diff --git a/changelog.md b/changelog.md
index a18d1f3..ee1758b 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 2026-03-05 - 4.1.18 - fix(mod_compiler)
+add diagnostic logging of output directory states after compilation and after import-path rewriting to aid debugging
+
+- Imported fs to allow reading output directories for diagnostics
+- Logs entries and directory counts for each successful output directory both pre- and post-import-path-rewrite
+- Diagnostics are gated by !isQuiet && !isJson and are read-only (no behavior change)
+- Tags used: 'diag' (post-compilation) and 'diag-post-rewrite' (after rewriting) to help identify missing or unexpected output folders
+
 ## 2026-03-05 - 4.1.17 - fix(tsunpacker)
 use synchronous fs operations in tsunpacker to avoid readdir race conditions
 
diff --git a/ts/00_commitinfo_data.ts b/ts/00_commitinfo_data.ts
index dfbe6ff..16cf670 100644
--- a/ts/00_commitinfo_data.ts
+++ b/ts/00_commitinfo_data.ts
@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@git.zone/tsbuild',
-  version: '4.1.17',
+  version: '4.1.18',
   description: 'A tool for compiling TypeScript files using the latest nightly features, offering flexible APIs and a CLI for streamlined development.'
 }
diff --git a/ts/mod_compiler/classes.tscompiler.ts b/ts/mod_compiler/classes.tscompiler.ts
index 9ef52de..7d2c613 100644
--- a/ts/mod_compiler/classes.tscompiler.ts
+++ b/ts/mod_compiler/classes.tscompiler.ts
@@ -1,5 +1,6 @@
 import type { CompilerOptions, Diagnostic, Program } from 'typescript';
 import typescript from 'typescript';
+import * as fs from 'fs';
 import * as smartdelay from '@push.rocks/smartdelay';
 import * as smartpromise from '@push.rocks/smartpromise';
 import * as smartpath from '@push.rocks/smartpath';
@@ -371,6 +372,21 @@ export class TsCompiler {
         successfulOutputDirs.push(destDir);
       }
 
+      // Diagnostic: log all output directory states after each compilation
+      if (!isQuiet && !isJson) {
+        for (const prevDir of successfulOutputDirs) {
+          try {
+            const entries = fs.readdirSync(prevDir);
+            const dirs = entries.filter(e => {
+              try { return fs.statSync(prevDir + '/' + e).isDirectory(); } catch { return false; }
+            });
+            console.log(`   📋 [diag] ${prevDir.replace(this.cwd + '/', '')}: ${entries.length} entries, ${dirs.length} dirs`);
+          } catch {
+            console.log(`   📋 [diag] ${prevDir.replace(this.cwd + '/', '')}: MISSING!`);
+          }
+        }
+      }
+
     }
 
     // Rewrite import paths in all output directories to handle cross-module references
@@ -385,6 +401,21 @@ export class TsCompiler {
       if (totalRewritten > 0 && !isQuiet && !isJson) {
         console.log(`   🔄 Rewrote import paths in ${totalRewritten} file${totalRewritten !== 1 ? 's' : ''}`);
       }
+
+      // Diagnostic: log output directory states after path rewriting
+      if (!isQuiet && !isJson) {
+        for (const dir of successfulOutputDirs) {
+          try {
+            const entries = fs.readdirSync(dir);
+            const dirs = entries.filter(e => {
+              try { return fs.statSync(dir + '/' + e).isDirectory(); } catch { return false; }
+            });
+            console.log(`   📋 [diag-post-rewrite] ${dir.replace(this.cwd + '/', '')}: ${entries.length} entries, ${dirs.length} dirs`);
+          } catch {
+            console.log(`   📋 [diag-post-rewrite] ${dir.replace(this.cwd + '/', '')}: MISSING!`);
+          }
+        }
+      }
     }
 
     // Merge all error summaries