Deploying the internal gateway was a manual build/pack/scp/npm-i/pm2-restart sequence with no record of what landed and no proof it served traffic. On 2026-08-14 that shipped a package built from a branch predating #10373: the process came up, health said 'healthy', and every request returned 502 until a human hit it.
scripts/ops/deployCanary.ts holds the policy as pure functions — refuse an artifact that is not traceable to the release line (reusing #10427), and grade the deploy on health PLUS at least one real completion. Zero probes fails: 'no probe ran' must never read as 'everything is fine', which is exactly how a broken egress path hides behind a green health check. Remote steps are argv arrays, never shell strings (Hard Rule #13), ordered so the rollback anchor is captured before the install overwrites it.
scripts/ops/deploy-canary.mjs performs the side effects, supports --dry-run, and prints the rollback command when the smoke fails.
Closes#10429
