feat(fusion_plating_jobs): fp.job.step blocker_kind/reason/jump_target computes

Plan task P1.2. Reuses _fp_should_block_predecessors so the new compute
stays in sync with the existing can_start logic. Drives the OWL GateViz
component on the tablet — "Can't start yet — Waiting on Step N: X".

Future work: extend with explicit branches for contract_review /
parts_not_received / racking_required / manager_input as those gate
models mature.

Tests not run locally (no fusion_plating mount in odoo-modsdev).
Verify on entech: -u fusion_plating_jobs --test-tags fp_jobs.

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

fusion_plating/fusion_plating_jobs/tests/__init__.py

@@ -2,3 +2,5 @@
 from . import test_fp_job_extensions
 from . import test_fp_job_milestone_cascade
 from . import test_qty_received_propagation
+from . import test_display_wo_name
+from . import test_blocker_compute

fusion_plating/fusion_plating_jobs/tests/test_blocker_compute.py

@@ -0,0 +1,70 @@
+# -*- coding: utf-8 -*-
+# Copyright 2026 Nexa Systems Inc. — License OPL-1
+from odoo.tests.common import TransactionCase, tagged
+
+
+@tagged('-at_install', 'post_install', 'fp_jobs')
+class TestBlockerCompute(TransactionCase):
+    """fp.job.step.blocker_kind / blocker_reason / blocker_jump_target_*
+    — Gate visualizer source of truth for the OWL GateViz component.
+    """
+
+    def setUp(self):
+        super().setUp()
+        self.partner = self.env['res.partner'].create({'name': 'Test Cust'})
+        self.product = self.env['product.product'].create({'name': 'Test Prod'})
+        self.job = self.env['fp.job'].create({
+            'name': 'WH/JOB/T1',
+            'partner_id': self.partner.id,
+            'product_id': self.product.id,
+            'qty': 1,
+        })
+
+    def _make_step(self, name, sequence, state='ready'):
+        return self.env['fp.job.step'].create({
+            'job_id': self.job.id,
+            'name': name,
+            'sequence': sequence,
+            'state': state,
+        })
+
+    def test_terminal_step_has_no_blocker(self):
+        step = self._make_step('Done step', 10, state='done')
+        self.assertEqual(step.blocker_kind, 'none')
+        self.assertEqual(step.blocker_reason, '')
+
+    def test_in_progress_step_has_no_blocker(self):
+        step = self._make_step('Running step', 10, state='in_progress')
+        self.assertEqual(step.blocker_kind, 'none')
+
+    def test_solo_ready_step_not_blocked(self):
+        step = self._make_step('Solo', 10, state='ready')
+        # No predecessor → blocker_kind = 'none'
+        self.assertEqual(step.blocker_kind, 'none')
+        self.assertEqual(step.blocker_reason, '')
+
+    def test_predecessor_open_blocks(self):
+        s1 = self._make_step('Earlier', 10, state='in_progress')
+        s2 = self._make_step('Later', 20, state='ready')
+        # If recipe enforces sequential OR step requires predecessor,
+        # blocker_kind should be 'predecessor'. Default depends on job
+        # config; if neither flag triggers we'd see 'none' instead.
+        s2.invalidate_recordset([
+            'blocker_kind', 'blocker_reason',
+            'blocker_jump_target_model', 'blocker_jump_target_id',
+        ])
+        if s2._fp_should_block_predecessors():
+            self.assertEqual(s2.blocker_kind, 'predecessor')
+            self.assertIn(s1.name, s2.blocker_reason or '')
+            self.assertEqual(s2.blocker_jump_target_model, 'fp.job.step')
+            self.assertEqual(s2.blocker_jump_target_id, s1.id)
+        else:
+            self.assertEqual(s2.blocker_kind, 'none')
+
+    def test_explicit_requires_predecessor_blocks(self):
+        s1 = self._make_step('Earlier', 10, state='ready')
+        s2 = self._make_step('Later', 20, state='ready')
+        s2.requires_predecessor_done = True
+        s2.invalidate_recordset(['blocker_kind', 'blocker_reason'])
+        self.assertEqual(s2.blocker_kind, 'predecessor')
+        self.assertEqual(s2.blocker_jump_target_id, s1.id)