feat(v0.18.0): W7 — OOM / prefill layer

Phase 3 wave W7 of the metal-guard public reconciliation. New submodules
oom_precheck / prefill_exposure_tracker / worker_rotation. prefill_guard
confirmed already-public (no port). R1+R2 critic GO. Suite 517 -> 555.

Author: Harper

CHANGELOG.md

@@ -5,6 +5,35 @@ All notable changes to **metal-guard** are documented here.
 The format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/)
 and this project adheres to [Semantic Versioning](https://semver.org/).
 
+## [0.18.0] — 2026-05-18
+
+**Drift-audit wave W7** — OOM / prefill layer.
+
+### Added
+
+- **`metal_guard.oom_precheck`** — high-level pre-call OOM gate wrapping
+  the prefill-allocation math with model-dims / GPU-memory auto-fetch
+  (`precheck_inference`, `precheck_inference_or_raise`, `OOMVerdict`).
+- **`metal_guard.prefill_exposure_tracker`** — per-worker cumulative
+  prefill-tokens lifetime tracker for the delayed-trigger panic class
+  (`record_prefill`, `get_state`, `forget_worker`, `all_states`,
+  `WorkerPrefillState`).
+- **`metal_guard.worker_rotation`** — advisory prefill-budget worker
+  rotation gate (`should_rotate_worker`, `RotationVerdict`,
+  `REASON_DISABLED` / `REASON_NO_STATE` / `REASON_UNDER_BUDGET` /
+  `REASON_PREFILL_BUDGET_EXCEEDED`).
+
+### Changed
+
+- Public API surface grows by 14 names; `tests/test_phase1_facade.py`
+  surface lock updated 151 -> 165.
+
+### Notes
+
+- `prefill_guard` needed no port — its full surface already lives in
+  `metal_guard.prefill` since the Phase 1 refactor (regression-locked by
+  `tests/test_w7_already_public.py`).
+
 ## [0.17.0] — 2026-05-18
 
 **Drift-audit wave W6** — Wave-A safety nets.

metal_guard/__init__.py

@@ -222,6 +222,26 @@
     poll_for_early_death,
 )
 from metal_guard.safe_shutdown import ShutdownReport, safe_inference_shutdown
+from metal_guard.oom_precheck import (
+    OOMVerdict,
+    precheck_inference,
+    precheck_inference_or_raise,
+)
+from metal_guard.prefill_exposure_tracker import (
+    WorkerPrefillState,
+    all_states,
+    forget_worker,
+    get_state,
+    record_prefill,
+)
+from metal_guard.worker_rotation import (
+    REASON_DISABLED,
+    REASON_NO_STATE,
+    REASON_PREFILL_BUDGET_EXCEEDED,
+    REASON_UNDER_BUDGET,
+    RotationVerdict,
+    should_rotate_worker,
+)
 
 # ---------------------------------------------------------------------------
 # Private re-exports — underscore-prefixed names that existing tests / callers
@@ -454,4 +474,21 @@
     # safe_shutdown (W6)
     "safe_inference_shutdown",
     "ShutdownReport",
+    # oom_precheck (W7)
+    "OOMVerdict",
+    "precheck_inference",
+    "precheck_inference_or_raise",
+    # prefill_exposure_tracker (W7)
+    "WorkerPrefillState",
+    "record_prefill",
+    "get_state",
+    "forget_worker",
+    "all_states",
+    # worker_rotation (W7)
+    "should_rotate_worker",
+    "RotationVerdict",
+    "REASON_DISABLED",
+    "REASON_NO_STATE",
+    "REASON_UNDER_BUDGET",
+    "REASON_PREFILL_BUDGET_EXCEEDED",
 ]

metal_guard/_constants.py

@@ -10,7 +10,7 @@
 import os
 from typing import TypeVar
 
-__version__ = "0.17.0"
+__version__ = "0.18.0"
 
 log = logging.getLogger("metal_guard")