xml
+++ b/fusion_plating/fusion_plating_bridge_mrp/views/mrp_workorder_views.xml
@@ -93,8 +93,10 @@
                 <field name="x_fc_priority" widget="priority"/>
                 <field name="x_fc_assigned_user_id"
                        string="Assigned To"
+                       required="1"
                        options="{'no_create': True}"/>
                 <field name="x_fc_work_role_id" readonly="1"/>
+                <field name="x_fc_requires_bath" invisible="1"/>
             </xpath>
 
             <!-- ============================================================
@@ -166,8 +168,10 @@
                     <group>
                         <group string="Bath &amp; Tank">
                             <field name="x_fc_facility_id"/>
-                            <field name="x_fc_bath_id"/>
-                            <field name="x_fc_tank_id"/>
+                            <field name="x_fc_bath_id"
+                                   required="x_fc_requires_bath"/>
+                            <field name="x_fc_tank_id"
+                                   required="x_fc_requires_bath"/>
                             <field name="x_fc_rack_id"/>
                             <field name="x_fc_rack_ref"/>
                         </group>
diff --git a/fusion_plating/scripts/fp_audit_workorders.py b/fusion_plating/scripts/fp_audit_workorders.py
new file mode 100644
index 00000000..0695a64d
--- /dev/null
+++ b/fusion_plating/scripts/fp_audit_workorders.py
@@ -0,0 +1,11 @@
+env = env  # noqa
+recipe = env['fusion.plating.process.node'].search(
+    [('node_type', '=', 'recipe'), ('name', '=', 'ENP-ALUM-BASIC')], limit=1)
+print(f'Recipe: {recipe.name}')
+def walk(node, indent=0):
+    pt = node.process_type_id.process_family if node.process_type_id else '(none)'
+    wc = node.work_center_id.name if node.work_center_id else '(none)'
+    print(f'{"  "*indent}- [{node.node_type:9}] {node.name!r:35} pt_family={pt!r:18} wc={wc}')
+    for c in node.child_ids.sorted('sequence'):
+        walk(c, indent+1)
+walk(recipe)
diff --git a/fusion_plating/scripts/fp_e2e_workforce.py b/fusion_plating/scripts/fp_e2e_workforce.py
index 2a49a08c..cbbe3ede 100644
--- a/fusion_plating/scripts/fp_e2e_workforce.py
+++ b/fusion_plating/scripts/fp_e2e_workforce.py
@@ -223,7 +223,39 @@ WO_OPERATORS = {
 }
 
 step('HANNAH', 'Assigns each WO to a specific operator')
+# Pick a bath + a tank for any WO that needs wet-process traceability
+test_bath = env['fusion.plating.bath'].search([], limit=1)
+test_tank = env['fusion.plating.tank'].search([], limit=1)
+
+# Issue operator certifications for the bath's process type so the cert
+# gate doesn't block legitimate operators (in real life the manager
+# tracks training + issues certs; for a clean E2E we pre-issue).
+Cert = env.get('fp.operator.certification')
+if Cert is not None and test_bath and test_bath.process_type_id:
+    pt = test_bath.process_type_id
+    for op_key in ('john', 'maria', 'tom', 'ana', 'frank'):
+        emp = env['hr.employee'].search(
+            [('user_id', '=', users[op_key].id)], limit=1)
+        if not emp:
+            continue
+        existing = Cert.sudo().search([
+            ('employee_id', '=', emp.id),
+            ('process_type_id', '=', pt.id),
+            ('revoked', '=', False),
+        ], limit=1)
+        if not existing:
+            Cert.sudo().create({
+                'employee_id': emp.id,
+                'process_type_id': pt.id,
+                'issued_by_id': users['hannah'].id,
+                'notes': 'Auto-issued for E2E workforce simulation',
+            })
+    show('  certifications', f'pre-issued for {pt.name} → 5 operators')
+show('  test bath', f'{test_bath.name}' if test_bath else '(none — wet-WO assignment will fail)')
+show('  test tank', f'{test_tank.name}' if test_tank else '(none — wet-WO assignment will fail)')
+
 assignments = []
+wet_assignments = []
 for wo in mo.workorder_ids:
     name_l = (wo.name or '').lower()
     operator_key = None
@@ -231,16 +263,79 @@ for wo in mo.workorder_ids:
         if kw in name_l:
             operator_key = k
             break
-    operator_key = operator_key or 'john'  # fallback
+    operator_key = operator_key or 'john'
     op_user = users[operator_key]
     wo.sudo().x_fc_assigned_user_id = op_user.id
+
+    # If this is a wet-process WO (E-Nickel Plating, etch, rinse, etc.)
+    # Hannah must also pin the exact bath + tank for traceability.
+    is_wet = wo._fp_is_wet_process() if hasattr(wo, '_fp_is_wet_process') else False
+    bath_assigned = tank_assigned = False
+    if is_wet and test_bath and test_tank:
+        wo.sudo().write({
+            'x_fc_bath_id': test_bath.id,
+            'x_fc_tank_id': test_tank.id,
+        })
+        bath_assigned = True
+        tank_assigned = True
+        wet_assignments.append(wo)
+
     assignments.append((wo, op_user, operator_key))
-    show(f'  WO {wo.id}', f'"{wo.name}" → {op_user.name}')
+    extras = ''
+    if is_wet:
+        extras = f'  [WET — bath={test_bath.name if bath_assigned else "MISSING"}, tank={test_tank.name if tank_assigned else "MISSING"}]'
+    show(f'  WO {wo.id}', f'"{wo.name}" → {op_user.name}{extras}')
 
