diff --git a/strix/llm/warmup.py b/strix/llm/warmup.py
index 98da959d..0459469d 100644
--- a/strix/llm/warmup.py
+++ b/strix/llm/warmup.py
@@ -14,6 +14,7 @@ from __future__ import annotations
 
 import importlib
 import logging
+import sys
 import threading
 
 
@@ -30,12 +31,38 @@ _lock = threading.Lock()
 _thread: threading.Thread | None = None
 
 
+def _purge_orphaned_modules(before: frozenset[str]) -> None:
+    """Remove submodules stranded by an import attempt that just failed.
+
+    When a package import fails partway (for example CPython's import-lock
+    deadlock avoidance breaking a cross-thread cycle), the failed package is
+    removed from ``sys.modules`` but submodules it already finished stay
+    behind. A later import of one of those submodules then short-circuits on
+    the cached entry without re-importing its parent, and re-entering the
+    parent from inside a submodule crashes with "partially initialized
+    module". Dropping the orphans (cached submodules whose ancestor package is
+    gone) restores a clean slate, and touches nothing another thread imported
+    successfully.
+    """
+    added = set(sys.modules) - before
+    for name in added:
+        parent = name.rpartition(".")[0]
+        while parent:
+            if parent not in sys.modules:
+                sys.modules.pop(name, None)
+                logger.debug("Import warm-up purged orphaned module %r", name)
+                break
+            parent = parent.rpartition(".")[0]
+
+
 def _warm(modules: tuple[str, ...]) -> None:
     for name in modules:
+        before = frozenset(sys.modules)
         try:
             importlib.import_module(name)
         except Exception:  # noqa: BLE001 - a failed warm-up must never fail the run.
             logger.debug("Import warm-up for %r failed", name, exc_info=True)
+            _purge_orphaned_modules(before)
 
 
 def start_import_warmup(modules: tuple[str, ...] = WARMUP_MODULES) -> threading.Thread:
diff --git a/strix/report/__init__.py b/strix/report/__init__.py
index c8c80eec..dca4114b 100644
--- a/strix/report/__init__.py
+++ b/strix/report/__init__.py
@@ -1,12 +1,26 @@
 """Report/finding helpers."""
 
-from strix.report.dedupe import check_duplicate
+from importlib import import_module
+from typing import TYPE_CHECKING, Any
+
 from strix.report.state import ReportState, get_global_report_state, set_global_report_state
 
 
+if TYPE_CHECKING:
+    from strix.report.dedupe import check_duplicate
+
 __all__ = [
     "ReportState",
     "check_duplicate",
     "get_global_report_state",
     "set_global_report_state",
 ]
+
+
+def __getattr__(name: str) -> Any:
+    # check_duplicate pulls in the agents SDK import graph, so it resolves
+    # lazily: importing this package must stay lightweight and never enter
+    # that graph (the import warm-up thread may be walking it concurrently).
+    if name == "check_duplicate":
+        return import_module("strix.report.dedupe").check_duplicate
+    raise AttributeError(name)
diff --git a/strix/report/state.py b/strix/report/state.py
index 623cb9e9..a665adea 100644
--- a/strix/report/state.py
+++ b/strix/report/state.py
@@ -6,18 +6,15 @@ from collections.abc import Callable
 from datetime import UTC, datetime
 from importlib.metadata import PackageNotFoundError, version
 from pathlib import Path
-from typing import Any, Optional, cast
+from typing import TYPE_CHECKING, Any, Optional, cast
 from uuid import uuid4
 
-from agents.usage import Usage
-
 from strix.config import codex
 from strix.config.loader import load_settings
 from strix.core.paths import run_dir_for, runtime_state_dir
 from strix.report.coverage import write_coverage
 from strix.report.pricing import resolve_litellm_model
 from strix.report.sarif import write_sarif
-from strix.report.usage import LLMUsageLedger
 from strix.report.writer import (
     read_run_record,
     write_executive_report,
@@ -27,6 +24,10 @@ from strix.report.writer import (
 from strix.telemetry import posthog, scarf
 
 
+if TYPE_CHECKING:
+    from agents.usage import Usage
+
+
 logger = logging.getLogger(__name__)
 
