Claude Code adds a 1-hour prompt cache to cut your token bill
v2.1.243 also curates your /model picker, adds keyless sign-in, flags runaway /loop tasks, and shrinks the Linux binary from 340 MB to 75 MB.
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The 1-hour prompt cache
The new promptCacheTtl setting keeps your main conversation's prompt cache alive for a full hour, while subagents stay at 5 minutes. Long sessions with thinking gaps stop re-paying full input price on every turn — it works for API-key and Bedrock/Vertex users.
Curate your /model picker
modelPicker lets you replace or extend the built-in /model list with your own ordered, labeled models — any id spelling, including Vertex and Bedrock ids. Pin the two or three models you actually switch between and drop the rest.
Sign in without an API key
A keyless option under /login lets orgs that ban API keys onboard by signing in with an Anthropic Console account. It pairs with a new modelPricing setting, so /cost, the status line, and telemetry bill at your contracted rates instead of list price.
Catch runaway loops
/usage now shows a Loops breakdown — run count, total tokens, tokens per run, and last run for each /loop task — so a chatty background loop quietly burning tokens is easy to spot. Idle /loop wake-ups also fold into a single terminal line.
A 75 MB binary, lighter sessions
The native binary is now zstd-compressed to about 75 MB instead of 340 MB on Linux x64, and on-demand code loading trims roughly 40-70 MB of memory per session. Faster installs and auto-updates, lighter long-running sessions.
No more silent 10-minute hangs
When the API never starts a response, requests now time out after ~3 minutes, retry once, then surface 'API Error: No response from API' instead of hanging. Remote MCP servers in -p and SDK sessions also auto-reconnect after a dropped connection.
Arch users: startup crash fixed
v2.1.245 fixes a crash on startup for distros shipping glibc 2.44 — Arch, CachyOS, and Fedora Rawhide. The same run also relabels Sonnet 5's $2/$10-per-Mtok rate as its standard list price rather than a limited-time promo.