ocaml: phase 4 open / include (+5 tests, 220 total)

Parser: open Path and include Path top-level decls; Path is Ctor (.Ctor)*.
Eval resolves via ocaml-resolve-module-path (same :con-as-module-lookup
escape hatch used by :field). open extends the env with the module's
bindings; include also merges into the surrounding module's exports
(when inside a struct...end).

Path resolver lets M.Sub.x work for nested modules. Phase 4 LOC ~165.

plans/ocaml-on-sx.md

@@ -186,8 +186,11 @@ SX CEK evaluator (both JS and OCaml hosts)
 - [ ] `module M : S = struct ... end` — coercive sealing (runtime: pass-through).
 - [ ] `functor (M : S) -> struct ... end` → SX `(fn (M) ...)`.
 - [ ] `module F = Functor(Base)` — functor application.
-- [ ] `open M` — merge M's dict into current env (`env-merge`).
-- [ ] `include M` — same as open at structure level.
+- [x] `open M` — merge M's dict into current env (via
+      `ocaml-env-merge-dict`). Module path `M.Sub` resolves via
+      `ocaml-resolve-module-path`.
+- [x] `include M` — at top level same as `open`; inside a module also
+      copies M's bindings into the surrounding module's exports.
 - [x] `M.name` — dict get via field access.
 - [ ] First-class modules (pack/unpack) — deferred to Phase 5.
 - [ ] Standard module hierarchy: `List`, `Option`, `Result`, `String`, `Char`,
@@ -322,6 +325,15 @@ the "mother tongue" closure: OCaml → SX → OCaml. This means:
 
 _Newest first._
 
+- 2026-05-08 Phase 4 — `open M` / `include M` (+5 tests, 220 total).
+  Parser: top-level `open Path` / `include Path` decls; path is `Ctor (.
+  Ctor)*`. Eval resolves the path via `ocaml-resolve-module-path` (the
+  same `:con`-as-module-lookup escape hatch used for `:field`); merges
+  the dict bindings into the current env via `ocaml-env-merge-dict`.
+  `include` inside a module also adds the bindings to the module's
+  resulting dict, so `module Sphere = struct include Math let area r =
+  ... end` exposes both Math's `pi` and Sphere's `area`. Phase 4 LOC
+  cumulative: ~165.
 - 2026-05-08 Phase 4 — modules + field access (+11 tests, 215 total). Parser:
   `module M = struct DECLS end` decl in `ocaml-parse-program`. Body parsed
   by sub-tokenising the source between `struct` and the matching `end`,