feat(task-9): SECTION 22 - std_part_list, std_part_insert, std_feature_draw

engineering/mech/stdparts.py turns the Task 8 tables into real blocks. catalogue()
searches 83 transcribed parts by designation, standard, size or family;
block_spec() emits the typed primitives and DESIG/STD/SIZE/MAT ATTDEFs
block_define takes, in side/top for fasteners and ISO 8826-1 simplified /
ISO 8826-2 detailed for bearings; insert_std_part() defines the block once,
inserts it and writes the std_part ACADMCP_MECH payload the skeleton pins, so
the parts list is a read of the drawing rather than a naming convention.
Threads follow ISO 6410 - minor at 0.8 x major, a thread-length limit line to
the major, a three-quarter minor arc in the end view.

std_feature_draw() adds a thread, a DIN 509 undercut, a DIN 471/472 groove, a
DIN 332 centre hole or an ISO 3601-2 O-ring groove to geometry that already
exists. Its dimensions come from the shared standards registry, never from this
module: an absent table, a size outside coverage or a row missing a dimension is
refused by name, and the DIN 509 relief is drawn from the profile its table
publishes rather than reconstructed here. DIN 332 form R is refused outright.
An unknown designation is refused with the nearest catalogue entries; nothing is
drawn approximately.

SECTION 22 registers the three tools in the new mech pack, with alias records
(INSERT plus shop-floor synonyms in English and Turkish), a regenerated tool
inventory, the README release snapshot at 207 tools in 24 groups, and the frozen
group-size snapshot gaining mech: 3.

Two plan corrections, both verified by running the code:

* the plan's @cad_tool summaries for std_part_insert (118 chars) and
  std_feature_draw (130) overran discovery.serialize.MAX_SUMMARY_CHARS = 110, so
  tests/test_tool_registry.py::test_no_authored_summary_is_long_enough_to_be_truncated
  failed - they would have shipped rendered as "...". Both are shortened to 99
  and 104 characters with the same content.
* the plan's file list omitted tests/test_tool_packs.py, which pins the pack
  registry, the tool_packs report and the group count. It now carries MECH_TOOLS
  and distinguishes ALL_PACKS (declaration order, what "available" reports) from
  ALL_PACKS_ENABLED (sorted, what "enabled" reports) - those two lists stopped
  being the same list when "mech" was appended after "settings".

No new ActiveX member is called: the module drives block_list / block_define /
block_insert / entity_set_xdata / entity_create_* only. The COM path was still
executed live once on AutoCAD 2026 in a scratch document created and closed by
the probe: the bolt block defined with layers CENTER+GEOMETRY, attributes read
back as DESIG/STD/SIZE/MAT = ISO 4014 - M12x60 / ISO 4014 / M12x60 / 8.8, the
ACADMCP_MECH std_part payload round-tripped through entity_get_xdata,
STD_ISO_15_6205_SIMPLIFIED inserted, and the M20 thread's three primitives
landing on GEOMETRY.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd

