[AZ-266] [AZ-269] [AZ-277] [AZ-280] Cross-cutting log/config + SE3/SHA256 helpers

AZ-266: schema-compliant JSON logging entrypoint, level normalisation,
handler-topology guard, format-error fallback (log_record_schema v1.0.0).
AZ-269: env > YAML > defaults config loader, frozen Config dataclass,
missing-var fail-fast with pointer to .env.example, component-block registry.
AZ-277: GTSAM-backed SE3Utils (matrix<->SE3 + exp/log/adjoint) with strict
orthogonality, dtype, and bottom-row contract enforcement.
AZ-280: atomicwrites-backed write_atomic + independent verify +
order-deterministic aggregate_hash; sidecar format strictness.
pyproject.toml pins gtsam>=4.2,<5.0 and atomicwrites>=1.4,<2.0
(named-backend deps per the AZ-277 / AZ-280 contracts).
139 unit tests pass (44 new). Review verdict: PASS_WITH_WARNINGS;
findings are perf-NFR + journald deferrals, no blocking issues.

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

_docs/03_implementation/batch_02_cycle1_report.md

@@ -0,0 +1,109 @@
+# Batch Report — Cycle 1 · Batch 2
+
+**Tasks shipped**: AZ-266, AZ-269, AZ-277, AZ-280
+**Date**: 2026-05-11
+**Branch**: dev
+**Review verdict**: PASS_WITH_WARNINGS — see `reviews/batch_02_review.md`
+
+## Tasks
+
+| ID | Title | Owner Layer | Outcome |
+|----|-------|-------------|---------|
+| AZ-266 | Shared Logging Module | cross-cutting / `logging/` | Implemented — schema-compliant JSON formatter, level normalisation, handler topology guard, format-error fallback |
+| AZ-269 | Config Loader | cross-cutting / `config/` | Implemented — env > YAML > defaults precedence, frozen `Config`, missing-var fail-fast with pointer, component-block registry |
+| AZ-277 | SE3Utils Helper | Layer 1 / `helpers/se3_utils.py` | Implemented — GTSAM-backed `matrix_to_se3` / `se3_to_matrix` / `exp_map` / `log_map` / `adjoint` with strict orthogonality + dtype contract |
+| AZ-280 | Sha256Sidecar Helper | Layer 1 / `helpers/sha256_sidecar.py` | Implemented — `atomicwrites`-backed `write_atomic` + independent `verify` + order-deterministic `aggregate_hash` |
+
+## Files Changed
+
+```
+Modified:
+  pyproject.toml                                   (+4 lines : gtsam, atomicwrites pins)
+  src/gps_denied_onboard/config/__init__.py        (re-exports)
+  src/gps_denied_onboard/config/loader.py          (load_config impl)
+  src/gps_denied_onboard/config/schema.py          (frozen dataclasses + component registry)
+  src/gps_denied_onboard/helpers/__init__.py       (re-exports)
+  src/gps_denied_onboard/helpers/se3_utils.py      (SE3 primitives)
+  src/gps_denied_onboard/helpers/sha256_sidecar.py (atomic write + sidecar verify)
+  src/gps_denied_onboard/logging/__init__.py       (re-exports)
+  src/gps_denied_onboard/logging/structured.py     (schema-compliant formatter)
+  tests/unit/test_logging_smoke.py                 (updated to nested kv schema)
+
+Added:
+  tests/unit/test_az266_logging_schema.py
+  tests/unit/test_az269_config_loader.py
+  tests/unit/test_az277_se3_utils.py
+  tests/unit/test_az280_sha256_sidecar.py
+  _docs/03_implementation/reviews/batch_02_review.md
+```
+
+## Test Results
+
+```
+$ pytest tests/unit -q --timeout=30
+139 passed, 2 skipped in 5.27s
+```
+
+Skips are environment-gated (cmake configure step, actionlint), both
+verified in CI.
+
+### AC Coverage
+
+| Task | ACs declared | ACs covered locally | Tier-2 deferred |
+|------|--------------|---------------------|-----------------|
+| AZ-266 | 5 + 2 NFR | 5 ACs + NFR-reliability | NFR-perf (p99 ≤ 0.2 ms on Jetson) |
+| AZ-269 | 6 + 2 NFR | 6 ACs + NFR-reliability | NFR-perf (cold load ≤ 250 ms on Jetson) |
+| AZ-277 | 9 + 2 NFR | 9 ACs + NFR-* via determinism + AST scan | none |
+| AZ-280 | 9 + 2 NFR | 9 ACs + NFR-perf-spot-check + NFR-reliability | none |
+
+Tier-2 perf budgets need hardware to verify against; the unit suite
+does not synthesise a Jetson budget locally. AZ-428..AZ-431 own the
+Tier-2 perf scenarios; the batch-2 modules are wired so those tasks
+plug in without further code changes here.
+
+## Dependency Pins
+
+This batch amended `pyproject.toml` with two new runtime pins required
+by AZ-277 and AZ-280 contracts:
+
+- `gtsam>=4.2,<5.0` — SE(3) backend per AZ-277 contract
+- `atomicwrites>=1.4,<2.0` — atomic-replace backend per AZ-280 contract
+
+Both names appear verbatim in the upstream contract documents and were
+the named-backend constraint, not an arbitrary choice. AZ-263
+intentionally left these unpinned; the pins are added by the first
+batch that needs them.
+
+## Architecture Compliance
+
+- `helpers/se3_utils.py` and `helpers/sha256_sidecar.py` import only
+  stdlib + named externals (numpy / gtsam / atomicwrites). No
+  `gps_denied_onboard.components.*` imports — enforced by AST scan in
+  both helper test files.
+- `logging/structured.py` imports stdlib only (optional `systemd-python`
+  inside the Tier-2 handler factory, lazy).
+- `config/loader.py` imports stdlib + `pyyaml`. The `register_component_block`
+  function is the only authorised path for a component to contribute a
+  config block, satisfying AZ-269 § Risks Mitigation Risk 1.
+
+No new circular imports. Verified by running the test suite (any cycle
+would fail collection).
+
+## Review Findings Summary
+
+Verdict: **PASS_WITH_WARNINGS**. Four Low-severity findings:
+
+1. AC-2 test pivots on `fdr.queue_size` rather than `log.level` — clean
+   test design choice given `LOG_LEVEL` is required-env.
+2. NFR-perf microbenchmarks deferred to Tier-2 perf suite.
+3. Tier-2 journald handler unverified on macOS dev; runs in Jetson CI.
+4. `pyproject.toml` dep amendment — by the consumer batch as designed.
+
+Full details in `reviews/batch_02_review.md`.
+
+## Tracker Transitions
+
+- AZ-266: To Do → In Progress → (batch close) In Testing
+- AZ-269: To Do → In Progress → (batch close) In Testing
+- AZ-277: To Do → In Progress → (batch close) In Testing
+- AZ-280: To Do → In Progress → (batch close) In Testing

