From 6add02edd0a7d5fa13f3200dd2177359d2088808 Mon Sep 17 00:00:00 2001
From: Joseph Magly <1159087+jmagly@users.noreply.github.com>
Date: Fri, 14 Aug 2026 12:47:33 -0400
Subject: [PATCH] test: enforce model and CLI boundary contracts

---
 .github/workflows/ci.yml             |  15 +-
 CONTRIBUTING.md                      |   7 +-
 README.md                            |   9 +-
 obliteratus/cli.py                   |   7 +
 obliteratus/device.py                |  22 +-
 obliteratus/models/loader.py         |  86 ++---
 pyproject.toml                       |   2 +-
 scripts/check_coverage_thresholds.py | 134 +++++++-
 tests/test_cli_boundaries.py         | 460 +++++++++++++++++++++++++++
 tests/test_coverage_thresholds.py    |  69 +++-
 tests/test_device_boundaries.py      | 209 ++++++++++++
 tests/test_loader_boundaries.py      | 354 +++++++++++++++++++++
 tests/test_mlx_backend_boundaries.py | 170 ++++++++++
 13 files changed, 1492 insertions(+), 52 deletions(-)
 create mode 100644 tests/test_cli_boundaries.py
 create mode 100644 tests/test_device_boundaries.py
 create mode 100644 tests/test_loader_boundaries.py
 create mode 100644 tests/test_mlx_backend_boundaries.py

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9cb18a2..1b9b8b0 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -234,6 +234,8 @@ jobs:
     steps:
       - name: Check out repository
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          fetch-depth: 0
 
       - name: Set up Python
         uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97 # v7.0.0
@@ -275,11 +277,20 @@ jobs:
             --cov-report="json:test-results/coverage-py${{ matrix.python-version }}.json"
 
       - name: Enforce line and branch coverage floors
+        env:
+          COVERAGE_BASE: ${{ github.event.pull_request.base.sha || github.event.before }}
         run: >-
           "$TEST_ENV/bin/python" scripts/check_coverage_thresholds.py
           "test-results/coverage-py${{ matrix.python-version }}.json"
-          --min-line 49
-          --min-branch 36
+          --min-line 55
+          --min-branch 42
+          --min-file obliteratus/device.py=70
+          --min-file obliteratus/models/loader.py=70
+          --min-file obliteratus/architecture_profiles.py=70
+          --min-file obliteratus/cli.py=70
+          --min-file obliteratus/mlx_backend.py=70
+          --min-changed 90
+          --base-ref "$COVERAGE_BASE"
 
       - name: Upload test and coverage evidence
         if: always()
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 3133a4b..2a873d4 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -32,6 +32,11 @@ python -m obliteratus --help
 ```
 
 All tests must pass before submitting a PR. Tests are designed to run on CPU without downloading models.
+The mandatory gate currently requires at least 55% repository statement coverage,
+42% branch coverage, 90% coverage of changed executable lines, and 70% statement
+coverage in the device, loader, architecture-profile, CLI, and simulated MLX
+boundary modules. New changes should raise these floors rather than consume the
+existing margin.
 
 ## Code Style
 
@@ -103,7 +108,7 @@ obliteratus/
   models/                # Model loading utilities
   reporting/             # Report generation
   strategies/            # Ablation strategies (layer, head, FFN, embedding)
-tests/                   # 28 test files
+tests/                   # 41 test files
 paper/                   # LaTeX paper
 examples/                # YAML config examples
 ```
diff --git a/README.md b/README.md
index 090cf49..b0a9176 100644
--- a/README.md
+++ b/README.md
@@ -651,7 +651,7 @@ obliteratus run examples/preset_quick.yaml
 | Analysis-informed abliteration | Yes (closed-loop feedback) | N/A | N/A | N/A | N/A | N/A |
 | Auto parameter optimization | Analysis-guided | N/A | Bayesian (Optuna) | N/A | N/A | N/A |
 | Model compatibility | Any HuggingFace model | ~50 architectures | 16/16 tested | TransformerLens only | HuggingFace | TransformerLens |
-| Test suite | 837 tests | Community | Unknown | None | Minimal | Moderate |
+| Test suite | 970+ tests | Community | Unknown | None | Minimal | Moderate |
 
 ## Community-powered research — every run advances the science
 
@@ -745,7 +745,7 @@ If you use OBLITERATUS in your research, please cite:
   author    = {{OBLITERATUS Contributors}},
   year      = {2026},
   url       = {https://github.com/elder-plinius/OBLITERATUS},
-  note      = {15 analysis modules, 837 tests}
+  note      = {15 analysis modules, 970+ tests}
 }
 ```
 
@@ -756,7 +756,10 @@ pip install -e ".[dev]"
 pytest
 ```
 
-837 tests across 28 test files covering CLI, all analysis modules, abliteration pipeline, architecture detection, visualization sanitization, community contributions, edge cases, and evaluation metrics.
+The mandatory CPU suite currently contains 975 tests across 41 test files,
+covering the CLI, model/device/quantization/MLX boundaries, all analysis modules,
+the abliteration pipeline, architecture detection, visualization sanitization,
+community contributions, edge cases, and evaluation metrics.
 
 ## License
 
diff --git a/obliteratus/cli.py b/obliteratus/cli.py
index 5c43d97..98548bf 100644
--- a/obliteratus/cli.py
+++ b/obliteratus/cli.py
@@ -8,6 +8,8 @@ from pathlib import Path
 
 from rich.console import Console
 
+from obliteratus import __version__
+
 console = Console()
 
 _BANNER = r"""
@@ -92,6 +94,11 @@ def main(argv: list[str] | None = None):
         prog="obliteratus",
         description="Master Ablation Suite for HuggingFace transformers",
     )
+    parser.add_argument(
+        "--version",
+        action="version",
+        version=f"%(prog)s {__version__}",
+    )
     subparsers = parser.add_subparsers(dest="command", required=True)
 
     # --- run ---
diff --git a/obliteratus/device.py b/obliteratus/device.py
index cef780b..44a6baa 100644
--- a/obliteratus/device.py
+++ b/obliteratus/device.py
@@ -58,7 +58,27 @@ def get_device(preference: str = "auto") -> str:
         if is_mps():
             return "mps"
         return "cpu"
-    return preference
+
+    if preference == "cpu":
+        return preference
+    if preference == "mps":
+        if not is_mps():
+            raise RuntimeError(
+                "MPS was requested but is unavailable. Use device='auto' for CPU fallback.",
+            )
+        return preference
+    if preference == "cuda" or (
+        preference.startswith("cuda:") and preference.removeprefix("cuda:").isdigit()
+    ):
+        if not is_cuda():
+            raise RuntimeError(
+                "CUDA was requested but is unavailable. Use device='auto' for CPU fallback.",
+            )
+        return preference
+    raise ValueError(
+        f"Unknown device {preference!r}. Choose 'auto', 'cpu', 'mps', 'cuda', "
+        "or an indexed CUDA device such as 'cuda:0'.",
+    )
 
 
 def get_device_name() -> str:
diff --git a/obliteratus/models/loader.py b/obliteratus/models/loader.py
index e59e125..4bf9815 100644
--- a/obliteratus/models/loader.py
+++ b/obliteratus/models/loader.py
@@ -323,6 +323,7 @@ class ModelHandle:
     intermediate_size: int = 0
     _original_state: Optional[dict] = field(default=None, repr=False)
     _offload_dir: Optional[str] = field(default=None, repr=False)
+    _owns_offload_dir: bool = field(default=False, repr=False)
 
     def __post_init__(self):
         cfg = self.config
@@ -369,13 +370,14 @@ class ModelHandle:
 
     def cleanup(self):
         """Remove temporary offload directory if one was auto-created."""
-        if self._offload_dir is not None:
+        if self._offload_dir is not None and self._owns_offload_dir:
             import shutil
             try:
                 shutil.rmtree(self._offload_dir, ignore_errors=True)
             except Exception:
                 pass
-            self._offload_dir = None
+        self._offload_dir = None
+        self._owns_offload_dir = False
 
     def __del__(self):
         self.cleanup()
@@ -447,6 +449,8 @@ def load_model(
     quantization: str | None = None,
     offload_folder: str | None = None,
     skip_snapshot: bool | None = None,
+    revision: str | None = None,
+    local_files_only: bool = False,
 ) -> ModelHandle:
     """Load a HuggingFace model and tokenizer, returning a ModelHandle.
 
@@ -464,26 +468,45 @@ def load_model(
             None (default): auto-decide based on GPU memory headroom.
             True: always skip (saves memory).
             False: always snapshot (force even for large models).
+        revision: Optional Hub branch, tag, or commit passed to every loader.
+        local_files_only: Refuse network access and use only locally cached files.
     """
     _apply_deferred_shims()
 
+    if not isinstance(model_name, str) or not model_name.strip():
+        raise ValueError("model_name must be a non-empty HuggingFace identifier or local path")
+    if task not in TASK_MODEL_MAP:
+        raise ValueError(f"Unknown task {task!r}. Choose from {list(TASK_MODEL_MAP)}")
+    if quantization not in (None, "4bit", "8bit"):
+        raise ValueError(
+            "Unknown quantization {!r}. Choose None, '4bit', or '8bit'".format(quantization),
+        )
+
     dtype_map = {"float32": torch.float32, "float16": torch.float16, "bfloat16": torch.bfloat16}
     if dtype not in dtype_map:
         raise ValueError(f"Unknown dtype {dtype!r}. Choose from {list(dtype_map)}")
     torch_dtype = dtype_map[dtype]
+    resolved_device = dev.get_device(device)
+    if dtype == "bfloat16" and not dev.supports_bfloat16(resolved_device):
+        raise RuntimeError(
+            f"bfloat16 is not supported on '{resolved_device}'. Use float16 or float32.",
+        )
 
     token = _hf_token()
+    hf_kwargs = {
+        "trust_remote_code": trust_remote_code,
+        "token": token,
+        "revision": revision,
+        "local_files_only": local_files_only,
+    }
 
     try:
-        config = AutoConfig.from_pretrained(
-            model_name, trust_remote_code=trust_remote_code, token=token,
-        )
+        config = AutoConfig.from_pretrained(model_name, **hf_kwargs)
     except PermissionError:
         fallback_cache = os.path.join(tempfile.gettempdir(), "hf_home", "hub")
         os.makedirs(fallback_cache, exist_ok=True)
         config = AutoConfig.from_pretrained(
-            model_name, trust_remote_code=trust_remote_code, cache_dir=fallback_cache,
-            token=token,
+            model_name, cache_dir=fallback_cache, **hf_kwargs,
         )
     except OSError as e:
         # Gated repo access denied — provide a clear, actionable error.
@@ -525,8 +548,7 @@ def load_model(
         "pretrained_model_name_or_path": model_name,
         "config": config,
         "torch_dtype": torch_dtype,
-        "trust_remote_code": trust_remote_code,
-        "token": token,
+        **hf_kwargs,
     }
     if task == "classification":
         config.num_labels = num_labels
@@ -544,17 +566,11 @@ def load_model(
         load_kwargs["device_map"] = "auto"
     elif quantization in ("4bit", "8bit"):
         # BitsAndBytes only works on NVIDIA CUDA GPUs.
-        resolved_device = dev.get_device(device)
         if not dev.supports_bitsandbytes(resolved_device):
-            logger.warning(
-                "BitsAndBytes quantization is not supported on %s. "
-                "Loading in %s instead.",
-                resolved_device, dtype,
+            raise RuntimeError(
+                f"Quantization '{quantization}' requires an available NVIDIA CUDA device; "
+                f"resolved device was '{resolved_device}'. Remove --quantization to load in {dtype}.",
             )
-            # On MPS, load normally to the device; on CPU, fall through.
-            if resolved_device == "mps":
-                device = "mps"
-            # Don't set quantization_config — fall through to normal loading.
         else:
             try:
                 import bitsandbytes  # noqa: F401
@@ -585,7 +601,6 @@ def load_model(
 
