NPAMP-SPATIAL — Physical-World Spatial State on the Spatial Channel (companion to draft-bubblefish-npamp-02)¶

Status: DRAFT companion specification. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in BCP 14 (RFC 2119, RFC 8174) when, and only when, they appear in all capitals, as shown here. This document defines an application interface over the N-PAMP Spatial channel 0x0013: how robotics and IoT peers exchange high-frequency physical-world state — coordinate frames, rigid-body transforms, pose, kinematic state, and occupancy — and how a peer queries another peer's current spatial state. It builds on the core specification (draft-bubblefish-npamp-02, the "core specification") and on the deterministic-CBOR and correlation conventions of NPAMP-DISC (40_discovery.md); it does not redefine either. It consumes only code points the core specification reserves for the channel's application frames and introduces no change to the core wire format. Spatial primitives follow the ROS coordinate-frame conventions REP-103 (units and coordinate conventions) and REP-105 (coordinate frame tree). The core specification governs: on any disagreement between this document and the core specification, the core specification is authoritative.

1. Scope¶

1.1 In scope¶

This document specifies, over the Spatial channel 0x0013 of the N-PAMP core specification:

A set of Spatial-channel application frame types, drawn from the channel application-frame namespace that begins at 0x0100 (core specification §4.6);
Deterministic-CBOR bodies for coordinate-frame definition (REP-105 tree nodes), timestamped rigid-body transforms (REP-105 tree edges), pose (position + orientation, optional covariance) of a tracked body, kinematic state (twist: linear + angular velocity, optional covariance), and occupancy-grid patches (2D/2.5D physical-world occupancy);
A request/reply spatial query by which one peer retrieves another peer's current frame tree and last-known body state, correlated by an identifier; and
A structured error model for the spatial exchange itself.

The one-way state frames model a high-frequency, best-effort stream; the query/reply pair is the authoritative "current state" mechanism (§6, §7).

1.2 Not in scope¶

This document does NOT:

Define, mandate, or bind any cryptographic material to the High or Sovereign profile. The Spatial channel is enabled only at the High profile or higher; the cryptographic suite and operational internals bound to a profile are governed by the core specification's profile negotiation, not by this document. This companion defines an application interface only.
Change any field of the 36-octet core frame header, any reserved all-channel frame type (0x0001–0x000A), the future-core reserved band, the companion-extension band, or the extension-TLV encoding; it carries no extension TLV and claims none of the TLV code points the core specification reserves.
Define a rate, cadence, sampling interval, or timing parameter. "High-frequency" is the channel registry's characterization of the traffic class, not a wire parameter; this document states no cadence and manufactures none.
Define global-map georeferencing beyond carrying an Earth-fixed (ECEF) or local ENU coordinate-frame declaration as an ordinary frame node (§5.1); it defines no datum, projection, or geodetic transform.
Define occupancy-cell compression beyond the two cell encodings signaled in §5.5 (raw and run-length over the same cell domain).
Carry any foreign agent protocol. The Spatial channel is a native core channel, not a Bridge carriage class; it does not build on NPAMP-BRIDGE and encapsulates no external protocol.
Define a domain-specific robot model, kinematic solver, or hardware profile. This interface is generic: it carries frames, transforms, poses, twists, and occupancy for arbitrary robotics/IoT endpoints and interprets none of them mechanically.

2. Relationship to the core specification and the profile gate¶

The Spatial channel 0x0013 is registered by the core specification with name Spatial, purpose "Physical-world state for robotics and IoT (high-frequency)", minimum profile High, and direction Multi-stream (core specification §5, Core Channel Registry; interface reference ../channels/0013_spatial.md). This document does not alter any of those registry values.

Profile gate. The Spatial channel MUST be enabled only at the High profile or higher — that is, at High and Sovereign — and MUST NOT be enabled at the Standard profile (core specification §5, min-profile rule). A peer operating below the High profile MUST NOT advertise, send, or accept Spatial frames. A peer that receives a Spatial frame while the negotiated profile is below High MUST treat it as a profile violation (SPATIAL_ERROR code ProfileTooLow, §7, where a channel is in use) or drop it. This document adds no cryptographic behavior of its own; the crypto suite bound to the High or Sovereign profile is the core specification's, referenced here and not restated.

Advertisement gate. A peer that did not advertise the Spatial channel during the handshake (core specification §5) MUST NOT receive Spatial frames; frames on an unadvertised Spatial channel MUST be dropped.

