cap truncates a deep type's field VALUES to :any so the inter-procedural
fixpoint stays finite, but it rebuilt the struct via mk-struct and dropped the
record :type tag along the way. The tag is identity — independent of field
depth — so a record stored in a deep container (a Sphere in a world vector, a
material on a hit) degraded to a plain struct, and devirtualization (jolt-41m)
and record? folding silently stopped firing on it.
Preserve :type alongside :shape when capping. Verified: a protocol call on a
record read out of a vector now devirtualizes (the call node gets :devirt-type,
which needs the receiver's record type). Sound — the tag stays accurate; only
field values below the depth cap are truncated.
No measurable wall-clock change on its own (jolt's protocol dispatch is already
cheap), but it restores the record fast path / devirt / record?-folding on
records-in-containers, and unblocks downstream work that keys off record types.
Co-authored-by: Yogthos <yogthos@gmail.com>
ae593b0f66