     # device_map="auto" is only reliable on CUDA (accelerate doesn't support MPS).
     if "device_map" not in load_kwargs and device == "auto":
-        resolved_device = dev.get_device(device)
         if dev.supports_device_map_auto(resolved_device):
             load_kwargs["device_map"] = "auto"
         else:
@@ -594,6 +609,7 @@ def load_model(
 
     # Offload support: provide a folder for disk offloading when GPU memory is insufficient
     _offload_dir = None
+    _owns_offload_dir = False
     if load_kwargs.get("device_map") == "auto":
         if offload_folder:
             _offload_dir = offload_folder
@@ -602,6 +618,7 @@ def load_model(
             # Auto-create a temp offload dir so from_pretrained never crashes
             # when Accelerate needs disk offloading
             _offload_dir = tempfile.mkdtemp(prefix="obliteratus_offload_")
+            _owns_offload_dir = True
             load_kwargs["offload_folder"] = _offload_dir
             logger.info(f"Auto-created offload folder: {_offload_dir}")
 
@@ -628,6 +645,16 @@ def load_model(
 
     try:
         model = model_cls.from_pretrained(**load_kwargs)
+    except PermissionError as e:
+        # Cache dir (typically ~/.cache/huggingface) is not writable — common in
+        # containers running as UID with no home dir. Retry with /tmp cache.
+        logger.warning(
+            "PermissionError loading model (%s). Retrying with cache_dir=/tmp/hf_home/hub", e
+        )
+        fallback_cache = os.path.join(tempfile.gettempdir(), "hf_home", "hub")
+        os.makedirs(fallback_cache, exist_ok=True)
+        load_kwargs["cache_dir"] = fallback_cache
+        model = model_cls.from_pretrained(**load_kwargs)
     except OSError as e:
         err_msg = str(e)
         if "gated repo" in err_msg.lower() or "access to model" in err_msg.lower():
@@ -640,16 +667,6 @@ def load_model(
                 f"Token {'is' if token else 'is NOT'} currently set."
             ) from e
         raise
-    except PermissionError as e:
-        # Cache dir (typically ~/.cache/huggingface) is not writable — common in
-        # containers running as UID with no home dir.  Retry with /tmp cache.
-        logger.warning(
-            "PermissionError loading model (%s). Retrying with cache_dir=/tmp/hf_home/hub", e
-        )
-        fallback_cache = os.path.join(tempfile.gettempdir(), "hf_home", "hub")
-        os.makedirs(fallback_cache, exist_ok=True)
-        load_kwargs["cache_dir"] = fallback_cache
-        model = model_cls.from_pretrained(**load_kwargs)
     except (ValueError, KeyError) as e:
         err_msg = str(e)
         if "does not recognize this architecture" in err_msg or "model type" in err_msg:
@@ -667,8 +684,7 @@ def load_model(
         model = model.to(device)
     elif device == "auto" and not dev.supports_device_map_auto():
         # MPS / CPU: device_map wasn't used, move model to best device.
-        resolved = dev.get_device()
-        model = model.to(resolved)
+        model = model.to(resolved_device)
 
     model.eval()
 
@@ -676,14 +692,11 @@ def load_model(
     dev.empty_cache()
 
     try:
-        tokenizer = AutoTokenizer.from_pretrained(
-            model_name, trust_remote_code=trust_remote_code, token=token,
-        )
+        tokenizer = AutoTokenizer.from_pretrained(model_name, **hf_kwargs)
     except PermissionError:
         fallback_cache = os.path.join(tempfile.gettempdir(), "hf_home", "hub")
         tokenizer = AutoTokenizer.from_pretrained(
-            model_name, trust_remote_code=trust_remote_code, cache_dir=fallback_cache,
-            token=token,
+            model_name, cache_dir=fallback_cache, **hf_kwargs,
         )
     if tokenizer.pad_token is None:
         tokenizer.pad_token = tokenizer.eos_token
@@ -695,6 +708,7 @@ def load_model(
         model_name=model_name,
         task=task,
         _offload_dir=_offload_dir,
+        _owns_offload_dir=_owns_offload_dir,
     )
 
     # Skip snapshot for large models to avoid doubling memory usage
diff --git a/pyproject.toml b/pyproject.toml
index 64390fb..5cdf2db 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -87,7 +87,7 @@ addopts = [
     "--strict-markers",
     "--cov=obliteratus",
     "--cov-report=term-missing",
-    "--cov-fail-under=49",
+    "--cov-fail-under=55",
 ]
 filterwarnings = [
     "error",
diff --git a/scripts/check_coverage_thresholds.py b/scripts/check_coverage_thresholds.py
index 5fbd745..1d63db2 100644
--- a/scripts/check_coverage_thresholds.py
+++ b/scripts/check_coverage_thresholds.py
@@ -1,16 +1,19 @@
-"""Enforce separate line and branch floors from a coverage.py JSON report."""
+"""Enforce global, critical-file, and changed-line floors from coverage.py JSON."""
 
 from __future__ import annotations
 
 import argparse
 import json
 import math
+import re
+import subprocess
 from pathlib import Path
 from typing import Any
 
 
 def validate_coverage(
     report: dict[str, Any], *, min_line: float, min_branch: float,
+    file_floors: dict[str, float] | None = None,
 ) -> list[str]:
     """Return human-readable failures for coverage totals below their floors."""
     totals = report.get("totals")
@@ -34,14 +37,111 @@ def validate_coverage(
             failures.append(
                 f"{label} coverage {value:.2f}% is below the {minimum:.2f}% floor",
             )
+
+    files = report.get("files")
+    for path, minimum in (file_floors or {}).items():
+        if not isinstance(files, dict) or not isinstance(files.get(path), dict):
+            failures.append(f"coverage report is missing critical file {path}")
+            continue
+        summary = files[path].get("summary")
+        value = summary.get("percent_statements_covered") if isinstance(summary, dict) else None
+        if (
+            isinstance(value, bool)
+            or not isinstance(value, (int, float))
+            or not math.isfinite(value)
+        ):
+            failures.append(f"coverage report is missing numeric line coverage for {path}")
+        elif value < minimum:
+            failures.append(
+                f"critical file {path} coverage {value:.2f}% is below the {minimum:.2f}% floor",
+            )
     return failures
 
 
+_HUNK = re.compile(r"^@@ -\d+(?:,\d+)? \+(\d+)(?:,(\d+))? @@")
+
+
+def parse_changed_lines(diff: str) -> dict[str, set[int]]:
+    """Return added/modified line numbers by path from a zero-context git diff."""
+    changed: dict[str, set[int]] = {}
+    path: str | None = None
+    for line in diff.splitlines():
+        if line.startswith("+++ "):
+            marker = line[4:]
+            path = marker[2:] if marker.startswith("b/") else None
+            continue
+        match = _HUNK.match(line)
+        if path is None or match is None:
+            continue
+        start = int(match.group(1))
+        count = int(match.group(2) or "1")
+        changed.setdefault(path, set()).update(range(start, start + count))
+    return changed
+
+
+def changed_line_coverage(
+    report: dict[str, Any], changed: dict[str, set[int]],
+) -> tuple[int, int, float]:
+    """Return covered, executable, and percentage for changed measured lines."""
+    covered = 0
+    executable = 0
+    files = report.get("files", {})
+    if not isinstance(files, dict):
+        return 0, 0, 100.0
+    for path, lines in changed.items():
+        entry = files.get(path)
+        if not isinstance(entry, dict):
+            continue
+        executed = set(entry.get("executed_lines", []))
+        missing = set(entry.get("missing_lines", []))
+        measured = lines & (executed | missing)
+        executable += len(measured)
+        covered += len(measured & executed)
+    percentage = covered / executable * 100 if executable else 100.0
+    return covered, executable, percentage
+
+
+def validate_changed_coverage(
+    report: dict[str, Any], changed: dict[str, set[int]], *, minimum: float,
+) -> list[str]:
+    """Return a failure when executable changed lines miss their coverage floor."""
+    covered, executable, percentage = changed_line_coverage(report, changed)
+    if percentage < minimum:
+        return [
+            f"changed-line coverage {percentage:.2f}% ({covered}/{executable}) "
+            f"is below the {minimum:.2f}% floor",
+        ]
+    return []
+
+
+def _file_floor(value: str) -> tuple[str, float]:
+    try:
+        path, minimum = value.rsplit("=", 1)
+        if not path:
+            raise ValueError
+        return path, float(minimum)
+    except ValueError as exc:
+        raise argparse.ArgumentTypeError("expected PATH=PERCENT") from exc
+
+
 def _parser() -> argparse.ArgumentParser:
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument("report", type=Path, help="coverage.py JSON report")
     parser.add_argument("--min-line", type=float, required=True)
     parser.add_argument("--min-branch", type=float, required=True)
+    parser.add_argument(
+        "--min-file",
+        action="append",
+        default=[],
+        type=_file_floor,
+        metavar="PATH=PERCENT",
+        help="minimum statement coverage for a critical file (repeatable)",
+    )
+    parser.add_argument("--min-changed", type=float)
+    parser.add_argument(
+        "--base-ref",
+        help="git base commit/ref used to calculate changed executable lines",
+    )
     return parser
 
