diff --git a/CLAUDE.md b/CLAUDE.md
index 636b8deb..bf139926 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -173,12 +173,12 @@ Two files make the vouch repo loadable directly as an OpenClaw plugin
 
 * [`openclaw.plugin.json`](./openclaw.plugin.json) — the manifest the
   loader parses: `id` + `configSchema` (required), `kind: context-engine`,
-  `version`, and `skills` (directories under `adapters/openclaw/skills/`,
-  one SKILL.md each; OpenClaw publishes them as skills *and* slash
-  commands).
+  `version`, the `openclaw.compat.pluginApi` floor, and `skills`
+  (directories under `adapters/openclaw/skills/`, one SKILL.md each;
+  OpenClaw publishes them as skills *and* slash commands).
 * [`package.json`](./package.json) — loader-facing only: the
   `openclaw.extensions` pointer at the JS entry module and the
-  `openclaw.compat.pluginApi` floor. The Python package stays in
+  matching `openclaw.compat.pluginApi` floor. The Python package stays in
   `pyproject.toml`.
 
 Invariants, all enforced by `tests/test_openclaw_plugin_manifest.py`:
diff --git a/openclaw.plugin.json b/openclaw.plugin.json
index ffcd470d..b2d853d6 100644
--- a/openclaw.plugin.json
+++ b/openclaw.plugin.json
@@ -4,6 +4,11 @@
   "version": "1.2.2",
   "description": "Git-native, review-gated knowledge base. Registers vouch's context engine (cited retrieval + salience reflex + hot memory) and the vouch skills. The kb.* MCP server is deployment config: `openclaw mcp add vouch -- vouch serve`.",
   "kind": "context-engine",
+  "openclaw": {
+    "compat": {
+      "pluginApi": ">=2026.6.0"
+    }
+  },
   "skills": [
     "adapters/openclaw/skills"
   ],
diff --git a/schemas/capabilities.schema.json b/schemas/capabilities.schema.json
index b986604e..803f9411 100644
--- a/schemas/capabilities.schema.json
+++ b/schemas/capabilities.schema.json
@@ -12,6 +12,17 @@
       "title": "Context Engines",
       "type": "array"
     },
+    "host_compat": {
+      "additionalProperties": {
+        "additionalProperties": {
+          "type": "string"
+        },
+        "type": "object"
+      },
+      "description": "Host compatibility metadata keyed by host/plugin id.",
+      "title": "Host Compat",
+      "type": "object"
+    },
     "knowledge_capability": {
       "additionalProperties": true,
       "title": "Knowledge Capability",
diff --git a/src/vouch/capabilities.py b/src/vouch/capabilities.py
index 3fd21c75..f5b5d642 100644
--- a/src/vouch/capabilities.py
+++ b/src/vouch/capabilities.py
@@ -11,6 +11,8 @@
 from .models import Capabilities
 from .openclaw.context_engine import describe_engine
 
+OPENCLAW_PLUGIN_API = ">=2026.6.0"
+
 # The full method surface this implementation exposes. Keep this list in
 # sync with the MCP server + JSONL server registrations — `test_capabilities`
 # asserts they match.
@@ -98,4 +100,5 @@ def capabilities() -> Capabilities:
             "config_path": "retrieval.scope",
         },
         context_engines=[describe_engine()],
+        host_compat={"openclaw": {"pluginApi": OPENCLAW_PLUGIN_API}},
     )
diff --git a/src/vouch/models.py b/src/vouch/models.py
index dccf4453..2d7fd401 100644
--- a/src/vouch/models.py
+++ b/src/vouch/models.py
@@ -457,3 +457,7 @@ class Capabilities(BaseModel):
         default_factory=list,
         description="OpenClaw context engines exposed (see openclaw.plugin.json)",
     )
+    host_compat: dict[str, dict[str, str]] = Field(
+        default_factory=dict,
+        description="Host compatibility metadata keyed by host/plugin id.",
+    )
diff --git a/tests/test_capabilities.py b/tests/test_capabilities.py
index 736b20ba..19fb8197 100644
--- a/tests/test_capabilities.py
+++ b/tests/test_capabilities.py
@@ -2,9 +2,20 @@
 
 from __future__ import annotations
 
+import json
+from pathlib import Path
+
 from vouch import capabilities
 from vouch.jsonl_server import HANDLERS
 
+REPO_ROOT = Path(__file__).resolve().parents[1]
+MANIFEST_PATH = REPO_ROOT / "openclaw.plugin.json"
+
+
+def _manifest_plugin_api() -> str:
+    manifest = json.loads(MANIFEST_PATH.read_text(encoding="utf-8"))
+    return manifest["openclaw"]["compat"]["pluginApi"]
+
 
 def test_capabilities_matches_jsonl_handlers() -> None:
     caps = capabilities.capabilities()
@@ -15,3 +26,15 @@ def test_capabilities_matches_jsonl_handlers() -> None:
         f"missing handlers={declared - implemented}, "
         f"missing capabilities={implemented - declared}"
     )
+
+
+def test_capabilities_host_compat_matches_openclaw_manifest() -> None:
+    caps = capabilities.capabilities()
+    manifest_range = _manifest_plugin_api()
+    assert caps.host_compat["openclaw"]["pluginApi"] == manifest_range
+
+
+def test_capabilities_host_compat_present_and_nonempty() -> None:
+    caps = capabilities.capabilities()
+    assert "openclaw" in caps.host_compat
+    assert caps.host_compat["openclaw"]["pluginApi"]
diff --git a/tests/test_openclaw_plugin_manifest.py b/tests/test_openclaw_plugin_manifest.py
index d67b35bc..7aee762b 100644
--- a/tests/test_openclaw_plugin_manifest.py
+++ b/tests/test_openclaw_plugin_manifest.py
@@ -101,6 +101,12 @@ def test_package_json_declares_entry_and_compat(package_json: dict) -> None:
     assert openclaw["compat"]["pluginApi"]
 
 
+def test_manifest_declares_openclaw_compat(manifest: dict, package_json: dict) -> None:
+    assert manifest["openclaw"]["compat"]["pluginApi"] == (
+        package_json["openclaw"]["compat"]["pluginApi"]
+    )
+
+
 def test_manifest_skills_are_publishable_dirs(manifest: dict) -> None:
     """Each skills entry must resolve to dirs OpenClaw can publish.
 
@@ -144,7 +150,6 @@ def test_manifest_carries_no_dead_dialect_fields(manifest: dict) -> None:
         "mcpServers",
         "shared_deps",
         "excluded_from_install",
-        "openclaw",
         "contracts",
     )
     for dead in dead_fields: