diff --git a/tests/unit/test_architecture.py b/tests/unit/test_architecture.py
new file mode 100644
index 0000000..9281e67
--- /dev/null
+++ b/tests/unit/test_architecture.py
@@ -0,0 +1,197 @@
+"""Architecture and layering rules - see ``docs/architecture.md``.
+
+The documented dependency stack is ``views -> viewmodels -> services -> core``;
+each layer may only import from itself or a lower layer, ``core`` stays free of
+Qt/solver/plotting libraries, and the rendering backend is confined to
+``views/canvas3d``. These tests never import the application modules; they read
+the source tree with ``ast`` so the import discipline can be checked without
+executing Qt or the solver. Directories that do not exist yet simply have
+nothing to walk, which trivially satisfies a "forbidden import" rule.
+"""
+
+from __future__ import annotations
+
+import ast
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[2]
+SRC = ROOT / "src" / "otko"
+CANVAS = SRC / "views" / "canvas3d"
+
+# Qt binding roots, in every spelling the project might use.
+QT_ROOTS = {"PySide6", "PyQt5", "PyQt6", "PySide"}
+
+# core/ stays pure - no Qt and no solver/mesh/render libraries.
+CORE_FORBIDDEN = QT_ROOTS | {
+    "openseespy",
+    "opstool",
+    "shapely",
+    "vtk",
+    "pyvista",
+    "plotly",
+    "matplotlib",
+}
+
+# Only views/canvas3d/ may touch a 3D or plotting backend.
+VTK_ROOTS = {"pyvista", "pyvistaqt", "vtk", "plotly"}
+
+
+def _iter_python_files(root: Path) -> list[Path]:
+    """Return every ``*.py`` file below ``root``, or ``[]`` if it is absent."""
+    if not root.exists():
+        return []
+    return sorted(root.rglob("*.py"))
+
+
+def _root_imports(path: Path) -> set[str]:
+    """Return the top-level module names imported by a Python source file.
+
+    Handles ``import X``, ``import X.Y``, ``from X import ...`` and
+    ``from X.Y import ...``. Relative imports are ignored: they cannot reach
+    a third-party package.
+    """
+    tree = ast.parse(path.read_text(encoding="utf-8"), filename=str(path))
+    roots: set[str] = set()
+    for node in ast.walk(tree):
+        if isinstance(node, ast.Import):
+            for alias in node.names:
+                roots.add(alias.name.split(".", 1)[0])
+        elif isinstance(node, ast.ImportFrom) and node.level == 0 and node.module:
+            roots.add(node.module.split(".", 1)[0])
+    return roots
+
+
+def _is_within(path: Path, directory: Path) -> bool:
+    """Return True when ``path`` lies inside ``directory`` (lexical check)."""
+    try:
+        path.relative_to(directory)
+    except ValueError:
+        return False
+    return True
+
+
+def _violations(
+    root: Path,
+    forbidden: set[str],
+    *,
+    skip: tuple[Path, ...] = (),
+    exclude_dir: Path | None = None,
+) -> list[str]:
+    """Return ``"<path>: <module>"`` entries for every forbidden import found."""
+    found: list[str] = []
+    for path in _iter_python_files(root):
+        if path in skip:
+            continue
+        if exclude_dir is not None and _is_within(path, exclude_dir):
+            continue
+        for module in sorted(_root_imports(path) & forbidden):
+            found.append(f"{path.relative_to(ROOT)}: {module}")
+    return found
+
+
+def test_architecture_core_has_no_qt_or_solver() -> None:
+    """core/ imports no Qt, solver, mesh, or plotting library."""
+    violations = _violations(SRC / "core", CORE_FORBIDDEN)
+    assert violations == [], f"forbidden imports in core/: {violations}"
+
+
+def test_architecture_services_no_qt_except_worker() -> None:
+    """No Qt in services/ except services/qt_workers.py."""
+    violations = _violations(
+        SRC / "services",
+        QT_ROOTS,
+        skip=(SRC / "services" / "qt_workers.py",),
+    )
+    assert violations == [], f"forbidden Qt imports in services/: {violations}"
+
+
+def test_architecture_views_no_solver() -> None:
+    """views/ imports neither openseespy nor opstool."""
