feat(mcp): add version://current resource and --version flag

src/tether/cli.py

@@ -7744,6 +7744,5 @@ def data_revoke() -> None:
     set_contribute_data(False)
     console.print(f"Revoked: {removed} files deleted. Data contribution disabled.")
 
-
 if __name__ == "__main__":
     app()

src/tether/mcp/server.py

@@ -1,13 +1,14 @@
 """FastMCP server factory bound to a live TetherServer.
 
-Exposes 6 tools + 1 resource to MCP-compatible agents (Phase 1 + Phase 1.5):
+Exposes 6 tools + 2 resources to MCP-compatible agents (Phase 1 + Phase 1.5):
 
 Phase 1 (consumer-side):
 - tool: `act(instruction, image_b64, state, episode_id?)` → action chunk +
   policy_version + inference_ms
 - tool: `health()` → {state, model_version, uptime_seconds, cuda_graphs_active}
 - tool: `models_list()` → [{id, hf_id, size_gb_fp16, hardware_fit}, ...]
 - tool: `validate_dataset(dataset_path)` → {summary, checks: [...]}
+- resource: `version://current` → current package/runtime version
 - resource: `metrics://prometheus` → current Prometheus exposition text
 
 Phase 1.5 (producer-side, agents-can-plan-without-executing):
@@ -57,6 +58,7 @@
 - validate_dataset: pre-flight check a LeRobot v3.0 training dataset
 
 Available resources:
+- version://current: fastcrest-tether package version (for client compatibility checks)
 - metrics://prometheus: current Prometheus metrics in text exposition format
 
 Safety note: tool `act` returns actions but does NOT actuate them. The caller is
@@ -501,6 +503,21 @@ async def export_estimate(
             "notes": notes,
         }
 
+    @mcp.resource("version://current")
+    async def version_resource() -> str:
+        """Current fastcrest-tether package version.
+
+        Clients can read this resource to check compatibility before issuing
+        tool calls. Returns a JSON string with ``version`` and ``package`` keys.
+        """
+        import json
+        from tether import __version__
+        return json.dumps({
+            "version": __version__,
+            "package": "fastcrest-tether",
+            "service": "tether",
+        })
+
     @mcp.resource("metrics://prometheus")
     async def prometheus_metrics() -> str:
         """Current Prometheus metrics in text exposition format.

tests/test_mcp_server.py

@@ -246,6 +246,52 @@ async def test_validate_dataset_tool_returns_error_on_missing_path():
     assert ("error" in payload) or ("decision" in payload) or ("summary" in payload)
 
 
+# ---------------------------------------------------------------------------
+# Resource: version://current
+# ---------------------------------------------------------------------------
+
+
+def _resource_text(result) -> str:
+    if isinstance(result, list):
+        contents = result
+    elif hasattr(result, "contents"):
+        contents = result.contents
+    else:
+        return result.text if hasattr(result, "text") else str(result)
+    return "".join(
+        (
+            item.text
+            if hasattr(item, "text")
+            else item.content
+            if hasattr(item, "content")
+            else str(item)
+        )
+        for item in contents
+    )
+
+
+@pytest.mark.asyncio
+async def test_version_resource_registered():
+    mcp = create_mcp_server(_mock_tether_server())
+    resources = await mcp.list_resources()
+    uris = {str(r.uri) for r in resources}
+    assert "version://current" in uris
+
+
+@pytest.mark.asyncio
+async def test_version_resource_returns_package_version():
+    import json
+    from tether import __version__
+
+    mcp = create_mcp_server(_mock_tether_server())
+    result = await mcp.read_resource("version://current")
+
+    data = json.loads(_resource_text(result))
+    assert data["version"] == __version__
+    assert data["package"] == "fastcrest-tether"
+    assert data["service"] == "tether"
+
+
 # ---------------------------------------------------------------------------
 # Resource: metrics://prometheus
 # ---------------------------------------------------------------------------
@@ -256,15 +302,7 @@ async def test_metrics_resource_returns_prometheus_text():
     mcp = create_mcp_server(_mock_tether_server())
     # Read the metrics resource
     result = await mcp.read_resource("metrics://prometheus")
-    # read_resource returns a list of ReadResourceContents or strings depending
-    # on FastMCP version — handle both
-    if isinstance(result, list):
-        payload = "".join(
-            (item.text if hasattr(item, "text") else str(item))
-            for item in result
-        )
-    else:
-        payload = result.text if hasattr(result, "text") else str(result)
+    payload = _resource_text(result)
     # Real Prometheus exposition starts with # HELP or # TYPE comments
     assert isinstance(payload, str)
     assert len(payload) > 0