fix(certificates): honour recipe thickness suppression at cert issue

The recipe-cert-toggles feature (fb6cccc8) taught
fp.job._resolve_required_cert_types to suppress thickness for recipes
with requires_thickness_report=False (passivation, chemical conversion,
anodize seal-only). But the actual thickness-data ENFORCEMENT never got
the memo: both fp.certificate.action_issue's hard gate AND the
Issue-Certs wizard's readiness hint re-derived 'needs thickness' from
partner flags only and ignored the recipe. Result: a passivation CoC for
a thickness/strict customer could never be issued — the gate demanded
Fischerscope data the process physically cannot produce.

Consolidate the partner-flag + recipe-suppression logic into one
fp.certificate._fp_needs_thickness_data() helper and route both the gate
and the wizard through it, so the cert-type resolver and the issue-time
gate can never drift again. Add regression tests: passivation recipe
suppresses the issue gate even for strict-thickness customers; a normal
recipe still enforces (control, guards aerospace).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

fusion_plating/fusion_plating_certificates/models/fp_certificate.py

@@ -436,6 +436,47 @@ class FpCertificate(models.Model):
                 rec.invalidate_recordset(['name'])
         return records
 
+    def _fp_needs_thickness_data(self):
+        """True when this cert MUST carry thickness data to be issued.
+
+        Single source of truth shared by action_issue (hard gate) and the
+        Issue-Certs wizard (readiness hint) so the two can never drift.
+
+        Partner side — the ceiling: a CoC needs thickness when the customer
+        is strict-thickness (aerospace / Nadcap) or opts into the
+        thickness-on-CoC bundle; a thickness_report cert always needs it.
+
+        Recipe side — suppress-only: a recipe whose requires_thickness_report
+        is False (passivation, chemical conversion, anodize seal-only — no
+        plating thickness physically exists) REMOVES the requirement even
+        when the customer asked. This mirrors Step 2 of
+        fp.job._resolve_required_cert_types so the cert-type resolver and
+        this issue-time gate agree. Without it, a passivation CoC for a
+        thickness customer can never be issued (the gate demands Fischerscope
+        data the process cannot produce). Field-existence guards keep this
+        safe when fusion_plating_jobs / fusion_plating are at an older
+        schema or not installed.
+        """
+        self.ensure_one()
+        partner = self.partner_id
+        needs = (
+            self.certificate_type == 'thickness_report'
+            or (self.certificate_type == 'coc' and partner and (
+                ('x_fc_strict_thickness_required' in partner._fields
+                 and partner.x_fc_strict_thickness_required)
+                or ('x_fc_send_thickness_report' in partner._fields
+                    and partner.x_fc_send_thickness_report)
+            ))
+        )
+        if not needs:
+            return False
+        job = self.x_fc_job_id if 'x_fc_job_id' in self._fields else False
+        recipe = job.recipe_id if job else False
+        if (recipe and 'requires_thickness_report' in recipe._fields
+                and not recipe.requires_thickness_report):
+            return False
+        return True
+
     # ----- State actions ----------------------------------------------------
     def action_issue(self):
         # ===== ACL guard (spec 2026-05-25 §ACL changes) ===============
@@ -580,30 +621,18 @@ class FpCertificate(models.Model):
                     'type': type_label,
                     'name': rec.name or rec.display_name,
                 })
-            # Thickness data requirement — unified gate covering both
-            # cert types. A customer needs thickness data on the cert
-            # when ANY of these is true:
-            #   1. cert type is thickness_report (the cert IS the data)
-            #   2. partner.x_fc_strict_thickness_required (aerospace /
-            #      Nadcap — always strict)
-            #   3. partner.x_fc_send_thickness_report (the bundling
-            #      rule — CoC carries thickness as page 2 by default
-            #      for these customers; see CLAUDE.md "CoC + thickness
-            #      = ONE cert (page 2 merge)")
-            # Acceptable data: logged readings on the cert OR a
-            # Fischerscope PDF on the linked QC OR a cert-local
-            # Fischerscope upload. Any one is enough.
+            # Thickness data requirement — _fp_needs_thickness_data is the
+            # single source of truth (shared with the Issue-Certs wizard).
+            # A customer needs thickness data when the cert is a
+            # thickness_report, or it's a CoC and the partner is
+            # strict-thickness / opts into the thickness-on-CoC bundle —
+            # UNLESS the job's recipe suppresses thickness
+            # (requires_thickness_report=False: passivation, chemical
+            # conversion, anodize seal-only — no plating thickness exists).
+            # Acceptable data: logged readings on the cert OR a Fischerscope
+            # PDF on the linked QC OR a cert-local Fischerscope upload.
             partner = rec.partner_id
-            needs_thickness = (
-                rec.certificate_type == 'thickness_report'
-                or (rec.certificate_type == 'coc' and partner and (
-                    ('x_fc_strict_thickness_required' in partner._fields
-                     and partner.x_fc_strict_thickness_required)
-                    or ('x_fc_send_thickness_report' in partner._fields
-                        and partner.x_fc_send_thickness_report)
-                ))
-            )
-            if needs_thickness:
+            if rec._fp_needs_thickness_data():
                 has_readings = bool(rec.thickness_reading_ids)
                 has_qc_fischer_pdf = bool(
                     rec.x_fc_thickness_pdf_id