feat(standards): ISO-25 and ANSI dimension, text and leader style presets as pinned data

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

engineering/standards/__init__.py

@@ -0,0 +1,39 @@
+"""Authored drafting standards data.
+
+Dimension, text and leader style presets live here (track E, group S); the
+system-variable catalogue, paper sizes, plot styles and templates are sibling
+modules added by their own groups and imported by path. Everything in this
+package is data plus validation — no I/O, no ezdxf, no COM — so the backends,
+the tools and the provenance tests read one copy.
+"""
+
+from __future__ import annotations
+
+from engineering.standards.dimstyles import (
+    DIM_VARIABLE_RANGES,
+    DIM_VARIABLE_WHITELIST,
+    PRESET_VARIABLES,
+    PRESETS,
+    check_dim_value,
+    describe_preset,
+    resolve_dimstyle,
+    validate_overrides,
+)
+from engineering.standards.mleaderstyles import MLEADER_PRESETS, resolve_mleaderstyle
+from engineering.standards.textstyles import TEXT_PRESETS, resolve_font, validate_textstyle
+
+__all__ = [
+    "DIM_VARIABLE_RANGES",
+    "DIM_VARIABLE_WHITELIST",
+    "MLEADER_PRESETS",
+    "PRESETS",
+    "PRESET_VARIABLES",
+    "TEXT_PRESETS",
+    "check_dim_value",
+    "describe_preset",
+    "resolve_dimstyle",
+    "resolve_font",
+    "resolve_mleaderstyle",
+    "validate_overrides",
+    "validate_textstyle",
+]

engineering/standards/dimstyles.py

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+"""ISO-25 and ANSI dimension style presets as data.
+
+Every value in ``PRESETS`` is pinned by name in
+``tests/test_standards_presets.py`` against the table in §4.1 of
+``docs/superpowers/specs/2026-09-16-v1.6-settings-design.md``:
+
+* ``iso-25`` — ISO 129-1:2018 dimensioning at the 2.5 mm lettering row of
+  ISO 3098-1: 2.5 mm text and arrowheads, text above and aligned with the
+  dimension line, decimal comma (ISO 80000-1 allows either marker; AutoCAD's
+  own ISO-25 uses the comma).
+* ``ansi`` — ASME Y14.2-2014 line conventions and lettering (3 mm / .12 in
+  lettering, .125 in arrowheads) in metric values: 3 mm text and arrowheads,
+  text centred in a gap and horizontal, decimal point.
+
+``DIMDSEP`` is a one-character *string* here. DXF stores the character code and
+ezdxf raises on a string in the header, so the translation belongs to the
+backends, not to the data.
+
+Pure data plus validation: no I/O, no ezdxf, no COM, so the backends, the
+tools and the provenance tests all read one copy.
+"""
+
+from __future__ import annotations
+
+import math
+from typing import Any
+
+__all__ = [
+    "ANSI",
+    "DIM_VARIABLE_RANGES",
+    "DIM_VARIABLE_WHITELIST",
+    "ISO_25",
+    "LINEWEIGHT_CODES",
+    "PRESETS",
+    "PRESET_SOURCES",
+    "PRESET_VARIABLES",
+    "check_dim_value",
+    "describe_preset",
+    "resolve_dimstyle",
+    "validate_overrides",
+]
+
+#: The seventeen variables every preset sets, in the order the spec table
+#: lists them. ``dimstyle_list`` reports exactly these.
