feat: add a feature to link subgraphs across namespaces

cli/src/commands/mcp/tools/subgraph-verify-schema-changes.ts

@@ -48,6 +48,8 @@ export const registerSubgraphVerifySchemaChangesTool = ({ server, opts }: ToolCo
                   clientTrafficCheckSkipped: resp.clientTrafficCheckSkipped === true,
                   hasProposalMatchError:
                     resp.response?.code === EnumStatusCode.ERR_SCHEMA_MISMATCH_WITH_APPROVED_PROPOSAL,
+                  isLinkedTrafficCheckFailed: resp.isLinkedTrafficCheckFailed,
+                  isLinkedPruningCheckFailed: resp.isLinkedPruningCheckFailed,
                 }),
               },
               null,
@@ -68,6 +70,8 @@ const isCheckSuccessful = ({
   hasGraphPruningErrors,
   clientTrafficCheckSkipped,
   hasProposalMatchError,
+  isLinkedTrafficCheckFailed,
+  isLinkedPruningCheckFailed,
 }: {
   isComposable: boolean;
   isBreaking: boolean;
@@ -76,7 +80,14 @@ const isCheckSuccessful = ({
   hasGraphPruningErrors: boolean;
   clientTrafficCheckSkipped: boolean;
   hasProposalMatchError: boolean;
+  isLinkedTrafficCheckFailed?: boolean;
+  isLinkedPruningCheckFailed?: boolean;
 }) => {
+  // if a subgraph is linked to another subgraph, then the status of the check depends on the traffic and pruning check of the linked subgraph
+  if (isLinkedTrafficCheckFailed || isLinkedPruningCheckFailed) {
+    return false;
+  }
+
   return (
     isComposable &&
     // If no breaking changes found

cli/src/commands/subgraph/commands/link.ts

@@ -0,0 +1,62 @@
+import { EnumStatusCode } from '@wundergraph/cosmo-connect/dist/common/common_pb';
+import { Command, program } from 'commander';
+import ora from 'ora';
+import pc from 'picocolors';
+import { getBaseHeaders } from '../../../core/config.js';
+import { BaseCommandOptions } from '../../../core/types/types.js';
+
+export default (opts: BaseCommandOptions) => {
+  const command = new Command('link');
+  command.description(
+    'Links a subgraph to another subgraph on the control plane. When performing schema checks on the source subgraph, traffic and pruning checks will also be performed on the target subgraph. This is useful for verifying the impact of the schema changes before they are propagated to the next environment.',
+  );
+  command.argument('<source-subgraph-name>', 'The name of the subgraph to link.');
+  command.option('-n, --namespace <string>', 'The namespace of the source subgraph.', 'default');
+  command.requiredOption(
+    '-t, --target-subgraph <string>',
+    'The name of the subgraph to link to. Format: <namespace>/<subgraph-name>',
+  );
+
+  command.action(async (name, options) => {
+    // Split on all slashes, take first as namespace, join rest as subgraph name
+    const [targetNamespace, ...rest] = options.targetSubgraph.split('/');
+    if (!targetNamespace || rest.length === 0) {
+      program.error('Target subgraph must be in the format <namespace>/<subgraph-name>');
+    }
+
+    const targetSubgraphName = rest.join('/');
+
+    // Prevent self-linking
+    if (options.namespace === targetNamespace && name === targetSubgraphName) {
+      program.error('The source and target subgraphs cannot be the same subgraphs.');
+    }
+
+    const spinner = ora(`The subgraph "${name}" is being linked to "${targetSubgraphName}"...`).start();
+
+    const resp = await opts.client.platform.linkSubgraph(
+      {
+        sourceSubgraphName: name,
+        sourceSubgraphNamespace: options.namespace,
+        targetSubgraphName,
+        targetSubgraphNamespace: targetNamespace,
+      },
+      {
+        headers: getBaseHeaders(),
+      },
+    );
+
+    if (resp.response?.code === EnumStatusCode.OK) {
+      spinner.succeed('Subgraph was linked successfully.');
+    } else {
+      spinner.fail('Failed to link subgraph.');
+      if (resp.response?.details) {
+        console.log(pc.red(pc.bold(resp.response?.details)));
+      }
+      process.exitCode = 1;
+      // eslint-disable-next-line no-useless-return
+      return;
+    }
+  });
+
+  return command;
+};

