Full Changelog: v4.2.0...v4.2.1

Full Changelog: v4.1.0...v4.2.0

What changed

OpenRouter is now the default transport. One key reaches every model (Nano Banana + GPT-5 Image), separate rate bucket, no free-tier quota surprises.

Automatic fallback on transient failures. When the preferred transport hits RATE_LIMITED, NETWORK_ERROR, AUTH_INVALID, or AUTH_EXPIRED, nanaban silently retries on the next available transport. Success envelope gains a fallbacks audit trail. --via <t> still pins a single route when you want it.

Error envelopes now include hint — every error code carries an actionable recovery suggestion, so agents can self-correct instead of bailing out.

Why

Agents were dying on Gemini 429s even when a valid OpenRouter key was configured, because the router only tried one transport. Agents don't read intent from stack traces — they act on exit codes and envelopes. The whole point of configuring both keys is resilience; now you actually get it.

Upgrade

npm install -g nanaban@4.1.0

Agents

Set OPENROUTER_API_KEY as primary; optionally also GEMINI_API_KEY for local failover. Run nanaban agent-info for the machine-readable manifest — fallback policy, retry codes, envelope shapes are all there.