fix(fusion_plating_jobs): gating steps fall forward to next stage's column

A "Ready for X" gating step (fp.step.kind code='gating') maps to
area_kind='receiving' in the taxonomy. For a MID-recipe gate (e.g.
"Ready for processing" between Racking and Plating) that snapped the
job's card back to the far-left Receiving column when work advanced into
it — the job looked like it vanished from the board.

_compute_area_kind now detects gating via the stable kind code and
resolves a gating step's column to the NEXT non-gating step's area (so
"Ready for processing" shows in Plating), keeping cards flowing
left→right. Falls back to the last real stage for a trailing gate.
Non-gating steps unchanged. Helpers: _fp_is_gating_step / _fp_raw_area_kind
(no recursion) / _fp_resolve_area_kind.

area_kind is a stored compute — recomputed all 537 live steps on entech.
Verified: WO-30061 "Ready for processing" area receiving→plating, card now
renders in the Plating column.

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

fusion_plating/fusion_plating_jobs/models/fp_job_step.py

@@ -157,33 +157,71 @@ class FpJobStep(models.Model):
     @api.depends(
         'work_centre_id.area_kind',
         'recipe_node_id.kind_id.area_kind',
+        'recipe_node_id.kind_id.code',
+        'sequence',
+        'job_id.step_ids.sequence',
+        'job_id.step_ids.work_centre_id.area_kind',
+        'job_id.step_ids.recipe_node_id.kind_id.area_kind',
+        'job_id.step_ids.recipe_node_id.kind_id.code',
     )
     def _compute_area_kind(self):
         """Resolve the plant-view column this step belongs in.
 
-        Priority chain:
+        Priority chain (non-gating steps):
           1. work_centre.area_kind (explicit operator setup wins)
           2. recipe_node.kind_id.area_kind (kind taxonomy authoritative)
           3. catch-all 'plating' (data integrity issue if we land here)
 
-        The legacy _STEP_KIND_TO_AREA dict was removed — fp.step.kind
-        now self-declares its area_kind, so the kind taxonomy IS the
-        source of truth. See spec
-        2026-05-24-shopfloor-live-step-fix-design.md Change 6.
+        Gating/marker steps (kind `code == 'gating'` — the "Ready for X"
+        steps) have NO physical location; the taxonomy maps them to
+        'receiving', which made a mid-recipe gate snap the job's card back
+        to the first column (Racking -> "Ready for processing" jumped to
+        Receiving, so the job looked like it vanished — 2026-06-02). A
+        gating step now FALLS FORWARD to the next non-gating step's column
+        (it's "ready for [that stage]"), keeping the card moving
+        left->right. If nothing real follows, it falls back to the last
+        real stage.
         """
         for step in self:
-            # 1. Explicit work_centre wins
-            if step.work_centre_id and step.work_centre_id.area_kind:
-                step.area_kind = step.work_centre_id.area_kind
-                continue
-            # 2. Kind taxonomy
-            node = step.recipe_node_id
-            if node and node.kind_id and node.kind_id.area_kind:
-                step.area_kind = node.kind_id.area_kind
-                continue
-            # 3. Catch-all — only reached for orphaned steps (no
-            # work_centre AND no recipe_node).
-            step.area_kind = 'plating'
+            step.area_kind = step._fp_resolve_area_kind()
+
+    def _fp_raw_area_kind(self):
+        """Area from this step's OWN work_centre / kind only — no look-ahead
+        and no dependence on the computed `area_kind` field (so the gating
+        fall-forward below can't recurse)."""
+        self.ensure_one()
+        if self.work_centre_id and self.work_centre_id.area_kind:
+            return self.work_centre_id.area_kind
+        node = self.recipe_node_id
+        if node and node.kind_id and node.kind_id.area_kind:
+            return node.kind_id.area_kind
+        return 'plating'
+
+    def _fp_is_gating_step(self):
+        """True for a 'Ready for X' marker step (no physical location).
+        Detected via the STABLE kind code, never the display name."""
+        self.ensure_one()
+        node = self.recipe_node_id
+        return bool(node and node.kind_id and node.kind_id.code == 'gating')
+
+    def _fp_resolve_area_kind(self):
+        """Column for this step: its own raw area, EXCEPT a gating marker
+        falls forward to the next non-gating step's column."""
+        self.ensure_one()
+        if not self._fp_is_gating_step():
+            return self._fp_raw_area_kind()
+        siblings = self.job_id.step_ids
+        later = siblings.filtered(
+            lambda s: s.sequence > self.sequence and not s._fp_is_gating_step()
+        ).sorted('sequence')
+        if later:
+            return later[0]._fp_raw_area_kind()
+        earlier = siblings.filtered(
+            lambda s: s.sequence < self.sequence and not s._fp_is_gating_step()
+        ).sorted('sequence')
+        if earlier:
+            return earlier[-1]._fp_raw_area_kind()
+        return self._fp_raw_area_kind()
 
     last_activity_at = fields.Datetime(
         string='Last Activity',