Wire blue-green rollout strategy into deployment update flow

[temma02]

Description

BlueGreenSwitcher and RolloutEngine are fully tested in apps/backend/tests/deployment/rollout-strategy.test.ts but are not used in the live update flow. Deployments currently do a hard cutover, which causes brief downtime on updates.

Requirements and context

• Must be secure, tested, and documented where applicable
• Should stay reviewable and fit the current monorepo structure
• Relevant files: apps/backend/tests/deployment/rollout-strategy.test.ts, apps/backend/src/services/deployment-update.service.ts, apps/backend/src/services/vercel.service.ts

Suggested execution

• Create branch: issue-024-wire-blue-green-rollout-strategy
• Keep changes scoped to the issue and reference the task IDs in the PR

Implement changes

• Integrate RolloutEngine into DeploymentUpdateService.executeUpdatePipeline
• Use BlueGreenSwitcher to manage standby/active Vercel project aliases during promotion
• Expose a canaryPercent field in the update record so operators can monitor traffic split

Test and commit

• Add update service tests for: successful promotion, auto-rollback on error rate spike, manual rollback
• Include a sequence diagram in the PR description showing the traffic shift
• Edge case: Vercel alias update fails mid-switch — revert to previous alias automatically

Example commit message

feat(deployments): integrate blue-green rollout into update pipeline

Guidelines

• Prefer small, reviewable PRs
• Keep naming and data contracts consistent with the spec docs

[dot-enny]

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Hi, i think i can handle this.

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[Ekenesamuel8]

@Ekenesamuel8 has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

I will like to work on this task

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[LaahAbba]

@LaahAbba has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Hi my name is Abba and I'm a full stack develop I'll like to work on this issue because It picks my interest and Ive got experience with similar projects I'll have it solved in 24 hours or less

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[drips-wave]

Congratulations, @Ekenesamuel8! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on April 29, 2026.

🧑‍💻 @Ekenesamuel8: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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