Option D directly addresses cache entries expiring before later batch requests are processed. Anthropic’s batch-processing documentation specifically notes that Message Batches can take longer than five minutes and recommends the one-hour prompt-cache duration for batches containing shared context. The prompt-caching documentation confirms that the default TTL is five minutes and that " ttl " : " 1h " creates an extended entry.

Option A may improve cache locality, but it introduces the sequential-processing latency explicitly prohibited by the requirement. Option B seeds the cache initially, but the prewarmed entry still expires after five minutes unless the TTL is extended; it therefore does not solve misses among requests scheduled later. Option C places the breakpoint on request-specific content, defeating reuse of the stable 8,000-token prefix and attempting to cache scripts that are not byte-for-byte identical.

The system should retain the breakpoint at the end of the shared system content and apply the one-hour TTL there. Cache-usage fields should then be monitored to confirm that cache_read_input_tokens rises and later batch requests reuse the intended prefix.

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