diff --git a/tests/e2e/README.md b/tests/e2e/README.md
index 0f53d2c2c..1fd962797 100644
--- a/tests/e2e/README.md
+++ b/tests/e2e/README.md
@@ -28,6 +28,8 @@ superproject support), or when not run from a git checkout.
 
 * `harness.py`: the git server, server-side repos & the repo client.
 * `test_init_sync.py`: core `repo init` & `repo sync` options.
+* `test_partial_clone.py`: partial clones, incl. the standard Android
+  configuration from go/repo-init & go/sync.
 * `test_sync_modes.py`: `sync -n`/`-l` & the other sync flags.
 * `test_workflows.py`: multi-step workflows.
 * `test_manifest_regressions.py`: manifests that broke users in the past.
diff --git a/tests/e2e/harness.py b/tests/e2e/harness.py
index 07252ad0d..73cfc92fd 100644
--- a/tests/e2e/harness.py
+++ b/tests/e2e/harness.py
@@ -74,6 +74,14 @@ REPO_SOURCE_BRANCH = "main"
 # the common `fetch=".."` resolves to the root of the host namespace.
 MANIFEST_REPO = "platform/manifest"
 
+# The git endpoints (relative to a repo URL) that clients request.
+REPO_ENDPOINTS = (
+    "info/refs",
+    "git-upload-pack",
+    "git-receive-pack",
+    "clone.bundle",
+)
+
 # Fixed identity used for all commits created by the harness (not by
 # the simulated user).
 HARNESS_IDENTITY = {
@@ -664,6 +672,21 @@ class ServerRepo:
         """Create an annotated tag."""
         self.git("tag", "-a", "-m", name, name, rev)
 
+    def commit_history_only_blob(
+        self, path: str, data: Union[str, bytes]
+    ) -> str:
+        """Commit `data` at `path`, then delete `path` in a second commit.
+
+        Partial clones only download such blobs if the filter allows it.
+
+        Returns:
+            The id of the blob (only reachable from history).
+        """
+        self.commit({path: data}, message=f"add {path}")
+        blob = self.git("rev-parse", f"{self.default_branch}:{path}")
+        self.commit({path: None}, message=f"delete {path}")
+        return blob
+
     def write_bundle(self) -> Path:
         """Write a clone.bundle (all branches & tags) served by the server."""
         bundle = self.path / "clone.bundle"
@@ -781,6 +804,42 @@ class GitHost:
         """All requests received for this namespace."""
         return self.server.requests_for(f"/{self.prefix}/")
 
+    def requests_for(
+        self, name: str, requests: Optional[List[Request]] = None
+    ) -> List[Request]:
+        """The requests for the repo `name` (out of `requests`, or all so far).
+
+        Args:
+            name: The repo name, e.g. `platform/foo`.
+            requests: Requests to filter, e.g. from `watch_requests`.
+        """
+        if requests is None:
+            requests = self.requests()
+        prefix = f"/{self.prefix}/{name}/"
+        return [r for r in requests if r.path.startswith(prefix)]
+
+    def requested_repos(
+        self, requests: Optional[List[Request]] = None
+    ) -> Set[str]:
+        """Return the names of the repos that received requests.
+
+        Args:
+            requests: Requests to inspect (e.g. from `watch_requests`), or all
+                requests received so far if None.
+        """
+        if requests is None:
+            requests = self.requests()
+        namespace = f"/{self.prefix}/"
+        names = set()
+        for request in requests:
+            if not request.path.startswith(namespace):
+                continue
+            for suffix in REPO_ENDPOINTS:
+                if request.path.endswith(f"/{suffix}"):
+                    names.add(request.path[len(namespace) : -len(suffix) - 1])
+                    break
+        return names
+
     @contextlib.contextmanager
     def watch_requests(self) -> Iterator[List[Request]]:
         """Collect the requests this namespace receives inside the block.
@@ -1006,6 +1065,34 @@ class RepoClient:
         """Whether HEAD in `path` is detached (not on a local branch)."""
         return self.git(path, "rev-parse", "--abbrev-ref", "HEAD") == "HEAD"
 
+    def config(self, path: str, key: str) -> Optional[str]:
+        """Return git config `key` of the checkout at `path` (None if unset).
