diff --git a/MANIFEST.in b/MANIFEST.in
index 876aeeb7d..a0296c377 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,4 +1,9 @@
 graft skills
 graft optional-skills
+# Bundled plugin manifests (plugin.yaml / plugin.yml). Without these the
+# PluginManager scan (hermes_cli/plugins.py) finds zero plugins on installs
+# built from the sdist (e.g. Homebrew, downstream packagers). package-data
+# below covers the wheel; this covers the sdist. See #34034 / #28149.
+recursive-include plugins plugin.yaml plugin.yml
 global-exclude __pycache__
 global-exclude *.py[cod]
diff --git a/pyproject.toml b/pyproject.toml
index f2164724e..ce1b8b3da 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -226,6 +226,14 @@ plugins = [
   "*/dashboard/manifest.json",
   "*/dashboard/dist/*",
   "*/dashboard/dist/**/*",
+  # Plugin discovery (hermes_cli/plugins.py) reads a plugin.yaml/plugin.yml
+  # manifest from each bundled plugin directory to register it. Wheels only
+  # carry files declared here, so without this glob the wheel ships every
+  # plugin's Python code but none of its manifests — the scan finds zero
+  # plugins and all gateway platforms fail with "No adapter available for
+  # <platform>" (#34034), web-search providers go missing (#28149), etc.
+  "**/plugin.yaml",
+  "**/plugin.yml",
 ]
 
 [tool.setuptools.packages.find]
diff --git a/tests/test_packaging_metadata.py b/tests/test_packaging_metadata.py
index ce6d4793f..b53355f1c 100644
--- a/tests/test_packaging_metadata.py
+++ b/tests/test_packaging_metadata.py
@@ -20,3 +20,42 @@ def test_manifest_includes_bundled_skills():
 
     assert "graft skills" in manifest
     assert "graft optional-skills" in manifest
+
+
+def test_bundled_plugin_manifests_ship_in_both_wheel_and_sdist():
+    """Regression test for #34034 / #28149.
+
+    Plugin discovery (hermes_cli/plugins.py) registers each bundled plugin by
+    reading its ``plugin.yaml`` / ``plugin.yml`` manifest. Those manifests are
+    data files, not Python modules, so they only reach installed packages when
+    declared explicitly:
+
+    - wheel  -> ``[tool.setuptools.package-data]`` ``plugins`` glob
+    - sdist  -> ``MANIFEST.in`` (Homebrew and other downstream packagers build
+                from the sdist)
+
+    v0.15.0 declared neither, so the wheel shipped every adapter's Python code
+    but none of its manifests, and *every* gateway platform failed with
+    "No adapter available for <platform>". Both channels must cover manifests.
+    """
+    # There must actually be manifests on disk for the globs to match.
+    on_disk = list((REPO_ROOT / "plugins").rglob("plugin.yaml")) + list(
+        (REPO_ROOT / "plugins").rglob("plugin.yml")
+    )
+    assert on_disk, "expected bundled plugin manifests under plugins/"
+
+    # Wheel channel: package-data must declare a glob that matches plugin
+    # manifests anywhere under the plugins package.
+    data = tomllib.loads((REPO_ROOT / "pyproject.toml").read_text(encoding="utf-8"))
+    plugins_pkg_data = data["tool"]["setuptools"]["package-data"].get("plugins", [])
+    assert any(
+        g.endswith("plugin.yaml") or g.endswith("plugin.yml")
+        for g in plugins_pkg_data
+    ), "pyproject package-data 'plugins' must ship plugin.yaml/plugin.yml (wheel)"
+
+    # Sdist channel: MANIFEST.in must recursively include the manifests so
+    # downstream packagers building from the sdist also get them.
+    manifest = (REPO_ROOT / "MANIFEST.in").read_text(encoding="utf-8")
+    assert "recursive-include plugins" in manifest and "plugin.yaml" in manifest, (
+        "MANIFEST.in must recursive-include plugins plugin.yaml/plugin.yml (sdist)"
+    )