tests/test_mech_std_features.py

@@ -0,0 +1,232 @@
+"""std_feature_draw: the ISO 6410 thread, and grooves drawn from registry rows.
+
+The DIN 471 / DIN 509 / DIN 332 / ISO 3601-2 tables themselves land with Task 3
+(group M). These tests register **synthetic** tables under obviously fake
+standard names, so what is pinned here is that the feature draws exactly the
+dimensions the registry publishes - never a number this module invented.
+"""
+
+from __future__ import annotations
+
+import math
+
+import pytest
+
+from engineering.mech.standards import Coverage, register, standards
+from engineering.mech.stdparts import (
+    STD_FEATURE_KINDS,
+    draw_std_feature,
+    feature_prims,
+    feature_spec,
+    place_prims,
+)
+
+
+@pytest.fixture(scope="module", autouse=True)
+def synthetic_tables():
+    """Round, obviously synthetic rows - NOT DIN or ISO values."""
+    if "TEST 471" in standards():
+        return
+    register(
+        "TEST 471",
+        {30.0: {"m": 2.0, "d2": 27.0}},
+        Coverage(8.0, 100.0),
+        "synthetic test fixture - the real DIN 471 table lands with Task 3",
+    )
+    register(
+        "TEST 472",
+        {30.0: {"m": 2.0, "d2": 33.0}},
+        Coverage(8.0, 100.0),
+        "synthetic test fixture - the real DIN 472 table lands with Task 3",
+    )
+    register(
+        "TEST 509",
+        {30.0: {"profile": [[0.0, 0.0], [0.0, 0.4], [2.0, 0.4], [2.5, 0.0]]}},
+        Coverage(18.0, 80.0),
+        "synthetic test fixture - the real DIN 509 table lands with Task 3",
+    )
+    register(
+        "TEST 332 A",
+        {2.5: {"d1": 2.5, "d2": 5.3, "t": 5.0}},
+        Coverage(1.0, 10.0),
+        "synthetic test fixture - the real DIN 332-1 table lands with Task 3",
+    )
+    register(
+        "TEST 332 B",
+        {2.5: {"d1": 2.5, "d2": 5.3, "d3": 6.3, "t": 6.0}},
+        Coverage(1.0, 10.0),
+        "synthetic test fixture - the real DIN 332-1 table lands with Task 3",
+    )
+    register(
+        "TEST 3601",
+        {3.53: {"b": 4.7, "h": 2.7}},
+        Coverage(1.0, 10.0),
+        "synthetic test fixture - the real ISO 3601-2 table lands with Task 3",
+    )
+
+
+def test_feature_kinds_are_the_five_the_spec_names():
+    assert STD_FEATURE_KINDS == (
+        "thread",
+        "undercut",
+        "ring_groove",
+        "centre_hole",
+        "oring_groove",
+    )
+    with pytest.raises(ValueError, match="oring_groove"):
+        feature_prims("spline", {})
+
+
+def test_external_thread_is_the_iso6410_representation():
+    spec = feature_spec("thread", {"d": 20.0, "length": 30.0, "size": "M20"})
+    assert spec["dims"]["pitch"] == 2.5  # ISO 261 coarse, from the fastener table
+    assert "ISO 6410" in spec["source"]
+    assert spec["prims"] == (
+        {"type": "line", "x1": 0.0, "y1": 8.0, "x2": 30.0, "y2": 8.0, "layer": "GEOMETRY"},
+        {"type": "line", "x1": 0.0, "y1": -8.0, "x2": 30.0, "y2": -8.0, "layer": "GEOMETRY"},
+        {"type": "line", "x1": 30.0, "y1": -10.0, "x2": 30.0, "y2": 10.0, "layer": "GEOMETRY"},
+    )
+
+
+def test_internal_thread_draws_the_major_diameter_instead():
+    prims = feature_prims("thread", {"d": 20.0, "length": 30.0, "pitch": 2.5, "internal": True})
+    assert prims[0]["y1"] == 10.0 and prims[1]["y1"] == -10.0
+
+
+def test_a_thread_without_a_size_or_a_pitch_is_refused():
+    with pytest.raises(ValueError, match="never guessed"):
+        feature_prims("thread", {"d": 20.0, "length": 30.0})
+    with pytest.raises(ValueError, match="ISO 261"):
+        feature_prims("thread", {"d": 14.0, "length": 30.0, "size": "M14"})
+
+
+def test_ring_groove_is_drawn_from_the_registry_row():
+    prims = feature_prims("ring_groove", {"d": 30.0, "kind": "shaft", "standard": "TEST 471"})
+    assert len(prims) == 6
+    assert prims[0] == {
+        "type": "line",
+        "x1": 0.0,
+        "y1": 15.0,
+        "x2": 0.0,
+        "y2": 13.5,
+        "layer": "GEOMETRY",
+    }
+    assert prims[1] == {
+        "type": "line",
+        "x1": 0.0,
+        "y1": 13.5,
+        "x2": 2.0,
+        "y2": 13.5,
+        "layer": "GEOMETRY",
+    }
+    assert prims[3]["y1"] == -15.0
+    bore = feature_prims("ring_groove", {"d": 30.0, "kind": "bore", "standard": "TEST 472"})