+
+        Only the repo's own config is read (not e.g. the user's), and `path`
+        must be a git checkout.
+        """
+        proc = subprocess.run(
+            ["git", "config", "--local", "--get", key],
+            # See run_git for why this isn't a Path.
+            cwd=str(self.top / path),
+            env=self.env,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            check=False,
+            timeout=COMMAND_TIMEOUT,
+        )
+        # git exits 1 for unset keys; anything else (e.g. 128 outside of a
+        # repo) is a real error.
+        if proc.returncode == 1:
+            return None
+        if proc.returncode:
+            raise AssertionError(
+                f"git config --get {key} failed in {path} "
+                f"({proc.returncode}):\n"
+                f"{proc.stderr.decode('utf-8', 'replace')}"
+            )
+        return proc.stdout.decode("utf-8").rstrip("\r\n")
+
     def remote_branches(self, path: str) -> Set[str]:
         """Return the names of the `origin` remote-tracking branches."""
         out = self.git(
diff --git a/tests/e2e/test_harness.py b/tests/e2e/test_harness.py
index b25dc6763..d4da31cb9 100644
--- a/tests/e2e/test_harness.py
+++ b/tests/e2e/test_harness.py
@@ -16,13 +16,27 @@
 
 import http.client
 from pathlib import Path
-from typing import Mapping
+from typing import Mapping, Tuple
 import urllib.parse
 
 import harness
 import pytest
 
 
+def _http_request(
+    server: harness.GitHttpServer, method: str, path: str
+) -> Tuple[int, bytes]:
+    """Send a request to `server` & return the response status & body."""
+    url = urllib.parse.urlsplit(server.url)
+    conn = http.client.HTTPConnection(url.hostname, url.port, timeout=30)
+    try:
+        conn.request(method, path)
+        resp = conn.getresponse()
+        return resp.status, resp.read()
+    finally:
+        conn.close()
+
+
 @pytest.mark.parametrize(
     "key,value",
     [
@@ -135,3 +149,35 @@ def test_offline(git_server: harness.GitHttpServer) -> None:
         with host.offline():
             raise RuntimeError("boom")
     assert "refs/heads/main" in harness.run_git("ls-remote", repo.url)
+
+
+def test_requested_repos(git_server: harness.GitHttpServer) -> None:
+    """`requested_repos()` & `watch_requests()` track repo requests."""
+    host = harness.GitHost(git_server, "requested")
+    nested = host.create_repo("platform/nested", {"f": "x"})
+    top = host.create_repo("top", {"f": "x"})
+
+    harness.run_git("ls-remote", nested.url)
+    with host.watch_requests() as watched:
+        harness.run_git("ls-remote", top.url)
+        _http_request(git_server, "GET", f"/{host.prefix}/top/clone.bundle")
+
+    assert host.requested_repos() == {"platform/nested", "top"}
+    assert host.requested_repos(watched) == {"top"}
+    assert host.requests_for("platform/nested", watched) == []
+
+
+def test_client_config(tmp_path: Path) -> None:
+    """`RepoClient.config()` tells unset keys apart from errors."""
+    # Don't let git find a repo above tmp_path (e.g. with --basetemp).
+    env = dict(harness.clean_environ(), GIT_CEILING_DIRECTORIES=str(tmp_path))
+    client = harness.RepoClient(tmp_path / "client", harness.LAUNCHER, env, "")
+    repo = client.top / "repo"
+    harness.run_git("init", "-q", str(repo))
+    harness.run_git("config", "-f", str(repo / ".git/config"), "a.key", "val")
+    (client.top / "not-a-repo").mkdir()
+
+    assert client.config("repo", "a.key") == "val"
+    assert client.config("repo", "a.unset") is None
+    with pytest.raises(AssertionError, match="failed in not-a-repo"):
+        client.config("not-a-repo", "a.key")
diff --git a/tests/e2e/test_partial_clone.py b/tests/e2e/test_partial_clone.py
new file mode 100644
index 000000000..fe6204007
--- /dev/null
+++ b/tests/e2e/test_partial_clone.py
@@ -0,0 +1,294 @@
+# Copyright (C) 2026 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""E2E tests for partial clones, incl. the standard Android configuration."""
