[AZ-358] [AZ-361] C4 OpenCVGtsamPoseEstimator + Jacobian thermal hybrid

Implement the single production-default C4 PoseEstimator strategy.

AZ-358 — Marginals path: OpenCV solvePnPRansac (SOLVEPNP_IPPE) on
best-candidate inliers, PriorFactorPose3 with Jacobian-derived initial
covariance, flushed into C5's iSAM2 graph via the widened
ISam2GraphHandle.update(graph, values, None) (Option B). Posterior
covariance from compute_marginals().marginalCovariance(pose_key) with
SPD-defensive Cholesky check. Tile pixel -> ENU world conversion via
the shared WgsConverter + a configurable tile_size_px. Two spec
deviations now documented in the AZ-358 task file: PriorFactorPose3
over GenericProjectionFactorCal3DS2 (avoids unbounded landmark
variables; same Fisher information on the pose marginal) and explicit
(graph, values, timestamps) update args (aligns with C5's impl).

AZ-361 — Jacobian + thermal hybrid: per-frame dispatch on
thermal_state.thermal_throttle_active selects the cv2.projectPoints-
derived 6x6 information matrix (with ridge regularisation) as the
emitted covariance. Skips the iSAM2 factor add under throttle
(Invariant 12). Emits CovarianceDegradedWarning via warnings.warn
(never raised); paired WARN log + FDR record rate-limited per
covariance_degraded_warn_window_ns (default 60 s) via an injected
monotonic Clock. Supersedes the AZ-358 NotImplementedError stub.

Widens ISam2GraphHandle from get_pose_key only to all five C4-facing
methods (add_factor, update, compute_marginals, last_anchor_age_ms);
C5's existing ISam2GraphHandleImpl already satisfies the superset, so
no C5 source change this batch. Threads fdr_client + clock through
pose_factory composition.

Registers two new FDR payload kinds: pose.frame_done (per-call
telemetry; both success and PnpFailureError paths) and
pose.covariance_degraded (per-window throttle exposure).

Tests: 21 new (AZ-358 AC-1..11 + AZ-361 AC-1..10/12/13; AZ-361 AC-11
RMSE-ratio informational per spec, not asserted). Updates 2 existing
test files for Protocol widening and the FDR-schema round trip.

Code review verdict: PASS_WITH_WARNINGS (5 findings: Medium x2,
Low x3; none blocking). Full suite: 1958 passed, 1 unrelated
host-dependent perf failure (c12 CLI cold-start, pre-existing).

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/unit/c4_pose/test_az355_pose_protocol.py

@@ -78,11 +78,28 @@ def _build_config(**overrides: Any) -> Config:
 
 
 class _FakeISam2GraphHandle:
-    """Minimal handle stub for factory / Protocol tests."""
+    """Minimal handle stub for factory / Protocol tests.
+
+    Implements the AZ-358-extended 5-method surface — the AZ-355
+    AC-10 ``isinstance(handle, ISam2GraphHandle)`` runtime-checkable
+    test now expects all five methods.
+    """
 
     def get_pose_key(self, frame_id: int) -> int:
         return int(frame_id)
 
+    def add_factor(self, factor: Any) -> None:
+        return None
+
+    def update(self, graph: Any, values: Any, timestamps: Any | None = None) -> None:
+        return None
+
+    def compute_marginals(self) -> Any:
+        return None
+
+    def last_anchor_age_ms(self) -> int:
+        return 0
+
 
 class _FakePoseEstimator:
     """Test double satisfying the full PoseEstimator Protocol."""
@@ -378,6 +395,18 @@ def test_ac10_isam2_graph_handle_rejects_missing_method() -> None:
     assert not isinstance(_NoMethod(), ISam2GraphHandle)
 
 
+def test_ac10_isam2_graph_handle_rejects_partial_surface() -> None:
+    """AZ-358 widened the Protocol to 5 methods; a handle that only
+    implements the original ``get_pose_key`` no longer satisfies
+    runtime_checkable conformance."""
+
+    class _OnlyGetPoseKey:
+        def get_pose_key(self, frame_id: int) -> int:
+            return int(frame_id)
+
+    assert not isinstance(_OnlyGetPoseKey(), ISam2GraphHandle)
+
+
 # ---------------------------------------------------------------------
 # Bonus: factory wires constructor dependencies through to the strategy
 
@@ -411,19 +440,23 @@ def test_factory_passes_dependencies_to_strategy() -> None:
 
 
 def test_factory_lazy_imports_when_registry_empty() -> None:
+    # Arrange — registry is empty (fixture cleared it); the
+    # lazy-import fallback should pick up the AZ-358 concrete
+    # ``opencv_gtsam_estimator`` module and resolve its ``create``
+    # callable.
     cfg = _build_config()
-    # Registry is cleared by the fixture; the lazy-import fallback
-    # should attempt to import the concrete module. We have not
-    # shipped opencv_gtsam_estimator yet (AZ-358), so the import
-    # raises and gets wrapped in PoseEstimatorConfigError.
-    with pytest.raises(PoseEstimatorConfigError):
-        build_pose_estimator(
-            cfg,
-            ransac_filter=mock.MagicMock(),
-            wgs_converter=mock.MagicMock(),
-            se3_utils=mock.MagicMock(),
-            isam2_graph_handle=_FakeISam2GraphHandle(),
-        )
+
+    # Act — call should succeed (lazy import resolves to AZ-358).
+    estimator = build_pose_estimator(
+        cfg,
+        ransac_filter=mock.MagicMock(),
+        wgs_converter=mock.MagicMock(),
+        se3_utils=mock.MagicMock(),
+        isam2_graph_handle=_FakeISam2GraphHandle(),
+    )
+
+    # Assert — the returned object satisfies the PoseEstimator Protocol.
+    assert isinstance(estimator, PoseEstimator)
 
 
 # ---------------------------------------------------------------------