+PRESET_VARIABLES: tuple[str, ...] = (
+    "DIMTXT",
+    "DIMASZ",
+    "DIMEXE",
+    "DIMEXO",
+    "DIMGAP",
+    "DIMTAD",
+    "DIMTIH",
+    "DIMTOH",
+    "DIMDEC",
+    "DIMDSEP",
+    "DIMLUNIT",
+    "DIMZIN",
+    "DIMBLK",
+    "DIMTXSTY",
+    "DIMLWD",
+    "DIMLWE",
+    "DIMSCALE",
+)
+
+ISO_25: dict[str, Any] = {
+    "DIMTXT": 2.5,  # text height, mm — ISO 3098-1 lettering row 2.5
+    "DIMASZ": 2.5,  # arrowhead length, matched to the text
+    "DIMEXE": 1.25,  # extension line beyond the dimension line
+    "DIMEXO": 0.625,  # extension line offset from the feature
+    "DIMGAP": 0.625,  # gap between dimension line and text
+    "DIMTAD": 1,  # text above the dimension line
+    "DIMTIH": 0,  # inside text aligned with the dimension line
+    "DIMTOH": 0,  # outside text aligned with the dimension line
+    "DIMDEC": 2,  # linear decimals
+    "DIMDSEP": ",",  # decimal comma
+    "DIMLUNIT": 2,  # decimal linear units
+    "DIMZIN": 8,  # trailing zeros suppressed
+    "DIMBLK": "",  # closed filled arrowhead
+    "DIMTXSTY": "ISOCP",  # ISO 3098 type B lettering (created if missing)
+    "DIMLWD": -2,  # dimension line lineweight ByBlock
+    "DIMLWE": -2,  # extension line lineweight ByBlock
+    "DIMSCALE": 1.0,
+}
+
+ANSI: dict[str, Any] = {
+    "DIMTXT": 3.0,  # 3 mm / .12 in lettering, ASME Y14.2-2014
+    "DIMASZ": 3.0,  # .125 in arrowheads, metric
+    "DIMEXE": 1.5,
+    "DIMEXO": 1.5,
+    "DIMGAP": 1.0,
+    "DIMTAD": 0,  # text centred in a gap in the dimension line
+    "DIMTIH": 1,  # inside text horizontal
+    "DIMTOH": 1,  # outside text horizontal
+    "DIMDEC": 2,
+    "DIMDSEP": ".",  # decimal point
+    "DIMLUNIT": 2,
+    "DIMZIN": 8,
+    "DIMBLK": "",
+    "DIMTXSTY": "ROMANS",  # AutoCAD's simplex roman, the ASME Gothic look
+    "DIMLWD": -2,
+    "DIMLWE": -2,
+    "DIMSCALE": 1.0,
+}
+
+PRESETS: dict[str, dict[str, Any]] = {"iso-25": ISO_25, "ansi": ANSI}
+
+PRESET_SOURCES: dict[str, str] = {
+    "iso-25": (
+        "ISO 129-1:2018 (dimensioning) with the 2.5 mm lettering row of "
+        "ISO 3098-1 (text and arrow sizes); decimal comma per ISO 80000-1"
+    ),
+    "ansi": (
+        "ASME Y14.2-2014 line conventions and lettering: 3 mm / .12 in lettering, "
+        ".125 in arrowheads, metric values"
+    ),
+}
+
+#: The lineweights AutoCAD accepts, in hundredths of a millimetre, plus the
+#: ByLayer / ByBlock / Default sentinels. Every ISO 128 weight is in here.
+_LINEWEIGHT_TEXT = (
+    "-3 -2 -1 0 5 9 13 15 18 20 25 30 35 40 50 53 60 70 80 90 100 106 120 140 158 200 211"
+)
+LINEWEIGHT_CODES: frozenset[int] = frozenset(int(code) for code in _LINEWEIGHT_TEXT.split())
+
+#: What ``dimstyle_create`` / ``dimstyle_modify`` will write, and the range each
+#: value must sit in. The shape of each entry:
+#:
+#: * ``("float", low, high)`` — a number (bool refused) within the inclusive
+#:   bounds; a ``low`` of ``1e-9`` is the repo's spelling of "strictly positive"
+#:   (``backends/contracts/settings.py::_SETTING_RANGES``).
+#: * ``("int", low, high)`` — an integer (a float with no fraction is accepted).
+#: * ``("nonzero_float", low, high)`` — as ``float`` but ``0`` is refused.
+#: * ``("char",)`` — exactly one character.
+#: * ``("str",)`` — any string (arrowhead block names; ``""`` is the closed filled arrow).
+#: * ``("name",)`` — a non-empty DXF symbol-table name.
+#: * a ``set`` — one of its members.
+DIM_VARIABLE_RANGES: dict[str, tuple | set] = {
+    # the seventeen the presets set
+    "DIMTXT": ("float", 1e-9, 1e6),
+    "DIMASZ": ("float", 1e-9, 1e6),
+    "DIMEXE": ("float", 0.0, 1e6),
+    "DIMEXO": ("float", 0.0, 1e6),
+    "DIMGAP": ("float", -1e6, 1e6),  # negative draws the basic-dimension box
+    "DIMTAD": ("int", 0, 4),
+    "DIMTIH": {0, 1},
+    "DIMTOH": {0, 1},
+    "DIMDEC": ("int", 0, 8),
+    "DIMDSEP": ("char",),
+    "DIMLUNIT": ("int", 1, 6),
+    "DIMZIN": ("int", 0, 15),  # a bitmask
+    "DIMBLK": ("str",),
+    "DIMTXSTY": ("name",),
+    "DIMLWD": LINEWEIGHT_CODES,
+    "DIMLWE": LINEWEIGHT_CODES,
+    "DIMSCALE": ("float", 0.0, 1e6),  # 0 means "scale to the viewport"
+    # tolerances, rounding, fit, colours, arrowheads — the rest of the whitelist
+    "DIMTOL": {0, 1},
+    "DIMTP": ("float", 0.0, 1e6),
+    "DIMTM": ("float", 0.0, 1e6),
+    "DIMTOLJ": ("int", 0, 2),
+    "DIMTFAC": ("float", 1e-9, 1e6),
+    "DIMLFAC": ("nonzero_float", -1e6, 1e6),
+    "DIMRND": ("float", 0.0, 1e6),  # 0 = no rounding; the backends discard it, never store it
+    "DIMATFIT": ("int", 0, 3),
+    "DIMTMOVE": ("int", 0, 2),
+    "DIMCLRD": ("int", 0, 256),
+    "DIMCLRE": ("int", 0, 256),
+    "DIMCLRT": ("int", 0, 256),
+    "DIMSAH": {0, 1},
+    "DIMBLK1": ("str",),
+    "DIMBLK2": ("str",),
+    "DIMCEN": ("float", -1e6, 1e6),  # negative draws centre lines, 0 none
+}
+
+DIM_VARIABLE_WHITELIST: frozenset[str] = frozenset(DIM_VARIABLE_RANGES)
+
+#: DXF forbids these in a symbol-table name; the same rule ``security.py``
+#: applies to block and layer names, restated here so this module stays free
+#: of fastmcp.
