fix(js-sdk): unpin useDefineForClassFields — make caller-directory resolution emit-invariant

.changeset/lucky-buttons-repair.md

@@ -0,0 +1,5 @@
+---
+'e2b': patch
+---
+
+Resolve the template builder's default file context path in the constructor instead of a class field initializer. Under `[[Define]]` class-field semantics (the default at `target: es2022+`), field initializers run in an extra `<instance_members_initializer>` stack frame, which threw off the fixed-depth caller-directory resolution — `.copy()` sources resolved against the SDK's own directory instead of the caller's. The constructor-body call is emit-invariant, so the `useDefineForClassFields: false` pin in tsconfig is no longer needed and has been removed.

packages/js-sdk/src/template/index.ts

@@ -66,16 +66,19 @@ export class TemplateBase
   // Force the next layer to be rebuilt
   private forceNextLayer: boolean = false
   private instructions: Instruction[] = []
-  private fileContextPath: PathLike =
-    runtime === 'browser' ? '.' : (getCallerDirectory(STACK_TRACE_DEPTH) ?? '.')
+  private fileContextPath: PathLike
   private fileIgnorePatterns: string[] = []
   private logsRefreshFrequency: number = 200
   private stackTraces: (string | undefined)[] = []
   private stackTracesEnabled: boolean = true
   private stackTracesOverride: string | undefined = undefined
 
   constructor(options?: TemplateOptions) {
-    this.fileContextPath = options?.fileContextPath ?? this.fileContextPath
+    this.fileContextPath =
+      options?.fileContextPath ??
+      (runtime === 'browser'
+        ? '.'
+        : (getCallerDirectory(STACK_TRACE_DEPTH) ?? '.'))
     this.fileIgnorePatterns =
       options?.fileIgnorePatterns ?? this.fileIgnorePatterns
   }

packages/js-sdk/tsconfig.json

@@ -3,12 +3,6 @@
     "outDir": "dist",
     "target": "es2022",
     "module": "esnext",
-    // Keep assignment (not `[[Define]]`) semantics for class fields. `target:
-    // es2022` would default this to `true`, which changes class-field emit and
-    // shifts stack frames — breaking the template builder's fixed-depth caller
-    // resolution (getCallerDirectory / per-step stack traces). Adopting define
-    // semantics should be a separate, deliberately tested change.
-    "useDefineForClassFields": false,
     "lib": [
       "dom",
       "es2022"