feat(manual-batch): canonical plate + manual mode as default

- canonical_plate (uppercase alnum, strips space/dot/hyphen) at all plate
  write sites; pretty_plate for render (history, XLSX, operator tile) so
  B 1234 XYZ and B1234XYZ are one plate everywhere
- group_dos_by_plate compares canonical plates -> no false mixed_plates
- warn-only (never blocking) plate format hint in operator + monitoring modals
- batch.default_mode: manual (auto merged truck loads when a sack sat in the
  counting ROI); operator banner explains plate -> start -> stop
- docs + AGENTS known-limitation note; 85 tests pass

tests/test_config_loader.py

@@ -41,7 +41,7 @@ def test_repo_config_loads_and_validates(repo_config_path):
 
 def test_do_block_and_batch_default_mode(repo_config_path):
     cfg = load_config(repo_config_path)
-    assert cfg.batch.default_mode == "auto"
+    assert cfg.batch.default_mode == "manual"
     # timeout_seconds = sack-idle (pause); truck_gone_tolerance_seconds = finalize
     assert cfg.batch.timeout_seconds == 20.0
     assert cfg.batch.truck_gone_tolerance_seconds == 30.0

tests/test_do_batch.py

@@ -8,7 +8,9 @@ import pytest
 from src.do_batch import (
     BATCH_MODES,
     OCR_ENGINES,
+    canonical_plate,
     classify_unit_token,
+    pretty_plate,
     empty_do_settings,
     group_dos_by_plate,
     is_valid_batch_mode,
@@ -23,6 +25,35 @@ from src.do_batch import (
 from src.do_ocr import parse_fields_from_text
 
 
+def test_canonical_plate_strips_separators():
+    assert canonical_plate("  b 1234 xyz ") == "B1234XYZ"
+    assert canonical_plate("B-1234-XYZ") == "B1234XYZ"
+    assert canonical_plate("B.1234.XYZ") == "B1234XYZ"
+    assert canonical_plate("b1234xyz") == canonical_plate("B 1234 XYZ")
+    assert canonical_plate(None) == ""
+    assert canonical_plate("   ") == ""
+
+
+def test_pretty_plate_display_form():
+    assert pretty_plate("B1234XYZ") == "B 1234 XYZ"
+    assert pretty_plate("b 1234. xyz") == "B 1234 XYZ"
+    assert pretty_plate("B1") == "B 1"
+    assert pretty_plate("1234AB") == "1234 AB"
+    assert pretty_plate("") == ""
+    assert pretty_plate("!!") == "!!"  # not a plate pattern, raw fallback
+
+
+def test_group_dos_by_plate_ignores_spacing_only_difference():
+    dos = [
+        {"no_do": "D1", "plate": "B 1234 XYZ"},
+        {"no_do": "D2", "plate": "b1234xyz"},
+        {"no_do": "D3", "plate": "B-1234-XYZ"},
+    ]
+    plate, out = group_dos_by_plate(dos)
+    assert plate == "B1234XYZ"
+    assert all(d["plate"] == "B1234XYZ" for d in out)
+
+
 def test_normalize_batch_mode_defaults_auto():
     assert normalize_batch_mode(None) == "auto"
     assert normalize_batch_mode("bogus") == "auto"
@@ -59,7 +90,7 @@ def test_group_dos_same_plate():
         {"no_do": "DO-2", "plate": "B 1234 XYZ"},
     ]
     plate, out = group_dos_by_plate(dos)
-    assert plate == "B 1234 XYZ"
+    assert plate == "B1234XYZ"
     assert [d["no_do"] for d in out] == ["DO-1", "DO-2"]
 
 
@@ -293,10 +324,10 @@ def test_manual_start_with_plate_normalizes_and_persists(dash_client):
     assert res.status_code == 200
     body = res.get_json()
     assert body["success"] is True
-    assert body["plate"] == "B 1234 XYZ"
+    assert body["plate"] == "B1234XYZ"
     assert state_path.exists()
     state = json.loads(state_path.read_text())
-    assert state["plate"] == "B 1234 XYZ"
+    assert state["plate"] == "B1234XYZ"
     assert state["batch_mode"] == "manual"
     assert state["manual_control"] is True