URL restructure, 404 page, trailing slash normalization, layout fixes

- Rename /reactive-islands/ → /reactive/, /reference/ → /hypermedia/reference/,
  /examples/ → /hypermedia/examples/ across all .sx and .py files
- Add 404 error page (not-found.sx) working on both server refresh and
  client-side SX navigation via orchestration.sx error response handling
- Add trailing slash redirect (GET only, excludes /api/, /static/, /internal/)
- Remove blue sky-500 header bar from SX docs layout (conditional on header-rows)
- Fix 405 on API endpoints from trailing slash redirect hitting POST/PUT/DELETE
- Fix client-side 404: orchestration.sx now swaps error response content
  instead of silently dropping it
- Add new plan files and home page component

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

shared/sx/ref/sx_ref.py

@@ -1198,7 +1198,7 @@ RENDER_HTML_FORMS = ['if', 'when', 'cond', 'case', 'let', 'let*', 'begin', 'do',
 is_render_html_form = lambda name: contains_p(RENDER_HTML_FORMS, name)
 
 # render-list-to-html
-render_list_to_html = lambda expr, env: ('' if sx_truthy(empty_p(expr)) else (lambda head: (join('', map(lambda x: render_value_to_html(x, env), expr)) if sx_truthy((not sx_truthy((type_of(head) == 'symbol')))) else (lambda name: (lambda args: (join('', map(lambda x: render_to_html(x, env), args)) if sx_truthy((name == '<>')) else (join('', map(lambda x: sx_str(trampoline(eval_expr(x, env))), args)) if sx_truthy((name == 'raw!')) else (render_html_lake(args, env) if sx_truthy((name == 'lake')) else (render_html_element(name, args, env) if sx_truthy(contains_p(HTML_TAGS, name)) else (render_html_island(env_get(env, name), args, env) if sx_truthy((starts_with_p(name, '~') if not sx_truthy(starts_with_p(name, '~')) else (env_has(env, name) if not sx_truthy(env_has(env, name)) else is_island(env_get(env, name))))) else ((lambda val: (render_html_component(val, args, env) if sx_truthy(is_component(val)) else (render_to_html(expand_macro(val, args, env), env) if sx_truthy(is_macro(val)) else error(sx_str('Unknown component: ', name)))))(env_get(env, name)) if sx_truthy(starts_with_p(name, '~')) else (dispatch_html_form(name, expr, env) if sx_truthy(is_render_html_form(name)) else (render_to_html(expand_macro(env_get(env, name), args, env), env) if sx_truthy((env_has(env, name) if not sx_truthy(env_has(env, name)) else is_macro(env_get(env, name)))) else render_value_to_html(trampoline(eval_expr(expr, env)), env))))))))))(rest(expr)))(symbol_name(head))))(first(expr)))
+render_list_to_html = lambda expr, env: ('' if sx_truthy(empty_p(expr)) else (lambda head: (join('', map(lambda x: render_value_to_html(x, env), expr)) if sx_truthy((not sx_truthy((type_of(head) == 'symbol')))) else (lambda name: (lambda args: (join('', map(lambda x: render_to_html(x, env), args)) if sx_truthy((name == '<>')) else (join('', map(lambda x: sx_str(trampoline(eval_expr(x, env))), args)) if sx_truthy((name == 'raw!')) else (render_html_lake(args, env) if sx_truthy((name == 'lake')) else (render_html_marsh(args, env) if sx_truthy((name == 'marsh')) else (render_html_element(name, args, env) if sx_truthy(contains_p(HTML_TAGS, name)) else (render_html_island(env_get(env, name), args, env) if sx_truthy((starts_with_p(name, '~') if not sx_truthy(starts_with_p(name, '~')) else (env_has(env, name) if not sx_truthy(env_has(env, name)) else is_island(env_get(env, name))))) else ((lambda val: (render_html_component(val, args, env) if sx_truthy(is_component(val)) else (render_to_html(expand_macro(val, args, env), env) if sx_truthy(is_macro(val)) else error(sx_str('Unknown component: ', name)))))(env_get(env, name)) if sx_truthy(starts_with_p(name, '~')) else (dispatch_html_form(name, expr, env) if sx_truthy(is_render_html_form(name)) else (render_to_html(expand_macro(env_get(env, name), args, env), env) if sx_truthy((env_has(env, name) if not sx_truthy(env_has(env, name)) else is_macro(env_get(env, name)))) else render_value_to_html(trampoline(eval_expr(expr, env)), env)))))))))))(rest(expr)))(symbol_name(head))))(first(expr)))
 