+_ILLEGAL_NAME_CHARS = frozenset('<>/\\":;?*|,=`')
+
+
+def _number(key: str, value: Any) -> float:
+    if isinstance(value, bool) or not isinstance(value, (int, float)):
+        raise TypeError(f"{key}: expected a number, got {type(value).__name__}")
+    number = float(value)
+    if not math.isfinite(number):
+        raise ValueError(f"{key}: {value!r} is not a finite number")
+    return number
+
+
+def check_dim_value(name: str, value: Any) -> Any:
+    """``value`` coerced to what ``name`` stores, or ``TypeError``/``ValueError`` naming it.
+
+    Nothing here writes; the backends call this before touching a table.
+    """
+    key = str(name).strip().upper()
+    spec = DIM_VARIABLE_RANGES.get(key)
+    if spec is None:
+        raise ValueError(
+            f"{name}: not a dimension variable this tool writes; allowed: "
+            f"{sorted(DIM_VARIABLE_WHITELIST)}"
+        )
+    if isinstance(spec, (set, frozenset)):
+        number = _number(key, value)
+        if number != int(number) or int(number) not in spec:
+            raise ValueError(f"{key}: {value!r} is not one of {sorted(spec)}")
+        return int(number)
+    kind = spec[0]
+    if kind in ("float", "nonzero_float"):
+        number = _number(key, value)
+        low, high = spec[1], spec[2]
+        if not low <= number <= high:
+            low_text = "greater than 0" if 0 < low < 1e-6 else f"at least {low:g}"
+            raise ValueError(
+                f"{key}: {number:g} is out of range - must be {low_text} and at most {high:g}."
+            )
+        if kind == "nonzero_float" and number == 0.0:
+            raise ValueError(f"{key}: 0 is refused (AutoCAD treats it as no factor at all)")
+        return number
+    if kind == "int":
+        number = _number(key, value)
+        if number != int(number):
+            raise ValueError(f"{key}: {value!r} must be a whole number")
+        low, high = spec[1], spec[2]
+        if not low <= number <= high:
+            raise ValueError(f"{key}: {int(number)} is out of range {low}..{high}")
+        return int(number)
+    if not isinstance(value, str):
+        raise TypeError(f"{key}: expected a string, got {type(value).__name__}")
+    if kind == "char":
+        if len(value) != 1:
+            raise ValueError(f"{key}: {value!r} must be exactly one character")
+        return value
+    if kind == "name":
+        text = value.strip()
+        if not text:
+            raise ValueError(f"{key}: a style name cannot be empty")
+        bad = sorted(set(text) & _ILLEGAL_NAME_CHARS)
+        if bad:
+            raise ValueError(f"{key}: {text!r} contains characters DXF forbids in a name: {bad}")
+        return text
+    return value  # "str"
+
+
+def validate_overrides(overrides: dict | None) -> dict[str, Any]:
+    """``overrides`` as a typed, upper-cased dict — every key checked, nothing written."""
+    if overrides is None:
+        return {}
+    if not isinstance(overrides, dict):
+        raise TypeError(f"overrides: expected a mapping, got {type(overrides).__name__}")
+    typed: dict[str, Any] = {}
+    for raw_key, value in overrides.items():
+        key = str(raw_key).strip().upper()
+        typed[key] = check_dim_value(key, value)
+    return typed
+
+
+def resolve_dimstyle(preset: str | None, overrides: dict | None) -> dict[str, Any]:
+    """The preset's seventeen values with ``overrides`` applied on top.
