fix: resolve ConfigCache.has() stat inflation and hook system errors (#497, #528)

#497: ConfigCache.has() delegated to get(), inflating hit/miss stats.
Reimplemented has() to check Map directly without touching metrics.
Applied to both core/config/ and infrastructure/scripts/ copies.

#528: precompact-session-digest.cjs failed in installed projects because
runner path didn't account for node_modules layout. Added path resolution
with fallback candidates. Also fixed:
- synapse-engine.cjs: replaced process.exit() with process.exitCode for
  clean stdout flush
- hook-runtime.js: create session file on first prompt when loadSession
  returns null (prevents silent updateSession failures)

Updated tests to match new behavior (process.exitCode, createSession export).

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

Author: oalanicolas

.aiox-core/core/config/config-cache.js

@@ -72,7 +72,16 @@ class ConfigCache {
    * @returns {boolean} True if key exists and is valid
    */
   has(key) {
-    return this.get(key) !== null;
+    if (!this.cache.has(key)) {
+      return false;
+    }
+    const timestamp = this.timestamps.get(key);
+    if (Date.now() - timestamp > this.ttl) {
+      this.cache.delete(key);
+      this.timestamps.delete(key);
+      return false;
+    }
+    return true;
   }
 
   /**

.aiox-core/core/synapse/runtime/hook-runtime.js

@@ -46,15 +46,24 @@ function resolveHookRuntime(input) {
   if (!fs.existsSync(synapsePath)) return null;
 
   try {
-    const { loadSession, cleanStaleSessions } = require(
+    const { loadSession, createSession, cleanStaleSessions } = require(
       path.join(cwd, '.aiox-core', 'core', 'synapse', 'session', 'session-manager.js'),
     );
     const { SynapseEngine } = require(
       path.join(cwd, '.aiox-core', 'core', 'synapse', 'engine.js'),
     );
 
     const sessionsDir = path.join(synapsePath, 'sessions');
-    const session = loadSession(sessionId, sessionsDir) || { prompt_count: 0 };
+
+    // Create session file on first prompt if it doesn't exist.
+    // Without this, updateSession() silently fails because loadSession() returns null.
+    let session = loadSession(sessionId, sessionsDir);
+    if (!session && sessionId) {
+      session = createSession(sessionId, cwd, sessionsDir);
+    }
+    if (!session) {
+      session = { prompt_count: 0 };
+    }
     const engine = new SynapseEngine(synapsePath);
 
     // AC3: Run cleanup on first prompt only (fire-and-forget)

.aiox-core/infrastructure/scripts/config-cache.js

@@ -71,7 +71,16 @@ class ConfigCache {
    * @returns {boolean} True if key exists and is valid
    */
   has(key) {
-    return this.get(key) !== null;
+    if (!this.cache.has(key)) {
+      return false;
+    }
+    const timestamp = this.timestamps.get(key);
+    if (Date.now() - timestamp > this.ttl) {
+      this.cache.delete(key);
+      this.timestamps.delete(key);
+      return false;
+    }
+    return true;
   }
 
   /**