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breadth-20: Token-stream broadcast

Agent report: partial Review pending

Session: completed

docs/spec-dataflow-part-1-streaming.md, lines 26–32

## 1. Token Stream Model A dataflow SSA value denotes an ordered token stream. A token may carry ordinary data, such as an integer, floating point value, vector, or `none`, or it may represent a control event. Multiple SSA uses of the same stream are token broadcast: each use observes the same ordered token sequence.

Execution provenance

The original pilot recorded the compiler hash and checkout revision separately; its binary build revision was not verified. Coverage follow-ups use separately identified rebuilt binaries. Original simulator binary hashes were not retained.

Original standalone-test agent report

This is exploratory evidence, not an accepted production-format PBT.

Ordering and broadcast for integer-payload and i1 control-event token streams are tested end-to-end on the real simulator; floating-point, vector and `none` token payloads and non-stream producers are untested.

Reported numeric verdicts

not measured

Tested obligations

• O1 ordered stream: observations compared as ordered sequences (elementwise, length-sensitive), integer and i1 payloads
• O2 broadcast, direct uses: 2-4 SSA uses of the same dataflow.stream %iv all observe the single-use reference sequence
• O2 broadcast, consumer uses: arith.addi/arith.muli consumers observe the full ordered sequence (elementwise f(iv))
• O2 broadcast for control-event tokens: the i1 %phase stream is unchanged under fan-out
• O2 no-starvation corollary: fan-out must not turn a completing execution into a non-completing one

Untested obligations

• O3 token payload kinds: floating-point, vector and `none` tokens are not broadcast-tested (only iN data tokens and i1 control events)
• Broadcast for streams produced by ops other than dataflow.stream (carry/invariant/gate/channel endpoints)
• Broadcast across dataflow.graph.launch / thread-level channels
• Multi-invocation (--invocations > 1) concatenated activations

Format

Reproduction

Measured subject code coverage

blocked · The pinned subject target cannot be rebuilt with the available Clang 21 or Clang 24 / libstdc++13 toolchains: CgraClosedWaitSetDiagnostic has an implicitly deleted std::variant default constructor. Both simulator and pre-mapping targets depend on this code. No subject source was changed; original uninstrumented runs remain available, with their build revision unverified.

Coverage-preserving minimized cases: not measured

Published evidence

1 artifact(s) omitted because each exceeded the 16 MiB publication limit.