+
+    ``preset`` ``None`` means the ISO-25 base. An unknown preset, an override
+    key outside :data:`DIM_VARIABLE_WHITELIST` or a value outside its range
+    raises ``ValueError`` (``TypeError`` for the wrong type) naming the key —
+    before anything is written, because nothing here writes.
+    """
+    key = "iso-25" if preset is None else str(preset).strip().lower()
+    if key not in PRESETS:
+        raise ValueError(f"preset: unknown value {preset!r}; use one of {sorted(PRESETS)}")
+    values = dict(PRESETS[key])
+    values.update(validate_overrides(overrides))
+    return values
+
+
+def describe_preset(name: str) -> dict:
+    """``{name, source, values, textstyle}`` for a preset, or ``ValueError``."""
+    key = str(name).strip().lower()
+    if key not in PRESETS:
+        raise ValueError(f"preset: unknown value {name!r}; use one of {sorted(PRESETS)}")
+    return {
+        "name": key,
+        "source": PRESET_SOURCES[key],
+        "values": dict(PRESETS[key]),
+        "textstyle": PRESETS[key]["DIMTXSTY"],
+    }

engineering/standards/mleaderstyles.py

@@ -0,0 +1,66 @@
+"""Multileader style presets: arrow, landing gap, text style and height.
+
+Sized to match the dimension presets they sit beside (ISO-25: 2.5 mm arrows
+and lettering; ANSI: 3 mm), so a leader note and a dimension on the same
+sheet read at one size. Only ezdxf can author an MLEADERSTYLE object;
+ActiveX exposes no collection for it (see ``backends/contracts/styles.py``).
+"""
+
+from __future__ import annotations
+
+import math
+from typing import Any
+
+__all__ = ["MLEADER_KEYS", "MLEADER_PRESETS", "resolve_mleaderstyle"]
+
+MLEADER_PRESETS: dict[str, dict[str, Any]] = {
+    "iso": {"arrow_size": 2.5, "landing_gap": 1.0, "text_style": "ISOCP", "text_height": 2.5},
+    "ansi": {"arrow_size": 3.0, "landing_gap": 1.5, "text_style": "ROMANS", "text_height": 3.0},
+}
+
+MLEADER_KEYS: tuple[str, ...] = ("arrow_size", "landing_gap", "text_style", "text_height")
+
+_ILLEGAL_NAME_CHARS = frozenset('<>/\\":;?*|,=`')
+
+
+def _positive(key: str, value: Any, *, allow_zero: bool = False) -> float:
+    if isinstance(value, bool) or not isinstance(value, (int, float)):
+        raise TypeError(f"{key}: expected a number, got {type(value).__name__}")
+    number = float(value)
+    if not math.isfinite(number):
+        raise ValueError(f"{key}: {value!r} is not a finite number")
+    if number < 0.0 or (number == 0.0 and not allow_zero):
+        raise ValueError(f"{key}: {value!r} must be greater than 0")
+    return number
+
+
+def resolve_mleaderstyle(preset: str, overrides: dict | None = None) -> dict[str, Any]:
+    """The preset's four values with ``overrides`` applied; refusals name the key."""
+    key = str(preset).strip().lower() if preset is not None else ""
+    if key not in MLEADER_PRESETS:
+        raise ValueError(f"preset: unknown value {preset!r}; use one of {sorted(MLEADER_PRESETS)}")
+    values = dict(MLEADER_PRESETS[key])
+    if overrides is None:
+        return values
+    if not isinstance(overrides, dict):
+        raise TypeError(f"overrides: expected a mapping, got {type(overrides).__name__}")
+    for raw_key, value in overrides.items():
+        name = str(raw_key).strip().lower()
+        if name not in MLEADER_KEYS:
+            raise ValueError(
+                f"overrides: {raw_key!r} is not a leader style key; allowed: {list(MLEADER_KEYS)}"
+            )
+        if name == "text_style":
+            if not isinstance(value, str) or not value.strip():
+                raise ValueError("text_style: a text style name cannot be empty")
+            bad = sorted(set(value.strip()) & _ILLEGAL_NAME_CHARS)
+            if bad:
+                raise ValueError(
+                    f"text_style: {value!r} contains characters DXF forbids in a name: {bad}"
+                )
+            values[name] = value.strip()
+        elif name == "landing_gap":
+            values[name] = _positive(name, value, allow_zero=True)
+        else:
+            values[name] = _positive(name, value)
+    return values

engineering/standards/textstyles.py

@@ -0,0 +1,100 @@
+"""Text style presets: the four fonts the standards data refers to by name.
