Feat/built in feature flag

[arxja]

Summary by CodeRabbit

• New Features
  • Added feature-flag support for controlling application functionality through configuration.
  • Added support for a client-configured demo mode.
  • Added safeguards to prevent client-side access to server-only feature settings.
  • Added consistent handling for checking whether features are enabled and retrieving configured values.

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 3fa52bc8-15e6-4599-bc57-c23ab5062ce9

📥 Commits

Reviewing files that changed from the base of the PR and between caf4091 and ed27721.

📒 Files selected for processing (6)

• .github/workflows/ci.yml
• docs/guides/feature-flag.md
• hooks/useFeatureflags.ts
• lib/config/config-client.ts
• lib/config/index.ts
• lib/feature-flags.ts

📝 Walkthrough

Walkthrough

Adds typed feature-flag utilities with client/server access rules, requires NEXT_PUBLIC_DEMO_MODE in client configuration, and exposes demo mode through a memoized client-side React hook.

Changes

Feature flag configuration

Layer / File(s)	Summary
Flag registry and configuration contracts lib/feature-flags.ts, lib/config/index.ts, lib/email/index.ts	Defines supported feature flags, adds the required NEXT_PUBLIC_DEMO_MODE client setting, and updates the commented email enablement reference.
Flag access utilities lib/feature-flags.ts	Adds override-aware enablement checks and configuration value access with client-side restrictions and development warnings.
Client feature flag hook hooks/useFeatureflags.ts	Adds a client-only hook that memoizes the demoMode flag and an empty UI configuration object.

Estimated code review effort: 3 (Moderate) | ~20 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title matches the main change: adding built-in feature-flag support.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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 feat/built-in-feature-flag

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[coderabbitai]

Actionable comments posted: 5

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@hooks/useFeatureflags.ts`:
- Around line 16-18: Update the demoMode value in useFeatureflags to normalize
clientConfig.NEXT_PUBLIC_DEMO_MODE to a boolean by reusing the shared enablement
helper or checking equality with "true"; ensure the hook’s result type exposes
demoMode as boolean so the string "false" cannot enable demo behavior.
- Line 3: Update the client-facing hooks/useFeatureflags.ts import so it no
longer references the server-inclusive `@/lib/config` module. Split or use the
existing client-safe configuration module, ensuring clientConfig remains
available without importing serverConfig or invoking getServerConfig() in the
"use client" module graph.

In `@lib/config/index.ts`:
- Line 35: Update the NEXT_PUBLIC_DEMO_MODE schema and configuration boundary to
accept only "true" or "false" and normalize the value to a boolean. Ensure
useFeatureFlags() exposes the same boolean result used by
isEnable("NEXT_PUBLIC_DEMO_MODE"), preserving consistent component conditionals.

In `@lib/feature-flags.ts`:
- Around line 38-56: Update isEnable so the client/server restriction is
evaluated before the overrides branch: on the client, only flags starting with
"NEXT_PUBLIC_" may use overrides, while server-only flags must return false.
Preserve override priority for server-side calls and the existing client-safe
configuration behavior.
- Around line 13-18: Align the FEATURE_FLAGS entry
NEXT_PUBLIC_FEATURE_NEW_DASHBOARD with the clientConfig validation by adding the
corresponding field to clientSchema, including the appropriate type and
optionality used for client feature flags. Alternatively, remove the flag from
FEATURE_FLAGS until schema support is wired, ensuring isEnable() cannot
reference an unvalidated configuration key.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: e8f014f4-590e-48aa-8eb0-7751249c8c0b

📥 Commits

Reviewing files that changed from the base of the PR and between eadccfb and caf4091.

📒 Files selected for processing (4)

• hooks/useFeatureflags.ts
• lib/config/index.ts
• lib/email/index.ts
• lib/feature-flags.ts