fix: wrap Mermaid output in code fence for GitHub rendering

Author: thegdsks

internal/renderer/mermaid.go

@@ -60,7 +60,8 @@ func truncate(s string, n int) string {
 func WriteMermaid(idx *schema.Index, path string) error {
 	var sb strings.Builder
 
-	sb.WriteString("graph LR\n")
+	// Wrap in markdown code fence so GitHub renders the diagram.
+	sb.WriteString("```mermaid\ngraph LR\n")
 
 	// Collect which languages are actually used by modules.
 	usedLangs := map[string]bool{}
@@ -106,5 +107,6 @@ func WriteMermaid(idx *schema.Index, path string) error {
 		sb.WriteString(fmt.Sprintf("  %s --> %s\n", from, to))
 	}
 
+	sb.WriteString("```\n")
 	return os.WriteFile(path, []byte(sb.String()), 0644)
 }

internal/renderer/mermaid_test.go

@@ -57,7 +57,7 @@ func TestRenderMermaid(t *testing.T) {
 	content := string(data)
 
 	// Must start with graph LR
-	if !strings.HasPrefix(content, "graph LR\n") {
+	if !strings.HasPrefix(content, "```mermaid\ngraph LR\n") {
 		t.Errorf("expected content to start with 'graph LR\\n', got: %q", content[:min(len(content), 20)])
 	}
 
@@ -102,7 +102,7 @@ func TestRenderMermaidEmpty(t *testing.T) {
 	}
 	content := string(data)
 
-	if !strings.HasPrefix(content, "graph LR\n") {
+	if !strings.HasPrefix(content, "```mermaid\ngraph LR\n") {
 		t.Errorf("expected empty diagram to start with 'graph LR\\n', got: %q", content)
 	}
 }

stacklit.json

@@ -1,9 +1,9 @@
 {
   "$schema": "https://stacklit.dev/schema/v1.json",
   "version": "1",
-  "generated_at": "2026-04-10T00:05:04Z",
+  "generated_at": "2026-04-10T00:13:27Z",
   "stacklit_version": "dev",
-  "merkle_hash": "bd0d1090ba4aff650f9a9d9a308b118e7708043445a2cc9cbc202e800378608e",
+  "merkle_hash": "a4375e781070df0cf5d9b49c6b64aa1a902ed9a002d18cc9f0e62544227f4b4a",
   "project": {
     "name": "stacklit",
     "root": ".",
@@ -14,7 +14,7 @@
     "languages": {
       "go": {
         "files": 48,
-        "lines": 5698
+        "lines": 5700
       },
       "java": {
         "files": 1,
@@ -47,7 +47,7 @@
       "cmd/stacklit/main.go"
     ],
     "total_files": 59,
-    "total_lines": 5910
+    "total_lines": 5912
   },
   "modules": {
     "assets": {
@@ -341,7 +341,7 @@
       "purpose": "Output renderers",
       "language": "go",
       "files": 5,
-      "lines": 371,
+      "lines": 373,
       "file_list": [
         "html.go",
         "json.go",
@@ -386,14 +386,14 @@
       ],
       "type_defs": {
         "Architecture": "Pattern string, Summary string",
-        "Hints": "AddFeature string, TestCmd string, EnvVars []string, DoNotTouch []string",
+        "Dependencies": "Edges [][]string, Entrypoints []string, MostDepended []string, Isolated []string",
+        "GitInfo": "HotFiles []HotFile, Recent []string, Stable []string",
         "HotFile": "Path string, Commits90d int",
         "Index": "Schema string, Version string, GeneratedAt string, StacklitVersion string, MerkleHash string, Project Project, Tech Tech, Structure Structure, Modules map[string]ModuleInfo, Dependencies Dependenci...",
-        "LangStats": "Files int, Lines int",
         "ModuleInfo": "Purpose string, Language string, Files int, Lines int, FileList []string, Exports []string, TypeDefs map[string]string, DependsOn []string, DependedBy []string, Activity string",
         "MultiIndex": "Schema string, Version string, Type string, GeneratedAt string, TotalFiles int, TotalLines int, TotalModules int, Repos []RepoSummary",
-        "Project": "Name string, Root string, Type string, Workspaces []string",
         "RepoSummary": "Name string, Path string, PrimaryLanguage string, TotalFiles int, TotalLines int, Modules map[string]ModuleInfo, Frameworks []string, Entrypoints []string",
+        "Structure": "Entrypoints []string, TotalFiles int, TotalLines int, KeyDirectories map[string]string",
         "Tech": "PrimaryLanguage string, Languages map[string]LangStats, Frameworks []string"
       },
       "depended_by": [
@@ -578,15 +578,15 @@
     "hot_files": [
       {
         "path": "internal/engine/engine.go",
-        "commits_90d": 12
+        "commits_90d": 13
       },
       {
         "path": "stacklit.json",
-        "commits_90d": 11
+        "commits_90d": 12
       },
       {
         "path": "stacklit.mmd",
-        "commits_90d": 11
+        "commits_90d": 12
       },
       {
         "path": "assets/template.html",
@@ -602,7 +602,7 @@
       },
       {
         "path": "README.md",
-        "commits_90d": 5
+        "commits_90d": 6
       },
       {
         "path": "go.mod",
@@ -658,28 +658,28 @@
       }
     ],
     "recent": [
+      "npm/README.md",
+      "npm/package.json",
       "README.md",
-      "assets/template.html",
       "demo.gif",
       "demo.tape",
-      "internal/mcp/server.go",
+      "internal/engine/engine.go",
+      "stacklit-og.png",
       "stacklit.json",
       "stacklit.mmd",
-      "npm/README.md",
-      "npm/bin/stacklit.js",
-      "npm/package.json"
+      "assets/template.html"
     ],
     "stable": [
       "LICENSE",
       "action/action.yml",
       "assets/lang-icons.js",
-      "demo.gif",
-      "demo.tape",
       "internal/cli/serve.go",
       "internal/config/config.go",
       "internal/config/config_test.go",
       "internal/detect/envvars.go",
-      "internal/detect/frameworks.go"
+      "internal/detect/frameworks.go",
+      "internal/detect/frameworks_test.go",
+      "internal/git/activity.go"
     ]
   },
   "hints": {

