diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index a546292a32ef..0d470f273e39 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -1141,13 +1141,16 @@ jobs:
   #   them. optional-e2e.yml reports the results in a PR comment.
   job_optional_e2e_tests:
     name: E2E Tests (optional)
-    # We only run E2E tests for non-fork PRs because the E2E tests require secrets to work and they can't be accessed from forks
+    # We only run E2E tests for non-fork PRs because the E2E tests require secrets to work and they can't be accessed from forks.
+    # Dependabot PRs are skipped by author, not by `github.actor`: once the Gitflow app pushes the deduped lockfile
+    # (dependabot-dedupe-push.yml), the actor is the app and the run would otherwise get the E2E secrets.
     # We need to add the `always()` check here because the previous step has this as well :(
     # See: https://github.com/actions/runner/issues/2205
     if:
       always() && needs.job_get_metadata.outputs.is_release != 'true' && needs.job_build_tarballs.result == 'success' &&
       needs.job_build.outputs.e2e-matrix-optional != '{"include":[]}' && (github.event_name != 'pull_request' ||
-      github.event.pull_request.head.repo.full_name == github.repository) && github.actor != 'dependabot[bot]'
+      github.event.pull_request.head.repo.full_name == github.repository) && github.event.pull_request.user.login !=
+      'dependabot[bot]'
     needs: [job_get_metadata, job_build, job_build_tarballs]
     # This job only waits for optional-e2e.yml, which can take most of an hour. GitHub runners are free for public
     # repos and Namespace runners are paid per minute, so the wait runs here and the tests run on Namespace.
diff --git a/.github/workflows/dependabot-dedupe-push.yml b/.github/workflows/dependabot-dedupe-push.yml
new file mode 100644
index 000000000000..3fce5447b7ba
--- /dev/null
+++ b/.github/workflows/dependabot-dedupe-push.yml
@@ -0,0 +1,134 @@
+name: 'Dependabot: Push deduped lockfile'
+
+# Pushes the lockfile from `dependabot-dedupe.yml` to the Dependabot PR branch.
+#
+# This workflow holds the Gitflow app token, so it never runs code from the PR. Everything it
+# receives is untrusted: anyone with write access can push to a Dependabot branch, and the run that
+# produced the artifact used the PR's version of `dependabot-dedupe.yml`. So it looks the PR up
+# through the API, accepts only a single regular `pnpm-lock.yaml` file and commits nothing else.
+#
+# The app token is limited to `contents: write` on this repository, not to `dependabot/**` branches, so
+# nothing from the PR may run before it is minted. Pushing as the app also changes `github.actor` on the
+# PR's next CI run, so jobs that keep secrets away from Dependabot must check the PR author, not the actor.
+
+on:
+  workflow_run:
+    workflows: ['Dependabot: Dedupe lockfile']
+    types: [completed]
+
+permissions:
+  actions: read
+  contents: read
+  pull-requests: read
+
+concurrency:
+  group: dependabot-dedupe-push-${{ github.event.workflow_run.head_sha }}
+  cancel-in-progress: false
+
+jobs:
+  push:
+    name: Push deduped lockfile
+    if: |
+      github.event.workflow_run.conclusion == 'success'
+      && github.event.workflow_run.event == 'pull_request'
+      && github.event.workflow_run.head_repository.full_name == github.repository
+    runs-on: namespace-profile-sentry-javascript-small
+    timeout-minutes: 5
+    env:
+      GH_TOKEN: ${{ github.token }}
+      RUN_ID: ${{ github.event.workflow_run.id }}
+      HEAD_SHA: ${{ github.event.workflow_run.head_sha }}
+    steps:
+      - name: Find artifact and Dependabot PR
+        id: pr
+        run: |
+          artifacts=$(gh api "repos/${GITHUB_REPOSITORY}/actions/runs/${RUN_ID}/artifacts" \
+            --jq '[.artifacts[] | select(.name == "pnpm-lock")] | length')
+          if [ "$artifacts" != "1" ]; then
+            echo "No deduped lockfile to push."
+            exit 0
+          fi
+
+          head_ref=$(gh api "repos/${GITHUB_REPOSITORY}/commits/${HEAD_SHA}/pulls" |
+            jq -r --arg repo "$GITHUB_REPOSITORY" --arg sha "$HEAD_SHA" '
+              [.[] | select(.state == "open"
+                and .base.ref == "develop"
+                and .user.login == "dependabot[bot]"
+                and .head.repo.full_name == $repo
+                and .head.sha == $sha)]
+              | if length == 1 then .[0].head.ref else empty end')
+          if [[ ! "$head_ref" =~ ^dependabot/[A-Za-z0-9._/@+-]+$ ]]; then
+            echo "::error::No open Dependabot PR into develop has head commit ${HEAD_SHA}."
+            exit 1
+          fi
+          echo "head_ref=${head_ref}" >> "$GITHUB_OUTPUT"
+
+      - name: Download deduped lockfile
+        if: steps.pr.outputs.head_ref
+        uses: actions/download-artifact@v8
+        with:
+          name: pnpm-lock
+          path: ${{ runner.temp }}/pnpm-lock
+          run-id: ${{ github.event.workflow_run.id }}
+          github-token: ${{ github.token }}
+
+      - name: Check out PR branch
+        if: steps.pr.outputs.head_ref
+        uses: actions/checkout@v7
+        with:
+          ref: ${{ github.event.workflow_run.head_sha }}
+          persist-credentials: false
+
+      # Replace the file instead of writing through it, so a symlinked lockfile in the PR cannot redirect the write.