Multi-stream directionality. Spatial is bidirectional and MAY carry concurrent traffic over multiple transport streams within the channel's stream family (core specification §5). Each peer maintains an independent per-direction sequence space and independent per-direction traffic keys. The per-direction sequence space orders frames within a direction; it does not correlate a reply to a request — §6 defines that. Either peer MAY originate a spatial query.

Correlation and error conventions by reference. This document reuses the deterministic-CBOR payload container and the correlation discipline established by NPAMP-DISC (40_discovery.md §4) and does not restate them beyond the adaptations in §4 and §6: a reply echoes its request's correlation identifier verbatim, and replies are matched to requests by that identifier rather than by frame sequence number.

3. Spatial-channel frame types¶

The core specification's application-frame namespace begins at 0x0100 within each channel (core specification §4.6). Under draft-02 the per-channel frame-type space is partitioned into four bands: 0x0000–0x000A reserved all-channel control frames; 0x000B–0x002F reserved for future core use; 0x0030–0x00FF the companion-extension band; and 0x0100–0xFFFF the channel application frames. This document places every Spatial operation frame in the 0x0100+ application band.

Type	Name	Reply	Purpose
`0x0100`	FRAME_DEF	None	Define or replace a coordinate frame and its parent edge (a REP-105 tree node).
`0x0101`	TRANSFORM	None	Timestamped rigid-body transform: the pose of `child_frame` expressed in `coord_frame` (a REP-105 tree edge).
`0x0102`	POSE_UPDATE	None	Timestamped pose (position + orientation, optional covariance) of a tracked body in a named frame.
`0x0103`	STATE_DELTA	None	Timestamped twist (linear + angular velocity, optional covariance) of a tracked body.
`0x0104`	OCCUPANCY_UPDATE	None	Timestamped occupancy-grid patch (2D/2.5D occupancy) in a named frame.
`0x0105`	SPATIAL_QUERY	SPATIAL_SNAPSHOT or SPATIAL_ERROR	Request the responder's current frame tree and/or last-known state for named bodies.
`0x0106`	SPATIAL_SNAPSHOT	None	Successful reply to SPATIAL_QUERY: a coherent snapshot of frames and poses at a stamp; correlation echoes the query.
`0x0107`	SPATIAL_ERROR	None	Structured failure reply; correlation echoes the originating query.

The reserved all-channel frame types (PING 0x0001, PONG 0x0002, CLOSE 0x0003, CLOSE_ACK 0x0004, ERROR 0x0005, KEY_UPDATE 0x0006, and the remainder enumerated in core specification §4.6) retain their core meaning on the Spatial channel. An implementation MUST NOT reuse them for Spatial application traffic, MUST NOT define Spatial application semantics in the reserved all-channel band, the future-core band (0x000B–0x002F), or the companion-extension band (0x0030–0x00FF), and MUST place every Spatial application frame at or above 0x0100.

Frames 0x0100–0x0104 are one-way, best-effort, high-frequency state streams (fire-and-forget); a receiver MUST NOT reply to them. Only the 0x0105/0x0106/0x0107 triple is a correlated request/reply exchange.

4. Frame payload encoding¶

4.1 Payload container¶

A Spatial frame's payload (the octets after the 36-octet core frame header and any extension TLVs, and before the AEAD tag) is a single deterministically encoded CBOR object as defined by core specification §4.5 and §11.9 (deterministic CBOR, RFC 8949). The payload MUST be a CBOR map whose keys are the unsigned integers defined in §4.2 and §5 for the relevant frame type. A sender MUST produce the deterministic encoding (core specification §11.9): byte-identical output for identical input, with the canonical key ordering and shortest-form integer encoding RFC 8949 §4.2 requires. A receiver MUST reject (SPATIAL_ERROR, code MalformedPayload) any Spatial frame whose payload is not a valid deterministic-CBOR map, or whose payload omits a required key or carries a key of the wrong CBOR major type.

Spatial bodies are carried in the frame payload, not in extension TLVs. This document defines and consumes no extension-TLV tag, and therefore claims none of the TLV code points the core specification reserves.

A receiver MUST ignore an unrecognized integer key it encounters in a Spatial payload map whose key is not negative, so that later revisions of this document MAY add fields without breaking a conformant receiver. A receiver MUST reject (SPATIAL_ERROR, code MalformedPayload) a payload that carries a negative integer key it does not recognize, reserving the negative key space for forward-incompatible additions. This is the identical forward-compatibility rule NPAMP-DISC §4.1 defines.

