web: DRY Step 5 and alternatives (partial+macro), centralize start_ctx/owned_set, adopt builder_*

code/tests/test_step5_error_ctx.py

@@ -0,0 +1,76 @@
+from __future__ import annotations
+
+from types import SimpleNamespace
+
+from code.web.services.build_utils import step5_error_ctx
+
+
+class _Req(SimpleNamespace):
+    # minimal object to satisfy template context needs
+    pass
+
+
+def test_step5_error_ctx_shape():
+    req = _Req()
+    sess = {
+        "commander": "Atraxa, Praetors' Voice",
+        "tags": ["+1/+1 Counters"],
+        "bracket": 3,
+        "ideals": {"lands": 36},
+        "use_owned_only": False,
+        "prefer_owned": False,
+        "replace_mode": True,
+        "locks": ["sol ring"],
+    }
+    ctx = step5_error_ctx(req, sess, "Boom")
+    # Ensure required keys for _step5.html are present with safe defaults
+    for k in (
+        "request",
+        "commander",
+        "tags",
+        "bracket",
+        "values",
+        "owned_only",
+        "prefer_owned",
+        "owned_set",
+        "game_changers",
+        "replace_mode",
+        "prefer_combos",
+        "combo_target_count",
+        "combo_balance",
+        "status",
+        "stage_label",
+        "log",
+        "added_cards",
+        "i",
+        "n",
+        "csv_path",
+        "txt_path",
+        "summary",
+        "show_skipped",
+        "total_cards",
+        "added_total",
+        "skipped",
+    ):
+        assert k in ctx
+    assert ctx["status"] == "Error"
+    assert isinstance(ctx["added_cards"], list)
+    assert ctx["show_skipped"] is False
+
+
+def test_step5_error_ctx_respects_flags():
+    req = _Req()
+    sess = {
+        "use_owned_only": True,
+        "prefer_owned": True,
+        "combo_target_count": 3,
+        "combo_balance": "early",
+    }
+    ctx = step5_error_ctx(req, sess, "Oops", include_name=False, include_locks=False)
+    assert "name" not in ctx
+    assert "locks" not in ctx
+    # Flags should flow through
+    assert ctx["owned_only"] is True
+    assert ctx["prefer_owned"] is True
+    assert ctx["combo_target_count"] == 3
+    assert ctx["combo_balance"] == "early"