Brummel
5b66de77ac
Forward-fix on c42034b. plan-recon for intrinsic-bodies.1 surfaced
that the original AST representation — FnDef.body / Term::Lam.body
made Option<Term> plus an `intrinsic: bool` flag — has a ~150-site
blast radius across six crates: every body read/construct site breaks
when a mandatory public field goes optional. That blast radius is the
signal (CLAUDE.md design-rationale rule) that the representation was
wrong, not merely expensive.
The Form-A surface (user's chosen Approach 1) and the Local-Reasoning
semantics (Design X marker placement) are UNCHANGED. Only the internal
AST representation changes, which is orchestrator authority over AST
design.
New representation: a single new leaf Term variant, Term::Intrinsic
({ "t": "intrinsic" }), is the body of a compiler-supplied definition.
FnDef.body (Term) and Term::Lam.body (Box<Term>) keep their existing
types. A def is intrinsic iff matches!(body, Term::Intrinsic).
Three structural reasons (not effort):
1. Established pattern. The project adds new constructs as additive
Term variants — Term::New, Term::Loop, Term::Recur, Term::Clone,
Term::ReuseAs all landed this way, documented "strictly additive,
pre-existing fixtures hash bit-identically" in
design/contracts/0002-data-model.md. Term::Intrinsic follows it.
Option A introduced a brand-new pattern (mandatory field → optional)
absent from the schema.
2. Meaning at the right locus. "This body is compiler-supplied" is a
property of the body, not the container. Term::Intrinsic sits at the
body position — fn body, or instance-method lambda body (Design X
local-signature placement preserved exactly).
3. Illegal state unrepresentable. Option A admitted intrinsic:true with
body:Some(...), forcing an intrinsic-with-body reject. Under the
variant a body is either Term::Intrinsic or a real term, never both
— the reject is deleted, the state cannot occur. This is the same
make-illegal-states-unrepresentable discipline as the honesty theme
the milestone exists to serve.
Blast radius collapses from ~150 body-read/construct sites to the
exhaustive match-on-Term arms (canonical/hash/visit + schema_coverage),
which the no-wildcard Term match turns into compile errors until each
gains a Term::Intrinsic case — the project's normal new-variant
discipline.
Sections revised: § Architecture points 1/3/4, § Concrete code shapes
(Implementation shape now shows the leaf variant, not the
Option+flag), § Components, § Data flow, § Error handling (the
intrinsic-with-body row removed), § Testing strategy (the
both-body-and-intrinsic reject test removed; schema_coverage Term::Intrinsic
observation added). The scheme/ail surface examples are byte-unchanged.
Re-ran the brainstorm gates on the revision: Step-7 parse gate green
(both ail blocks exit 0, unchanged); Step-7.5 grounding-check PASS on
the four new load-bearing claims (additive-variant precedent +
contract wording, exhaustive-Term-match mechanism, mono.rs
synthesise_mono_fn destructure unchanged under preserved body type,
Term::Recur as non-reducing-leaf precedent).