Problem

Northern Sky Raid Tools can also be set to put nicknames on DandersFrames frames. When its Global Nicknames + DandersFrames toggles are on, it hard-overwrites DF:GetUnitName with its own resolver — so with both addons managing names, the displayed name silently depends on load order and whichever addon refreshed last. Users get no signal that the two are fighting.

(Discussed beforehand — this implements the approach you signed off on.)

Solution — entirely DF-side

NSRT is never modified or written to; we only read its settings.

• DF:GetFrameName(unit) (Frames/Core.lua) — new display entry point used by our four render call sites (Bars, Update ×2, Text Designer DataSource). DF:GetUnitName stays untouched as the public hook point for external addons.
• NK:GetDisplayName(unit) — honours a stored framePrecedence choice: DF's own nicknames resolve first by default; if the user chose NSRT, we yield by calling NSAPI:GetName(name, "DandersFrames") directly (their own internal call — honours their per-addon toggle and Secret Values guards).
• One-time popup — if both addons are set to manage names and no choice has been made, a DF-styled prompt asks which addon should decide, once. Deferred out of combat (PLAYER_REGEN_ENABLED), Esc re-asks next login. Only shown to users who actually HAVE DF nicknames (entries, received, or a broadcast nick), so plain NSRT users are never nagged.
• Settings control — General → Nicknames gains a Name precedence dropdown (only rendered when NSRT is installed) to change the choice later.
• All strings localised (L[...] + enUS registration; addon names passed as format args).

Notes

• When DF has precedence, NSRT still overwrites GetUnitName and runs its frame updates in the background — harmless (our render path resolves first), just a few wasted cycles on their side.
• Mid-session changes to NSRT's toggles are picked up by the precedence logic immediately, but the popup itself is only evaluated at login.
• Works with both load orders (NSRT inits nicknames at ADDON_LOADED, our hook installs at PLAYER_LOGIN).

Testing

• Both addons managing names → popup appears once; both buttons flip the displayed names live; choice persists across reloads (account-wide).
• Precedence verified in-game both ways via /dump probes on GetFrameName/GetDisplayName.
• Dropdown mirrors and updates the same stored choice.
• No NSRT installed → no popup, no dropdown, zero behaviour change.