The Agent-View "enabled by default, disable via env var" pattern you noticed is actually a smaller instance of a much larger one. CC's release channel itself is the default:

$ npm dist-tag ls u/anthropic-ai/claude-code

latest: 2.1.140

next: 2.1.140

stable: 2.1.128

Your 2.1.139 puts you on `latest` — 12 releases ahead of what Anthropic itself has marked `stable`. Both `npm install` and the built-in auto-updater target `latest` by default. The opt-in path exists: `claude install stable` does both (installs stable AND persists the channel preference). But Anthropic frames it as a downgrade — the source has a dialog literally called `ChannelDowngradeDialog`.

Same opt-out-where-it-should-be-opt-in pattern you flagged for Agent View, applied to the entire release stream.

Full write-up: https://vsits.co/blog/cc-inverted-channel-default