+
+import os
+from typing import Dict, List, NamedTuple, Tuple
+
+from harness import GIT_DEFAULTS_PARAMS
+from harness import GitHost
+from harness import Gitlink
+from harness import manifest_xml
+from harness import RepoClient
+from harness import ServerRepo
+import pytest
+
+
+# The go/repo-init flags.  The filter is 10M there; 10k keeps the test data
+# small without changing the semantics.
+ANDROID_INIT_ARGS = [
+    "-c",
+    "-b",
+    "main",
+    "--use-superproject",
+    "--partial-clone",
+    "--partial-clone-exclude=platform/frameworks/base",
+    "--clone-filter=blob:limit=10k",
+]
+
+# The go/sync flags.
+ANDROID_SYNC_ARGS = ["-c", "-j20", "--no-tags", "--optimized-fetch", "--prune"]
+
+# Larger than the 10k filter above, smaller than git's default big file
+# threshold so it's still delta compressed & packed normally.
+BIG = "x" * 20_000
+
+# The git config key holding a partial clone's filter.
+FILTER_KEY = "remote.origin.partialclonefilter"
+
+
+def create_with_big_history(host: GitHost, name: str) -> Tuple[ServerRepo, str]:
+    """Create `name` with a large blob that only exists in history.
+
+    Returns:
+        The repo and the id of the historical large blob.  The tip commit has
+        a different large blob (`big2.bin`) and a small file.
+    """
+    repo = host.create_repo(name, {"big.bin": BIG, "small": "s"})
+    big_blob = repo.git("rev-parse", "main:big.bin")
+    repo.commit({"big.bin": None, "big2.bin": BIG + "2"})
+    return repo, big_blob
+
+
+class AndroidTree(NamedTuple):
+    """The server side of `create_android_tree`, keyed by project path."""
+
+    repos: Dict[str, ServerRepo]
+    superproject: ServerRepo
+    # The commit the superproject pins each project to.
+    pins: Dict[str, str]
+    # A large blob that only exists in each project's history.
+    blobs: Dict[str, str]
+
+
+def create_android_tree(host: GitHost) -> AndroidTree:
+    """Create a small AOSP-like tree with a superproject.
+
+    `platform/foo` is a regular project and `platform/frameworks/base` is the
+    one go/repo-init excludes from the partial clone.  Both have moved past
+    the superproject's pins.
+    """
+    repos, pins, blobs = {}, {}, {}
+    for path in ("foo", "frameworks/base"):
+        name = f"platform/{path}"
+        repos[path], blobs[path] = create_with_big_history(host, name)
+        pins[path] = repos[path].rev_parse("main")
+    superproject = host.create_repo(
+        "platform/superproject",
+        {path: Gitlink(rev) for path, rev in pins.items()},
+    )
+    for repo in repos.values():
+        repo.commit({"small": "ahead"})
+        repo.commit({"small": "other"}, branch="other")
+    host.create_manifest(
+        manifest_xml(
+            '<superproject name="platform/superproject" />',
+            '<project name="platform/foo" path="foo" />',
+            '<project name="platform/frameworks/base" '
+            'path="frameworks/base" />',
+        )
+    )
+    return AndroidTree(repos, superproject, pins, blobs)
+
+
+def bundle_requests(host: GitHost) -> Dict[str, List[int]]:
+    """Map repo name to the status codes of its `clone.bundle` requests."""
+    result: Dict[str, List[int]] = {}
+    for r in host.requests():
+        if r.path.endswith("/clone.bundle"):
+            name = r.path[len(f"/{host.prefix}/") : -len("/clone.bundle")]
+            result.setdefault(name, []).append(r.status)
+    return result
+
+
+@pytest.mark.parametrize("git_defaults", GIT_DEFAULTS_PARAMS)
+def test_android_init_sync(host: GitHost, client: RepoClient) -> None:
+    """The go/repo-init flag combination followed by `repo sync -c -j32`.
