fix(security): sanitize workspace name before YAML interpolation

platform/internal/handlers/template_import.go

@@ -54,8 +54,24 @@ func generateDefaultConfig(name string, files map[string]string) string {
 		}
 	}
 
+	// Sanitize: emit the name as a YAML double-quoted scalar so any
+	// characters that would break out of the scalar (newline, backslash,
+	// double quote) are escaped instead of injecting new mapping keys.
+	// #221 attack surface: an attacker-controlled name like
+	// "x\nmodel: malicious" would otherwise be interpreted by yaml.Unmarshal
+	// as two separate keys. Double-quoting neutralises every known vector:
+	// \n / \r / \t / \" / \\ are all valid YAML escape sequences inside
+	// a double-quoted scalar.
+	escaped := strings.NewReplacer(
+		`\`, `\\`,
+		`"`, `\"`,
+		"\n", `\n`,
+		"\r", `\r`,
+		"\t", `\t`,
+	).Replace(name)
+
 	var cfg strings.Builder
-	cfg.WriteString("name: " + name + "\n")
+	cfg.WriteString(`name: "` + escaped + `"` + "\n")
 	cfg.WriteString("description: Imported agent\n")
 	cfg.WriteString("version: 1.0.0\ntier: 1\n")
 	cfg.WriteString("model: anthropic:claude-haiku-4-5-20251001\n")

platform/internal/handlers/template_import_test.go

@@ -13,6 +13,7 @@ import (
 	"testing"
 
 	"github.com/DATA-DOG/go-sqlmock"
+	"gopkg.in/yaml.v3"
 	"github.com/gin-gonic/gin"
 )
 
@@ -56,8 +57,9 @@ func TestGenerateDefaultConfig_WithFiles(t *testing.T) {
 
 	cfg := generateDefaultConfig("Test Agent", files)
 
-	if !strings.Contains(cfg, "name: Test Agent") {
-		t.Error("config should contain agent name")
+	// Name is emitted as a double-quoted scalar (#221 sanitizer).
+	if !strings.Contains(cfg, `name: "Test Agent"`) {
+		t.Errorf("config should contain quoted agent name, got:\n%s", cfg)
 	}
 	if !strings.Contains(cfg, "tier: 1") {
 		t.Error("config should default to tier 1")
@@ -85,15 +87,78 @@ func TestGenerateDefaultConfig_Empty(t *testing.T) {
 
 	cfg := generateDefaultConfig("Empty Agent", files)
 
-	if !strings.Contains(cfg, "name: Empty Agent") {
-		t.Error("config should contain agent name")
+	if !strings.Contains(cfg, `name: "Empty Agent"`) {
+		t.Errorf("config should contain quoted agent name, got:\n%s", cfg)
 	}
 	// Should fallback to default prompt file
 	if !strings.Contains(cfg, "system-prompt.md") {
 		t.Error("config should include default system-prompt.md")
 	}
 }
 
+// TestGenerateDefaultConfig_YAMLInjection verifies that a crafted workspace
+// name cannot inject arbitrary YAML keys into the generated config. Regression
+// test for issue #221.
+//
+// Structural assertion: parse the output as YAML and verify the `name` scalar
+// contains the full literal attacker input AND no banned top-level keys slipped
+// in. Substring-based checks fail because escaped \n still contains the
+// attacker's key text as a byte fragment.
+func TestGenerateDefaultConfig_YAMLInjection(t *testing.T) {
+	adversarialCases := []struct {
+		desc       string
+		name       string
+		bannedKeys []string // top-level YAML keys that must NOT appear
+	}{
+		{
+			desc:       "newline followed by new key",
+			name:       "legit-agent\nmodel: malicious:model",
+			bannedKeys: []string{}, // `model` is a legitimate default key too, test via name-scalar integrity
+		},
+		{
+			desc:       "CRLF injection",
+			name:       "legit-agent\r\nmalicious_key: value",
+			bannedKeys: []string{"malicious_key"},
+		},
+		{
+			desc:       "multiple newlines with multiple keys",
+			name:       "x\nfoo: bar\nbaz: qux",
+			bannedKeys: []string{"foo", "baz"},
+		},
+		{
+			desc:       "double-quote escape attempt",
+			name:       `"; evil_key: pwned; #`,
+			bannedKeys: []string{"evil_key"},
+		},
+	}
+
+	for _, tc := range adversarialCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			cfg := generateDefaultConfig(tc.name, map[string]string{})
+			var parsed map[string]interface{}
+			if err := yaml.Unmarshal([]byte(cfg), &parsed); err != nil {
+				t.Fatalf("sanitized config does not parse as YAML: %v\n--- config ---\n%s", err, cfg)
+			}
+			// 1. name key must equal the original attacker input (escaping preserved payload)
+			if got, _ := parsed["name"].(string); got != tc.name {
+				t.Errorf("name scalar mismatch:\n  got:  %q\n  want: %q", got, tc.name)
+			}
+			// 2. No banned top-level keys injected
+			for _, k := range tc.bannedKeys {
+				if _, exists := parsed[k]; exists {
+					t.Errorf("YAML injection: banned key %q leaked to parsed config", k)
+				}
+			}
+			// 3. Legitimate default keys still present — escaping didn't corrupt the rest
+			for _, expected := range []string{"name", "description", "version", "tier", "model"} {
+				if _, exists := parsed[expected]; !exists {
+					t.Errorf("missing legitimate key %q in parsed config", expected)
+				}
+			}
+		})
+	}
+}
+
 // ==================== writeFiles ====================
 
 func TestWriteFiles_Success(t *testing.T) {