What survives a re-dress
A dress is derived data, and a re-dress deletes what it is about to replace. The engine tracks which objects it rebuilt, replaces their dressed twins, and leaves the rest alone. Hand work that has to last belongs in your own collection, outside iCity’s.
The rule
The dress is derived data. Every object the dress created carries one of iCity's own stamps, and a dress removes the stamped objects it is about to replace before it imports the new ones. Anything carrying a stamp is replaceable; anything else is yours.
Which objects go depends on how much of the city is being re-dressed. A partial re-dress removes only the front end of the objects it sends; a full dress removes every stamped object in the file. Either way, the decision is made by the stamp, not by where the object sits in the Outliner.
Your city is not your .blend. The draft lives in a separate engine process, started from Draft, and is saved by the header S button into Documents/iCity 2/<project>. See How iCity fits with Blender.
What a re-dress reaches
Each city object the engine builds gets one dressed twin, named for it with an _FE tail. The addon keeps a counter on the object and stamps the twin with the counter's value at the moment it was baked. When the engine rebuilds an object the counter moves and the twin is stale, so that object goes up on the next sync. An object the engine did not rebuild keeps its counter, keeps its twin, and is not sent.
The Outliner in a dressed project, expanded so one city object and its matching _FE twin are both visible on screen, with the iCity 2 and iCity2 Front End collections both showing.
When it is sent, its old front end is deleted at that moment rather than when the result comes back — the patch you edited goes bare for the round trip. Deleted with the twin is everything the dress derived from it: the prop clouds, the extracted paths, the scattering carriers. That is why deleting a road in Draft takes its props and markings with it.
- —A partial re-dress — City sync after a draft change — clears only the twins it sent.
- —A full dress — a theme job, or the Theme tab's Start with default theme — clears every object in the file carrying a front-end or linker stamp, then imports the new dress.
- —Assets appended from the library are the one exception. They are shared across the city and are never deleted by either clear.
What you did, and what happens next dress
Keep hand work in your own collection
This is the habit worth forming. Work that has to last should be your own object, in your own collection, outside the iCity 2 collection tree. Nothing there is stamped, so no dress reaches it, and nothing there is uploaded as city input.
The Outliner of a dressed .blend showing the iCity 2 collection tree collapsed and, as a sibling at the same level of the Scene Collection, a user-made collection holding a hand-modelled object. Both must be enabled, not switched off.
If what you want to keep started life as dressed geometry, copying it is not enough on its own. Blender copies an object's custom properties with it, and iCity's stamps are custom properties. After you duplicate, open Object Properties → Custom Properties on the copy and delete the entries whose names begin with icity2_, and rename it so it no longer ends in _FE. Then it is an ordinary Blender object.
Object Properties → Custom Properties expanded on a Shift+D duplicate of a dressed object, with every entry whose name begins with icity2_ readable, and the object's name ending in _FE.001 visible in the same frame.
A plain Shift+D duplicate of a dressed object is deleted along with the original. The sweep matches every object whose name resolves to the doomed one, and Blender's .001 suffix is discounted before the comparison.
Do not switch a collection off in the Outliner to keep it out of the way. An object in a disabled collection is not in the view layer and cannot be exported, and the send stops with “Switch the collection back on in the Outliner and send again” rather than charging you for a city with holes in it.
Locking, and the UNSYNCED warning
There is one way to hold a city object out of the engine's reach. A locked object is frozen out of procedural editing: the engine's re-emits skip it and leave its mesh alone, the gizmos ignore it, its role material swaps to a darker locked shade, and it becomes normally selectable and editable with Blender's own tools. The selection header shows UNSYNCED while an object is in that state.
A locked city object selected, captured so two things are in one frame: the selection header reading UNSYNCED, and the object itself in the viewport wearing the darker locked role material beside an unlocked neighbour in the normal shade.
The Lock button was removed from the panel, so locking is not something you can reach from the interface today. The operator is still registered: press F3 in Blender and search for Lock / Unlock. It acts on the selection, and if anything selected is unlocked it locks everything selected.
Blender's F3 search open over the iCity 2 workspace with “lock” typed, showing the Lock / Unlock entry in the result list. A city object must be selected behind it.
To go back, search F3 for Sync. It unlocks the selected objects and regenerates the city so the procedural system reclaims their geometry — which means the hand edits you locked to protect are regenerated over. That is what re-syncing is.
Locking guards the object against the engine rebuilding it. It is not a guard against a dress: the dress replaces twins, and the twin is a separate object.
Undo, and getting the result out
You cannot undo a dress. The linker suspends Blender's global undo while it works — a dressed file is large enough that snapshotting it for each of the dozens of imports cost minutes of freeze — so the dress is not a step on the undo stack. Your own Ctrl+Z keeps working for everything you do. To take a dress back, re-dress.
There is no export operator in the addon — the Export tab is commented out of the rail. The dressed geometry is appended into your .blend as real data, not linked, so Blender's own File → Export sees it like any other object. See What is in your .blend after a dress for where it lands and what to select.
If you want a dressed city that stops changing under you, put City sync on Manual so a draft edit no longer re-dresses by itself. That is the ▾ beside the header sync button; Re-dressing after a change covers it.
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