diff --git a/app/validate.py b/app/validate.py
index 584972a..f2de7ec 100644
--- a/app/validate.py
+++ b/app/validate.py
@@ -1,7 +1,7 @@
 """Validate seed JSON against the schema and conventions (§9.3, §15.3).
 
 Checks: required fields, slug convention (§14.1), value ranges/units (§14.3),
-and foreign-key integrity by slug. Run with ``python -m app.validate``;
+integer-typed fields, and foreign-key integrity by slug. Run with ``python -m app.validate``;
 exits non-zero on the first failure set (used by CI ``validate-data.yml``).
 
 ``DATA_DIR`` defaults to the nearest TechAPI data checkout and can be
@@ -146,6 +146,83 @@
 
 DATE_RE = re.compile(r"^\d{4}-\d{2}-\d{2}$")
 
+# Fields the models (app/models/) type as int, per category. Kept by hand so
+# this module needs nothing but the standard library: TechAPI's PR checks run
+# it without installing the engine. tests/unit/test_validate_integers.py fails
+# when a model and this list disagree.
+BRAND_INTEGERS = {"founded_year"}
+SOC_INTEGERS = {
+    "gpu_cores",
+    "gpu_clock_mhz",
+    "geekbench_single",
+    "geekbench_multi",
+    "antutu_score",
+}
+# smartphone, tablet, watch and pda share these.
+DEVICE_INTEGERS = {"msrp_usd", "battery_mah"}
+DEVICE_INTEGER_LISTS = {"storage_options_gb"}
+GPU_INTEGERS = {
+    "msrp_usd",
+    "cuda_cores",
+    "stream_processors",
+    "rt_cores",
+    "tensor_cores",
+    "memory_bus_bit",
+    "base_clock_mhz",
+    "boost_clock_mhz",
+    "tdp_w",
+    "timespy_score",
+    "passmark_g3d_mark",
+    "timespy_extreme_score",
+    "speedway_score",
+    "octanebench_score",
+}
+CPU_INTEGERS = {
+    "cores",
+    "threads",
+    "p_cores",
+    "e_cores",
+    "tdp_w",
+    "max_tdp_w",
+    "cinebench_r23_single",
+    "cinebench_r23_multi",
+    "cinebench_2024_single",
+    "cinebench_2024_multi",
+    "geekbench_single",
+    "geekbench_multi",
+    "cinebench_r15_single",
+    "cinebench_r15_multi",
+    "cinebench_r10_single",
+    "cinebench_r10_multi",
+    "passmark_single",
+    "passmark_cpu_mark",
+    "msrp_usd",
+}
+LAPTOP_INTEGERS = {"msrp_usd", "ram_gb", "storage_gb"}
+MONITOR_INTEGERS = {"msrp_usd", "refresh_hz", "ppi"}
+DEVICE_CATALOG_INTEGERS = {
+    "screen_density_dpi",
+    "android_sdk_min",
+    "android_sdk_max",
+    "release_year",
+}
+# category -> (integer fields, list-of-integer fields)
+INTEGER_FIELDS: dict[str, tuple[set[str], set[str]]] = {
+    "brand": (BRAND_INTEGERS, set()),
+    "soc": (SOC_INTEGERS, set()),
+    "smartphone": (DEVICE_INTEGERS, DEVICE_INTEGER_LISTS),
+    "tablet": (DEVICE_INTEGERS, DEVICE_INTEGER_LISTS),
+    "watch": (DEVICE_INTEGERS, DEVICE_INTEGER_LISTS),
+    "pda": (DEVICE_INTEGERS, DEVICE_INTEGER_LISTS),
+    "gpu": (GPU_INTEGERS, set()),
+    "cpu": (CPU_INTEGERS, set()),
+    "laptop": (LAPTOP_INTEGERS, set()),
+    "monitor": (MONITOR_INTEGERS, set()),
+    "software": (set(), set()),
+    "website": (set(), set()),
+    "device_catalog": (DEVICE_CATALOG_INTEGERS, set()),
+}
+
 
 def _load(subdir: str, only: set[str] | None = None) -> list[tuple[str, dict[str, Any]]]:
     """Load every ``*.json`` under ``subdir``; with ``only``, just those paths.
@@ -237,6 +314,34 @@ def _check_range(
         errors.append(f"{name}: {field}={value} out of range [{lo}, {hi}]")
 