+    violations = _violations(SRC / "views", {"openseespy", "opstool"})
+    assert violations == [], f"solver imports in views/: {violations}"
+
+
+def test_no_vtk_import_outside_canvas() -> None:
+    """3D/plot backends stay under views/canvas3d/."""
+    violations = _violations(SRC, VTK_ROOTS, exclude_dir=CANVAS)
+    assert violations == [], f"backend imports outside views/canvas3d/: {violations}"
+
+
+# The documented dependency stack; ``commands`` sits beside viewmodels (a VM
+# creates commands) and ``views`` is the top, so it is excluded from this map.
+_LAYER_ORDER = {"core": 0, "services": 1, "viewmodels": 2, "views": 3}
+
+
+def _internal_imports(path: Path) -> set[str]:
+    """Return the fully-qualified ``otko.*`` modules imported by a source file."""
+    tree = ast.parse(path.read_text(encoding="utf-8"), filename=str(path))
+    found: set[str] = set()
+    for node in ast.walk(tree):
+        if isinstance(node, ast.Import):
+            found.update(alias.name for alias in node.names)
+        elif isinstance(node, ast.ImportFrom) and node.level == 0 and node.module:
+            found.add(node.module)
+    return {module for module in found if module.startswith("otko.")}
+
+
+def test_architecture_lower_layers_do_not_import_higher() -> None:
+    """core/services/viewmodels never import a higher layer."""
+    violations: list[str] = []
+    for path in _iter_python_files(SRC):
+        layer = path.relative_to(SRC).parts[0]
+        if layer not in _LAYER_ORDER:
+            continue
+        for module in _internal_imports(path):
+            target = module.split(".")[1] if "." in module else ""
+            if target in _LAYER_ORDER and _LAYER_ORDER[target] > _LAYER_ORDER[layer]:
+                violations.append(f"{path.relative_to(ROOT)}: {layer} -> {module}")
+    assert violations == [], f"lower layer imports a higher layer: {violations}"
+
+
+def test_architecture_viewmodels_do_not_construct_widgets() -> None:
+    """viewmodels emit signals and import no Qt widgets."""
+    violations = _violations(SRC / "viewmodels", {"QtWidgets"})
+    assert violations == [], f"viewmodels import widgets: {violations}"
+    for path in _iter_python_files(SRC / "viewmodels"):
+        assert "PySide6.QtWidgets" not in path.read_text(encoding="utf-8"), path
+
+
+def test_architecture_report_is_qt_and_solver_free() -> None:
+    """report generation imports no Qt or solver (vacuous if absent)."""
+    report = SRC / "services" / "report"
+    violations = _violations(report, QT_ROOTS | {"openseespy", "opstool"})
+    assert violations == [], f"report imports Qt/solver: {violations}"
+
+
+def test_architecture_project_vm_owns_the_undo_stack() -> None:
+    """Only project_vm.py holds a QUndoStack."""
+    holders = [
+        path.name
+        for path in _iter_python_files(SRC / "viewmodels")
+        if "QUndoStack" in path.read_text(encoding="utf-8")
+    ]
+    assert holders == ["project_vm.py"], f"QUndoStack holders: {holders}"
+
+
+def test_architecture_no_environment_configuration() -> None:
+    """No env-var configuration anywhere in src/otko."""
+    offenders = [
+        str(path.relative_to(ROOT))
+        for path in _iter_python_files(SRC)
+        if "os.environ" in path.read_text(encoding="utf-8")
+        or "os.getenv" in path.read_text(encoding="utf-8")
+    ]
+    assert offenders == [], f"environment configuration in: {offenders}"
+
+
+def test_architecture_runner_splits_emit_and_run() -> None:
+    """Model emission and analysis live in separate modules."""
