fix(update): carry candidate plugin API version through doctor

src/cli/update-cli.test.ts

@@ -2365,12 +2365,21 @@ describe("update-cli", () => {
         termination: "exit",
       };
     });
+    readPackageVersion.mockImplementation(async (packageRoot: string) => {
+      const manifest = JSON.parse(
+        await fs.readFile(path.join(packageRoot, "package.json"), "utf-8"),
+      ) as { version?: string };
+      return manifest.version ?? "0.0.0";
+    });
 
     await updateCommand({ yes: true });
 
     const doctorCall = doctorCommandCall();
     expect(doctorCall?.[0].slice(1)).toEqual([entryPath, "doctor", "--non-interactive", "--fix"]);
     expect(doctorCall?.[1].cwd).toBe(pkgRoot);
+    expect(
+      (doctorCall?.[1].env as NodeJS.ProcessEnv | undefined)?.OPENCLAW_COMPATIBILITY_HOST_VERSION,
+    ).toBe("2026.5.14");
     expect(defaultRuntime.exit).not.toHaveBeenCalledWith(1);
   });
 

src/cli/update-cli/update-command.ts

@@ -1403,6 +1403,7 @@ async function runPackageInstallUpdate(params: {
       const entryPath = await resolveGatewayInstallEntrypoint(verifiedPackageRoot);
       if (entryPath) {
         await createUpdateConfigSnapshot();
+        const candidateHostVersion = await readPackageVersion(verifiedPackageRoot);
         return await runUpdateStep({
           name: `${CLI_NAME} doctor`,
           argv: [
@@ -1421,6 +1422,7 @@ async function runPackageInstallUpdate(params: {
             OPENCLAW_UPDATE_IN_PROGRESS: "1",
             [UPDATE_DEFER_CONFIGURED_PLUGIN_INSTALL_REPAIR_ENV]: "1",
             [UPDATE_PARENT_SUPPORTS_DOCTOR_CONFIG_WRITE_ENV]: "1",
+            OPENCLAW_COMPATIBILITY_HOST_VERSION: candidateHostVersion,
           },
           timeoutMs: params.timeoutMs,
           progress: params.progress,