diff --git a/CHANGELOG.md b/CHANGELOG.md
index f47e609a..34fd4fab 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## [Unreleased]
+
+### Fixed
+
+- Fixed `mobilebuildmcp debugging attach --pid` failing with "Mutually exclusive parameters provided: bundleId, pid" when the project's session defaults set `bundleId`. An explicit `pid` now drops the configured `bundleId` on the CLI, as it already did over MCP ([#551](https://github.com/getsentry/MobileBuildMCP/issues/551)).
+
 ## [2.7.1]
 
 ### Changed
diff --git a/src/cli/__tests__/session-defaults.test.ts b/src/cli/__tests__/session-defaults.test.ts
index f30f298c..e23c1913 100644
--- a/src/cli/__tests__/session-defaults.test.ts
+++ b/src/cli/__tests__/session-defaults.test.ts
@@ -73,6 +73,39 @@ describe('CLI session defaults', () => {
     });
   });
 
+  it('drops a configured bundleId when the user attaches by pid', () => {
+    const merged = mergeCliSessionDefaults({
+      defaults: {
+        bundleId: 'com.example.App',
+        simulatorId: 'SIM-1',
+      },
+      explicitArgs: {
+        pid: 4242,
+      },
+    });
+
+    expect(merged).toEqual({
+      simulatorId: 'SIM-1',
+      pid: 4242,
+    });
+  });
+
+  it('drops a configured bundleId when JSON args pass pid with a null bundleId', () => {
+    const merged = mergeCliSessionDefaults({
+      defaults: {
+        bundleId: 'com.example.App',
+      },
+      explicitArgs: {
+        pid: 4242,
+        bundleId: null,
+      },
+    });
+
+    expect(merged).toEqual({
+      pid: 4242,
+    });
+  });
+
   it('prefers simulatorId when both simulator defaults come only from config', () => {
     const merged = mergeCliSessionDefaults({
       defaults: {
diff --git a/src/cli/session-defaults.ts b/src/cli/session-defaults.ts
index 0097a630..0f5a8a25 100644
--- a/src/cli/session-defaults.ts
+++ b/src/cli/session-defaults.ts
@@ -5,11 +5,15 @@ import type { SessionDefaults } from '../utils/session-store.ts';
 import {
   mergeSessionDefaultArgs,
   pickSessionDefaultsForKeys,
+  type ExclusiveParameterGroup,
 } from '../utils/session-default-args.ts';
 
-const CLI_SESSION_DEFAULT_EXCLUSIVE_PAIRS: (keyof SessionDefaults)[][] = [
+// Mirrors the exclusive pairs the tool handlers declare: an explicit value for one key drops the
+// configured default for the other, so a merged default never collides with an explicit argument.
+const CLI_SESSION_DEFAULT_EXCLUSIVE_PAIRS: readonly ExclusiveParameterGroup[] = [
   ['projectPath', 'workspacePath'],
   ['simulatorId', 'simulatorName'],
+  ['bundleId', 'pid'],
 ];
 
 export function resolveCliSessionDefaults(opts: {