+    assert bore[1]["y1"] == 16.5
+
+
+def test_ring_groove_refuses_a_row_that_is_the_wrong_way_round():
+    with pytest.raises(ValueError, match="not a shaft groove"):
+        feature_prims("ring_groove", {"d": 30.0, "kind": "shaft", "standard": "TEST 472"})
+    with pytest.raises(ValueError, match="DIN 471"):
+        feature_prims("ring_groove", {"d": 30.0, "kind": "shaft"})
+
+
+def test_oring_groove_is_a_rectangular_groove_from_the_row():
+    prims = feature_prims(
+        "oring_groove", {"d": 30.0, "cord": 3.53, "kind": "shaft", "standard": "TEST 3601"}
+    )
+    assert len(prims) == 6
+    assert prims[0]["y1"] == 15.0 and prims[0]["y2"] == pytest.approx(12.3)
+    assert prims[1]["x2"] == pytest.approx(4.7)
+
+
+def test_centre_hole_form_a_is_a_sixty_degree_countersink():
+    spec = feature_spec("centre_hole", {"size": 2.5, "form": "A", "standard": "TEST 332 A"})
+    cone = math.sqrt(3.0) * (5.3 - 2.5) / 2.0
+    assert spec["dims"]["cone"] == pytest.approx(cone)
+    prims = spec["prims"]
+    assert len(prims) == 5
+    assert prims[0] == {
+        "type": "line",
+        "x1": 0.0,
+        "y1": 2.65,
+        "x2": pytest.approx(cone),
+        "y2": 1.25,
+        "layer": "GEOMETRY",
+    }
+    assert prims[2]["x2"] == 5.0 and prims[2]["y1"] == 1.25
+    assert prims[4] == {
+        "type": "line",
+        "x1": 5.0,
+        "y1": -1.25,
+        "x2": 5.0,
+        "y2": 1.25,
+        "layer": "GEOMETRY",
+    }
+
+
+def test_centre_hole_form_b_adds_the_protecting_chamfer():
+    prims = feature_prims("centre_hole", {"size": 2.5, "form": "B", "standard": "TEST 332 B"})
+    chamfer = (6.3 - 5.3) / (2.0 * math.sqrt(3.0))
+    assert len(prims) == 7
+    assert prims[0]["y1"] == 3.15  # d3 / 2
+    assert prims[0]["x2"] == pytest.approx(chamfer)
+
+
+def test_centre_hole_form_r_is_refused_not_approximated():
+    with pytest.raises(ValueError, match="forms A and B"):
+        feature_prims("centre_hole", {"size": 2.5, "form": "R", "standard": "TEST 332 A"})
+
+
+def test_undercut_draws_the_profile_the_table_publishes():
+    prims = feature_prims("undercut", {"d": 30.0, "form": "E", "standard": "TEST 509"})
+    assert len(prims) == 2
+    assert prims[0] == {
+        "type": "polyline",
+        "points": [[0.0, 15.0], [0.0, 14.6], [2.0, 14.6], [2.5, 15.0]],
+        "closed": False,
+        "layer": "GEOMETRY",
+    }
+    assert prims[1]["points"][1] == [0.0, -14.6]
+
+
+def test_undercut_refuses_a_row_without_a_profile():
+    with pytest.raises(ValueError, match="carries no profile"):
+        feature_prims("undercut", {"d": 30.0, "form": "E", "standard": "TEST 471"})
+    with pytest.raises(ValueError, match="DIN 509"):
+        feature_prims("undercut", {"d": 30.0, "form": "E"})
+
+
+def test_place_prims_rotates_about_the_insertion_point():
+    prims = feature_prims("thread", {"d": 20.0, "length": 30.0, "pitch": 2.5})
+    placed = place_prims(prims, (100.0, 50.0), 90.0)
+    assert placed[0]["x1"] == pytest.approx(92.0)
+    assert placed[0]["y1"] == pytest.approx(50.0)
+    assert placed[0]["x2"] == pytest.approx(92.0)
+    assert placed[0]["y2"] == pytest.approx(80.0)
+    with pytest.raises(ValueError, match="finite"):
+        place_prims(prims, (float("inf"), 0.0))
+
+
+@pytest.mark.asyncio
+async def test_draw_std_feature_writes_the_primitives(backend):
+    result = await draw_std_feature(
+        backend, "thread", (100.0, 50.0), {"d": 20.0, "length": 30.0, "size": "M20"}
+    )
+    assert result["ok"] is True
+    assert result["primitive_count"] == 3
+    assert len(result["handles"]) == 3
+    assert result["layers"] == ["GEOMETRY"]
+    assert result["dims"]["pitch"] == 2.5
+    info = await backend.entity_get(result["handles"][0])
+    assert info.layer == "GEOMETRY"
+
+
+@pytest.mark.asyncio
+async def test_draw_std_feature_refuses_before_writing_anything(backend):
+    before = len(await backend.entity_list())
+    with pytest.raises(ValueError, match="never guessed"):
+        await draw_std_feature(backend, "thread", (0.0, 0.0), {"d": 20.0, "length": 30.0})
+    with pytest.raises(ValueError, match="DIN 509"):
+        await draw_std_feature(backend, "undercut", (0.0, 0.0), {"d": 30.0})
+    assert len(await backend.entity_list()) == before

