add-studio-feature-flag

name	add-studio-feature-flag
description	Adds a NeMo Studio (Vite) feature flag end-to-end: typed definition, runtime injection mapping, FastAPI build env markers, and optional Helm config. Use when the user asks for a new feature flag, VITE_FF_ variable, studio.feature_flags setting, toggling UI behind a flag, or preview/boolean flags for Studio.

Add a Studio feature flag

Studio flags live in web/packages/studio and are wired into the FastAPI Studio bundle via marker replacement at runtime. Follow every step that applies so local dev, FastAPI builds, and cluster deploys stay consistent.

For broader Studio context, see .cursor/skills/studio-dev/SKILL.md.

1. Choose flag shape

Helper	TypeScript value	Use when
previewFlag(envVar, default?)	true | 'preview' | false	User-facing features that may show the Early Preview badge ('preview')
booleanFlag(envVar, default?)	boolean	Internal toggles (no preview mode)
stringFlag / numberFlag	string / number	Rare; see web/packages/studio/src/constants/featureFlags/utils.ts

Preview behavior: true and 'preview' are both truthy for if (featureFlags.myFlag). Only 'preview' triggers FeatureFlagBadge (see step 6).

Naming

• Env var: VITE_FF_<SCREAMING_SNAKE_CASE>
• flagDefinitions key: camelCase (e.g. jobQueueEnabled)
• studio.feature_flags / config_path: snake_case (e.g. job_queue_enabled)

2. Register the flag (TypeScript)

File: web/packages/studio/src/constants/featureFlags/featureFlags.ts

Add one entry to flagDefinitions:

jobQueueEnabled: previewFlag('VITE_FF_JOB_QUEUE_ENABLED'),
// or
jobQueueEnabled: booleanFlag('VITE_FF_JOB_QUEUE_ENABLED'),

Alphabetical order with sibling keys is preferred.

Consume

import { featureFlags } from "@studio/constants/featureFlags";

if (featureFlags.jobQueueEnabled) {
  // enabled (true or 'preview')
}

3. Optional: environment.ts re-export

File: web/packages/studio/src/constants/environment.ts

If the codebase prefers SOME_FEATURE_ENABLED constants (see existing MEMBERS_ENABLED, SECRETS_ENABLED, etc.), add:

export const JOB_QUEUE_ENABLED = featureFlags.jobQueueEnabled !== false;

Use this only when it matches an established pattern for that area of the app.

4. Runtime injection (FastAPI Studio service)

File: services/studio/src/nmp/studio/env_mappings.py

Add an EnvMapping in ENV_MAPPINGS (keep the feature-flag block grouped):

EnvMapping(
    marker="STUDIO_UI_VITE_FF_JOB_QUEUE_ENABLED",
    config_path="studio.feature_flags.job_queue_enabled",
    default="false",
),

• marker is always STUDIO_UI_ + the Vite env name (VITE_FF_...).
• default is a string ("true", "false", or "preview" for preview flags).

5. FastAPI build env markers (parity)

File: web/packages/studio/env/.env.fastapi

Add a line so the built bundle contains the placeholder the Studio service replaces:

VITE_FF_JOB_QUEUE_ENABLED=STUDIO_UI_VITE_FF_JOB_QUEUE_ENABLED

The file header requires parity with env_mappings.py—do not skip this for flags used in FastAPI mode.

6. Local development

Update both files so the sample stays in lockstep with the feature-flag inventory — devs copy the sample to bootstrap .env.dev.local, and a missing entry means the flag silently falls back to its default.

File: web/packages/studio/env/.env.dev.local.sample (always — committed reference)

Add the flag in the # Feature Flags (VITE_FF_* prefix) block, alphabetized with sibling VITE_FF_* lines. Use the value a new developer should start with (usually the same as the default in env_mappings.py):

VITE_FF_JOB_QUEUE_ENABLED='false'

File: web/packages/studio/env/.env.dev.local (only if you want it on for your own machine — gitignored)

VITE_FF_JOB_QUEUE_ENABLED='true'
# or for preview badge behavior:
VITE_FF_JOB_QUEUE_ENABLED='preview'

7. Gate UI and routes

• Routes: lazy imports / children arrays in web/packages/studio/src/routes/index.tsx, or conditional wrappers—mirror existing flags (e.g. membersEnabled, secretsEnabled).
• Nav: WorkspaceSideNav and similar—search for featureFlags. patterns.
• Preview badge: For previewFlag entries, add <FeatureFlagBadge flag="jobQueueEnabled" /> next to the feature title when appropriate (web/packages/studio/src/components/FeatureFlagBadge/index.tsx).

8. Helm / platform config (deployed environments)

Under studio.feature_flags in values (e.g. deploy/helm/values/ci/dev-values.yaml), add the snake_case key with string value true, false, or preview as needed.

Global settings schema may need updating if the new key is not yet defined—follow how existing studio.feature_flags.* keys are declared in the repo.

Checklist

Copy and track:

• flagDefinitions in featureFlags.ts (correct helper + defaults)
• EnvMapping in env_mappings.py
• VITE_FF_*=STUDIO_UI_VITE_FF_* line in env/.env.fastapi
• env/.env.dev.local.sample updated (committed reference for new devs)
• Local env/.env.dev.local (only if developers need the flag on for their own machine)
• UI/route/nav gated with featureFlags.<key> or environment.ts constant
• FeatureFlagBadge if the flag uses previewFlag and should show Early Preview
• Helm / values or docs updated for environments that should see the flag
• pnpm typecheck (from web/packages/studio or monorepo Studio package) after TS edits

Removing a flag (reference)

1. Remove all usages.
2. Remove from flagDefinitions, env_mappings.py, .env.fastapi, Helm values, and samples.
3. Remove any environment.ts export.