workspace-server/internal/handlers/runtime_registry.go

@@ -86,6 +86,40 @@ var fallbackRuntimes = map[string]struct{}{
 	"mock": {},
 }
 
+// stripJSON5Comments removes // single-line comments from JSON5-formatted
+// data. The Integration Tester appends "// Triggered by <job>" to
+// manifest.json after cloning, which causes json.Unmarshal to fail with
+// "invalid character '/'". This strips trailing and mid-file comments
+// before parsing so Go's strict JSON parser accepts JSON5 files.
+//
+// Handles:
+//   - Standalone comment lines:    // comment
+//   - Trailing comments:          "key": "value", // comment
+//   - Comments inside strings are NOT touched ("http://example.com")
+func stripJSON5Comments(data []byte) []byte {
+	var result []byte
+	inString := false
+	i := 0
+	for i < len(data) {
+		if data[i] == '"' && (i == 0 || data[i-1] != '\\') {
+			inString = !inString
+			result = append(result, data[i])
+			i++
+			continue
+		}
+		if !inString && i+1 < len(data) && data[i] == '/' && data[i+1] == '/' {
+			// Skip to end of line
+			for i < len(data) && data[i] != '\n' {
+				i++
+			}
+			continue
+		}
+		result = append(result, data[i])
+		i++
+	}
+	return result
+}
+
 // loadRuntimesFromManifest builds the runtime allowlist from
 // manifest.json. Each workspace_templates[].name is normalized to its
 // base runtime identifier (strips the `-default` suffix templates
@@ -101,6 +135,9 @@ func loadRuntimesFromManifest(path string) (map[string]struct{}, error) {
 	if err != nil {
 		return nil, err
 	}
+	// Strip JSON5 // comments before parsing. The Integration Tester
+	// appends "// Triggered by <job>" to manifest.json after cloning.
+	data = stripJSON5Comments(data)
 	var m manifestFile
 	if err := json.Unmarshal(data, &m); err != nil {
 		return nil, err

workspace-server/internal/handlers/runtime_registry_test.go

@@ -8,6 +8,7 @@ package handlers
 //      fallback (tested at the initKnownRuntimes level via integration).
 
