diff --git a/.github/workflows/eval-refresh.yml b/.github/workflows/eval-refresh.yml
index 24c16b7d..33df2ff7 100644
--- a/.github/workflows/eval-refresh.yml
+++ b/.github/workflows/eval-refresh.yml
@@ -515,14 +515,6 @@ jobs:
           urls=$(gh pr list --head "$GITHUB_REF_NAME" --state open --json url,isCrossRepository --jq '.[] | select(.isCrossRepository == false) | .url' | paste -sd ' ' -)
           echo "PR_URLS=$urls" >> "$GITHUB_ENV"
 
-      - name: Upload results to Braintrust
-        # A Braintrust outage shouldn't block publishing results.
-        continue-on-error: true
-        env:
-          BRAINTRUST_API_KEY: ${{ secrets.BRAINTRUST_API_KEY }}
-          BRAINTRUST_PROJECT_ID: ${{ secrets.BRAINTRUST_PROJECT_ID }}
-        run: pnpm upload-braintrust --runs "${{ needs.prepare.outputs.runs }}"
-
       - name: Upload exported results
         if: github.event_name == 'pull_request' || github.event_name == 'workflow_dispatch'
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
diff --git a/evals/docs-nav/lib/navigation.test.ts b/evals/docs-nav/lib/navigation.test.ts
index 9e6f658d..e6fc39cb 100644
--- a/evals/docs-nav/lib/navigation.test.ts
+++ b/evals/docs-nav/lib/navigation.test.ts
@@ -491,6 +491,15 @@ describe('scoreDocsNav on a tree test', () => {
     });
   });
 
+  it('allows opening a second-level section straight from the top', async () => {
+    const { navigation } = await treeNavigationOf([
+      openSection('root'),
+      openSection('2.1'),
+      choosePage('2.1.1'),
+    ]);
+    expect(navigation).toMatchObject({ reached: true, noWrongTurns: true });
+  });
+
   it('counts going back up the path as a wrong turn', async () => {
     const { navigation } = await treeNavigationOf([
       openSection('root'),
diff --git a/evals/docs-nav/lib/navigation.ts b/evals/docs-nav/lib/navigation.ts
index 54666ac7..689ee969 100644
--- a/evals/docs-nav/lib/navigation.ts
+++ b/evals/docs-nav/lib/navigation.ts
@@ -248,10 +248,9 @@ function treePrefixes(id: string): string[] {
   return parts.map((_, index) => parts.slice(0, index + 1).join('.'));
 }
 
-function isTreeChild(id: string, parent: string): boolean {
-  if (parent === TREE_ROOT) return id !== TREE_ROOT && !id.includes('.');
-  const rest = id.startsWith(`${parent}.`) ? id.slice(parent.length + 1) : '';
-  return rest !== '' && !rest.includes('.');
+function isTreeDescendant(id: string, parent: string): boolean {
+  if (parent === TREE_ROOT) return id !== TREE_ROOT;
+  return id.startsWith(`${parent}.`);
 }
 
 function isTreeCall(call: ToolCallRecord): boolean {
@@ -311,7 +310,7 @@ async function scoreTreeRun(
     }
     opened.push(label(id));
     const isStart = current === null && id === TREE_ROOT;
-    if (!isStart && (!onPath.has(id) || !isTreeChild(id, current ?? ''))) {
+    if (!isStart && (!onPath.has(id) || !isTreeDescendant(id, current ?? ''))) {
       wrongTurns.push(label(id));
     }
     current = id;
diff --git a/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-2-revised.experiment.ts b/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-2-revised.experiment.ts
new file mode 100644
index 00000000..3bdcf0c7
--- /dev/null
+++ b/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-2-revised.experiment.ts
@@ -0,0 +1,9 @@
+import { docsNavExperiment } from './lib/docs-nav-experiment.js';
+
+export default docsNavExperiment({
+  variant: 'option-1',
+  tree: true,
+  topLevels: 2,
+  origin:
+    'https://docs-git-docs-ia-option-1-placement-revisions-supabase.vercel.app',
+});
diff --git a/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-2-subheads.experiment.ts b/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-2-subheads.experiment.ts
new file mode 100644
index 00000000..e9ad4acb
--- /dev/null
+++ b/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-2-subheads.experiment.ts
@@ -0,0 +1,8 @@
+import { docsNavExperiment } from './lib/docs-nav-experiment.js';
+
+export default docsNavExperiment({
+  variant: 'option-1',
+  tree: true,
+  topLevels: 2,
+  origin: 'https://docs-git-docs-ia-option-1-subheads-supabase.vercel.app',
+});
diff --git a/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-2.experiment.ts b/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-2.experiment.ts
new file mode 100644
index 00000000..b3f286e9
--- /dev/null
+++ b/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-2.experiment.ts
@@ -0,0 +1,7 @@
+import { docsNavExperiment } from './lib/docs-nav-experiment.js';
+
+export default docsNavExperiment({
+  variant: 'option-1',
+  tree: true,
+  topLevels: 2,
+});
diff --git a/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-revised.experiment.ts b/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-revised.experiment.ts
new file mode 100644
index 00000000..1803cd78
--- /dev/null
+++ b/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-revised.experiment.ts
@@ -0,0 +1,8 @@
+import { docsNavExperiment } from './lib/docs-nav-experiment.js';
+
+export default docsNavExperiment({
+  variant: 'option-1',
+  tree: true,
+  origin:
+    'https://docs-git-docs-ia-option-1-placement-revisions-supabase.vercel.app',
+});
diff --git a/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-subheads.experiment.ts b/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-subheads.experiment.ts
new file mode 100644
index 00000000..da70ed9f
--- /dev/null
+++ b/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-option-1-tree-subheads.experiment.ts
@@ -0,0 +1,7 @@
+import { docsNavExperiment } from './lib/docs-nav-experiment.js';
+
+export default docsNavExperiment({
+  variant: 'option-1',
+  tree: true,
+  origin: 'https://docs-git-docs-ia-option-1-subheads-supabase.vercel.app',
+});
diff --git a/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-tree-2.experiment.ts b/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-tree-2.experiment.ts
new file mode 100644
index 00000000..29f62663
--- /dev/null
+++ b/experiments/docs-nav/claude-code-sonnet-5.5-docs-nav-tree-2.experiment.ts
@@ -0,0 +1,3 @@
+import { docsNavExperiment } from './lib/docs-nav-experiment.js';
+
+export default docsNavExperiment({ tree: true, topLevels: 2 });
diff --git a/experiments/docs-nav/lib/docs-nav-experiment.ts b/experiments/docs-nav/lib/docs-nav-experiment.ts
index d30c009b..47112234 100644
--- a/experiments/docs-nav/lib/docs-nav-experiment.ts
+++ b/experiments/docs-nav/lib/docs-nav-experiment.ts
@@ -9,6 +9,9 @@ import {
 
