fix(shared): preserve paragraph breaks in the Bot system prompt

shared/bot-prompt.test.ts

@@ -0,0 +1,25 @@
+import { describe, expect, test } from "bun:test";
+import { SYSTEM_PROMPT } from "./bot-prompt";
+
+describe("SYSTEM_PROMPT", () => {
+  test("keeps paragraph breaks as blank lines instead of collapsing them into spaces", () => {
+    expect(SYSTEM_PROMPT).toContain("\n\n");
+    expect(SYSTEM_PROMPT).not.toContain("  ");
+  });
+
+  test("keeps each paragraph as one unbroken line of prose", () => {
+    for (const paragraph of SYSTEM_PROMPT.split("\n\n")) {
+      expect(paragraph).not.toContain("\n");
+      expect(paragraph.length).toBeGreaterThan(0);
+    }
+  });
+
+  test("still contains the full instruction text, unchanged in wording", () => {
+    expect(SYSTEM_PROMPT).toContain(
+      "You are a Bot with your own computer, a real web browser the person can watch you use.",
+    );
+    expect(SYSTEM_PROMPT).toContain(
+      "Say what you found or did in plain language, briefly.",
+    );
+  });
+});

shared/bot-prompt.ts

@@ -10,7 +10,7 @@
  * The prompt requires snapshot-first computer use. Element refs are opaque and valid only with the
  * snapshotId that produced them, so the Bot must read refs from the page before acting.
  */
-export const SYSTEM_PROMPT = [
+const SYSTEM_PROMPT_LINES = [
   "You are a Bot with your own computer, a real web browser the person can watch you use.",
   "When you are asked to look at, open, visit, check or read a web page, call computer_navigate.",
   "Never claim you cannot browse: opening a page is something you can actually do.",
@@ -53,4 +53,22 @@ export const SYSTEM_PROMPT = [
   "something to retry: say plainly what was blocked and why, and stop. Do not try another route to",
   "the same thing.",
   "Say what you found or did in plain language, briefly.",
-].join(" ");
+];
+
+/**
+ * `SYSTEM_PROMPT_LINES` uses `""` as a paragraph break. Joining the whole array with `" "` would
+ * collapse those breaks into a double space instead of a real paragraph gap, turning the prompt into
+ * one run-on block. Join each paragraph's lines with a space, then join paragraphs with a blank line.
+ */
+export const SYSTEM_PROMPT = SYSTEM_PROMPT_LINES.reduce<string[]>(
+  (paragraphs, line) => {
+    if (line === "") {
+      paragraphs.push("");
+      return paragraphs;
+    }
+    const last = paragraphs.length - 1;
+    paragraphs[last] = paragraphs[last] ? `${paragraphs[last]} ${line}` : line;
+    return paragraphs;
+  },
+  [""],
+).join("\n\n");