10 architectural patterns behind Claude Code

The 10 patterns below distill every non-obvious design decision into a transferable form — concrete proof of a simple thesis: the workflow around a capable model decides how much of its capability ships. Each one solves a problem every production agent eventually hits: context exhaustion, token waste, unsafe concurrent tool use, or session state that drifts between restarts.

AsyncGenerator as agent loop

The outer loop yields Messages and uses a typed Terminal return, giving natural backpressure and cooperative cancellation without callbacks.

Speculative tool execution

Read-only tools start running during model streaming, before the response token stream completes — cutting perceived latency on the common read path.

Concurrent-safe batching

Tools are partitioned by safety class; reads run in parallel, writes are serialized — concurrency without race conditions.

Fork agents for cache sharing

Parallel child agents share a byte-identical prompt prefix, so the cache is hit on every child's first token — ~95% input-token savings on fan-out tasks.

4-layer context compression

Snip, microcompact, collapse, autocompact — each lighter than the next; the lightest layer that fits the context wins.

File-based memory with LLM recall

Memories live as plain files; a Sonnet side-query selects which ones are relevant at session start — semantic recall without a vector database.

Two-phase skill loading

Frontmatter is parsed at startup for routing; full skill content is loaded only on invocation — keeps startup fast regardless of skill count.

Sticky latches for cache stability

Once a beta header is sent, it is never unset mid-session — prevents prompt-cache invalidation from header churn.

Slot reservation

Output is capped at 8K tokens by default; the cap escalates to 64K on a hit — saves context in 99% of requests while allowing long outputs when needed.

Hook config snapshot

Hook configuration is frozen at startup, not re-read per tool call — prevents runtime injection attacks via config mutation.