fix: shell block references and complex env value serialization

Two follow-ups to the function-block context-variable refactor:

- resolveCodeWithContextVars now emits `$__blockRef_N` for shell
  function blocks so the script dereferences the env var injected
  by the executor. Other languages still receive the bare identifier.
- The function-execute route now JSON-stringifies non-primitive
  values when building shell env vars, replacing the previous
  `String(v)` call that produced `[object Object]` for objects/arrays.

Co-Authored-By: Octopus <liyuan851277048@icloud.com>

Author: octo-patch

apps/sim/app/api/function/execute/route.ts

@@ -586,6 +586,26 @@ function cleanStdout(stdout: string): string {
   return stdout
 }
 
+/**
+ * Serializes a value for use as a shell environment variable. Strings pass through
+ * unchanged; primitives are coerced via `String`; objects, arrays, and other complex
+ * values are JSON-stringified so that referencing them via `$VAR` yields a useful
+ * representation instead of `[object Object]`. `null`/`undefined` become an empty
+ * string to match POSIX env semantics.
+ */
+function serializeForShellEnv(value: unknown): string {
+  if (value === null || value === undefined) return ''
+  if (typeof value === 'string') return value
+  if (typeof value === 'number' || typeof value === 'boolean' || typeof value === 'bigint') {
+    return String(value)
+  }
+  try {
+    return JSON.stringify(value) ?? ''
+  } catch {
+    return String(value)
+  }
+}
+
 async function maybeExportSandboxFileToWorkspace(args: {
   authUserId: string
   workflowId?: string
@@ -788,10 +808,10 @@ export async function POST(req: NextRequest) {
 
       const shellEnvs: Record<string, string> = {}
       for (const [k, v] of Object.entries(envVars)) {
-        shellEnvs[k] = String(v)
+        shellEnvs[k] = serializeForShellEnv(v)
       }
       for (const [k, v] of Object.entries(contextVariables)) {
-        shellEnvs[k] = String(v)
+        shellEnvs[k] = serializeForShellEnv(v)
       }
 
       logger.info(`[${requestId}] E2B shell execution`, {

apps/sim/executor/variables/resolver.ts

@@ -237,6 +237,7 @@ export class VariableResolver {
 
     let replacementError: Error | null = null
 
+    const isShell = language === 'shell'
     const blockRefByMatch = new Map<string, string>()
 
     let result = replaceValidReferences(template, (match) => {
@@ -254,11 +255,15 @@ export class VariableResolver {
 
           const effectiveValue = resolved === RESOLVED_EMPTY ? null : resolved
 
-          // Block output: store in contextVarAccumulator, replace with variable name
+          // Block output: store in contextVarAccumulator, replace with variable name.
+          // For shell, emit `$__blockRef_N` so the script dereferences the env var
+          // injected by the function-execute route; other languages receive the bare
+          // identifier and read it as a global injected into the VM.
           const varName = `__blockRef_${Object.keys(contextVarAccumulator).length}`
           contextVarAccumulator[varName] = effectiveValue
-          blockRefByMatch.set(match, varName)
-          return varName
+          const replacement = isShell ? `$${varName}` : varName
+          blockRefByMatch.set(match, replacement)
+          return replacement
         }
 
         const resolved = this.resolveReference(match, resolutionContext)