Preflight check

A file that was renamed the night before your talk, a patch that no longer matches its snapshot, or a scene id with a typo breaks the move that uses it, and you only find out on stage. The preflight check goes through all the acts of your play and checks every move, without running a single one.

In the act editor

The act editor always checks the act you’re editing, also when you didn’t run the preflight check, and checks again while you edit and when files in your workspace change:

• The header shows the number of errors and warnings. Click it to list them, with links to their scene and move.
• The scene list and move list show an error or warning icon with the number of problems. Hover the icon to read them.
• The move editor shows each problem below the field it’s about, like the Path of an open move. Problems that aren’t about a field are shown above the fields.
• The scene editor shows problems of the scene itself, like a missing notes file.
• A problem about a file that doesn’t exist has a Create file action, which creates the file (and its folders) and opens it.

Running the preflight check

To check the whole play and list all the problems in the Problems panel, run the preflight check:

• Command: Demo Time: Run preflight check
• Demo Time panel: More actions (...) > Run preflight check

The check reports what it finds in the Problems panel. Errors are problems that stop the move from working; warnings are problems that might. A notification shows how many moves were checked and how many problems were found.

After the first run, the check runs again when you save, create, delete or rename a file, so fixed problems disappear from the Problems panel.

Going to the move

Each problem shows its scene and move, like Scene 3 · Move 2. Click this link in the Problems panel to open the act file in the act editor with that move selected.

Clicking the problem itself opens the act file, but the act editor can’t show the line of the problem. For a file that doesn’t exist, the quick fix Create “path” creates the file and opens it. When you turned the act editor off with the demoTime.openInConfigEditor setting, the act file opens in the text editor at the move.

What gets checked

Files

Property	Moves	Check
path	open, markdownPreview, imagePreview, openSlide, copy, move, rename, deleteFile, applyPatch, insert, highlight, selection, replace, delete, positionCursor, write and executeScript	The file exists.
contentPath	create, insert, replace, write, applyPatch, copyToClipboard and snippet	The file exists and is in the workspace folder.
patch	applyPatch	The file exists and is in the workspace folder.
dest	copy, move and rename	Without overwrite: true, a warning when the destination already exists, as the move fails.
notes.path	Scenes	The notes file exists and is in the workspace folder.

Moves

• Patches apply: the applyPatch move applies its patch to the snapshot in contentPath, not to the file in the workspace, so the check can apply the patch to the snapshot and report a patch that doesn’t match it.
• Required properties: a move without a property it needs to run, like a copy move without dest, a highlight move without position or startPlaceholder, or an executeScript move without id or command. Moves with an unknown action, like a typo, are reported as well.
• Scene ids: a runDemoById move for a scene id that doesn’t exist in any act.
• Slide numbers: an openSlide move with a slide number higher than the number of slides in the file. Hidden slides count as well.
• State and script variables: a {STATE_key} or {SCRIPT_id} variable without an earlier setState move for that key or executeScript move with that id. The text of the variable stays in the move, so this is a warning.

Snippets

The moves of a snippet are checked with the args of the snippet move filled in, and their problems are reported at the snippet move. A placeholder that the args don’t set stays as text in the snippet:

• For a snippet with fields, a missing required field is an error, and a missing optional field that the snippet uses is a warning.
• For a snippet without fields, every {PLACEHOLDER} that the args or your variables don’t set is a warning.

How the check follows your play

The check goes through the acts in play order, and through the scenes and moves in each act in order:

• A file that an earlier create, copy, move or rename move creates isn’t reported as missing.
• A file that an earlier deleteFile, move or rename move removes is reported as missing.
• After an executeTerminalCommand, executeScript, executeVSCodeCommand or Copilot edit or agent move, a missing file is a warning instead of an error, as that move might create it.
• Disabled scenes and moves are skipped.
• Variables from .demo/variables.json are filled in. Paths with a variable that only gets its value while the play runs, like {DT_INPUT}, {DT_CLIPBOARD}, {STATE_...} or {SCRIPT_...}, are skipped.

Note

The check doesn’t verify positions or placeholders of moves like highlight and replace. Earlier moves often add the code these moves use, so their position can only be checked while the play runs.

Tip

The preflight check only checks that the slide file of an openSlide move exists and has the slide. Problems inside slide files, like a missing image or customTheme file, are reported in the Problems panel by the slide diagnostics. See problems in slide files.