diff --git a/backend/build.py b/backend/build.py
new file mode 100644
index 0000000..3997b08
--- /dev/null
+++ b/backend/build.py
@@ -0,0 +1,56 @@
+"""Extract accepted assets without changing the Tea fallback; deterministic ZIP."""
+from pathlib import Path
+import zipfile
+import json
+import re
+ROOT = Path(__file__).resolve().parent
+REPO = ROOT.parent
+(ROOT / 'human_vault.py').write_bytes((REPO / 'tea_mcp/human_vault.py').read_bytes())
+html = (REPO / 'tea/web/🍊/index.html').read_text()
+html = html.replace('<script src="./app.js"', '<script type="module" src="./app.js"')
+html = html.replace('src="./app.js"', 'src="/assets/app.js"')
+html = html.replace('Available to you across Teahub.', '')
+html = re.sub(r'<div class="heroSupport">.*?</div>', '', html, flags=re.S)
+html = re.sub(r'<div class="scrim".*?<script', '<script', html, flags=re.S)
+html = re.sub(r'<div class="vaultGroup">\s*<div class="groupHead">\s*<div><strong>📦.*?</section>', '</section>', html, flags=re.S)
+html = html.replace('<div><h2>Your Persimmons</h2><div class="hint"><span id="userIdentity">Resolving signed-in user…</span></div></div>', '<h2>👤 My vault</h2>')
+html = html.replace('<button class="primary" id="addButton">+ Add</button>', '<a id="signInLink" class="buttonLink" href="/signin" hidden>Sign in</a>')
+html = re.sub(r'<div class="groupHead">\s*<div><strong>👤 My vault</strong>.*?<div class="groupRule" aria-hidden="true"></div>', '', html, count=1, flags=re.S)
+html = html.replace('<div id="userState" class="state">Loading…</div>', '<div id="userState" class="state" hidden></div>')
+html = html.replace('<span class="heroName">Persimmons</span>', '<span class="heroName"><span class="heroFruit">🍊</span>Persimmons</span>')
+html = html.replace('<div class="heroFlow" aria-label="Orange to water to robot">🍊 → 💧 → 🤖</div>', '')
+html = html.replace('</section>\n\n\n</main>', '''<div class="vaultGroup" id="namedVaults" hidden>
+  <div class="groupHead"><div><strong>📦 Vaults</strong><div class="hint">Private spaces for scoped Persimmons.</div></div><button id="newVault" class="primary">+ New vault</button></div>
+  <div class="groupRule" aria-hidden="true"></div>
+  <div id="namedVaultList" class="list" aria-live="polite"></div>
+</div>
+</section>
+<footer class="persimmonsFooter"><strong>Passwords, PATs &amp; plenty of other useful P’s.</strong><div class="vaultFlow" aria-label="Orange to water to robot">🍊 → 💧 → 🤖</div></footer>
+
+</main>''')
+html = html.replace(
+    '<div class="shellTop">\n  <h2>👤 My vault</h2>\n  <div class="shellActions"><button id="refreshAll">Refresh</button><button id="signOutButton" hidden>Sign out</button><a id="signInLink" class="buttonLink" href="/signin" hidden>Sign in</a></div>\n</div>',
+    '<div class="shellTop">\n  <div><h2>Vault</h2><div id="userIdentity" class="hint"></div></div>\n  <div class="shellActions"><button class="primary" id="addCredential" hidden>+ Add credential</button><button id="signOutButton" hidden>Sign out</button><a id="signInLink" class="buttonLink" href="/signin" hidden>Sign in</a></div>\n</div>'
+)
+html = html.replace('</style>', '''
+.juiceHover{outline:3px solid #ed9238;background:#fff1df}.connection[draggable=true]{cursor:grab}.juiceCard{padding:12px;margin-top:10px;border:1px solid var(--line);border-radius:10px}.juiceCard p{margin:6px 0;overflow-wrap:anywhere}\n.persimmonsFooter{text-align:center;margin:26px 0 0;color:var(--muted);font-size:12px;line-height:1.5}.persimmonsFooter strong{display:block;color:var(--ink);font-size:13px;margin-bottom:4px}.vaultFlow{font-size:15px;line-height:1.4;opacity:.72}
+.vaultSummary{display:flex;align-items:center;gap:10px;margin-bottom:12px}.lockIcon{font-size:22px;line-height:1}.vaultCount{color:var(--muted);font-size:12px}
+.credentialSource{display:flex;gap:6px;align-items:baseline;margin-top:10px;color:var(--muted);font-size:12px;overflow-wrap:anywhere}.credentialSource a{color:inherit}.credentialId{font-family:ui-monospace,SFMono-Regular,Menlo,monospace;text-transform:uppercase}
+#namedVaultList{display:grid;gap:10px}.namedVaultCard{padding:14px 16px}.namedVaultMeta{display:flex;align-items:center;gap:8px;flex-wrap:wrap;margin-top:8px}.namedVaultBadge{display:inline-flex;align-items:center;padding:3px 7px;border:1px solid var(--line);border-radius:999px;color:var(--muted);font-size:11px}.namedVaultActions{display:flex;gap:8px;flex-wrap:wrap;margin-top:12px}.namedVaultBody{margin-top:12px;padding:14px;border:1px dashed var(--line);border-radius:11px;color:var(--muted);font-size:12px;line-height:1.5}.namedVaultBody strong{display:block;color:var(--ink);margin-bottom:3px}
+@media(max-width:720px){.vaultSummary{align-items:flex-start}.shellActions .buttonLink,.shellActions button{flex:1}}
+</style>''')
+html = html.replace('<h2>Vault</h2>', '<h2>Master vault</h2>')
+# Keep the hero visually clean; supporting product copy lives in the footer.
+
+(ROOT / 'web/index.html').write_text(html)
+version = json.loads((REPO / 'persimmons-extension/manifest.json').read_text())['version']
+(ROOT / 'web/version.json').write_text(json.dumps({'version': version}) + '\n')
+with zipfile.ZipFile(ROOT / 'web/extension.zip', 'w', compression=zipfile.ZIP_DEFLATED) as archive:
+    for path in sorted((REPO / 'persimmons-extension').rglob('*')):
+        if 'tests' not in path.relative_to(REPO / 'persimmons-extension').parts and path.is_file() and path.suffix in {'.mjs', '.json', '.html', '.css', '.png'}:
+            entry = zipfile.ZipInfo('persimmons-extension/' + path.relative_to(REPO / 'persimmons-extension').as_posix(), (2026, 1, 1, 0, 0, 0))
+            entry.compress_type = zipfile.ZIP_DEFLATED
+            entry.external_attr = 0o644 << 16
+            archive.writestr(entry, path.read_bytes())
+
+(ROOT / 'web/version.mjs').write_bytes((REPO / 'persimmons-extension/version.mjs').read_bytes())