fix(app): preserve provisional syntax at cached reveal boundaries

packages/app/src/components/markdown-prose/prepare.test.ts

@@ -77,6 +77,16 @@ describe("source-preserving prose", () => {
       expect(prepare(blocks, true, length)).toBe(prepareProse(blocks, noFiles, true, length));
     }
   });
+  it.each([
+    ["A ||literal|| and escaped \\* text.", 2, "A "],
+    ["Use `README.md` and example.com. Later.", 4, "Use "],
+    ["[unresolved label] later.", 12, "unresolved "],
+    ["[unresolved label] later.", 19, "unresolved label "],
+  ] as const)("keeps cached reveal boundaries literal: %s", (source, length, expected) => {
+    const prepare = createProsePreparer((text) => text === "README.md");
+    prepare([source], true, source.length);
+    expect(prepare([source], true, length)).toBe(expected);
+  });
   it("changes only prose pipes", () => {
     expect(prepareProse(["Keep ||literal|| and `a || b` and [a|b](https://x/a|b)."], noFiles)).toBe(
       "Keep \\|\\|literal\\|\\| and `a || b` and [a\\|b](https://x/a|b).",

packages/app/src/components/markdown-prose/prepare.ts

@@ -368,25 +368,37 @@ function compileBlock(
       edits.push({ ...edit, start: positions[edit.start]!, end: positions[edit.end]! });
   }
   const rendered = applyEdits(text, edits);
+  return { text: rendered, cuts, offsets: preparedOffsets(cuts, edits) };
+}
+function preparedOffsets(cuts: number[], edits: Edit[]): number[] {
   const offsets: number[] = [];
   let editIndex = 0;
   let delta = 0;
   for (const cut of cuts) {
-    while (editIndex < edits.length && edits[editIndex]!.end <= cut) {
+    while (
+      editIndex < edits.length &&
+      edits[editIndex]!.end <= cut &&
+      edits[editIndex]!.start < cut
+    ) {
       const edit = edits[editIndex++]!;
       delta += edit.text.length - (edit.end - edit.start);
     }
     offsets.push(cut + delta);
   }
-  return { text: rendered, cuts, offsets };
+  return offsets;
 }
 function paragraphCuts(source: string, trace: InlineTrace): number[] {
   const cuts: number[] = [];
   let depth = 0;
+  // A bracket can remain a provisional reference/link even after its closing bracket.
+  // Keep that suffix together until the block settles.
+  const bracket = source.indexOf("[");
+  const stableEnd = bracket < 0 ? source.length : bracket;
   for (const span of trace.spans) {
     if (span.insideLink) continue;
     if (depth === 0 && span.tokens.length === 0 && source[span.start] !== "&") {
-      for (let i = span.start; i < span.end; i++) if (source[i] === " ") cuts.push(i + 1);
+      for (let i = span.start; i < span.end; i++)
+        if (i < stableEnd && source[i] === " ") cuts.push(i + 1);
     }
     for (const token of span.tokens) depth += token.nesting;
   }