diff --git a/.claude/projects/-root-rose-ash/memory/feedback_sx_navigation.md b/.claude/projects/-root-rose-ash/memory/feedback_sx_navigation.md
new file mode 100644
index 0000000..060763c
--- /dev/null
+++ b/.claude/projects/-root-rose-ash/memory/feedback_sx_navigation.md
@@ -0,0 +1,17 @@
+---
+name: SX navigation single-source-of-truth
+description: Navigation must be defined once in nav-data.sx — no fragment URLs, no duplicated case statements, use make-page-fn for convention-based routing
+type: feedback
+---
+
+Never use fragment URLs (#anchors) in the SX docs nav system. Every navigable item must have its own Lisp URL.
+
+**Why:** Fragment URLs don't work with the SX URL routing system — fragments are client-side only and never reach the server, so nav resolution can't identify the current page.
+
+**How to apply:**
+- `nav-data.sx` is the single source of truth for all navigation labels, hrefs, summaries, and hierarchy
+- `page-functions.sx` uses `make-page-fn` (convention-based) or `slug->component` to derive component names from slugs — no hand-written case statements for simple pages
+- Overview/index pages should generate link lists from nav-data variables (e.g. `reactive-examples-nav-items`) rather than hardcoding URLs
+- To add a new simple page: add nav item to nav-data.sx, create the component file. That's it — the naming convention handles routing.
+- Pages that need server-side data fetching (reference, spec, test, bootstrapper, isomorphism) still use custom functions with explicit case clauses
+- Legacy Python nav lists in `content/pages.py` have been removed — nav-data.sx is canonical
diff --git a/hosts/ocaml/browser/test_page_render.js b/hosts/ocaml/browser/test_page_render.js
new file mode 100644
index 0000000..2acfe6f
--- /dev/null
+++ b/hosts/ocaml/browser/test_page_render.js
@@ -0,0 +1,18 @@
+const path = require("path");
+const fs = require("fs");
+require(path.join(__dirname, "../_build/default/browser/sx_browser.bc.js"));
+require(path.join(__dirname, "sx-platform.js"));
+const K = globalThis.SxKernel;
+for (const n of ["signals","deps","page-helpers","router","adapter-html"])
+  K.loadSource(fs.readFileSync(path.join(__dirname,`../../../web/${n}.sx`),"utf8"));
+K.loadSource(fs.readFileSync("/tmp/comp_defs.txt","utf8"));
+
+const pageSx = fs.readFileSync("/tmp/page_sx.txt","utf8");
+const parsed = K.parse(pageSx);
+const html = K.renderToHtml(parsed[0]);
+if (typeof html === "string" && !html.startsWith("Error:")) {
+  console.log("SUCCESS! Rendered", html.length, "chars of HTML");
+  console.log("Preview:", html.substring(0, 200));
+} else {
+  console.log("Error:", html);
+}
diff --git a/hosts/ocaml/browser/test_signals.js b/hosts/ocaml/browser/test_signals.js
new file mode 100644
index 0000000..495ced2
--- /dev/null
+++ b/hosts/ocaml/browser/test_signals.js
@@ -0,0 +1,25 @@
+const path = require("path");
+const fs = require("fs");
+require(path.join(__dirname, "../_build/default/browser/sx_browser.bc.js"));
+require(path.join(__dirname, "sx-platform.js"));
+const K = globalThis.SxKernel;
+for (const n of ["signals","deps","page-helpers","router","adapter-html"])
+  K.loadSource(fs.readFileSync(path.join(__dirname,`../../../web/${n}.sx`),"utf8"));
+
+// Test signal basics
+const tests = [
+  '(signal 42)',
+  '(let ((s (signal 42))) (deref s))',
+  '(let ((s (signal 42))) (reset! s 100) (deref s))',
+  '(let ((s (signal 10))) (swap! s (fn (v) (* v 2))) (deref s))',
+  '(let ((s (signal 0))) (computed (fn () (+ (deref s) 1))))',
+  '(let ((idx (signal 0))) (let ((c (computed (fn () (+ (deref idx) 10))))) (deref c)))',
+];
+
+for (const t of tests) {
+  const r = K.eval(t);
+  const s = JSON.stringify(r);
+  console.log(`${t.substring(0,60)}`);
+  console.log(`  => ${s && s.length > 100 ? s.substring(0,100) + '...' : s}`);
+  console.log();
+}
diff --git a/sx/sx/plans/runtime-slicing.sx b/sx/sx/plans/runtime-slicing.sx
index 58cc8d8..5a87086 100644
--- a/sx/sx/plans/runtime-slicing.sx
+++ b/sx/sx/plans/runtime-slicing.sx
@@ -40,7 +40,7 @@
     ;; -----------------------------------------------------------------------
 
     (~docs/section :title "Tiers" :id "tiers"
-      (p "Four tiers, matching the " (a :href "/sx/(geography.(reactive.plan))" :class "text-violet-700 underline" "reactive islands") " levels:")
+      (p "Four tiers, matching the " (a :href "/sx/(geography.(reactive.(reactive-design)))" :class "text-violet-700 underline" "reactive islands") " levels:")
 