 export type DocsVariant = 'option-1';
 
+const DOCS_ORIGIN =
+  'https://docs-git-docs-today-nav-pre-split-baseline-supabase.vercel.app';
+
 const source = (file: string) =>
   readFileSync(new URL(file, import.meta.url), 'utf8');
 
@@ -18,11 +21,15 @@ const TREE_NAVIGATOR_SOURCE = source('./docs-tree-navigator.mjs');
 interface DocsNavOptions {
   variant?: DocsVariant;
   tree?: boolean;
+  origin?: string;
+  topLevels?: number;
 }
 
 function docsNavigatorMcpServer({
   variant,
   tree,
+  origin = DOCS_ORIGIN,
+  topLevels,
 }: DocsNavOptions): McpServerDefinition {
   return {
     name: tree ? 'docs-tree-navigator' : 'docs-navigator',
@@ -37,6 +44,8 @@ function docsNavigatorMcpServer({
           ],
           env: {
             [tree ? 'DOCS_TREE_NAVIGATOR_SERVE' : 'DOCS_NAVIGATOR_SERVE']: '1',
+            DOCS_ORIGIN: origin,
+            ...(topLevels ? { DOCS_TREE_TOP_LEVELS: String(topLevels) } : {}),
             ...(variant ? { DOCS_IA_VARIANT: variant } : {}),
           },
         },
diff --git a/experiments/docs-nav/lib/docs-navigator.mjs b/experiments/docs-nav/lib/docs-navigator.mjs
index d4424ad0..ab33da29 100644
--- a/experiments/docs-nav/lib/docs-navigator.mjs
+++ b/experiments/docs-nav/lib/docs-navigator.mjs
@@ -29,8 +29,9 @@ function stripTags(html) {
 }
 
 export function createNavigator({ env, fetch }) {
+  const origin = env.DOCS_ORIGIN?.replace(/\/+$/, '') ?? SITE;
   const variant = env.DOCS_IA_VARIANT;
-  const root = `${SITE}/docs`;
+  const root = `${origin}/docs`;
   const allowed = new Set([root]);
 
   function canonicalUrl(url, base) {
@@ -40,10 +41,11 @@ export function createNavigator({ env, fetch }) {
     } catch {
       return null;
     }
-    if (parsed.origin !== SITE) return null;
+    if (parsed.origin !== SITE && parsed.origin !== origin) return null;
     const path = parsed.pathname.replace(/\.md$/, '').replace(/\/+$/, '');
     if (ASSET_PATTERN.test(path)) return null;
-    return `${SITE}${path}`;
+    const isDocs = path === '/docs' || path.startsWith('/docs/');
+    return `${isDocs ? origin : SITE}${path}`;
   }
 
   function requestUrl(url) {
diff --git a/experiments/docs-nav/lib/docs-tree-navigator.d.mts b/experiments/docs-nav/lib/docs-tree-navigator.d.mts
index e3257c6f..291f939e 100644
--- a/experiments/docs-nav/lib/docs-tree-navigator.d.mts
+++ b/experiments/docs-nav/lib/docs-tree-navigator.d.mts
@@ -20,7 +20,8 @@ export declare function treeUrl(
 
 export declare function createTreeSession(
   tree: { name: string; root: TreeNode },
-  url: string
+  url: string,
+  options?: { topLevels?: number }
 ): {
   open(id: unknown): TreeReply;
   choose(id: unknown): TreeReply;
diff --git a/experiments/docs-nav/lib/docs-tree-navigator.mjs b/experiments/docs-nav/lib/docs-tree-navigator.mjs
index 43e24c21..745f4bca 100644
--- a/experiments/docs-nav/lib/docs-tree-navigator.mjs
+++ b/experiments/docs-nav/lib/docs-tree-navigator.mjs
@@ -41,7 +41,7 @@ function kind(node) {
   return '';
 }
 
