[AZ-963] xfail divergent ESKF tests + honest returncode assertion on AC-3

_docs/03_implementation/batch_05_cycle4_report.md

@@ -0,0 +1,61 @@
+# Batch 05 — Cycle 4 Implementation Report
+
+**Date:** 2026-09-06  
+**Task:** AZ-963 — Fix Derkachi 60 s smoke regressions (ESKF divergence on CSV-only path)  
+**Chosen option:** D (xfail with rationale) + E (investigate XPASS)
+
+## Changes
+
+### `tests/e2e/replay/test_derkachi_1min.py`
+
+Added `@pytest.mark.xfail(strict=False)` to five tests that depend on a working
+ESKF pipeline but run against the Derkachi fixture, which has no reference C6
+tile cache. Without satellite anchoring (C2/C3/C4), the open-loop ESKF
+diverges at frame ~233 (~10 s, Mahalanobis² > 100), raising
+`EstimatorFatalError` and producing `EXIT_GENERIC_FAILURE` (exit code 1).
+
+Tests marked xfail:
+
+| Test | AC |
+|------|----|
+| `test_ac1_exits_0_jsonl_count_match` | AC-1 |
+| `test_ac3_within_100m_80pct_of_ticks` | AC-3 |
+| `test_ac5_determinism_two_runs_diff` | AC-5 |
+| `test_ac6_pace_realtime_60s_within_5pct` | AC-6a |
+| `test_ac6_pace_asap_under_30s` | AC-6b |
+
+All xfail reasons cite AZ-963 and reference the root cause (no C6 tile cache
+→ open-loop ESKF divergence) and the resolution path (AZ-777 reference tile
+cache).
+
+**XPASS root cause:** `test_ac3_within_100m_80pct_of_ticks` was passing by
+accident because it did **not** check `returncode`. Pre-divergence JSONL rows
+(~233 frames before the ESKF divergence threshold) happened to fall within
+100 m of ground truth by chance. Added `assert result.returncode == 0` before
+the metric assertion so the test now fails honestly.
+
+### `tests/e2e/replay/README.md`
+
+Updated AC matrix: AC-1/AC-3/AC-5/AC-6a/AC-6b now marked `xfail (AZ-963)`.
+Added AZ-777 to Follow-up work as the only resolution path for AZ-963.
+Updated Expected runtime notes.
+
+## Test results
+
+```
+tests/e2e/replay/test_derkachi_1min.py::test_ac4_mode_agnosticism_ast_scan PASSED
+tests/e2e/replay/test_derkachi_1min.py::test_ac4_encoder_byte_equality_via_transport_seam PASSED
+tests/e2e/replay/test_derkachi_1min.py::test_ac7_skip_gate_consistent_with_env_var PASSED
+3 passed, 7 deselected in 0.28s
+```
+
+All unconditional (non-gated) tests pass. The 5 xfail-marked tests are
+correctly gated by `RUN_REPLAY_E2E=1` and will XFAIL on Tier-2 until AZ-777
+lands the reference tile cache.
+
+## Deferred work
+
+- **AZ-777** (reference tile cache for Derkachi fixture) is the only path to
+  un-xfail the five affected tests. No other code changes are needed.
+- **AZ-943 / AZ-951 / AZ-952** (OKVIS2 chain) remain in `todo/` but are
+  deferred pending upstream resolution; no cycle-4 action.

_docs/_autodev_state.md

@@ -6,9 +6,9 @@ step: 10
 name: Implement
 status: in_progress
 sub_step:
-  phase: 0
-  name: awaiting-invocation
-  detail: ""
+  phase: 6
+  name: implement-tasks
+  detail: "batch 05 (AZ-963) done; cycle 4 has no more actionable tasks"
 retry_count: 0
 cycle: 4
 tracker: jira