+
+    Covers superproject pinning, `-c`, the clone filter on included projects,
+    no filter on the `--partial-clone-exclude`d project, and that historical
+    large blobs stay on the server while small historical blobs are fetched.
+    """
+    tree = create_android_tree(host)
+    small_history_blob = tree.repos["foo"].commit_history_only_blob(
+        "small_old.txt", b"small history"
+    )
+    new_foo_pin = tree.repos["foo"].rev_parse("main")
+    tree.superproject.commit({"foo": Gitlink(new_foo_pin)})
+    tree.repos["foo"].commit({"small": "unpinned"})
+    pins = dict(tree.pins, foo=new_foo_pin)
+
+    client.init(host.manifest_url, *ANDROID_INIT_ARGS)
+    assert client.sync("-c", "-j32").stderr == ""
+
+    # init persisted the settings later syncs depend on.
+    manifests = ".repo/manifests"
+    assert client.config(manifests, "repo.superproject") == "true"
+    assert client.config(manifests, "repo.partialclone") == "true"
+    assert client.config(manifests, "repo.clonefilter") == "blob:limit=10k"
+    assert (
+        client.config(manifests, "repo.partialcloneexclude")
+        == "platform/frameworks/base"
+    )
+    for path, pinned in pins.items():
+        assert client.head(path) == pinned
+        assert (client.top / path / "big2.bin").read_text() == BIG + "2"
+        assert client.remote_branches(path) == {"main"}
+    override = client.repodir / "exp-superproject/superproject_override.xml"
+    assert override.exists()
+    # The included project is a partial clone (git normalizes the size), so
+    # the large historical blob was never downloaded, while the small
+    # historical blob (under the 10k limit) was downloaded.
+    assert client.config("foo", "extensions.partialclone") == "origin"
+    assert client.config("foo", FILTER_KEY) == "blob:limit=10240"
+    assert not client.has_object("foo", tree.blobs["foo"])
+    assert client.has_object("foo", small_history_blob)
+    # The excluded project is a full clone.
+    assert client.config("frameworks/base", "extensions.partialclone") is None
+    assert client.config("frameworks/base", FILTER_KEY) is None
+    assert client.has_object("frameworks/base", tree.blobs["frameworks/base"])
+    # Partial clones disable clone bundles, but repo still requests one for
+    # excluded projects (this server has none).
+    assert bundle_requests(host) == {"platform/frameworks/base": [404]}
+
+
+@pytest.mark.parametrize("git_defaults", GIT_DEFAULTS_PARAMS)
+def test_android_sync_flags(host: GitHost, client: RepoClient) -> None:
+    """The go/sync flags on an initial & an incremental sync.
+
+    `-c -jN --no-tags --optimized-fetch --prune` on top of the go/repo-init
+    configuration.  The incremental sync must fetch a project whose pin moved
+    and skip one whose pin didn't.
+    """
+    tree = create_android_tree(host)
+    tree.repos["foo"].tag("v1", tree.pins["foo"])
+
+    client.init(host.manifest_url, *ANDROID_INIT_ARGS)
+    assert client.sync(*ANDROID_SYNC_ARGS).stderr == ""
+
+    for path, pinned in tree.pins.items():
+        assert client.head(path) == pinned
+        assert client.remote_branches(path) == {"main"}
+        assert client.tags(path) == set()
+
+    # Move foo's pin forward (on main) & tag it; frameworks/base keeps its pin.
+    new_pin = tree.repos["foo"].commit({"small": "new pin"})
+    tree.repos["foo"].tag("v2", new_pin)
+    tree.superproject.commit({"foo": Gitlink(new_pin)})
+    with host.watch_requests() as requests:
+        assert client.sync(*ANDROID_SYNC_ARGS).stderr == ""
+
+    assert client.head("foo") == new_pin
+    assert client.head("frameworks/base") == tree.pins["frameworks/base"]
+    assert client.tags("foo") == set()
+    assert (client.top / "foo/small").read_text() == "new pin"
+    # A project already at its (immutable) pin isn't fetched.
