Feature Flag Stale Cleanup Auditor

---
name: feature-flag-stale-cleanup-auditor
description: Audits feature flags against your codebase and plans their cleanup - finds release flags 100% on or off for weeks, rollouts stuck at a partial percentage, experiments that never ended, expired, archived and unreferenced flags, keys used in code but missing from the flag service (or misspelled), staging-production drift and flags without an owner. Lists every file:line to change with effort. Includes an offline stdlib Python scanner.
---

# Feature Flag Stale Cleanup Auditor

You help engineering teams pay down feature flag debt. Flags are cheap to add and nobody removes them: a release flag sits at 100% for months with the old code path still compiled in, a rollout stops at 25% and half the users get a different product, an A/B test runs for half a year, and a key misspelled in code quietly returns the SDK default so a "launched" feature is never shown. You compare the flag inventory with the code, decide for every flag whether to remove it (keeping the ON or the OFF path), finish it, decide it or archive it, and hand back a cleanup plan with the exact references to change.

You work from an exported or hand-written flag inventory and the source folders you are given. You do not change flags in the flag service: the team archives a flag only after the code change is deployed everywhere.

## Files in this skill

- `scripts/flag_audit.py` - reads a flags JSON (key, type release / experiment / ops / kill-switch / permission, owner, created, expires, archived, per-environment on / rollout / updated) and scans source folders (.ts .tsx .js .jsx .py .go .rb .java .kt .cs .php .swift .vue .svelte; skips node_modules, dist, vendor) for SDK calls, string literals and `flags.camelCase` properties; reports FF01-FF14 and a ranked cleanup plan with file:line references and effort (Python 3.8+ standard library only)
- `references/flag-lifecycle-and-removal.md` - flag types and their expected lifetime, how to remove a flag safely (keep ON / keep OFF), exporting inventories from common flag services, and policies that stop flag debt coming back
- `references/checks-and-codes.md` - every finding code, its severity and what to do, plus the input format
- `templates/cleanup-ticket.md` - the cleanup ticket / PR description for each flag
- `examples/flags.json` - nine flags of a web shop (release, experiment, kill-switch, permission, archived)
- `examples/src/checkout.ts`, `examples/src/Header.tsx`, `examples/src/search.py` - code using them, including a misspelled key, a key that does not exist and a key built at runtime
- `examples/cleanup-report.md` - the real scanner output on the example

## Workflow

### 1. Collect the inventory and the code
Ask which flag service they use and for an export of all flags with type, owner, creation date, expiry or ticket, and per-environment state (on/off, rollout percentage, last change). Map it into a JSON like `examples/flags.json` (see the reference for LaunchDarkly, Unleash, Flagsmith, GrowthBook and ConfigCat field names). Ask for the repositories or folders that read flags and the name of their flag-check function if it is not a common SDK call.

### 2. Run the scanner
```
python3 scripts/flag_audit.py examples/flags.json examples/src
python3 scripts/flag_audit.py flags.json web/src api/app --today 2026-11-05 --stale-days 21
python3 scripts/flag_audit.py flags.json src --call featureOn --call can
python3 scripts/flag_audit.py flags.json src --json
python3 scripts/flag_audit.py --self-test
```
Exit 0 = no high findings, 1 = high findings, 2 = bad input. Without a shell, search the code for each key (`git grep -n "<key>"`) and apply the rules in `references/checks-and-codes.md` by hand.

### 3. Read the result
- High first: FF01 keys in code that the flag service does not know (typos read the default, so the feature is effectively off) and FF14 archived flags still in code.
- Medium: FF02 fully on and FF03 fully off for longer than the stale window, FF12 stuck rollouts, FF09 long experiments, FF05 expired, FF08 production ahead of staging.
- Low/info: unreferenced flags (check other repos first), missing owner or expiry, long-lived flags (kill switches, permissions) listed but not judged stale, keys built at runtime that search cannot find.

### 4. Plan the cleanup
Work down the plan table: fix typos first, then remove flags with few references (effort S) to build momentum. For "keep ON" delete the check and the OFF branch and any code only it used; for "keep OFF" delete the guarded code. Stuck rollouts and experiments need a decision from the owner before code changes. Fill `templates/cleanup-ticket.md` per flag.

### 5. Deliver
Return the verdict, the ranked plan with owners and file:line lists, the tickets, and two or three policy suggestions (expiry dates on every temporary flag, a monthly cleanup slot, a lint rule or CI check that fails on unknown keys).

## Example result
Three high findings: `new-checkout-flow-v3` is read in checkout.ts but does not exist, `recs_carousel` in search.py is a typo of `recs-carousel` - so the carousel that is "100% on" for 170 days has never been shown - and the archived `legacy-pdf-invoices` is still checked. `new-checkout-flow` has been 100% on for 86 days and expired in September (2 references, keep ON), the 2025 holiday banner has been off for 303 days (keep OFF), `search-v2` is stuck at 25% for 63 days, and the pricing experiment has run 199 days. `dark-mode` is on in production but off in staging. Kill switch and permission flags are kept.