_docs/03_implementation/reviews/batch_02_review.md

@@ -0,0 +1,271 @@
+# Code Review Report
+
+**Batch**: 2
+**Tasks**: AZ-266 (Shared Logging Module), AZ-269 (Config Loader), AZ-277 (SE3Utils Helper), AZ-280 (Sha256Sidecar Helper)
+**Date**: 2026-05-11
+**Verdict**: PASS_WITH_WARNINGS
+
+## Scope
+
+Batch 2 lays the cross-cutting foundation: structured JSON logging that
+satisfies the `log_record_schema` v1.0.0 contract, the precedence-aware
+config loader that materialises the frozen `Config` container, and two
+Layer-1 helpers (SE3 math, atomic-write + SHA-256 sidecar) that
+dozens of downstream component tasks depend on.
+
+## Phase 1: Context Loading
+
+Read:
+
+- `_docs/02_tasks/todo/AZ-266_log_module.md` (5 ACs + 2 NFRs)
+- `_docs/02_tasks/todo/AZ-269_config_loader.md` (6 ACs + 2 NFRs)
+- `_docs/02_tasks/todo/AZ-277_se3_utils.md` (9 ACs + 2 NFRs)
+- `_docs/02_tasks/todo/AZ-280_sha256_sidecar.md` (9 ACs + 2 NFRs)
+- Four contracts under `_docs/02_document/contracts/` (log_record_schema,
+  composition_root_protocol, se3_utils, sha256_sidecar)
+- `_docs/02_document/module-layout.md` (ownership envelopes)
+
+Ownership envelopes resolved per `module-layout.md`:
+
+- AZ-266 owns `src/gps_denied_onboard/logging/**` + `tests/unit/test_logging_*.py` + new `test_az266_logging_schema.py`
+- AZ-269 owns `src/gps_denied_onboard/config/**` + `tests/unit/test_az269_config_loader.py`
+- AZ-277 owns `src/gps_denied_onboard/helpers/se3_utils.py` + `tests/unit/test_az277_se3_utils.py`
+- AZ-280 owns `src/gps_denied_onboard/helpers/sha256_sidecar.py` + `tests/unit/test_az280_sha256_sidecar.py`
+
+`pyproject.toml` was amended additively in this batch to pin the
+named-backend dependencies (`gtsam>=4.2,<5.0` and `atomicwrites>=1.4,<2.0`)
+that the AZ-277 / AZ-280 contracts explicitly call out. AZ-263 left
+these unpinned — this batch closes the gap.
+
+## Phase 2: Spec Compliance
+
+### AZ-266 — Shared Logging Module
+
+| AC | Verification |
+|----|--------------|
+| AC-1 Single entrypoint | `test_ac1_get_logger_returns_logger_with_schema_formatter` |
+| AC-2 Field order | `test_ac2_field_order_stable_regardless_of_construction_order` parses raw JSON and asserts tuple-equal order against `CONTRACT_ORDER` |
+| AC-3 Level normalisation | `test_ac3_level_warning_normalises_to_warn` + parametrised pass-through for DEBUG/INFO/ERROR |
+| AC-4 Handler topology | `test_ac4_handler_topology_no_duplicates_on_reinit` (Tier-1; Tier-2 journald handler factory exists but is a runtime-prerequisite skip on macOS dev) |
+| AC-5 Non-frame records | `test_ac5_non_frame_records_emit_explicit_null_frame_id` |
+| NFR-reliability | `test_nfr_formatter_never_raises_on_unserialisable_kv` + `test_nfr_multi_line_msg_is_collapsed` |
+
+NFR-performance (p99 ≤ 0.2 ms on Tier-2) is a Tier-2 microbenchmark; it
+runs under `tests/perf/` (separate file, gated by `pytest.mark.tier2`).
+A formatter cold-bench microbenchmark in unit scope would need a
+hardware-specific budget; the unit suite explicitly leaves this to
+Tier-2. Recorded as a known follow-up below.
+
+### AZ-269 — Config Loader
+
+| AC | Verification |
+|----|--------------|
+| AC-1 env > YAML | `test_ac1_env_beats_yaml` |
+| AC-2 YAML > defaults | `test_ac2_yaml_beats_default_when_env_silent` |
+| AC-3 defaults fill gaps | `test_ac3_defaults_fill_gaps` |
+| AC-4 multi-YAML order | `test_ac4_later_yaml_path_wins` |
+| AC-5 frozen end-to-end | `test_ac5_config_is_frozen_end_to_end` |
+| AC-6 missing-var fail-fast | `test_ac6_missing_required_env_var_fails_with_pointer` |
+| NFR-reliability | `test_nfr_reliability_loader_is_pure` |
+
+NFR-performance (≤ 250 ms cold load on Tier-2) is a hardware-specific
+budget recorded as a Tier-2 follow-up.
+
+### AZ-277 — SE3Utils Helper
+
+| AC | Verification |
+|----|--------------|
+| AC-1 matrix/SE3 round-trip | `test_ac1_matrix_se3_roundtrip_within_tolerance` (20 random Ts) |
+| AC-2 Lie round-trip | `test_ac2_lie_algebra_roundtrip` (20 random ξ) |
+| AC-3 near-identity stability | `test_ac3_near_identity_exp_map_is_stable` |
+| AC-4 strict orthogonality | `test_ac4_strict_orthogonality_rejection` |
+| AC-5 mirror rejected | `test_ac5_mirror_rotation_rejected` |
+| AC-6 bottom-row guard | `test_ac6_bottom_row_guard` |
+| AC-7 dtype contract | `test_ac7_float32_dtype_rejected` |
+| AC-8 determinism | `test_ac8_determinism_byte_equal_outputs` |
+| AC-9 no upward imports | `test_ac9_no_upward_imports_to_components` (AST scan) |
+
+The implementation backs every primitive against GTSAM `Pose3` directly,
+re-exports `SE3 = gtsam.Pose3` per contract, and uses the small-angle
+Taylor cutoff (`|xi| < 1e-10`) for AC-3.
+
+### AZ-280 — Sha256Sidecar Helper
+
+| AC | Verification |
+|----|--------------|
+| AC-1 round-trip | `test_ac1_roundtrip_write_and_verify` (1 MiB seeded payload) |
+| AC-2 atomicity | `test_ac2_atomicity_no_partial_file_on_fault` (monkeypatches `atomicwrites.replace_atomic`) |
+| AC-3 independent verify | `test_ac3_independent_verification_rejects_swapped_payload` |
+| AC-4 missing sidecar raises | `test_ac4_missing_sidecar_raises` |
+| AC-5 malformed sidecar rejected | `test_ac5_malformed_sidecar_rejected` |
+| AC-6 aggregate determinism | `test_ac6_aggregate_hash_order_deterministic` |
+| AC-7 aggregate missing-path | `test_ac7_aggregate_hash_missing_path_raises` |
+| AC-8 sidecar format strict | `test_ac8_sidecar_format_strictness` (64 hex chars, no JSON, no newline, no whitespace) |
+| AC-9 no upward imports | `test_ac9_no_upward_imports_to_components` (AST scan) |
+
+The implementation backs `write_atomic` with `atomicwrites.atomic_write`;
+the sidecar is written via the same atomic primitive; `verify` streams
+the file from disk (no in-memory shortcut) and rejects a missing /
+malformed sidecar with `Sha256SidecarError`.
+
+No Spec-Gap findings.
+
+## Phase 3: Code Quality
+
+- **SRP** — each module owns exactly one concern (the formatter does not
+  also own handler topology; the loader does not own composition; the
+  helpers are pure functions / static methods with no module state).
+- **Error handling** — all four modules use a typed exception
+  (`RequiredFieldMissingError`, `Se3InvalidMatrixError`,
+  `Sha256SidecarError`) wrapping the underlying `OSError` / `ValueError`,
+  so callers handle one hierarchy. The logging formatter never raises
+  into the caller; un-serialisable `kv` is replaced with an
+  `{"_format_error": "..."}` payload.
+- **Naming** — public symbols match the contract files verbatim.
+- **Complexity** — no function exceeds 40 lines; cyclomatic complexity
+  is at most ~5 (the formatter's record-shaping loop).
+- **DRY** — shared sidecar-path computation, contract-field tuple, and
+  reserved-stdlib-keys frozenset all live in module-level constants.
+- **Test quality** — every AC has a directly-mapped test that asserts
+  the contractually-named behaviour; no test bottoms out on "no
+  exception raised". AST-based `no upward imports` scans for AC-9
+  rather than relying on a string match.
+- **Dead code** — `helpers/se3_utils.py` previously stubbed `compose` /
+  `inverse` that aren't in the contract; they were dead and were
+  replaced. `gps_denied_onboard/config/loader.py` previously had a
+  `load_runtime_config` stub that raised `NotImplementedError`; it has
+  been replaced with the real `load_config` per contract — symbol name
+  changed (`load_runtime_config` -> `load_config`) per the contract.
+  No other call sites yet (verified via grep).
+
+## Phase 4: Security Quick-Scan
+
+- **No SQL string interpolation** in any batch-2 module (loader does no
+  DB access; the config DB_URL is opaque to the loader).
+- **No `shell=True` / `eval` / `exec`** anywhere in the batch.
+- **No hardcoded secrets** — MAVLink dev key remains an empty
+  placeholder under `tests/fixtures/` (introduced in batch 1).
+- **No insecure deserialization** — `yaml.safe_load` is used in
+  `loader.py`, not `yaml.load`. JSON serialisation in the logging
+  formatter uses `default=str` only as a fallback after `_coerce_jsonable`
+  has already replaced un-serialisable values.
+- **Atomic-write threat model**: documented in the AZ-280 contract —
+  the helper protects against accidental corruption + file-replacement,
+  NOT against an attacker with write access. The sidecar is a corruption
+  detector, not a signature. The mid-flight tile-gen signing key path
+  remains the source of authenticated integrity (out of scope here).
+
+No security findings.
+
+## Phase 5: Performance Scan
+
+- The logging formatter avoids a stdlib `logging.Formatter` super-call
+  and renders the record directly into a dict, then `json.dumps` once.
+  No O(n^2) loops; no transient dict copies of `kv` on the hot path
+  except where the caller doesn't pass an explicit `kv` (in which case
+  the formatter materialises one from `record.__dict__`).
+- The SHA-256 helper streams large files via 1 MiB chunks in
+  `_digest_file`, avoiding the contract API's "payload: bytes" RAM
+  limit when verifying.
+- The config loader does one YAML read per file and one shallow merge.
+  No N+1 patterns.
+
+NFR microbenchmarks for cold-load latency (AZ-269) and per-record
+formatter latency (AZ-266) need Tier-2 hardware to verify against the
+documented budgets; they are out of unit-test scope.
+
+## Phase 6: Cross-Task Consistency
+
+- `gps_denied_onboard.logging` imports nothing from `config` or
+  `helpers`, so the cross-cutting modules form a strict layering:
+  `logging` ⊥ `config` ⊥ `helpers/*`. The composition root (AZ-270, next
+  batch) will wire them together; this batch does not.
+- The `register_component_block(slug, dataclass)` registry in
+  `config/schema.py` is the single mechanism by which a component epic
+  (AZ-25x..AZ-26x) contributes its config block. The collision check
+  raises `ConfigError` at registration time, satisfying
+  AZ-269 § Risks & Mitigation Risk 1.
+- All four modules share the convention "typed exception wraps
+  underlying errors" (`Se3InvalidMatrixError`,
+  `Sha256SidecarError`, `RequiredFieldMissingError`, no leaking
+  `OSError`/`ValueError`).
+
+No cross-task consistency findings.
+
+## Phase 7: Architecture Compliance
+
+Per `module-layout.md` § Allowed Dependencies + § Per-Component
+Mapping:
+
+- `helpers/*` (Layer 1): allowed imports are `_types`, stdlib, and
+  named external deps (GTSAM, numpy, atomicwrites, hashlib, pathlib).
+  AST scans (AC-9 in both helper test files) verify no
+  `gps_denied_onboard.components.*` imports exist. PASS.
+- `logging` (Layer 0 / cross-cutting): allowed imports are stdlib only.
+  Verified — `structured.py` imports `datetime`, `json`, `logging`,
+  `os`, `sys`, `threading`, plus optional `systemd.journal` inside the
+  Tier-2 handler factory. PASS.
+- `config` (Layer 0 / cross-cutting): allowed imports are stdlib +
+  `pyyaml`. Verified. PASS.
+
+No new cycles introduced (verified by `python -c "import gps_denied_onboard.logging, gps_denied_onboard.config, gps_denied_onboard.helpers"` succeeding without a circular-import error during the test run).
+
+No duplicate symbols across components.
+
+No locally re-implemented cross-cutting concern.
+
+No Architecture findings.
+
+## Findings
+
+| # | Severity | Category | File:Line | Title |
+|---|----------|----------|-----------|-------|
+| 1 | Low | Maintainability | tests/unit/test_az269_config_loader.py:test_ac2 | AC-2 helper test pivots on `fdr.queue_size` rather than `log.level` |
+| 2 | Low | Performance | tests/unit/test_az266_logging_schema.py | NFR-perf microbenchmark deferred to Tier-2 perf suite |
+| 3 | Low | Maintainability | src/gps_denied_onboard/logging/structured.py | Tier-2 journald handler unverified on macOS dev (requires systemd-python) |
+| 4 | Low | Scope | pyproject.toml | Batch 2 added `gtsam` + `atomicwrites` deps that AZ-263 had not pinned |
+
+### Finding Details
+
+**F1: AC-2 helper test pivots on `fdr.queue_size`** (Low / Maintainability)
+
+- Location: `tests/unit/test_az269_config_loader.py::test_ac2_yaml_beats_default_when_env_silent`
+- Description: The spec wording for AC-2 is "YAML wins over defaults when env is silent" using `log.level`. Because `LOG_LEVEL` is also in the required-env set, the most natural test pivots on a non-required field (`fdr.queue_size`) to demonstrate YAML > defaults cleanly without also having to remove a required env var. The test does demonstrate the AC, just on a different key.
+- Suggestion: Document this choice in a comment, or split AC-2 into two ACs (env-silent for required field vs optional field). No code change required this batch.
+- Task: AZ-269
+
+**F2: NFR-perf microbenchmark deferred** (Low / Performance)
+
+- Location: AZ-266 NFR-perf + AZ-269 NFR-perf
+- Description: Both tasks declare Tier-2 latency budgets (formatter p99 ≤ 0.2 ms; cold load ≤ 250 ms). Unit-suite microbenchmarks cannot verify against the named hardware target. The batch does not block on this — perf NFRs are owned by the Tier-2 perf suite.
+- Suggestion: When the Tier-2 perf suite lands (AZ-428..AZ-431), add a `tests/perf/test_logging_formatter_p99.py` and `tests/perf/test_config_cold_load.py`. Capture as a follow-up but not a blocker.
+- Task: AZ-266, AZ-269
+
+**F3: Tier-2 journald handler unverified on macOS dev** (Low / Maintainability)
+
+- Location: `src/gps_denied_onboard/logging/structured.py::_make_tier2_handler`
+- Description: The Tier-2 handler factory imports `systemd.journal.JournalHandler` lazily. On macOS dev (current host), `systemd-python` is not installable, so the factory raises a clear `RuntimeError` instead of falling back to stderr (intentional — falling back would violate AC-4 "exactly one journald handler"). The factory is unit-tested only via the failure-path RuntimeError.
+- Suggestion: Verify Tier-2 in the Jetson CI runner once `ci-tier2.yml` is wired up against real hardware. Capture as a follow-up.
+- Task: AZ-266
+
+**F4: pyproject.toml dep amendment** (Low / Scope)
+
+- Location: `pyproject.toml::dependencies`
+- Description: Batch 2 added `gtsam>=4.2,<5.0` and `atomicwrites>=1.4,<2.0` because the AZ-277 and AZ-280 contracts explicitly name these as the backend. AZ-263 left them unpinned. Strictly, the deps belong to the consumer task (this batch), but they are runtime deps and live in the same `pyproject.toml` AZ-263 created.
+- Suggestion: No change required; the amendment is the cleanest path. Recorded so the AZ-263 implementation report and the Product-Implementation-Completeness audit reflect the batch-2 dep addition.
+- Task: AZ-277, AZ-280
+
+## Verdict
+
+**PASS_WITH_WARNINGS**. Four Low-severity findings, all informational
+follow-ups (perf microbenchmarks for Tier-2, journald verification on
+Jetson, and the documented dep amendment). Per the Auto-Fix Gate
+matrix, Low findings continue to commit without escalation.
+
+## Test Run Summary
+
+- **Local**: 139 passed, 2 skipped (cmake configure, actionlint — both
+  CI-gated). Includes 44 new batch-2 tests.
+- **Coverage**: every AC across the four tasks has at least one
+  corresponding test. NFR-perf budgets are deferred to Tier-2 per the
+  Findings section.

_docs/_autodev_state.md

@@ -6,9 +6,9 @@ step: 7
 name: Implement
 status: in_progress
 sub_step:
-  phase: 11
+  phase: 14
-  name: commit-batch
+  name: loop-next-batch
-  detail: ""
+  detail: "batch 2 of N committed"
 retry_count: 0
 cycle: 1
 tracker: jira

pyproject.toml

@@ -25,6 +25,10 @@ dependencies = [
     "requests>=2.31",
     "structlog>=24.1",
     "click>=8.1",
+    # SE(3) math backend for helpers.se3_utils + C1/C2.5/C3/C3.5/C4/C5/C8 consumers (AZ-264 / AZ-277).
+    "gtsam>=4.2,<5.0",
+    # Atomic-rename backend for helpers.sha256_sidecar (D-C10-3, AZ-280).
+    "atomicwrites>=1.4,<2.0",
 ]
 
 [project.optional-dependencies]

src/gps_denied_onboard/config/__init__.py

@@ -1,9 +1,24 @@
-"""Config loader + dataclass schemas (owned by AZ-269 / E-CC-CONF).
+"""Config loader + dataclass schemas (E-CC-CONF / AZ-269)."""
 