 
@@ -52,7 +152,34 @@ def main() -> int:
         report,
         min_line=args.min_line,
         min_branch=args.min_branch,
+        file_floors=dict(args.min_file),
     )
+    changed_result: tuple[int, int, float] | None = None
+    if args.min_changed is not None:
+        if not args.base_ref:
+            failures.append("changed-line coverage requires --base-ref")
+        else:
+            try:
+                subprocess.run(
+                    ["git", "rev-parse", "--verify", f"{args.base_ref}^{{commit}}"],
+                    check=True,
+                    capture_output=True,
+                    text=True,
+                )
+                diff = subprocess.run(
+                    ["git", "diff", "--unified=0", args.base_ref, "--", "*.py"],
+                    check=True,
+                    capture_output=True,
+                    text=True,
+                ).stdout
+            except subprocess.CalledProcessError:
+                failures.append(f"cannot calculate changed-line coverage from {args.base_ref!r}")
+            else:
+                changed = parse_changed_lines(diff)
+                changed_result = changed_line_coverage(report, changed)
+                failures.extend(
+                    validate_changed_coverage(report, changed, minimum=args.min_changed),
+                )
     if failures:
         for failure in failures:
             print(f"coverage gate failed: {failure}")
@@ -64,6 +191,11 @@ def main() -> int:
         f"line={totals['percent_statements_covered']:.2f}% "
         f"branch={totals['percent_branches_covered']:.2f}%",
     )
+    if changed_result is not None:
+        covered, executable, percentage = changed_result
+        print(
+            f"changed-line gate passed: {percentage:.2f}% ({covered}/{executable})",
+        )
     return 0
 
