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jolt/docs/seed-overlay-registry.md
Yogthos 45876998ad Docs: Chez-only, drop the Janet-era references and obsolete migration notes 
Bring the docs in line with the actual implementation now that Chez is the sole
substrate.

Deleted the migration/spike/handoff artifacts that only documented the Janet
era or the port effort: the port plan, phase-0 and foundational-runtime spike
writeups (+ the stray root-level copy), the self-hosting design notes, the
architecture-refactor plan, and spike/chez/RESULTS.md.

Rewrote the current reference docs against the Chez facts: building-and-deps and
tools-deps (no jpm/build step — bin/joltc off the checked-in seed, deps via
jolt.deps into ~/.jolt/gitlibs), libraries (SQLite is built-in jdbc.core over
libsqlite3, not a Janet driver), the conformance/spec test-flow docs (the Chez
corpus runner + certify, no .janet harnesses), and the transient / type-hint /
seed-overlay design notes (Chez representations: mutable transients, flat
copy-on-write vectors, HAMT maps, the seed/overlay twin). Fixed the README
collections line (vectors aren't 32-way tries) and added the ffi/transient gate
targets. rfc 0001's numerics open-question is resolved (the Scheme tower).

Renamed the built-in HTTP adapter to jolt.http.server only (dropped the
ring-janet.adapter alias — a Janet-era name).
2026-06-22 09:05:35 -04:00

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Seed ↔ Overlay Registry

Jolt is Clojure on Chez Scheme. clojure.core is built from two tiers that both define clojure.core-facing vars, and for a handful of names both tiers carry a definition. This document records how the two tiers relate and which copy is authoritative.

The two tiers

  • Native shims (host/chez/natives-*.ss) bind a set of clojure.core vars directly to Scheme runtime values via def-var! — collection constructors, seq fns, numeric/string ops, and so on. These cover names the overlay assumes exist as bare clojure.core vars but does not define itself.
  • The Clojure overlay (jolt-core/clojure/core/NN-*.clj) defines the rest of clojure.core in dependency-ordered tiers, loaded in order: 00-syntax, 00-kernel, 10-seq, 20-coll, 25-sorted, 30-macros, 40-lazy, 50-io.

The overlay loads after the native shims. When an overlay tier (defn X …) for a name a native shim already bound, the overlay def shadows the native binding — user code sees the overlay copy. The native binding then survives only if some other native/runtime code still calls the Scheme value directly.

So a name's home is determined by two facts:

  1. is it bound by a native shim? (the Scheme value is reachable from the runtime)
  2. does an overlay tier (defn X …)? (the overlay copy is what user code sees)

The compiled seed

clojure.core is compiled ahead of time into the checked-in seed (host/chez/seed/{prelude,image}.ss) as Scheme def-var! forms. The seed's source twin is the overlay (jolt-core/clojure/core/*.clj plus the stdlib namespaces under src/jolt/clojure/); host/chez/emit-image.ss re-emits the prelude from those sources on Chez. The build is a byte-fixpoint: rebuilding from an up-to-date seed reproduces it exactly.

Consistency guard

There is no separate drift-check test for the registry. The self-hosting fixpoint is the guard: after changing a seed source (a core tier, the compiler namespaces, the host contract, the reader, or emit-image.ss) you must re-mint the seed (make remint), and make selfhost fails if the checked-in seed and its sources have drifted. So if the overlay's shadowing relationship changes, the re-minted prelude changes with it, and the fixpoint check keeps source and seed in agreement.