4.2 Common envelope fields¶

Every Spatial payload map carries the following fields. Integer keys are given in parentheses.

Field (key)	CBOR type	Meaning
`frame_kind` (0)	Unsigned int	MUST equal the frame-header Frame Type (`0x0100`–`0x0107`). A receiver MUST reject (SPATIAL_ERROR, code `KindMismatch`) a payload whose `frame_kind` contradicts the frame-header Frame Type.
`stamp` (1)	Int (int64)	Capture time, nanoseconds since the Unix epoch, on the SI-second base (REP-103). A monotonic capture source is RECOMMENDED; a receiver MUST NOT assume the sender's clock is wall-clock synchronized to its own, and uses `stamp` only for the newest-wins ordering of §6.
`corr` (2)	Byte string (1–64 B)	Correlation identifier. Present and non-empty on SPATIAL_QUERY, and echoed verbatim on SPATIAL_SNAPSHOT and SPATIAL_ERROR. Absent on the one-way frames `0x0100`–`0x0104`.

A SPATIAL_QUERY MUST carry a corr that is non-empty and unique among the originating peer's outstanding queries on the Spatial channel in that direction. A SPATIAL_SNAPSHOT and a SPATIAL_ERROR MUST echo the originating query's corr verbatim. A receiver MUST match each reply to its originating query by corr, not by frame sequence number, exactly as NPAMP-DISC §4.2 requires. The one-way frames 0x0100–0x0104 MUST omit corr.

5. Spatial bodies¶

All geometry follows REP-103: coordinate frames are right-handed; body-fixed axes are x-forward, y-left, z-up; geographic frames use ENU (x-east, y-north, z-up); units are SI (metres, metres per second, radians, radians per second); orientation is expressed as a unit quaternion (REP-103's preferred rotation representation over Euler angles); and angular velocity is expressed about the fixed axes (X, Y, Z). A covariance matrix is a row-major 6×6 matrix ordered (x, y, z, rotX, rotY, rotZ) — the REP-103 pose-covariance convention (a 36-element float64 array). Each of the following bodies carries the common envelope (§4.2) in addition to its own fields; the tables below list only the body-specific keys.

5.1 FRAME_DEF (`0x0100`) — REP-105 tree node¶

Field (key)	CBOR type	Required	Meaning
`coord_frame` (3)	Text string	Yes	This frame's identifier (for example `base_link`).
`parent_frame` (4)	Text string	No	Parent frame identifier. Absent means this frame is a tree root. Enforces the REP-105 single-parent rule: each frame has exactly one parent.
`frame_class` (5)	Unsigned int	No	Advisory hint at the frame's REP-105 role: `0` body/base, `1` odom (continuous, may drift), `2` map (non-continuous, non-drifting), `3` earth/ECEF, `4` sensor, `5` world/other. The tree edge, not this hint, is authoritative.
`epoch` (6)	Unsigned int	Yes	Monotonically non-decreasing counter for `coord_frame`. A FRAME_DEF whose `epoch` is strictly greater than the one held replaces the prior definition; one whose `epoch` is less than or equal is ignored (reorder- and duplicate-safe).

A receiver MUST reject (SPATIAL_ERROR, code FrameTreeConflict) a FRAME_DEF that would give a frame a second live parent, or that would close a cycle, so that the REP-105 frame tree remains a single-parent acyclic tree.

5.2 TRANSFORM (`0x0101`) — timestamped tree edge¶

Field (key)	CBOR type	Required	Meaning
`coord_frame` (3)	Text string	Yes	The reference (parent) frame the transform is expressed in.
`child_frame` (4)	Text string	Yes	The frame being located relative to `coord_frame`.
`position` (5)	Array of 3 float64	Yes	Translation `(x, y, z)` in metres, on REP-103 axes.
`orientation` (6)	Array of 4 float64	Yes	Unit quaternion `(x, y, z, w)`; the last element is the scalar part `w` (REP-103 preferred rotation).
`pose_cov` (7)	Array of 36 float64	No	Row-major 6×6 covariance, order `(x, y, z, rotX, rotY, rotZ)`. Absence means the covariance is unknown, NOT that it is zero.