 
diff --git a/tests/test_cli_boundaries.py b/tests/test_cli_boundaries.py
new file mode 100644
index 0000000..d3e8987
--- /dev/null
+++ b/tests/test_cli_boundaries.py
@@ -0,0 +1,460 @@
+"""Behavioral CLI boundaries without network, accelerators, or model downloads."""
+
+from __future__ import annotations
+
+import json
+import os
+from pathlib import Path
+from types import SimpleNamespace
+from unittest.mock import MagicMock, Mock
+
+import pytest
+
+from obliteratus import cli
+
+
+def ns(**values):
+    return SimpleNamespace(**values)
+
+
+@pytest.mark.parametrize(
+    ("argv", "target"),
+    [
+        (["gpu-calc", "--params", "1"], "_cmd_gpu_calc"),
+        (["run", "config.yml"], "_cmd_run"),
+        (["interactive"], "_cmd_interactive"),
+        (["models"], "_cmd_models"),
+        (["presets"], "_cmd_presets"),
+        (["info", "local/model"], "_cmd_info"),
+        (["strategies"], "_cmd_strategies"),
+        (["report", "results.json"], "_cmd_report"),
+        (["aggregate"], "_cmd_aggregate"),
+        (["ui"], "_cmd_ui"),
+        (["recommend", "local/model"], "_cmd_recommend"),
+        (["tourney", "local/model"], "_cmd_tourney"),
+        (["self-improve", "local/model", "--audit", "audit.json", "--output-dir", "out"], "_cmd_self_improve"),
+        (["abliterate", "local/model"], "_cmd_abliterate"),
+    ],
+)
+def test_main_routes_local_commands(monkeypatch, argv, target):
+    command = Mock()
+    monkeypatch.setattr(cli, target, command)
+    cli.main(argv)
+    command.assert_called_once()
+
+
+@pytest.mark.parametrize(
+    ("argv", "target"),
+    [
+        (["run", "config.yml", "--remote", "gpu"], "_cmd_remote_run"),
+        (["tourney", "model", "--remote", "gpu"], "_cmd_remote_tourney"),
+        (["obliterate", "model", "--remote", "gpu"], "_cmd_remote_abliterate"),
+    ],
+)
+def test_main_routes_remote_commands(monkeypatch, argv, target):
+    command = Mock()
+    monkeypatch.setattr(cli, target, command)
+    cli.main(argv)
+    command.assert_called_once()
+
+
+def test_version_is_stable_and_does_not_dispatch(capsys):
+    from obliteratus import __version__
+
+    with pytest.raises(SystemExit) as exc:
+        cli.main(["--version"])
+    assert exc.value.code == 0
+    assert capsys.readouterr().out.endswith(f"obliteratus {__version__}\n")
+
+
+def test_gpu_selection_contract(monkeypatch):
+    monkeypatch.delenv("CUDA_VISIBLE_DEVICES", raising=False)
+    cli._apply_gpu_selection(ns(gpus=None, remote=None))
+    cli._apply_gpu_selection(ns(gpus="all", remote=None))
+    cli._apply_gpu_selection(ns(gpus="9", remote="host"))
+    assert "CUDA_VISIBLE_DEVICES" not in os.environ
+
+    cli._apply_gpu_selection(ns(gpus=" 2, 0 ", remote=None))
+    assert os.environ["CUDA_VISIBLE_DEVICES"] == "2,0"
+    with pytest.raises(SystemExit) as exc:
+        cli._apply_gpu_selection(ns(gpus="gpu0", remote=None))
+    assert exc.value.code == 1
+
+
+def test_ui_and_interactive_forwarding(monkeypatch):
+    import obliteratus.interactive
+    import obliteratus.local_ui
+
+    launch = Mock()
+    interactive = Mock()
+    monkeypatch.setattr(obliteratus.local_ui, "launch_local_ui", launch)
+    monkeypatch.setattr(obliteratus.interactive, "run_interactive", interactive)
+    cli._cmd_ui(ns(auth="user:pass", host="127.0.0.1", port=9000, share=True, no_browser=True, quiet=True))
+    launch.assert_called_once_with(
+        host="127.0.0.1",
+        port=9000,
+        share=True,
+        open_browser=False,
+        auth=("user", "pass"),
+        quiet=True,
+    )
+    cli._cmd_interactive()
+    interactive.assert_called_once_with()
+
+
+def test_models_presets_and_strategies_render(monkeypatch):
+    import obliteratus.presets
+    import obliteratus.strategies
+    import obliteratus.study_presets
+
+    model = ns(
+        name="Tiny",
+        hf_id="local/tiny",
+        params="1B",
+        tier="tiny",
+        recommended_dtype="float32",
+        recommended_quantization=None,
+        description="fixture",
+    )
+    preset = ns(key="quick", name="Quick", strategies=[{"name": "heads"}], max_samples=2, description="fixture")
+    strategy = type("Strategy", (), {"__doc__": "First line.\nSecond line."})
+    monkeypatch.setattr(obliteratus.presets, "list_all_presets", lambda: [model])
+    monkeypatch.setattr(obliteratus.presets, "get_presets_by_tier", lambda _tier: [model])
+    monkeypatch.setattr(obliteratus.study_presets, "list_study_presets", lambda: [preset])
+    monkeypatch.setattr(obliteratus.strategies, "STRATEGY_REGISTRY", {"fixture": strategy})
+    console = Mock()
+    monkeypatch.setattr(cli, "console", console)
+    cli._cmd_models(ns(tier=None))
+    cli._cmd_models(ns(tier="tiny"))
+    cli._cmd_presets()
+    cli._cmd_strategies()
+    assert console.print.call_count >= 8
+
+
+def test_run_local_overrides_and_remote_config(monkeypatch, tmp_path):
+    import obliteratus.config
+    import obliteratus.remote
+    import obliteratus.runner
+
+    config_path = tmp_path / "study.yml"
+    config_path.write_text("model: {name: fixture}\n")
+    config = ns(remote=None, output_dir="old")
+    monkeypatch.setattr(obliteratus.config.StudyConfig, "from_yaml", Mock(return_value=config))
+    monkeypatch.setattr(obliteratus.config.StudyConfig, "from_dict", Mock(return_value=config))
+    run = Mock()
+    monkeypatch.setattr(obliteratus.runner, "run_study", run)
+    cli._cmd_run(ns(config=str(config_path), preset="quick", output_dir="new"))
+    assert config.output_dir == "new"
+    run.assert_called_once_with(config)
+
+    config.remote = ns(
+        host="host", user="user", port=2200, ssh_key="key", remote_dir="/work",
+        python="python", sync_results=True, gpus="0",
+    )
+    runner = MagicMock()
+    runner.run_config.return_value = "/local/results"
+    monkeypatch.setattr(obliteratus.remote, "RemoteRunner", Mock(return_value=runner))
+    cli._cmd_run(ns(config=str(config_path), preset=None, output_dir=None))
+    runner.run_config.assert_called_once()
+    runner.run_config.return_value = None
+    with pytest.raises(SystemExit) as exc:
+        cli._cmd_run(ns(config=str(config_path), preset=None, output_dir=None))
+    assert exc.value.code == 1
+
+
+def test_info_prints_stable_summary(monkeypatch):
+    import obliteratus.models.loader
+
+    handle = ns(summary=lambda: {"total_params": 1234, "architecture": "fixture"})
+    load = Mock(return_value=handle)
+    monkeypatch.setattr(obliteratus.models.loader, "load_model", load)
+    console = Mock()
+    monkeypatch.setattr(cli, "console", console)
+    cli._cmd_info(ns(model="local/model", task="causal_lm", device="cpu", dtype="float32"))
+    load.assert_called_once_with(model_name="local/model", task="causal_lm", device="cpu", dtype="float32")
+    assert console.print.call_count == 3
+
+
+def test_report_success_and_plot_failure(monkeypatch, tmp_path):
+    import obliteratus.reporting.report
+
+    path = tmp_path / "results.json"
+    path.write_text(json.dumps({
+        "model_name": "fixture",
+        "baseline_metrics": {"score": 1.0},
+        "results": [{
+            "strategy": "heads", "component": "0", "description": "fixture",
+            "metrics": {"score": 0.5}, "metadata": {"source": "test"},
+        }],
+    }))
+    report = MagicMock()
+    monkeypatch.setattr(obliteratus.reporting.report, "AblationReport", Mock(return_value=report))
+    cli._cmd_report(ns(results_json=str(path), output_dir=str(tmp_path / "plots")))
+    report.add_baseline.assert_called_once_with({"score": 1.0})
+    report.add_result.assert_called_once()
+    report.plot_impact.side_effect = RuntimeError("no renderer")
+    cli._cmd_report(ns(results_json=str(path), output_dir=None))
+
+
+def test_aggregate_formats_filters_and_empty_result(monkeypatch):
+    import obliteratus.community
+
+    records = [object()]
+    aggregated = {
+        "org/model": {
+            "keep": {"n_runs": 2, "refusal_rate": {"mean": 0.1}, "perplexity": {"mean": 4.5}},
+            "drop": {"n_runs": 1},
+        },
+    }
+    monkeypatch.setattr(obliteratus.community, "load_contributions", lambda _dir: records)
+    monkeypatch.setattr(obliteratus.community, "aggregate_results", lambda _records: json.loads(json.dumps(aggregated)))
+    latex = Mock(return_value="TABLE")
+    monkeypatch.setattr(obliteratus.community, "generate_latex_table", latex)
+    cli._cmd_aggregate(ns(dir="results", min_runs=2, format="summary", metric="refusal_rate"))
+    cli._cmd_aggregate(ns(dir="results", min_runs=1, format="latex", metric="score"))
+    latex.assert_called_once()
+
+    monkeypatch.setattr(obliteratus.community, "aggregate_results", lambda _records: {"model": {"one": {"n_runs": 1}}})
+    cli._cmd_aggregate(ns(dir="results", min_runs=3, format="summary", metric="score"))
+
+
+def test_recommend_handles_config_fallback_telemetry_and_insights(monkeypatch):
+    import obliteratus.adaptive_defaults
+    import obliteratus.architecture_profiles
+    import transformers
+
+    profile = ns(
+        profile_label="Fixture", arch_class=ns(value="dense"), reasoning_class=ns(value="general"),
+        total_params_b=1.0, num_layers=2, hidden_size=8, recommended_method="advanced",
+        method_overrides={"n_directions": 2},
+    )
+    monkeypatch.setattr(transformers.AutoConfig, "from_pretrained", Mock(return_value=ns(num_hidden_layers=2, hidden_size=8)))
+    detect = Mock(return_value=profile)
+    monkeypatch.setattr(obliteratus.architecture_profiles, "detect_architecture", detect)
+    monkeypatch.setattr(obliteratus.architecture_profiles, "enhance_profile_with_telemetry", lambda p: (p, {"method": "advanced"}))
+    monkeypatch.setattr(obliteratus.adaptive_defaults, "format_recommendation", lambda _rec: "recommendation")
+    monkeypatch.setattr(obliteratus.adaptive_defaults, "get_global_insights", lambda: {
+        "total_records": 3,
+        "overall_best_methods": [{"method": "advanced", "mean_score": 0.8, "n_runs": 3}],
+        "architecture_breakdown": {"dense": {"best_method": "advanced", "best_score": 0.8, "n_methods_tested": 2, "total_runs": 3}},
+    })
+    cli._cmd_recommend(ns(model="local/model", insights=True))
+    detect.assert_called_once()
+
+    transformers.AutoConfig.from_pretrained.side_effect = OSError("offline")
+    monkeypatch.setattr(obliteratus.architecture_profiles, "enhance_profile_with_telemetry", lambda p: (p, None))
+    cli._cmd_recommend(ns(model="local/model", insights=False))
+
+
+def test_tourney_callbacks_and_winner(monkeypatch):
+    import obliteratus.tourney
+
+    result = ns(
+        winner=ns(method="advanced", score=0.9, metrics={"refusal_rate": 0.1, "coherence": 0.8}),
+        hub_repo="org/winner",
+    )
+    runner = MagicMock()
+    runner.run.return_value = result
+    factory = Mock(return_value=runner)
+    monkeypatch.setattr(obliteratus.tourney, "TourneyRunner", factory)
+    cli._cmd_tourney(ns(
+        model="model", hub_org="org", hub_repo=None, device="cpu", dtype="float32",
+        dataset="builtin", quantization=None, methods=["advanced"], output_dir="out",
+    ))
+    callbacks = factory.call_args.kwargs
+    callbacks["on_log"]("message")
+    callbacks["on_round"](ns(round_num=1, advanced_to=[1], eliminated=[2]))
+
+
+def test_gpu_calculator_validation_profile_and_moe(monkeypatch):
+    import obliteratus.model_profile
+
+    console = Mock()
+    monkeypatch.setattr(cli, "console", console)
+    cli._cmd_gpu_calc(ns(model=None, params=10.0, active_params=2.0, dtype="float16", gpu_mem=24.0))
+    profile = ns(total_params_b=7.0, active_params_b=3.0)
+    monkeypatch.setattr(obliteratus.model_profile, "profile_model", Mock(return_value=profile))
+    cli._cmd_gpu_calc(ns(model="local/model", params=None, active_params=None, dtype="int8", gpu_mem=16.0))
+
+    with pytest.raises(SystemExit):
+        cli._cmd_gpu_calc(ns(model=None, params=None, active_params=None, dtype="float16", gpu_mem=16.0))
+    with pytest.raises(SystemExit):
+        cli._cmd_gpu_calc(ns(model=None, params=1.0, active_params=None, dtype="float16", gpu_mem=1.0))
+    monkeypatch.setattr(obliteratus.model_profile, "profile_model", Mock(side_effect=OSError("offline")))
+    with pytest.raises(SystemExit):
+        cli._cmd_gpu_calc(ns(model="x", params=None, active_params=None, dtype="float16", gpu_mem=16.0))
+
+
+def test_parameter_estimators_cover_dense_moe_and_invalid():
+    assert cli._estimate_total_params_b(ns(num_parameters=2_000_000_000)) == 2.0
+    dense = ns(hidden_size=128, num_hidden_layers=2, vocab_size=1000, intermediate_size=512)
+    total = cli._estimate_total_params_b(dense)
+    assert total > 0
+    assert cli._estimate_active_params_b(dense, total) == total
+    moe = ns(
+        hidden_size=4096, num_hidden_layers=32, vocab_size=100_000, intermediate_size=14_336,
+        moe_intermediate_size=2048, num_local_experts=8, num_experts_per_tok=2,
+    )
+    moe_total = cli._estimate_total_params_b(moe)
+    assert 0.1 <= cli._estimate_active_params_b(moe, moe_total) < moe_total
+    with pytest.raises(SystemExit):
+        cli._estimate_total_params_b(ns(hidden_size=0, num_hidden_layers=0, vocab_size=0))
+
+
+def _remote_args(**overrides):
+    values = {
+        "remote": "user@host", "ssh_port": 22, "ssh_key": None, "remote_dir": "/work",
+        "remote_python": "python3", "no_sync": False, "gpus": "0", "model": "model",
+        "output_dir": "out", "method": "advanced", "device": "cuda", "dtype": "float16",
+        "quantization": "4bit", "n_directions": 2, "direction_method": "svd",
+        "regularization": 0.2, "refinement_passes": 2, "min_layer_fraction": 0.1,
+        "max_layer_fraction": 0.9, "harmless_pc_count": 1, "shield_concept_count": 2,
+        "shield_ridge": 0.1, "shield_residualize": True, "shield_layer_penalty": 0.2,
+        "projection_target": "all", "projection_row_fraction": 0.5, "large_model": True,
+        "verify_sample_size": 5, "config": "config.yml", "preset": "quick", "methods": ["advanced"],
+        "hub_org": "org", "hub_repo": None, "dataset": "builtin",
+    }
+    values.update(overrides)
+    return ns(**values)
+
+
+def test_remote_runner_factory_and_commands(monkeypatch):
+    import obliteratus.remote
+
+    config = object()
+    runner = MagicMock()
+    monkeypatch.setattr(obliteratus.remote.RemoteConfig, "from_cli_args", Mock(return_value=config))
+    monkeypatch.setattr(obliteratus.remote, "RemoteRunner", Mock(return_value=runner))
+    args = _remote_args()
+    assert cli._make_remote_runner(args) is runner
+
+    monkeypatch.setattr(cli, "_make_remote_runner", lambda _args: runner)
+    runner.run_obliterate.return_value = "results"
+    cli._cmd_remote_abliterate(args)
+    assert runner.run_obliterate.call_args.kwargs["projection_row_fraction"] == 0.5
+    runner.run_config.return_value = "results"
+    cli._cmd_remote_run(args)
+    runner.run_tourney.return_value = "results"
+    cli._cmd_remote_tourney(args)
+
+    runner.run_obliterate.return_value = None
+    with pytest.raises(SystemExit):
+        cli._cmd_remote_abliterate(args)
+    runner.run_config.return_value = None
+    with pytest.raises(SystemExit):
+        cli._cmd_remote_run(args)
+    runner.run_tourney.return_value = None
+    with pytest.raises(SystemExit):
+        cli._cmd_remote_tourney(args)
+
+
+def test_abliterate_pipeline_callbacks_residue_and_contribution(monkeypatch, tmp_path):
+    import obliteratus.abliterate
+    import obliteratus.community
+    import obliteratus.hard_negative
+    import obliteratus.telemetry
+    import rich.live
+
+    stages = [ns(key=f"s{i}", name=f"Stage {i}") for i in range(6)]
+    monkeypatch.setattr(obliteratus.abliterate, "STAGES", stages)
+    monkeypatch.setattr(obliteratus.abliterate, "METHODS", {"advanced": {"label": "Advanced"}})
+    monkeypatch.setattr(
+        obliteratus.hard_negative,
+        "build_weighted_prompt_pairs",
+        lambda **_kwargs: (["harm"], ["safe"], {"residue_examples": 1, "residue_added_pairs": 2, "total_pairs": 3}),
+    )
+    monkeypatch.setattr(obliteratus.community, "save_contribution", lambda *_args, **_kwargs: "contribution.json")
+    telemetry = Mock()
+    monkeypatch.setattr(obliteratus.telemetry, "maybe_send_pipeline_report", telemetry)
+
+    result_path = tmp_path / "result"
+    result_path.mkdir()
+    pipeline = MagicMock()
+
+    def run():
+        kwargs = factory.call_args.kwargs
+        kwargs["on_log"]("working")
+        kwargs["on_stage"](ns(stage="s0", status="running", message="work"))
+        kwargs["on_stage"](ns(stage="s0", status="done", message="done"))
+        return str(result_path)
+
+    pipeline.run.side_effect = run
+    factory = Mock(return_value=pipeline)
+    monkeypatch.setattr(obliteratus.abliterate, "AbliterationPipeline", factory)
+
+    class FakeLive:
+        def __init__(self, *_args, **_kwargs):
+            self.update = Mock()
+
+        def __enter__(self):
+            return self
+
+        def __exit__(self, *_args):
+            return False
+
+    monkeypatch.setattr(rich.live, "Live", FakeLive)
+    args = ns(
+        model="org/model", output_dir=None, device="cpu", dtype="float32", method="advanced",
+        n_directions=2, direction_method="svd", regularization=0.2, refinement_passes=1,
+        min_layer_fraction=0.1, max_layer_fraction=0.9, harmless_pc_count=1,
+        shield_concept_count=2, shield_ridge=0.1, shield_residualize=True,
+        shield_layer_penalty=0.2, projection_target="all", projection_row_fraction=0.5,
+        quantization=None, large_model=False, verify_sample_size=3,
+        residue_file=["audit.json"], dataset="builtin", residue_weight=2, residue_max=4,
+        contribute=True, contribute_notes="fixture",
+    )
+    cli._cmd_abliterate(args)
+    assert (result_path / "hard_negative_residue.json").is_file()
+    telemetry.assert_called_once_with(pipeline)
+
+
+def test_self_improve_dry_run_and_pipeline(monkeypatch, tmp_path):
+    import obliteratus.abliterate
+    import obliteratus.hard_negative
+    import obliteratus.model_profile
+
+    profile = ns(
+        total_params_b=1.0, total_params=1_000_000_000, active_params_b=1.0,
+        source="fixture", num_layers=2, hidden_size=8,
+        to_json=lambda: {
+            "model_id": "model", "total_params": 1_000_000_000, "total_params_b": 1.0,
+            "active_params_b": 1.0, "num_layers": 2, "hidden_size": 8, "source": "fixture",
+        },
+    )
+    monkeypatch.setattr(obliteratus.model_profile, "profile_model", lambda *_args, **_kwargs: profile)
+    monkeypatch.setattr(obliteratus.model_profile, "default_self_improve_params", lambda _profile: {
+        "n_directions": 2, "regularization": 0.2, "refinement_passes": 1,
+        "residue_weight": 3, "verify_sample_size": 5, "note": "fixture",
+    })
+    monkeypatch.setattr(obliteratus.hard_negative, "load_residue_file", lambda _path: ["residue"])
+    def save_residue(_items, path):
+        path = Path(path)
+        path.parent.mkdir(parents=True, exist_ok=True)
+        path.write_text("[]")
+
+    monkeypatch.setattr(obliteratus.hard_negative, "save_residue_file", save_residue)
+    monkeypatch.setattr(obliteratus.hard_negative, "build_weighted_prompt_pairs", lambda **_kwargs: (
+        ["harm"], ["safe"], {"residue_examples": 1, "residue_added_pairs": 3, "total_pairs": 4},
+    ))
+    output = tmp_path / "out"
+    args = ns(
+        model="model", dtype="float32", params_b=None, no_param_auto_scale=False,
+        n_directions=None, regularization=None, refinement_passes=None, residue_weight=None,
+        verify_sample_size=None, audit=["audit.json"], residue_out=None, output_dir=str(output),
+        dataset="builtin", residue_max=None, projection_row_fraction=None, method="advanced",
+        direction_method="svd", min_layer_fraction=None, max_layer_fraction=None,
+        harmless_pc_count=None, shield_concept_count=None, shield_ridge=None,
+        shield_residualize=None, shield_layer_penalty=None, projection_target=None,
+        device="cpu", dry_run=True,
+    )
+    cli._cmd_self_improve(args)
+    assert (output / "self_improve_plan.json").is_file()
+
+    result = tmp_path / "candidate"
+    result.mkdir()
+    pipeline = MagicMock()
+    pipeline.run.return_value = str(result)
+    monkeypatch.setattr(obliteratus.abliterate, "AbliterationPipeline", Mock(return_value=pipeline))
+    args.dry_run = False
+    cli._cmd_self_improve(args)
+    assert (result / "hard_negative_residue.json").is_file()
diff --git a/tests/test_coverage_thresholds.py b/tests/test_coverage_thresholds.py
index 8754421..9280b0c 100644
--- a/tests/test_coverage_thresholds.py
+++ b/tests/test_coverage_thresholds.py
@@ -13,35 +13,42 @@ MODULE = importlib.util.module_from_spec(SPEC)
 SPEC.loader.exec_module(MODULE)
 