 _global_report_state: Optional["ReportState"] = None
@@ -131,6 +132,10 @@ class ReportState:
 
         self.scan_results: dict[str, Any] | None = None
         self.scan_config: dict[str, Any] | None = None
+        # Imported here so importing this module never enters the agents SDK
+        # package (which the warm-up thread may be initializing concurrently).
+        from strix.report.usage import LLMUsageLedger
+
         self._llm_usage = LLMUsageLedger()
         self._telemetry_llm_usage_baseline: dict[str, Any] = {}
         auth_mode = codex.auth_mode(load_settings().llm.model)
@@ -338,7 +343,7 @@ class ReportState:
         self,
         *,
         agent_id: str,
-        usage: Usage | None,
+        usage: "Usage | None",
         agent_name: str | None = None,
         model: str | None = None,
     ) -> None:
diff --git a/tests/test_import_warmup.py b/tests/test_import_warmup.py
new file mode 100644
index 00000000..64d3bfba
--- /dev/null
+++ b/tests/test_import_warmup.py
@@ -0,0 +1,99 @@
+"""The import warm-up thread must never leave the import system poisoned.
+
+Field failure: the warm-up thread's ``strix.core.runner`` import and the main
+thread's ``strix.report`` import both walked the agents SDK graph, and the two
+held each other's import locks (report -> dedupe -> agents while runner ->
+hooks -> report.state). CPython's deadlock avoidance breaks such a cycle by
+failing one import, which strands finished submodules in ``sys.modules`` with
+their parent package gone — and the next import of one of those submodules
+crashes with "partially initialized module".
+"""
+
+from __future__ import annotations
+
+import subprocess
+import sys
+import textwrap
+
+from strix.llm import warmup
+
+
+def _run(code: str) -> subprocess.CompletedProcess[str]:
+    return subprocess.run(  # noqa: S603
+        [sys.executable, "-c", textwrap.dedent(code)],
+        capture_output=True,
+        text=True,
+        check=False,
+        timeout=300,
+    )
+
+
+def test_strix_report_does_not_import_the_agents_graph() -> None:
+    result = _run(
+        """
+        import sys
+
+        import strix.report
+
+        agents_modules = [m for m in sys.modules if m == "agents" or m.startswith("agents.")]
+        assert not agents_modules, agents_modules
+        assert "strix.report.dedupe" not in sys.modules
+        """
+    )
+    assert result.returncode == 0, result.stderr
+
+
+def test_check_duplicate_resolves_lazily() -> None:
+    result = _run(
+        """
+        import strix.report
+        from strix.report import check_duplicate
+        from strix.report.dedupe import check_duplicate as direct
+
+        assert strix.report.check_duplicate is direct is check_duplicate
+        """
+    )
+    assert result.returncode == 0, result.stderr
+
+
+def test_failed_warm_import_purges_orphaned_submodules() -> None:
+    result = _run(
+        """
+        import sys
+
+        from strix.llm.warmup import _warm
+
+        # A package whose import fails after a submodule already completed:
+        # CPython removes the package but leaves the submodule stranded.
+        import pathlib
+        import tempfile
+
+        root = pathlib.Path(tempfile.mkdtemp())
+        pkg = root / "stranded_pkg"
+        pkg.mkdir()
+        (pkg / "ok.py").write_text("VALUE = 1")
+        (pkg / "__init__.py").write_text("from . import ok\\nraise RuntimeError('boom')")
+        sys.path.insert(0, str(root))
+
+        _warm(("stranded_pkg",))
+
+        assert "stranded_pkg" not in sys.modules
+        assert "stranded_pkg.ok" not in sys.modules, "orphan survived the purge"
+
+        # And the subtree imports cleanly afterwards up to the real error.
+        try:
+            import stranded_pkg  # noqa: F401
+        except RuntimeError:
+            pass
+        else:
+            raise AssertionError("expected the package's own error")
+        """
+    )
+    assert result.returncode == 0, result.stderr
+
+
+def test_purge_does_not_touch_preexisting_or_healthy_modules() -> None:
+    before = frozenset(sys.modules) - {"strix.llm.warmup"}
+    warmup._purge_orphaned_modules(before)
+    assert "strix.llm.warmup" in sys.modules  # parent chain intact -> kept
+    assert "strix" in sys.modules