fix(code-runtime-python): stop the program's compile from inheriting the module's future annotations

bootstrap.py imports from __future__ import annotations; compile(wrapped) was
inheriting that PEP 563 flag, stringifying the program's type annotations and
changing the semantics of a legal program that reads f.__annotations__ at
runtime. compile(..., dont_inherit=True) stops the leak; a regression test
defines an annotated function and asserts the annotation is the live int class,
verified fail-before by removing dont_inherit (the test turns red).

packages/code-runtime/code-runtime-python/py/bootstrap.py

@@ -1300,7 +1300,11 @@ async def _run(channel: ProtocolChannel) -> None:
         ast.copy_location(wrapper, anchor)
         wrapped = ast.Module(body=[wrapper], type_ignores=[])
         ast.fix_missing_locations(wrapped)
-        code = compile(wrapped, "<model>", "exec")
+        # `dont_inherit=True` stops this module's `from __future__ import
+        # annotations` (line 14) from leaking into the program's compile: PEP 563
+        # would otherwise stringify the program's type annotations, changing the
+        # semantics of a legal program that reads `f.__annotations__` at runtime.
+        code = compile(wrapped, "<model>", "exec", dont_inherit=True)
         exec(code, ns)  # noqa: S102 -- defines __dsh_main__; executing model code is the point
         value = await ns["__dsh_main__"]()
         die_if_cpu_exhausted(cpu_seconds)

packages/code-runtime/code-runtime-python/tests/runtime.spec.ts

@@ -2689,6 +2689,24 @@ describe('PythonCodeRuntime — budgets, termination, disposal', () => {
     expect(result.value).toBe("read: ''")
   }, 15_000)
 
+  it('keeps runtime type annotations unevaluated-as-strings when the program reads them', async () => {
+    // bootstrap.py imports `from __future__ import annotations`; without
+    // dont_inherit=True on compile(), that PEP 563 flag leaks into the program's
+    // compiled code and stringifies its type annotations, changing the semantics
+    // of a legal program that reads `f.__annotations__` at runtime.
+    const { runtime } = await setup()
+    const result = await runtime.run({
+      program: [
+        'def f(x: int) -> int:',
+        '    return x',
+        'return f.__annotations__["x"].__name__',
+      ].join('\n'),
+      bindings: [],
+    })
+    expect(result.error).toBeUndefined()
+    expect(result.value).toBe('int')
+  }, 15_000)
+
   it('reaps a same-group child that ignores SIGTERM and releases the pipes before close', async () => {
     // The same-group counterpart to the setsid-orphan case above. A descendant
     // left in the child's OWN process group (no setsid, so `kill(-pid)` reaches