feat: source citations with footnotes in the transcript (#21)

src/lib/types.ts

@@ -84,12 +84,39 @@ export interface PendingAttachment extends Attachment {
   /** Base64 of the image, with no `data:` URL prefix. Ollama wants it bare. */
   base64: string;
 }
+/**
+ * One numbered source, as a web tool found it.
+ *
+ * The number is the whole point: it is assigned once per turn, printed to the
+ * model in the tool result, and rendered as the marker the reader clicks. The
+ * model and the reader therefore agree on what `[3]` means without either of them
+ * being asked to remember a URL.
+ */
+export interface Source {
+  /** The number the model cites. One-based, and never reused for a different page. */
+  index: number;
+  /** Page title, or the URL when the page had none. */
+  title: string;
+  url: string;
+}
+
 /** What a tool actually returned during a turn, kept for display and debugging. */
 export interface ToolCallRecord {
   name: string;
   arguments: Record<string, unknown>;
   result: string;
   isError: boolean;
+  /**
+   * The sources this call added to the turn, if it consulted any.
+   *
+   * Only what this call found, never the turn's running total: the whole list is
+   * the flattening of a turn's records, so storing the total here would write
+   * the same page once per later call.
+   *
+   * Absent on turns stored before sources were numbered, which is honest rather
+   * than empty: those answers never cited a number, so there is nothing to draw.
+   */
+  sources?: Source[];
   /**
    * Set when the call was refused because the turn had already made it twice.
    *