diff --git a/.gitignore b/.gitignore
index 0447fdfd..699fc754 100644
--- a/.gitignore
+++ b/.gitignore
@@ -49,3 +49,9 @@ _bmad-output/*
 # macOS
 .DS_Store
 ._*
+
+# Opencode
+.beads/
+.opencode/
+.cli-proxy-api/
+.venv/
diff --git a/cmd/server/main.go b/cmd/server/main.go
index e12e5261..8bc41c78 100644
--- a/cmd/server/main.go
+++ b/cmd/server/main.go
@@ -70,6 +70,7 @@ func main() {
 	var kimiLogin bool
 	var projectID string
 	var vertexImport string
+	var vertexImportPrefix string
 	var configPath string
 	var password string
 	var tuiMode bool
@@ -91,6 +92,7 @@ func main() {
 	flag.StringVar(&projectID, "project_id", "", "Project ID (Gemini only, not required)")
 	flag.StringVar(&configPath, "config", DefaultConfigPath, "Configure File Path")
 	flag.StringVar(&vertexImport, "vertex-import", "", "Import Vertex service account key JSON file")
+	flag.StringVar(&vertexImportPrefix, "vertex-import-prefix", "", "Prefix for Vertex model namespacing (use with -vertex-import)")
 	flag.StringVar(&password, "password", "", "")
 	flag.BoolVar(&tuiMode, "tui", false, "Start with terminal management UI")
 	flag.BoolVar(&standalone, "standalone", false, "In TUI mode, start an embedded local server")
@@ -462,7 +464,7 @@ func main() {
 
 	if vertexImport != "" {
 		// Handle Vertex service account import
-		cmd.DoVertexImport(cfg, vertexImport)
+		cmd.DoVertexImport(cfg, vertexImport, vertexImportPrefix)
 	} else if login {
 		// Handle Google/Gemini login
 		cmd.DoLogin(cfg, projectID, options)
diff --git a/internal/auth/vertex/vertex_credentials.go b/internal/auth/vertex/vertex_credentials.go
index 4853d340..9f830994 100644
--- a/internal/auth/vertex/vertex_credentials.go
+++ b/internal/auth/vertex/vertex_credentials.go
@@ -30,6 +30,10 @@ type VertexCredentialStorage struct {
 
 	// Type is the provider identifier stored alongside credentials. Always "vertex".
 	Type string `json:"type"`
+
+	// Prefix optionally namespaces models for this credential (e.g., "teamA").
+	// This results in model names like "teamA/gemini-2.0-flash".
+	Prefix string `json:"prefix,omitempty"`
 }
 
 // SaveTokenToFile writes the credential payload to the given file path in JSON format.
diff --git a/internal/cmd/vertex_import.go b/internal/cmd/vertex_import.go
index 32d782d8..4aa0d74b 100644
--- a/internal/cmd/vertex_import.go
+++ b/internal/cmd/vertex_import.go
@@ -20,7 +20,7 @@ import (
 // DoVertexImport imports a Google Cloud service account key JSON and persists
 // it as a "vertex" provider credential. The file content is embedded in the auth
 // file to allow portable deployment across stores.
-func DoVertexImport(cfg *config.Config, keyPath string) {
+func DoVertexImport(cfg *config.Config, keyPath string, prefix string) {
 	if cfg == nil {
 		cfg = &config.Config{}
 	}
@@ -62,13 +62,28 @@ func DoVertexImport(cfg *config.Config, keyPath string) {
 	// Default location if not provided by user. Can be edited in the saved file later.
 	location := "us-central1"
 
-	fileName := fmt.Sprintf("vertex-%s.json", sanitizeFilePart(projectID))
+	// Normalize and validate prefix: must be a single segment (no "/" allowed).
+	prefix = strings.TrimSpace(prefix)
+	prefix = strings.Trim(prefix, "/")
+	if prefix != "" && strings.Contains(prefix, "/") {
+		log.Errorf("vertex-import: prefix must be a single segment (no '/' allowed): %q", prefix)
+		return
+	}
+
+	// Include prefix in filename so importing the same project with different
+	// prefixes creates separate credential files instead of overwriting.
+	baseName := sanitizeFilePart(projectID)
+	if prefix != "" {
+		baseName = sanitizeFilePart(prefix) + "-" + baseName
+	}
+	fileName := fmt.Sprintf("vertex-%s.json", baseName)
 	// Build auth record
 	storage := &vertex.VertexCredentialStorage{
 		ServiceAccount: sa,
 		ProjectID:      projectID,
 		Email:          email,
 		Location:       location,
+		Prefix:         prefix,
 	}
 	metadata := map[string]any{
 		"service_account": sa,
@@ -76,6 +91,7 @@ func DoVertexImport(cfg *config.Config, keyPath string) {
 		"email":           email,
 		"location":        location,
 		"type":            "vertex",
+		"prefix":          prefix,
 		"label":           labelForVertex(projectID, email),
 	}
 	record := &coreauth.Auth{