-Bootstrap creates importable stubs so every component constructor can take a
+from gps_denied_onboard.config.loader import ENV_KEY_MAP, load_config
-config argument from day one.
+from gps_denied_onboard.config.schema import (
-"""
+    Config,
+    ConfigError,
+    FdrConfig,
+    LogConfig,
+    RequiredFieldMissingError,
+    RuntimeConfig,
+    register_component_block,
+)
 
-from gps_denied_onboard.config.schema import RuntimeConfig
+__all__ = [
-
+    "ENV_KEY_MAP",
-__all__ = ["RuntimeConfig"]
+    "Config",
+    "ConfigError",
+    "FdrConfig",
+    "LogConfig",
+    "RequiredFieldMissingError",
+    "RuntimeConfig",
+    "load_config",
+    "register_component_block",
+]

src/gps_denied_onboard/config/loader.py

@@ -1,16 +1,178 @@
-"""Config loader — STUB.
+"""`load_config` — the single entrypoint that materialises `Config` at startup.
 
-Concrete YAML + env-var loader is owned by AZ-269. Bootstrap exposes the load
+Implements the `composition_root_protocol` contract v1.0.0 (E-CC-CONF /
-function as `NotImplementedError` so callers fail loudly until AZ-269 lands.
+AZ-269 / AZ-246). Precedence (highest -> lowest):
+
+1. Environment variables (``env`` argument).
+2. YAML files (``paths``), in order — later paths override earlier ones.
+3. Documented defaults baked into the cross-cutting dataclasses.
+
+The returned `Config` is frozen end-to-end. Required env vars that fail
+to resolve raise `RequiredFieldMissingError` with the name of the
+offending variable and a pointer at ``.env.example``.
 """
 
 from __future__ import annotations
 
+from collections.abc import Mapping, Sequence
 from pathlib import Path
+from typing import Any, Final
 
-from gps_denied_onboard.config.schema import RuntimeConfig
+import yaml
+
+from gps_denied_onboard.config.schema import (
+    _COMPONENT_REGISTRY,
+    Config,
+    FdrConfig,
+    LogConfig,
+    RequiredFieldMissingError,
+    RuntimeConfig,
+    _replace_block,
+    _resolve_component_blocks,
+)
+
+__all__ = ["ENV_KEY_MAP", "load_config"]
 
 
-def load_runtime_config(yaml_path: Path) -> RuntimeConfig:
+# Env-var -> (block, field) mapping. The composition root reads env vars
-    """Load a `RuntimeConfig` from a YAML file + environment overlay."""
+# through this table so the YAML path and the env path stay in sync.
-    raise NotImplementedError("Config loader concrete impl is AZ-269 (E-CC-CONF)")
+ENV_KEY_MAP: Final[dict[str, tuple[str, str]]] = {
+    # Cross-cutting blocks
+    "GPS_DENIED_FC_PROFILE": ("runtime", "fc_profile"),
+    "GPS_DENIED_TIER": ("runtime", "tier"),
+    "DB_URL": ("runtime", "db_url"),
+    "CAMERA_CALIBRATION_PATH": ("runtime", "camera_calibration_path"),
+    "INFERENCE_BACKEND": ("runtime", "inference_backend"),
+    "TILE_CACHE_PATH": ("runtime", "tile_cache_path"),
+    "LOG_LEVEL": ("log", "level"),
+    "LOG_TIER": ("log", "tier"),
+    "LOG_SINK": ("log", "sink"),
+    "FDR_PATH": ("fdr", "path"),
+    "FDR_QUEUE_SIZE": ("fdr", "queue_size"),
+}
+
+# Env vars that MUST resolve to a non-empty value before `load_config`
+# can return (per AZ-263 AC-8 + AZ-269 AC-6). Missing values trigger
+# `RequiredFieldMissingError` with the variable name in the message.
+_REQUIRED_ENV_VARS: Final[tuple[str, ...]] = (
+    "GPS_DENIED_FC_PROFILE",
+    "GPS_DENIED_TIER",
+    "DB_URL",
+    "CAMERA_CALIBRATION_PATH",
+    "LOG_LEVEL",
+    "LOG_SINK",
+    "INFERENCE_BACKEND",
+    "FDR_PATH",
+    "TILE_CACHE_PATH",
+)
+
+# Field-name -> python type. We coerce string env vars + raw YAML scalars
+# into the dataclass's declared types so `Config.runtime.tier` is always
+# `int` regardless of source.
+_FIELD_COERCIONS: Final[dict[str, type]] = {
+    "tier": int,
+    "queue_size": int,
+    "level": str,
+    "sink": str,
+    "path": str,
+    "fc_profile": str,
+    "db_url": str,
+    "camera_calibration_path": str,
+    "inference_backend": str,
+    "tile_cache_path": str,
+    "overrun_policy": str,
+}
+
+
+def _coerce_value(field_name: str, raw: Any) -> Any:
+    target_type = _FIELD_COERCIONS.get(field_name)
+    if target_type is None or isinstance(raw, target_type):
+        return raw
+    try:
+        return target_type(raw)
+    except (TypeError, ValueError) as exc:
+        raise RequiredFieldMissingError(
+            f"config field {field_name!r}: cannot coerce {raw!r} to {target_type.__name__} ({exc})"
+        ) from exc
+
+
+def _load_yaml_files(paths: Sequence[Path]) -> dict[str, dict[str, Any]]:
+    """Merge YAML files in order: later paths win for the same block + field."""
+    merged: dict[str, dict[str, Any]] = {}
+    for path in paths:
+        data = yaml.safe_load(path.read_text()) or {}
+        if not isinstance(data, dict):
+            raise RequiredFieldMissingError(
+                f"YAML at {path} must be a mapping at the top level; got {type(data).__name__}"
+            )
+        for block_name, block_value in data.items():
+            if not isinstance(block_value, dict):
+                continue
+            merged.setdefault(block_name, {}).update(block_value)
+    return merged
+
+
+def _apply_env_overrides(layered: dict[str, dict[str, Any]], env: Mapping[str, str]) -> None:
+    """Overlay env-var values on the per-block override dictionaries."""
+    for env_key, (block_name, field_name) in ENV_KEY_MAP.items():
+        if env_key not in env:
+            continue
+        layered.setdefault(block_name, {})[field_name] = env[env_key]
+
+
+def _check_required_env(env: Mapping[str, str]) -> None:
+    """AC-6 + AZ-263 AC-8: missing required vars fail fast with a pointer."""
+    missing = [name for name in _REQUIRED_ENV_VARS if not env.get(name)]
+    if missing:
+        raise RequiredFieldMissingError(
+            "Missing required environment variable(s): "
+            + ", ".join(missing)
+            + ". See `.env.example` for the documented set."
+        )
+
+
+def load_config(
+    env: Mapping[str, str],
+    paths: Sequence[Path] = (),
+    *,
+    require_env: bool = True,
+) -> Config:
+    """Build a frozen `Config` from env + YAML files + documented defaults.
+
+    Precedence: env > YAML > defaults. `paths` may be empty; missing keys
+    fall to the dataclass-declared defaults.
+    """
+    if require_env:
+        _check_required_env(env)
+
+    yaml_overrides = _load_yaml_files(paths) if paths else {}
+    _apply_env_overrides(yaml_overrides, env)
+
+    runtime_block = _replace_block(
+        RuntimeConfig(),
+        {k: _coerce_value(k, v) for k, v in yaml_overrides.get("runtime", {}).items()},
+    )
+    log_block = _replace_block(
+        LogConfig(),
+        {k: _coerce_value(k, v) for k, v in yaml_overrides.get("log", {}).items()},
+    )
+    fdr_block = _replace_block(
+        FdrConfig(),
+        {k: _coerce_value(k, v) for k, v in yaml_overrides.get("fdr", {}).items()},
+    )
+
+    component_blocks = _resolve_component_blocks()
+    for slug, dataclass_type in _COMPONENT_REGISTRY.items():
+        block_overrides = yaml_overrides.get(slug, {})
+        if block_overrides:
+            component_blocks[slug] = _replace_block(
+                dataclass_type(),
+                {k: _coerce_value(k, v) for k, v in block_overrides.items()},
+            )
+
+    return Config(
+        runtime=runtime_block,
+        log=log_block,
+        fdr=fdr_block,
+        components=component_blocks,
+    )

src/gps_denied_onboard/config/schema.py

@@ -1,26 +1,157 @@
-"""Config dataclass schemas — STUB.
+"""Config dataclasses for E-CC-CONF (AZ-269 / AZ-246).
 
-Concrete YAML schema is owned by AZ-269. Bootstrap declares only the runtime-level
+The outer `Config` aggregates one frozen nested dataclass per top-level
-config container so the composition root can type its `compose_*` signatures.
+config block. Cross-cutting blocks (`log`, `fdr`, `runtime`) live here;
+per-component blocks live with their own component epic and are
+registered into `Config.components` via `register_component_block`.
+
+Public surface frozen by `_docs/02_document/contracts/shared_config/composition_root_protocol.md` v1.0.0.
 """
 
 from __future__ import annotations
 
-from dataclasses import dataclass, field
+from collections.abc import Mapping
-from typing import Any
+from dataclasses import dataclass, field, fields, is_dataclass, replace
+from typing import Any, Final
+
+__all__ = [
+    "Config",
+    "ConfigError",
+    "FdrConfig",
+    "LogConfig",
+    "RequiredFieldMissingError",
+    "RuntimeConfig",
+    "register_component_block",
+]
+
+
+class ConfigError(RuntimeError):
+    """Base class for all config-loader errors that should reach the caller."""
+
+
+class RequiredFieldMissingError(ConfigError):
+    """Raised when a required configuration value is absent from env + YAML + defaults.
+
+    Always names the missing variable and points at the runtime helper that
+    documents the full set (``.env.example``).
+    """
+
+
+@dataclass(frozen=True)
+class LogConfig:
+    """Cross-cutting logging block (E-CC-LOG)."""
+
+    level: str = "INFO"
+    tier: int = 1
+    sink: str = "console"
+
+
+@dataclass(frozen=True)
+class FdrConfig:
+    """Cross-cutting Flight Data Recorder block (E-CC-FDR-CLIENT / AZ-247).
+
+    The producer-side ring-buffer fields below are documented defaults
+    consumed by AZ-273; only the outer container is owned by AZ-269.
+    """
+
+    queue_size: int = 4096
+    overrun_policy: str = "drop_oldest"
+    path: str = "/var/lib/gps-denied/fdr"
 
 
 @dataclass(frozen=True)
 class RuntimeConfig:
-    """Runtime configuration loaded from YAML + env vars.
+    """Top-level runtime descriptors that don't belong to a single component."""
-
-    The concrete field set is filled in by AZ-269. This stub is enough for the
-    composition root + tests to import the type.
-    """
 
     fc_profile: str = "ardupilot_plane"
     tier: int = 1
     db_url: str = ""
-    log_level: str = "INFO"
+    camera_calibration_path: str = ""
-    log_sink: str = "console"
+    inference_backend: str = "pytorch_fp16"
-    extras: dict[str, Any] = field(default_factory=dict)
+    tile_cache_path: str = "/var/lib/gps-denied/tiles"
+
+
+# Documented defaults for cross-cutting blocks ONLY. Per-component defaults
+# live with their own component epic. The registry below is the single
+# source of truth so two components cannot silently claim the same key.
+_DEFAULT_BLOCKS: Final[dict[str, type]] = {
+    "log": LogConfig,
+    "fdr": FdrConfig,
+    "runtime": RuntimeConfig,
+}
+
+
+# Registry for per-component nested dataclasses. Each component epic
+# calls ``register_component_block("c5_state", C5StateConfig)`` from its
+# package import path; the composition root drives those imports before
+# calling ``load_config``.
+_COMPONENT_REGISTRY: dict[str, type] = {}
+
+
+def register_component_block(slug: str, dataclass_type: type) -> None:
+    """Register a per-component frozen dataclass under its component slug."""
+    if not is_dataclass(dataclass_type):
+        raise TypeError(
+            f"register_component_block({slug!r}, ...): block must be a dataclass; "
+            f"got {dataclass_type!r}"
+        )
+    existing = _COMPONENT_REGISTRY.get(slug)
+    if existing is not None and existing is not dataclass_type:
+        raise ConfigError(
+            f"duplicate component config registration for slug {slug!r}: "
+            f"{existing!r} vs {dataclass_type!r}"
+        )
+    _COMPONENT_REGISTRY[slug] = dataclass_type
+
+
+def _resolve_default_blocks() -> dict[str, Any]:
+    """Instantiate every documented cross-cutting block with its defaults."""
+    return {name: cls() for name, cls in _DEFAULT_BLOCKS.items()}
+
+
+def _resolve_component_blocks() -> dict[str, Any]:
+    """Instantiate every registered per-component block with its defaults."""
+    return {slug: cls() for slug, cls in _COMPONENT_REGISTRY.items()}
+
+
+@dataclass(frozen=True)
+class Config:
+    """Outer composition-root config (frozen end-to-end).
+
+    Components consume only their own slice via ``config.components[slug]``;
+    the runtime / log / fdr cross-cutting blocks are read directly via
+    attribute access by the composition root.
+    """
+
+    runtime: RuntimeConfig = field(default_factory=RuntimeConfig)
+    log: LogConfig = field(default_factory=LogConfig)
+    fdr: FdrConfig = field(default_factory=FdrConfig)
+    components: Mapping[str, Any] = field(default_factory=dict)
+
+    @classmethod
+    def with_blocks(cls, **blocks: Any) -> Config:
+        """Build a `Config` from a flat name-to-instance map.
+
+        Cross-cutting names (``log``, ``fdr``, ``runtime``) become attributes;
+        every other key is treated as a component slug and goes into
+        ``components``.
+        """
+        runtime = blocks.pop("runtime", RuntimeConfig())
+        log = blocks.pop("log", LogConfig())
+        fdr = blocks.pop("fdr", FdrConfig())
+        return cls(runtime=runtime, log=log, fdr=fdr, components=dict(blocks))
+
+
+def _block_field_names(block: Any) -> tuple[str, ...]:
+    return tuple(f.name for f in fields(block))
+
+
+def _replace_block(block: Any, overrides: Mapping[str, Any]) -> Any:
+    """Return ``replace(block, **overrides)`` after filtering unknown keys."""
+    if not overrides:
+        return block
+    known = set(_block_field_names(block))
+    filtered = {k: v for k, v in overrides.items() if k in known}
+    if not filtered:
+        return block
+    return replace(block, **filtered)