cli/src/commands/subgraph/commands/unlink.ts

@@ -0,0 +1,41 @@
+import { EnumStatusCode } from '@wundergraph/cosmo-connect/dist/common/common_pb';
+import { Command } from 'commander';
+import ora from 'ora';
+import pc from 'picocolors';
+import { getBaseHeaders } from '../../../core/config.js';
+import { BaseCommandOptions } from '../../../core/types/types.js';
+
+export default (opts: BaseCommandOptions) => {
+  const command = new Command('unlink');
+  command.description('Unlinks a subgraph from another subgraph on the control plane.');
+  command.argument('<source-subgraph-name>', 'The name of the subgraph to unlink.');
+  command.option('-n, --namespace <string>', 'The namespace of the source subgraph.', 'default');
+
+  command.action(async (name, options) => {
+    const spinner = ora(`The subgraph "${name}" is being unlinked...`).start();
+
+    const resp = await opts.client.platform.unlinkSubgraph(
+      {
+        sourceSubgraphName: name,
+        sourceSubgraphNamespace: options.namespace,
+      },
+      {
+        headers: getBaseHeaders(),
+      },
+    );
+
+    if (resp.response?.code === EnumStatusCode.OK) {
+      spinner.succeed('Subgraph was unlinked successfully.');
+    } else {
+      spinner.fail('Failed to unlink subgraph.');
+      if (resp.response?.details) {
+        console.log(pc.red(pc.bold(resp.response?.details)));
+      }
+      process.exitCode = 1;
+      // eslint-disable-next-line no-useless-return
+      return;
+    }
+  });
+
+  return command;
+};

cli/src/commands/subgraph/index.ts

@@ -11,6 +11,8 @@ import ListSubgraphs from './commands/list.js';
 import IntrospectSubgraph from './commands/introspect.js';
 import MoveSubgraph from './commands/move.js';
 import FetchSubgraph from './commands/fetch.js';
+import LinkSubgraph from './commands/link.js';
+import UnlinkSubgraph from './commands/unlink.js';
 
 export default (opts: BaseCommandOptions) => {
   const command = new Command('subgraph');
@@ -25,6 +27,8 @@ export default (opts: BaseCommandOptions) => {
   command.addCommand(IntrospectSubgraph(opts));
   command.addCommand(MoveSubgraph(opts));
   command.addCommand(FetchSubgraph(opts));
+  command.addCommand(LinkSubgraph(opts));
+  command.addCommand(UnlinkSubgraph(opts));
 
   command.hook('preAction', async (thisCmd) => {
     await checkAuth();

cli/src/handle-check-result.ts

@@ -228,6 +228,21 @@ export const handleCheckResult = (resp: CheckSubgraphSchemaResponse) => {
         console.log(graphPruningIssuesTable.toString());
       }
 
+      if (resp.isLinkedTrafficCheckFailed || resp.isLinkedPruningCheckFailed) {
+        finalStatement += success
+          ? `\n\n But this schema change has been linked to a target subgraph and the target subgraph check has failed.`
+          : `\n\n This schema change has been linked to a target subgraph and the target subgraph check has failed.`;
+
+        if (resp.isLinkedTrafficCheckFailed) {
+          finalStatement += `\n\n The target subgraph check has failed because of client traffic issues.`;
+        }
+
+        if (resp.isLinkedPruningCheckFailed) {
+          finalStatement += `\n\n The target subgraph check has failed because of graph pruning issues.`;
+        }
+        success = false;
+      }
+
       if (success) {
         console.log(
           '\n' +

cli/src/handle-proposal-result.ts

@@ -236,6 +236,21 @@ export const handleProposalResult = (
     console.log(graphPruningIssuesTable.toString());
   }
 
+  if (resp.isLinkedTrafficCheckFailed || resp.isLinkedPruningCheckFailed) {
+    finalStatement += success
+      ? `\n\n But this schema change has been linked to a target subgraph and the target subgraph check has failed.`
+      : `\n\n This schema change has been linked to a target subgraph and the target subgraph check has failed.`;
+
+    if (resp.isLinkedTrafficCheckFailed) {
+      finalStatement += `\n\n The target subgraph check has failed because of client traffic issues.`;
+    }
+
+    if (resp.isLinkedPruningCheckFailed) {
+      finalStatement += `\n\n The target subgraph check has failed because of graph pruning issues.`;
+    }
+    success = false;
+  }
+
   if (success) {
     console.log(
       '\n' +