diff --git a/packages/code-runtime/code-runtime-worker/src/index.ts b/packages/code-runtime/code-runtime-worker/src/index.ts
index f59f3e8d9a..0fa66dbd71 100644
--- a/packages/code-runtime/code-runtime-worker/src/index.ts
+++ b/packages/code-runtime/code-runtime-worker/src/index.ts
@@ -269,7 +269,7 @@ export class WorkerCodeRuntime extends CodeRuntime {
     if (this.disposed) throw new Error('dsh-code-runtime-worker: run() after disposal')
     const bindings = this.validateBindings(request)
     if (request.signal?.aborted) {
-      return { logs: [], error: { kind: 'abort', message: String(request.signal.reason) } }
+      return this.failureBeforeWorker({ kind: 'abort', message: String(request.signal.reason) })
     }
 
     let code: string
@@ -280,12 +280,17 @@ export class WorkerCodeRuntime extends CodeRuntime {
       // A program that does not survive the type-strip (syntax error,
       // non-erasable syntax like `enum`) is a program failure, reported the
       // same way a thrown exception would be — and no worker ever spawns.
-      return { logs: [], error: { kind: 'exception', message: messageOf(error) } }
+      return this.failureBeforeWorker({ kind: 'exception', message: messageOf(error) })
     }
 
     return await this.execute(request, code, bindings)
   }
 
+  /** Apply the outer-output ledger to failures that occur before a worker owns one. */
+  private failureBeforeWorker(error: CodeRunFailure): CodeRunResult {
+    return new OutputLedger(this.config.maxOutputBytes).failure([], error)
+  }
+
   /** Reject (seam misuse) malformed binding namespaces: non-identifier or reserved globals, duplicates, and the `console` collision. */
   private validateBindings(request: CodeRunRequest): Map<string, Record<string, CodeBindingFunction>> {
     const bindings = new Map<string, Record<string, CodeBindingFunction>>()
@@ -405,9 +410,19 @@ export class WorkerCodeRuntime extends CodeRuntime {
           reply({ type: 'reply', id: message.id, ok: false, message: `unknown binding ${JSON.stringify(`${message.global}.${message.name}`)}` })
           return
         }
+        let args: CodeJsonValue | undefined
+        try {
+          args = snapshotJsonValue(message.args) as CodeJsonValue | undefined
+        } catch {
+          args = undefined
+        }
+        if (args === undefined) {
+          reply({ type: 'reply', id: message.id, ok: false, message: 'binding arguments must be lossless JSON' })
+          return
+        }
         void (async () => {
           try {
-            const resolved = await fn(message.args)
+            const resolved = await fn(args)
             let value: CodeJsonValue | undefined
             try {
               value = snapshotJsonValue(resolved)
diff --git a/packages/code-runtime/code-runtime-worker/tests/runtime.spec.ts b/packages/code-runtime/code-runtime-worker/tests/runtime.spec.ts
index 5615062286..8bcee8389b 100644
--- a/packages/code-runtime/code-runtime-worker/tests/runtime.spec.ts
+++ b/packages/code-runtime/code-runtime-worker/tests/runtime.spec.ts
@@ -171,6 +171,19 @@ describe('WorkerCodeRuntime — budgets and containment (real workers)', () => {
     expect(result.error).toEqual({ kind: 'abort', message: 'too-late' })
   })
 
+  it('applies the outer-output cap to failures before worker startup', async () => {
+    const capped = await setup({ maxOutputBytes: 64 })
+    const controller = new AbortController()
+    controller.abort('A'.repeat(1_000))
+    const aborted = await capped.runtime.run({ program: 'return 1', bindings: [], signal: controller.signal })
+    expect(aborted).toEqual({ logs: [], error: { kind: 'output-limit', message: 'outer output exceeded 64 bytes' } })
+
+    const minimal = await setup({ maxOutputBytes: 4 })
+    const invalid = await minimal.runtime.run({ program: 'enum E { A }\nreturn 1', bindings: [] })
+    expect(invalid.error?.kind).toBe('output-limit')
+    expect(Buffer.byteLength(JSON.stringify(invalid.logs), 'utf8') + Buffer.byteLength(JSON.stringify(invalid.error?.message), 'utf8')).toBeLessThanOrEqual(4)
+  })
+
   it('drops a binding resolution that lands after the run settled', async () => {
     const { runtime } = await setup()
     const controller = new AbortController()
@@ -449,6 +462,41 @@ describe('WorkerCodeRuntime — hostile programs (real workers)', () => {
     }))
   })
 
+  it('rejects forged lossy binding arguments again at the host boundary', async () => {
+    const { runtime } = await setup()
+    let calls = 0
+    const result = await runtime.run({
+      program: `
+        const { parentPort } = await import('node:worker_threads');
+        const forged = (id, args) => new Promise((resolve) => {
+          const receive = (message) => {
+            if (message?.type !== 'reply' || message.id !== id) return;
+            parentPort.off('message', receive);
+            resolve(message);
+          };
+          parentPort.on('message', receive);
+          parentPort.postMessage({ type: 'call', id, global: 'tools', name: 'never', args });
+        });
+        const sparse = []; sparse.length = 1;
+        const cycle = {}; cycle.self = cycle;
+        return await Promise.all([
+          forged(8001, new Date()),
+          forged(8002, -0),
+          forged(8003, sparse),
+          forged(8004, cycle),
+        ]);
+      `,
+      bindings: tools({ never: async () => { calls += 1; return null } }),
+    })
+    expect(calls).toBe(0)
+    expect(result.value).toEqual([8001, 8002, 8003, 8004].map(id => ({
+      type: 'reply',
+      id,
+      ok: false,
+      message: 'binding arguments must be lossless JSON',
+    })))
+  })
+
   it('contains throwing getters while snapshotting binding resolutions', async () => {
     const { runtime } = await setup()
     const result = await runtime.run({