feat(harness): Workflow.schema_linking_phase() (Onda 1.1, TDD)

Aggiunge il metodo che i cmd CLI useranno al posto della vecchia costante
SCHEMA_LINKING_PHASE (drift fix Onda 1). Ritorna il num della fase il cui
artifacts_out contiene schema_linking.json, default 5 se nessuna la dichiara.

L1: 4 test (fase reale F4, posizione arbitraria, default 5, artefatti multipli).
Suite: 157 passed.

harness/tests/test_workflow_schema_linking_phase.py

@@ -0,0 +1,53 @@
+"""L1: Workflow.schema_linking_phase() — the phase that produces schema_linking.json.
+
+Used by the CLI drift fix (the old SCHEMA_LINKING_PHASE constant is gone; commands
+now ask the Workflow for it). Returns the num of the phase whose artifacts_out
+contains schema_linking.json, defaulting to 5 if no phase declares it.
+"""
+from tht.workflow import PhaseSpec, Workflow
+
+
+def _wf(phases: list[PhaseSpec]) -> Workflow:
+    return Workflow(schema_version=1, phases=phases, _decision_min_map={})
+
+
+def test_schema_linking_phase_returns_num_of_phase_with_artifact():
+    # the real workflow: F4 schema_linking produces schema_linking.json
+    from tht.workflow import load_workflow
+
+    wf = load_workflow()
+    assert wf.schema_linking_phase() == 4
+
+
+def test_schema_linking_phase_finds_it_wherever_it_is():
+    # synthetic: schema_linking.json declared on phase 3
+    phases = [
+        PhaseSpec(id="F1", num=1, name="a", advance="kind:phase", prerequisites=[]),
+        PhaseSpec(id="F2", num=2, name="b", advance="kind:phase", prerequisites=[]),
+        PhaseSpec(
+            id="F3", num=3, name="c", advance="kind:phase",
+            prerequisites=[], artifacts_out=["schema_linking.json"],
+        ),
+    ]
+    assert _wf(phases).schema_linking_phase() == 3
+
+
+def test_schema_linking_phase_defaults_to_5_when_no_artifact_declared():
+    # defensive: if no phase declares schema_linking.json, fall back to 5 (the
+    # conventional schema-linking phase) rather than raising.
+    phases = [
+        PhaseSpec(id="F1", num=1, name="a", advance="kind:phase", prerequisites=[]),
+        PhaseSpec(id="F2", num=2, name="b", advance="kind:phase", prerequisites=[]),
+    ]
+    assert _wf(phases).schema_linking_phase() == 5
+
+
+def test_schema_linking_phase_with_multiple_artifacts_finds_the_right_one():
+    # a phase can produce multiple artifacts; schema_linking.json among them
+    phases = [
+        PhaseSpec(
+            id="F5", num=5, name="sintesi", advance="kind:phase",
+            prerequisites=[], artifacts_out=["cte_plan.json", "schema_linking.json"],
+        ),
+    ]
+    assert _wf(phases).schema_linking_phase() == 5

harness/tht/workflow.py

@@ -50,6 +50,15 @@ class Workflow:
         reference it (via decision_exists / decision_subject_exists). Defaults to 1."""
         return self._decision_min_map.get(decision_type, 1)
 
+    def schema_linking_phase(self) -> int:
+        """The phase that produces schema_linking.json (artifacts_out). Default 5
+        (the conventional schema-linking phase) if no phase declares it. Used by the
+        CLI drift fix in place of the old SCHEMA_LINKING_PHASE constant."""
+        for p in self.phases:
+            if "schema_linking.json" in p.artifacts_out:
+                return p.num
+        return 5
+
 
 def _collect_decision_mins(phases: list[PhaseSpec]) -> dict[str, int]:
     """Scan prerequisites for decision_exists / decision_subject_exists mentions.