tests/test_mech_stdparts.py

@@ -0,0 +1,333 @@
+"""The standard-parts catalogue: search, designations, block specs, insertion.
+
+Geometry is asserted as emitted primitive dicts - counts, layers, coordinates -
+never as a screenshot.
+"""
+
+from __future__ import annotations
+
+import math
+
+import pytest
+
+from backends.block_specs import validate_attdef_specs, validate_entity_specs
+from engineering.mech.stdparts import (
+    FAMILY_STANDARDS,
+    FAMILY_VIEWS,
+    THREAD_MINOR_RATIO,
+    block_spec,
+    catalogue,
+    parse_designation,
+)
+
+R12 = 2.0 * 18.0 / math.sqrt(3.0) / 2.0  # across-corners radius of an M12 hex head
+MINOR12 = THREAD_MINOR_RATIO * 12.0 / 2.0  # ISO 6410 minor radius of an M12 thread
+
+
+def test_the_iso6410_minor_radius_is_four_point_eight():
+    """Pinned as the builder computes it: 0.8 * 12 / 2 is 4.800000000000001 in binary."""
+    assert MINOR12 == pytest.approx(4.8)
+
+
+def test_the_catalogue_holds_every_transcribed_size():
+    rows = catalogue()
+    assert len(rows) == 83  # 5 fastener standards x 10 sizes + 33 bearings
+    assert len(catalogue(standard="ISO 15")) == 33
+    assert len(catalogue("M12")) == 5
+    assert len(catalogue("6205")) == 1
+    assert {row["standard"] for row in rows} == set(FAMILY_STANDARDS)
+
+
+def test_a_catalogue_row_carries_what_a_drawing_needs():
+    (row,) = catalogue("6205")
+    assert row["designation"] == "ISO 15 - 6205"
+    assert row["standard"] == "ISO 15"
+    assert row["family"] == "deep_groove_bearing"
+    assert row["views"] == ["simplified", "detailed"]
+    assert row["length_required"] is False
+    assert row["dims"] == {"d": 25.0, "D": 52.0, "B": 15.0}
+    assert "ISO 15:2017" in row["source"]
+
+    bolt = next(r for r in catalogue(standard="ISO 4014") if r["size"] == "M12")
+    assert bolt["length_required"] is True
+    assert bolt["dims"]["s"] == 18.0 and bolt["dims"]["k"] == 7.5
+
+
+def test_catalogue_refuses_an_unknown_standard():
+    with pytest.raises(ValueError, match="ISO 4014"):
+        catalogue(standard="DIN 931")
+
+
+def test_parse_designation_normalises_and_splits():
+    assert parse_designation("iso4014 - m12x60") == {
+        "designation": "ISO 4014 - M12x60",
+        "standard": "ISO 4014",
+        "family": "hex_bolt",
+        "size": "M12x60",
+        "thread": "M12",
+        "length": 60.0,
+    }
+    assert parse_designation("6205")["designation"] == "ISO 15 - 6205"
+    assert parse_designation("ISO 4032 - M12")["length"] is None
+
+
+def test_parse_designation_refuses_a_missing_or_stray_length():
+    with pytest.raises(ValueError, match="nominal length"):
+        parse_designation("ISO 4014 - M12")
+    with pytest.raises(ValueError, match="takes no length"):
+        parse_designation("ISO 4032 - M12x60")
+    with pytest.raises(ValueError, match="catalogue standard"):
+        parse_designation("ISO 9999 - M12")
+
+
+def test_an_unknown_size_is_refused_with_the_nearest_entries():
+    with pytest.raises(ValueError, match=r"ISO 4014 - M12"):
+        block_spec("ISO 4014 - M13x60", "side")
+    with pytest.raises(ValueError, match=r"ISO 15 - 6210"):
+        block_spec("ISO 15 - 6211", "simplified")
+    with pytest.raises(ValueError, match="approximately"):
+        block_spec("ISO 4014 - M13x60", "side")
+
+
+def test_hex_bolt_side_view_is_the_iso6410_representation():
+    spec = block_spec("ISO 4014 - M12x60", "side")
+    assert spec["name"] == "STD_ISO_4014_M12X60_SIDE"
+    assert spec["view"] == "side"
+    assert spec["dims"]["b"] == pytest.approx(30.0)  # 2d + 6 for l <= 125
+    ents = spec["entities"]
+    assert len(ents) == 10
+    assert ents[0]["type"] == "polyline" and ents[0]["closed"] is True
+    assert ents[0]["points"] == [
+        [-7.5, -R12],
+        [0.0, -R12],
+        [0.0, R12],
+        [-7.5, R12],
+    ]
+    assert ents[3] == {
+        "type": "line",
+        "x1": 0.0,
+        "y1": 6.0,
+        "x2": 60.0,
+        "y2": 6.0,
+        "layer": "GEOMETRY",
