feat: support disabling bundled mcp servers

scripts/codex/merge-mcp-config.js

@@ -19,6 +19,7 @@
 
 const fs = require('fs');
 const path = require('path');
+const { parseDisabledMcpServers } = require('../lib/mcp-config');
 
 let TOML;
 try {
@@ -210,6 +211,7 @@ function main() {
   const configPath = args.find(a => !a.startsWith('-'));
   const dryRun = args.includes('--dry-run');
   const updateMcp = args.includes('--update-mcp');
+  const disabledServers = new Set(parseDisabledMcpServers(process.env.ECC_DISABLED_MCPS));
 
   if (!configPath) {
     console.error('Usage: merge-mcp-config.js <config.toml> [--dry-run] [--update-mcp]');
@@ -222,6 +224,9 @@ function main() {
   }
 
   log(`Package manager: ${PM_NAME} (exec: ${PM_EXEC})`);
+  if (disabledServers.size > 0) {
+    log(`Disabled via ECC_DISABLED_MCPS: ${[...disabledServers].join(', ')}`);
+  }
 
   let raw = fs.readFileSync(configPath, 'utf8');
   let parsed;
@@ -249,6 +254,18 @@ function main() {
     const finalEntry = resolvedEntry || urlEntry;
     const resolvedLabel = hasCanonical ? name : legacyName || name;
 
+    if (disabledServers.has(name)) {
+      if (finalEntry) {
+        toRemoveLog.push(`mcp_servers.${resolvedLabel} (disabled)`);
+        raw = removeServerFromText(raw, resolvedLabel, existing);
+        if (resolvedLabel !== name) {
+          raw = removeServerFromText(raw, name, existing);
+        }
+      }
+      log(`  [skip] mcp_servers.${name} (disabled)`);
+      continue;
+    }
+
     if (finalEntry) {
       if (updateMcp) {
         // --update-mcp: remove existing section (and legacy alias), will re-add below
@@ -278,7 +295,9 @@ function main() {
     }
   }
 
-  if (toAppend.length === 0) {
+  const hasRemovals = toRemoveLog.length > 0;
+
+  if (toAppend.length === 0 && !hasRemovals) {
     log('All ECC MCP servers already present. Nothing to do.');
     return;
   }
@@ -297,14 +316,19 @@ function main() {
 
   // Write: for add-only, append to preserve existing content byte-for-byte.
   // For --update-mcp, we modified `raw` above, so write the full file + appended sections.
-  if (updateMcp) {
+  if (updateMcp || hasRemovals) {
     for (const label of toRemoveLog) log(`  [update] ${label}`);
     const cleaned = raw.replace(/\n+$/, '\n');
-    fs.writeFileSync(configPath, cleaned + appendText, 'utf8');
+    fs.writeFileSync(configPath, cleaned + (toAppend.length > 0 ? appendText : ''), 'utf8');
   } else {
     fs.appendFileSync(configPath, appendText, 'utf8');
   }
 
+  if (hasRemovals && toAppend.length === 0) {
+    log(`Done. Removed ${toRemoveLog.length} disabled server(s).`);
+    return;
+  }
+
   log(`Done. ${toAppend.length} server(s) ${updateMcp ? 'updated' : 'added'}.`);
 }
 

scripts/lib/install/apply.js

@@ -4,6 +4,7 @@ const fs = require('fs');
 const path = require('path');
 
 const { writeInstallState } = require('../install-state');
+const { filterMcpConfig, parseDisabledMcpServers } = require('../mcp-config');
 
 function readJsonObject(filePath, label) {
   let parsed;
@@ -124,6 +125,49 @@ function findHooksSourcePath(plan, hooksDestinationPath) {
   return operation ? operation.sourcePath : null;
 }
 
+function isMcpConfigPath(filePath) {
+  const basename = path.basename(String(filePath || ''));
+  return basename === '.mcp.json' || basename === 'mcp.json';
+}
+
+function buildFilteredMcpWrites(plan) {
+  const disabledServers = parseDisabledMcpServers(process.env.ECC_DISABLED_MCPS);
+  if (disabledServers.length === 0) {
+    return [];
+  }
+
+  const writes = [];
+
+  for (const operation of plan.operations) {
+    if (!isMcpConfigPath(operation.destinationPath) || !operation.sourcePath || !fs.existsSync(operation.sourcePath)) {
+      continue;
+    }
+
+    let sourceConfig;
+    try {
+      sourceConfig = readJsonObject(operation.sourcePath, 'MCP config');
+    } catch {
+      continue;
+    }
+
+    if (!sourceConfig.mcpServers || typeof sourceConfig.mcpServers !== 'object' || Array.isArray(sourceConfig.mcpServers)) {
+      continue;
+    }
+
+    const filtered = filterMcpConfig(sourceConfig, disabledServers);
+    if (filtered.removed.length === 0) {
+      continue;
+    }
+
+    writes.push({
+      destinationPath: operation.destinationPath,
+      filteredConfig: filtered.config,
+    });
+  }
+
+  return writes;
+}
+
 function buildMergedSettings(plan) {
   if (!plan.adapter || plan.adapter.target !== 'claude') {
     return null;
@@ -177,6 +221,7 @@ function buildMergedSettings(plan) {
 
 function applyInstallPlan(plan) {
   const mergedSettingsPlan = buildMergedSettings(plan);
+  const filteredMcpWrites = buildFilteredMcpWrites(plan);
 
   for (const operation of plan.operations) {
     fs.mkdirSync(path.dirname(operation.destinationPath), { recursive: true });
@@ -198,6 +243,15 @@ function applyInstallPlan(plan) {
     );
   }
 
+  for (const writePlan of filteredMcpWrites) {
+    fs.mkdirSync(path.dirname(writePlan.destinationPath), { recursive: true });
+    fs.writeFileSync(
+      writePlan.destinationPath,
+      JSON.stringify(writePlan.filteredConfig, null, 2) + '\n',
+      'utf8'
+    );
+  }
+
   writeInstallState(plan.installStatePath, plan.statePreview);
 
   return {

scripts/lib/mcp-config.js

@@ -0,0 +1,56 @@
+'use strict';
+
+function parseDisabledMcpServers(value) {
+  return [...new Set(
+    String(value || '')
+      .split(',')
+      .map((entry) => entry.trim())
+      .filter(Boolean)
+  )];
+}
+
+function filterMcpConfig(config, disabledServerNames = []) {
+  if (!config || typeof config !== 'object' || Array.isArray(config)) {
+    throw new Error('MCP config must be a JSON object');
+  }
+
+  const servers = config.mcpServers;
+  if (!servers || typeof servers !== 'object' || Array.isArray(servers)) {
+    throw new Error('MCP config must include an mcpServers object');
+  }
+
+  const disabled = new Set(parseDisabledMcpServers(disabledServerNames));
+  if (disabled.size === 0) {
+    return {
+      config: {
+        ...config,
+        mcpServers: { ...servers },
+      },
+      removed: [],
+    };
+  }
+
+  const nextServers = {};
+  const removed = [];
+
+  for (const [name, serverConfig] of Object.entries(servers)) {
+    if (disabled.has(name)) {
+      removed.push(name);
+      continue;
+    }
+    nextServers[name] = serverConfig;
+  }
+
+  return {
+    config: {
+      ...config,
+      mcpServers: nextServers,
+    },
+    removed,
+  };
+}
+
+module.exports = {
+  filterMcpConfig,
+  parseDisabledMcpServers,
+};