Preview and Compile

The graph can change before the file does. That gap is where you inspect the draft, undo an experiment, or decide the source edit is ready.

The problem

Saving every drag or field change immediately would make exploration risky. It would also hide the important boundary between graph configuration and C# behavior.

When to reach for it

Use the preview state whenever a graph, declaration, default, guard, signature, or member edit is pending. The banner says Previewing your changes. and the toolbar’s Compile becomes active.

Compile lives in the top toolbar only. The Previewing your changes. panel pinned to the top of the right rail counts the pending edits and offers Undo. Guard, property access, and overload default edits are written by the same Compile. The toolbar tooltip reads compile and save when work is pending, nothing to save when the graph matches source, and compiling… while the write is running. A pending change that still needs attention, such as a guard that is not ready, turns Compile off with Fix the pending change that needs attention before compiling.

See it

Figure 1. The canvas marks a pending draft before source is changed.

Do it

1. Make one supported graph or declaration change.
2. Look for Previewing your changes.. Inspect the changed node, wire, rail field, or source-shaped summary.
3. Use Undo before Compile to reverse the draft. Redo restores it while the source baseline is still current.
4. If the draft is correct, press Compile in the toolbar. Cmd/Ctrl+S runs the same pending-change flush.
5. Round Trip plans the smallest safe source mutation. It rechecks the file timestamp before writing.
6. The updated file is written atomically, imported by Unity, indexed, and parsed again.
7. Wait for the graph to return to its source-backed state. The preview banner clears when no pending work remains.
8. If Compile refuses, read the named reason. The file stays unchanged and the draft stays available for repair or discard.

You should see

A successful Compile produces ordinary C# and then reloads the graph from that C#. A refused Compile produces no partial write.

Change one thing

Move one node, change one literal, and rename the method as separate drafts. Notice that only the literal and rename affect C#; placement remains graph configuration. Undo the rename, then Compile the literal.

What it writes

Source-backed edits enter the .cs file. Layout, viewport, zoom, reroute knots, graph notes, and collapsed sections enter graph configuration instead. Round Trip does not insert canvas coordinates into C#.

C#

What it writes

C#

var coinValue = 2;

A source write is followed by a re-parse, so the graph returns to the C# Unity will compile.

When it goes wrong

When it goes wrong

Symptom	Check	Fix
Compile says nothing to save	Look for the preview banner and any changed rail state.	Make a source-backed draft; layout-only changes save as graph configuration.
Compile remains busy	Check whether Unity is compiling or importing.	Wait for Unity to become ready; the graph retries after editor work settles.
A refusal appears	Read the exact construct or declaration named in the message.	Repair the draft, discard it, or make that edit in C#.

Next

• What gets written
• When Compile refuses
• Canvas shortcuts