Multivariate override editor hides the identity's override value (shows the flag's control value instead)

[talissoncosta]

Description

When an identity has a single-value override on a feature that is later made multivariate, the "Edit User Feature" modal stops showing the identity's override value. In multivariate mode the editor renders only the flag's options as radios (control + each variant), so an override whose value is not one of those options has nowhere to appear. The control row shows the environment's control value, so the identity looks like it is on the default.

The override is intact and the SDK serves it correctly, so this is a display issue in the override editor. If the user saves that modal, the displayed control value is written over the override, so the value can be lost on save.

Steps to reproduce

1. Create a standard flag with control value ENV_DEFAULT.
2. Set an identity override on it to MY_OVERRIDE.
3. On the Features page, make the feature multivariate: update the control value and add a variant VARIANT_A.
4. Open that identity and open the "Edit User Feature" modal for the flag.

Expected

The editor shows the identity's override value (MY_OVERRIDE).

Actual

The editor shows the flag's control value selected. MY_OVERRIDE is not shown anywhere in the modal. The identities list still shows MY_OVERRIDE, and the SDK still serves it.

Screenshots

• Identities list (correct): the feature row shows the override MY_OVERRIDE.
• Edit User Feature modal (the bug): only ENV_DEFAULT (selected) and VARIANT_A are shown; MY_OVERRIDE is absent.
• Features page: the flag's control value and variation as configured.

Impact

Display only, no data lost while viewing. Risk: saving the modal overwrites the override with the displayed control value.

Root cause (initial)

frontend/web/components/modals/create-feature/tabs/FeatureValueTab.tsx passes the environment control value as controlValue to VariationOptions in select mode (changed in #6585, which fixed #6582). The multivariate override editor only models "control or a variant", so a free-form override value has no representation.

Proposed behaviour

Show the identity's own override value in the editor, read-only, with a warning like "This identity override contains a value that is not one of this flag's variations. We recommend changing it.", and offer the variations for selection so the user can migrate it. Guard against a save silently overwriting the override.

References

• Confirmed on staging.
• Related: Unexpected behaviour creating identity overrides for control value of MV features #4599, Cannot create identity override for control values in a multivariate feature #5263, Editing an identity override for a multivariate feature doesn't show all variations #6582, fix: display correct control value in identity override variation list #6585, Segment UI only renders first top-level rule, silently drops additional rules #7254