Large / variable-payload slice channel

A second delivery mechanism in taktora-connector-transport-iox, additive to the fixed-N ConnectorEnvelope<N> POD envelope: a variable-length, zero-copy channel for bulk one-shot payloads whose size is not known at compile time. It exists so higher-layer connectors (first consumer: taktora-connector-j1939 ETP, ETP over the slice channel,... (REQ_0894)) can move large messages — firmware blobs, camera frames — without inlining a worst-case buffer into every sample. This cluster :satisfies: Connector framework (FEAT_0030).

Feature: Large / variable-payload slice channel FEAT_0097

status: draft satisfies: FEAT_0030 is satisfied by: REQ_0900, REQ_0885, REQ_0886, REQ_0887, REQ_0888, REQ_0889

A variable-length channel pair backed by an iceoryx2 slice ([u8]) publish-subscribe service. Where Envelope transport (FEAT_0031)’s ConnectorEnvelope<N> pins payload capacity at compile time, this channel sizes each sample to the message at send time and lets the shared-memory segment grow on demand, capped by a configurable ceiling so the bounded-allocation posture of Bounded global allocator (FEAT_0040) still holds. It is an opt-in bulk path: connectors with statically-known payload sizes keep using the POD envelope.

Requirement: Slice-typed variable-length channel REQ_0885

status: implemented github: 121 satisfies: FEAT_0097 is refined by: IMPL_0091 is implemented by: BB_0097 is verified by: TEST_0884 links outgoing: BB_0097, TEST_0884

taktora-connector-transport-iox shall provide a variable-length channel pair (SliceChannelWriter / SliceChannelReader) backed by an iceoryx2 slice ([u8]) publish-subscribe service that delivers exactly one message per sample, zero-copy.

Requirement: Loans sized at send time REQ_0886

status: implemented github: 121 satisfies: FEAT_0097 is refined by: IMPL_0091 is implemented by: BB_0097 is verified by: TEST_0884 links outgoing: BB_0097, TEST_0884

The slice channel shall size each published sample to the message length at send time via iceoryx2 loan_slice / loan_slice_uninit, rather than a compile-time N const generic.

Requirement: Segment grows by PowerOfTwo REQ_0887

status: implemented github: 121 satisfies: FEAT_0097 is refined by: IMPL_0091 is implemented by: BB_0097 is verified by: TEST_0885 links outgoing: BB_0097, TEST_0885

The slice channel shall start from a configurable initial_max_slice_len and grow its shared-memory data segment using AllocationStrategy::PowerOfTwo when a message larger than the current segment is loaned.

Requirement: Growth bounded by a configurable ceiling REQ_0888

status: implemented github: 121 satisfies: FEAT_0097 is refined by: IMPL_0091 is implemented by: BB_0097 is verified by: TEST_0885 links outgoing: BB_0097, TEST_0885

The slice channel shall reject — with a bounded-capacity ConnectorError — any loan whose length exceeds a configurable max_payload_bytes ceiling, so segment growth stays bounded and auditable rather than open-ended (upholds the bounded-allocation posture of Bounded global allocator (FEAT_0040)).

Requirement: Single-publisher topology and metadata parity REQ_0889

status: implemented github: 121 satisfies: FEAT_0097 is refined by: IMPL_0091 is implemented by: BB_0097 is verified by: TEST_0884 links outgoing: BB_0097, TEST_0884

The slice channel shall preserve the framework’s single-publisher iceoryx2 topology and shall carry the same sequence_number and timestamp_ns metadata semantics that Sequence number monotonical... (REQ_0202) and Timestamp recorded at send (REQ_0203) define for ConnectorEnvelope, exposed through an iceoryx2 user-header rather than an inline POD struct.

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