5.3 POSE_UPDATE (`0x0102`)¶

Field (key)	CBOR type	Required	Meaning
`coord_frame` (3)	Text string	Yes	The frame the pose is expressed in.
`body_id` (4)	Byte string (1–64 B)	Yes	Opaque identifier of the tracked body in the sender's namespace.
`position` (5)	Array of 3 float64	Yes	Position `(x, y, z)` in metres.
`orientation` (6)	Array of 4 float64	Yes	Unit quaternion `(x, y, z, w)`.
`pose_cov` (7)	Array of 36 float64	No	Row-major 6×6 covariance as in §5.2. Absence means unknown, not zero.
`seq` (8)	Unsigned int	No	Per-body sample counter, enabling gap detection on a lossy high-frequency stream.

5.4 STATE_DELTA (`0x0103`) — twist¶

Field (key)	CBOR type	Required	Meaning
`coord_frame` (3)	Text string	Yes	The frame the velocities are expressed in (REP-105 recommends the odom frame for locally sensed motion).
`body_id` (4)	Byte string (1–64 B)	Yes	Opaque identifier of the tracked body.
`linear` (5)	Array of 3 float64	Yes	Linear velocity `(vx, vy, vz)` in metres per second.
`angular` (6)	Array of 3 float64	Yes	Angular velocity about the fixed axes `(X, Y, Z)` in radians per second (REP-103 fixed-axis convention for angular rates).
`twist_cov` (7)	Array of 36 float64	No	Row-major 6×6 covariance, order `(x, y, z, rotX, rotY, rotZ)`. Absence means unknown, not zero.
`seq` (8)	Unsigned int	No	Per-body sample counter.

5.5 OCCUPANCY_UPDATE (`0x0104`)¶

Field (key)	CBOR type	Required	Meaning
`coord_frame` (3)	Text string	Yes	The frame the grid origin is expressed in.
`resolution` (4)	float64	Yes	Cell edge length in metres per cell.
`width` (5)	Unsigned int	Yes	Number of cells along the grid x-axis.
`height` (6)	Unsigned int	Yes	Number of cells along the grid y-axis.
`origin` (7)	2-element array: [Array of 3 float64, Array of 4 float64]	Yes	Pose of the grid's `(0,0)` cell in `coord_frame`: element 0 is position `(x, y, z)`, element 1 is the orientation quaternion `(x, y, z, w)`.
`encoding` (8)	Unsigned int	Yes	Cell encoding: `0` raw (one signed byte per cell, value `-1` unknown or `0..100` occupancy percent), `1` run-length over the same signed-byte cell domain.
`cells` (9)	Byte string	Yes	Cell payload per `encoding`, laid out row-major from the origin cell (REP-103 x then y). For `encoding` `0` the length MUST equal `width × height`; for `encoding` `1` the payload MUST decode to exactly `width × height` cells. A payload that does not satisfy this MUST be rejected (SPATIAL_ERROR, code `MalformedPayload`).

5.6 SPATIAL_QUERY (`0x0105`)¶

A SPATIAL_QUERY carries the common envelope (§4.2, with a non-empty corr unique among the requester's outstanding Spatial queries in that direction) and an OPTIONAL conjunctive filter:

Field (key)	CBOR type	Meaning
`want_frames` (3)	Boolean	If true, the snapshot includes the responder's current frame tree (as FRAME_DEF-equivalent records). Absent or false means the frame tree is not requested.
`body_ids` (4)	Array of byte string	If present, the snapshot includes the last-known pose and state for exactly these bodies; absent means all bodies the responder currently tracks.
`cursor` (5)	Byte string	Present only when continuing a paginated snapshot; echoes an opaque continuation token from a prior SPATIAL_SNAPSHOT (§5.7).

A filter is conjunctive: a record is returned only if it satisfies every present filter field. A SPATIAL_QUERY with no filter field requests the responder's whole current spatial state.

5.7 SPATIAL_SNAPSHOT (`0x0106`)¶

A SPATIAL_SNAPSHOT carries the common envelope (§4.2, echoing the query's corr) and:

Field (key)	CBOR type	Meaning
`frames` (3)	Array of FRAME_DEF-body maps (§5.1)	The responder's current frame tree. Present only when the query set `want_frames` true.
`poses` (4)	Array of POSE_UPDATE-body maps (§5.3)	The last-known pose for each requested body, possibly empty.
`states` (5)	Array of STATE_DELTA-body maps (§5.4)	The last-known twist for each requested body. OPTIONAL; a responder that does not retain twist state omits this field.
`complete` (6)	Boolean	True if the snapshot is the entire matching set; false if the responder paginated and more SPATIAL_SNAPSHOT frames follow, bearing the same `corr`.
`cursor` (7)	Byte string	Present only when `complete` is false; an opaque continuation token the requester echoes in a follow-up SPATIAL_QUERY (`cursor`, key 5) to retrieve the next page.

