- New `omnigraph update` subcommand: GitHub Releases API → archive download
→ SHA256 verification → atomic POSIX rename of both binaries.
- Detects Homebrew installs and short-circuits with a hint to run
`brew upgrade ModernRelay/tap/omnigraph`.
- Channels: `--channel stable` (default) or `edge`. `--check` for
check-only, `--yes` to skip the confirmation prompt.
- Best-effort startup version check (24h cached at
`~/.cache/omnigraph/update-check.json`) with one-line stderr notice.
Cache is refreshed via a detached `__refresh-update-cache` subprocess so
the foreground command never blocks on the network. Suppression: CI,
`OMNIGRAPH_NO_UPDATE_CHECK=1`, non-TTY stdout, and `version`/`update`
subcommands.
- Integration tests use an in-process raw-TCP HTTP fixture (no extra
dev-deps) and override `OMNIGRAPH_UPDATE_API_BASE` /
`OMNIGRAPH_UPDATE_DOWNLOAD_BASE` to keep the suite hermetic.
- Docs: `install.md`, `cli.md`, `cli-reference.md` updated.
Co-Authored-By: Ragnor Comerford <ragnor.comerford@gmail.com>