 # dispatch-html-form
 dispatch_html_form = lambda name, expr, env: ((lambda cond_val: (render_to_html(nth(expr, 2), env) if sx_truthy(cond_val) else (render_to_html(nth(expr, 3), env) if sx_truthy((len(expr) > 3)) else '')))(trampoline(eval_expr(nth(expr, 1), env))) if sx_truthy((name == 'if')) else (('' if sx_truthy((not sx_truthy(trampoline(eval_expr(nth(expr, 1), env))))) else join('', map(lambda i: render_to_html(nth(expr, i), env), range(2, len(expr))))) if sx_truthy((name == 'when')) else ((lambda branch: (render_to_html(branch, env) if sx_truthy(branch) else ''))(eval_cond(rest(expr), env)) if sx_truthy((name == 'cond')) else (render_to_html(trampoline(eval_expr(expr, env)), env) if sx_truthy((name == 'case')) else ((lambda local: join('', map(lambda i: render_to_html(nth(expr, i), local), range(2, len(expr)))))(process_bindings(nth(expr, 1), env)) if sx_truthy(((name == 'let') if sx_truthy((name == 'let')) else (name == 'let*'))) else (join('', map(lambda i: render_to_html(nth(expr, i), env), range(1, len(expr)))) if sx_truthy(((name == 'begin') if sx_truthy((name == 'begin')) else (name == 'do'))) else (_sx_begin(trampoline(eval_expr(expr, env)), '') if sx_truthy(is_definition_form(name)) else ((lambda f: (lambda coll: join('', map(lambda item: (render_lambda_html(f, [item], env) if sx_truthy(is_lambda(f)) else render_to_html(apply(f, [item]), env)), coll)))(trampoline(eval_expr(nth(expr, 2), env))))(trampoline(eval_expr(nth(expr, 1), env))) if sx_truthy((name == 'map')) else ((lambda f: (lambda coll: join('', map_indexed(lambda i, item: (render_lambda_html(f, [i, item], env) if sx_truthy(is_lambda(f)) else render_to_html(apply(f, [i, item]), env)), coll)))(trampoline(eval_expr(nth(expr, 2), env))))(trampoline(eval_expr(nth(expr, 1), env))) if sx_truthy((name == 'map-indexed')) else (render_to_html(trampoline(eval_expr(expr, env)), env) if sx_truthy((name == 'filter')) else ((lambda f: (lambda coll: join('', map(lambda item: (render_lambda_html(f, [item], env) if sx_truthy(is_lambda(f)) else render_to_html(apply(f, [item]), env)), coll)))(trampoline(eval_expr(nth(expr, 2), env))))(trampoline(eval_expr(nth(expr, 1), env))) if sx_truthy((name == 'for-each')) else render_value_to_html(trampoline(eval_expr(expr, env)), env))))))))))))
@@ -1221,6 +1221,15 @@ def render_html_lake(args, env):
     reduce(lambda state, arg: (lambda skip: (assoc(state, 'skip', False, 'i', (get(state, 'i') + 1)) if sx_truthy(skip) else ((lambda kname: (lambda kval: _sx_begin((_sx_cell_set(_cells, 'lake_id', kval) if sx_truthy((kname == 'id')) else (_sx_cell_set(_cells, 'lake_tag', kval) if sx_truthy((kname == 'tag')) else NIL)), assoc(state, 'skip', True, 'i', (get(state, 'i') + 1))))(trampoline(eval_expr(nth(args, (get(state, 'i') + 1)), env))))(keyword_name(arg)) if sx_truthy(((type_of(arg) == 'keyword') if not sx_truthy((type_of(arg) == 'keyword')) else ((get(state, 'i') + 1) < len(args)))) else _sx_begin(_sx_append(children, arg), assoc(state, 'i', (get(state, 'i') + 1))))))(get(state, 'skip')), {'i': 0, 'skip': False}, args)
     return sx_str('<', _cells['lake_tag'], ' data-sx-lake="', escape_attr((_cells['lake_id'] if sx_truthy(_cells['lake_id']) else '')), '">', join('', map(lambda c: render_to_html(c, env), children)), '</', _cells['lake_tag'], '>')
 