+    }
+    # ISO 6410: minor diameter at 0.8 x major, over the useful thread length.
+    assert ents[6] == {
+        "type": "line",
+        "x1": 30.0,
+        "y1": MINOR12,
+        "x2": 60.0,
+        "y2": MINOR12,
+        "layer": "GEOMETRY",
+    }
+    # ISO 6410: the thread-length limit is a line to the major diameter.
+    assert ents[8] == {
+        "type": "line",
+        "x1": 30.0,
+        "y1": -6.0,
+        "x2": 30.0,
+        "y2": 6.0,
+        "layer": "GEOMETRY",
+    }
+    assert ents[9]["layer"] == "CENTER"
+    assert spec["bbox"] == pytest.approx((-10.5, -R12, 63.0, R12))
+
+
+def test_a_fully_threaded_screw_has_no_thread_limit_line():
+    spec = block_spec("ISO 4017 - M12x60", "side")
+    assert len(spec["entities"]) == 9
+    assert spec["dims"]["b"] == pytest.approx(60.0)
+    minor = [e for e in spec["entities"] if e.get("y1") == MINOR12]
+    assert minor[0]["x1"] == 0.0 and minor[0]["x2"] == 60.0
+
+
+def test_hex_top_view_uses_the_three_quarter_minor_arc():
+    spec = block_spec("ISO 4014 - M12x60", "top")
+    ents = spec["entities"]
+    assert len(ents) == 5
+    assert ents[0]["type"] == "polyline" and len(ents[0]["points"]) == 6
+    assert ents[1] == {"type": "circle", "cx": 0.0, "cy": 0.0, "r": 6.0, "layer": "GEOMETRY"}
+    assert ents[2] == {
+        "type": "arc",
+        "cx": 0.0,
+        "cy": 0.0,
+        "r": MINOR12,
+        "start_deg": 90.0,
+        "end_deg": 360.0,
+        "layer": "GEOMETRY",
+    }
+    assert ents[3]["layer"] == "CENTER" and ents[4]["layer"] == "CENTER"
+
+
+def test_hex_nut_side_view_shows_the_thread_as_hidden_lines():
+    spec = block_spec("ISO 4032 - M12", "side")
+    ents = spec["entities"]
+    assert len(ents) == 8
+    hidden = [e for e in ents if e["layer"] == "HIDDEN"]
+    assert len(hidden) == 4
+    assert {abs(e["y1"]) for e in hidden} == {6.0, MINOR12}
+    assert ents[0]["points"][1] == [10.8, -R12]  # nut height m
+
+
+def test_washer_views():
+    side = block_spec("ISO 7089 - M12", "side")
+    assert len(side["entities"]) == 3
+    assert side["entities"][0]["points"] == [[0.0, 6.5], [2.5, 6.5], [2.5, 12.0], [0.0, 12.0]]
+    top = block_spec("ISO 7089 - M12", "top")
+    assert top["entities"][0] == {
+        "type": "circle",
+        "cx": 0.0,
+        "cy": 0.0,
+        "r": 12.0,
+        "layer": "GEOMETRY",
+    }
+    assert top["entities"][1]["r"] == 6.5
+
+
+def test_socket_head_screw_views():
+    side = block_spec("ISO 4762 - M8x30", "side")
+    assert len(side["entities"]) == 8
+    assert side["dims"]["b"] == pytest.approx(28.0)
+    assert side["entities"][0]["points"][0] == [-8.0, -6.5]  # k = 8, dk/2 = 6.5
+    top = block_spec("ISO 4762 - M8x30", "top")
+    assert top["entities"][0]["r"] == 6.5
+    assert len(top["entities"][1]["points"]) == 6  # the hexagon socket, s = 6
+
+
+def test_bearing_simplified_is_the_iso8826_1_outline_and_cross():
+    spec = block_spec("ISO 15 - 6205", "simplified")
+    ents = spec["entities"]
+    assert len(ents) == 7
+    assert ents[0]["points"] == [[-7.5, 12.5], [7.5, 12.5], [7.5, 26.0], [-7.5, 26.0]]
+    assert ents[1]["points"] == [[-7.5, -12.5], [7.5, -12.5], [7.5, -26.0], [-7.5, -26.0]]
+    assert ents[2] == {
+        "type": "line",
+        "x1": -4.5,
+        "y1": 19.25,
+        "x2": 4.5,
+        "y2": 19.25,
+        "layer": "GEOMETRY",
+    }
+    assert ents[3] == {
+        "type": "line",
+        "x1": 0.0,
+        "y1": 15.2,
+        "x2": 0.0,
+        "y2": 23.3,
+        "layer": "GEOMETRY",
+    }
+    assert ents[6]["layer"] == "CENTER"
+
+
+def test_bearing_detailed_draws_the_element_symbol():
+    spec = block_spec("ISO 15 - 6205", "detailed")
+    ents = spec["entities"]
+    assert len(ents) == 5
+    assert ents[2] == {
+        "type": "circle",
+        "cx": 0.0,
+        "cy": 19.25,
+        "r": 4.05,
+        "layer": "GEOMETRY",
+    }
+    assert ents[3]["cy"] == -19.25
+
+
+def test_a_view_the_family_does_not_have_is_refused_and_side_falls_back():
