- The active static parser head is now the `engine_types` semantics frontier.
The repo now has structural inspectors for `.car`, `.lco`, `.cgo`, and `.cct`, but the binary side is still only partially semantic: the checked 1.05 corpus grounds `.car` fixed strings at `0x0c / 0x48 / 0x84` plus a second fixed stem slot at `0xa2` and a side-view resource name at `0xc0`, while `.lco` carries a stable primary stem at `0x04` and only conditional companion/body slots at `0x0c` and `0x12` when the leading stem slot is padded.
The checked 1.05 corpus now also splits `.car` auxiliary stems into `126` direct matches, `14` role-neutral roots, and only `5` truly distinct cases, while `.cgo` collapses into five stable scalar ladders instead of arbitrary floats.
The early `.lco` lane block is now partially partitioned too: only offsets `0x20`, `0x34`, `0x38`, `0x3c`, `0x44`, `0x48`, and `0x54` behave like low-cardinality buckets, while the other early lanes still look high-variance.
The next honest static work is to keep promoting those fixed lanes into stable parser fields, explain the five remaining distinct auxiliary-stem cases, and decide how far the `.cgo` ladders plus the low-cardinality `.lco` lanes can be grounded without overclaiming semantics.
Preserved checked format inventory detail now lives in [RT3 format inventory](rehost-queue/format-inventory-2026-04-21.md).
## Preserved External And Dynamic Blockers
- The locomotives-page tail remains preserved as an external-corpus blocker.
Static repo-local work on this head is now exhausted: the local `29`-save `.gms + .gmx` census proves the stable prefix through `58`, proves the same two scenario-dependent `59+` tail families, and still finds no `Class QJ` placement plus no descriptor carriers in `452` or `457..502`. The next honest non-hook step requires a broader save corpus; the next non-static step requires dynamic tracing.
Preserved checked blocker detail now lives in [Locomotive descriptor tails](rehost-queue/locomotive-descriptor-tails-2026-04-21.md).
- The periodic-company control-lane head remains preserved as a dynamic blocker around the ordinary loaded runtime-effect strip `0x00444d92 -> 0x00432f40(kind 8) -> 0x004323a0 -> 0x00431b20`.
Static progress on this head now appears genuinely blocked: the whole-binary `[...+0x7ef]` reference census still collapses to the grounded writer set plus the already-known compare and copy helpers, so the next honest step likely requires hook-side or runtime tracing between reload `0x00433130` and the world-entry kind-`8` sweep at `0x00444d92`.
- The Tier-2 building head remains preserved as a dynamic blocker around the seed/projection seam into `0x00412d70`.
The stock decode chain, the bare-name remap callback, the rebank-or-clone owner, and the earlier suspected mid-range replay strip are all now grounded, so the next honest step likely requires runtime tracing of which source rows actually enter the live bank-qualified seed set.
