fix(security): sanitize body.Name before YAML interpolation in generateDefaultConfig

A crafted workspace name containing a newline (e.g. "x\nmodel: evil")
could inject arbitrary YAML keys into the auto-generated config.yaml.
Strip \n and \r from the name before interpolation. YAML key injection
requires a newline to start a new mapping entry; other characters such
as `:` are safe in unquoted scalar values.

Adds TestGenerateDefaultConfig_YAMLInjection with three adversarial
inputs: bare \n injection, CRLF injection, and multi-key injection.

Closes #221

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

platform/internal/handlers/template_import.go

@@ -54,6 +54,13 @@ func generateDefaultConfig(name string, files map[string]string) string {
 		}
 	}
 
+	// Sanitize: strip newlines and carriage returns to prevent YAML key
+	// injection. A crafted name like "x\nmodel: malicious" would otherwise
+	// break out of the scalar and inject arbitrary YAML keys. Newlines are
+	// the only vector because YAML only starts a new mapping entry on a new
+	// line; other characters such as ":" are safe in unquoted scalar values.
+	name = strings.NewReplacer("\n", "", "\r", "").Replace(name)
+
 	var cfg strings.Builder
 	cfg.WriteString("name: " + name + "\n")
 	cfg.WriteString("description: Imported agent\n")

platform/internal/handlers/template_import_test.go

@@ -94,6 +94,44 @@ func TestGenerateDefaultConfig_Empty(t *testing.T) {
 	}
 }
 
+// TestGenerateDefaultConfig_YAMLInjection verifies that a crafted workspace
+// name containing a newline cannot inject arbitrary YAML keys into the
+// generated config. This is the regression test for issue #221.
+func TestGenerateDefaultConfig_YAMLInjection(t *testing.T) {
+	adversarialCases := []struct {
+		desc        string
+		name        string
+		bannedLines []string // lines that must NOT appear in the output
+	}{
+		{
+			desc:        "newline followed by new key",
+			name:        "legit-agent\nmodel: malicious:model",
+			bannedLines: []string{"model: malicious:model"},
+		},
+		{
+			desc:        "CRLF injection",
+			name:        "legit-agent\r\nmalicious_key: value",
+			bannedLines: []string{"malicious_key: value"},
+		},
+		{
+			desc:        "multiple newlines with multiple keys",
+			name:        "x\nfoo: bar\nbaz: qux",
+			bannedLines: []string{"foo: bar", "baz: qux"},
+		},
+	}
+
+	for _, tc := range adversarialCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			cfg := generateDefaultConfig(tc.name, map[string]string{})
+			for _, banned := range tc.bannedLines {
+				if strings.Contains(cfg, banned) {
+					t.Errorf("YAML injection: output contains injected line %q\nfull config:\n%s", banned, cfg)
+				}
+			}
+		})
+	}
+}
+
 // ==================== writeFiles ====================
 
 func TestWriteFiles_Success(t *testing.T) {