 import (
+	"encoding/json"
 	"os"
 	"path/filepath"
 	"testing"
@@ -111,3 +112,133 @@ func keys(m map[string]struct{}) []string {
 	}
 	return out
 }
+
+// ── stripJSON5Comments tests ─────────────────────────────────────────────────
+
+func TestStripJSON5Comments_Standalone(t *testing.T) {
+	// Whitespace before the // is preserved; only the // and its text are removed.
+	// The result is still valid JSON.
+	input := "{\n\t// This is a comment\n\t\"workspace_templates\": []\n}"
+	got := string(stripJSON5Comments([]byte(input)))
+	// Stripping should produce valid JSON: try parsing it
+	var m manifestFile
+	if err := json.Unmarshal([]byte(got), &m); err != nil {
+		t.Errorf("output is not valid JSON: %v\ngot: %q", err, got)
+	}
+	if m.WorkspaceTemplates == nil {
+		t.Error("WorkspaceTemplates field should be present after parsing")
+	}
+}
+
+func TestStripJSON5Comments_Trailing(t *testing.T) {
+	input := `{"key": "value"} // trailing comment`
+	got := string(stripJSON5Comments([]byte(input)))
+	want := `{"key": "value"} `
+	if got != want {
+		t.Errorf("trailing comment:\ngot:  %q\nwant: %q", got, want)
+	}
+}
+
+func TestStripJSON5Comments_URLsPreserved(t *testing.T) {
+	// URLs with // in them must NOT be stripped
+	input := `{"url": "https://example.com/path"}`
+	got := string(stripJSON5Comments([]byte(input)))
+	if got != input {
+		t.Errorf("URL stripped: got %q, want %q", got, input)
+	}
+}
+
+func TestStripJSON5Comments_InlineComment(t *testing.T) {
+	// Whitespace before // is preserved; only the comment text is removed.
+	// Result must be valid JSON.
+	input := "{\n\t\"workspace_templates\": [] // inline comment\n}"
+	got := string(stripJSON5Comments([]byte(input)))
+	var m manifestFile
+	if err := json.Unmarshal([]byte(got), &m); err != nil {
+		t.Errorf("output is not valid JSON: %v\ngot: %q", err, got)
+	}
+}
+
+func TestStripJSON5Comments_IntegrationTesterAppend(t *testing.T) {
+	// Simulates what the Integration Tester does: appends // Triggered by ...
+	// to the end of a valid JSON file.
+	input := `{
+	"workspace_templates": [
+		{"name": "hermes", "repo": "org/hermes"}
+	]
+}
+// Triggered by e2e-test job 12345
+`
+	got := string(stripJSON5Comments([]byte(input)))
+	if got == input {
+		t.Error("Integration Tester comment was NOT stripped")
+	}
+	// After stripping, it should be valid JSON
+	var m manifestFile
+	if err := json.Unmarshal([]byte(got), &m); err != nil {
+		t.Errorf("stripped content is not valid JSON: %v\ngot: %q", err, got)
+	}
+	if len(m.WorkspaceTemplates) != 1 || m.WorkspaceTemplates[0].Name != "hermes" {
+		t.Errorf("workspace_templates not parsed: %+v", m.WorkspaceTemplates)
+	}
+}
+
+func TestStripJSON5Comments_NoComments(t *testing.T) {
+	input := `{"workspace_templates": [{"name": "hermes"}]}`
+	got := string(stripJSON5Comments([]byte(input)))
+	if got != input {
+		t.Errorf("unmodified JSON changed: got %q", got)
+	}
+}
+
+// ── loadRuntimesFromManifest with JSON5 comments ─────────────────────────────
+
+func TestLoadRuntimesFromManifest_WithJSON5TrailingComment(t *testing.T) {
+	// Regression: Integration Tester appends "// Triggered by ..." to manifest.json
+	// after cloning. Before the fix, this caused json.Unmarshal to fail with
+	// "invalid character '/'". After the fix, the comment is stripped first.
+	dir := t.TempDir()
+	path := filepath.Join(dir, "manifest.json")
+	manifest := `{
+		"workspace_templates": [
+			{"name": "hermes", "repo": "org/hermes"},
+			{"name": "claude-code-default", "repo": "org/cc"}
+		]
+	}
+	// Triggered by e2e-test job
+	`
+	if err := os.WriteFile(path, []byte(manifest), 0600); err != nil {
+		t.Fatalf("write: %v", err)
+	}
+	got, err := loadRuntimesFromManifest(path)
+	if err != nil {
+		t.Fatalf("loadRuntimesFromManifest with trailing comment: %v", err)
+	}
+	for _, must := range []string{"hermes", "claude-code"} {
+		if _, ok := got[must]; !ok {
+			t.Errorf("expected runtime %q in result: %v", must, keys(got))
+		}
+	}
+}
+
+func TestLoadRuntimesFromManifest_WithInlineJSON5Comment(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "manifest.json")
+	// JSON5 with inline comment
+	manifest := `{
+		// runtime templates
+		"workspace_templates": [
+			{"name": "langgraph", "repo": "org/lg"} // the default
+		]
+	}`
+	if err := os.WriteFile(path, []byte(manifest), 0600); err != nil {
+		t.Fatalf("write: %v", err)
+	}
+	got, err := loadRuntimesFromManifest(path)
+	if err != nil {
+		t.Fatalf("loadRuntimesFromManifest with inline comment: %v", err)
+	}
+	if _, ok := got["langgraph"]; !ok {
+		t.Errorf("expected langgraph in result: %v", keys(got))
+	}
+}