+      - name: Apply deduped lockfile
+        if: steps.pr.outputs.head_ref
+        id: apply
+        env:
+          LOCKFILE_DIR: ${{ runner.temp }}/pnpm-lock
+        run: |
+          if [ "$(find "$LOCKFILE_DIR" -mindepth 1 | wc -l)" != "1" ] || [ ! -f "$LOCKFILE_DIR/pnpm-lock.yaml" ] || [ -L "$LOCKFILE_DIR/pnpm-lock.yaml" ]; then
+            echo "::error::The artifact must contain exactly one regular file named pnpm-lock.yaml."
+            exit 1
+          fi
+          if [ "$(git ls-files --stage -- pnpm-lock.yaml | cut -d' ' -f1)" != "100644" ]; then
+            echo "::error::pnpm-lock.yaml in the PR is not a regular file."
+            exit 1
+          fi
+          rm pnpm-lock.yaml
+          cp "$LOCKFILE_DIR/pnpm-lock.yaml" pnpm-lock.yaml
+
+          changes=$(git status --porcelain)
+          if [ -z "$changes" ]; then
+            echo "Lockfile is already deduped."
+            exit 0
+          fi
+          if [ "$changes" != " M pnpm-lock.yaml" ]; then
+            echo "::error::Unexpected changes:"
+            echo "$changes"
+            exit 1
+          fi
+          echo "changed=true" >> "$GITHUB_OUTPUT"
+
+      # An app token is needed so the push triggers CI again; pushes made with GITHUB_TOKEN do not.
+      - name: Generate GitHub App token
+        if: steps.apply.outputs.changed == 'true'
+        id: app-token
+        uses: actions/create-github-app-token@1b10c78c7865c340bc4f6099eb2f838309f1e8c3 # v3.1.1
+        with:
+          client-id: ${{ vars.GITFLOW_APP_ID }}
+          private-key: ${{ secrets.GITFLOW_APP_PRIVATE_KEY }}
+          permission-contents: write
+
+      # `[dependabot skip]` lets Dependabot keep rebasing the PR over this commit.
+      # The push is not forced, so it fails if the branch moved past HEAD_SHA in the meantime.
+      - name: Commit and push
+        if: steps.apply.outputs.changed == 'true'
+        env:
+          APP_TOKEN: ${{ steps.app-token.outputs.token }}
+          APP_SLUG: ${{ steps.app-token.outputs.app-slug }}
+          HEAD_REF: ${{ steps.pr.outputs.head_ref }}
+        run: |
+          git config user.name "${APP_SLUG}[bot]"
+          git config user.email "${APP_SLUG}[bot]@users.noreply.github.com"
+          git commit -m "chore(deps): Dedupe pnpm-lock.yaml [dependabot skip]" -- pnpm-lock.yaml
+          git push "https://x-access-token:${APP_TOKEN}@github.com/${GITHUB_REPOSITORY}.git" "HEAD:refs/heads/${HEAD_REF}"
diff --git a/.github/workflows/dependabot-dedupe.yml b/.github/workflows/dependabot-dedupe.yml
new file mode 100644
index 000000000000..1232a07c94da
--- /dev/null
+++ b/.github/workflows/dependabot-dedupe.yml
@@ -0,0 +1,60 @@
+name: 'Dependabot: Dedupe lockfile'
+
+# Dependabot updates pnpm-lock.yaml without deduping it, so `Check lockfile` (`pnpm dedupe --check`)
+# fails on most of its PRs. This job dedupes the lockfile and uploads it as an artifact. It runs on
+# `pull_request`, so it has no secrets, a read-only token and PR-scoped caches.
+# `dependabot-dedupe-push.yml` validates the result and pushes it to the PR branch.
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+    branches:
+      - develop
+    paths:
+      - 'pnpm-lock.yaml'
+
+permissions:
+  contents: read
+
+concurrency:
+  group: dependabot-dedupe-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+jobs:
+  dedupe:
+    name: Dedupe lockfile
+    if: |
+      github.event.pull_request.user.login == 'dependabot[bot]'
+      && github.event.pull_request.head.repo.full_name == github.repository
+    # PR code runs here, so keep its cache writes away from the cache used by develop, like the PR jobs in build.yml.
+    runs-on: namespace-profile-sentry-javascript;overrides.cache-tag=sentry-javascript-pr
+    # `pnpm dedupe` fetches metadata for every package from npm.
+    timeout-minutes: 20
+    steps:
+      - name: Check out PR branch
+        uses: actions/checkout@v7
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+          persist-credentials: false
+
+      - name: Install pnpm
+        uses: ./.github/actions/install-pnpm
+
+      - name: Set up Node
+        uses: actions/setup-node@v7
+        with:
+          node-version-file: 'package.json'
+
+      - name: Dedupe lockfile
+        id: dedupe
+        run: |
+          pnpm dedupe --ignore-scripts --ignore-pnpmfile
+          git diff --quiet pnpm-lock.yaml || echo "changed=true" >> "$GITHUB_OUTPUT"
+
+      - name: Upload deduped lockfile
+        if: steps.dedupe.outputs.changed == 'true'
+        uses: actions/upload-artifact@v7
+        with:
+          name: pnpm-lock
+          path: pnpm-lock.yaml
+          retention-days: 1