feat(FN-3871): add tracking issue title/body formatters

Added GitHub tracking issue title and body formatters to the dashboard (`packages/dashboard/src/github-tracking.ts`), with corresponding tests and documentation in the architecture docs. A changeset was included for this user-facing feature.

Fusion-Task-Id: FN-3871

packages/dashboard/src/__tests__/github-tracking.test.ts

@@ -1,6 +1,10 @@
 import { describe, expect, it, vi } from "vitest";
 import type { Task } from "@fusion/core";
-import { maybeCreateTrackingIssue } from "../github-tracking.js";
+import {
+  formatTrackingIssueBody,
+  formatTrackingIssueTitle,
+  maybeCreateTrackingIssue,
+} from "../github-tracking.js";
 
 function buildTask(overrides: Partial<Task> = {}): Task {
   return {
@@ -17,6 +21,82 @@ function buildTask(overrides: Partial<Task> = {}): Task {
   } as Task;
 }
 
+describe("formatTrackingIssueTitle", () => {
+  it("formats a normal title", () => {
+    expect(formatTrackingIssueTitle({ id: "FN-1", title: "Hello" })).toBe("[FN-1] Hello");
+  });
+
+  it("falls back for blank title", () => {
+    expect(formatTrackingIssueTitle({ id: "FN-1", title: "   \n\t " })).toBe("[FN-1] Untitled task");
+  });
+
+  it("collapses multiline whitespace", () => {
+    expect(formatTrackingIssueTitle({ id: "FN-1", title: "Hello\n\tWorld" })).toBe("[FN-1] Hello World");
+  });
+
+  it("truncates very long titles while preserving id prefix", () => {
+    const longTitle = "x".repeat(400);
+    const formatted = formatTrackingIssueTitle({ id: "FN-123", title: longTitle });
+    expect(formatted.startsWith("[FN-123] ")).toBe(true);
+    expect(formatted.length).toBeLessThanOrEqual(240);
+    expect(formatted.endsWith("…")).toBe(true);
+  });
+});
+
+describe("formatTrackingIssueBody", () => {
+  it("prefers first description paragraph", () => {
+    expect(formatTrackingIssueBody({
+      id: "FN-X",
+      description: "Primary paragraph\n\nSecond paragraph",
+      prompt: "Prompt paragraph",
+      summary: "Summary paragraph",
+    })).toBe("Fusion task: FN-X\n\nPrimary paragraph");
+  });
+
+  it("uses prompt when description is empty", () => {
+    expect(formatTrackingIssueBody({ id: "FN-X", description: "", prompt: "Prompt paragraph", summary: "Summary" }))
+      .toBe("Fusion task: FN-X\n\nPrompt paragraph");
+  });
+
+  it("uses summary when description and prompt are unavailable", () => {
+    expect(formatTrackingIssueBody({ id: "FN-X", summary: "Summary paragraph" }))
+      .toBe("Fusion task: FN-X\n\nSummary paragraph");
+  });
+
+  it("falls back when prompt is undefined and sources are empty", () => {
+    expect(formatTrackingIssueBody({ id: "FN-X", description: "  ", summary: "   " }))
+      .toBe("Fusion task: FN-X\n\nNo summary available.");
+  });
+
+  it("strips markdown noise including headings, bullets, and code fences", () => {
+    const body = formatTrackingIssueBody({
+      id: "FN-X",
+      description: "# Heading\n- bullet\n1. numbered\n```ts\nconst x = 1;\n```\nfinal",
+    });
+    expect(body).toBe("Fusion task: FN-X\n\nHeading bullet numbered const x = 1; final");
+  });
+
+  it("truncates summary to 500 characters with ellipsis", () => {
+    const body = formatTrackingIssueBody({ id: "FN-X", description: "a".repeat(600) });
+    const summary = body.replace("Fusion task: FN-X\n\n", "");
+    expect(summary.length).toBe(500);
+    expect(summary.endsWith("…")).toBe(true);
+  });
+
+  it("removes fusion-style localhost task urls", () => {
+    const body = formatTrackingIssueBody({
+      id: "FN-1",
+      description: "See http://localhost:4040/tasks/FN-1 and continue",
+    });
+    expect(body).not.toContain("localhost");
+    expect(body).not.toMatch(/https?:\/\/[^\s]*\/tasks\/FN-/);
+  });
+
+  it("always starts with fusion task reference", () => {
+    expect(formatTrackingIssueBody({ id: "FN-99", description: "hello" }).startsWith("Fusion task: FN-99\n\n")).toBe(true);
+  });
+});
+
 describe("maybeCreateTrackingIssue", () => {
   it("returns tracking_disabled when not enabled", async () => {
     const result = await maybeCreateTrackingIssue(buildTask({ githubTracking: { enabled: false } }), {
@@ -89,7 +169,7 @@ describe("maybeCreateTrackingIssue", () => {
     const linkGithubIssue = vi.fn();
     const recordActivity = vi.fn();
 
-    const result = await maybeCreateTrackingIssue(buildTask({ title: "Test", githubTracking: { enabled: true } }), {
+    const result = await maybeCreateTrackingIssue(buildTask({ title: "Test", description: "Short body", githubTracking: { enabled: true } }), {
       taskStore: { linkGithubIssue, recordActivity } as any,
       githubClient: { createIssue } as any,
       projectSettings: {},
@@ -99,6 +179,12 @@ describe("maybeCreateTrackingIssue", () => {
 
     expect(result.created).toBe(true);
     expect(createIssue).toHaveBeenCalledTimes(1);
+    expect(createIssue).toHaveBeenCalledWith(expect.objectContaining({
+      title: "[FN-1] Test",
+      body: expect.stringMatching(/^Fusion task: FN-1\n\n/),
+    }));
+    const calledBody = createIssue.mock.calls[0][0]?.body as string;
+    expect(calledBody.length).toBeLessThanOrEqual("Fusion task: FN-1\n\n".length + 500);
     expect(linkGithubIssue).toHaveBeenCalledWith("FN-1", expect.objectContaining({ owner: "o", repo: "r", number: 12 }));
     expect(recordActivity).toHaveBeenCalledWith(expect.objectContaining({
       metadata: expect.objectContaining({ type: "github-issue-created", repo: "o/r", number: 12 }),