CC Window Aligner: System Glossary
Version: 0.1.0
Status: DRAFT
Last Updated: 2025-12-27
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Core Terms
MotionWindow
| Aspect | Definition |
|---|
| What it is | A fixed-length segment of aligned, fused motion data with deterministic semantics. The atomic unit of motion truth consumed by downstream modules. |
| What it is NOT | Raw sensor data. A prediction. A variable-length sequence. An approximation. |
| Layer | Runtime (output of Aligner, input to cc-anticipation) |
| Stability | FROZEN after v0.1.0 lock. Schema changes require major version bump. |
SkeletonFrame
| Aspect | Definition |
|---|
| What it is | A single frame of fused skeletal pose data at a canonical timestamp. Contains joint positions, orientations, and provenance metadata. |
| What it is NOT | Raw mocopi data. Device-specific coordinates. Interpolated without marking. |
| Layer | Runtime (internal to MotionWindow) |
| Stability | FROZEN after v0.1.0 lock. |
CanonicalTime
| Aspect | Definition |
|---|
| What it is | A monotonic time axis shared across all devices in a session. Defined relative to a reference clock (host or designated transmitter). |
| What it is NOT | Wall-clock time. Device-local timestamps. UTC. |
| Layer | Conceptual / Runtime |
| Stability | Definition stable. Implementation may vary per session. |
DeviceMask
| Aspect | Definition |
|---|
| What it is | A bitmask indicating which devices contributed to a MotionWindow or SkeletonFrame. |
| What it is NOT | A quality indicator. A list of all available devices. |
| Layer | Runtime |
| Stability | Bit positions are FROZEN per device type. |
Provenance
| Aspect | Definition |
|---|
| What it is | Metadata indicating which device(s) contributed to each degree of freedom in a SkeletonFrame, including interpolation flags. |
| What it is NOT | A confidence score. A reliability metric. |
| Layer | Runtime |
| Stability | Schema stable after lock. |
Coverage
| Aspect | Definition |
|---|
| What it is | A scalar [0, 1] indicating the fraction of frames in a MotionWindow that have valid (non-interpolated) data from authoritative sources. |
| What it is NOT | A quality score. A recommendation. |
| Layer | Runtime |
| Stability | Computation formula FROZEN after lock. |
Interpolation Policy
| Aspect | Definition |
|---|
| What it is | A versioned, frozen specification of how to estimate values at canonical frame times when raw samples are not available at those exact times. |
| What it is NOT | A tunable parameter. A runtime choice. |
| Layer | Architectural (frozen) |
| Stability | IMMUTABLE per policy version. Changes require new policy version. |
Watermark
| Aspect | Definition |
|---|
| What it is | A canonical timestamp beyond which no earlier packets are expected. Used to determine when frames can be safely emitted. |
| What it is NOT | A deadline. A timeout. |
| Layer | Runtime |
| Stability | Algorithm stable, parameters configurable. |
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Stream Terms
RawPacket
| Aspect | Definition |
|---|
| What it is | An unprocessed data unit from a sensor device, with device-local timestamp and device-specific payload. |
| What it is NOT | Aligned data. Canonical-time data. Interpreted data. |
| Layer | Runtime (input) |
| Stability | Format varies by device type. |
DeviceStream
| Aspect | Definition |
|---|
| What it is | A sequence of RawPackets from a single device, with estimated clock mapping to canonical time. |
| What it is NOT | A fused stream. A canonical-rate stream. |
| Layer | Runtime (internal) |
| Stability | Internal representation. |
ClockMapping
| Aspect | Definition |
|---|
| What it is | An affine transformation (offset + drift) mapping device timestamps to canonical time: `t_canonical = a * t_device + b`. |
| What it is NOT | A constant offset. A prediction. |
| Layer | Runtime (internal) |
| Stability | Algorithm stable. |
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Coordinate Terms
BodyFrame
| Aspect | Definition |
|---|
| What it is | The canonical coordinate system for skeletal pose. Right-handed, Z-up, origin at pelvis, X forward. |