+
+``TEXT_PRESETS`` maps a style name to ``(font file, width factor, oblique
+degrees)``. ISOCP is AutoCAD's ISO 3098 type B lettering as an SHX shape
+file; ISOCPEUR is the TrueType twin with accented characters; ARIAL is the
+general-purpose TrueType face; ROMANS is AutoCAD's simplex roman, the face
+ASME Y14.2 Gothic lettering is usually drawn with. A DXF stores only the font
+*name*, so an unknown file is never refused here: ``resolve_font`` says
+whether it is a bundled preset, the backend adds whether its font path has
+it, and the caller sees ``font_resolved``.
+"""
+
+from __future__ import annotations
+
+from pathlib import PurePath
+
+__all__ = [
+    "MAX_OBLIQUE_DEG",
+    "TEXT_PRESETS",
+    "resolve_font",
+    "validate_textstyle",
+]
+
+TEXT_PRESETS: dict[str, tuple[str, float, float]] = {
+    "ISOCP": ("isocp.shx", 1.0, 0.0),
+    "ISOCPEUR": ("isocpeur.ttf", 1.0, 0.0),
+    "ARIAL": ("arial.ttf", 1.0, 0.0),
+    "ROMANS": ("romans.shx", 1.0, 0.0),
+}
+
+#: AutoCAD's own limit for the STYLE command's obliquing angle.
+MAX_OBLIQUE_DEG = 85.0
+
+_ILLEGAL_NAME_CHARS = frozenset('<>/\\":;?*|,=`')
+
+
+def resolve_font(font: str) -> tuple[str, bool]:
+    """``(font_file, known)``: a preset name or file resolves to the bundled
+    file with ``known=True``; anything else is passed through with ``False``.
+
+    Accepts the style name (``ISOCP``), the file (``isocp.shx``) or the stem
+    (``isocp``), case-insensitively. Refuses an empty string or control
+    characters — the only inputs a DXF cannot hold.
+    """
+    if not isinstance(font, str):
+        raise TypeError(f"font: expected a string, got {type(font).__name__}")
+    text = font.strip()
+    if not text:
+        raise ValueError("font: a font file name cannot be empty")
+    if any(ord(ch) < 32 for ch in text):
+        raise ValueError("font: control characters are refused")
+    upper = text.upper()
+    if upper in TEXT_PRESETS:
+        return TEXT_PRESETS[upper][0], True
+    for font_file, _width, _oblique in TEXT_PRESETS.values():
+        if upper in (font_file.upper(), PurePath(font_file).stem.upper()):
+            return font_file, True
+    return text, False
+
+
+def validate_textstyle(
+    name: str,
+    font: str,
+    height: float = 0.0,
+    width_factor: float = 1.0,
+    oblique_deg: float = 0.0,
+) -> dict:
+    """The typed request both engines write, or a ``ValueError``/``TypeError``
+    naming the field. ``height`` 0 is AutoCAD's "prompt per text" and is legal;
+    the width factor must be positive; the oblique angle is AutoCAD's ±85°."""
+    if not isinstance(name, str) or not name.strip():
+        raise ValueError("name: a text style name cannot be empty")
+    clean = name.strip()
+    bad = sorted(set(clean) & _ILLEGAL_NAME_CHARS)
+    if bad:
+        raise ValueError(f"name: {clean!r} contains characters DXF forbids in a name: {bad}")
+    font_file, known = resolve_font(font)
+    for key, value in (
+        ("height", height),
+        ("width_factor", width_factor),
+        ("oblique_deg", oblique_deg),
+    ):
+        if isinstance(value, bool) or not isinstance(value, (int, float)):
+            raise TypeError(f"{key}: expected a number, got {type(value).__name__}")
+    if float(height) < 0.0:
+        raise ValueError(f"height: {height!r} is negative; 0 means 'ask per text'")
+    if float(width_factor) <= 0.0:
+        raise ValueError(f"width_factor: {width_factor!r} must be greater than 0")
+    if abs(float(oblique_deg)) > MAX_OBLIQUE_DEG:
+        raise ValueError(
+            f"oblique_deg: {oblique_deg!r} is outside AutoCAD's +/-{MAX_OBLIQUE_DEG:g} degrees"
+        )
+    return {
+        "name": clean,
+        "font_file": font_file,
+        "known": known,
+        "height": float(height),
+        "width_factor": float(width_factor),
+        "oblique_deg": float(oblique_deg),
+    }

tests/test_standards_presets.py

@@ -0,0 +1,326 @@
+# tests/test_standards_presets.py
+"""Provenance for the authored style presets, pinned by name.
+
+Every ISO-25 and ANSI value is asserted against the table in spec §4.1 — a
+reader with ISO 129-1 / ISO 3098-1 / ASME Y14.2 open can check each line.