+    emit_path = SRC / "services" / "_emit.py"
+    run_path = SRC / "services" / "_run.py"
+    assert emit_path.exists()
+    assert run_path.exists()
+    emit_source = emit_path.read_text(encoding="utf-8")
+    run_source = run_path.read_text(encoding="utf-8")
+    assert "class OpenSeesEmitter" in emit_source
+    assert "class OpenSeesAnalysisRunner" in run_source
+    assert "OpenSeesEmitter" in run_source
diff --git a/tests/unit/test_ci_config.py b/tests/unit/test_ci_config.py
new file mode 100644
index 0000000..063f9b3
--- /dev/null
+++ b/tests/unit/test_ci_config.py
@@ -0,0 +1,39 @@
+"""Meta-gate checks for the CI workflow and pre-commit hook configuration."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[2]
+CI = ROOT / ".github" / "workflows" / "ci.yml"
+PRECOMMIT = ROOT / ".pre-commit-config.yaml"
+
+HEADLESS_COMMAND = 'pytest tests/unit tests/services -m "not slow"'
+
+
+def test_ci_declares_all_jobs() -> None:
+    """The workflow exposes the lint/type/test split as separate jobs."""
+    text = CI.read_text(encoding="utf-8")
+    for job in ("lint:", "type:", "test-headless:", "test-gui:", "test-integration:"):
+        assert f"\n  {job}\n" in text, f"missing CI job: {job}"
+
+
+def test_ci_runs_the_headless_command() -> None:
+    """The headless job runs the unit + services, non-slow command verbatim."""
+    assert HEADLESS_COMMAND in CI.read_text(encoding="utf-8")
+
+
+def test_precommit_declares_expected_hooks() -> None:
+    """The pre-commit config wires up the lint/format/type/hygiene hooks."""
+    text = PRECOMMIT.read_text(encoding="utf-8")
+    for hook in (
+        "id: ruff",
+        "id: ruff-format",
+        "id: mypy",
+        "id: trailing-whitespace",
+        "id: end-of-file-fixer",
+        "id: check-yaml",
+        "id: check-added-large-files",
+        "id: check-merge-conflict",
+    ):
+        assert hook in text, f"missing pre-commit hook: {hook}"
diff --git a/tests/unit/test_docs.py b/tests/unit/test_docs.py
new file mode 100644
index 0000000..f8c78e0
--- /dev/null
+++ b/tests/unit/test_docs.py
@@ -0,0 +1,51 @@
+"""Documentation gates — assert the user-facing docs keep their key content.
+
+Pure pathlib; no Qt or solver imports so this stays part of the fast unit
+suite.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[2]
+DOCS_DIR = REPO_ROOT / "docs"
+
+
+def _text(path: Path) -> str:
+    """Return a file's UTF-8 text with normalized line endings."""
+    return path.read_text(encoding="utf-8").replace("\r\n", "\n")
+
+
+def test_quick_guide_exists_and_covers_core_topics() -> None:
+    quick_guide = DOCS_DIR / "QUICK_GUIDE.md"
+    assert quick_guide.is_file(), "docs/QUICK_GUIDE.md is missing"
+
+    lowered = _text(quick_guide).lower()
+    for topic in ("cantilever", "report", "modal", "units", "undo"):
+        assert topic in lowered, f"QUICK_GUIDE.md is missing {topic!r}"
+
+
+def test_contributing_describes_this_repo() -> None:
+    text = _text(REPO_ROOT / "CONTRIBUTING.md")
+
+    for required in (
+        "views",
+        "viewmodels",
+        "services",
+        "core",
+        "commands",
+        "Conventional Commits",
+        "feat:",
+        "main",
+        "pre-commit install",
+        'pip install -e ".[gui,dev]"',
+        "python -m otko",
+        'pytest -m "not slow"',
+    ):
+        assert required in text, f"CONTRIBUTING.md is missing {required!r}"
+
+
+def test_readme_links_quick_guide() -> None:
+    readme = _text(REPO_ROOT / "README.md")
+    assert "docs/QUICK_GUIDE.md" in readme
diff --git a/tests/unit/test_meta_gates.py b/tests/unit/test_meta_gates.py
new file mode 100644
index 0000000..67ee070
--- /dev/null
+++ b/tests/unit/test_meta_gates.py
@@ -0,0 +1,29 @@
+"""Meta-gates tying the test markers to the CI commands that consume them."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+try:
+    import tomllib
+except ModuleNotFoundError:  # Python < 3.11
+    import tomli as tomllib
+
+ROOT = Path(__file__).resolve().parents[2]
+PYPROJECT = ROOT / "pyproject.toml"
+CI = ROOT / ".github" / "workflows" / "ci.yml"
+
+HEADLESS_COMMAND = 'pytest tests/unit tests/services -m "not slow"'
+
+
+def test_slow_marker_is_declared() -> None:
+    """``[tool.pytest.ini_options]`` registers the ``slow`` marker."""
