chore: Add maintenance mode flag

[kyle-ssg]

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• I have read the Contributing Guide.
• I have added information to docs/ if required so people know about the feature.
• I have filled in the "Changes" section below.
• I have filled in the "How did you test this code" section below.

Changes

Adds maintenance_mode flag as an option to turn on maintenance mode

How did you test this code?

Turned on the flag for the staging environment

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Project	Deployment	Actions	Updated (UTC)
flagsmith-frontend-preview	Ready	Preview, Comment	May 6, 2026 9:48am
flagsmith-frontend-staging	Ready	Preview, Comment	May 6, 2026 9:48am

1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Ignored		May 6, 2026 9:48am

[github-actions]

Docker builds report

Image	Build Status	Security report
ghcr.io/flagsmith/flagsmith-api-test:pr-7435	Finished ✅	Skipped
ghcr.io/flagsmith/flagsmith-e2e:pr-7435	Finished ✅	Skipped
ghcr.io/flagsmith/flagsmith-api:pr-7435	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith-private-cloud:pr-7435	Finished ✅	Results ✅
ghcr.io/flagsmith/flagsmith-frontend:pr-7435	Finished ✅	Results ✅

[chromatic-com]

Important

Testing in progress…

🟢 UI Tests: 284 tests unchanged
⏳ UI Review: Comparing 142 stories…
Storybook Publish: 142 stories published

[chromatic-com]

Tip

All tests passed and all changes approved!

🟢 UI Tests: 284 tests unchanged
🟢 UI Review: 142 stories published -- no changes
Storybook Publish: 142 stories published

[github-actions]

Playwright Test Results (oss - depot-ubuntu-latest-16)

 11 passed

Details

 11 tests across 8 suites
 23.9 seconds
 f622be2
 🔄 Run: #16544 (attempt 1)

Playwright Test Results (oss - depot-ubuntu-latest-arm-16)

 11 passed

Details

 11 tests across 8 suites
 50.2 seconds
 f622be2
 🔄 Run: #16544 (attempt 1)

Playwright Test Results (private-cloud - depot-ubuntu-latest-arm-16)

 17 passed

Details

 17 tests across 14 suites
 1 minute, 5 seconds
 f622be2
 🔄 Run: #16544 (attempt 1)

Playwright Test Results (private-cloud - depot-ubuntu-latest-16)

 2 passed

Details

 2 tests across 2 suites
 42.2 seconds
 f622be2
 🔄 Run: #16544 (attempt 1)

[github-actions]

Visual Regression

16 screenshots compared. See report for details.
View full report

[matthewelwell]

@claude review

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[matthewelwell]

@claude review

[claude]

LGTM — straightforward additive feature-flag check using the existing Utils helper.

Extended reasoning...

Overview

This PR makes a single, small change to frontend/web/components/App.js: it adds Utils.getFlagsmithHasFeature('maintenance_mode') as an additional condition that triggers the <Maintenance /> screen, alongside the existing Project.maintenance, this.props.error, and !window.projectOverrides checks. The change is a 6-line additive modification with no other touched files.

Security risks

None apparent. The flag is read client-side via the existing Flagsmith feature-flag helper and only controls whether the maintenance UI is rendered — it does not affect authentication, authorization, data exposure, or any sensitive code path. Worst-case behavior of a misconfigured flag is showing the maintenance screen to users, which is the intended behavior.

Level of scrutiny

Low. This is a frontend-only chore-level change that follows an established pattern (toggling rendering based on a feature flag via Utils.getFlagsmithHasFeature). The author tested by enabling the flag on staging, all CI checks pass (Playwright OSS + private-cloud, Chromatic visual regression, Docker builds), and there is no logic complexity beyond an added boolean term in an OR expression.

Other factors

The author has explicitly requested review twice and no bugs were surfaced by the bug-hunting system. The change is self-contained, easy to revert, and has a clear, well-scoped intent.