 
-def _report(line: float = 49.0, branch: float = 36.0) -> dict[str, object]:
+def _report(line: float = 55.0, branch: float = 42.0) -> dict[str, object]:
     return {
         "totals": {
             "percent_statements_covered": line,
             "percent_branches_covered": branch,
         },
+        "files": {
+            "obliteratus/example.py": {
+                "summary": {"percent_statements_covered": 70.0},
+                "executed_lines": [1, 2, 4],
+                "missing_lines": [3],
+            },
+        },
     }
 
 
 def test_validate_coverage_accepts_exact_floors():
     assert MODULE.validate_coverage(
-        _report(), min_line=49.0, min_branch=36.0,
+        _report(), min_line=55.0, min_branch=42.0,
     ) == []
 
 
 def test_validate_coverage_reports_each_regression():
     failures = MODULE.validate_coverage(
-        _report(line=48.9, branch=35.9), min_line=49.0, min_branch=36.0,
+        _report(line=54.9, branch=41.9), min_line=55.0, min_branch=42.0,
     )
 
     assert failures == [
-        "line coverage 48.90% is below the 49.00% floor",
-        "branch coverage 35.90% is below the 36.00% floor",
+        "line coverage 54.90% is below the 55.00% floor",
+        "branch coverage 41.90% is below the 42.00% floor",
     ]
 
 
 def test_validate_coverage_rejects_malformed_totals():
     assert MODULE.validate_coverage(
-        {}, min_line=49.0, min_branch=36.0,
+        {}, min_line=55.0, min_branch=42.0,
     ) == ["coverage report is missing the totals object"]
 
 
@@ -51,8 +58,56 @@ def test_validate_coverage_rejects_non_numeric_metrics():
     report["totals"]["percent_branches_covered"] = float("nan")
 