+    with PYPROJECT.open("rb") as handle:
+        config = tomllib.load(handle)
+    markers = config["tool"]["pytest"]["ini_options"]["markers"]
+    assert any(marker.startswith("slow:") for marker in markers), markers
+
+
+def test_ci_runs_the_headless_command() -> None:
+    """The headless CI command matches the marker the suite expects."""
+    assert HEADLESS_COMMAND in CI.read_text(encoding="utf-8")
diff --git a/tests/unit/test_packaging.py b/tests/unit/test_packaging.py
new file mode 100644
index 0000000..7b16ea4
--- /dev/null
+++ b/tests/unit/test_packaging.py
@@ -0,0 +1,72 @@
+"""Packaging invariants — version/solver single-sourcing and dependency hygiene.
+
+Pure static checks over the repository files. No imports of :mod:`otko`,
+Qt or the solver stack, so this test runs anywhere (including Windows 3.12).
+"""
+
+from __future__ import annotations
+
+import re
+from pathlib import Path
+
+try:  # Python 3.11+
+    import tomllib
+except ModuleNotFoundError:  # pragma: no cover - Python 3.10 backport
+    import tomli as tomllib
+
+REPO_ROOT = Path(__file__).resolve().parents[2]
+SRC_ROOT = REPO_ROOT / "src" / "otko"
+PYPROJECT = REPO_ROOT / "pyproject.toml"
+
+_VERSION_RE = re.compile(r"^__version__\s*=", re.MULTILINE)
+
+
+def _pyproject() -> dict:
+    with PYPROJECT.open("rb") as handle:
+        return tomllib.load(handle)
+
+
+def _src_files() -> list[Path]:
+    return sorted(SRC_ROOT.rglob("*.py"))
+
+
+def _dep_name(requirement: str) -> str:
+    """Return the lowercased distribution name from a PEP 508 requirement."""
+    match = re.match(r"^\s*([A-Za-z0-9][A-Za-z0-9._-]*)", requirement)
+    return match.group(1).lower().replace("_", "-") if match else ""
+
+
+def test_console_script_entrypoint() -> None:
+    assert _pyproject()["project"]["scripts"]["otko"] == "otko.__main__:main"
+
+
+def test_project_version_is_dynamic() -> None:
+    project = _pyproject()["project"]
+    assert "version" not in project
+    assert project["dynamic"] == ["version"]
+
+
+def test_single_version_assignment() -> None:
+    hits = [path for path in _src_files() if _VERSION_RE.search(path.read_text(encoding="utf-8"))]
+    assert len(hits) == 1, f"expected exactly one __version__ assignment, got {hits}"
+    assert hits[0] == SRC_ROOT / "_const.py"
+
+
+def test_solver_version_literal_only_in_const() -> None:
+    hits = [path for path in _src_files() if "3.8.0.0" in path.read_text(encoding="utf-8")]
+    assert hits == [SRC_ROOT / "_const.py"], f"unexpected 3.8.0.0 occurrences: {hits}"
+
+
+def test_ruff_line_length_and_ignore() -> None:
+    ruff = _pyproject()["tool"]["ruff"]
+    assert ruff["line-length"] == 100
+    assert "E501" in ruff["lint"]["ignore"]
+
+
+def test_no_phantom_scipy_pandas_dependencies() -> None:
+    project = _pyproject()["project"]
+    groups = [project.get("dependencies", [])]
+    groups.extend(project.get("optional-dependencies", {}).values())
+    declared = {_dep_name(req) for group in groups for req in group}
+    assert "scipy" not in declared
+    assert "pandas" not in declared