# ADR 0034: Lossless replay and diagnostic observation boundary

Date: 2026-07-30
Status: accepted and implemented

## Decision

The accepted K1 local-surface algorithm consumes one normalized, read-only
source view. Two immutable source schemas are admitted:

- camera-aligned `missioncore.e10-lidar-replay-pack/v1`;
- native-cadence, field-retaining `missioncore.lidar-replay-pack/v2`.

The normalized view carries exact source pack identity, artifact SHA-256,
session identity, representation, schema, native point offsets, map-frame XYZ,
host-monotonic timing and nearest-pose age. A replay-pack-v2 source additionally
retains RGBI/intensity provenance. The derivative never rewrites or disguises
one source as the other.

The lossless v2 builder uses two bounded passes over raw capture evidence. The
first pass freezes frame counts and scalar header/timing contracts. The second
pass preallocates and fills numeric arrays one decoded frame at a time, failing
closed if the source differs between passes. The strict reader decompresses
each NPZ member once before repeated integrity, field and logical-content
validation. Repeated on-demand decompression inside a frame loop is forbidden.

## Diagnostic observation derivative

E51 is separate from the persistent reconstruction and the E34 short-TTL
occupied/unknown layer. It may publish:

- temporal motion candidates derived from a bounded centroid history;
- current near-occupied proximity candidates from admitted E32 range;
- camera-owned semantics and semantic provenance;
- explicit current/held freshness and evidence conflict.

It may not publish:

- a dynamic object class;
- a collision state;
- free space from missing points;
- numeric semantic confidence when the upstream contract has none;
- command, navigation or safety authority.

A map-frame jump candidate rejects motion publication. Held evidence cannot
publish current proximity. Collision remains unavailable until the physical
vehicle body and LiDAR mount/extrinsic geometry are separately bound and
qualified.

## Resource boundary

All full-session Mac execution is sequential. The current 14-inch 2023 MacBook
Pro has 18 GiB RAM; replay build, strict validation, local-surface build and
test execution are never intentionally overlapped. Docker is not part of this
path. Port `8000` remains the canonical running Mission Core service.

## Accepted evidence

Full native replay:

```text
lidar-replay-pack-8fc0fb418578b8ee2ac88d502d2acbc63ae533437a9da14f1a9f9d8916f613ce
```

- 4,570 LiDAR frames;
- 4,598 pose frames;
- 10,751,258 points;
- exact live/replay equivalence passed;
- pose coverage 100%.

Full v2 local surface:

```text
k1-local-surface-61a0307497b1e9b32d5521f59aa853bce22d81def7ca4d3fc81273a4162e6d22
```

- 4,570/4,570 valid;
- zero stale-pose, insufficient-surface or fit-failure frames;
- pose-binding age 20.6421 ms p95.

E51:

```text
e51-motion-semantic-1abb7eb9940608fc5af95a1f318cadfbc42ac2412a8662b6622e000e03da1555
```

- 4,489/4,489 frames;
- 2,119,302/2,119,302 current occupied point rows preserved;
- 0.4148 ms frame-processing p95;
- 0.2969 MiB process peak-RSS growth;
- all acceptance checks passed.