     assert MODULE.validate_coverage(
-        report, min_line=49.0, min_branch=36.0,
+        report, min_line=55.0, min_branch=42.0,
     ) == [
         "coverage report is missing numeric percent_statements_covered",
         "coverage report is missing numeric percent_branches_covered",
     ]
+
+
+def test_validate_coverage_enforces_critical_file_floors():
+    assert MODULE.validate_coverage(
+        _report(),
+        min_line=55.0,
+        min_branch=42.0,
+        file_floors={"obliteratus/example.py": 70.0},
+    ) == []
+
+    report = _report()
+    report["files"]["obliteratus/example.py"]["summary"]["percent_statements_covered"] = 69.9
+    assert MODULE.validate_coverage(
+        report,
+        min_line=55.0,
+        min_branch=42.0,
+        file_floors={"obliteratus/example.py": 70.0, "missing.py": 70.0},
+    ) == [
+        "critical file obliteratus/example.py coverage 69.90% is below the 70.00% floor",
+        "coverage report is missing critical file missing.py",
+    ]
+
+
+def test_parse_changed_lines_and_measurement_ignore_non_executable_lines():
+    diff = """diff --git a/obliteratus/example.py b/obliteratus/example.py
++++ b/obliteratus/example.py
+@@ -1,2 +1,4 @@
+diff --git a/tests/test_example.py b/tests/test_example.py
++++ b/tests/test_example.py
+@@ -0,0 +1,2 @@
+"""
+    changed = MODULE.parse_changed_lines(diff)
+    assert changed == {
+        "obliteratus/example.py": {1, 2, 3, 4},
+        "tests/test_example.py": {1, 2},
+    }
+    assert MODULE.changed_line_coverage(_report(), changed) == (3, 4, 75.0)
+    assert MODULE.validate_changed_coverage(
+        _report(), changed, minimum=90.0,
+    ) == ["changed-line coverage 75.00% (3/4) is below the 90.00% floor"]
+
+
+def test_changed_line_gate_passes_when_diff_has_no_measured_source():
+    assert MODULE.changed_line_coverage(_report(), {"tests/test_example.py": {1}}) == (
+        0,
+        0,
+        100.0,
+    )
diff --git a/tests/test_device_boundaries.py b/tests/test_device_boundaries.py
new file mode 100644
index 0000000..e4ea711
--- /dev/null
+++ b/tests/test_device_boundaries.py
@@ -0,0 +1,209 @@
+"""Deterministic contracts for accelerator detection and fallback behavior."""
+
+from __future__ import annotations
+
+from types import SimpleNamespace
+from unittest.mock import Mock
+
+import pytest
+import torch
+
+from obliteratus import device
+
+
+@pytest.mark.parametrize(
+    ("cuda", "mps", "expected"),
+    [(True, False, "cuda"), (False, True, "mps"), (False, False, "cpu")],
+)
+def test_auto_device_preference(monkeypatch, cuda, mps, expected):
+    monkeypatch.setattr(device, "is_cuda", lambda: cuda)
+    monkeypatch.setattr(device, "is_mps", lambda: mps)
+    assert device.get_device() == expected
+    assert device.is_gpu_available() is (cuda or mps)
+
+
+def test_explicit_device_validation(monkeypatch):
+    monkeypatch.setattr(device, "is_cuda", lambda: False)
+    monkeypatch.setattr(device, "is_mps", lambda: False)
+
+    assert device.get_device("cpu") == "cpu"
+    with pytest.raises(RuntimeError, match="CUDA was requested.*device='auto'"):
+        device.get_device("cuda:0")
+    with pytest.raises(RuntimeError, match="MPS was requested.*device='auto'"):
+        device.get_device("mps")
+    with pytest.raises(ValueError, match="Unknown device 'tpu'"):
+        device.get_device("tpu")
+    with pytest.raises(ValueError, match="Unknown device 'cuda:gpu'"):
+        device.get_device("cuda:gpu")
+
+    monkeypatch.setattr(device, "is_cuda", lambda: True)
+    assert device.get_device("cuda") == "cuda"
+    assert device.get_device("cuda:3") == "cuda:3"
+    monkeypatch.setattr(device, "is_mps", lambda: True)
+    assert device.get_device("mps") == "mps"
+
+
+def test_names_and_device_counts(monkeypatch):
+    monkeypatch.setattr(device, "is_cuda", lambda: True)
+    monkeypatch.setattr(device.torch.cuda, "get_device_name", lambda _index: "Test GPU")
+    monkeypatch.setattr(device.torch.cuda, "device_count", lambda: 4)
+    assert device.get_device_name() == "Test GPU"
+    assert device.device_count() == 4
+
+    monkeypatch.setattr(device, "is_cuda", lambda: False)
+    monkeypatch.setattr(device, "is_mps", lambda: True)
+    monkeypatch.setattr(device.platform, "processor", lambda: "M3")
+    assert device.get_device_name() == "Apple M3 (MPS)"
+    assert device.device_count() == 1
+
+    monkeypatch.setattr(device, "is_mps", lambda: False)
+    assert device.get_device_name() == "CPU"
+    assert device.device_count() == 0
+
+
+def test_system_memory_sources_and_fallback(monkeypatch):
+    gib = 1024**3
+    fake_psutil = SimpleNamespace(
+        virtual_memory=lambda: SimpleNamespace(total=32 * gib, available=12 * gib),
+    )
+    monkeypatch.setitem(__import__("sys").modules, "psutil", fake_psutil)
+    assert device._system_memory_gb() == (32.0, 12.0)
+
+    monkeypatch.delitem(__import__("sys").modules, "psutil", raising=False)
+    real_import = __import__("builtins").__import__
+
+    def reject_psutil(name, *args, **kwargs):
+        if name == "psutil":
+            raise ImportError
+        return real_import(name, *args, **kwargs)
+
+    monkeypatch.setattr("builtins.__import__", reject_psutil)
+    monkeypatch.setattr(device.os, "sysconf", lambda name: {"SC_PHYS_PAGES": 4, "SC_PAGE_SIZE": gib}[name])
+    assert device._system_memory_gb() == (4.0, 2.4)
+
+    monkeypatch.setattr(device.os, "sysconf", Mock(side_effect=ValueError))
+    assert device._system_memory_gb() == (16.0, 8.0)
+
+
+def test_memory_info_for_cuda_and_cuda_fallback(monkeypatch):
+    gib = 1024**3
+    monkeypatch.setattr(device, "is_cuda", lambda: True)
+    monkeypatch.setattr(device, "get_device_name", lambda: "GPU")
+    monkeypatch.setattr(device.torch.cuda, "mem_get_info", lambda _index: (6 * gib, 8 * gib))
+    monkeypatch.setattr(device.torch.cuda, "memory_allocated", lambda _index: 1 * gib)
+    monkeypatch.setattr(device.torch.cuda, "memory_reserved", lambda _index: 2 * gib)
+    assert device.get_memory_info(2) == device.MemoryInfo(1, 2, 8, 6, "GPU")
+
+    monkeypatch.setattr(device.torch.cuda, "mem_get_info", Mock(side_effect=RuntimeError("unsupported")))
+    monkeypatch.setattr(
+        device.torch.cuda,
+        "get_device_properties",
+        lambda _index: SimpleNamespace(total_memory=10 * gib),
+    )
+    assert device.get_memory_info(2) == device.MemoryInfo(total_gb=10, free_gb=10, device_name="GPU")
+
+
+def test_memory_info_for_mps_cpu_and_total_free(monkeypatch):
+    monkeypatch.setattr(device, "is_cuda", lambda: False)
+    monkeypatch.setattr(device, "is_mps", lambda: True)
+    monkeypatch.setattr(device, "get_device_name", lambda: "MPS")
+    monkeypatch.setattr(device, "_system_memory_gb", lambda: (20.0, 8.0))
+    assert device.get_memory_info() == device.MemoryInfo(6, 0, 14, 8, "MPS")
+    assert device.get_total_free_gb() == pytest.approx(5.6)
+
+    monkeypatch.setattr(device, "is_mps", lambda: False)
+    monkeypatch.setattr(device, "get_device_name", lambda: "CPU")
+    assert device.get_memory_info() == device.MemoryInfo(total_gb=20, free_gb=8, device_name="CPU")
+    assert device.get_total_free_gb() == 0
+
+
+def test_total_cuda_memory_sums_query_and_fallback(monkeypatch):
+    gib = 1024**3
+    monkeypatch.setattr(device, "is_cuda", lambda: True)
+    monkeypatch.setattr(device.torch.cuda, "device_count", lambda: 2)
+    monkeypatch.setattr(
+        device.torch.cuda,
+        "mem_get_info",
+        Mock(side_effect=[(3 * gib, 4 * gib), RuntimeError("no query")]),
+    )
+    monkeypatch.setattr(
+        device.torch.cuda,
+        "get_device_properties",
+        lambda _index: SimpleNamespace(total_memory=5 * gib),
+    )
+    assert device.get_total_free_gb() == 8.0
+
+
+def test_cache_cleanup_paths_are_best_effort(monkeypatch):
+    cuda_empty = Mock()
+    monkeypatch.setattr(device, "is_cuda", lambda: True)
+    monkeypatch.setattr(device.torch.cuda, "empty_cache", cuda_empty)
+    device.empty_cache()
+    cuda_empty.assert_called_once_with()
+
+    sync = Mock()
+    reset = Mock()
+    monkeypatch.setattr(device.torch.cuda, "empty_cache", Mock(side_effect=RuntimeError("busy")))
+    monkeypatch.setattr(device.torch.cuda, "synchronize", sync)
+    monkeypatch.setattr(device.torch.cuda, "reset_peak_memory_stats", reset)
+    monkeypatch.setattr(device.gc, "collect", Mock())
+    device.free_gpu_memory()
+    sync.assert_called_once_with()
+    reset.assert_called_once_with()
+
+    mps_empty = Mock()
+    mps_sync = Mock(side_effect=RuntimeError("busy"))
+    monkeypatch.setattr(device, "is_cuda", lambda: False)
+    monkeypatch.setattr(device, "is_mps", lambda: True)
+    monkeypatch.setattr(device.torch, "mps", SimpleNamespace(empty_cache=mps_empty, synchronize=mps_sync))
+    device.empty_cache()
+    mps_empty.side_effect = RuntimeError("busy")
+    device.free_gpu_memory()
+    assert mps_empty.call_count == 2
+    mps_sync.assert_called_once_with()
+
+
+def test_seed_dtype_and_capability_contracts(monkeypatch):
+    manual_seed = Mock()
+    cuda_seed = Mock()
+    monkeypatch.setattr(device.torch, "manual_seed", manual_seed)
+    monkeypatch.setattr(device.torch.cuda, "manual_seed_all", cuda_seed)
+    monkeypatch.setattr(device, "is_cuda", lambda: True)
+    device.set_seed_all(7)
+    manual_seed.assert_called_once_with(7)
+    cuda_seed.assert_called_once_with(7)
+
+    assert device.default_dtype("cpu") is torch.float32
+    assert device.default_dtype("cuda") is torch.float16
+    monkeypatch.setattr(device.torch.cuda, "get_device_capability", lambda _index: (8, 0))
+    assert device.supports_bfloat16("cuda") is True
+    monkeypatch.setattr(device.torch.cuda, "get_device_capability", lambda _index: (7, 5))
+    assert device.supports_bfloat16("cuda") is False
+    monkeypatch.setattr(device, "is_cuda", lambda: False)
+    assert device.supports_bfloat16("cuda") is False
+    assert device.supports_bfloat16("cpu") is True
+    assert device.supports_float64("mps") is False
+    assert device.supports_float64("cpu") is True
+    assert device.supports_bitsandbytes("cuda:1") is True
+    assert device.supports_bitsandbytes("mps") is False
+    assert device.supports_device_map_auto("cuda") is True
+    assert device.supports_device_map_auto("cpu") is False
+
+
+def test_svd_dtype_and_oom_matching():
+    assert device.safe_svd_dtype(torch.ones(1, dtype=torch.float64)) is torch.float64
+    assert device.safe_svd_dtype(torch.ones(1, dtype=torch.float16)) is torch.float32
+    assert device.is_oom_error(torch.cuda.OutOfMemoryError("oom")) is True
+    assert device.is_oom_error(RuntimeError("MPS backend out of memory")) is True
+    assert device.is_oom_error(RuntimeError("other")) is False
+
+
+def test_configure_cuda_allocator(monkeypatch):
+    monkeypatch.delenv("PYTORCH_CUDA_ALLOC_CONF", raising=False)
+    monkeypatch.setattr(device, "is_cuda", lambda: True)
+    device.configure_cuda_alloc()
+    assert device.os.environ["PYTORCH_CUDA_ALLOC_CONF"] == "expandable_segments:True"
+
+    monkeypatch.setenv("PYTORCH_CUDA_ALLOC_CONF", "existing")
+    device.configure_cuda_alloc()
+    assert device.os.environ["PYTORCH_CUDA_ALLOC_CONF"] == "existing"
diff --git a/tests/test_loader_boundaries.py b/tests/test_loader_boundaries.py
new file mode 100644
index 0000000..c997418
--- /dev/null
+++ b/tests/test_loader_boundaries.py
@@ -0,0 +1,354 @@
+"""Offline model-loader contracts at provider, device, and quantization boundaries."""
+
+from __future__ import annotations
+
+import builtins
+from types import SimpleNamespace
+from unittest.mock import MagicMock, Mock
