feat(cli): add version, indexPath, lastIndexed to status --json (#329)

Adds `version`, `indexPath`, and an ISO `lastIndexed` to `codegraph status --json`, plus a `CodeGraph.getLastIndexedAt()` library method. `agentCount` dropped (no clear consumer). Reworked from contributor PRs #333 and #480.

Co-Authored-By: Javier Gómez <199902626+12122J@users.noreply.github.com>
Co-Authored-By: Ran <8403607+eddieran@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/bin/codegraph.ts

@@ -676,7 +676,13 @@ program
     try {
       if (!isInitialized(projectPath)) {
         if (options.json) {
-          console.log(JSON.stringify({ initialized: false, projectPath }));
+          console.log(JSON.stringify({
+            initialized: false,
+            version: packageJson.version,
+            projectPath,
+            indexPath: getCodeGraphDir(projectPath),
+            lastIndexed: null,
+          }));
           return;
         }
         console.log(chalk.bold('\nCodeGraph Status\n'));
@@ -695,9 +701,13 @@ program
 
       // JSON output mode
       if (options.json) {
+        const lastIndexedMs = cg.getLastIndexedAt();
         console.log(JSON.stringify({
           initialized: true,
+          version: packageJson.version,
           projectPath,
+          indexPath: getCodeGraphDir(projectPath),
+          lastIndexed: lastIndexedMs != null ? new Date(lastIndexedMs).toISOString() : null,
           fileCount: stats.fileCount,
           nodeCount: stats.nodeCount,
           edgeCount: stats.edgeCount,

src/db/queries.ts

@@ -1421,6 +1421,17 @@ export class QueryBuilder {
     return rows.map(rowToFileRecord);
   }
 
+  /**
+   * Most recent index timestamp (ms since epoch) across all tracked files, or
+   * null when nothing is indexed yet. One indexed aggregate, no per-row scan. (#329)
+   */
+  getLastIndexedAt(): number | null {
+    const row = this.db
+      .prepare('SELECT MAX(indexed_at) AS last FROM files')
+      .get() as { last: number | null } | undefined;
+    return row?.last ?? null;
+  }
+
   /**
    * Get files that need re-indexing (hash changed)
    */

src/index.ts

@@ -576,6 +576,15 @@ export class CodeGraph {
     return this.orchestrator.getChangedFiles();
   }
 
+  /**
+   * Most recent index timestamp (ms since epoch) across all tracked files, or
+   * null when nothing is indexed yet. Lets library consumers check index
+   * freshness without shelling out to `codegraph status --json`. (#329)
+   */
+  getLastIndexedAt(): number | null {
+    return this.queries.getLastIndexedAt();
+  }
+
   /**
    * Extract nodes and edges from source code (without storing)
    */