stacklit.mmd

@@ -1,27 +1,28 @@
+```mermaid
 graph LR
   classDef javascript fill:#c9d1d9,color:#0d1117,stroke:#c9d1d9
   classDef java fill:#8b949e,color:#0d1117,stroke:#8b949e
   classDef typescript fill:#c9d1d9,color:#0d1117,stroke:#c9d1d9
   classDef python fill:#b1bac4,color:#0d1117,stroke:#b1bac4
   classDef rust fill:#a5b3bf,color:#0d1117,stroke:#a5b3bf
   classDef go fill:#e6edf3,color:#0d1117,stroke:#e6edf3
-  internal_engine["internal/engine\nCore orchestration engine"]:::go
-  internal_mcp["internal/mcp\nMCP server for AI agents"]:::go
-  internal_monorepo["internal/monorepo\nMonorepo detection"]:::go
-  internal_parser["internal/parser\nSource code parsers"]:::go
-  internal_summary["internal/summary\nAI-powered codebase summaries"]:::go
+  cmd_stacklit["cmd/stacklit\nStacklit"]:::go
+  internal_cli["internal/cli\nCommand-line interface"]:::go
   internal_renderer["internal/renderer\nOutput renderers"]:::go
+  internal_schema["internal/schema\nData schema definitions"]:::go
+  internal_summary["internal/summary\nAI-powered codebase summaries"]:::go
   internal_walker["internal/walker\nFile system walker"]:::go
-  internal_cli["internal/cli\nCommand-line interface"]:::go
-  internal_git["internal/git\nGit integration"]:::go
-  internal_graph["internal/graph\nDependency graph"]:::go
   npm["npm\nNpm"]:::go
+  npm_bin["npm/bin\nBin"]:::go
+  internal_graph["internal/graph\nDependency graph"]:::go
+  internal_monorepo["internal/monorepo\nMonorepo detection"]:::go
   assets["assets\nStatic assets"]:::go
   internal_config["internal/config\nConfiguration management"]:::go
+  internal_mcp["internal/mcp\nMCP server for AI agents"]:::go
+  internal_parser["internal/parser\nSource code parsers"]:::go
   internal_detect["internal/detect\nFramework and tool detection"]:::go
-  internal_schema["internal/schema\nData schema definitions"]:::go
-  npm_bin["npm/bin\nBin"]:::go
-  cmd_stacklit["cmd/stacklit\nStacklit"]:::go
+  internal_engine["internal/engine\nCore orchestration engine"]:::go
+  internal_git["internal/git\nGit integration"]:::go
   cmd_stacklit --> internal_cli
   internal_cli --> internal_engine
   internal_cli --> internal_git
@@ -44,3 +45,4 @@ graph LR
   internal_renderer --> assets
   internal_renderer --> internal_schema
   internal_summary --> internal_schema
+```