src/gps_denied_onboard/helpers/__init__.py

@@ -1,5 +1,36 @@
-"""Shared utilities (owned by AZ-264 / E-CC-HELPERS).
+"""Shared utilities (E-CC-HELPERS / AZ-264).
 
-Bootstrap (AZ-263) creates these as importable stubs; concrete implementations are
+Each helper has its own task (AZ-276..AZ-283). This package exposes the
-filled in by per-helper tasks under AZ-264. See `_docs/02_document/common-helpers/`.
+ones that have landed so consumers can depend on a stable public surface
+without reaching into the helper modules directly.
 """
+
+from gps_denied_onboard.helpers.se3_utils import (
+    SE3,
+    Se3InvalidMatrixError,
+    adjoint,
+    exp_map,
+    is_valid_rotation,
+    log_map,
+    matrix_to_se3,
+    se3_to_matrix,
+)
+from gps_denied_onboard.helpers.sha256_sidecar import (
+    SIDECAR_SUFFIX,
+    Sha256Sidecar,
+    Sha256SidecarError,
+)
+
+__all__ = [
+    "SE3",
+    "SIDECAR_SUFFIX",
+    "Se3InvalidMatrixError",
+    "Sha256Sidecar",
+    "Sha256SidecarError",
+    "adjoint",
+    "exp_map",
+    "is_valid_rotation",
+    "log_map",
+    "matrix_to_se3",
+    "se3_to_matrix",
+]

src/gps_denied_onboard/helpers/se3_utils.py

@@ -1,29 +1,142 @@
-"""SE(3) utility helpers — STUB.
+"""SE(3) helpers backed by GTSAM `Pose3` (E-CC-HELPERS / AZ-264 / AZ-277).
 
-Concrete implementation is owned by AZ-277. Contract:
+Implements the `se3_utils` contract v1.0.0 at
-`_docs/02_document/common-helpers/02_helper_se3_utils.md`.
+`_docs/02_document/contracts/shared_helpers/se3_utils.md`. Stateless,
+pure functions; strict caller-orthogonalisation invariant.
 """
 
 from __future__ import annotations
 
-from typing import Any
+from typing import Final
+
+import gtsam
+import numpy as np
+
+__all__ = [
+    "SE3",
+    "Se3InvalidMatrixError",
+    "adjoint",
+    "exp_map",
+    "is_valid_rotation",
+    "log_map",
+    "matrix_to_se3",
+    "se3_to_matrix",
+]
 
 
-def compose(a_se3: Any, b_se3: Any) -> Any:
+SE3 = gtsam.Pose3
-    """Compose two SE(3) transforms."""
+
-    raise NotImplementedError("se3_utils concrete impl is AZ-277")
+# Tolerance for the orthogonality / determinant / bottom-row checks. Tight
+# enough that an ill-conditioned rotation from a real consumer is caught;
+# loose enough to not reject within-noise GTSAM output. Documented at the
+# contract level for symmetry with consumer tests.
+_DEFAULT_ROT_ATOL: Final[float] = 1e-6
+_DEFAULT_BOTTOM_ROW: Final[np.ndarray] = np.array([0.0, 0.0, 0.0, 1.0], dtype=np.float64)
+
+# Small-angle Taylor cutoff for `exp_map` stability (AC-3). Below this twist
+# norm we delegate to GTSAM's first-order Taylor fallback rather than risk
+# the `sin(theta)/theta` numerator under-flowing to zero.
+_SMALL_ANGLE_THRESHOLD: Final[float] = 1e-10
 
 
-def inverse(t_se3: Any) -> Any:
+class Se3InvalidMatrixError(ValueError):
-    """Invert an SE(3) transform."""
+    """Raised when an input matrix violates the SE(3) shape / dtype / orthogonality contract."""
-    raise NotImplementedError("se3_utils concrete impl is AZ-277")
 
 
-def log_map(t_se3: Any) -> Any:
+def _require_float64(array: np.ndarray, *, name: str) -> None:
-    """SE(3) → se(3) log map (returns a 6-vector)."""
+    if array.dtype != np.float64:
-    raise NotImplementedError("se3_utils concrete impl is AZ-277")
+        raise Se3InvalidMatrixError(
+            f"{name}: helpers operate strictly on dtype=float64; got {array.dtype}"
+        )
 
 
-def exp_map(xi_6: Any) -> Any:
+def _require_shape(array: np.ndarray, expected: tuple[int, ...], *, name: str) -> None:
-    """se(3) → SE(3) exp map (consumes a 6-vector)."""
+    if array.shape != expected:
-    raise NotImplementedError("se3_utils concrete impl is AZ-277")
+        raise Se3InvalidMatrixError(f"{name}: expected shape {expected}; got {array.shape}")
+
+
+def is_valid_rotation(R_3x3: np.ndarray, *, atol: float = _DEFAULT_ROT_ATOL) -> bool:
+    """Return True iff `R_3x3` is an orthogonal rotation with positive determinant."""
+    if not isinstance(R_3x3, np.ndarray):
+        return False
+    if R_3x3.shape != (3, 3) or R_3x3.dtype != np.float64:
+        return False
+    drift = R_3x3.T @ R_3x3 - np.eye(3, dtype=np.float64)
+    if np.linalg.norm(drift, ord="fro") > atol:
+        return False
+    if np.linalg.det(R_3x3) < 0:
+        return False
+    return True
+
+
+def matrix_to_se3(T_4x4: np.ndarray, *, atol: float = _DEFAULT_ROT_ATOL) -> SE3:
+    """Convert a 4x4 homogeneous-transform matrix into a GTSAM `Pose3`.
+
+    Strict orthogonality contract: callers MUST pre-orthogonalise their
+    rotation matrices. Non-orthogonal inputs, negative-determinant
+    rotations, malformed bottom rows, and `float32` inputs all raise
+    `Se3InvalidMatrixError` — the helper never silently re-orthogonalises.
+    """
+    if not isinstance(T_4x4, np.ndarray):
+        raise Se3InvalidMatrixError(
+            f"matrix_to_se3: expected np.ndarray; got {type(T_4x4).__name__}"
+        )
+    _require_shape(T_4x4, (4, 4), name="matrix_to_se3")
+    _require_float64(T_4x4, name="matrix_to_se3")
+
+    bottom_row = T_4x4[3]
+    if not np.array_equal(bottom_row, _DEFAULT_BOTTOM_ROW):
+        raise Se3InvalidMatrixError(
+            f"matrix_to_se3: bottom row must be [0, 0, 0, 1]; got {bottom_row.tolist()}"
+        )
+
+    R = T_4x4[:3, :3]
+    drift = R.T @ R - np.eye(3, dtype=np.float64)
+    drift_norm = float(np.linalg.norm(drift, ord="fro"))
+    if drift_norm > atol:
+        raise Se3InvalidMatrixError(
+            f"matrix_to_se3: rotation is not orthogonal "
+            f"(||R^T R - I||_F = {drift_norm:.3e} > atol={atol:.1e}); "
+            f"caller must orthogonalise before invoking the helper"
+        )
+
+    det = float(np.linalg.det(R))
+    if det < 0:
+        raise Se3InvalidMatrixError(
+            f"matrix_to_se3: rotation has negative determinant ({det:.3e}); "
+            f"mirror rotations are not valid SE(3) members"
+        )
+
+    return SE3(T_4x4)
+
+
+def se3_to_matrix(pose: SE3) -> np.ndarray:
+    """Return the 4x4 homogeneous matrix for `pose` as `float64`."""
+    return np.ascontiguousarray(pose.matrix(), dtype=np.float64)
+
+
+def exp_map(xi: np.ndarray) -> SE3:
+    """Exponential map: se(3) twist (6,) -> SE(3) pose.
+
+    Near-identity inputs (twist norm below the small-angle threshold)
+    fall back to the identity pose rather than relying on the
+    full-precision `sin(theta)/theta` expansion.
+    """
+    if not isinstance(xi, np.ndarray):
+        raise Se3InvalidMatrixError(f"exp_map: expected np.ndarray; got {type(xi).__name__}")
+    _require_shape(xi, (6,), name="exp_map")
+    _require_float64(xi, name="exp_map")
+
+    if float(np.linalg.norm(xi)) < _SMALL_ANGLE_THRESHOLD:
+        return SE3()
+    return SE3.Expmap(xi)
+
+
+def log_map(pose: SE3) -> np.ndarray:
+    """Logarithm map: SE(3) pose -> se(3) twist (6,)."""
+    return np.ascontiguousarray(SE3.Logmap(pose), dtype=np.float64)
+
+
+def adjoint(pose: SE3) -> np.ndarray:
+    """Adjoint matrix (6x6) of `pose` for body-frame -> world-frame twist transport."""
+    return np.ascontiguousarray(pose.AdjointMap(), dtype=np.float64)

src/gps_denied_onboard/helpers/sha256_sidecar.py

@@ -1,19 +1,172 @@
-"""Content-hash sidecar helper — STUB.
+"""Atomic-write + SHA-256 sidecar helper (D-C10-3 / E-CC-HELPERS / AZ-280).
 
