feat: render LaTeX, custom HTML and diagrams in the transcript (#19)

src/__tests__/code.test.ts

@@ -1,7 +1,10 @@
 import { describe, expect, it } from "vitest";
 import {
+  fenceAsciiArt,
   inferLanguage,
   labelCodeFences,
+  mapOutsideCodeSpans,
+  normalizeFenceLabels,
   promoteStandaloneCodeSpans,
   repairCodeBlocks,
   restoreUrlLinks,
@@ -416,3 +419,60 @@ describe("labelCodeFences", () => {
     expect(labelCodeFences("  ```\n  ls\n  ```")).toContain("  ```bash");
   });
 });
+
+describe("mapOutsideCodeSpans", () => {
+  it("applies the transform everywhere a span is not", () => {
+    expect(mapOutsideCodeSpans("a `b` c", (text) => text.toUpperCase())).toBe("A `b` C");
+  });
+
+  it("matches a delimiter of the same length only", () => {
+    // A single-backtick span inside a double-backtick span is content, not a
+    // closer, so the inner one is left exactly as written.
+    expect(mapOutsideCodeSpans("`` `a` ``", (text) => text.toUpperCase())).toBe("`` `a` ``");
+  });
+
+  it("treats an unclosed run as text and carries on after it", () => {
+    expect(mapOutsideCodeSpans("a ` b", (text) => text.toUpperCase())).toBe("A ` B");
+  });
+});
+
+describe("normalizeFenceLabels", () => {
+  it("names a language that resolves in place of one that does not", () => {
+    expect(normalizeFenceLabels("```console\nls\n```")).toBe("```bash\nls\n```");
+  });
+
+  it("drops a label that carries no information", () => {
+    expect(normalizeFenceLabels("```text\nplain\n```")).toBe("```\nplain\n```");
+  });
+
+  it("leaves a language the model chose alone", () => {
+    const input = "```rust\nfn main() {}\n```";
+    expect(normalizeFenceLabels(input)).toBe(input);
+  });
+});
+
+describe("fenceAsciiArt", () => {
+  it("fences a tree so its columns stay monospaced", () => {
+    expect(fenceAsciiArt("src/\n├── a.ts\n└── b.ts")).toBe("```\nsrc/\n├── a.ts\n└── b.ts\n```");
+  });
+
+  it("fences an ASCII table drawn with borders", () => {
+    const art = "+---+---+\n| a | b |\n+---+---+";
+    expect(fenceAsciiArt(art)).toBe("```\n" + art + "\n```");
+  });
+
+  it("leaves a real GFM table to the table renderer", () => {
+    const table = "| a | b |\n| --- | --- |\n| 1 | 2 |";
+    expect(fenceAsciiArt(table)).toBe(table);
+  });
+
+  it("leaves prose that contains one pipe alone", () => {
+    const prose = "Here is what it does:\n| a | b |";
+    expect(fenceAsciiArt(prose)).toBe(prose);
+  });
+
+  it("leaves a diagram that is already fenced alone", () => {
+    const fenced = "```\n├── a.ts\n└── b.ts\n```";
+    expect(fenceAsciiArt(fenced)).toBe(fenced);
+  });
+});