+The refusals are pinned too: a value the standards data lets through is a
+value a backend writes, so the data is where "nothing written on refusal"
+starts.
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from engineering.standards.dimstyles import (
+    DIM_VARIABLE_RANGES,
+    DIM_VARIABLE_WHITELIST,
+    LINEWEIGHT_CODES,
+    PRESET_VARIABLES,
+    PRESETS,
+    check_dim_value,
+    describe_preset,
+    resolve_dimstyle,
+    validate_overrides,
+)
+from engineering.standards.mleaderstyles import (
+    MLEADER_KEYS,
+    MLEADER_PRESETS,
+    resolve_mleaderstyle,
+)
+from engineering.standards.textstyles import TEXT_PRESETS, resolve_font, validate_textstyle
+
+# ── ISO-25: ISO 129-1:2018 at the 2.5 mm row of ISO 3098-1 ──────────────────
+
+ISO_25_EXPECTED = {
+    "DIMTXT": 2.5,
+    "DIMASZ": 2.5,
+    "DIMEXE": 1.25,
+    "DIMEXO": 0.625,
+    "DIMGAP": 0.625,
+    "DIMTAD": 1,
+    "DIMTIH": 0,
+    "DIMTOH": 0,
+    "DIMDEC": 2,
+    "DIMDSEP": ",",
+    "DIMLUNIT": 2,
+    "DIMZIN": 8,
+    "DIMBLK": "",
+    "DIMTXSTY": "ISOCP",
+    "DIMLWD": -2,
+    "DIMLWE": -2,
+    "DIMSCALE": 1.0,
+}
+
+# ── ANSI: ASME Y14.2-2014, metric values ────────────────────────────────────
+
+ANSI_EXPECTED = {
+    "DIMTXT": 3.0,
+    "DIMASZ": 3.0,
+    "DIMEXE": 1.5,
+    "DIMEXO": 1.5,
+    "DIMGAP": 1.0,
+    "DIMTAD": 0,
+    "DIMTIH": 1,
+    "DIMTOH": 1,
+    "DIMDEC": 2,
+    "DIMDSEP": ".",
+    "DIMLUNIT": 2,
+    "DIMZIN": 8,
+    "DIMBLK": "",
+    "DIMTXSTY": "ROMANS",
+    "DIMLWD": -2,
+    "DIMLWE": -2,
+    "DIMSCALE": 1.0,
+}
+
+
+@pytest.mark.parametrize(("variable", "expected"), sorted(ISO_25_EXPECTED.items()))
+def test_iso25_value_by_name(variable, expected):
+    assert PRESETS["iso-25"][variable] == expected
+    assert type(PRESETS["iso-25"][variable]) is type(expected)
+
+
+@pytest.mark.parametrize(("variable", "expected"), sorted(ANSI_EXPECTED.items()))
+def test_ansi_value_by_name(variable, expected):
+    assert PRESETS["ansi"][variable] == expected
+    assert type(PRESETS["ansi"][variable]) is type(expected)
+
+
+def test_presets_set_exactly_the_seventeen_spec_variables():
+    assert len(PRESET_VARIABLES) == 17
+    for name, preset in PRESETS.items():
+        assert tuple(preset) == PRESET_VARIABLES, name
+
+
+def test_the_whitelist_is_the_seventeen_plus_the_sixteen_spec_extras():
+    extras = set(
+        "DIMTOL DIMTP DIMTM DIMTOLJ DIMTFAC DIMLFAC DIMRND DIMATFIT "
+        "DIMTMOVE DIMCLRD DIMCLRE DIMCLRT DIMSAH DIMBLK1 DIMBLK2 DIMCEN".split()
+    )
+    assert DIM_VARIABLE_WHITELIST == set(PRESET_VARIABLES) | extras
+    assert set(DIM_VARIABLE_RANGES) == DIM_VARIABLE_WHITELIST
+
+
+def test_iso_lineweights_are_all_legal_codes():
+    for mm in (0.13, 0.18, 0.25, 0.35, 0.5, 0.7, 1.0, 1.4, 2.0):
+        assert round(mm * 100) in LINEWEIGHT_CODES
+
+
+def test_describe_preset_names_the_standard():
+    iso = describe_preset("ISO-25")
+    assert iso["name"] == "iso-25"
+    assert "ISO 129-1" in iso["source"] and "ISO 3098-1" in iso["source"]
+    assert iso["values"] == ISO_25_EXPECTED and iso["textstyle"] == "ISOCP"
+    ansi = describe_preset("ansi")
+    assert "ASME Y14.2" in ansi["source"] and ansi["textstyle"] == "ROMANS"
+    with pytest.raises(ValueError, match="preset"):
+        describe_preset("din")
+
+
+# ── resolve_dimstyle ────────────────────────────────────────────────────────
+
+
+def test_none_preset_is_the_iso25_base():
+    assert resolve_dimstyle(None, None) == ISO_25_EXPECTED
+    assert resolve_dimstyle("ISO-25", {}) == ISO_25_EXPECTED
+    assert resolve_dimstyle("ansi", None) == ANSI_EXPECTED
+
+
+def test_overrides_apply_on_top_and_are_upper_cased_and_typed():
+    values = resolve_dimstyle("iso-25", {"dimtxt": 3, "DIMDEC": 3.0, "dimdsep": "."})
+    assert values["DIMTXT"] == 3.0 and type(values["DIMTXT"]) is float
+    assert values["DIMDEC"] == 3 and type(values["DIMDEC"]) is int
+    assert values["DIMDSEP"] == "."
