Function heap_to_json_value 

pub fn heap_to_json_value(hv: &HeapValue) -> Result<JsonValue, String>

Walk a HeapValue tree and produce a JsonValue.

Universal intermediate per the N7 ε disposition (docs/defections.md, 2026-05-07). Format-specific encoders take &JsonValue (NOT &HeapValue) and produce per-format bytes/string. Mirrors json.rs’s parse-side serde_json_to_json_value (stdlib/json.rs:172-196) in reverse.

Recursion lives at the JsonValue layer (Array/Object children); the ConcreteReturn leaf-only invariant is preserved.

Variant classification (REFINEMENT-1A + REFINEMENT-1B-ITEM-A)

Mechanical-yes (5): String, BigInt, Char, TypedArray, HashMap

• TypedObject schema-aware (1) — produce a JsonValue directly or recurse.

Categorically-non-data Reject (5): Future, IoHandle, NativeView, ClosureRaw, TaskGroup — Err("cannot serialize: <variant>") permanently. These hold runtime resources; no serialization policy can convert them to wire format.

Architectural-choice deferred (7): Decimal, DataTable, Content, Temporal, TableView, Instant, NativeScalar — first-landing Err(<policy not yet decided>). Each represents a user-visible behavioral commitment requiring explicit decision per consumer demand.

V3-S5 ckpt-5-prime (2026-05-15): the TypedArrayData inner-dispatch description below previously named the 13-arm typed_array_to_json_value helper. That helper + the HeapValue::TypedArray(ta) outer arm here are RETIRED in lockstep with the deleted HeapValue::TypedArray variant (ckpt-4) + deleted TypedArrayData inner enum (ckpt-1). The v2-raw *mut TypedArray<T> JSON-serialisation path lands at the ckpt-5-prime²

• ckpt-6 producer/consumer storage-shape migration (per W12 audit §3.6 — no *mut TypedArray<T> value ever reaches heap_to_json_value post-V3-S5 ckpt-5: the JSON projection happens at the marshal layer before the value becomes a HeapValue). Refusal #1 binding.