diff --git a/datasette/app.py b/datasette/app.py
index e6d070ea..da36c3f3 100644
--- a/datasette/app.py
+++ b/datasette/app.py
@@ -3048,6 +3048,50 @@ class DatasetteRouter:
             receive,
             max_post_body_bytes=self.ds.setting("max_post_body_bytes"),
         )
+        match, view = resolve_routes(self.routes, path)
+        is_static = view is favicon or getattr(view, "_datasette_static", False)
+        original_send = send
+
+        async def send(message):
+            if message["type"] == "http.response.start" and not (
+                is_static and message["status"] in (200, 304)
+            ):
+                # Decide privacy after rendering, including for streaming responses
+                # and error handlers. A public primary resource can still include
+                # private labels, actor navigation, or cookie-dependent content.
+                headers = list(message.get("headers", []))
+                personalized = (
+                    request.actor is not None
+                    or "cookie" in request.headers
+                    or "authorization" in request.headers
+                    or any(key.lower() == b"set-cookie" for key, _ in headers)
+                )
+                if personalized:
+                    headers = [
+                        (key, value)
+                        for key, value in headers
+                        if key.lower() != b"cache-control"
+                    ]
+                    headers.append((b"cache-control", b"private, no-store"))
+
+                # Anonymous responses must not be reused for credentialed requests.
+                # Preserve any additional variation specified by views or plugins.
+                vary = [
+                    part.strip()
+                    for key, value in headers
+                    if key.lower() == b"vary"
+                    for part in value.split(b",")
+                    if part.strip()
+                ]
+                if b"*" not in vary:
+                    for name in (b"Cookie", b"Authorization"):
+                        if name.lower() not in {part.lower() for part in vary}:
+                            vary.append(name)
+                headers = [(k, v) for k, v in headers if k.lower() != b"vary"]
+                headers.append((b"vary", b", ".join(vary)))
+                message = dict(message, headers=headers)
+            await original_send(message)
+
         # Populate request_messages if ds_messages cookie is present
         try:
             request._messages = self.ds.unsign(
@@ -3087,8 +3131,7 @@ class DatasetteRouter:
             return await self.handle_401(request, send, token_error)
         scope_modifications["actor"] = actor or default_actor
         scope = dict(scope, **scope_modifications)
-
-        match, view = resolve_routes(self.routes, path)
+        request.scope = scope
 
         if match is None:
             return await self.handle_404(request, send)
diff --git a/datasette/utils/asgi.py b/datasette/utils/asgi.py
index 2614ad02..6dac071b 100644
--- a/datasette/utils/asgi.py
+++ b/datasette/utils/asgi.py
@@ -498,6 +498,8 @@ def asgi_static(root_path, chunk_size=4096, headers=None, content_type=None):
             await asgi_send_html(send, "404: File not found", 404)
             return
 
+    # Only the actual static-file handler can bypass dynamic response privacy.
+    inner_static._datasette_static = True
     return inner_static
 
 
diff --git a/docs/settings.rst b/docs/settings.rst
index 5fd05d33..9fd51554 100644
--- a/docs/settings.rst
+++ b/docs/settings.rst
@@ -256,6 +256,8 @@ Default HTTP caching max-age header in seconds, used for ``Cache-Control: max-ag
 
     datasette mydatabase.db --setting default_cache_ttl 60
 
+Dynamic responses for authenticated actors, requests with cookies or an ``Authorization`` header, and responses that set cookies use ``Cache-Control: private, no-store``. This takes precedence over ``default_cache_ttl`` and ``?_ttl=``, even when cache headers are otherwise disabled. Anonymous dynamic responses vary by ``Cookie`` and ``Authorization``. Static assets retain their own cache policy.
+
 .. _setting_cache_size_kb:
 
 cache_size_kb
diff --git a/tests/test_stored_queries.py b/tests/test_stored_queries.py
index 4be96b30..e0b0e6c6 100644
--- a/tests/test_stored_queries.py
+++ b/tests/test_stored_queries.py
@@ -208,11 +208,12 @@ def test_custom_params(stored_write_client):
     )
 
 
-def test_stored_query_pages_no_vary_header(stored_write_client):
-    # These pages no longer embed per-cookie CSRF tokens, so they must not
-    # set Vary: Cookie - they should be cacheable across users.
-    assert "vary" not in stored_write_client.get("/data").headers
-    assert "vary" not in stored_write_client.get("/data/update_name").headers
+def test_stored_query_pages_vary_by_credentials(stored_write_client):
+    # Even without per-cookie CSRF tokens, anonymous pages must not be reused
+    # for authenticated users whose permissions or navigation can differ.
+    for path in ("/data", "/data/update_name"):
+        response = stored_write_client.get(path)
+        assert response.headers["vary"] == "Cookie, Authorization"
 
 
 def test_json_post_body(stored_write_client):