Add register_sx_layout infrastructure, convert account/federation/orders

Phase 0: Add _ctx_to_env() and render_to_sx_with_env() to shared/sx/helpers.py,
register_sx_layout() to shared/sx/layouts.py, and ~root-header/~root-mobile
wrapper defcomps to layout.sx. Convert built-in "root" layout to .sx.

Phases 1-3: Convert account (65→19 lines), federation (105→97 lines),
and orders (88→21 lines) to use register_sx_layout with .sx defcomps
that read ctx values as free variables from the evaluation environment.
No more Python building SX strings via SxExpr(await root_header_sx(ctx)).

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

federation/sx/layouts.sx

@@ -0,0 +1,17 @@
+;; Federation layout defcomps — read ctx values from env free variables.
+;; `actor` is injected into env by the layout registration in __init__.py.
+
+;; Full page: root header + social header in header-child
+(defcomp ~social-layout-full ()
+  (<> (~root-header)
+    (~header-child-sx
+      :inner (~federation-social-header
+               :nav (~federation-social-nav :actor actor)))))
+
+;; OOB (HTMX): social header oob + root header oob
+(defcomp ~social-layout-oob ()
+  (<> (~oob-header-sx
+        :parent-id "root-header-child"
+        :row (~federation-social-header
+               :nav (~federation-social-nav :actor actor)))
+    (~root-header :oob true)))

federation/sxc/pages/__init__.py

@@ -17,7 +17,7 @@ def _load_federation_page_files() -> None:
 
 
 # ---------------------------------------------------------------------------
-# Layouts
+# Layouts — .sx defcomps read free variables from env
 # ---------------------------------------------------------------------------
 
 def _register_federation_layouts() -> None:
@@ -25,36 +25,30 @@ def _register_federation_layouts() -> None:
     register_custom_layout("social", _social_full, _social_oob)
 
 
-async def _social_full(ctx: dict, **kw: Any) -> str:
-    from shared.sx.helpers import root_header_sx, header_child_sx, render_to_sx
-    from shared.sx.parser import SxExpr
-
+def _actor_data(ctx: dict) -> dict | None:
     actor = ctx.get("actor")
-    actor_data = _serialize_actor(actor) if actor else None
-    nav = await render_to_sx("federation-social-nav", actor=actor_data)
-    social_hdr = await render_to_sx("federation-social-header", nav=SxExpr(nav))
-    root_hdr = await root_header_sx(ctx)
-    child = await header_child_sx(social_hdr)
-    return "(<> " + root_hdr + " " + child + ")"
+    if not actor:
+        return None
+    from services.federation_page import _serialize_actor
+    return _serialize_actor(actor)
+
+
+async def _social_full(ctx: dict, **kw: Any) -> str:
+    from shared.sx.helpers import render_to_sx_with_env, _ctx_to_env
+    env = _ctx_to_env(ctx)
+    env["actor"] = kw.get("actor") or _actor_data(ctx)
+    return await render_to_sx_with_env("social-layout-full", env)
 
 
 async def _social_oob(ctx: dict, **kw: Any) -> str:
-    from shared.sx.helpers import root_header_sx, render_to_sx
-    from shared.sx.parser import SxExpr
-
-    actor = ctx.get("actor")
-    actor_data = _serialize_actor(actor) if actor else None
-    nav = await render_to_sx("federation-social-nav", actor=actor_data)
-    social_hdr = await render_to_sx("federation-social-header", nav=SxExpr(nav))
-    child_oob = await render_to_sx("oob-header-sx",
-                         parent_id="root-header-child",
-                         row=SxExpr(social_hdr))
-    root_hdr_oob = await root_header_sx(ctx, oob=True)
-    return "(<> " + child_oob + " " + root_hdr_oob + ")"
+    from shared.sx.helpers import render_to_sx_with_env, _ctx_to_env
+    env = _ctx_to_env(ctx, oob=True)
+    env["actor"] = kw.get("actor") or _actor_data(ctx)
+    return await render_to_sx_with_env("social-layout-oob", env)
 
 
 # ---------------------------------------------------------------------------
-# Serializers and helpers — still used by layouts and route handlers
+# Helpers still used by route handlers
 # ---------------------------------------------------------------------------
 
 def _serialize_actor(actor) -> dict | None:
@@ -78,16 +72,12 @@ def _serialize_remote_actor(a) -> dict:
 async def _social_page(ctx: dict, actor, *, content: str,
                        title: str = "Rose Ash", meta_html: str = "") -> str:
     """Build a full social page with social header."""
-    from shared.sx.helpers import render_to_sx, root_header_sx, header_child_sx, full_page_sx
-    from shared.sx.parser import SxExpr
+    from shared.sx.helpers import render_to_sx_with_env, _ctx_to_env, full_page_sx
     from markupsafe import escape
 
-    actor_data = _serialize_actor(actor)
-    nav = await render_to_sx("federation-social-nav", actor=actor_data)
-    social_hdr = await render_to_sx("federation-social-header", nav=SxExpr(nav))
-    hdr = await root_header_sx(ctx)
-    child = await header_child_sx(social_hdr)
-    header_rows = "(<> " + hdr + " " + child + ")"
+    env = _ctx_to_env(ctx)
+    env["actor"] = _serialize_actor(actor) if actor else None
+    header_rows = await render_to_sx_with_env("social-layout-full", env)
     return await full_page_sx(ctx, header_rows=header_rows, content=content,
                           meta_html=meta_html or f'<title>{escape(title)}</title>')