When a responder paginates, it emits one or more SPATIAL_SNAPSHOT frames with complete false and a cursor, followed by a final SPATIAL_SNAPSHOT with complete true. The responder MUST reject (SPATIAL_ERROR, code StaleCursor) a cursor it no longer recognizes. An empty snapshot is a single SPATIAL_SNAPSHOT with empty poses (and, if want_frames was set, empty frames) and complete true.

6. Correlation, operation, and state model¶

6.1 Correlation¶

A SPATIAL_QUERY MUST carry a non-empty corr unique among the requester's outstanding queries on the Spatial channel in that direction. SPATIAL_SNAPSHOT and SPATIAL_ERROR MUST echo it verbatim.
A receiver MUST match a reply to its request by corr, NOT by frame sequence number. This is required under the channel's concurrent Multi-stream operation, where replies on different streams need not arrive in query order.
The one-way frames 0x0100–0x0104 MUST omit corr, and a receiver MUST NOT reply to them.

6.2 Receiver state model¶

A receiver maintains an association-scoped spatial store, keyed by coord_frame for the frame tree and by (coord_frame, body_id) for body state:

FRAME_DEF establishes or replaces a tree edge by epoch: a FRAME_DEF whose epoch is strictly greater than the one held for that coord_frame replaces it; one whose epoch is less than or equal is ignored. This makes frame definitions reorder- and duplicate-safe, and it preserves the REP-105 single-parent acyclic tree (a FRAME_DEF that would introduce a second live parent or a cycle is rejected, §5.1).
TRANSFORM updates the timestamped transform on a tree edge.
POSE_UPDATE and STATE_DELTA update the last-known state of a body by newest stamp: a receiver MUST ignore a sample whose stamp is less than or equal to the last-applied stamp for that body, so that a late or duplicated sample on a lossy high-frequency stream does not overwrite a newer one.

6.3 Best-effort streams versus authoritative query¶

The one-way frames 0x0100–0x0104 are best-effort: a sample MAY be lost or arrive out of order, and delivery is not acknowledged. The SPATIAL_QUERY/SPATIAL_SNAPSHOT exchange is therefore the authoritative mechanism for a peer's current spatial state; a receiver MUST NOT treat the mere absence of a stream sample as a state change, and a peer that needs a coherent current view MUST obtain it by query rather than by assuming it observed every stream frame — exactly as NPAMP-DISC treats an announcement as non-authoritative relative to a query.

6.4 Association scoping¶

All spatial state is scoped to the association. When the association closes, all frames, transforms, body state, and outstanding queries learned over it are discarded; a peer MUST re-advertise spatial state after a new handshake and MUST NOT carry spatial state from a prior association into a new one.

7. Error model (SPATIAL_ERROR `0x0107`)¶

A failure in the spatial exchange itself is reported as SPATIAL_ERROR, echoing the originating query's corr. Its payload carries the common envelope (§4.2) and:

Field (key)	CBOR type	Meaning
`code` (3)	Unsigned int	One of the codes below.
`reason` (4)	Text string	Advisory human-readable detail (OPTIONAL). MUST NOT be relied on for control flow.

Code	Name	Meaning
1	MalformedPayload	The payload is not valid deterministic CBOR, omits a required field, uses a wrong CBOR major type, carries an unrecognized negative key, or fails the occupancy cell-length check (§4, §5.5).
2	KindMismatch	The payload's `frame_kind` contradicts the frame-header Frame Type (§4.2).
3	UnknownFrame	A query references a `coord_frame` or `child_frame` for which no live FRAME_DEF is held (§5.1, §5.2).
4	FrameTreeConflict	A FRAME_DEF would give a frame a second live parent or would close a cycle (§5.1).
5	FilterUnsupported	A SPATIAL_QUERY carries a filter field the responder does not implement; the responder MUST NOT silently return an over-broad snapshot (§5.6).
6	StaleCursor	A pagination `cursor` the responder no longer recognizes (§5.7).
7	NotAdvertised	The Spatial channel was not advertised for this association, or Spatial is disabled by local policy.
8	ProfileTooLow	The Spatial channel requires the High profile or higher and the negotiated profile is below High (§2).

