fix(agent): merge abort signals instead of overriding caller's signal

When both timeoutMs and a caller-provided abortSignal were set, the
timeout signal silently replaced the caller's signal. Now they are
combined via mergeAbortSignals() so either source can cancel the run.

Also removes dead array-handling branch in text-tool-extractor.ts
(extractJSONObjects only returns objects, never arrays).

src/agent/agent.ts

@@ -50,6 +50,19 @@ import {
 
 const ZERO_USAGE: TokenUsage = { input_tokens: 0, output_tokens: 0 }
 
+/**
+ * Combine two {@link AbortSignal}s so that aborting either one cancels the
+ * returned signal.  Works on Node 18+ (no `AbortSignal.any` required).
+ */
+function mergeAbortSignals(a: AbortSignal, b: AbortSignal): AbortSignal {
+  const controller = new AbortController()
+  if (a.aborted || b.aborted) { controller.abort(); return controller.signal }
+  const abort = () => controller.abort()
+  a.addEventListener('abort', abort, { once: true })
+  b.addEventListener('abort', abort, { once: true })
+  return controller.signal
+}
+
 function addUsage(a: TokenUsage, b: TokenUsage): TokenUsage {
   return {
     input_tokens: a.input_tokens + b.input_tokens,
@@ -298,11 +311,17 @@ export class Agent {
       const timeoutSignal = this.config.timeoutMs !== undefined && this.config.timeoutMs > 0
         ? AbortSignal.timeout(this.config.timeoutMs)
         : undefined
+      // Merge caller-provided abortSignal with the timeout signal so that
+      // either cancellation source is respected.
+      const callerAbort = callerOptions?.abortSignal
+      const effectiveAbort = timeoutSignal && callerAbort
+        ? mergeAbortSignals(timeoutSignal, callerAbort)
+        : timeoutSignal ?? callerAbort
       const runOptions: RunOptions = {
         ...callerOptions,
         onMessage: internalOnMessage,
         ...(needsRunId ? { runId: generateRunId() } : undefined),
-        ...(timeoutSignal ? { abortSignal: timeoutSignal } : undefined),
+        ...(effectiveAbort ? { abortSignal: effectiveAbort } : undefined),
       }
 
       const result = await runner.run(messages, runOptions)

src/tool/text-tool-extractor.ts

@@ -211,15 +211,6 @@ export function extractToolCallsFromText(
 
   const results: ToolUseBlock[] = []
   for (const obj of jsonObjects) {
-    // Handle array of tool calls
-    if (Array.isArray(obj)) {
-      for (const item of obj) {
-        const block = parseToolCallJSON(item, nameSet)
-        if (block !== null) results.push(block)
-      }
-      continue
-    }
-
     const block = parseToolCallJSON(obj, nameSet)
     if (block !== null) results.push(block)
   }