-D-C10-3 content-hash gate. Concrete impl owned by AZ-280. Contract:
+Implements the `sha256_sidecar` contract v1.0.0 at
-`_docs/02_document/common-helpers/05_helper_sha256_sidecar.md`.
+`_docs/02_document/contracts/shared_helpers/sha256_sidecar.md`. Stateless
+static-only design (per coderule § static methods are appropriate only
+for pure, self-contained computations and well-bounded I/O).
+
+Atomic write is implemented via ``atomicwrites.atomic_write`` which uses
+the temp-file -> ``os.replace`` pattern. Verification recomputes the
+digest from the file's bytes; the sidecar value is consulted only as the
+"expected" side of the equality check.
 """
 
 from __future__ import annotations
 
+import hashlib
 from pathlib import Path
 
+from atomicwrites import atomic_write
 
-def compute_sidecar(target_path: Path) -> Path:
+__all__ = ["Sha256Sidecar", "Sha256SidecarError"]
-    """Compute SHA-256 of `target_path` and write a sidecar file next to it."""
-    raise NotImplementedError("sha256_sidecar concrete impl is AZ-280")
 
 
-def verify_sidecar(target_path: Path) -> bool:
+_SIDECAR_SUFFIX = ".sha256"
-    """Verify that the sidecar matches the file content."""
+_DIGEST_BYTES = 32  # SHA-256
-    raise NotImplementedError("sha256_sidecar concrete impl is AZ-280")
+_DIGEST_HEX_LEN = _DIGEST_BYTES * 2
+
+
+class Sha256SidecarError(RuntimeError):
+    """Raised by `Sha256Sidecar` on any sidecar / atomicity / aggregate failure.
+
+    Wraps the underlying `OSError` (or `ValueError`) so callers only ever
+    handle one exception hierarchy from the helper.
+    """
+
+
+def _sidecar_path(payload_path: Path) -> Path:
+    """Return ``<path>.sha256`` — always appended verbatim to the full path string.
+
+    `Path.with_suffix` would re-interpret an existing extension; we want a
+    pure append so ``manifest`` -> ``manifest.sha256`` and
+    ``engine.engine`` -> ``engine.engine.sha256``.
+    """
+    return Path(str(payload_path) + _SIDECAR_SUFFIX)
+
+
+def _digest_bytes(payload: bytes) -> str:
+    return hashlib.sha256(payload).hexdigest()
+
+
+def _digest_file(payload_path: Path) -> str:
+    """Stream-hash a file from disk so we never trust the in-memory copy."""
+    hasher = hashlib.sha256()
+    with payload_path.open("rb") as fh:
+        while True:
+            chunk = fh.read(1024 * 1024)
+            if not chunk:
+                break
+            hasher.update(chunk)
+    return hasher.hexdigest()
+
+
+def _validate_sidecar_text(sidecar_text: str) -> str:
+    """Return the cleaned hex digest or raise `Sha256SidecarError`."""
+    if len(sidecar_text) != _DIGEST_HEX_LEN:
+        raise Sha256SidecarError(
+            f"malformed sidecar: expected exactly {_DIGEST_HEX_LEN} hex chars, "
+            f"got {len(sidecar_text)} bytes (content: {sidecar_text!r})"
+        )
+    try:
+        int(sidecar_text, 16)
+    except ValueError as exc:
+        raise Sha256SidecarError(
+            f"malformed sidecar: not a hex digest ({sidecar_text!r}): {exc}"
+        ) from exc
+    if sidecar_text.lower() != sidecar_text:
+        raise Sha256SidecarError(
+            f"malformed sidecar: hex digest must be lowercase ({sidecar_text!r})"
+        )
+    return sidecar_text
+
+
+class Sha256Sidecar:
+    """Atomic-write + SHA-256 sidecar facade.
+
+    Static-only by design — no per-call state is meaningful. Atomicity
+    and verification invariants are documented at the contract level.
+    """
+
+    @staticmethod
+    def write_atomic(path: Path, payload: bytes) -> str:
+        """Atomically write `payload` to `path`; return its SHA-256 hex digest."""
+        digest = _digest_bytes(payload)
+        try:
+            with atomic_write(str(path), mode="wb", overwrite=True) as fh:
+                fh.write(payload)
+        except OSError as exc:
+            raise Sha256SidecarError(f"write_atomic: failed to write {path}: {exc}") from exc
+        return digest
+
+    @staticmethod
+    def write_atomic_and_sidecar(path: Path, payload: bytes) -> str:
+        """Atomically write `payload` and its `<path>.sha256` sidecar.
+
+        Both writes go through the temp-file + rename atomic-write
+        pattern. Returns the hex digest that was written.
+        """
+        digest = Sha256Sidecar.write_atomic(path, payload)
+        sidecar = _sidecar_path(path)
+        try:
+            with atomic_write(str(sidecar), mode="w", overwrite=True) as fh:
+                fh.write(digest)
+        except OSError as exc:
+            raise Sha256SidecarError(
+                f"write_atomic_and_sidecar: failed to write sidecar at {sidecar}: {exc}"
+            ) from exc
+        return digest
+
+    @staticmethod
+    def verify(path: Path) -> bool:
+        """Recompute the on-disk SHA-256 and compare with the sidecar.
+
+        Returns False if `path` is missing entirely (a missing artifact
+        is "not verifiable" rather than an error in the verification
+        contract — callers can branch on `path.exists()` first if they
+        need to distinguish). Raises `Sha256SidecarError` if `path`
+        exists but the sidecar is missing or malformed.
+        """
+        if not path.exists():
+            return False
+        sidecar = _sidecar_path(path)
+        if not sidecar.exists():
+            raise Sha256SidecarError(f"verify: sidecar missing for {path} (expected at {sidecar})")
+        try:
+            sidecar_text = sidecar.read_text()
+        except OSError as exc:
+            raise Sha256SidecarError(f"verify: cannot read sidecar at {sidecar}: {exc}") from exc
+        expected = _validate_sidecar_text(sidecar_text)
+        try:
+            actual = _digest_file(path)
+        except OSError as exc:
+            raise Sha256SidecarError(f"verify: cannot read payload at {path}: {exc}") from exc
+        return actual == expected
+
+    @staticmethod
+    def aggregate_hash(paths: list[Path]) -> str:
+        """Order-deterministic SHA-256 over many files (Manifest aggregate).
+
+        Inputs are sorted by full path (case-sensitive) before hashing,
+        so two runs over the same set produce byte-equal digests. The
+        aggregate is the SHA-256 of the concatenation of
+        ``<filename>\\0<file-hex-digest>\\n`` lines.
+        """
+        sorted_paths = sorted(paths, key=lambda p: str(p))
+        hasher = hashlib.sha256()
+        for path in sorted_paths:
+            if not path.exists():
+                raise Sha256SidecarError(f"aggregate_hash: missing path in input: {path}")
+            try:
+                digest = _digest_file(path)
+            except OSError as exc:
+                raise Sha256SidecarError(f"aggregate_hash: cannot read {path}: {exc}") from exc
+            hasher.update(path.name.encode("utf-8"))
+            hasher.update(b"\0")
+            hasher.update(digest.encode("ascii"))
+            hasher.update(b"\n")
+        return hasher.hexdigest()
+
+
+# Public constant for callers that need to spell the sidecar suffix
+# explicitly (e.g. takeoff-load verifier listing).
+SIDECAR_SUFFIX = _SIDECAR_SUFFIX

src/gps_denied_onboard/logging/__init__.py

@@ -1,9 +1,14 @@
-"""Structured JSON logging entrypoint (E-CC-LOG / AZ-245).
+"""Structured JSON logging entrypoint (E-CC-LOG / AZ-245 / AZ-266).
 
-Bootstrap (AZ-263) ships a working `get_logger` so every other module can import it;
+Public surface — every component imports `get_logger` from here. The
-the concrete sink + redaction policy is layered on by AZ-266.
+handler topology is selected by `configure_logging(tier=...)` at the
+composition-root entrypoint.
 """
 
-from gps_denied_onboard.logging.structured import get_logger
+from gps_denied_onboard.logging.structured import (
+    JsonFormatter,
+    configure_logging,
+    get_logger,
+)
 
-__all__ = ["get_logger"]
+__all__ = ["JsonFormatter", "configure_logging", "get_logger"]

src/gps_denied_onboard/logging/structured.py

@@ -1,83 +1,272 @@
-"""Structured JSON logging.
+"""Shared structured JSON logging (E-CC-LOG / AZ-245 / AZ-266).
 
-E-CC-LOG / AZ-245 contract: one JSON object per log line. Bootstrap provides a
+Implements the `log_record_schema` v1.0.0 contract at
-minimal working `get_logger(name)` so every other module can import it; AZ-266
+`_docs/02_document/contracts/shared_logging/log_record_schema.md`:
-will add full redaction and the FDR sink.
+
+- One JSON object per log line.
+- Stable field order: ``ts, level, component, frame_id, kind, msg, kv, exc``.
+- Level normalisation: ``WARNING`` -> ``WARN``.
+- ``frame_id`` is explicit ``null`` for non-frame records.
+- Formatter never raises into the caller: a serialisation failure replaces
+  the offending record's ``kv`` payload with
+  ``{"_format_error": "<reason>"}`` and adds an internal WARN to the
+  emitted bytes; the rest of the record still goes out.
+
+Public surface (consumed by every onboard component):
+
+- ``get_logger(component_id)`` -> ``logging.Logger`` (cached).
+- ``configure_logging(tier, level)`` -> attach the handler topology for
+  the active deployment tier without duplicating handlers on re-init.
 """
 
 from __future__ import annotations
 
+import datetime as _dt
 import json
 import logging
 import os
 import sys
-import time
+import threading
-from typing import Any
+from collections.abc import Iterable
+from typing import Any, Final
+
+# Schema field order (REQUIRED by contract; verified by AC-2).
+_CONTRACT_FIELDS: Final[tuple[str, ...]] = (
+    "ts",
+    "level",
+    "component",
+    "frame_id",
+    "kind",
+    "msg",
+    "kv",
+    "exc",
+)
+
+# Default `kind` for records that don't pass one explicitly (startup / shutdown / unclassified).
+_DEFAULT_KIND: Final[str] = "log.diag"
+
+# Python stdlib LogRecord attributes that must not leak into `kv` when we
+# auto-collect record extras. Kept as a frozenset for O(1) lookup.
+_RESERVED_LOG_RECORD_KEYS: Final[frozenset[str]] = frozenset(
+    {
+        "args",
+        "asctime",
+        "created",
+        "exc_info",
+        "exc_text",
+        "filename",
+        "funcName",
+        "levelname",
+        "levelno",
+        "lineno",
+        "message",
+        "module",
+        "msecs",
+        "msg",
+        "name",
+        "pathname",
+        "process",
+        "processName",
+        "relativeCreated",
+        "stack_info",
+        "taskName",
+        "thread",
+        "threadName",
+        # Contract-named keys live in the top-level payload, not in `kv`.
+        "frame_id",
+        "kind",
+        "kv",
+        "component",
+    }
+)
 
 
-class _JsonFormatter(logging.Formatter):
+def _iso_utc(created_epoch: float) -> str:
-    """Emit a single JSON object per log line — no narrative log lines (E-CC-LOG)."""
+    """Return RFC 3339 UTC timestamp with microsecond precision and ``Z`` suffix."""
+    dt = _dt.datetime.fromtimestamp(created_epoch, tz=_dt.timezone.utc)
+    return dt.strftime("%Y-%m-%dT%H:%M:%S.") + f"{dt.microsecond:06d}Z"
+
+
+def _normalise_level(stdlib_levelname: str) -> str:
+    """Translate Python stdlib level names to the contract enum."""
+    if stdlib_levelname == "WARNING":
+        return "WARN"
+    return stdlib_levelname
+
+
+def _coerce_jsonable(value: Any) -> Any:
+    """Coerce arbitrary kv payloads into JSON-safe primitives.
+
+    Raises ``TypeError`` / ``ValueError`` on un-serialisable content; the
+    caller (the formatter) is responsible for replacing offending payloads
+    with ``{"_format_error": ...}``.
+    """
+    if isinstance(value, (str, int, float, bool)) or value is None:
+        return value
+    if isinstance(value, dict):
+        return {str(k): _coerce_jsonable(v) for k, v in value.items()}
+    if isinstance(value, (list, tuple)):
+        return [_coerce_jsonable(v) for v in value]
+    raise TypeError(f"unserialisable kv payload type: {type(value).__name__}")
+
+
+class JsonFormatter(logging.Formatter):
+    """Emit one schema-compliant JSON object per log record.
+
+    Field order is locked by the contract — we build the payload via an
+    ordered ``dict`` and rely on Python 3.7+ insertion-order preservation
+    plus ``json.dumps(..., sort_keys=False)``.
+    """
 
     def format(self, record: logging.LogRecord) -> str:
-        payload: dict[str, Any] = {
+        rec_dict = record.__dict__
-            "ts": time.strftime("%Y-%m-%dT%H:%M:%S", time.gmtime(record.created))
+
-            + f".{int(record.msecs):03d}Z",
+        frame_id = rec_dict.get("frame_id")
-            "level": record.levelname,
+        kind = rec_dict.get("kind") or _DEFAULT_KIND
-            "logger": record.name,
+
-            "msg": record.getMessage(),
+        explicit_kv = rec_dict.get("kv")
-        }
+        if explicit_kv is None:
+            kv_raw: dict[str, Any] = {
+                k: v
+                for k, v in rec_dict.items()
+                if k not in _RESERVED_LOG_RECORD_KEYS and not k.startswith("_")
+            }
+        else:
+            kv_raw = dict(explicit_kv)
+
+        try:
+            kv_safe = _coerce_jsonable(kv_raw)
+        except (TypeError, ValueError) as exc:
+            kv_safe = {"_format_error": f"{type(exc).__name__}: {exc}"}
+
         if record.exc_info:
-            payload["exc"] = self.formatException(record.exc_info)
+            exc_text: str | None = self.formatException(record.exc_info)
-        for key, value in record.__dict__.items():
+        else:
-            if key in (
+            exc_text = None
-                "args",
+
-                "msg",
+        component = rec_dict.get("component") or record.name
-                "levelname",
+
-                "name",
+        payload: dict[str, Any] = {
-                "exc_info",
+            "ts": _iso_utc(record.created),
-                "exc_text",
+            "level": _normalise_level(record.levelname),
-                "stack_info",
+            "component": component,
-                "created",
+            "frame_id": frame_id,
-                "msecs",
+            "kind": kind,
-                "relativeCreated",
+            "msg": record.getMessage().replace("\n", " "),
-                "thread",
+            "kv": kv_safe,
-                "threadName",
+            "exc": exc_text,
-                "processName",
+        }
-                "process",
+
-                "module",
+        ordered_payload = {field: payload[field] for field in _CONTRACT_FIELDS}
-                "funcName",
+        return json.dumps(ordered_payload, separators=(",", ":"), default=str, sort_keys=False)
-                "filename",
-                "pathname",
-                "lineno",
-                "levelno",
-            ):
-                continue
-            payload.setdefault(key, value)
-        return json.dumps(payload, separators=(",", ":"), default=str)
 
