pyvm: split op handlers into ops_core/ops_box/ops_ctrl; add ops_flow + intrinsic; delegate vm.py without behavior change

net-plugin: modularize constants (consts.rs) and sockets (sockets.rs); remove legacy commented socket code; fix unused imports
mir: move instruction unit tests to tests/mir_instruction_unit.rs (file lean-up); no semantic changes
runner/pyvm: ensure using pre-strip; misc docs updates

Build: cargo build ok; legacy cfg warnings remain as before

docs/proposals/scope-reuse.md

@@ -0,0 +1,75 @@
+# Scope Reuse Blocks (MVP Proposal)
+
+Status: design-only during freeze (no implementation)
+
+Summary
+- Give short, reusable logic a name within the current scope without promoting it to a top-level function.
+- Keep the core small: block body + postfix header sugar; desugar to local function + normal calls.
+- Zero runtime cost: lowers to let/if/call/ret only (no new instructions/closures).
+
+Syntax (postfix header; Nyash style)
+- Block form (multi-statement):
+  ```nyash
+  { /* BODY */ } scope name(arglist?) (-> Ret)?
+  // call within the same scope
+  name(args)
+  ```
+- Expression form (one-liner):
+  ```nyash
+  => EXPR  scope name(arglist?) (-> Ret)?
+  ```
+
+Semantics
+- Visibility: `name` is local to the defining scope; not exported.
+- Capture: by reference by default. Mutating captured vars requires explicit `mut` on those bindings.
+- Recursion: disallowed in MVP (can be lifted later).
+- Errors/exits: same as regular functions (return/cleanup/catch apply at the function boundary).
+
+Lowering (desugaring)
+- Transform into a local function plus a local binding for convenience calls.
+  ```nyash
+  // { BODY } scope check(a:Int)->Str
+  // ↓ (conceptual)
+  let __cap_me = me; let __cap_locals = { /* needed refs */ };
+  method __scope_check__(a:Int)->Str {
+    return BODY
+  }
+  let check = (x) => __scope_check__(x)
+  ```
+- Captures are passed via hidden arguments or an environment box; no new VM opcodes.
+
+Examples
+```nyash
+{ if x % 2 == 0 { return "even" } return "odd" } scope parity(x:Int)->StringBox
+
+for i in range(0,10) {
+  print(parity(i))
+}
+```
+
+Safety rules (MVP)
+- Capture: read-only by default; writes allowed only when the captured binding is declared `mut`.
+- Name uniqueness: `scope name` must be unique within the scope.
+- No cross-scope escape: values may be returned but the function reference itself is not exported.
+
+Observability & Tooling
+- Add trace toggles (design only):
+  - `NYASH_SCOPE_TRACE=1|json` to emit enter/exit and capture lists as JSONL.
+  - Example: `{ "ev":"enter","sid":42,"caps":["me","cfg","mut total"] }`.
+- Lints (design only):
+  - Single-use scope → suggest inline.
+  - Excess captures → suggest narrowing.
+
+Interactions
+- Works with guard/with/await sugars (it’s just a call).
+- Compatible with ASI and postfix aesthetics; no new top-level keywords beyond `scope` suffix.
+
+Tests (syntax-only smokes; design)
+- scope_basic: called twice → same result.
+- scope_capture_read: reads `me/foo`.
+- scope_capture_mut: mutation only allowed when `mut` is present.
+- scope_with_catch_cleanup: postfix catch/cleanup applied at local-function boundary.
+
+Freeze note
+- This is documentation and design intent only. Implementation is deferred until after the freeze.
+