       (div :class "overflow-x-auto rounded border border-stone-200 mb-4"
         (table :class "w-full text-left text-sm"
@@ -275,7 +275,7 @@
       (ul :class "list-disc pl-5 text-stone-700 space-y-1"
         (li (a :href "/sx/(etc.(plan.environment-images))" :class "text-violet-700 underline" "Environment Images") " — tiered images are smaller. An L0 image omits the parser, evaluator, and most primitives.")
         (li (a :href "/sx/(etc.(plan.content-addressed-components))" :class "text-violet-700 underline" "Content-Addressed Components") " — component CID resolution is L3-only. L0 pages don't resolve components client-side.")
-        (li (a :href "/sx/(geography.(reactive.plan))" :class "text-violet-700 underline" "Reactive Islands") " — L2 tier is defined by island presence. The signal runtime is the L1→L2 delta.")
+        (li (a :href "/sx/(geography.(reactive.(reactive-design)))" :class "text-violet-700 underline" "Reactive Islands") " — L2 tier is defined by island presence. The signal runtime is the L1→L2 delta.")
         (li (a :href "/sx/(etc.(plan.isomorphic-architecture))" :class "text-violet-700 underline" "Isomorphic Architecture") " — client-side page rendering is L3. Most pages don't need it."))
 
       (div :class "rounded border border-amber-200 bg-amber-50 p-3 mt-2"
diff --git a/sx/sxc/pages/helpers.py b/sx/sxc/pages/helpers.py
index 772c75e..086b3d3 100644
--- a/sx/sxc/pages/helpers.py
+++ b/sx/sxc/pages/helpers.py
@@ -159,18 +159,35 @@ def _reference_data(slug: str) -> dict:
     return build_reference_data(slug, raw, detail_keys)
 
 
-def _read_spec_file(filename: str) -> str:
-    """Read a spec .sx file from the ref directory. Pure I/O — metadata lives in .sx."""
+def _find_spec_file(filename: str) -> str | None:
+    """Find a spec .sx file across spec/, web/, shared/sx/ref/ directories."""
     import os
-    ref_dir = os.path.join(os.path.dirname(__file__), "..", "..", "shared", "sx", "ref")
-    if not os.path.isdir(ref_dir):
-        ref_dir = "/app/shared/sx/ref"
-    filepath = os.path.join(ref_dir, filename)
+    base = os.path.join(os.path.dirname(__file__), "..", "..")
+    search_dirs = [
+        os.path.join(base, "spec"),
+        os.path.join(base, "web"),
+        os.path.join(base, "shared", "sx", "ref"),
+        "/app/spec",
+        "/app/web",
+        "/app/shared/sx/ref",
+    ]
+    for d in search_dirs:
+        path = os.path.join(d, filename)
+        if os.path.isfile(path):
+            return path
+    return None
+
+
+def _read_spec_file(filename: str) -> str:
+    """Read a spec .sx file. Pure I/O — metadata lives in .sx."""
+    filepath = _find_spec_file(filename)
+    if not filepath:
+        return ";; spec file not found: " + filename
     try:
         with open(filepath, encoding="utf-8") as f:
             return f.read()
-    except FileNotFoundError:
-        return ";; spec file not found"
+    except (FileNotFoundError, TypeError):
+        return ";; spec file not found: " + filename
 
 
 # ---------------------------------------------------------------------------
@@ -332,7 +349,7 @@ def _collect_symbols(expr) -> set[str]:
 
 _SPEC_SLUG_MAP = {
     "parser": ("parser.sx", "Parser", "Tokenization and parsing"),
-    "evaluator": ("eval.sx", "Evaluator", "Tree-walking evaluation"),
+    "evaluator": ("evaluator.sx", "Evaluator", "CEK machine evaluator"),
     "primitives": ("primitives.sx", "Primitives", "Built-in pure functions"),
     "render": ("render.sx", "Renderer", "Three rendering modes"),
     "special-forms": ("special-forms.sx", "Special Forms", "Special form dispatch"),
@@ -374,10 +391,9 @@ def _spec_explorer_data(filename: str, title: str = "", desc: str = "") -> dict
         return None
 
     # Read the raw source
-    ref_dir = os.path.join(os.path.dirname(__file__), "..", "..", "shared", "sx", "ref")
-    if not os.path.isdir(ref_dir):
-        ref_dir = "/app/shared/sx/ref"
-    filepath = os.path.join(ref_dir, filename)
+    filepath = _find_spec_file(filename)
+    if not filepath:
+        return None
     try:
         with open(filepath, encoding="utf-8") as f:
             source = f.read()
diff --git a/sx/tests/test_demos.py b/sx/tests/test_demos.py
index cb1dc74..f62eaca 100644
--- a/sx/tests/test_demos.py
+++ b/sx/tests/test_demos.py
@@ -491,6 +491,15 @@ class TestSpecExplorer:
         assert "define" in body, "Should contain define forms from spec"
         assert "eval-expr" in body, "Should contain eval-expr from evaluator spec"
 
+    def test_evaluator_renders_in_browser(self, page: Page):
+        """Spec explorer should render correctly in the browser, not show 'not found'."""
+        nav(page, "(language.(spec.(explore.evaluator)))")
+        page.wait_for_timeout(3000)
+        content = page.locator("#main-panel").text_content() or ""
+        assert "not found" not in content.lower(), \
+            f"Page shows 'not found' instead of spec content: {content[:200]}"
+        expect(page.locator("#main-panel")).to_contain_text("Evaluator", timeout=5000)
+
 
 # ---------------------------------------------------------------------------
 # Key doc pages (smoke tests)