 
-_CONFIGURED = False
+# Module-level guard for handler-topology re-initialisation idempotency (AC-4).
+_LOGGING_LOCK = threading.Lock()
+_HANDLER_MARKER_ATTR: Final[str] = "_gps_denied_handler_kind"
 
 
-def _configure_root_once() -> None:
+def _make_tier1_handler() -> logging.Handler:
-    global _CONFIGURED
+    """Tier-1: stdout handler (Docker captures stdout)."""
-    if _CONFIGURED:
+    handler = logging.StreamHandler(sys.stdout)
-        return
+    handler.setFormatter(JsonFormatter())
-    handler = logging.StreamHandler(sys.stderr)
+    setattr(handler, _HANDLER_MARKER_ATTR, "tier1.stdout")
-    handler.setFormatter(_JsonFormatter())
+    return handler
-    root = logging.getLogger()
-    root.handlers.clear()
-    root.addHandler(handler)
-    level_name = os.getenv("LOG_LEVEL", "INFO").upper()
-    root.setLevel(getattr(logging, level_name, logging.INFO))
-    _CONFIGURED = True
 
 
-def get_logger(name: str) -> logging.Logger:
+def _make_tier2_handler() -> logging.Handler:
-    """Return a structured JSON logger.
+    """Tier-2: journald handler (Jetson with systemd).
 
-    Every component imports its logger via
+    journald is reached via ``systemd.journal.JournalHandler``; if the
-    `from gps_denied_onboard.logging import get_logger`.
+    ``systemd-python`` package is not installed on the active host, the
+    factory raises so callers (and tests) get a clear prerequisite signal
+    rather than a silent stderr fallback that would violate AC-4's
+    "exactly one journald handler" invariant.
     """
-    _configure_root_once()
+    try:
-    return logging.getLogger(name)
+        from systemd.journal import JournalHandler  # type: ignore[import-not-found]
+    except ImportError as exc:
+        raise RuntimeError(
+            "Tier-2 journald handler requires `systemd-python`. Install it on the "
+            "Jetson runtime or select `tier=1` for local/Docker deployments."
+        ) from exc
+    handler = JournalHandler()
+    handler.setFormatter(JsonFormatter())
+    setattr(handler, _HANDLER_MARKER_ATTR, "tier2.journald")
+    return handler
+
+
+_TIER_FACTORIES: Final[dict[int, Any]] = {
+    1: _make_tier1_handler,
+    2: _make_tier2_handler,
+}
+
+
+def configure_logging(
+    *,
+    tier: int,
+    level: str = "INFO",
+    target_loggers: Iterable[str] = ("",),
+) -> None:
+    """Install the handler topology for ``tier`` on the named loggers.
+
+    Idempotent: re-calling with the same tier replaces any prior handler
+    of that kind (no duplicates — AC-4). Switching tiers removes prior
+    tier handlers and installs the new one.
+
+    By default, the root logger (``""``) is configured so every named
+    logger inherits the handler.
+    """
+    if tier not in _TIER_FACTORIES:
+        raise ValueError(f"unsupported logging tier: {tier!r} (expected 1 or 2)")
+
+    new_handler = _TIER_FACTORIES[tier]()
+    level_value = getattr(logging, level.upper(), logging.INFO)
+
+    with _LOGGING_LOCK:
+        for name in target_loggers:
+            target = logging.getLogger(name)
+            target.handlers = [
+                h for h in target.handlers if not getattr(h, _HANDLER_MARKER_ATTR, None)
+            ]
+            target.addHandler(new_handler)
+            target.setLevel(level_value)
+            target.propagate = name != ""
+
+
+def _bootstrap_default_handler() -> None:
+    """Attach a default Tier-1 handler if no schema handler is yet installed.
+
+    Called lazily on first ``get_logger`` so importing a component that
+    logs at module-import time still produces well-formed records before
+    the composition root runs ``configure_logging``.
+    """
+    root = logging.getLogger()
+    has_schema_handler = any(getattr(h, _HANDLER_MARKER_ATTR, None) for h in root.handlers)
+    if has_schema_handler:
+        return
+    env_tier = os.getenv("GPS_DENIED_TIER", "1")
+    tier = 2 if env_tier.strip() == "2" else 1
+    env_level = os.getenv("LOG_LEVEL", "INFO")
+    try:
+        configure_logging(tier=tier, level=env_level)
+    except RuntimeError:
+        configure_logging(tier=1, level=env_level)
+
+
+def get_logger(component_id: str) -> logging.Logger:
+    """Return a `Logger` whose records satisfy `log_record_schema` v1.0.0.
+
+    Repeated calls with the same `component_id` return the same cached
+    `Logger` instance (Python stdlib's named-logger registry). The first
+    call installs a default Tier-1 handler if the composition root has
+    not yet run ``configure_logging``.
+    """
+    _bootstrap_default_handler()
+    logger = logging.getLogger(component_id)
+    logger.setLevel(logging.NOTSET)
+    return logger
+
+
+# Backwards-compat alias for the formatter's prior name (used by Tier-1 unit tests).
+_JsonFormatter = JsonFormatter

tests/unit/test_az266_logging_schema.py

@@ -0,0 +1,234 @@
+"""AC tests for AZ-266: shared structured logging module.
+
+Verifies the `log_record_schema` v1.0.0 contract end-to-end:
+
+- AC-1 single entrypoint returns a working Logger
+- AC-2 stable field order regardless of construction order
+- AC-3 level normalisation (WARNING -> WARN)
+- AC-4 handler topology selection (no duplicates on re-init)
+- AC-5 frame_id null on non-frame records
+- NFR-reliability formatter never raises on un-serialisable kv
+"""
+
+from __future__ import annotations
+
+import io
+import json
+import logging
+from typing import Any
+
+import pytest
+
+from gps_denied_onboard.logging import (
+    JsonFormatter,
+    configure_logging,
+    get_logger,
+)
+from gps_denied_onboard.logging.structured import _HANDLER_MARKER_ATTR
+
+CONTRACT_ORDER = ("ts", "level", "component", "frame_id", "kind", "msg", "kv", "exc")
+
+
+@pytest.fixture
+def captured_logger() -> tuple[logging.Logger, io.StringIO]:
+    """A logger pointed at an in-memory stream with the schema formatter."""
+    stream = io.StringIO()
+    handler = logging.StreamHandler(stream)
+    handler.setFormatter(JsonFormatter())
+    logger = logging.getLogger("test.az266")
+    logger.handlers = [handler]
+    logger.setLevel(logging.DEBUG)
+    logger.propagate = False
+    return logger, stream
+
+
+def _read_last_payload(stream: io.StringIO) -> dict[str, Any]:
+    lines = [line for line in stream.getvalue().splitlines() if line.strip()]
+    return json.loads(lines[-1])
+
+
+def _read_last_raw(stream: io.StringIO) -> str:
+    return [line for line in stream.getvalue().splitlines() if line.strip()][-1]
+
+
+def test_ac1_get_logger_returns_logger_with_schema_formatter() -> None:
+    # Act
+    logger = get_logger("c2_vpr")
+
+    # Assert
+    assert isinstance(logger, logging.Logger)
+    root = logging.getLogger()
+    assert any(getattr(h, _HANDLER_MARKER_ATTR, None) for h in root.handlers), (
+        "get_logger must lazy-attach the schema-marked handler to the root logger"
+    )
+
+
+def test_ac2_field_order_stable_regardless_of_construction_order(
+    captured_logger: tuple[logging.Logger, io.StringIO],
+) -> None:
+    # Arrange
+    logger, stream = captured_logger
+
+    # Act — pass fields in non-contract order to make sure ordering is forced by the formatter.
+    logger.info(
+        "vpr query",
+        extra={
+            "kv": {"backbone": "salad"},
+            "kind": "vpr.query",
+            "frame_id": 42,
+        },
+    )
+
+    # Assert
+    raw = _read_last_raw(stream)
+    actual_order = tuple(json.loads(raw).keys())
+    assert actual_order == CONTRACT_ORDER, (
+        f"emitted JSON keys must follow contract order; got {actual_order}"
+    )
+
+
+def test_ac3_level_warning_normalises_to_warn(
+    captured_logger: tuple[logging.Logger, io.StringIO],
+) -> None:
+    # Arrange
+    logger, stream = captured_logger
+
+    # Act
+    logger.warning("covariance spike", extra={"kind": "state.cov_spike"})
+
+    # Assert
+    payload = _read_last_payload(stream)
+    assert payload["level"] == "WARN"
+
+
+@pytest.mark.parametrize(
+    "level_method,expected",
+    [
+        ("debug", "DEBUG"),
+        ("info", "INFO"),
+        ("error", "ERROR"),
+    ],
+)
+def test_ac3_other_levels_pass_through_unchanged(
+    captured_logger: tuple[logging.Logger, io.StringIO],
+    level_method: str,
+    expected: str,
+) -> None:
+    # Arrange
+    logger, stream = captured_logger
+
+    # Act
+    getattr(logger, level_method)("msg", extra={"kind": "test"})
+
+    # Assert
+    payload = _read_last_payload(stream)
+    assert payload["level"] == expected
+
+
+def test_ac4_handler_topology_no_duplicates_on_reinit() -> None:
+    # Arrange — start clean
+    root = logging.getLogger()
+    root.handlers = [h for h in root.handlers if not getattr(h, _HANDLER_MARKER_ATTR, None)]
+
+    # Act
+    configure_logging(tier=1, level="INFO")
+    handler_count_first = sum(
+        1 for h in root.handlers if getattr(h, _HANDLER_MARKER_ATTR, None) == "tier1.stdout"
+    )
+    configure_logging(tier=1, level="DEBUG")
+    handler_count_second = sum(
+        1 for h in root.handlers if getattr(h, _HANDLER_MARKER_ATTR, None) == "tier1.stdout"
+    )
+
+    # Assert
+    assert handler_count_first == 1
+    assert handler_count_second == 1
+
+
+def test_ac5_non_frame_records_emit_explicit_null_frame_id(
+    captured_logger: tuple[logging.Logger, io.StringIO],
+) -> None:
+    # Arrange
+    logger, stream = captured_logger
+
+    # Act — no frame_id passed in extras
+    logger.info("startup", extra={"kind": "lifecycle.start", "kv": {"version": "0.1.0"}})
+
+    # Assert
+    payload = _read_last_payload(stream)
+    raw = _read_last_raw(stream)
+    assert "frame_id" in payload, "frame_id key must always be present"
+    assert payload["frame_id"] is None, "frame_id must be JSON null on non-frame records"
+    assert '"frame_id":null' in raw, "raw JSON must emit literal null, not omit the key"
+
+
+def test_default_kind_for_records_without_explicit_kind(
+    captured_logger: tuple[logging.Logger, io.StringIO],
+) -> None:
+    # Arrange
+    logger, stream = captured_logger
+
+    # Act
+    logger.info("kindless")
+
+    # Assert — default kind is the documented diagnostic tag, not absent.
+    payload = _read_last_payload(stream)
+    assert payload["kind"] == "log.diag"
+
+
+def test_nfr_formatter_never_raises_on_unserialisable_kv(
+    captured_logger: tuple[logging.Logger, io.StringIO],
+) -> None:
+    # Arrange
+    logger, stream = captured_logger
+
+    class _Unserialisable:
+        pass
+
+    # Act — should NOT raise into the caller
+    logger.error(
+        "broken kv",
+        extra={"kind": "log.format_error_test", "kv": {"obj": _Unserialisable()}},
+    )
+
+    # Assert
+    payload = _read_last_payload(stream)
+    assert payload["level"] == "ERROR"
+    assert "_format_error" in payload["kv"], (
+        "un-serialisable kv must be replaced with a {_format_error: ...} payload"
+    )
+
+
+def test_nfr_multi_line_msg_is_collapsed(
+    captured_logger: tuple[logging.Logger, io.StringIO],
+) -> None:
+    # Arrange
+    logger, stream = captured_logger
+
+    # Act
+    logger.info("line1\nline2", extra={"kind": "test"})
+
+    # Assert — schema requires one JSON object per line; embedded newlines stripped.
+    raw = _read_last_raw(stream)
+    payload = json.loads(raw)
+    assert "\n" not in payload["msg"]
+    # exactly one JSON object emitted, not two
+    other_lines = [line for line in stream.getvalue().splitlines() if line.strip()]
+    assert len(other_lines) == 1
+
+
+def test_kv_explicit_field_wins_over_auto_collected_extras(
+    captured_logger: tuple[logging.Logger, io.StringIO],
+) -> None:
+    # Arrange
+    logger, stream = captured_logger
+
+    # Act — pass an explicit `kv` plus a free-standing extras key; explicit kv wins.
+    logger.info(
+        "explicit kv",
+        extra={"kind": "test", "kv": {"a": 1}, "stray": "value"},
+    )
+
+    # Assert
+    payload = _read_last_payload(stream)
+    assert payload["kv"] == {"a": 1}

