Migrate remaining 7 ref endpoints to SX, add :returns type annotations

Add 14 new IO primitives to boundary.sx: web interop (request-form,
request-json, request-header, request-content-type, request-args-all,
request-form-all, request-headers-all, request-file-name), response
manipulation (set-response-header, set-response-status), ephemeral
state (state-get, state-set!), and timing (now, sleep).

All 19 reference handlers now have :returns type annotations using
types.sx vocabulary. Response meta (headers/status) flows through
context vars, applied by register_route_handlers after execution.

Only SSE endpoint remains in Python (async generator paradigm).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

sx/bp/pages/routes.py

@@ -713,84 +713,9 @@ def register(url_prefix: str = "/") -> Blueprint:
     # Reference API endpoints — remaining Python-only
     #
     # Most reference endpoints migrated to sx/sx/handlers/ref-api.sx.
-    # These remain because they need Python-specific features:
-    #   - File upload access (request.files)
-    #   - Dynamic all-params iteration
-    #   - Stateful counters with non-200 responses
-    #   - SSE streaming
-    #   - Custom response headers
+    # SSE stays in Python — fundamentally different paradigm (async generator).
     # ------------------------------------------------------------------
 
-    def _ref_wire(wire_id: str, sx_src: str) -> str:
-        """Build OOB swap showing the wire response text."""
-        from sxc.pages.renders import _oob_code
-        return _oob_code(f"ref-wire-{wire_id}", sx_src)
-
-    @csrf_exempt
-    @bp.post("/geography/hypermedia/reference/api/upload-name")
-    async def ref_upload_name():
-        from shared.sx.helpers import sx_response
-        files = await request.files
-        f = files.get("file")
-        name = f.filename if f else "(no file)"
-        sx_src = f'(span :class "text-stone-800 text-sm" "Received: " (strong "{name}"))'
-        oob = _ref_wire("sx-encoding", sx_src)
-        return sx_response(f'(<> {sx_src} {oob})')
-
-    @bp.get("/geography/hypermedia/reference/api/echo-headers")
-    async def ref_echo_headers():
-        from shared.sx.helpers import sx_response
-        custom = [(k, v) for k, v in request.headers if k.lower().startswith("x-")]
-        if not custom:
-            sx_src = '(span :class "text-stone-400 text-sm" "No custom headers received.")'
-        else:
-            items = " ".join(
-                f'(li (strong "{k}") ": " "{v}")' for k, v in custom)
-            sx_src = f'(ul :class "text-sm text-stone-700 space-y-1" {items})'
-        oob = _ref_wire("sx-headers", sx_src)
-        return sx_response(f'(<> {sx_src} {oob})')
-
-    @bp.get("/geography/hypermedia/reference/api/echo-vals")
-    async def ref_echo_vals_get():
-        from shared.sx.helpers import sx_response
-        vals = list(request.args.items())
-        if not vals:
-            sx_src = '(span :class "text-stone-400 text-sm" "No values received.")'
-        else:
-            items = " ".join(
-                f'(li (strong "{k}") ": " "{v}")' for k, v in vals)
-            sx_src = f'(ul :class "text-sm text-stone-700 space-y-1" {items})'
-        oob_include = _ref_wire("sx-include", sx_src)
-        return sx_response(f'(<> {sx_src} {oob_include})')
-
-    @csrf_exempt
-    @bp.post("/geography/hypermedia/reference/api/echo-vals")
-    async def ref_echo_vals_post():
-        from shared.sx.helpers import sx_response
-        form = await request.form
-        vals = list(form.items())
-        if not vals:
-            sx_src = '(span :class "text-stone-400 text-sm" "No values received.")'
-        else:
-            items = " ".join(
-                f'(li (strong "{k}") ": " "{v}")' for k, v in vals)
-            sx_src = f'(ul :class "text-sm text-stone-700 space-y-1" {items})'
-        oob = _ref_wire("sx-vals", sx_src)
-        return sx_response(f'(<> {sx_src} {oob})')
-
-    _ref_flaky = {"n": 0}
-
-    @bp.get("/geography/hypermedia/reference/api/flaky")
-    async def ref_flaky():
-        from shared.sx.helpers import sx_response
-        _ref_flaky["n"] += 1
-        n = _ref_flaky["n"]
-        if n % 3 != 0:
-            return Response("", status=503, content_type="text/plain")
-        sx_src = f'(span :class "text-emerald-700 text-sm" "Success on attempt " "{n}" "!")'
-        oob = _ref_wire("sx-retry", sx_src)
-        return sx_response(f'(<> {sx_src} {oob})')
-
     @bp.get("/geography/hypermedia/reference/api/sse-time")
     async def ref_sse_time():
         async def generate():
@@ -930,24 +855,4 @@ def register(url_prefix: str = "/") -> Blueprint:
         )
         return sx_response(sx_src)
 
-    # --- Header demos ---
-
-    @bp.get("/geography/hypermedia/reference/api/trigger-event")
-    async def ref_trigger_event():
-        from shared.sx.helpers import sx_response
-        now = datetime.now().strftime("%H:%M:%S")
-        sx_src = f'(span :class "text-stone-800 text-sm" "Loaded at " (strong "{now}") " — check the border!")'
-        resp = sx_response(sx_src)
-        resp.headers["SX-Trigger"] = "showNotice"
-        return resp
-
-    @bp.get("/geography/hypermedia/reference/api/retarget")
-    async def ref_retarget():
-        from shared.sx.helpers import sx_response
-        now = datetime.now().strftime("%H:%M:%S")
-        sx_src = f'(span :class "text-violet-700 text-sm" "Retargeted at " (strong "{now}"))'
-        resp = sx_response(sx_src)
-        resp.headers["SX-Retarget"] = "#ref-hdr-retarget-alt"
-        return resp
-
     return bp