AST parse observations

std/ast exposes the installed parser through typed observations. It preserves the native parser-health receipt instead of guessing grammar reliability from the language name, error span, bracket balance, or number of declarations.

import { ast_parse_delta } from "std/ast"

fn main(harness: Harness) {
  const result = ast_parse_delta(harness.ast, {
    before: "fn example() {}\n",
    after: "fn example() { let value = ; }\n",
    language: "rust",
  })
  print(json_stringify(result))
}

Contracts#

ast_parse_errors(ast, source, language) observes one source string. ast_parse_errors_result(value, language) decodes an already obtained native observation. Coordinates are zero-based except the one-based display line. Malformed coordinates or contradictory support and health produce an explicit unavailable observation. Missing provenance never establishes a clean parse.

ast_parse_delta(ast, request) compares the source before and after an edit. Omit before for a new file. It parses each distinct source once, relocates findings in the unchanged suffix, and compares findings individually. Replacing one old defect with a different defect still produces a finding when the total error count stays equal.

finding_count reports every fresh finding. findings retains at most twenty; primary selects the smallest error span for located feedback. Before and after error counts are nullable: null means no attested measurement, whereas 0 means an observed zero. An unchanged error set does not establish clean source.

Parser findings alone cannot establish that source is invalid. An installed compiler or another named independent authority must resolve inconclusive coverage. Hosts retain approval, mutation, rollback, and presentation ownership.