## Problem
Cookie banner keeps re-prompting GDPR users who denied consent or made a
partial opt-out via Privacy Settings — they can't get rid of it.
Reported by Christian Gedde-Dahl (Front SU-362240, mygame.no) and a
Supabase support engineer independently.
The March fix for FE-2648 handled the accept case — users got their
banner dismissal stomped when GTM's Usercentrics integration migrated
localStorage from `uc_settings` to `ucData`/`ucString`. But that fix
only recognized uniformly-accepted `ucData`, so any other shape
(deny-all, essentials-plus-some-tracking, partial opt-out via the
Privacy Settings modal) fell through and was treated as "no prior
decision." Banner re-prompts on every page load.
Christian's and his colleague's `ucData.consent.services` showed 13
services accepted (essentials + functional) and 4 tracking services
denied — the shape you get from toggling off the Marketing category in
Privacy Settings. Our detection ignored it.
## Changes
- `detectPriorConsent` now returns a discriminated union — `null`, `{
kind: 'uniform-accept' }`, or `{ kind: 'decisions'; decisions }` — so we
restore per-service state faithfully instead of flattening to deny-all.
- Parse `uc_settings` for the fast cross-app nav case. The old fallback
treated `uc_user_interaction === "true"` as uniform-accept, which
silently upgraded deny users (GDPR violation waiting to happen). Now the
flag is just a gate confirming the user actually interacted, and we read
real decisions from `uc_settings.services[]`.
- Extracted the post-init orchestration from `initUserCentrics` into
exported `applyPriorDecisionToSDK(UC, initialUIValues, priorDecision)`
so it's unit-testable without mocking the dynamic SDK import.
- Added a coverage cross-check: if the Usercentrics ruleset has a
non-essential service that isn't in the user's stored decisions, force a
re-prompt rather than silently defaulting the new service. Essentials
are skipped because the SDK forces them on regardless.
- Everything fails closed on partial `ucData` / `uc_settings`
corruption. Cherry-picking the valid subset would bias toward
over-consent, which is the worst-direction bias in this domain.
## Testing
27 unit tests covering `detectPriorConsent` parsing (both `ucData` and
`uc_settings` paths, fail-closed on malformed or partially-corrupt
blobs, combined scenarios) and `applyPriorDecisionToSDK` orchestration
(uniform accept, decisions with full coverage, uncovered-non-essential
compliance guard, essentials-only negative control, null fallthrough,
SDK-already-consented passthrough).
Can't fully repro on staging — CSP blocks GTM on preview, so the
`ucData` migration never fires. Same limitation as the original FE-2648
fix. Will verify in production post-merge by asking Christian to reload
and watching support ticket volume.
Reviewed twice by Codex with a full iteration between passes; final pass
found no functional blockers.
GROWTH-790
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Bug Fixes**
* Fail-closed validation for stored consent data: malformed, partial, or
missing entries now yield null and avoid unsafe restoration.
* Improved precedence and fallback so corrupt prior data won’t
incorrectly restore consent.
* **Refactor**
* Consent detection now returns richer prior-decision results (uniform
accept, per-service decisions, or null).
* Applying prior decisions to the SDK uses stricter coverage checks
before restoring per-service consent.
* **Tests**
* Expanded tests covering varied stored-consent shapes, gating rules,
precedence, recovery, and SDK application behavior.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
## Problem
Follow-up to #44252. The previous fix handled the case where the user
waits on the page after accepting (GTM writes `ucData`), but there's a
second scenario: if the user accepts and navigates to another app
quickly (before GTM finishes), `ucData` hasn't been written yet. The SDK
on the new app overwrites `uc_user_interaction: "true"` with `"false"`
and shows the banner again.
## What changed
`hasPreviousConsentInUcData` is now `detectPriorConsent` and checks two
signals before `UC.init()` overwrites them:
1. **Slow navigation** (existing): `ucData` contains all services with
`consent: true`
2. **Fast navigation** (new): `uc_user_interaction` is `"true"` — the
SDK on the previous app wrote this but GTM hasn't had time to replace it
yet
Also adds unit tests covering both scenarios, edge cases (empty
services, malformed JSON, mixed signals), and the combined behavior.
## Testing
- 13 unit tests for `detectPriorConsent()` covering all localStorage
state combinations
- Can't fully reproduce on staging previews (CSP blocks GTM), verified
root cause via production console monitoring
Closes FE-2648
Sean Oliver