+# render-html-marsh
+def render_html_marsh(args, env):
+    _cells = {}
+    _cells['marsh_id'] = NIL
+    _cells['marsh_tag'] = 'div'
+    children = []
+    reduce(lambda state, arg: (lambda skip: (assoc(state, 'skip', False, 'i', (get(state, 'i') + 1)) if sx_truthy(skip) else ((lambda kname: (lambda kval: _sx_begin((_sx_cell_set(_cells, 'marsh_id', kval) if sx_truthy((kname == 'id')) else (_sx_cell_set(_cells, 'marsh_tag', kval) if sx_truthy((kname == 'tag')) else (NIL if sx_truthy((kname == 'transform')) else NIL))), assoc(state, 'skip', True, 'i', (get(state, 'i') + 1))))(trampoline(eval_expr(nth(args, (get(state, 'i') + 1)), env))))(keyword_name(arg)) if sx_truthy(((type_of(arg) == 'keyword') if not sx_truthy((type_of(arg) == 'keyword')) else ((get(state, 'i') + 1) < len(args)))) else _sx_begin(_sx_append(children, arg), assoc(state, 'i', (get(state, 'i') + 1))))))(get(state, 'skip')), {'i': 0, 'skip': False}, args)
+    return sx_str('<', _cells['marsh_tag'], ' data-sx-marsh="', escape_attr((_cells['marsh_id'] if sx_truthy(_cells['marsh_id']) else '')), '">', join('', map(lambda c: render_to_html(c, env), children)), '</', _cells['marsh_tag'], '>')
+
 # render-html-island
 render_html_island = lambda island, args, env: (lambda kwargs: (lambda children: _sx_begin(reduce(lambda state, arg: (lambda skip: (assoc(state, 'skip', False, 'i', (get(state, 'i') + 1)) if sx_truthy(skip) else ((lambda val: _sx_begin(_sx_dict_set(kwargs, keyword_name(arg), val), assoc(state, 'skip', True, 'i', (get(state, 'i') + 1))))(trampoline(eval_expr(nth(args, (get(state, 'i') + 1)), env))) if sx_truthy(((type_of(arg) == 'keyword') if not sx_truthy((type_of(arg) == 'keyword')) else ((get(state, 'i') + 1) < len(args)))) else _sx_begin(_sx_append(children, arg), assoc(state, 'i', (get(state, 'i') + 1))))))(get(state, 'skip')), {'i': 0, 'skip': False}, args), (lambda local: (lambda island_name: _sx_begin(for_each(lambda p: _sx_dict_set(local, p, (dict_get(kwargs, p) if sx_truthy(dict_has(kwargs, p)) else NIL)), component_params(island)), (_sx_dict_set(local, 'children', make_raw_html(join('', map(lambda c: render_to_html(c, env), children)))) if sx_truthy(component_has_children(island)) else NIL), (lambda body_html: (lambda state_json: sx_str('<span data-sx-island="', escape_attr(island_name), '"', (sx_str(' data-sx-state="', escape_attr(state_json), '"') if sx_truthy(state_json) else ''), '>', body_html, '</span>'))(serialize_island_state(kwargs)))(render_to_html(component_body(island), local))))(component_name(island)))(env_merge(component_closure(island), env))))([]))({})
 
@@ -1237,7 +1246,7 @@ render_to_sx = lambda expr, env: (lambda result: (result if sx_truthy((type_of(r
 aser = lambda expr, env: _sx_case(type_of(expr), [('number', lambda: expr), ('string', lambda: expr), ('boolean', lambda: expr), ('nil', lambda: NIL), ('symbol', lambda: (lambda name: (env_get(env, name) if sx_truthy(env_has(env, name)) else (get_primitive(name) if sx_truthy(is_primitive(name)) else (True if sx_truthy((name == 'true')) else (False if sx_truthy((name == 'false')) else (NIL if sx_truthy((name == 'nil')) else error(sx_str('Undefined symbol: ', name))))))))(symbol_name(expr))), ('keyword', lambda: keyword_name(expr)), ('list', lambda: ([] if sx_truthy(empty_p(expr)) else aser_list(expr, env))), (None, lambda: expr)])
 