A responder MUST NOT report a complete true SPATIAL_SNAPSHOT for a set it could not fully and faithfully represent; such a query MUST yield either a paginated snapshot (§5.7) or a SPATIAL_ERROR. An over-broad snapshot returned because an unsupported filter was ignored is a conformance violation (§8): it misleads the requester into acting on state that does not satisfy the constraint it asked for.

8. Conformance¶

An implementation conforms to NPAMP-SPATIAL if and only if, on the Spatial channel 0x0013, it:

Enables the Spatial channel only at the High profile or higher, never at the Standard profile, and drops (or reports ProfileTooLow) Spatial frames arriving under a below-High negotiated profile; and does not deliver frames on a Spatial channel the peer has not advertised during the handshake, dropping such frames (§2);
Uses only the Spatial application frame types defined in §3, all within the channel application band at or above 0x0100, preserves the core meaning of the reserved all-channel frame types (0x0001–0x000A), and defines no Spatial application semantics in the future-core band (0x000B–0x002F) or the companion-extension band (0x0030–0x00FF) (§3);
Encodes every Spatial body as a deterministic-CBOR map (§4.1), rejects a malformed or kind-mismatched payload with the corresponding SPATIAL_ERROR, ignores an unrecognized non-negative key, and rejects an unrecognized negative key (§4);
Applies REP-103 geometry exactly — right-handed frames, body axes x-forward/y-left/ z-up (ENU for geographic frames), unit-quaternion (x, y, z, w) orientation, fixed-axis (X, Y, Z) angular velocity, SI units, and a row-major 6×6 covariance ordered (x, y, z, rotX, rotY, rotZ) — and treats an absent covariance as unknown, not zero (§5);
Maintains a REP-105 single-parent acyclic frame tree — replacing a FRAME_DEF only on a strictly greater epoch, and rejecting a second-parent or cyclic edge with FrameTreeConflict (§5.1, §6.2);
Applies newest-stamp-wins for POSE_UPDATE and STATE_DELTA, ignoring a sample whose stamp is less than or equal to the last applied one and a FRAME_DEF whose epoch does not advance (§6.2);
Enforces correlation per §4.2 and §6.1 — a unique corr on SPATIAL_QUERY, a verbatim echo on SPATIAL_SNAPSHOT and SPATIAL_ERROR, replies matched by corr rather than by frame sequence number, and no corr and no reply on the one-way frames 0x0100– 0x0104 (§6.1);
Never reports a complete true snapshot for a set it could not fully represent (paginating or replying SPATIAL_ERROR instead), applies each present query filter conjunctively, replies FilterUnsupported rather than returning an over-broad snapshot for an unsupported filter, and treats a stream sample as non-authoritative relative to a query (§5.6, §6.3, §7);
Carries no Spatial state across associations and re-advertises after a new handshake (§6.4); and
Adds no cryptographic behavior of its own, treating the crypto suite and operational internals bound to the High or Sovereign profile as governed by the core specification's profile negotiation, out of scope for this application interface (§1.2, §2).

No machine-gradable conformance vectors exist for the Spatial channel yet: a claim of conformance to this document is therefore specification-audited and MUST NOT be represented as corpus-verified. A conformance test suite SHOULD assert each clause above with a recorded exchange on the Spatial channel: a four-frame FRAME_DEF chain (earth → map → odom → base_link) accepted as a tree; a FRAME_DEF that introduces a second parent and one that closes a cycle, each rejected with FrameTreeConflict; a TRANSFORM carrying a quaternion and a 36-element row-major covariance decoded to the expected (x, y, z, rotX, rotY, rotZ) matrix as a byte-exact deterministic-CBOR vector; a POSE_UPDATE stream in which a stamp-ascending sample is applied and a stamp-regressing replay is ignored; an OCCUPANCY_UPDATE under encoding 0 whose cells length is checked against width × height (with a wrong-length payload rejected MalformedPayload) and under encoding 1 decoded to the same grid; a correlated SPATIAL_QUERY/SPATIAL_SNAPSHOT exchange in which a reply bearing a different corr is left unmatched; a paginated snapshot across at least two SPATIAL_SNAPSHOT frames followed by a StaleCursor rejection of an expired cursor; each SPATIAL_ERROR code provoked by the corresponding malformed or unsupported input; a non-negative unknown key ignored while a negative unknown key is rejected; and a Spatial frame under a below-High negotiated profile rejected ProfileTooLow or dropped.