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fix: is_parity flag, strict encoding all segments

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Igor Sirotin 2026-04-30 15:19:55 +01:00
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standards/application/segmentation.md
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@ -44,38 +44,43 @@ message SegmentMessageProto {
bytes entire_message_hash = 1;
// Data segment indexing
uint32 index = 2; // zero-based sequence number; valid only if segments_count > 0
uint32 segments_count = 3; // number of data segments
uint32 index = 2; // zero-based sequence number for data segments
uint32 segments_count = 3; // number of data segments (>= 1)
// Segment payload (data or parity shard)
bytes payload = 4;
// Parity segment indexing (used if segments_count == 0)
// Parity segment indexing
uint32 parity_segment_index = 5; // zero-based sequence number for parity segments
uint32 parity_segments_count = 6; // number of parity segments
// Segment type
bool is_parity = 7; // true for parity segments, false (default) for data segments
}
```
**Field descriptions:**
- `entire_message_hash`: A 32-byte Keccak256 hash of the original complete payload, used to identify which segments belong together and verify reconstruction integrity.
- `index`: Zero-based sequence number identifying this data segment's position (0, 1, 2, ..., segments_count - 1).
- `segments_count`: Total number of data segments the original message was split into.
- `index`: Zero-based sequence number identifying this data segment's position (0, 1, 2, ..., segments_count - 1). Set only on data segments.
- `segments_count`: Total number of data segments the original message was split into. Set on every segment (data and parity).
- `payload`: The actual chunk of data or parity information for this segment.
- `parity_segment_index`: Zero-based sequence number for parity segments.
- `parity_segments_count`: Total number of parity segments generated.
- `parity_segment_index`: Zero-based sequence number for parity segments. Set only on parity segments.
- `parity_segments_count`: Total number of parity segments generated. Set on every segment (data and parity) when Reed–Solomon parity is used; `0` (default) otherwise.
- `is_parity`: Explicit segment type marker. `false` (default) for data segments; `true` for parity segments.
A message is either a **data segment** (when `segments_count > 0`) or a **parity segment** (when `segments_count == 0`).
A message is either a **data segment** (when `is_parity == false`) or a **parity segment** (when `is_parity == true`).
### Validation
Receivers **MUST** enforce:
- `entire_message_hash.length == 32`
- **Data segments:**
`segments_count >= 1` **AND** `index < segments_count`
- **Parity segments:**
`segments_count == 0` **AND** `parity_segments_count > 0` **AND** `parity_segment_index < parity_segments_count`
- `segments_count >= 1`
- **Data segments** (`is_parity == false`):
`index < segments_count`
- **Parity segments** (`is_parity == true`):
`parity_segments_count > 0` AND `parity_segment_index < parity_segments_count`
No other combinations are permitted.
A `SegmentMessageProto` with `segments_count == 1` and `index == 0` is a valid single-segment data message: the `payload` field carries the entire original payload (see [Sending](#sending)).
@ -91,9 +96,12 @@ To transmit a payload, the sender:
each of size up to `segmentSize` bytes.
A payload of size ≤ `segmentSize` produces a single data segment (`segments_count == 1`).
- **MAY** use Reed–Solomon erasure coding at the predefined parity rate.
- Encode each segment as a `SegmentMessageProto` with:
- **MUST** encode every segment as a `SegmentMessageProto` with:
- The `entire_message_hash`
- Either data-segment indices (`segments_count`, `index`) or parity-segment indices (`parity_segments_count`, `parity_segment_index`)
- `segments_count` (total number of data segments, always set)
- When Reed–Solomon parity is used, `parity_segments_count` (total number of parity segments, set on every segment)
- For data segments: `is_parity = false`, `index`
- For parity segments: `is_parity = true`, `parity_segment_index`
- The raw payload data
- Send each segment as an individual transport message according to the underlying transport protocol,
preserving application-level metadata (e.g., content topic).