 assigned_count = sum(1 for w, _, _ in assignments if w.x_fc_assigned_user_id)
 finding('PASS' if assigned_count == n_wos else 'FAIL',
         'WO assignment', f'{assigned_count}/{n_wos} have x_fc_assigned_user_id')
 
+wet_with_bath = sum(1 for w in wet_assignments if w.x_fc_bath_id and w.x_fc_tank_id)
+finding('PASS' if (not wet_assignments) or (wet_with_bath == len(wet_assignments)) else 'FAIL',
+        'wet-WO bath+tank set',
+        f'{wet_with_bath}/{len(wet_assignments)} wet WOs have both bath + tank')
+
+# ===== Negative tests: validation MUST block bad starts =====
+banner('PHASE 4b — Negative tests: validation gates fire correctly')
+
+# Test 1: try to start a WO with operator stripped → expect UserError
+step('SYSTEM', 'Test 1 — un-assigning operator and trying to start')
+test_wo = mo.workorder_ids[0]
+saved_op = test_wo.x_fc_assigned_user_id.id
+test_wo.sudo().x_fc_assigned_user_id = False
+gate_fired = False
+try:
+    test_wo.sudo().button_start()
+except Exception as e:
+    gate_fired = 'Assigned Operator' in str(e) or 'required' in str(e).lower()
+    show('  blocked with', str(e).splitlines()[0][:120])
+finding('PASS' if gate_fired else 'FAIL',
+        'gate: missing operator',
+        'blocked' if gate_fired else 'NOT blocked — validation broken')
+test_wo.sudo().x_fc_assigned_user_id = saved_op
+
+# Test 2: try to start a WET WO without bath/tank → expect UserError
+if wet_assignments:
+    step('SYSTEM', 'Test 2 — wet WO with bath/tank stripped')
+    wet_wo = wet_assignments[0]
+    saved_bath = wet_wo.x_fc_bath_id.id
+    saved_tank = wet_wo.x_fc_tank_id.id
+    wet_wo.sudo().write({'x_fc_bath_id': False, 'x_fc_tank_id': False})
+    gate_fired = False
+    try:
+        wet_wo.sudo().button_start()
+    except Exception as e:
+        msg = str(e)
+        gate_fired = ('Bath' in msg and 'Tank' in msg) or 'required' in msg.lower()
+        show('  blocked with', msg.splitlines()[0][:120])
+    finding('PASS' if gate_fired else 'FAIL',
+            'gate: missing bath/tank on wet WO',
+            'blocked' if gate_fired else 'NOT blocked — validation broken')
+    wet_wo.sudo().write({
+        'x_fc_bath_id': saved_bath,
+        'x_fc_tank_id': saved_tank,
+    })
+
 # =====================================================================
 banner('PHASE 5 — Operators run their work orders (REAL-TIME timers)')
 # =====================================================================