Add `PrimitiveBuilder::bind(slot, value)`: bind a declared param to a structural
constant, removed from param_space entirely rather than pinned in the injected
vector. This closes the gap #55 names — param-bearing nodes (Sma/Exposure/LinComb)
had no constant path, only the no-sweep-mode SimBroker precedent. The motivating
case is "SMA2-entry": the 2 is bound to the two-candle construction, so sweeping
it would enumerate deformed strategies as valid family members.
Approach (Option B, builder-level — the originally-planned direction): bind shrinks
the builder's declared param surface (schema.params) and wraps its build closure to
re-splice the captured constant at its original positional slot. The construction
layer (collect_params / lower_items / param_space / compile_with_params) is
byte-unchanged: both dock sites already key off builder.params(), so the shrink
propagates for free. Addressing is by param name (the by-name authoring address
space, C23/0032); the compilat stays wired by raw index — names never reach it.
bind enforces "exactly one open param matches" itself (collect-all-then-reject,
panic on zero / on duplicate), mirroring the resolve binder's posture, because a
node's own schema.params is not covered by check_param_namespace_injective. Chained
binds reconstruct the correct positional vector because each layer computes its
slot index relative to the param list it sees (no global position table).
Considered and rejected: a per-node builder_const(N) constructor (explodes
combinatorially over which subset is constant, not dynamic); a ParamBinding overlay
struct on Composite (would need new bookkeeping the builder-level form avoids).
Verified: cargo build/clippy/test --workspace all green; new tests cover slot
removal, positional reconstruction (chained + partial, via eval), the three panic
paths, and the composite param_space projection; blueprint.rs construction layer
confirmed byte-unchanged.
Deferred (out of scope, follow-up issue): exporting a named frozen strategy as a
blueprint-as-values collection — the issue's third fork, needs its own brainstorm.
closes#55
Brummel
7d587d0c4e