Never inject a duplicate stats.js tag when one is already present

lib/github/install-audience.ts

@@ -19,7 +19,11 @@ import {
   openPullRequest,
   putFile,
 } from "./repos";
-import { findInstallCandidates, previewInstallAtPath } from "./install-tracker";
+import {
+  findInstallCandidates,
+  hasTrackerReference,
+  previewInstallAtPath,
+} from "./install-tracker";
 
 const SITE_ORIGIN = env.siteUrl.replace(/\/$/, "");
 const BRANCH_PREFIX = "crawlproof/audience-hub";
@@ -284,30 +288,48 @@ export async function installAudienceHub(
       repo: input.repo,
       rootPath: input.rootPath,
     });
+
+    // Pass 1: if ANY candidate file already references stats.js, the
+    // tracker is installed — even when it lives in a lower-ranked file or
+    // is formatted across multiple lines. Never add a duplicate tag.
+    const contents = new Map<string, { sha: string; content: string }>();
     for (const candidate of candidates) {
-      const preview = await previewInstallAtPath({
+      const file = await getFileContent({
         token: input.token,
         owner: input.owner,
         repo: input.repo,
         path: candidate.path,
-        projectId: input.projectId,
+        ref: base,
       });
-      if (preview.status === "already_installed") {
-        trackerAlready = preview.path;
+      if (!file) continue;
+      contents.set(file.path, { sha: file.sha, content: file.content });
+      if (hasTrackerReference(file.content)) {
+        trackerAlready = file.path;
         break;
       }
-      if (preview.status === "ready") {
-        const file = await getFileContent({
+    }
+
+    // Pass 2: only when no candidate has it do we inject into the best one.
+    if (!trackerAlready) {
+      for (const candidate of candidates) {
+        const preview = await previewInstallAtPath({
           token: input.token,
           owner: input.owner,
           repo: input.repo,
-          path: preview.path,
-          ref: base,
+          path: candidate.path,
+          projectId: input.projectId,
         });
-        if (file) {
-          trackerEdit = { path: file.path, sha: file.sha, after: preview.after };
+        if (preview.status === "already_installed") {
+          trackerAlready = preview.path;
+          break;
+        }
+        if (preview.status === "ready") {
+          const file = contents.get(preview.path);
+          if (file) {
+            trackerEdit = { path: preview.path, sha: file.sha, after: preview.after };
+          }
+          break;
         }
-        break;
       }
     }
   }

lib/github/install-tracker.ts

@@ -152,6 +152,17 @@ function injectBeforeBodyClose(
   return updated;
 }
 
+/**
+ * Loose duplicate guard: does this file reference our stats.js at all?
+ * The line-based regex below only matches single-line tags, so a
+ * prettier-formatted multi-line <Script ... /> slips past it and we'd
+ * inject a second copy. Any reference to the tracker origin's /stats.js
+ * means "already installed" for injection purposes.
+ */
+export function hasTrackerReference(content: string): boolean {
+  return content.includes(`${TRACKER_ORIGIN}/stats.js`);
+}
+
 function trackerTagLineRe() {
   const origin = escapeRegExp(TRACKER_ORIGIN);
   return new RegExp(
@@ -395,6 +406,11 @@ export async function previewInstallAtPath(input: {
   if (normalized) {
     return { status: "already_installed", path: file.path };
   }
+  // Multi-line or unusually formatted tags won't match the line regex but
+  // are still an install — never inject a duplicate next to one.
+  if (hasTrackerReference(file.content)) {
+    return { status: "already_installed", path: file.path };
+  }
   if (!/<\/body>/i.test(file.content)) {
     return {
       status: "not_a_template",
@@ -593,6 +609,11 @@ export async function installTracker(input: InstallInput): Promise<InstallResult
     if (normalized) {
       return { kind: "already", path: file.path };
     }
+    // Same guard as previewInstallAtPath: a multi-line tag the line regex
+    // can't parse still counts as installed.
+    if (hasTrackerReference(file.content)) {
+      return { kind: "already", path: file.path };
+    }
     if (/<\/body>/i.test(file.content)) {
       return { kind: "hit", file };
     }

tests/audience-hub.test.ts

@@ -7,6 +7,7 @@ import {
   generatedClientHelper,
   serverHelperPath,
 } from "@/lib/github/install-audience";
+import { hasTrackerReference } from "@/lib/github/install-tracker";
 
 describe("statusForEvent", () => {
   it("maps lifecycle events to lifecycle statuses", () => {
@@ -123,6 +124,36 @@ describe("generated files", () => {
   });
 });
 
+describe("hasTrackerReference (duplicate-install guard)", () => {
+  // env.siteUrl is stubbed to http://localhost:3000 in tests/setup.ts.
+  const origin = "http://localhost:3000";
+
+  it("detects a single-line script tag", () => {
+    expect(
+      hasTrackerReference(
+        `<body><script data-site="abc" src="${origin}/stats.js" async></script></body>`,
+      ),
+    ).toBe(true);
+  });
+
+  it("detects a prettier-formatted multi-line <Script /> tag", () => {
+    const layout = `        <Script
+          data-site="11111111-2222-3333-4444-555555555555"
+          src="${origin}/stats.js"
+          strategy="afterInteractive"
+        />
+      </body>`;
+    expect(hasTrackerReference(layout)).toBe(true);
+  });
+
+  it("ignores files without the tracker", () => {
+    expect(hasTrackerReference("<body><h1>hi</h1></body>")).toBe(false);
+    expect(
+      hasTrackerReference('<script src="https://other-analytics.example/stats.js">'),
+    ).toBe(false);
+  });
+});
+
 describe("project ingest keys", () => {
   it("mints cpk_ keys and verifies by peppered sha256", async () => {
     const { mintProjectKey, hashProjectKey, isProjectKeyShape } = await import(