Cell Highlighter

A VS Code extension for cell visualization and code sectioning, with Julia-specific CodeLens and execution integration.

[!NOTE] As of version 1.0.0, this extension has been renamed from Julia Cell Highlighter to Cell Highlighter and requires VS Code 1.92.0 or later.

Existing juliaCellHighlighter.* settings are migrated automatically to cellHighlighter.* when the extension activates. Explicit values are moved at their original VS Code configuration scope, including language-specific overrides, and the old values are removed after migration.

The default focusCell.excludePatterns list is now empty. To restore the previous default exclusions for src, test, deps, and docs, add this line to settings.json:

"cellHighlighter.focusCell.excludePatterns": ["**/src/**", "**/test/**", "**/deps/**", "**/docs/**"]

Cell

The visual system has two independent cell layers:

• focusCell: follows the cursor and highlights the currently focused cell. Julia CodeLens and Run Cell use this layer's delimiters.
• guideCell: stays visible independently of the cursor. By default it draws only a top border, which replaces the former separator-line feature.

Each layer can use its own delimiter regexes, or follow the other layer's effective delimiters. By default, guideCell follows focusCell:

"cellHighlighter.focusCell.delimiters": ["^##(?!#)", "^#%%", "^#\\s+%%"],
"cellHighlighter.guideCell.delimiters": "followFocusCell"

The relationship can be reversed when the guide layer is the delimiter source:

"cellHighlighter.focusCell.delimiters": "followGuideCell",
"cellHighlighter.guideCell.delimiters": ["^##(?!#)"]

Or the two layers can remain fully independent, for example executable Julia cells using #%% while ## is only a persistent visual chapter boundary:

"cellHighlighter.focusCell.delimiters": ["^#%%"],
"cellHighlighter.guideCell.delimiters": ["^##(?!#)"]

Only one layer may follow the other. Configuring focusCell.delimiters as "followGuideCell" and guideCell.delimiters as "followFocusCell" at the same time is invalid and temporarily falls back to the built-in delimiter regexes until the cycle is fixed. The layers may overlap; when both style the same boundary, focusCell has visual priority while non-conflicting guide borders remain visible.

Language Scope

Both visual layers are language-independent internally. The focus layer remains Julia-only by default for backward compatibility, and the guide layer follows it:

"cellHighlighter.focusCell.languages": ["julia"],
"cellHighlighter.guideCell.languages": "followFocusCell"

Either layer may follow the other, but they cannot follow each other at the same time:

"cellHighlighter.focusCell.languages": "followGuideCell",
"cellHighlighter.guideCell.languages": ["julia", "latex"]

Use "*" to enable a layer for every language:

"cellHighlighter.focusCell.languages": ["*"],
"cellHighlighter.guideCell.languages": "followFocusCell"

Delimiter and visual settings are language-overridable, so VS Code language-specific settings can define different rules without plugin-specific language maps:

"cellHighlighter.focusCell.languages": ["*"],
"cellHighlighter.guideCell.languages": "followFocusCell",

"[julia]": {
  "cellHighlighter.focusCell.delimiters": ["^#%%"],
  "cellHighlighter.guideCell.delimiters": ["^##(?!#)"]
},

"[markdown]": {
  "cellHighlighter.focusCell.delimiters": ["^<!--\\s*%%.*-->\\s*$"],
  "cellHighlighter.guideCell.delimiters": ["^#{1,6}\\s+"]
}

CodeLens, Run Cell, Run Cell and Move, and Run Current File remain Julia-only integration features.

Julia Execution

Cell Highlighter provides CodeLens actions for individual cells and a separate command for running the entire active buffer.

Run Cell (CodeLens)

CodeLens actions can appear above non-empty focusCell delimiter lines:

• always (default): show Run Cell and Run Cell and Move for every executable cell
• current: show the actions only for the cell containing the cursor
• never: hide all Cell Highlighter CodeLens actions

Configure this behavior with cellHighlighter.codeLensMode.

The execution backend is controlled by cellHighlighter.juliaExecutionBackend:

• auto (default): use the Julia extension when its execution command is available; otherwise fall back to a persistent terminal Julia REPL
• julia: execute through the Julia extension
• terminal: execute through a persistent terminal Julia REPL, with one session per workspace folder or standalone-file directory

Cell boundaries always come from focusCell.delimiters, and the exact resulting range is sent to the selected backend. The Julia extension acts only as an execution transport and does not reinterpret the cell boundary. Empty cells receive no CodeLens actions and are never replaced by a neighboring cell.

Run Current File

Run the full active Julia buffer from either location:

• Command palette: Cell Highlighter: Run Current File
• Editor title: enable the optional ▷ button with cellHighlighter.showRunFileButton

Run Current File uses the terminal backend to execute the active buffer, including unsaved changes, while preserving the document path as Julia source context. It starts or reuses the appropriate integrated Julia REPL automatically.

Settings

Full key format: cellHighlighter.<setting>.

Exclusion patterns use glob syntax, including *, ?, **, character classes such as [0-9], and brace alternatives such as {src,test}.

Commands

• Toggle focus cell: Ctrl+Shift+H (Windows/Linux) / Cmd+Shift+H (macOS)
• Run Current File: command palette, or optional editor-title button

License

MIT