 
+def _is_integer(value: object) -> bool:
+    # 65.0 passes: the read schemas load it as 65 and existing records hold it.
+    if isinstance(value, bool):
+        return False
+    return isinstance(value, int) or (isinstance(value, float) and value.is_integer())
+
+
+def _check_integers(
+    name: str, record: dict[str, Any], category: str, errors: list[str]
+) -> None:
+    """Fields the API types as integers must not hold 11.5, true or "12".
+
+    The table models skip validation, so such a value only fails later, when
+    the dump builds the read schema.
+    """
+    scalars, lists = INTEGER_FIELDS[category]
+    for field in sorted(scalars):
+        value = record.get(field)
+        if value is not None and not _is_integer(value):
+            errors.append(f"{name}: {field}={value!r} must be an integer")
+    for field in sorted(lists):
+        value = record.get(field)
+        if value is not None and not (
+            isinstance(value, list) and all(_is_integer(item) for item in value)
+        ):
+            errors.append(f"{name}: {field}={value!r} must be a list of integers")
+
+
 def _check_date(name: str, value: object, errors: list[str]) -> None:
     if not isinstance(value, str) or not DATE_RE.match(value):
         errors.append(f"{name}: release_date '{value}' must be ISO 8601 YYYY-MM-DD (§14.2)")
@@ -394,6 +499,7 @@ def validate(only: set[str] | None = None) -> list[str]:
             _check_unique_slugs(category, records, errors)
         for fname, rec in records:
             _check_media(fname, rec, errors)
+            _check_integers(fname, rec, category, errors)
 