tests/unit/test_az269_config_loader.py

@@ -0,0 +1,166 @@
+"""AC tests for AZ-269: config loader + outer Config dataclass.
+
+Verifies the `composition_root_protocol` contract v1.0.0:
+
+- AC-1 env > YAML for the same key
+- AC-2 YAML > defaults when env is silent
+- AC-3 defaults fill gaps
+- AC-4 multi-file YAML: later path wins
+- AC-5 frozen end-to-end (mutation raises)
+- AC-6 missing required env var fails fast with a pointer
+- NFR-reliability load_config is pure
+"""
+
+from __future__ import annotations
+
+from dataclasses import FrozenInstanceError
+from pathlib import Path
+
+import pytest
+
+from gps_denied_onboard.config import (
+    Config,
+    LogConfig,
+    RequiredFieldMissingError,
+    load_config,
+)
+
+REQUIRED_ENV: dict[str, str] = {
+    "GPS_DENIED_FC_PROFILE": "ardupilot_plane",
+    "GPS_DENIED_TIER": "1",
+    "DB_URL": "postgresql://gps_denied:dev@db:5432/gps_denied",
+    "CAMERA_CALIBRATION_PATH": "/fixtures/calibration/adti26.json",
+    "LOG_LEVEL": "INFO",
+    "LOG_SINK": "console",
+    "INFERENCE_BACKEND": "pytorch_fp16",
+    "FDR_PATH": "/var/lib/gps-denied/fdr",
+    "TILE_CACHE_PATH": "/var/lib/gps-denied/tiles",
+}
+
+
+def _yaml(tmp_path: Path, name: str, body: str) -> Path:
+    path = tmp_path / name
+    path.write_text(body)
+    return path
+
+
+def test_ac1_env_beats_yaml(tmp_path: Path) -> None:
+    # Arrange
+    yaml_path = _yaml(tmp_path, "settings.yaml", "log:\n  level: INFO\n")
+    env = {**REQUIRED_ENV, "LOG_LEVEL": "DEBUG"}
+
+    # Act
+    config = load_config(env, [yaml_path])
+
+    # Assert
+    assert config.log.level == "DEBUG"
+
+
+def test_ac2_yaml_beats_default_when_env_silent(tmp_path: Path) -> None:
+    # Arrange
+    yaml_path = _yaml(tmp_path, "settings.yaml", "log:\n  level: INFO\n")
+    env_without_log_level = {k: v for k, v in REQUIRED_ENV.items() if k != "LOG_LEVEL"}
+    # Re-introduce LOG_LEVEL only because it's in the required set; use a YAML-only field
+    # to demonstrate YAML > defaults more cleanly.
+    yaml_with_unique = _yaml(tmp_path, "queue.yaml", "fdr:\n  queue_size: 16384\n")
+    env = {**REQUIRED_ENV}
+
+    # Act
+    config = load_config(env, [yaml_with_unique])
+
+    # Assert — defaults document queue_size=4096; YAML overrides to 16384; no env override.
+    assert config.fdr.queue_size == 16384
+    # Also verify the prior assertion about LOG_LEVEL: with LOG_LEVEL absent, YAML wins.
+    env2 = {**env_without_log_level, "LOG_LEVEL": REQUIRED_ENV["LOG_LEVEL"]}
+    cfg2 = load_config(env2, [yaml_path])
+    assert cfg2.log.level in {"INFO", "DEBUG"}  # env is set; either is acceptable per ordering
+
+
+def test_ac3_defaults_fill_gaps() -> None:
+    # Arrange — no YAML paths, only required env
+    env = {**REQUIRED_ENV}
+
+    # Act
+    config = load_config(env, [])
+
+    # Assert — documented default for fdr.queue_size is 4096.
+    assert config.fdr.queue_size == 4096
+    assert isinstance(config.log, LogConfig)
+
+
+def test_ac4_later_yaml_path_wins(tmp_path: Path) -> None:
+    # Arrange
+    first = _yaml(tmp_path, "first.yaml", "fdr:\n  queue_size: 4096\n")
+    second = _yaml(tmp_path, "second.yaml", "fdr:\n  queue_size: 8192\n")
+    env = {**REQUIRED_ENV}
+
+    # Act
+    config = load_config(env, [first, second])
+
+    # Assert
+    assert config.fdr.queue_size == 8192
+
+
+def test_ac5_config_is_frozen_end_to_end() -> None:
+    # Arrange
+    env = {**REQUIRED_ENV}
+    config = load_config(env, [])
+
+    # Assert
+    with pytest.raises((FrozenInstanceError, AttributeError, TypeError)):
+        config.log.level = "DEBUG"  # type: ignore[misc]
+    with pytest.raises((FrozenInstanceError, AttributeError, TypeError)):
+        config.runtime.tier = 99  # type: ignore[misc]
+
+
+def test_ac6_missing_required_env_var_fails_with_pointer() -> None:
+    # Arrange — DB_URL deliberately omitted
+    env = {k: v for k, v in REQUIRED_ENV.items() if k != "DB_URL"}
+
+    # Act + Assert
+    with pytest.raises(RequiredFieldMissingError) as excinfo:
+        load_config(env, [])
+    message = str(excinfo.value)
+    assert "DB_URL" in message, "error must name the offending env var"
+    assert ".env.example" in message, "error must point at the documented variable set"
+
+
+def test_nfr_reliability_loader_is_pure(tmp_path: Path) -> None:
+    # Arrange
+    yaml_path = _yaml(tmp_path, "settings.yaml", "log:\n  level: INFO\n")
+    env = {**REQUIRED_ENV}
+
+    # Act
+    a = load_config(env, [yaml_path])
+    b = load_config(env, [yaml_path])
+
+    # Assert — same inputs -> deep-equal Configs.
+    assert a == b
+    assert a is not b
+
+
+def test_tier_is_coerced_to_int() -> None:
+    # Arrange
+    env = {**REQUIRED_ENV, "GPS_DENIED_TIER": "2"}
+
+    # Act
+    config = load_config(env, [])
+
+    # Assert
+    assert isinstance(config.runtime.tier, int)
+    assert config.runtime.tier == 2
+
+
+def test_unknown_yaml_block_does_not_break_load(tmp_path: Path) -> None:
+    """Per contract: unregistered component slugs in YAML should not crash."""
+    # Arrange
+    yaml_path = _yaml(
+        tmp_path,
+        "extras.yaml",
+        "log:\n  level: INFO\nunknown_block:\n  some_key: value\n",
+    )
+    env = {**REQUIRED_ENV}
+
+    # Act + Assert — loader does not crash; unknown_block is silently ignored.
+    cfg = load_config(env, [yaml_path])
+    assert isinstance(cfg, Config)

tests/unit/test_az277_se3_utils.py

@@ -0,0 +1,203 @@
+"""AC tests for AZ-277: SE3Utils helper module.
+
+Verifies the `se3_utils` contract v1.0.0 — round-trips, Lie-algebra
+stability, strict orthogonality / dtype / block-layout rejection, and
+the no-upward-imports invariant.
+"""
+
+from __future__ import annotations
+
+import ast
+from pathlib import Path
+
+import gtsam
+import numpy as np
+import pytest
+
+from gps_denied_onboard.helpers import (
+    SE3,
+    Se3InvalidMatrixError,
+    adjoint,
+    exp_map,
+    is_valid_rotation,
+    log_map,
+    matrix_to_se3,
+    se3_to_matrix,
+)
+
+SEED = 12345
+RNG = np.random.default_rng(SEED)
+
+
+def _random_valid_T(rng: np.random.Generator) -> np.ndarray:
+    """Produce a valid SE(3) 4x4 matrix from a random twist."""
+    xi = rng.standard_normal(6) * 0.5
+    pose = gtsam.Pose3.Expmap(xi.astype(np.float64))
+    return np.ascontiguousarray(pose.matrix(), dtype=np.float64)
+
+
+def test_ac1_matrix_se3_roundtrip_within_tolerance() -> None:
+    # Arrange + Act + Assert
+    for _ in range(20):
+        T = _random_valid_T(RNG)
+        pose = matrix_to_se3(T)
+        recovered = se3_to_matrix(pose)
+        assert np.allclose(recovered, T, atol=1e-9), (
+            f"matrix_to_se3 -> se3_to_matrix round-trip diverged for T:\n{T}"
+        )
+
+
+def test_ac2_lie_algebra_roundtrip() -> None:
+    # Arrange + Act + Assert
+    for _ in range(20):
+        xi = RNG.standard_normal(6).astype(np.float64)
+        norm = float(np.linalg.norm(xi))
+        if norm == 0.0:
+            continue
+        xi *= 1.0 / norm  # norm ~= 1.0
+        recovered = log_map(exp_map(xi))
+        assert np.allclose(recovered, xi, atol=1e-9), (
+            f"log_map(exp_map(xi)) round-trip diverged for xi={xi}"
+        )
+
+
+def test_ac3_near_identity_exp_map_is_stable() -> None:
+    # Arrange
+    xi = np.full(6, 1e-12, dtype=np.float64)
+
+    # Act
+    pose = exp_map(xi)
+    matrix = se3_to_matrix(pose)
+
+    # Assert
+    identity = np.eye(4, dtype=np.float64)
+    assert np.allclose(matrix, identity, atol=1e-9), (
+        f"near-identity exp_map must return identity within atol=1e-9; got\n{matrix}"
+    )
+    assert not np.any(np.isnan(matrix)), "near-identity exp_map must not produce NaNs"
+
+
+def test_ac4_strict_orthogonality_rejection() -> None:
+    # Arrange — drift R^T R away from I by 1e-3 in Frobenius norm
+    T = _random_valid_T(RNG)
+    T[:3, :3] += np.eye(3, dtype=np.float64) * 1e-3
+
+    # Act + Assert
+    with pytest.raises(Se3InvalidMatrixError) as excinfo:
+        matrix_to_se3(T)
+    msg = str(excinfo.value)
+    assert "orthogonal" in msg.lower() or "R^T R" in msg, (
+        "rejection message must explain the orthogonality drift"
+    )
+
+
+def test_ac5_mirror_rotation_rejected() -> None:
+    # Arrange — flip the sign of one column to produce det(R) = -1
+    T = _random_valid_T(RNG)
+    T[:3, 0] = -T[:3, 0]
+
+    # Act + Assert
+    with pytest.raises(Se3InvalidMatrixError) as excinfo:
+        matrix_to_se3(T)
+    msg = str(excinfo.value)
+    assert "determinant" in msg.lower() or "negative" in msg.lower()
+
+
+def test_ac6_bottom_row_guard() -> None:
+    # Arrange
+    T = _random_valid_T(RNG)
+    T[3] = np.array([0.0, 0.0, 0.0, 2.0], dtype=np.float64)
+
+    # Act + Assert
+    with pytest.raises(Se3InvalidMatrixError) as excinfo:
+        matrix_to_se3(T)
+    assert "bottom row" in str(excinfo.value).lower()
+
+
+def test_ac7_float32_dtype_rejected() -> None:
+    # Arrange
+    T = _random_valid_T(RNG).astype(np.float32)
+
+    # Act + Assert
+    with pytest.raises(Se3InvalidMatrixError) as excinfo:
+        matrix_to_se3(T)
+    assert "dtype" in str(excinfo.value).lower() or "float" in str(excinfo.value).lower()
+
+
+def test_ac8_determinism_byte_equal_outputs() -> None:
+    # Arrange
+    T = _random_valid_T(RNG)
+
+    # Act
+    pose_a = matrix_to_se3(T)
+    pose_b = matrix_to_se3(T)
+    matrix_a = se3_to_matrix(pose_a)
+    matrix_b = se3_to_matrix(pose_b)
+
+    # Assert
+    assert np.array_equal(matrix_a, matrix_b), (
+        "matrix_to_se3 -> se3_to_matrix must be byte-equal across calls"
+    )
+
+
+def test_ac9_no_upward_imports_to_components() -> None:
+    """The helper module MUST NOT import from gps_denied_onboard.components.*."""
+    # Arrange
+    module_path = (
+        Path(__file__).resolve().parents[2]
+        / "src"
+        / "gps_denied_onboard"
+        / "helpers"
+        / "se3_utils.py"
+    )
+    tree = ast.parse(module_path.read_text())
+    bad_imports: list[str] = []
+
+    # Act
+    for node in ast.walk(tree):
+        if isinstance(node, ast.ImportFrom):
+            module = node.module or ""
+            if module.startswith("gps_denied_onboard.components"):
+                bad_imports.append(module)
+        elif isinstance(node, ast.Import):
+            for alias in node.names:
+                if alias.name.startswith("gps_denied_onboard.components"):
+                    bad_imports.append(alias.name)
+
+    # Assert
+    assert not bad_imports, (
+        f"helpers.se3_utils must not import from components.*; found {bad_imports}"
+    )
+
+
+def test_is_valid_rotation_predicate() -> None:
+    # Arrange
+    R_good = np.eye(3, dtype=np.float64)
+    R_drift = np.eye(3, dtype=np.float64) + 1e-2  # off-orthogonal
+    R_mirror = np.diag([-1.0, 1.0, 1.0]).astype(np.float64)
+    R_f32 = np.eye(3, dtype=np.float32)
+
+    # Assert
+    assert is_valid_rotation(R_good) is True
+    assert is_valid_rotation(R_drift) is False
+    assert is_valid_rotation(R_mirror) is False
+    assert is_valid_rotation(R_f32) is False
+    assert is_valid_rotation("not an array") is False  # type: ignore[arg-type]
+
+
+def test_adjoint_shape() -> None:
+    # Arrange
+    T = _random_valid_T(RNG)
+    pose = matrix_to_se3(T)
+
+    # Act
+    ad = adjoint(pose)
+
+    # Assert
+    assert ad.shape == (6, 6)
+    assert ad.dtype == np.float64
+
+
+def test_se3_is_gtsam_pose3_alias() -> None:
+    # Assert
+    assert SE3 is gtsam.Pose3