+    assert block_spec("ISO 15 - 6205", "side")["view"] == "simplified"
+    with pytest.raises(ValueError, match="simplified"):
+        block_spec("ISO 15 - 6205", "top")
+    with pytest.raises(ValueError, match="side"):
+        block_spec("ISO 4014 - M12x60", "simplified")
+
+
+@pytest.mark.parametrize(
+    ("designation", "view"),
+    [
+        ("ISO 4014 - M12x60", "side"),
+        ("ISO 4014 - M12x60", "top"),
+        ("ISO 4017 - M12x60", "side"),
+        ("ISO 4032 - M12", "side"),
+        ("ISO 4032 - M12", "top"),
+        ("ISO 7089 - M12", "side"),
+        ("ISO 7089 - M12", "top"),
+        ("ISO 4762 - M8x30", "side"),
+        ("ISO 4762 - M8x30", "top"),
+        ("ISO 15 - 6205", "simplified"),
+        ("ISO 15 - 6205", "detailed"),
+    ],
+)
+def test_every_block_spec_validates_against_block_define(designation, view):
+    spec = block_spec(designation, view)
+    validate_entity_specs(spec["entities"])
+    validate_attdef_specs(spec["attdefs"])
+    assert [att["tag"] for att in spec["attdefs"]] == ["DESIG", "STD", "SIZE", "MAT"]
+    assert spec["attdefs"][0]["default"] == spec["designation"]
+    assert spec["attdefs"][0]["invisible"] is False
+    assert all(att["invisible"] for att in spec["attdefs"][1:])
+    assert spec["bbox"][0] < spec["bbox"][2] and spec["bbox"][1] < spec["bbox"][3]
+    assert set(FAMILY_VIEWS[spec["family"]]) >= {spec["view"]}
+
+
+@pytest.mark.asyncio
+async def test_insert_defines_the_block_once_and_writes_the_payload(backend):
+    from engineering.mech.stdparts import insert_std_part
+    from engineering.mech.xdata import APP_ID, decode
+
+    result = await insert_std_part(backend, "ISO 4014 - M12x60", at=(100.0, 50.0), material="8.8")
+    assert result["ok"] is True
+    assert result["block_name"] == "STD_ISO_4014_M12X60_SIDE"
+    assert result["defined"] is True
+    assert sorted(result["layers_created"]) == ["CENTER", "GEOMETRY"]
+    assert result["view"] == "side"
+    assert result["layer"] == "GEOMETRY"
+    assert result["dims"]["s"] == 18.0
+
+    stored = await backend.entity_get_xdata(result["handle"], APP_ID)
+    payload = decode([(1001, APP_ID)] + [(1000, value) for value in stored["xdata"][APP_ID]])
+    assert payload == {
+        "v": 1,
+        "kind": "std_part",
+        "designation": "ISO 4014 - M12x60",
+        "standard": "ISO 4014",
+        "size": "M12x60",
+        "qty": 1,
+        "material": "8.8",
+    }
+    assert await backend.block_get_attributes(result["handle"]) == {
+        "DESIG": "ISO 4014 - M12x60",
+        "STD": "ISO 4014",
+        "SIZE": "M12x60",
+        "MAT": "8.8",
+    }
+
+    again = await insert_std_part(backend, "ISO 4014 - M12x60", at=(200.0, 50.0))
+    assert again["defined"] is False and again["layers_created"] == []
+    assert again["payload"]["material"] == ""
+
+
+@pytest.mark.asyncio
+async def test_bearing_inserts_with_its_own_view_name(backend):
+    from engineering.mech.stdparts import insert_std_part
+
+    result = await insert_std_part(backend, "6205", at=(0.0, 0.0), rotation=90.0)
+    assert result["block_name"] == "STD_ISO_15_6205_SIMPLIFIED"
+    assert result["view"] == "simplified"
+    assert result["rotation"] == 90.0
+    assert result["dims"]["B"] == 15.0
+
+
+@pytest.mark.asyncio
+async def test_insert_refuses_before_writing_anything(backend):
+    from engineering.mech.stdparts import insert_std_part
+
+    before = len(await backend.entity_list())
+    with pytest.raises(ValueError, match="Nearest entries"):
+        await insert_std_part(backend, "ISO 4014 - M13x60", at=(0.0, 0.0))
+    with pytest.raises(ValueError, match="finite"):
+        await insert_std_part(backend, "ISO 4014 - M12x60", at=(float("nan"), 0.0))
+    with pytest.raises(ValueError, match="no attribute"):
+        await insert_std_part(
+            backend, "ISO 4014 - M12x60", at=(0.0, 0.0), attributes={"TORQUE": "80"}
+        )
+    assert len(await backend.entity_list()) == before