-export function createTreeSession(tree, url) {
+export function createTreeSession(tree, url, { topLevels = 1 } = {}) {
   const visible = new Set([ROOT]);
   let chosen = null;
 
@@ -64,14 +64,22 @@ export function createTreeSession(tree, url) {
         `${node.label} is a page, not a section. Choose it with ${CHOOSE_TOOL} if it's where you'd find the answer.`
       );
     }
-    node.children.forEach((_, index) => {
-      visible.add(childId(id, index));
-    });
+    const peek = id === ROOT && topLevels >= 2;
+    const line = (child, childKey, indent) =>
+      `${indent}- [${childKey}] ${child.label}${kind(child)}${child.description ? `\n${indent}  ${child.description}` : ''}`;
     const items = node.children
-      .map(
-        (child, index) =>
-          `- [${childId(id, index)}] ${child.label}${kind(child)}${child.description ? `\n  ${child.description}` : ''}`
-      )
+      .flatMap((child, index) => {
+        const key = childId(id, index);
+        visible.add(key);
+        const below = peek
+          ? (child.children ?? []).map((grandchild, inner) => {
+              const innerKey = childId(key, inner);
+              visible.add(innerKey);
+              return line(grandchild, innerKey, '  ');
+            })
+          : [];
+        return [line(child, key, ''), ...below];
+      })
       .join('\n');
     return {
       text: [
@@ -138,7 +146,11 @@ function serve() {
       if (!res.ok) throw new Error(`Couldn't load ${url}: HTTP ${res.status}`);
       return res.json();
     })
-    .then((tree) => createTreeSession(tree, url));
+    .then((tree) =>
+      createTreeSession(tree, url, {
+        topLevels: Number(process.env.DOCS_TREE_TOP_LEVELS ?? 1),
+      })
+    );
   const send = (message) =>
     process.stdout.write(`${JSON.stringify(message)}\n`);
   const reply = ({ isError, text }) => ({
diff --git a/experiments/docs-nav/lib/docs-tree-navigator.test.ts b/experiments/docs-nav/lib/docs-tree-navigator.test.ts
index 3f3ecfa2..8fc25ae1 100644
--- a/experiments/docs-nav/lib/docs-tree-navigator.test.ts
+++ b/experiments/docs-nav/lib/docs-tree-navigator.test.ts
@@ -79,4 +79,13 @@ describe('createTreeSession', () => {
     expect(chosen.text).toContain(`Tree: ${URL}`);
     expect(session.choose('2').isError).toBe(true);
   });
+
+  it('shows the second level under each top-level section when asked', () => {
+    const session = createTreeSession(TREE, URL, { topLevels: 2 });
+    const top = session.open('root').text;
+    expect(top).toContain('  - [1.1] Network (a page, and a section)');
+    expect(top).not.toContain('SSL enforcement');
+    expect(session.open('1.1').isError).toBeUndefined();
+    expect(session.choose('1.2').isError).toBeUndefined();
+  });
 });
diff --git a/experiments/docs-nav/lib/print-report.ts b/experiments/docs-nav/lib/print-report.ts
index e4c0d918..dae40c41 100644
--- a/experiments/docs-nav/lib/print-report.ts
+++ b/experiments/docs-nav/lib/print-report.ts
@@ -13,6 +13,16 @@ const ARMS: Record<string, string> = {
   'claude-code-sonnet-5.5-docs-nav-option-1': 'option-1',
   'claude-code-sonnet-5.5-docs-nav-tree': 'control tree',
   'claude-code-sonnet-5.5-docs-nav-option-1-tree': 'option-1 tree',
+  'claude-code-sonnet-5.5-docs-nav-option-1-tree-subheads':
+    'option-1 tree subheads',
+  'claude-code-sonnet-5.5-docs-nav-tree-2': 'control tree 2 levels',
+  'claude-code-sonnet-5.5-docs-nav-option-1-tree-2': 'option-1 tree 2 levels',
+  'claude-code-sonnet-5.5-docs-nav-option-1-tree-2-subheads':
+    'option-1 tree 2 levels subheads',
+  'claude-code-sonnet-5.5-docs-nav-option-1-tree-revised':
+    'option-1 tree revised',
+  'claude-code-sonnet-5.5-docs-nav-option-1-tree-2-revised':
+    'option-1 tree 2 levels revised',
 };
 
 const arms: Record<string, ArmRuns> = Object.fromEntries(