+    assert host.requested_repos(requests) == {
+        "platform/manifest",
+        "platform/superproject",
+        "platform/foo",
+    }
+
+
+def test_partial_clone_default_filter(
+    host: GitHost, client: RepoClient
+) -> None:
+    """`--partial-clone` alone uses `blob:none` & disables clone bundles."""
+    foo, big_blob = create_with_big_history(host, "platform/foo")
+    small_history = foo.commit_history_only_blob("old_small.txt", b"tiny")
+    small_tip = foo.git("rev-parse", "main:small")
+    foo.write_bundle()
+    host.create_manifest(manifest_xml('<project name="platform/foo" />'))
+
+    client.init(host.manifest_url, "--partial-clone")
+    client.sync()
+
+    path = "platform/foo"
+    assert client.config(".repo/manifests", "repo.partialclone") == "true"
+    assert client.config(".repo/manifests", "repo.clonefilter") == "blob:none"
+    assert client.config(".repo/manifests", FILTER_KEY) == "blob:none"
+    assert client.config(path, FILTER_KEY) == "blob:none"
+    assert client.config(path, "extensions.partialclone") == "origin"
+    # Blobs of the checked out tree were fetched on demand; history wasn't
+    # (even tiny blobs).
+    assert (client.top / path / "big2.bin").read_text() == BIG + "2"
+    assert client.has_object(path, small_tip)
+    assert not client.has_object(path, big_blob)
+    assert not client.has_object(path, small_history)
+    assert bundle_requests(host) == {}
+
+
+def test_partial_clone_two_phase_sync(
+    host: GitHost, client: RepoClient
+) -> None:
+    """`sync -n` then `sync -l` with a partial clone (initial & incremental).
+
+    The network phase fetches no blobs, so the local phase has to fetch the
+    checked out blobs on demand: `-l` isn't offline for partial clones.  When
+    the server is unreachable, `sync -l` fails cleanly & can be retried.
+    """
+    foo, big_blob = create_with_big_history(host, "platform/foo")
+    small_blob = foo.git("rev-parse", "main:small")
+    host.create_manifest(manifest_xml('<project name="platform/foo" />'))
+    client.init(host.manifest_url, "--partial-clone")
+
+    assert client.sync("-n").stderr == ""
+    path = "platform/foo"
+    assert not (client.top / path).exists()
+    gitdir = f"--git-dir={client.repodir / 'projects' / path}.git"
+    assert client.git(
+        ".", gitdir, "rev-parse", "refs/remotes/origin/main"
+    ) == foo.rev_parse("main")
+    objects = client.git(
+        ".",
+        gitdir,
+        "cat-file",
+        "--batch-check=%(objectname)",
+        "--batch-all-objects",
+    ).split()
+    assert foo.rev_parse("main") in objects
+    assert small_blob not in objects
+
+    # When the server is offline, `sync -l` fails cleanly without leaving a
+    # broken worktree behind.
+    with host.offline():
+        failed = client.sync("-l", check=False)
+    assert failed.returncode != 0
+    assert "Cannot initialize work tree for platform/foo" in failed.stderr
+    assert not os.path.lexists(client.top / path / ".git")
+
+    with host.watch_requests() as requests:
+        client.sync("-l")
+
+    assert client.head(path) == foo.rev_parse("main")
+    assert (client.top / path / "big2.bin").read_text() == BIG + "2"
+    assert client.has_object(path, small_blob)
+    assert not client.has_object(path, big_blob)
+    # The on-demand blob fetches are the only traffic of the local sync.
+    assert host.requested_repos(requests) == {"platform/foo"}
+
+    # Incremental `-n` then `-l` on the existing partial-clone checkout.
+    v2 = foo.commit({"small": "s2"})
+    s2_blob = foo.git("rev-parse", "main:small")
+    client.sync("-n")
+    assert (client.top / path / "small").read_text() == "s"
+    assert not client.has_object(path, s2_blob)
+
+    with host.watch_requests() as inc_requests:
+        client.sync("-l")
+    assert client.head(path) == v2
+    assert (client.top / path / "small").read_text() == "s2"
+    assert client.has_object(path, s2_blob)
+    assert host.requested_repos(inc_requests) == {"platform/foo"}