 # aser-list
-aser_list = lambda expr, env: (lambda head: (lambda args: (map(lambda x: aser(x, env), expr) if sx_truthy((not sx_truthy((type_of(head) == 'symbol')))) else (lambda name: (aser_fragment(args, env) if sx_truthy((name == '<>')) else (aser_call(name, args, env) if sx_truthy(starts_with_p(name, '~')) else (aser_call(name, args, env) if sx_truthy((name == 'lake')) else (aser_call(name, args, env) if sx_truthy(contains_p(HTML_TAGS, name)) else (aser_special(name, expr, env) if sx_truthy((is_special_form(name) if sx_truthy(is_special_form(name)) else is_ho_form(name))) else (aser(expand_macro(env_get(env, name), args, env), env) if sx_truthy((env_has(env, name) if not sx_truthy(env_has(env, name)) else is_macro(env_get(env, name)))) else (lambda f: (lambda evaled_args: (apply(f, evaled_args) if sx_truthy((is_callable(f) if not sx_truthy(is_callable(f)) else ((not sx_truthy(is_lambda(f))) if not sx_truthy((not sx_truthy(is_lambda(f)))) else ((not sx_truthy(is_component(f))) if not sx_truthy((not sx_truthy(is_component(f)))) else (not sx_truthy(is_island(f))))))) else (trampoline(call_lambda(f, evaled_args, env)) if sx_truthy(is_lambda(f)) else (aser_call(sx_str('~', component_name(f)), args, env) if sx_truthy(is_component(f)) else (aser_call(sx_str('~', component_name(f)), args, env) if sx_truthy(is_island(f)) else error(sx_str('Not callable: ', inspect(f))))))))(map(lambda a: trampoline(eval_expr(a, env)), args)))(trampoline(eval_expr(head, env))))))))))(symbol_name(head))))(rest(expr)))(first(expr))
+aser_list = lambda expr, env: (lambda head: (lambda args: (map(lambda x: aser(x, env), expr) if sx_truthy((not sx_truthy((type_of(head) == 'symbol')))) else (lambda name: (aser_fragment(args, env) if sx_truthy((name == '<>')) else (aser_call(name, args, env) if sx_truthy(starts_with_p(name, '~')) else (aser_call(name, args, env) if sx_truthy((name == 'lake')) else (aser_call(name, args, env) if sx_truthy((name == 'marsh')) else (aser_call(name, args, env) if sx_truthy(contains_p(HTML_TAGS, name)) else (aser_special(name, expr, env) if sx_truthy((is_special_form(name) if sx_truthy(is_special_form(name)) else is_ho_form(name))) else (aser(expand_macro(env_get(env, name), args, env), env) if sx_truthy((env_has(env, name) if not sx_truthy(env_has(env, name)) else is_macro(env_get(env, name)))) else (lambda f: (lambda evaled_args: (apply(f, evaled_args) if sx_truthy((is_callable(f) if not sx_truthy(is_callable(f)) else ((not sx_truthy(is_lambda(f))) if not sx_truthy((not sx_truthy(is_lambda(f)))) else ((not sx_truthy(is_component(f))) if not sx_truthy((not sx_truthy(is_component(f)))) else (not sx_truthy(is_island(f))))))) else (trampoline(call_lambda(f, evaled_args, env)) if sx_truthy(is_lambda(f)) else (aser_call(sx_str('~', component_name(f)), args, env) if sx_truthy(is_component(f)) else (aser_call(sx_str('~', component_name(f)), args, env) if sx_truthy(is_island(f)) else error(sx_str('Not callable: ', inspect(f))))))))(map(lambda a: trampoline(eval_expr(a, env)), args)))(trampoline(eval_expr(head, env)))))))))))(symbol_name(head))))(rest(expr)))(first(expr))
 
 # aser-fragment
 aser_fragment = lambda children, env: (lambda parts: ('' if sx_truthy(empty_p(parts)) else sx_str('(<> ', join(' ', map(serialize, parts)), ')')))(filter(lambda x: (not sx_truthy(is_nil(x))), map(lambda c: aser(c, env), children)))
@@ -1410,6 +1419,12 @@ def with_island_scope(scope_fn, body_fn):
 # register-in-scope
 register_in_scope = lambda disposable: (_island_scope(disposable) if sx_truthy(_island_scope) else NIL)
 
+# with-marsh-scope
+with_marsh_scope = lambda marsh_el, body_fn: (lambda disposers: _sx_begin(with_island_scope(lambda d: _sx_append(disposers, d), body_fn), dom_set_data(marsh_el, 'sx-marsh-disposers', disposers)))([])
+
+# dispose-marsh-scope
+dispose_marsh_scope = lambda marsh_el: (lambda disposers: (_sx_begin(for_each(lambda d: invoke(d), disposers), dom_set_data(marsh_el, 'sx-marsh-disposers', NIL)) if sx_truthy(disposers) else NIL))(dom_get_data(marsh_el, 'sx-marsh-disposers'))
+
 # *store-registry*
 _store_registry = {}