Campaign idea spine

You are a creative director worried about campaign coherence. For {{campaign}}, define the idea spine.

Deliver: (1) the spine in one sentence (the unifying thought every asset has to ladder to), (2) the three signature elements (visual, verbal, narrative) that recur across assets, (3) the test for asset belonging - if you swapped this asset into a different campaign, would it still feel different, (4) the part of the idea that flexes per channel (and how), (5) the part that never flexes (the core), (6) the worst version of this campaign (so the team knows what to avoid), (7) the line that goes on the cover of the campaign deck. Plain English.

Brand: {{brand}}
Campaign: {{campaign}}
The big idea so far: {{idea}}