     for fname, rec in brands:
         _check_required(fname, rec, BRAND_REQUIRED, errors)
@@ -580,9 +686,7 @@ def validate(only: set[str] | None = None) -> list[str]:
             ("release_year", 1990, 2100),
         ):
             value = rec.get(field)
-            if value is not None and (isinstance(value, bool) or not isinstance(value, int)):
-                errors.append(f"{fname}: {field} must be an integer")
-            else:
+            if _is_integer(value):  # anything else is reported by _check_integers
                 _check_range(fname, field, value, lo, hi, errors)
         sdk_min, sdk_max = rec.get("android_sdk_min"), rec.get("android_sdk_max")
         if isinstance(sdk_min, int) and isinstance(sdk_max, int) and sdk_max < sdk_min:
diff --git a/tests/unit/test_validate_identity.py b/tests/unit/test_validate_identity.py
index 5f7d1bc..9cebab1 100644
--- a/tests/unit/test_validate_identity.py
+++ b/tests/unit/test_validate_identity.py
@@ -79,7 +79,7 @@ def test_catalog_valid_and_required(tmp_path, monkeypatch) -> None:
 @pytest.mark.parametrize("patch,needle", [
     ({"form_factor": "phablet"}, "form_factor 'phablet'"),
     ({"device_type_guess": "tv-box"}, "device_type_guess 'tv-box'"),
-    ({"android_sdk_min": "30"}, "android_sdk_min must be an integer"),
+    ({"android_sdk_min": "30"}, "android_sdk_min='30' must be an integer"),
     ({"android_sdk_min": 0}, "android_sdk_min=0"),
     ({"promoted_to": "laptop/x"}, "promoted_to 'laptop/x'"),
     ({"promoted_to": "smartphone"}, "promoted_to 'smartphone'"),
diff --git a/tests/unit/test_validate_integers.py b/tests/unit/test_validate_integers.py
new file mode 100644
index 0000000..50fd4b2
--- /dev/null
+++ b/tests/unit/test_validate_integers.py
@@ -0,0 +1,189 @@
+"""Fields the models type as integers must hold integers in the seed JSON."""
+
+from __future__ import annotations
+
+import json
+import subprocess
+import sys
+from pathlib import Path
+from types import NoneType, UnionType
+from typing import Any, Union, get_args, get_origin
+
+import pytest
+from pydantic import BaseModel
+
+from app import validate
+from app.models.brand import Brand
+from app.models.cpu import CPU
+from app.models.device_catalog import DeviceCatalog
+from app.models.gpu import DiscreteGPU
+from app.models.laptop import Laptop
+from app.models.mobile_device import PDA, Tablet, Watch
+from app.models.monitor import Monitor
+from app.models.smartphone import Smartphone
+from app.models.soc import SoC
+from app.models.software import Software
+from app.models.website import Website
+from app.schemas import (
+    BrandRead,
+    DeviceCatalogRead,
+    LaptopRead,
+    MonitorRead,
+    SmartphoneRead,
+    SoCRead,
+    SoftwareRead,
+)
+from app.schemas.cpu import CPURead
+from app.schemas.gpu import GPURead
+from app.schemas.mobile_device import MobileDeviceRead
+from app.schemas.website import WebsiteRead
+
+REPO = Path(__file__).resolve().parents[2]
+
+MODELS: dict[str, type[BaseModel]] = dict(zip(validate.CATEGORIES, (
+    Brand, SoC, Smartphone, Tablet, Watch, PDA, DiscreteGPU, CPU,
+    Laptop, Monitor, Software, Website, DeviceCatalog,
+), strict=True))
+READ_SCHEMAS: dict[str, type[BaseModel]] = {
+    "brand": BrandRead, "soc": SoCRead, "smartphone": SmartphoneRead,
+    "tablet": MobileDeviceRead, "watch": MobileDeviceRead, "pda": MobileDeviceRead,
+    "gpu": GPURead, "cpu": CPURead, "laptop": LaptopRead, "monitor": MonitorRead,
+    "software": SoftwareRead, "website": WebsiteRead, "device_catalog": DeviceCatalogRead,
+}
+
+# One record path and one integer field per category that has any.
+SAMPLES = [
+    ("brand/us/acme.json", "founded_year"),
+    ("soc/acme/c1.json", "gpu_cores"),
+    ("smartphone/acme/2020/p.json", "battery_mah"),
+    ("tablet/acme/2020/t/t.json", "battery_mah"),
+    ("watch/acme/2020/w/w.json", "msrp_usd"),
+    ("pda/acme/2020/d/d.json", "battery_mah"),
+    ("gpu/acme/g1.json", "tdp_w"),
+    ("cpu/acme/x1.json", "tdp_w"),
+    ("laptop/acme/2020/l.json", "ram_gb"),
+    ("monitor/acme/2020/m.json", "refresh_hz"),
+    ("device_catalog/acme/acme-x.json", "android_sdk_min"),
+]
+
+
+def _put(root: Path, rel: str, rec: dict[str, Any]) -> None:
+    path = root / rel
+    path.parent.mkdir(parents=True, exist_ok=True)
+    path.write_text(json.dumps(rec), encoding="utf-8")
+
+
+def _integer_errors(tmp_path: Path, monkeypatch: pytest.MonkeyPatch, rel: str,
+                    rec: dict[str, Any], only: set[str] | None = None) -> list[str]:
+    monkeypatch.setattr(validate, "DATA_DIR", tmp_path)
+    _put(tmp_path, rel, rec)
+    return [e for e in validate.validate(only) if "must be an integer" in e
+            or "must be a list of integers" in e]
+
+
+def _integer_fields(model: type[BaseModel]) -> tuple[set[str], set[str]]:
+    """Fields a model types as ``int`` and as ``list[int]``.