tests/test_tool_packs.py

@@ -5,6 +5,8 @@ v1.6 track E adds the `settings` pack: the 22 SECTION 20 environment tools.
 Styles (SECTION 18) and page setup / templates (SECTION 19) are drafting
 essentials and stay in `core`, so `TOOL_PACKS=core` hides the environment
 surface and nothing else.
+
+v1.6 tracks B+G add the `mech` pack: SECTION 22's three standard-parts tools.
 """
 
 from __future__ import annotations
@@ -78,6 +80,12 @@ SETTINGS_TOOLS = {
     "system_prompt_message",
 }
 
+MECH_TOOLS = {
+    "std_part_list",
+    "std_part_insert",
+    "std_feature_draw",
+}
+
 LEAN_SETTINGS_ESSENTIALS = {
     "drawing_apply_standard",
     "page_setup_apply",
@@ -86,7 +94,10 @@ LEAN_SETTINGS_ESSENTIALS = {
     "textstyle_set_current",
 }
 
-ALL_PACKS = ["core", "pid", "settings"]
+#: Declaration order - what `tool_packs["available"]` reports.
+ALL_PACKS = ["core", "pid", "settings", "mech"]
+#: `tool_packs["enabled"]` is sorted, which is no longer the same list.
+ALL_PACKS_ENABLED = sorted(ALL_PACKS)
 