## Rules

- Never recommend removing a kill switch, ops or permission flag because it is old; they are long-lived by design.
- A flag with no references in the scanned folders may be used elsewhere (mobile apps, other services, config); say so before suggesting to archive it.
- Remove code first, deploy, then archive the flag in the service - never the other way round.
- A stuck rollout or a running experiment needs the owner's decision; do not pick the winner for them.
- Treat `today` and the stale window as inputs; say which values you used.
FILE:references/flag-lifecycle-and-removal.md
# Flag lifecycle and safe removal

## Flag types and expected lifetime
| Type | Purpose | Expected life | Done when |
|---|---|---|---|
| release | hide unfinished work, roll out gradually | days to a few weeks after 100% | 100% everywhere and stable for the stale window |
| experiment | A/B or multivariate test | the test duration (2-6 weeks typical) | a decision is made |
| ops | operational switch (cache on/off, batch size) | long | rarely; review yearly |
| kill-switch | turn off a risky dependency fast | permanent | never by age |
| permission | entitlement, beta access, plan feature | permanent (or move to the billing/entitlement system) | product decision |

## Removing a flag safely
1. Confirm the state with the owner: fully on (keep ON) or fully off (keep OFF), in every environment and every service that reads it.
2. Find all references (the scanner's list plus `git grep -n "<key>"` in other repos, mobile apps, infrastructure config, analytics dashboards and tests).
3. Keep ON: replace the check with the ON branch, delete the OFF branch, then delete code only the OFF branch used (old components, endpoints, styles, migrations guards). Keep OFF: delete the guarded code and anything only it used.
4. Delete flag-specific tests and fixtures; keep tests of the behaviour that stays.
5. Deploy to every environment. Mobile apps: wait until old app versions that read the flag are below your support threshold.
6. Then archive the flag in the flag service (archive, do not delete, so the history stays).
7. Close the ticket with the PR links.

## Common traps
- Typos and renamed keys: the SDK returns the default for unknown keys without an error, so code reading `recs_carousel` never sees `recs-carousel`. A CI check that compares literal keys with the inventory catches this.
- Archiving first: an archived flag returns the default everywhere still reading it - often the OFF path, i.e. an instant rollback of a launched feature.
- Stuck rollouts: 25% for two months means two products to support and test; finish or roll back.
- Experiments without an end date keep skewing metrics and analytics events.
- Keys built at runtime (`"export-format-" + region`) cannot be found by search; keep a constants file listing every possible key.

## Exporting the inventory
- LaunchDarkly: REST `GET /api/v2/flags/{projectKey}?summary=0` -> `key`, `creationDate` (ms), `temporary`, `archived`, `maintainerId`/`_maintainer`, `tags`, `environments.<env>.on`, `.lastModified`, rollout weights in `fallthrough.rollout.variations` (weight/1000 = percent). Map `temporary: false` to `permanent: true`.
- Unleash: `GET /api/admin/projects/<p>/features` -> `name`, `type` (release, experiment, operational, kill-switch, permission), `createdAt`, `stale`, `environments[].enabled`, gradual rollout strategy `parameters.rollout`.
- Flagsmith: `/api/v1/projects/<id>/features/` + per-environment `featurestates` (`enabled`, `updated_at`), percentage via segment overrides.
- GrowthBook: `/api/v1/features` -> `id`, `owner`, `dateCreated`, `archived`, `environments.<env>.enabled`, rollout rule `coverage` (0-1 -> percent).
- ConfigCat: Management API settings + values per environment; percentage options give the rollout.
- In-house config (YAML/JSON): one entry per flag; add created/owner/expires by hand from git blame.

## Policies that keep flag debt down
- Every temporary flag gets an owner, a ticket and an expiry date when it is created.
- Cleanup is part of the definition of done: the removal ticket is created with the flag.
- A monthly 30-minute flag review using this audit; a cap on active release flags per team.
- CI: fail on keys not in the inventory; warn on expired flags still referenced.
FILE:references/checks-and-codes.md
# Checks and finding codes

| Code | Severity | Check | What to do |
|---|---|---|---|
| FF01 | high | a flag-check call (isEnabled, variation, useFlag, is_enabled ...) uses a key that is not in the inventory; a close match is suggested (typo, `_` vs `-`) | fix the key or create the flag; until then the SDK returns the default value |
| FF02 | medium | release flag at 100% in the primary environment for `stale_days` or more | remove the flag, keep the ON path |
| FF03 | medium | release or experiment flag off / 0% in the primary environment for `stale_days` or more | remove the flag and the guarded code, or decide to launch |
| FF04 | low | no reference in the scanned files | check other repos and services; archive if unused |
| FF05 | medium | `expires` date passed (temporary flags) | remove or agree a new date |
| FF06 | info | ops, kill-switch, permission (or `permanent: true`) flag - not judged stale | review yearly |
| FF07 | low | no owner | assign one |
| FF08 | medium | primary environment ahead of staging/qa/test/dev, or no state for the primary environment | align environments |
| FF09 | medium | experiment older than `experiment_max_days` | decide, ship the winner, remove |
| FF10 | info | flag key built at runtime (variable, concatenation, template string) | use literal keys or a constants file |
| FF11 | low | temporary flag without `expires` | set an expiry |
| FF12 | medium | release rollout between 1 and 99% unchanged for `stale_days` | finish (100%) or roll back, then remove |
| FF13 | medium | key defined twice in the inventory | merge |
| FF14 | high | flag archived in the service but still referenced in code | remove the references |

## Verdict
- **N high finding(s)** when FF01/FF14 exist; else **N flag(s) ready to remove**; else **no stale flags**.

## Plan actions (in this order)
remove code (archived) -> remove, keep ON -> remove, keep OFF -> finish rollout -> decide experiment -> archive (no references). Within an action, flags with more references first. Effort: S 1-2 references, M 3-6, L 7+.

## How references are found
1

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