diff --git a/e2e/lib/event-parser.ts b/e2e/lib/event-parser.ts
index 177a46b7..9db6066a 100644
--- a/e2e/lib/event-parser.ts
+++ b/e2e/lib/event-parser.ts
@@ -56,14 +56,20 @@ function tryParseEvent(text: string, events: ParsedEvent[]): void {
       events.push({ ...data, raw: text })
     }
   } catch {
-    // Retry with non-ASCII characters escaped as Unicode sequences to work
-    // around JSC JSON.parse issues with multi-byte characters in large strings
+    // Fallback: write to temp file and read back to force fresh string allocation,
+    // working around potential JSC string representation issues with JSON.parse
     try {
-      const escaped = text.replace(
-        /[\u0080-\uffff]/g,
-        (c) => `\\u${c.charCodeAt(0).toString(16).padStart(4, "0")}`,
+      const { writeFileSync, readFileSync, unlinkSync } = require("node:fs")
+      const { tmpdir } = require("node:os")
+      const { join } = require("node:path")
+      const tmpFile = join(
+        tmpdir(),
+        `event-parse-${Date.now()}-${Math.random().toString(36).slice(2)}.json`,
       )
-      const data = JSON.parse(escaped) as RunEvent
+      writeFileSync(tmpFile, text)
+      const fresh = readFileSync(tmpFile, "utf-8")
+      unlinkSync(tmpFile)
+      const data = JSON.parse(fresh) as RunEvent
       if (data.type) {
         events.push({ ...data, raw: text })
       }
diff --git a/e2e/perstack-cli/providers.test.ts b/e2e/perstack-cli/providers.test.ts
index d202e1fd..4610886b 100644
--- a/e2e/perstack-cli/providers.test.ts
+++ b/e2e/perstack-cli/providers.test.ts
@@ -69,26 +69,36 @@ describe.concurrent("LLM Providers", () => {
             process.stderr.write(`[DEBUG ${provider}] parse OK\n`)
           } catch (e) {
             process.stderr.write(`[DEBUG ${provider}] parse FAIL: ${(e as Error).message}\n`)
-            const escaped = line.replace(
-              /[\u0080-\uffff]/g,
-              (c) => `\\u${c.charCodeAt(0).toString(16).padStart(4, "0")}`,
+            // Try file round-trip
+            const { writeFileSync, readFileSync, unlinkSync } = await import("node:fs")
+            const tmpFile = `/tmp/debug-parse-${Date.now()}.json`
+            writeFileSync(tmpFile, line)
+            const fresh = readFileSync(tmpFile, "utf-8")
+            unlinkSync(tmpFile)
+            process.stderr.write(
+              `[DEBUG ${provider}] freshLen=${fresh.length} match=${fresh === line}\n`,
             )
             try {
-              JSON.parse(escaped)
-              process.stderr.write(`[DEBUG ${provider}] escaped parse OK!\n`)
+              JSON.parse(fresh)
+              process.stderr.write(`[DEBUG ${provider}] file roundtrip parse OK!\n`)
             } catch (e2) {
               process.stderr.write(
-                `[DEBUG ${provider}] escaped parse FAIL: ${(e2 as Error).message}\n`,
+                `[DEBUG ${provider}] file roundtrip parse FAIL: ${(e2 as Error).message}\n`,
               )
             }
-            const buf = Buffer.from(line)
-            process.stderr.write(
-              `[DEBUG ${provider}] byteLen=${buf.length} charLen=${line.length}\n`,
-            )
-            const first20hex = Array.from(buf.subarray(0, 20))
-              .map((b) => b.toString(16).padStart(2, "0"))
-              .join(" ")
-            process.stderr.write(`[DEBUG ${provider}] first20hex=${first20hex}\n`)
+            // Try TextEncoder/TextDecoder round-trip
+            const encoded = new TextEncoder().encode(line)
+            const decoded = new TextDecoder().decode(encoded)
+            try {
+              JSON.parse(decoded)
+              process.stderr.write(`[DEBUG ${provider}] TextEncoder roundtrip parse OK!\n`)
+            } catch (e3) {
+              process.stderr.write(
+                `[DEBUG ${provider}] TextEncoder roundtrip parse FAIL: ${(e3 as Error).message}\n`,
+              )
+            }
+            // Try reading stdout file directly as Buffer
+            process.stderr.write(`[DEBUG ${provider}] rawStdoutLen=${result.stdout.length}\n`)
           }
         } else {
           process.stderr.write(`[DEBUG ${provider}] startRun NOT FOUND in any line\n`)