+
+import pytest
+import torch
+
+from obliteratus.models import loader
+
+
+def _config(**overrides):
+    values = {
+        "model_type": "gpt2",
+        "architectures": ["GPT2LMHeadModel"],
+        "num_hidden_layers": 2,
+        "num_attention_heads": 4,
+        "hidden_size": 8,
+        "intermediate_size": 16,
+        "vocab_size": 32,
+        "quantization_config": None,
+    }
+    values.update(overrides)
+    return SimpleNamespace(**values)
+
+
+def _model():
+    model = MagicMock()
+    model.to.return_value = model
+    model.state_dict.return_value = {"weight": torch.ones(2)}
+    model.parameters.return_value = iter([torch.ones(2), torch.ones(3)])
+    return model
+
+
+@pytest.fixture
+def loader_boundary(monkeypatch):
+    config = _config()
+    model = _model()
+    tokenizer = SimpleNamespace(pad_token=None, eos_token="<eos>")
+    model_class = SimpleNamespace(from_pretrained=Mock(return_value=model))
+    monkeypatch.setattr(loader.AutoConfig, "from_pretrained", Mock(return_value=config))
+    monkeypatch.setattr(loader.AutoTokenizer, "from_pretrained", Mock(return_value=tokenizer))
+    monkeypatch.setitem(loader.TASK_MODEL_MAP, "causal_lm", model_class)
+    monkeypatch.setitem(loader.TASK_MODEL_MAP, "classification", model_class)
+    monkeypatch.setattr(loader.dev, "get_device", lambda preference="auto": "cpu" if preference == "auto" else preference)
+    monkeypatch.setattr(loader.dev, "supports_device_map_auto", lambda _device=None: False)
+    monkeypatch.setattr(loader.dev, "supports_bitsandbytes", lambda _device=None: False)
+    monkeypatch.setattr(loader.dev, "supports_bfloat16", lambda _device=None: True)
+    monkeypatch.setattr(loader.dev, "get_total_free_gb", lambda: 0.0)
+    monkeypatch.setattr(loader.dev, "empty_cache", Mock())
+    monkeypatch.setattr(loader.dev, "is_cuda", lambda: False)
+    return SimpleNamespace(config=config, model=model, tokenizer=tokenizer, model_class=model_class)
+
+
+@pytest.mark.parametrize(
+    ("kwargs", "message"),
+    [
+        ({"model_name": ""}, "model_name must be"),
+        ({"model_name": "x", "task": "embedding"}, "Unknown task"),
+        ({"model_name": "x", "dtype": "int9"}, "Unknown dtype"),
+        ({"model_name": "x", "quantization": "3bit"}, "Unknown quantization"),
+    ],
+)
+def test_invalid_requests_fail_before_provider_access(loader_boundary, monkeypatch, kwargs, message):
+    config_load = Mock(side_effect=AssertionError("provider should not be called"))
+    monkeypatch.setattr(loader.AutoConfig, "from_pretrained", config_load)
+    with pytest.raises(ValueError, match=message):
+        loader.load_model(**kwargs)
+    config_load.assert_not_called()
+
+
+def test_revision_trust_and_offline_flags_reach_every_provider(loader_boundary):
+    handle = loader.load_model(
+        "local/model",
+        revision="deadbeef",
+        trust_remote_code=True,
+        local_files_only=True,
+        skip_snapshot=True,
+    )
+    expected = {
+        "trust_remote_code": True,
+        "token": None,
+        "revision": "deadbeef",
+        "local_files_only": True,
+    }
+    loader.AutoConfig.from_pretrained.assert_called_once_with("local/model", **expected)
+    loader_boundary.model_class.from_pretrained.assert_called_once()
+    for key, value in expected.items():
+        assert loader_boundary.model_class.from_pretrained.call_args.kwargs[key] == value
+    loader.AutoTokenizer.from_pretrained.assert_called_once_with("local/model", **expected)
+    assert handle.tokenizer.pad_token == "<eos>"
+    loader_boundary.model.eval.assert_called_once_with()
+    loader.dev.empty_cache.assert_called_once_with()
+
+
+def test_hf_token_is_forwarded_without_logging_value(loader_boundary, monkeypatch):
+    monkeypatch.setenv("HF_TOKEN", "secret-token")
+    loader.load_model("x", skip_snapshot=True)
+    assert loader.AutoConfig.from_pretrained.call_args.kwargs["token"] == "secret-token"
+    assert loader_boundary.model_class.from_pretrained.call_args.kwargs["token"] == "secret-token"
+    assert loader.AutoTokenizer.from_pretrained.call_args.kwargs["token"] == "secret-token"
+
+
+def test_device_and_dtype_failures_precede_provider_access(loader_boundary, monkeypatch):
+    provider = Mock(side_effect=AssertionError("provider should not be called"))
+    monkeypatch.setattr(loader.AutoConfig, "from_pretrained", provider)
+    monkeypatch.setattr(loader.dev, "get_device", Mock(side_effect=RuntimeError("CUDA unavailable")))
+    with pytest.raises(RuntimeError, match="CUDA unavailable"):
+        loader.load_model("x", device="cuda")
+    provider.assert_not_called()
+
+    monkeypatch.setattr(loader.dev, "get_device", lambda _preference="auto": "mps")
+    monkeypatch.setattr(loader.dev, "supports_bfloat16", lambda _device=None: False)
+    with pytest.raises(RuntimeError, match="bfloat16 is not supported on 'mps'"):
+        loader.load_model("x", device="mps", dtype="bfloat16")
+    provider.assert_not_called()
+
+
+def test_config_permission_error_retries_in_temp_cache(loader_boundary, monkeypatch, tmp_path):
+    monkeypatch.setattr(loader.tempfile, "gettempdir", lambda: str(tmp_path))
+    loader.AutoConfig.from_pretrained.side_effect = [PermissionError("cache"), loader_boundary.config]
+    loader.load_model("x", skip_snapshot=True)
+    assert loader.AutoConfig.from_pretrained.call_count == 2
+    assert loader.AutoConfig.from_pretrained.call_args.kwargs["cache_dir"] == str(tmp_path / "hf_home" / "hub")
+    assert (tmp_path / "hf_home" / "hub").is_dir()
+
+
+@pytest.mark.parametrize("message", ["Gated repo denied", "Access to model is restricted"])
+def test_config_gated_repo_failure_is_actionable(loader_boundary, monkeypatch, message):
+    loader.AutoConfig.from_pretrained.side_effect = OSError(message)
+    with pytest.raises(RuntimeError, match=r"(?s)Accept the license.*HF_TOKEN"):
+        loader.load_model("owner/gated", skip_snapshot=True)
+
+
+def test_non_gated_config_oserror_is_preserved(loader_boundary):
+    loader.AutoConfig.from_pretrained.side_effect = OSError("offline cache miss")
+    with pytest.raises(OSError, match="offline cache miss"):
+        loader.load_model("x", local_files_only=True)
+
+
+@pytest.mark.parametrize("exc", [ValueError("unknown"), KeyError("model_type")])
+def test_malformed_or_unknown_config_has_stable_guidance(loader_boundary, exc):
+    loader.AutoConfig.from_pretrained.side_effect = exc
+    with pytest.raises(RuntimeError, match=r"(?s)not recognized by transformers.*trust_remote_code=True"):
+        loader.load_model("new/model")
+
+
+def test_task_model_selection_and_gemma_contract(monkeypatch):
+    causal = object()
+    classification = object()
+    image_text = object()
+    monkeypatch.setitem(loader.TASK_MODEL_MAP, "causal_lm", causal)
+    monkeypatch.setitem(loader.TASK_MODEL_MAP, "classification", classification)
+    monkeypatch.setattr(loader, "AutoModelForImageTextToText", image_text)
+    assert loader._select_model_class("causal_lm", _config()) is causal
+    assert loader._select_model_class("classification", _config()) is classification
+    assert loader._select_model_class("causal_lm", _config(model_type="gemma4")) is image_text
+    assert loader._select_model_class(
+        "causal_lm",
+        _config(model_type="unknown", architectures=["Gemma4ForConditionalGeneration"]),
+    ) is image_text
+    monkeypatch.setattr(loader, "AutoModelForImageTextToText", None)
+    with pytest.raises(RuntimeError, match="Upgrade transformers"):
+        loader._select_model_class("causal_lm", _config(model_type="gemma4"))
+    with pytest.raises(ValueError, match="Unknown task"):
+        loader._select_model_class("embedding", _config())
+
+
+def test_model_handle_metadata_snapshot_restore_summary_and_cleanup(tmp_path):
+    model = _model()
+    nested = SimpleNamespace(
+        num_hidden_layers=3,
+        num_attention_heads=6,
+        hidden_size=12,
+        intermediate_size=24,
+    )
+    config = _config(
+        num_hidden_layers=0,
+        num_attention_heads=0,
+        hidden_size=0,
+        intermediate_size=0,
+        text_config=nested,
+    )
+    offload = tmp_path / "offload"
+    offload.mkdir()
+    (offload / "weight").write_text("x")
+    handle = loader.ModelHandle(
+        model,
+        SimpleNamespace(),
+        config,
+        "x",
+        "causal_lm",
+        _offload_dir=str(offload),
+        _owns_offload_dir=True,
+    )
+    assert (handle.num_layers, handle.num_heads, handle.hidden_size, handle.intermediate_size) == (3, 6, 12, 24)
+    with pytest.raises(RuntimeError, match="call .snapshot"):
+        handle.restore()
+    handle.snapshot()
+    handle.restore()
+    model.load_state_dict.assert_called_once()
+    assert handle.summary() == {
+        "model_name": "x",
+        "architecture": "gpt2",
+        "task": "causal_lm",
+        "num_layers": 3,
+        "num_heads": 6,
+        "hidden_size": 12,
+        "intermediate_size": 24,
+        "total_params": 5,
+    }
+    handle.cleanup()
+    assert not offload.exists()
+    assert handle._offload_dir is None
+
+
+def test_model_memory_estimation_handles_dense_moe_nested_and_unknown():
+    dense = loader._estimate_model_memory_gb(_config(), torch.float32)
+    moe = loader._estimate_model_memory_gb(_config(num_local_experts=4), torch.float32)
+    assert dense > 0
+    assert moe > dense
+    nested = _config(hidden_size=0, num_hidden_layers=0, intermediate_size=0, vocab_size=0)
+    nested.text_config = _config(hidden_size=8, num_hidden_layers=2, intermediate_size=16, vocab_size=32)
+    assert loader._estimate_model_memory_gb(nested, torch.float16) > 0
+    assert loader._estimate_model_memory_gb(_config(hidden_size=0), torch.float16) == 0
+
+
+@pytest.mark.parametrize("quantization", ["4bit", "8bit"])
+def test_quantization_rejects_non_cuda_instead_of_silent_degradation(loader_boundary, quantization):
+    with pytest.raises(RuntimeError, match="requires an available NVIDIA CUDA device"):
+        loader.load_model("x", quantization=quantization)
+    loader_boundary.model_class.from_pretrained.assert_not_called()
+
+
+def test_quantization_requires_bitsandbytes(loader_boundary, monkeypatch):
+    monkeypatch.setattr(loader.dev, "get_device", lambda _preference="auto": "cuda")
+    monkeypatch.setattr(loader.dev, "supports_bitsandbytes", lambda _device=None: True)
+    real_import = builtins.__import__
+
+    def reject_bitsandbytes(name, *args, **kwargs):
+        if name == "bitsandbytes":
+            raise ImportError
+        return real_import(name, *args, **kwargs)
+
+    monkeypatch.setattr(builtins, "__import__", reject_bitsandbytes)
+    with pytest.raises(RuntimeError, match="pip install -U bitsandbytes"):
+        loader.load_model("x", quantization="4bit")
+
+
+@pytest.mark.parametrize("quantization", ["4bit", "8bit"])
+def test_cuda_quantization_builds_explicit_config(loader_boundary, monkeypatch, quantization):
+    made = []
+
+    def fake_bnb(**kwargs):
+        made.append(kwargs)
+        return kwargs
+
+    monkeypatch.setattr(loader.dev, "get_device", lambda _preference="auto": "cuda")
+    monkeypatch.setattr(loader.dev, "supports_bitsandbytes", lambda _device=None: True)
+    monkeypatch.setattr("transformers.BitsAndBytesConfig", fake_bnb)
+    handle = loader.load_model("x", quantization=quantization, skip_snapshot=True)
+    kwargs = loader_boundary.model_class.from_pretrained.call_args.kwargs
+    assert kwargs["device_map"] == "auto"
+    assert kwargs["quantization_config"] == made[0]
+    assert made[0][f"load_in_{quantization}"] is True
