fix(TsPathRewriter): rewrite cross-module import paths after compilation

When compiling multiple ts_* source directories to dist_ts_* outputs,
imports like '../ts_shared/helper.js' now correctly become
'../dist_ts_shared/helper.js' in the compiled output.

Uses targeted regex patterns that only match import/export/require
statements, avoiding false positives in strings or comments.

ts/mod_pathrewrite/classes.tspathrewriter.ts

@@ -0,0 +1,200 @@
+import * as fs from 'fs';
+import * as path from 'path';
+import { FsHelpers } from '../mod_fs/index.js';
+
+/**
+ * Interface for folder mapping between source and destination
+ */
+export interface IFolderMapping {
+  sourceFolder: string;  // e.g., 'ts_shared'
+  destFolder: string;    // e.g., 'dist_ts_shared'
+}
+
+/**
+ * TsPathRewriter handles rewriting import paths in compiled JavaScript files.
+ *
+ * When TypeScript compiles files that import from sibling directories like:
+ *   import { helper } from '../ts_shared/helper.js';
+ *
+ * This class rewrites them to point to the compiled output directories:
+ *   import { helper } from '../dist_ts_shared/helper.js';
+ *
+ * This is necessary because the unpack feature flattens nested output structures,
+ * changing the relative paths between modules.
+ */
+export class TsPathRewriter {
+  private mappings: IFolderMapping[];
+
+  constructor(mappings: IFolderMapping[]) {
+    this.mappings = mappings;
+  }
+
+  /**
+   * Create a TsPathRewriter from glob patterns used in compilation
+   *
+   * @param globPatterns - Map of source patterns to destination directories
+   *   e.g., { './ts_core/**\/*.ts': './dist_ts_core', './ts_shared/**\/*.ts': './dist_ts_shared' }
+   * @returns TsPathRewriter instance with extracted folder mappings
+   */
+  public static fromGlobPatterns(globPatterns: Record<string, string>): TsPathRewriter {
+    const mappings: IFolderMapping[] = [];
+
+    for (const [sourcePattern, destDir] of Object.entries(globPatterns)) {
+      const sourceFolder = FsHelpers.extractSourceFolder(sourcePattern);
+      const destFolder = FsHelpers.extractSourceFolder(destDir);
+
+      if (sourceFolder && destFolder) {
+        mappings.push({ sourceFolder, destFolder });
+      }
+    }
+
+    return new TsPathRewriter(mappings);
+  }
+
+  /**
+   * Get the current folder mappings
+   */
+  public getMappings(): IFolderMapping[] {
+    return [...this.mappings];
+  }
+
+  /**
+   * Rewrite import paths in a single file
+   *
+   * @param filePath - Absolute path to the file to rewrite
+   * @returns true if file was modified, false otherwise
+   */
+  public async rewriteFile(filePath: string): Promise<boolean> {
+    // Only process .js and .d.ts files
+    if (!filePath.endsWith('.js') && !filePath.endsWith('.d.ts')) {
+      return false;
+    }
+
+    try {
+      const content = await fs.promises.readFile(filePath, 'utf8');
+      const rewritten = this.rewriteContent(content);
+
+      if (rewritten !== content) {
+        await fs.promises.writeFile(filePath, rewritten, 'utf8');
+        return true;
+      }
+
+      return false;
+    } catch (error) {
+      // File doesn't exist or other error
+      return false;
+    }
+  }
+
+  /**
+   * Rewrite import paths in all .js and .d.ts files in a directory (recursively)
+   *
+   * @param dirPath - Absolute path to the directory
+   * @returns Number of files modified
+   */
+  public async rewriteDirectory(dirPath: string): Promise<number> {
+    let modifiedCount = 0;
+
+    const processDir = async (currentDir: string): Promise<void> => {
+      const entries = await FsHelpers.listDirectory(currentDir);
+
+      for (const entry of entries) {
+        const fullPath = path.join(currentDir, entry.name);
+
+        if (entry.isDirectory) {
+          await processDir(fullPath);
+        } else if (entry.isFile && (entry.name.endsWith('.js') || entry.name.endsWith('.d.ts'))) {
+          const wasModified = await this.rewriteFile(fullPath);
+          if (wasModified) {
+            modifiedCount++;
+          }
+        }
+      }
+    };
+
+    if (await FsHelpers.directoryExists(dirPath)) {
+      await processDir(dirPath);
+    }
+
+    return modifiedCount;
+  }
+
+  /**
+   * Rewrite import paths in content string
+   *
+   * This method only modifies actual import/export/require statements,
+   * not arbitrary strings or comments that might contain similar patterns.
+   *
+   * @param content - File content to process
+   * @returns Rewritten content
+   */
+  public rewriteContent(content: string): string {
+    if (this.mappings.length === 0) {
+      return content;
+    }
+
+    let result = content;
+
+    for (const { sourceFolder, destFolder } of this.mappings) {
+      // Skip if source and dest are the same
+      if (sourceFolder === destFolder) {
+        continue;
+      }
+
+      // Pattern 1: ES Module imports/exports with 'from'
+      // Matches: from '../ts_shared/...' or from '../../ts_shared/...'
+      // Also handles: export { x } from '../ts_shared/...'
+      const fromPattern = new RegExp(
+        `(from\\s*['"])((?:\\.\\.\\/)+)${this.escapeRegex(sourceFolder)}(\\/[^'"]*['"])`,
+        'g'
+      );
+      result = result.replace(fromPattern, `$1$2${destFolder}$3`);
+
+      // Pattern 2: Dynamic imports
+      // Matches: import('../ts_shared/...')
+      const dynamicImportPattern = new RegExp(
+        `(import\\s*\\(\\s*['"])((?:\\.\\.\\/)+)${this.escapeRegex(sourceFolder)}(\\/[^'"]*['"]\\s*\\))`,
+        'g'
+      );
+      result = result.replace(dynamicImportPattern, `$1$2${destFolder}$3`);
+
+      // Pattern 3: CommonJS require
+      // Matches: require('../ts_shared/...')
+      const requirePattern = new RegExp(
+        `(require\\s*\\(\\s*['"])((?:\\.\\.\\/)+)${this.escapeRegex(sourceFolder)}(\\/[^'"]*['"]\\s*\\))`,
+        'g'
+      );
+      result = result.replace(requirePattern, `$1$2${destFolder}$3`);
+    }
+
+    return result;
+  }
+
+  /**
+   * Escape special regex characters in a string
+   */
+  private escapeRegex(str: string): string {
+    return str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
+  }
+}
+
+/**
+ * Convenience function to rewrite import paths in output directories
+ *
+ * @param globPatterns - Map of source patterns to destination directories
+ * @param outputDirs - List of output directories to process
+ * @returns Total number of files modified
+ */
+export async function rewriteImportPaths(
+  globPatterns: Record<string, string>,
+  outputDirs: string[]
+): Promise<number> {
+  const rewriter = TsPathRewriter.fromGlobPatterns(globPatterns);
+  let totalModified = 0;
+
+  for (const dir of outputDirs) {
+    totalModified += await rewriter.rewriteDirectory(dir);
+  }
+
+  return totalModified;
+}