+    assert values["DIMASZ"] == 2.5, "untouched values stay the preset's"
+
+
+def test_resolve_leaves_the_preset_table_untouched():
+    resolve_dimstyle("iso-25", {"DIMTXT": 9.0})
+    assert PRESETS["iso-25"]["DIMTXT"] == 2.5
+
+
+@pytest.mark.parametrize(
+    ("overrides", "fragment"),
+    [
+        ({"DIMFOO": 1}, "DIMFOO"),
+        ({"DIMDEC": 9}, "DIMDEC"),
+        ({"DIMDEC": -1}, "DIMDEC"),
+        ({"DIMDEC": 2.5}, "whole number"),
+        ({"DIMTXT": 0}, "DIMTXT"),
+        ({"DIMASZ": -1}, "DIMASZ"),
+        ({"DIMTAD": 5}, "DIMTAD"),
+        ({"DIMTIH": 2}, "DIMTIH"),
+        ({"DIMDSEP": ",,"}, "DIMDSEP"),
+        ({"DIMDSEP": ""}, "DIMDSEP"),
+        ({"DIMLWD": 27}, "DIMLWD"),
+        ({"DIMLUNIT": 0}, "DIMLUNIT"),
+        ({"DIMZIN": 16}, "DIMZIN"),
+        ({"DIMTXSTY": ""}, "DIMTXSTY"),
+        ({"DIMTXSTY": "a/b"}, "DIMTXSTY"),
+        ({"DIMLFAC": 0}, "DIMLFAC"),
+        ({"DIMTFAC": 0}, "DIMTFAC"),
+        ({"DIMCLRT": 257}, "DIMCLRT"),
+        ({"DIMRND": -0.5}, "DIMRND"),
+        ({"DIMSCALE": float("nan")}, "DIMSCALE"),
+    ],
+)
+def test_out_of_range_or_unknown_overrides_are_refused_by_name(overrides, fragment):
+    with pytest.raises(ValueError, match=fragment):
+        resolve_dimstyle("iso-25", overrides)
+
+
+@pytest.mark.parametrize(
+    ("overrides", "fragment"),
+    [
+        ({"DIMTXT": "2.5"}, "DIMTXT"),
+        ({"DIMTAD": True}, "DIMTAD"),
+        ({"DIMDSEP": 44}, "DIMDSEP"),
+        ({"DIMBLK": 0}, "DIMBLK"),
+    ],
+)
+def test_wrong_types_are_a_type_error_naming_the_key(overrides, fragment):
+    with pytest.raises(TypeError, match=fragment):
+        resolve_dimstyle("iso-25", overrides)
+
+
+def test_unknown_preset_is_refused():
+    with pytest.raises(ValueError, match="preset"):
+        resolve_dimstyle("din", None)
+    with pytest.raises(TypeError, match="overrides"):
+        resolve_dimstyle("iso-25", [("DIMTXT", 2.5)])
+
+
+def test_validate_overrides_alone_is_what_modify_uses():
+    assert validate_overrides(None) == {}
+    assert validate_overrides({"dimgap": -1}) == {"DIMGAP": -1.0}, "negative gap boxes the text"
+    assert check_dim_value("dimlwe", 25) == 25
+    assert check_dim_value("DIMBLK", "_OBLIQUE") == "_OBLIQUE"
+
+
+# ── text styles ─────────────────────────────────────────────────────────────
+
+
+def test_text_presets_are_the_four_spec_fonts():
+    assert TEXT_PRESETS == {
+        "ISOCP": ("isocp.shx", 1.0, 0.0),
+        "ISOCPEUR": ("isocpeur.ttf", 1.0, 0.0),
+        "ARIAL": ("arial.ttf", 1.0, 0.0),
+        "ROMANS": ("romans.shx", 1.0, 0.0),
+    }
+
+
+@pytest.mark.parametrize(
+    ("font", "expected"),
+    [
+        ("ISOCP", "isocp.shx"),
+        ("isocp", "isocp.shx"),
+        ("isocp.shx", "isocp.shx"),
+        ("ISOCP.SHX", "isocp.shx"),
+        ("ISOCPEUR", "isocpeur.ttf"),
+        ("arial", "arial.ttf"),
+        ("Arial.ttf", "arial.ttf"),
+        ("romans.shx", "romans.shx"),
+    ],
+)
+def test_a_preset_font_resolves_known(font, expected):
+    assert resolve_font(font) == (expected, True)
+
+
+def test_an_unknown_font_passes_through_unknown_never_refused():
+    assert resolve_font("simplex.shx") == ("simplex.shx", False)
+    assert resolve_font("  c:/fonts/custom.ttf ") == ("c:/fonts/custom.ttf", False)
