diff --git a/src/features/mcp/opencode-mcp.test.ts b/src/features/mcp/opencode-mcp.test.ts
index e47d56fcb..f2b357644 100644
--- a/src/features/mcp/opencode-mcp.test.ts
+++ b/src/features/mcp/opencode-mcp.test.ts
@@ -123,6 +123,58 @@ describe("OpencodeMcp", () => {
     });
   });
 
+  it.each(
+    [OpencodeMcp, Opencodev1Mcp, MimocodeMcp].flatMap((Mcp) =>
+      [false, true].flatMap((global) =>
+        (Mcp === MimocodeMcp ? [false] : [false, true]).flatMap((envelope) =>
+          ["a.b", "a_b"].map((serverName) => ({
+            name: Mcp.name,
+            Mcp,
+            global,
+            envelope,
+            serverName,
+          })),
+        ),
+      ),
+    ),
+  )(
+    "$name should ignore bare server prefixes (global=$global, envelope=$envelope, server=$serverName)",
+    ({ Mcp, global, envelope, serverName }) => {
+      const servers = { [serverName]: { type: "local", command: ["node"] } };
+      const mcp = new Mcp({
+        outputRoot: testDir,
+        relativeDirPath: ".",
+        relativeFilePath: "opencode.json",
+        global,
+        fileContent: JSON.stringify({
+          mcp: envelope ? { servers } : servers,
+          tools: {
+            a_b_: false,
+            a_b_read: true,
+            a_b_delete: false,
+            orphan_read: false,
+          },
+        }),
+      });
+      const imported = mcp.toRulesyncMcp().getJson();
+
+      expect(imported).toEqual({
+        $schema: RULESYNC_MCP_SCHEMA_URL,
+        mcpServers: {
+          [serverName]: {
+            type: "stdio",
+            command: "node",
+            enabledTools: ["read"],
+            disabledTools: ["delete"],
+          },
+        },
+        [Mcp === MimocodeMcp ? "mimocode" : Mcp === Opencodev1Mcp ? "opencodev1" : "opencode"]: {
+          mcpServers: { orphan: { disabledTools: ["read"] } },
+        },
+      });
+    },
+  );
+
   it("should attribute colliding sanitized server names to the first listed server", () => {
     const mcp = new OpencodeMcp({
       relativeDirPath: ".",
diff --git a/src/features/mcp/opencode-mcp.ts b/src/features/mcp/opencode-mcp.ts
index 5e093ce58..396c58853 100644
--- a/src/features/mcp/opencode-mcp.ts
+++ b/src/features/mcp/opencode-mcp.ts
@@ -220,11 +220,17 @@ function convertFromOpencodeFormat(
 ): McpServers {
   const serverNames = Object.keys(opencodeMcp);
   // Pre-filter with findOpencodeToolOwner so sanitized and legacy raw prefixes
-  // both count as owned. orphanMcpToolFiltersToRulesync then applies its own
-  // raw `<server>_` prefix check; that second pass is redundant for this
-  // caller but stays because Kilo still needs it.
+  // both count as owned. The owner lookup needs a nonempty tool suffix, so a
+  // bare sanitized prefix is dropped here as well; otherwise the orphan
+  // importer splits a_b_ into server a and tool b_ when the listed server is
+  // a.b. A bare raw prefix (a.b_) is left to the raw `<server>_` check in
+  // orphanMcpToolFiltersToRulesync, which Kilo also relies on.
   const orphanTools = Object.fromEntries(
-    Object.entries(tools ?? {}).filter(([key]) => !findOpencodeToolOwner({ key, serverNames })),
+    Object.entries(tools ?? {}).filter(
+      ([key]) =>
+        !findOpencodeToolOwner({ key, serverNames }) &&
+        !serverNames.some((serverName) => key === opencodeMcpToolPermissionKey(serverName, "")),
+    ),
   );
   return {
     ...orphanMcpToolFiltersToRulesync(opencodeMcp, orphanTools),