feat(plating): hard-required fields on WO start — operator + bath + tank

User audit caught: in the workforce E2E run we had no idea which bath /
which tank ran the job. For aerospace traceability that's a deal-
breaker. Add a validation gate on mrp.workorder.button_start so
operators can't tap START without the data the shop floor MUST capture.

**Three new pieces on mrp.workorder:**

1. `_fp_is_wet_process()` — best-effort "does this WO involve a
   chemistry bath?" check. Three signals in priority order:
   a. A bath is already linked → definitely wet
   b. The workcenter's FP work-centre supports a wet process family
      (plating, pre/post-treatment, strip, passivation)
   c. WO name contains a wet-process keyword (plat, nickel, chrome,
      anodiz, zinc, etch, clean, rinse, strip, passivat, electroless…)
   The keyword fallback is needed because most existing recipes have
   no process_type_id set on their operation nodes.

2. `_fp_check_required_fields_before_start()` — runs before the
   existing certification check. Rules:
   • Every WO needs an assigned operator (x_fc_assigned_user_id).
     Without it, productivity records can't be attributed and the
     proficiency tracker has no employee to credit.
   • Wet WOs additionally need x_fc_bath_id + x_fc_tank_id. So we
     know exactly which chemistry bath ran the job and which physical
     tank it sat in.
   Raises a clear UserError listing the missing fields if any.

3. `x_fc_requires_bath` (compute, non-stored) — surfaces the wet check
   to the form view so bath + tank fields render with `required=`.

**View changes:**
- `x_fc_assigned_user_id` is now `required="1"` on the form
- `x_fc_bath_id` + `x_fc_tank_id` use `required="x_fc_requires_bath"`
  → red asterisk only when the WO is actually wet

**Simulator updates** (scripts/fp_e2e_workforce.py):
- Hannah now explicitly assigns bath + tank to wet WOs during planning,
  AND pre-issues operator certifications for the bath's process type
  (real shop manager workflow).
- Two negative tests added that PROVE the gates fire:
  • Test 1: strip the operator → button_start raises "missing Assigned Operator"
  • Test 2: strip bath/tank on a wet WO → button_start raises "missing Bath/Tank"

**Final E2E:** 42 PASS / 2 WARN / 0 FAIL out of 44 checks.
Both remaining WARNs (bake-window auto-create, first-piece gate) are
expected behaviour — those are coating-driven and the test coating
intentionally doesn't trigger them.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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