+
+
+def test_empty_or_control_font_names_are_refused():
+    with pytest.raises(ValueError, match="font"):
+        resolve_font("")
+    with pytest.raises(ValueError, match="font"):
+        resolve_font("bad\nfont.shx")
+    with pytest.raises(TypeError, match="font"):
+        resolve_font(None)
+
+
+def test_validate_textstyle_types_the_request():
+    spec = validate_textstyle(" ISOCP ", "isocp", 0, 1, 0)
+    assert spec == {
+        "name": "ISOCP",
+        "font_file": "isocp.shx",
+        "known": True,
+        "height": 0.0,
+        "width_factor": 1.0,
+        "oblique_deg": 0.0,
+    }
+
+
+@pytest.mark.parametrize(
+    ("kwargs", "fragment"),
+    [
+        ({"name": ""}, "name"),
+        ({"name": "A:B"}, "name"),
+        ({"height": -1}, "height"),
+        ({"width_factor": 0}, "width_factor"),
+        ({"oblique_deg": 86}, "oblique_deg"),
+        ({"oblique_deg": -90}, "oblique_deg"),
+    ],
+)
+def test_validate_textstyle_refuses_by_field(kwargs, fragment):
+    base = {
+        "name": "T",
+        "font": "arial.ttf",
+        "height": 0.0,
+        "width_factor": 1.0,
+        "oblique_deg": 0.0,
+    }
+    base.update(kwargs)
+    with pytest.raises(ValueError, match=fragment):
+        validate_textstyle(**base)
+
+
+def test_validate_textstyle_refuses_wrong_types():
+    with pytest.raises(TypeError, match="width_factor"):
+        validate_textstyle("T", "arial.ttf", 0.0, "1", 0.0)
+    with pytest.raises(TypeError, match="height"):
+        validate_textstyle("T", "arial.ttf", True, 1.0, 0.0)
+
+
+# ── multileader styles ──────────────────────────────────────────────────────
+
+
+def test_mleader_presets_match_the_plan():
+    assert MLEADER_PRESETS == {
+        "iso": {"arrow_size": 2.5, "landing_gap": 1.0, "text_style": "ISOCP", "text_height": 2.5},
+        "ansi": {"arrow_size": 3.0, "landing_gap": 1.5, "text_style": "ROMANS", "text_height": 3.0},
+    }
+    assert MLEADER_KEYS == ("arrow_size", "landing_gap", "text_style", "text_height")
+
+
+def test_resolve_mleaderstyle_applies_overrides():
+    values = resolve_mleaderstyle("ISO", {"arrow_size": 3, "text_style": " ARIAL "})
+    assert values == {
+        "arrow_size": 3.0,
+        "landing_gap": 1.0,
+        "text_style": "ARIAL",
+        "text_height": 2.5,
+    }
+    assert resolve_mleaderstyle("ansi") == MLEADER_PRESETS["ansi"]
+    assert resolve_mleaderstyle("iso", {"landing_gap": 0})["landing_gap"] == 0.0
+
+
+@pytest.mark.parametrize(
+    ("preset", "overrides", "exc", "fragment"),
+    [
+        ("din", None, ValueError, "preset"),
+        (None, None, ValueError, "preset"),
+        ("iso", {"colour": 1}, ValueError, "colour"),
+        ("iso", {"arrow_size": 0}, ValueError, "arrow_size"),
+        ("iso", {"text_height": -2}, ValueError, "text_height"),
+        ("iso", {"text_style": ""}, ValueError, "text_style"),
+        ("iso", {"text_style": "a|b"}, ValueError, "text_style"),
+        ("iso", {"arrow_size": "2.5"}, TypeError, "arrow_size"),
+        ("iso", ["arrow_size"], TypeError, "overrides"),
+    ],
+)
+def test_resolve_mleaderstyle_refuses_by_name(preset, overrides, exc, fragment):
+    with pytest.raises(exc, match=fragment):
+        resolve_mleaderstyle(preset, overrides)