feat: publish Dever core with project scaffolding and versioned AI skills

crates/dever-core/src/diagnostic.rs

@@ -0,0 +1,69 @@
+use std::fmt::Write;
+
+use crate::source::{SourceMap, Span};
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct Label {
+    pub span: Span,
+    pub message: String,
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct Diagnostic {
+    pub code: &'static str,
+    pub message: String,
+    pub primary: Span,
+    pub related: Vec<Label>,
+}
+
+impl Diagnostic {
+    pub(crate) fn error(code: &'static str, message: impl Into<String>, primary: Span) -> Self {
+        Self {
+            code,
+            message: message.into(),
+            primary,
+            related: Vec::new(),
+        }
+    }
+
+    pub fn render(&self, sources: &SourceMap) -> String {
+        let mut rendered = String::new();
+        render_label(
+            &mut rendered,
+            sources,
+            self.primary,
+            &format!(
+                "{}[{}]: {}",
+                if self.code.starts_with('W') {
+                    "warning"
+                } else {
+                    "error"
+                },
+                self.code,
+                self.message
+            ),
+        );
+        for related in &self.related {
+            render_label(
+                &mut rendered,
+                sources,
+                related.span,
+                &format!("note: {}", related.message),
+            );
+        }
+        rendered
+    }
+}
+
+fn render_label(output: &mut String, sources: &SourceMap, span: Span, message: &str) {
+    let source = sources.get(span.source);
+    let (line, column) = source.position(span.start);
+    let line_text = source.line(line);
+    writeln!(
+        output,
+        "{}:{line}:{column}: {message}",
+        source.path().display()
+    )
+    .expect("string formatting");
+    writeln!(output, "  | {line_text}").expect("string formatting");
+}