diff --git a/.github/fetch-source-trigger-2.txt b/.github/fetch-source-trigger-2.txt
new file mode 100644
index 0000000..dd7d980
--- /dev/null
+++ b/.github/fetch-source-trigger-2.txt
@@ -0,0 +1 @@
+Temporary source-fetch trigger for the private CTF analysis.
diff --git a/.github/workflows/fetch-firefox-asan.yml b/.github/workflows/fetch-firefox-asan.yml
index 285457c..d395f55 100644
--- a/.github/workflows/fetch-firefox-asan.yml
+++ b/.github/workflows/fetch-firefox-asan.yml
@@ -1,10 +1,9 @@
-name: Fetch Firefox ASan artifact
+name: Fetch sparse Firefox GC source
 
 on:
   push:
     paths:
       - '.github/workflows/fetch-firefox-asan.yml'
-  pull_request:
   workflow_dispatch:
 
 permissions:
@@ -13,22 +12,46 @@ permissions:
 jobs:
   fetch:
     runs-on: ubuntu-latest
-    timeout-minutes: 30
+    timeout-minutes: 20
     steps:
-      - name: Download official Mozilla linux64 ASan optimized build
+      - name: Checkout the exact affected Firefox revision sparsely
+        uses: actions/checkout@v4
+        with:
+          repository: dev-dharan24/firefox
+          ref: 2c934dbbd7bdb99f4e4edd7fb22aa06c29192ec6
+          path: firefox
+          filter: blob:none
+          sparse-checkout-cone-mode: false
+          sparse-checkout: |
+            js/src/gc/**
+            js/src/jit-test/tests/gc/**
+            js/src/jit-test/tests/weakmap/**
+            js/src/tests/non262/WeakMap/**
+            js/src/tests/non262/gc/**
+            js/public/**
+            mfbt/**
+            modules/libpref/**
+            dom/base/**
+            xpcom/base/**
+
+      - name: Package the checked-out source
         shell: bash
         run: |
           set -euxo pipefail
-          URL='https://firefox-ci-tc.services.mozilla.com/api/index/v1/task/gecko.v2.mozilla-central.latest.firefox.linux64-asan-opt/artifacts/public/build/target.tar.xz'
-          curl --fail --location --retry 5 --retry-all-errors --output firefox-asan-target.tar.xz "$URL"
-          sha256sum firefox-asan-target.tar.xz | tee SHA256SUMS
-          ls -lh firefox-asan-target.tar.xz SHA256SUMS
-      - name: Upload browser archive
+          git -C firefox rev-parse HEAD | tee SOURCE_REVISION
+          git -C firefox show -s --format=fuller HEAD | tee SOURCE_COMMIT.txt
+          tar --exclude='firefox/.git' -cJf firefox-gc-source-2c934db.tar.xz firefox SOURCE_REVISION SOURCE_COMMIT.txt
+          sha256sum firefox-gc-source-2c934db.tar.xz | tee SHA256SUMS
+          ls -lh firefox-gc-source-2c934db.tar.xz SOURCE_REVISION SOURCE_COMMIT.txt SHA256SUMS
+
+      - name: Upload sparse source archive
         uses: actions/upload-artifact@v4
         with:
-          name: firefox-linux64-asan-opt
+          name: firefox-gc-source-2c934db
           path: |
-            firefox-asan-target.tar.xz
+            firefox-gc-source-2c934db.tar.xz
+            SOURCE_REVISION
+            SOURCE_COMMIT.txt
             SHA256SUMS
           compression-level: 0
           retention-days: 1
diff --git a/tmp-firefox-asan-trigger.txt b/tmp-firefox-asan-trigger.txt
new file mode 100644
index 0000000..149020c
--- /dev/null
+++ b/tmp-firefox-asan-trigger.txt
@@ -0,0 +1 @@
+Trigger the temporary pull-request workflow that fetches the official Mozilla linux64 ASan optimized browser artifact.