fix(cli): don't assume newest deployment is live in promote resolution

[kristof-siket]

Why

resolveCurrentLiveDeploymentId fell back to deployments[0] (the newest deployment) when no authoritative live signal was available (app.liveDeploymentId, the provider live flag, or local known-live state):

return deployments[0]?.id ?? null;

During app promote, this made a freshly created candidate look like it was already live, so promote emitted "The selected deployment is already live for this app." and skipped the endpoint rebind. An app whose live pointer had been cleared (e.g. its live deployment was stopped) therefore never got re-bound — every subsequent deploy hit the same false "already live" and left the app unreachable.

This was the second half of a production incident on 2026-07-20: after the live deployments of build-runner/github-webhook were stopped (clearing latestDeploymentId), each CI redeploy's promote step read the null pointer, hit this fallback, and skipped the rebind — turning a transient stop into a ~1h outage.

What

Return null instead of guessing the newest. "Unknown live deployment" now means not already-live, so promote proceeds and rebinds the endpoint.

Tests

• New: promote rebinds instead of assuming the newest deployment is live when there is no authoritative live signal.
• Full app-controller suite green.

🤖 Generated with Claude Code

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Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 7cc458ae-18bd-45ab-9fb5-8301d556bac8

📥 Commits

Reviewing files that changed from the base of the PR and between c8b2562 and 6df1982.

📒 Files selected for processing (1)

• packages/cli/src/controllers/app.ts

Walkthrough

The app controller no longer assumes the newest deployment is live when no authoritative live signal exists; it returns null instead. A new test verifies that runAppPromote promotes the requested deployment in this situation and returns no warnings.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly matches the main change: avoiding the newest-deployment fallback in promote resolution.
Description check	✅ Passed	The description accurately explains the bug, the fix, and the regression test.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/promote-live-resolution-no-newest-fallback

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch fix/promote-live-resolution-no-newest-fallback

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[kristof-siket]

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