Julep determinism contract: register the raw def, keep captures clean

The rules, plainly: do not register wrappers, closures, or lambdas. Register the raw def. Captured constants must be canonical JSON and small. Runtime handle captures must come from the enclosing graph (no foreign-scope captures). Secret-shaped config is banned from captures and static args; credentials belong in environment-backed tools or run principals, never in the frozen flow artifact. Healthy means no UNKNOWN_PURE, ARR_ARGS_NOT_JSON, or ARR_ARGS_SECRET diagnostics. Two more naming rules that bite: branch arms receive the branch subject by name, so the remaining arm parameter must match the subject handle label and every other enclosing value must be supplied as a keyword capture. each(...) bodies differ: the item parameter is positional, while enclosing handles and constants are captures. Names are single-assignment graph fields derived from whole-function AST source when available; use name= as the explicit escape hatch (REPL and exec contexts fall back to deterministic generated names). Also know how constant kwargs lower: JSON constant kwargs on registered pures become arr static args and run as fn(value, **kwargs); on tools and reasoners they lower to std.bind const-merges into the flowing record before the call.

Context: Official docs (Julep authoring guide, Determinism Contract): every callable used on a Handle must be registered by its raw function source with @tool or @pure. Pure pins are source hashes of the raw function, which is why wrapping breaks things.