fix: renameAlias data corruption, empty sessionId match, NaN threshold

- Fix renameAlias() leaving orphaned newAlias key on save failure,
  causing in-memory data corruption with both old and new keys present
- Add sessionPath validation to setAlias() to reject empty/null paths
- Guard getSessionById() against empty string matching all sessions
  (startsWith('') is always true in JavaScript)
- Fix suggest-compact.js NaN comparison when COMPACT_THRESHOLD env var
  is set to a non-numeric value — falls back to 50 instead of silently
  disabling the threshold check
- Sync suggest-compact.js to .cursor/ copy

.cursor/skills/strategic-compact/suggest-compact.js

@@ -0,0 +1,74 @@
+#!/usr/bin/env node
+/**
+ * Strategic Compact Suggester
+ *
+ * Cross-platform (Windows, macOS, Linux)
+ *
+ * Runs on PreToolUse or periodically to suggest manual compaction at logical intervals
+ *
+ * Why manual over auto-compact:
+ * - Auto-compact happens at arbitrary points, often mid-task
+ * - Strategic compacting preserves context through logical phases
+ * - Compact after exploration, before execution
+ * - Compact after completing a milestone, before starting next
+ */
+
+const fs = require('fs');
+const path = require('path');
+const {
+  getTempDir,
+  writeFile,
+  log
+} = require('../lib/utils');
+
+async function main() {
+  // Track tool call count (increment in a temp file)
+  // Use a session-specific counter file based on session ID from environment
+  // or parent PID as fallback
+  const sessionId = process.env.CLAUDE_SESSION_ID || String(process.ppid) || 'default';
+  const counterFile = path.join(getTempDir(), `claude-tool-count-${sessionId}`);
+  const rawThreshold = parseInt(process.env.COMPACT_THRESHOLD || '50', 10);
+  const threshold = Number.isFinite(rawThreshold) ? rawThreshold : 50;
+
+  let count = 1;
+
+  // Read existing count or start at 1
+  // Use fd-based read+write to reduce (but not eliminate) race window
+  // between concurrent hook invocations
+  try {
+    const fd = fs.openSync(counterFile, 'a+');
+    try {
+      const buf = Buffer.alloc(64);
+      const bytesRead = fs.readSync(fd, buf, 0, 64, 0);
+      if (bytesRead > 0) {
+        const parsed = parseInt(buf.toString('utf8', 0, bytesRead).trim(), 10);
+        count = Number.isFinite(parsed) ? parsed + 1 : 1;
+      }
+      // Truncate and write new value
+      fs.ftruncateSync(fd, 0);
+      fs.writeSync(fd, String(count), 0);
+    } finally {
+      fs.closeSync(fd);
+    }
+  } catch {
+    // Fallback: just use writeFile if fd operations fail
+    writeFile(counterFile, String(count));
+  }
+
+  // Suggest compact after threshold tool calls
+  if (count === threshold) {
+    log(`[StrategicCompact] ${threshold} tool calls reached - consider /compact if transitioning phases`);
+  }
+
+  // Suggest at regular intervals after threshold
+  if (count > threshold && count % 25 === 0) {
+    log(`[StrategicCompact] ${count} tool calls - good checkpoint for /compact if context is stale`);
+  }
+
+  process.exit(0);
+}
+
+main().catch(err => {
+  console.error('[StrategicCompact] Error:', err.message);
+  process.exit(0);
+});

scripts/hooks/suggest-compact.js

@@ -27,7 +27,8 @@ async function main() {
   // or parent PID as fallback
   const sessionId = process.env.CLAUDE_SESSION_ID || String(process.ppid) || 'default';
   const counterFile = path.join(getTempDir(), `claude-tool-count-${sessionId}`);
-  const threshold = parseInt(process.env.COMPACT_THRESHOLD || '50', 10);
+  const rawThreshold = parseInt(process.env.COMPACT_THRESHOLD || '50', 10);
+  const threshold = Number.isFinite(rawThreshold) ? rawThreshold : 50;
 
   let count = 1;
 

scripts/lib/session-aliases.js

@@ -189,6 +189,11 @@ function setAlias(alias, sessionPath, title = null) {
     return { success: false, error: 'Alias name cannot be empty' };
   }
 
+  // Validate session path
+  if (!sessionPath || typeof sessionPath !== 'string' || sessionPath.trim().length === 0) {
+    return { success: false, error: 'Session path cannot be empty' };
+  }
+
   if (!/^[a-zA-Z0-9_-]+$/.test(alias)) {
     return { success: false, error: 'Alias name must contain only letters, numbers, dashes, and underscores' };
   }
@@ -325,8 +330,9 @@ function renameAlias(oldAlias, newAlias) {
     };
   }
 
-  // Restore old alias on failure
+  // Restore old alias and remove new alias on failure
   data.aliases[oldAlias] = aliasData;
+  delete data.aliases[newAlias];
   return { success: false, error: 'Failed to rename alias' };
 }
 

scripts/lib/session-manager.js

@@ -271,7 +271,7 @@ function getSessionById(sessionId, includeContent = false) {
     if (!metadata) continue;
 
     // Check if session ID matches (short ID or full filename without .tmp)
-    const shortIdMatch = metadata.shortId !== 'no-id' && metadata.shortId.startsWith(sessionId);
+    const shortIdMatch = sessionId.length > 0 && metadata.shortId !== 'no-id' && metadata.shortId.startsWith(sessionId);
     const filenameMatch = filename === sessionId || filename === `${sessionId}.tmp`;
     const noIdMatch = metadata.shortId === 'no-id' && filename === `${sessionId}-session.tmp`;