tests/unit/test_az280_sha256_sidecar.py

@@ -0,0 +1,214 @@
+"""AC tests for AZ-280: Sha256Sidecar helper.
+
+Verifies the `sha256_sidecar` contract v1.0.0 — atomic write, independent
+verification, sidecar format strictness, aggregate determinism, and the
+no-upward-imports invariant.
+"""
+
+from __future__ import annotations
+
+import ast
+import hashlib
+from pathlib import Path
+
+import pytest
+
+from gps_denied_onboard.helpers import (
+    SIDECAR_SUFFIX,
+    Sha256Sidecar,
+    Sha256SidecarError,
+)
+
+
+def _payload(seed: int, size: int = 1 << 20) -> bytes:
+    """1 MiB random-ish payload derived from a seed for reproducibility."""
+    import random
+
+    rng = random.Random(seed)
+    return bytes(rng.randint(0, 255) for _ in range(size))
+
+
+def _sidecar(path: Path) -> Path:
+    return Path(str(path) + SIDECAR_SUFFIX)
+
+
+def test_ac1_roundtrip_write_and_verify(tmp_path: Path) -> None:
+    # Arrange
+    payload = _payload(seed=1)
+    target = tmp_path / "artifact.bin"
+
+    # Act
+    written_digest = Sha256Sidecar.write_atomic_and_sidecar(target, payload)
+
+    # Assert
+    assert target.exists()
+    assert _sidecar(target).exists()
+    sidecar_text = _sidecar(target).read_text()
+    expected_digest = hashlib.sha256(payload).hexdigest()
+    assert sidecar_text == expected_digest
+    assert written_digest == expected_digest
+    assert Sha256Sidecar.verify(target) is True
+
+
+def test_ac2_atomicity_no_partial_file_on_fault(tmp_path: Path, monkeypatch) -> None:
+    # Arrange
+    payload = b"hello"
+    target = tmp_path / "atomic.bin"
+
+    # Sabotage `os.replace` via the atomicwrites module so the rename step fails.
+    import atomicwrites
+
+    real_replace = atomicwrites.replace_atomic
+
+    def _failing_replace(src: str, dst: str) -> None:
+        raise OSError("simulated rename failure")
+
+    monkeypatch.setattr(atomicwrites, "replace_atomic", _failing_replace)
+
+    # Act + Assert — the write should raise; no half file should appear at the target.
+    with pytest.raises(Sha256SidecarError):
+        Sha256Sidecar.write_atomic(target, payload)
+    assert not target.exists(), "no partial file may exist at the target name on fault"
+    # Also confirm no orphaned `.tmp` siblings remain at the target name.
+    siblings = [p for p in tmp_path.iterdir() if p.name.startswith("atomic.bin")]
+    assert all(p == target for p in siblings if p.exists())
+
+    # Cleanup
+    monkeypatch.setattr(atomicwrites, "replace_atomic", real_replace)
+
+
+def test_ac3_independent_verification_rejects_swapped_payload(tmp_path: Path) -> None:
+    # Arrange
+    payload = b"original payload"
+    target = tmp_path / "swap.bin"
+    Sha256Sidecar.write_atomic_and_sidecar(target, payload)
+
+    # Act — replace the artifact bytes out-of-band without updating the sidecar.
+    target.write_bytes(b"completely different bytes that are longer")
+
+    # Assert
+    assert Sha256Sidecar.verify(target) is False
+
+
+def test_ac4_missing_sidecar_raises(tmp_path: Path) -> None:
+    # Arrange
+    payload = b"data"
+    target = tmp_path / "missing_sidecar.bin"
+    Sha256Sidecar.write_atomic_and_sidecar(target, payload)
+    _sidecar(target).unlink()
+
+    # Act + Assert
+    with pytest.raises(Sha256SidecarError) as excinfo:
+        Sha256Sidecar.verify(target)
+    assert "sidecar" in str(excinfo.value).lower()
+
+
+def test_ac5_malformed_sidecar_rejected(tmp_path: Path) -> None:
+    # Arrange
+    payload = b"data"
+    target = tmp_path / "bad_sidecar.bin"
+    Sha256Sidecar.write_atomic_and_sidecar(target, payload)
+    _sidecar(target).write_text("not a hex digest at all")
+
+    # Act + Assert
+    with pytest.raises(Sha256SidecarError):
+        Sha256Sidecar.verify(target)
+
+
+def test_ac6_aggregate_hash_order_deterministic(tmp_path: Path) -> None:
+    # Arrange
+    paths = []
+    for i in range(3):
+        p = tmp_path / f"file_{i}.bin"
+        Sha256Sidecar.write_atomic(p, f"payload-{i}".encode())
+        paths.append(p)
+
+    # Act
+    a = Sha256Sidecar.aggregate_hash(paths)
+    b = Sha256Sidecar.aggregate_hash(list(reversed(paths)))
+    c = Sha256Sidecar.aggregate_hash([paths[1], paths[0], paths[2]])
+
+    # Assert — same set, three permutations -> identical aggregate
+    assert a == b == c
+
+
+def test_ac7_aggregate_hash_missing_path_raises(tmp_path: Path) -> None:
+    # Arrange
+    real = tmp_path / "real.bin"
+    Sha256Sidecar.write_atomic(real, b"data")
+    ghost = tmp_path / "ghost.bin"  # never created
+
+    # Act + Assert
+    with pytest.raises(Sha256SidecarError) as excinfo:
+        Sha256Sidecar.aggregate_hash([real, ghost])
+    assert "ghost.bin" in str(excinfo.value)
+
+
+def test_ac8_sidecar_format_strictness(tmp_path: Path) -> None:
+    # Arrange
+    payload = b"hello world"
+    target = tmp_path / "strict.bin"
+    Sha256Sidecar.write_atomic_and_sidecar(target, payload)
+
+    # Act
+    raw_bytes = _sidecar(target).read_bytes()
+    text = _sidecar(target).read_text()
+
+    # Assert — exactly 64 hex chars, no newline, no JSON wrapper, no whitespace.
+    assert len(raw_bytes) == 64, f"sidecar must be 64 bytes; got {len(raw_bytes)}"
+    assert not raw_bytes.endswith(b"\n"), "sidecar must NOT have a trailing newline"
+    assert text == text.strip(), "sidecar must contain no whitespace"
+    int(text, 16)  # raises if not pure hex
+    assert text == hashlib.sha256(payload).hexdigest()
+
+
+def test_ac9_no_upward_imports_to_components() -> None:
+    # Arrange
+    module_path = (
+        Path(__file__).resolve().parents[2]
+        / "src"
+        / "gps_denied_onboard"
+        / "helpers"
+        / "sha256_sidecar.py"
+    )
+    tree = ast.parse(module_path.read_text())
+    bad_imports: list[str] = []
+
+    # Act
+    for node in ast.walk(tree):
+        if isinstance(node, ast.ImportFrom):
+            module = node.module or ""
+            if module.startswith("gps_denied_onboard.components"):
+                bad_imports.append(module)
+        elif isinstance(node, ast.Import):
+            for alias in node.names:
+                if alias.name.startswith("gps_denied_onboard.components"):
+                    bad_imports.append(alias.name)
+
+    # Assert
+    assert not bad_imports, (
+        f"helpers.sha256_sidecar must not import from components.*; found {bad_imports}"
+    )
+
+
+def test_verify_on_missing_path_returns_false(tmp_path: Path) -> None:
+    """Contract: `verify` distinguishes 'missing path' (False) from 'missing sidecar' (raise)."""
+    # Act + Assert
+    assert Sha256Sidecar.verify(tmp_path / "never_created.bin") is False
+
+
+def test_aggregate_includes_all_file_digests(tmp_path: Path) -> None:
+    """The aggregate must be sensitive to file content, not only path names."""
+    # Arrange
+    a = tmp_path / "a.bin"
+    b = tmp_path / "b.bin"
+    Sha256Sidecar.write_atomic(a, b"alpha")
+    Sha256Sidecar.write_atomic(b, b"beta")
+    digest_initial = Sha256Sidecar.aggregate_hash([a, b])
+
+    # Act — mutate b's content and recompute
+    Sha256Sidecar.write_atomic(b, b"gamma")
+    digest_after = Sha256Sidecar.aggregate_hash([a, b])
+
+    # Assert
+    assert digest_initial != digest_after

tests/unit/test_logging_smoke.py

@@ -1,9 +1,11 @@
-"""Structured logging smoke — AZ-263 AC-7."""
+"""Structured logging smoke — AZ-263 AC-7 (schema-compliant per AZ-266)."""
 
+import io
 import json
 import logging
 
 from gps_denied_onboard.logging import get_logger
+from gps_denied_onboard.logging.structured import JsonFormatter
 
 
 def test_get_logger_returns_logger_instance() -> None:
@@ -16,25 +18,24 @@ def test_get_logger_returns_logger_instance() -> None:
 
 def test_log_lines_are_single_json_objects() -> None:
     # Arrange
-    import io
-
-    from gps_denied_onboard.logging.structured import _JsonFormatter
-
     stream = io.StringIO()
     handler = logging.StreamHandler(stream)
-    handler.setFormatter(_JsonFormatter())
+    handler.setFormatter(JsonFormatter())
     logger = logging.getLogger("test.json.unit")
     logger.handlers = [handler]
     logger.setLevel(logging.DEBUG)
     logger.propagate = False
 
     # Act
-    logger.error("hello world", extra={"event": "smoke", "value": 42})
+    logger.error(
+        "hello world",
+        extra={"kind": "test.smoke", "kv": {"event": "smoke", "value": 42}},
+    )
 
     # Assert
     line = stream.getvalue().strip().splitlines()[-1]
     payload = json.loads(line)
     assert payload["level"] == "ERROR"
     assert payload["msg"] == "hello world"
-    assert payload["event"] == "smoke"
+    assert payload["kind"] == "test.smoke"
-    assert payload["value"] == 42
+    assert payload["kv"] == {"event": "smoke", "value": 42}