 
 @pytest_asyncio.fixture(autouse=True)
@@ -97,11 +108,15 @@ async def _restore(monkeypatch):
 
 
 def test_pack_registry_names_real_tools_and_only_them():
-    assert server.TOOL_PACK_NAMES == ("core", "pid", "settings")
+    assert server.TOOL_PACK_NAMES == ("core", "pid", "settings", "mech")
     assert server.PACK_TOOL_NAMES["pid"] == frozenset(PID_TOOLS)
     assert server.PACK_TOOL_NAMES["settings"] == frozenset(SETTINGS_TOOLS)
+    assert server.PACK_TOOL_NAMES["mech"] == frozenset(MECH_TOOLS)
     assert len(SETTINGS_TOOLS) == 22
+    assert len(MECH_TOOLS) == 3
     assert not (server.PACK_TOOL_NAMES["settings"] & server.PACK_TOOL_NAMES["pid"])
+    assert not (server.PACK_TOOL_NAMES["mech"] & server.PACK_TOOL_NAMES["pid"])
+    assert not (server.PACK_TOOL_NAMES["mech"] & server.PACK_TOOL_NAMES["settings"])
 
 
 async def test_every_pack_member_is_a_registered_tool():
@@ -117,6 +132,7 @@ async def test_core_only_hides_pid_and_settings_but_keeps_styles_and_page_setup(
     disabled = set(info["disabled_tools"])
     assert PID_TOOLS <= disabled
     assert SETTINGS_TOOLS <= disabled
+    assert MECH_TOOLS <= disabled
     assert not (STYLE_TOOLS & disabled), "styles are core drafting essentials"
     assert not (PAGE_SETUP_TOOLS & disabled), "page setup and templates are core"
     assert "block_define" not in disabled and "entity_set_xdata" not in disabled
@@ -136,8 +152,8 @@ async def test_all_is_the_default_and_enables_every_pack(monkeypatch):
     monkeypatch.setattr(config.settings, "tool_packs", "all")
     info = await server._apply_tool_profile("full")
     disabled = set(info["disabled_tools"])
-    assert not ((PID_TOOLS | SETTINGS_TOOLS) & disabled)
-    assert info["tool_packs"]["enabled"] == ALL_PACKS
+    assert not ((PID_TOOLS | SETTINGS_TOOLS | MECH_TOOLS) & disabled)
+    assert info["tool_packs"]["enabled"] == ALL_PACKS_ENABLED
 
 
 async def test_unknown_pack_is_ignored_with_a_warning_and_core_cannot_be_dropped(
@@ -184,7 +200,8 @@ async def test_the_three_track_e_sections_file_under_their_own_groups():
     assert set(groups["styles"]) == STYLE_TOOLS
     assert set(groups["page_setup"]) == PAGE_SETUP_TOOLS
     assert set(groups["environment"]) == SETTINGS_TOOLS
-    assert len(groups) == 23
+    assert set(groups["mech"]) == MECH_TOOLS
+    assert len(groups) == 24
 
 
 async def test_system_about_reports_packs():

tests/test_tool_registry.py

@@ -529,6 +529,13 @@ async def test_tool_group_sizes_are_unchanged():
     their secondary tags; those counts returned to their pre-track-E values
     when the section tags landed.) Every other number here has been unchanged
     since the snapshot was taken.
+
+    `mech` appeared (0 -> 3) when v1.6's SECTION 22 opened with the
+    standard-parts catalogue (`std_part_list` / `std_part_insert` /
+    `std_feature_draw`); the `mech` tag is ranked directly after `pid` in
+    `_GROUP_TAG_PRIORITY`, so those tools file under `mech` rather than under
+    their secondary `query` / `create` tags. This snapshot is branch-local:
+    the merge task recomputes it once all four track B+G branches have landed.
     """
     sizes = {label: len(names) for label, names in (await server._tool_groups()).items()}
     assert sizes == {
@@ -545,6 +552,7 @@ async def test_tool_group_sizes_are_unchanged():
         "environment": 22,
         "layers": 14,
         "layouts": 12,
+        "mech": 3,
         "page_setup": 6,
         "pid": 9,
         "premium": 12,
@@ -556,4 +564,4 @@ async def test_tool_group_sizes_are_unchanged():
         "validation": 1,
         "view": 4,
     }
-    assert sum(sizes.values()) == 204
+    assert sum(sizes.values()) == 207