diff --git a/internal/claude/claude.go b/internal/claude/claude.go
index 8d972e5..195810b 100644
--- a/internal/claude/claude.go
+++ b/internal/claude/claude.go
@@ -55,6 +55,18 @@ func BuildEnv(configDir string) []string {
 	return env
 }
 
+// UnsetEnv removes a named environment variable from an env slice. If the key
+// is not present, the slice is returned unchanged.
+func UnsetEnv(env []string, key string) []string {
+	prefix := key + "="
+	for i, e := range env {
+		if len(e) >= len(prefix) && e[:len(prefix)] == prefix {
+			return append(env[:i], env[i+1:]...)
+		}
+	}
+	return env
+}
+
 // RunDirect executes the claude binary as a child process without a PTY
 // wrapper, connecting stdin/stdout/stderr directly. It returns the child's exit
 // code and any non-exit error. This is used by subcommands like "auth login"
diff --git a/internal/claude/claude_test.go b/internal/claude/claude_test.go
index 8e75bd2..3fdd324 100644
--- a/internal/claude/claude_test.go
+++ b/internal/claude/claude_test.go
@@ -102,6 +102,30 @@ func TestRunDirect_BinaryNotFound(t *testing.T) {
 	assert.Error(t, err)
 }
 
+func TestUnsetEnv_RemovesKey(t *testing.T) {
+	env := []string{"FOO=bar", "CLAUDE_CODE_USE_BEDROCK=1", "BAZ=qux"}
+	result := UnsetEnv(env, "CLAUDE_CODE_USE_BEDROCK")
+	assert.Equal(t, []string{"FOO=bar", "BAZ=qux"}, result)
+}
+
+func TestUnsetEnv_KeyNotPresent(t *testing.T) {
+	env := []string{"FOO=bar", "BAZ=qux"}
+	result := UnsetEnv(env, "CLAUDE_CODE_USE_BEDROCK")
+	assert.Equal(t, []string{"FOO=bar", "BAZ=qux"}, result)
+}
+
+func TestUnsetEnv_EmptyEnv(t *testing.T) {
+	result := UnsetEnv([]string{}, "FOO")
+	assert.Empty(t, result)
+}
+
+func TestUnsetEnv_DoesNotMatchPrefix(t *testing.T) {
+	env := []string{"CLAUDE_CODE_USE_BEDROCK_EXTRA=1", "FOO=bar"}
+	result := UnsetEnv(env, "CLAUDE_CODE_USE_BEDROCK")
+	// Should not remove CLAUDE_CODE_USE_BEDROCK_EXTRA since it's a different key
+	assert.Equal(t, []string{"CLAUDE_CODE_USE_BEDROCK_EXTRA=1", "FOO=bar"}, result)
+}
+
 func TestBuildEnv_PreservesOtherVars(t *testing.T) {
 	t.Setenv("MY_TEST_VAR_12345", "hello")
 
diff --git a/internal/cli/passthrough.go b/internal/cli/passthrough.go
index d7b9e72..048f45f 100644
--- a/internal/cli/passthrough.go
+++ b/internal/cli/passthrough.go
@@ -56,6 +56,14 @@ func runPassthrough(cmd *cobra.Command, _ []string) error {
 	cfg := p.LoadConfig()
 
 	env := claude.BuildEnv(p.ConfigDir)
+
+	// When the profile has SSO credentials, strip provider flags that would
+	// override the auth method. The user's intent is to use the Anthropic API.
+	if authStatus == "keychain" || authStatus == "file" {
+		env = claude.UnsetEnv(env, "CLAUDE_CODE_USE_BEDROCK")
+		env = claude.UnsetEnv(env, "CLAUDE_CODE_USE_VERTEX")
+	}
+
 	env = setEnv(env, "CLAUDE_PROFILE_NAME", name)
 	env = setEnv(env, "CLAUDE_PROFILE_AUTH", authStatus)
 	env = setEnv(env, "CLAUDE_PROFILE_SUB", subType)
@@ -113,7 +121,13 @@ func extractClaudeArgs() []string {
 
 // Version is set at build time via -ldflags (e.g., -ldflags "-X ...cli.Version=1.2.3").
 // Falls back to VCS info embedded by Go, or "dev" if neither is available.
-var Version = buildVersion()
+var Version string
+
+func init() {
+	if Version == "" {
+		Version = buildVersion()
+	}
+}
 
 func buildVersion() string {
 	info, ok := debug.ReadBuildInfo()