+    assert made[0]["llm_int8_enable_fp32_cpu_offload"] is True
+    handle.cleanup()
+
+
+def test_native_quantization_wins_and_skips_dtype(loader_boundary):
+    loader_boundary.config.quantization_config = SimpleNamespace()
+    handle = loader.load_model("x", quantization="4bit", skip_snapshot=True)
+    kwargs = loader_boundary.model_class.from_pretrained.call_args.kwargs
+    assert "torch_dtype" not in kwargs
+    assert kwargs["device_map"] == "auto"
+    assert "quantization_config" not in kwargs
+    handle.cleanup()
+
+
+def test_cuda_auto_map_has_bounded_memory_and_requested_offload(loader_boundary, monkeypatch, tmp_path):
+    gib = 1024**3
+    monkeypatch.setattr(loader.dev, "get_device", lambda _preference="auto": "cuda")
+    monkeypatch.setattr(loader.dev, "supports_device_map_auto", lambda _device=None: True)
+    monkeypatch.setattr(loader.dev, "is_cuda", lambda: True)
+    monkeypatch.setattr(loader.dev, "device_count", lambda: 2)
+    monkeypatch.setattr(loader.dev, "_system_memory_gb", lambda: (64.0, 40.0))
+    monkeypatch.setattr(
+        loader.torch.cuda,
+        "get_device_properties",
+        lambda _index: SimpleNamespace(total_memory=20 * gib),
+    )
+    handle = loader.load_model("x", offload_folder=str(tmp_path), skip_snapshot=True)
+    kwargs = loader_boundary.model_class.from_pretrained.call_args.kwargs
+    assert kwargs["offload_folder"] == str(tmp_path)
+    assert kwargs["max_memory"] == {0: "17408MiB", 1: "17408MiB", "cpu": "54GiB"}
+    handle.cleanup()
+    assert tmp_path.exists(), "cleanup must not remove an operator-owned directory"
+
+
+def test_model_permission_error_retries_and_explicit_device_moves(loader_boundary, monkeypatch, tmp_path):
+    monkeypatch.setattr(loader.tempfile, "gettempdir", lambda: str(tmp_path))
+    loader_boundary.model_class.from_pretrained.side_effect = [PermissionError("cache"), loader_boundary.model]
+    loader.load_model("x", device="cpu", skip_snapshot=True)
+    assert loader_boundary.model_class.from_pretrained.call_count == 2
+    assert loader_boundary.model_class.from_pretrained.call_args.kwargs["cache_dir"].endswith("hf_home/hub")
+    loader_boundary.model.to.assert_called_once_with("cpu")
+
+
+def test_model_gated_and_unknown_architecture_errors_are_actionable(loader_boundary):
+    loader_boundary.model_class.from_pretrained.side_effect = OSError("gated repo")
+    with pytest.raises(RuntimeError, match="Accept the license"):
+        loader.load_model("owner/gated")
+
+    loader_boundary.model_class.from_pretrained.side_effect = ValueError("does not recognize this architecture")
+    with pytest.raises(RuntimeError, match="pip install --upgrade transformers"):
+        loader.load_model("new/model")
+
+    loader_boundary.model_class.from_pretrained.side_effect = KeyError("unrelated")
+    with pytest.raises(KeyError, match="unrelated"):
+        loader.load_model("x")
+
+
+def test_tokenizer_permission_retry_and_forced_snapshot(loader_boundary, monkeypatch, tmp_path):
+    monkeypatch.setattr(loader.tempfile, "gettempdir", lambda: str(tmp_path))
+    loader.AutoTokenizer.from_pretrained.side_effect = [PermissionError("cache"), loader_boundary.tokenizer]
+    handle = loader.load_model("x", skip_snapshot=False)
+    assert loader.AutoTokenizer.from_pretrained.call_count == 2
+    assert loader.AutoTokenizer.from_pretrained.call_args.kwargs["cache_dir"].endswith("hf_home/hub")
+    assert handle._original_state is not None
+
+
+@pytest.mark.parametrize(
+    ("native", "initial_free", "remaining_free", "snapshots"),
+    [
+        (True, 10.0, 3.0, 0),
+        (True, 10.0, 6.0, 1),
+        (False, 0.000001, 0.0, 0),
+        (False, 0.0, 0.0, 1),
+    ],
+)
+def test_automatic_snapshot_memory_policy(
+    loader_boundary, monkeypatch, native, initial_free, remaining_free, snapshots,
+):
+    if native:
+        loader_boundary.config.quantization_config = SimpleNamespace()
+    monkeypatch.setattr(loader.dev, "get_total_free_gb", Mock(side_effect=[initial_free, remaining_free]))
+    snapshot = Mock()
+    monkeypatch.setattr(loader.ModelHandle, "snapshot", snapshot)
+    handle = loader.load_model("x")
+    assert snapshot.call_count == snapshots
+    handle.cleanup()
diff --git a/tests/test_mlx_backend_boundaries.py b/tests/test_mlx_backend_boundaries.py
new file mode 100644
index 0000000..6913ba9
--- /dev/null
+++ b/tests/test_mlx_backend_boundaries.py
@@ -0,0 +1,170 @@
+"""Simulated MLX contracts that run without Apple hardware or MLX packages."""
+
+from __future__ import annotations
+
+import sys
+from types import ModuleType, SimpleNamespace
+from unittest.mock import Mock
+
+import numpy as np
+import pytest
+import torch
+
+from obliteratus import mlx_backend
+
+
+@pytest.fixture
+def fake_mlx(monkeypatch):
+    core = ModuleType("mlx.core")
+    core.array = np.array
+    core.eval = Mock()
+    core.matmul = np.matmul
+    core.save_safetensors = Mock()
+    nn = ModuleType("mlx.nn")
+    package = ModuleType("mlx")
+    package.core = core
+    package.nn = nn
+    lm = ModuleType("mlx_lm")
+    lm.load = Mock(return_value=(SimpleNamespace(config={"kind": "fixture"}), SimpleNamespace()))
+    lm.generate = Mock(return_value="generated")
+    lm.upload_to_hub = Mock()
+    monkeypatch.setitem(sys.modules, "mlx", package)
+    monkeypatch.setitem(sys.modules, "mlx.core", core)
+    monkeypatch.setitem(sys.modules, "mlx.nn", nn)
+    monkeypatch.setitem(sys.modules, "mlx_lm", lm)
+    monkeypatch.setattr(mlx_backend, "MLX_AVAILABLE", True)
+    monkeypatch.setattr(mlx_backend, "_mx", core)
+    monkeypatch.setattr(mlx_backend, "_mlx_nn", nn)
+    monkeypatch.setattr(mlx_backend, "_mlx_lm", lm)
+    return SimpleNamespace(core=core, lm=lm)
+
+
+@pytest.mark.parametrize(
+    "call",
+    [
+        lambda: mlx_backend.load_model("model"),
+        lambda: mlx_backend.generate(SimpleNamespace(), "prompt"),
+        lambda: mlx_backend.get_activations(SimpleNamespace(), [], []),
+        lambda: mlx_backend.get_weight(SimpleNamespace(), 0, "weight"),
+        lambda: mlx_backend.modify_weights(SimpleNamespace(), 0, "weight", lambda value: value),
+        lambda: mlx_backend.project_out_direction(None, None),
+        lambda: mlx_backend.save_model(SimpleNamespace(), "out"),
+        lambda: mlx_backend.torch_tensor_to_mlx(torch.ones(1)),
+    ],
+)
+def test_missing_mlx_fails_with_install_guidance(monkeypatch, call):
+    monkeypatch.setattr(mlx_backend, "MLX_AVAILABLE", False)
+    with pytest.raises(RuntimeError, match="pip install mlx>=0.22 mlx-lm>=0.20"):
+        call()
+
+
+def test_load_generate_and_handle_config(fake_mlx):
+    handle = mlx_backend.load_model("local/model", dtype="bfloat16")
+    assert handle.model_name == "local/model"
+    assert handle.config == {"kind": "fixture"}
+    fake_mlx.lm.load.assert_called_once_with("local/model")
+    assert mlx_backend.generate(
+        handle,
+        "prompt",
+        max_tokens=4,
+        temperature=0.2,
+        top_p=0.8,
+        repetition_penalty=1.1,
+    ) == "generated"
+    assert fake_mlx.lm.generate.call_args.kwargs == {
+        "prompt": "prompt",
+        "max_tokens": 4,
+        "temp": 0.2,
+        "top_p": 0.8,
+        "repetition_penalty": 1.1,
+    }
+    mlx_backend.generate(handle, "prompt", repetition_penalty=None)
+    assert "repetition_penalty" not in fake_mlx.lm.generate.call_args.kwargs
+
+
+class _Layer:
+    def __call__(self, value):
+        return (value + 1, "attention")
+
+
+def test_activation_capture_supports_llama_and_truncation(fake_mlx):
+    inner = SimpleNamespace(
+        layers=[_Layer(), _Layer()],
+        embed_tokens=lambda ids: np.repeat(ids[:, :, None], 3, axis=2),
+    )
+    handle = mlx_backend.MLXModelHandle(
+        model=SimpleNamespace(model=inner),
+        tokenizer=SimpleNamespace(encode=lambda _prompt: [1, 2, 3, 4]),
+        model_name="fixture",
+    )
+    activations = mlx_backend.get_activations(handle, ["a", "b"], [0, 1], max_length=2)
+    assert np.array_equal(activations[0][0], np.array([3, 3, 3]))
+    assert np.array_equal(activations[1][1], np.array([4, 4, 4]))
+    assert fake_mlx.core.eval.call_count == 4
+
+
+def test_activation_capture_rejects_unknown_layers_and_embeddings(fake_mlx):
+    handle = mlx_backend.MLXModelHandle(SimpleNamespace(), SimpleNamespace(), "unknown")
+    with pytest.raises(RuntimeError, match="Cannot locate transformer layers"):
+        mlx_backend.get_activations(handle, ["x"], [0])
+
+    model = SimpleNamespace(model=SimpleNamespace(layers=[_Layer()]))
+    handle = mlx_backend.MLXModelHandle(model, SimpleNamespace(encode=lambda _prompt: [1]), "unknown")
+    with pytest.raises(RuntimeError, match="Cannot find embedding layer"):
+        mlx_backend.get_activations(handle, ["x"], [0])
+
+
+def test_get_and_modify_weights_support_update_and_assignment(fake_mlx):
+    update_parent = SimpleNamespace(weight=np.array([1.0]), update=Mock())
+    assign_parent = SimpleNamespace(weight=np.array([2.0]))
+    layers = [SimpleNamespace(attention=update_parent), SimpleNamespace(attention=assign_parent)]
+    handle = mlx_backend.MLXModelHandle(
+        SimpleNamespace(transformer=SimpleNamespace(h=layers)),
+        SimpleNamespace(),
+        "fixture",
+    )
+    assert np.array_equal(mlx_backend.get_weight(handle, 0, "attention.weight"), np.array([1.0]))
+    mlx_backend.modify_weights(handle, 0, "attention.weight", lambda value: value + 1)
+    update_parent.update.assert_called_once()
+    mlx_backend.modify_weights(handle, 1, "attention.weight", lambda value: value + 1)
+    assert np.array_equal(assign_parent.weight, np.array([3.0]))
+    assert fake_mlx.core.eval.call_count == 2
+
+
+def test_projection_removes_requested_direction(fake_mlx):
+    weight = np.array([[2.0, 3.0], [4.0, 5.0]])
+    direction = np.array([1.0, 0.0])
+    projected = mlx_backend.project_out_direction(weight, direction)
+    assert np.array_equal(projected, np.array([[0.0, 3.0], [0.0, 5.0]]))
+
+
+def test_save_model_native_fallback_and_upload(fake_mlx, monkeypatch, tmp_path):
+    tokenizer = SimpleNamespace(save_pretrained=Mock())
+    model = SimpleNamespace(parameters=lambda: {"block": {"weight": np.array([1.0])}}.items())
+    handle = mlx_backend.MLXModelHandle(model, tokenizer, "fixture")
+    fake_mlx.lm.save_model = Mock()
+    out = mlx_backend.save_model(handle, tmp_path / "native", upload_repo="org/model")
+    assert out.is_dir()
+    fake_mlx.lm.save_model.assert_called_once()
+    fake_mlx.lm.upload_to_hub.assert_called_once_with(str(out), "org/model")
+
+    del fake_mlx.lm.save_model
+    out = mlx_backend.save_model(handle, tmp_path / "fallback")
+    fake_mlx.core.save_safetensors.assert_called_once()
+    tokenizer.save_pretrained.assert_called_once_with(str(out))
+
+
+def test_tensor_conversions_and_internal_helpers(fake_mlx):
+    source = torch.tensor([1.0, 2.0], requires_grad=True)
+    converted = mlx_backend.torch_tensor_to_mlx(source)
+    assert np.array_equal(converted, np.array([1.0, 2.0], dtype=np.float32))
+    restored = mlx_backend.mlx_to_torch_tensor(np.array([3.0]), device="cpu")
+    assert torch.equal(restored, torch.tensor([3.0], dtype=torch.float64))
+
+    layers = [object()]
+    assert mlx_backend._get_layers(SimpleNamespace(gpt_neox=SimpleNamespace(layers=layers))) is layers
+    with pytest.raises(RuntimeError, match="Cannot locate transformer layers"):
+        mlx_backend._get_layers(SimpleNamespace())
+    flattened = {}
+    mlx_backend._flatten_dict({"a": {"b": 1}, "c": 2}, "", flattened)
+    assert flattened == {"a.b": 1, "c": 2}