| What it is NOT | Device coordinates. World coordinates. Camera coordinates. |
| Layer | Architectural (frozen) |
| Stability | IMMUTABLE. |
BoneIndex
| Aspect | Definition |
|---|
| What it is | An integer index [0, 26] identifying a bone in the canonical 27-bone skeleton. |
| What it is NOT | A mocopi-specific index. A device-specific identifier. |
| Layer | Architectural (frozen) |
| Stability | Mapping FROZEN after lock. |
MountingOffset
| Aspect | Definition |
|---|
| What it is | A known spatial offset from a device's sensor frame to the corresponding skeletal attachment point (e.g., phone in pocket to pelvis). |
| What it is NOT | A calibration result. A learned parameter. |
| Layer | Configuration (per device type) |
| Stability | Defaults FROZEN. Per-session overrides allowed. |
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Mode Terms
StrictMode
| Aspect | Definition |
|---|
| What it is | Aligner operating mode prioritizing determinism and replay stability over latency. Waits for watermark before emitting. |
| What it is NOT | A quality setting. A preference. |
| Layer | Configuration |
| Stability | Behavior FROZEN per version. |
LowLatencyMode
| Aspect | Definition |
|---|
| What it is | Aligner operating mode prioritizing responsiveness for interactive use. May emit with incomplete data, marking uncertainty. |
| What it is NOT | Best-effort. Lossy. Non-deterministic (still deterministic given same inputs). |
| Layer | Configuration |
| Stability | Behavior FROZEN per version. |
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Pipeline Terms
Stage
| Aspect | Definition |
|---|
| What it is | A discrete processing step in the aligner pipeline. There are exactly 5 stages. |
| What it is NOT | A module. A thread. An optional component. |
| Layer | Architectural |
| Stability | Stage count and order FROZEN. |
Stage 1: TimeNormalization
| Aspect | Definition |
|---|
| What it is | Maps all raw packet timestamps to canonical time using per-stream clock mappings. |
Stage 2: Resampling
| Aspect | Definition |
|---|
| What it is | Interpolates each stream onto the canonical frame lattice (e.g., 50 Hz). |
Stage 3: CoordinateUnification
| Aspect | Definition |
|---|
| What it is | Transforms all streams into the common BodyFrame with consistent skeleton conventions. |
Stage 4: Fusion
| Aspect | Definition |
|---|
| What it is | Combines multi-device data into a single SkeletonFrame per canonical timestamp, with provenance. |
Stage 5: Windowing
| Aspect | Definition |
|---|
| What it is | Slices the fused stream into fixed-length MotionWindows with overlap and metadata. |
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Validation Terms
Discontinuity
| Aspect | Definition |
|---|
| What it is | A detected jump in pose or orientation that exceeds physical plausibility thresholds. |
| What it is NOT | Missing data. Noise. Normal motion. |
| Layer | Runtime (validation) |
| Stability | Thresholds configurable, detection algorithm FROZEN. |
CausalityTrace
| Aspect | Definition |
|---|
| What it is | A log entry connecting a downstream output (e.g., audio chunk) to the specific MotionWindow and frames that conditioned it. |
| What it is NOT | A performance metric. A debug log. |
| Layer | Audit / Runtime |
| Stability | Schema stable. |
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Device Types
| Device | DeviceMask Bit | Primary Contribution |
|---|
| Mocopi | 0x01 | Full-body skeletal pose (27 bones) |
| iPhone (pocket) | 0x02 | Hip translation energy, step detection |
| Apple Watch (wrist) | 0x04 | Wrist cadence, heart rate |
| AirPods (head) | 0x08 | Head orientation, yaw/pitch |
| Depth Camera | 0x10 | (Future) Full-body refinement |
| Reserved | 0x20-0x80 | Future device types |
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Invariant Terms
See [INVARIANTS.md](./INVARIANTS.md) for the full invariants ledger.
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Document ID: CC-WA-GLOSSARY-001
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