fix(cli): graceful error for cycles, export, embed when no graph.db exists

Use openReadonlyOrFail() instead of raw Database() constructor in the
export and cycles command handlers. Add fs.existsSync() guard in
buildEmbeddings(). Also export ./package.json in the exports map.

Closes #77
Closes #78

Impact: 1 functions changed, 1 affected

Author: github-actions[bot]

package.json

@@ -7,7 +7,8 @@
   "exports": {
     ".": {
       "import": "./src/index.js"
-    }
+    },
+    "./package.json": "./package.json"
   },
   "bin": {
     "codegraph": "./src/cli.js"

src/cli.js

@@ -2,12 +2,11 @@
 
 import fs from 'node:fs';
 import path from 'node:path';
-import Database from 'better-sqlite3';
 import { Command } from 'commander';
 import { buildGraph } from './builder.js';
 import { loadConfig } from './config.js';
 import { findCycles, formatCycles } from './cycles.js';
-import { findDbPath } from './db.js';
+import { openReadonlyOrFail } from './db.js';
 import { buildEmbeddings, EMBEDDING_STRATEGIES, MODELS, search } from './embedder.js';
 import { exportDOT, exportJSON, exportMermaid } from './export.js';
 import { setVerbose } from './logger.js';
@@ -275,7 +274,7 @@ program
   .option('--min-confidence <score>', 'Minimum edge confidence threshold (default: 0.5)', '0.5')
   .option('-o, --output <file>', 'Write to file instead of stdout')
   .action((opts) => {
-    const db = new Database(findDbPath(opts.db), { readonly: true });
+    const db = openReadonlyOrFail(opts.db);
     const exportOpts = {
       fileLevel: !opts.functions,
       noTests: resolveNoTests(opts),
@@ -314,7 +313,7 @@ program
   .option('--include-tests', 'Include test/spec files (overrides excludeTests config)')
   .option('-j, --json', 'Output as JSON')
   .action((opts) => {
-    const db = new Database(findDbPath(opts.db), { readonly: true });
+    const db = openReadonlyOrFail(opts.db);
     const cycles = findCycles(db, { fileLevel: !opts.functions, noTests: resolveNoTests(opts) });
     db.close();
 

src/embedder.js

@@ -324,6 +324,14 @@ export async function buildEmbeddings(rootDir, modelKey, customDbPath, options =
   const strategy = options.strategy || 'structured';
   const dbPath = customDbPath || findDbPath(null);
 
+  if (!fs.existsSync(dbPath)) {
+    console.error(
+      `No codegraph database found at ${dbPath}.\n` +
+        `Run "codegraph build" first to analyze your codebase.`,
+    );
+    process.exit(1);
+  }
+
   const db = new Database(dbPath);
   initEmbeddingsSchema(db);