The previous section settled the algorithm and the bound proof; this makes the
build turnkey rather than exploratory. It is the full scope of the reverted RTN
attempt (whose group sharing was correct) with the explicit return stack replaced
by the graph-structured stack:
- Step 1: a group-definition identity (`Group.definitionID`, stamped from the
existing `GroupParticleMemoKey` in `XSDParserParticles`), FP-neutral on its own.
- Step 2: a `ContentRTNBuilder` alongside the trusted inlining `ContentNFABuilder`,
compiling each definition once via `call`/`return` epsilon edges, counters still
per-configuration and reset on entry so a shared fragment does not alias.
- Step 3: the GSS simulation: a node `(returnState, parents-set)` interned per
`(returnState, inputPosition)`, configuration `(state, counters, gssNode)`, with
call interning and pop fan-out, deduplicated on the configuration key.
- Step 4: the differential gate against the inlining oracle (XSTS + a
nullable-nested-group fuzz, verdict AND matched-particle equal), then the switch
and a perf assertion on GSS/configuration COUNTS (not a wall-clock timeout, the
reverted attempt's lesson).
Each step is its own PR; steps 1-2 keep the oracle authoritative, step 4 is the
only behaviour change and is gated to equivalence before it lands. Design only.
Mihaela Mihaljevic
116b260149