+
+    Primary and foreign keys are skipped: seed fills them in, the JSON carries
+    slugs instead.
+    """
+    scalars: set[str] = set()
+    lists: set[str] = set()
+    for field, info in model.model_fields.items():
+        if getattr(info, "primary_key", None) is True or isinstance(
+            getattr(info, "foreign_key", None), str
+        ):
+            continue
+        annotation = info.annotation
+        options = get_args(annotation) if get_origin(annotation) in (Union, UnionType) else (
+            annotation,
+        )
+        kinds = {option for option in options if option is not NoneType}
+        if kinds == {int}:
+            scalars.add(field)
+        elif kinds == {list[int]}:
+            lists.add(field)
+    return scalars, lists
+
+
+def test_validator_imports_with_the_standard_library_only() -> None:
+    """TechAPI's PR checks run the validator without installing the engine."""
+    code = f"import sys; sys.path.insert(0, {str(REPO)!r}); import app.validate"
+    # -S keeps site-packages off the path, -I ignores PYTHONPATH and the cwd
+    done = subprocess.run([sys.executable, "-I", "-S", "-c", code],
+                          capture_output=True, text=True)
+    assert done.returncode == 0, done.stderr
+
+
+def test_every_category_is_mapped() -> None:
+    assert set(validate.INTEGER_FIELDS) == set(validate.CATEGORIES)
+
+
+@pytest.mark.parametrize("category", validate.CATEGORIES)
+def test_mapping_matches_the_model(category: str) -> None:
+    """Fails when a model gains or loses an integer column the validator does not list."""
+    assert validate.INTEGER_FIELDS[category] == _integer_fields(MODELS[category])
+
+
+def test_keys_floats_and_bools_are_not_integer_fields() -> None:
+    scalars, _ = _integer_fields(CPU)
+    assert not {"id", "manufacturer_id", "base_clock_ghz", "verified"} & scalars
+    assert "ram_gb" in _integer_fields(Laptop)[0]
+    assert "ram_gb" not in _integer_fields(Smartphone)[0]
+
+
+@pytest.mark.parametrize("category", validate.CATEGORIES)
+def test_read_schema_integers_are_covered(category: str) -> None:
+    """A read schema must not type a seed field as int unless the model does."""
+    schema_scalars, schema_lists = _integer_fields(READ_SCHEMAS[category])
+    scalars, lists = validate.INTEGER_FIELDS[category]
+    assert schema_scalars - {"id"} <= scalars
+    assert schema_lists <= lists
+
+
+@pytest.mark.parametrize("rel,field", SAMPLES)
+@pytest.mark.parametrize("value", [11.5, True, "12", "12.0", [12], float("nan")])
+def test_non_integer_rejected(tmp_path, monkeypatch, rel, field, value) -> None:
+    errs = _integer_errors(tmp_path, monkeypatch, rel, {"slug": "s", field: value})
+    assert errs == [f"{rel}: {field}={value!r} must be an integer"]
+
+
+@pytest.mark.parametrize("rel,field", SAMPLES)
+@pytest.mark.parametrize("value", [12, 0, 65.0, None])
+def test_integer_and_null_accepted(tmp_path, monkeypatch, rel, field, value) -> None:
+    assert _integer_errors(tmp_path, monkeypatch, rel, {"slug": "s", field: value}) == []
+
+
+def test_absent_field_accepted(tmp_path, monkeypatch) -> None:
+    assert _integer_errors(tmp_path, monkeypatch, "cpu/acme/x1.json", {"slug": "s"}) == []
+
+
+def test_float_typed_field_keeps_fractions(tmp_path, monkeypatch) -> None:
+    rec = {"slug": "s", "ram_gb": 0.5, "weight_g": 180.5}
+    assert _integer_errors(tmp_path, monkeypatch, "smartphone/acme/2020/p.json", rec) == []
+    assert _integer_errors(tmp_path, monkeypatch, "cpu/acme/x1.json",
+                           {"slug": "s", "base_clock_ghz": 3.5, "l3_cache_mb": 1.5}) == []
+
+
+@pytest.mark.parametrize("value,ok", [
+    ([], True), ([64, 128], True), ([64.0], True), (None, True),
+    ([64, 128.5], False), (["64"], False), ([True], False), (64, False), ("64", False),
+])
+def test_integer_list(tmp_path, monkeypatch, value, ok) -> None:
+    rel = "tablet/acme/2020/t/t.json"
+    errs = _integer_errors(tmp_path, monkeypatch, rel, {"slug": "s", "storage_options_gb": value})
+    expected = [] if ok else [f"{rel}: storage_options_gb={value!r} must be a list of integers"]
+    assert errs == expected
+
+
+def test_scoped_run_checks_changed_and_fk_records_only(tmp_path, monkeypatch) -> None:
+    _put(tmp_path, "laptop/acme/2020/old.json", {"slug": "old", "ram_gb": 7.5})
+    _put(tmp_path, "cpu/acme/x1.json", {"slug": "x1", "tdp_w": 5.9})
+    rel = "laptop/acme/2020/new.json"
+    errs = _integer_errors(tmp_path, monkeypatch, rel, {"slug": "new", "ram_gb": 15.5}, {rel})
+    # cpu is a foreign-key target, so a scoped run still reads all of it
+    assert errs == [
+        "cpu/acme/x1.json: tdp_w=5.9 must be an integer",
+        f"{rel}: ram_gb=15.5 must be an integer",
+    ]
+    assert len(_integer_errors(tmp_path, monkeypatch, rel, {"slug": "new"})) == 2