feat(stage2-phase2): structlog hot-path, pytest markers, obs package

Phase 2 deliverables not yet committed from plan execution:
- structlog wired to 10 hot-path files (orchestrator, eskf, components)
- bind_contextvars(correlation_id=frame_id) in process_frame
- obs/logging_config.py: configure_logging(env) JSON/console renderer
- pyproject.toml: structlog>=25.1, --strict-markers, 6 markers registered
- tests/conftest.py: ac(id) validator plugin + pytest_collection hooks

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/conftest.py

@@ -9,6 +9,96 @@ from gps_denied.core.coordinates import CoordinateTransformer
 from gps_denied.core.models import ModelManager
 from gps_denied.schemas import CameraParameters, GPSPoint
 
+# ---------------------------------------------------------------
+# Phase 2 / TEST-03: AC traceability plugin
+#
+# Registers categorical markers (defensive — pyproject.toml is primary), validates
+# @pytest.mark.ac() arguments against the canonical AC-ID regex at collection time,
+# and (when --ac-dump=<path> is supplied) writes a {ac_id: [test_nodeid, ...]} JSON
+# at session end for `scripts/gen_ac_traceability.py` to consume.
+#
+# See RESEARCH.md §2.1 for the canonical implementation and rationale.
+# ---------------------------------------------------------------
+import json
+import re
+from collections import defaultdict
+from pathlib import Path
+
+_AC_ID_RE = re.compile(r"^AC-(?:\d+\.\d+[a-z]?|NEW-\d+)$")
+
+
+def pytest_configure(config):
+    """Defensive marker registration. Primary registration lives in pyproject.toml,
+    but doing it here too means a future maintainer who drops the pyproject markers
+    list does not silently break --strict-markers."""
+    for line in (
+        "unit: pure-math or single-class test; no I/O",
+        "integration: cross-subsystem test; in-memory SQLite / ASGI / full wiring",
+        "blackbox: validates external contract without a live producer",
+        "sitl: requires ARDUPILOT_SITL_HOST — nightly only",
+        "e2e: full-pipeline run against a real dataset — nightly only",
+        "ac(ac_id): link test to one or more Acceptance Criteria (e.g. AC-1.1, AC-NEW-3)",
+    ):
+        config.addinivalue_line("markers", line)
+
+
+def pytest_addoption(parser):
+    parser.addoption(
+        "--ac-dump",
+        action="store",
+        default=None,
+        help="Path to write the {ac_id: [test_nodeid, ...]} JSON at session end. "
+             "Consumed by scripts/gen_ac_traceability.py.",
+    )
+
+
+def pytest_collection_modifyitems(config, items):
+    """Validate @pytest.mark.ac(...) arguments against the canonical AC-ID regex.
+
+    Fail collection (rather than emit a runtime error) so AC-ID typos surface immediately.
+    The traceability script's --check mode catches forward orphans (AC without test);
+    this hook catches backward orphans (test references non-existent AC) by enforcing
+    the syntactic AC-ID shape. Semantic existence (AC ID is declared in the AC doc) is
+    enforced by the script in Plan 02-04.
+    """
+    errors = []
+    for item in items:
+        for mark in item.iter_markers(name="ac"):
+            if not mark.args:
+                errors.append(
+                    f"{item.nodeid}: @pytest.mark.ac() requires at least one AC ID arg"
+                )
+                continue
+            for arg in mark.args:
+                if not isinstance(arg, str) or not _AC_ID_RE.match(arg):
+                    errors.append(
+                        f"{item.nodeid}: @pytest.mark.ac({arg!r}) — must match "
+                        f"AC-X.Y or AC-NEW-N (e.g. 'AC-1.1', 'AC-NEW-3')"
+                    )
+    if errors:
+        raise pytest.UsageError(
+            "AC marker validation failed:\n  " + "\n  ".join(errors)
+        )
+
+
+def pytest_sessionfinish(session, exitstatus):
+    """Dump {ac_id: [test_nodeid, ...]} to --ac-dump path if supplied.
+
+    Runs even when pytest is invoked with --collect-only (session.items is populated
+    before tests execute), so scripts/gen_ac_traceability.py can dump in ~seconds on a
+    full suite.
+    """
+    dump_path = session.config.getoption("--ac-dump", default=None)
+    if not dump_path:
+        return
+    mapping: dict[str, list[str]] = defaultdict(list)
+    for item in session.items:
+        for mark in item.iter_markers(name="ac"):
+            for ac_id in mark.args:
+                mapping[ac_id].append(item.nodeid)
+    Path(dump_path).write_text(json.dumps(dict(sorted(mapping.items())), indent=2))
+
+
 # ---------------------------------------------------------------
 # Common constants
 # ---------------------------------------------------------------