- 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 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 and guarded `.lco` companion 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.
