cursor.md

Source selection and function arguments

Start here · Read this to choose an observation target precisely, inspect a function with custom arguments, or recover a lost selection.

Select an expression and inspect a function

{
  "operation": "apply",
  "input": {
    "cursor": {
      "file": "/model.ts",
      "regex": "return ([^;]+);",
      "lines": [20, 40],
      "arguments": "[10, 5, 6]"
    },
    "render": {
      "view": "front"
    },
    "topology": true,
    "type": true
  }
}

The complete regex match must be unique, with exactly one capturing group. The capture selects the expression; an empty capture places a caret. Use (?:...) for any other groups. An unmatched capture is invalid. Optional lines is an inclusive, 1-based range; both the whole match and capture must fall inside it, excluding the final line's newline. Regex anchors/lookarounds still see the full source; overlapping matches count toward uniqueness. Default flags are u; i, m, s, u, or v may be supplied in flags. Regex evaluation is bounded in a separate worker. Returned offsets are UTF-16 with Monaco line/column positions.

The cursor matches source after this apply's file changes. Omitting it retains your tracked agent cursor. If edits invalidate the selection, explicitly select again. After a page reload, reread file versions and supply a new cursor before observing. Agent decorations never take over the user's selection.

cursor.arguments is a TypeScript array-expression string evaluated in the containing module's scope; imports, variables, and model objects are available. Explicit arguments take priority over the function's JSDoc @code3d.arguments, then ordinary execution. Omission does not reuse previous custom arguments; "[]" explicitly calls with no arguments. This also works without JSDoc.

Related reading

See observation for output options, sketches for 2D targets, and files for changing source in the same request.