diff --git a/.github/workflows/actions-lint.yaml b/.github/workflows/actions-lint.yaml
index 391d8bf..f30a1c6 100644
--- a/.github/workflows/actions-lint.yaml
+++ b/.github/workflows/actions-lint.yaml
@@ -31,7 +31,11 @@ env:
 jobs:
   actionlint:
     name: actionlint and shellcheck
-    runs-on: ubuntu-latest
+    runs-on: >-
+      ${{ (github.event_name != 'pull_request'
+      || github.event.pull_request.head.repo.full_name == github.repository)
+      && format('gcrunner={0}-actionlint-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index)
+      || 'ubuntu-latest' }}
     steps:
       - uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
         with:
@@ -60,7 +64,11 @@ jobs:
 
   zizmor:
     name: zizmor
-    runs-on: ubuntu-latest
+    runs-on: >-
+      ${{ (github.event_name != 'pull_request'
+      || github.event.pull_request.head.repo.full_name == github.repository)
+      && format('gcrunner={0}-zizmor-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index)
+      || 'ubuntu-latest' }}
     steps:
       - uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
         with:
diff --git a/.github/workflows/e2e-nightly.yaml b/.github/workflows/e2e-nightly.yaml
index a8e5ae4..bb51be8 100644
--- a/.github/workflows/e2e-nightly.yaml
+++ b/.github/workflows/e2e-nightly.yaml
@@ -18,7 +18,7 @@ env:
 jobs:
   functions:
     name: Functions and optional components
-    runs-on: ubuntu-latest
+    runs-on: ${{ format('gcrunner={0}-functions-{1}/machine=c3d-standard-8', github.run_id, strategy.job-index) }}
     timeout-minutes: 60
     steps:
       - uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
diff --git a/.github/workflows/lint.yaml b/.github/workflows/lint.yaml
index 7aa7c6e..9fcd047 100644
--- a/.github/workflows/lint.yaml
+++ b/.github/workflows/lint.yaml
@@ -23,7 +23,11 @@ env:
 jobs:
   lint:
     name: Lint (Helm ${{ matrix.helm }})
-    runs-on: ubuntu-latest
+    runs-on: >-
+      ${{ (github.event_name != 'pull_request'
+      || github.event.pull_request.head.repo.full_name == github.repository)
+      && format('gcrunner={0}-lint-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index)
+      || 'ubuntu-latest' }}
     strategy:
       fail-fast: false
       matrix:
@@ -58,7 +62,11 @@ jobs:
 
   unittest:
     name: Unit tests (Helm ${{ matrix.helm }})
-    runs-on: ubuntu-latest
+    runs-on: >-
+      ${{ (github.event_name != 'pull_request'
+      || github.event.pull_request.head.repo.full_name == github.repository)
+      && format('gcrunner={0}-unittest-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index)
+      || 'ubuntu-latest' }}
     strategy:
       fail-fast: false
       matrix:
@@ -96,7 +104,11 @@ jobs:
 
   kubeconform:
     name: kubeconform
-    runs-on: ubuntu-latest
+    runs-on: >-
+      ${{ (github.event_name != 'pull_request'
+      || github.event.pull_request.head.repo.full_name == github.repository)
+      && format('gcrunner={0}-kubeconform-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index)
+      || 'ubuntu-latest' }}
     steps:
       - uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
         with:
@@ -118,7 +130,11 @@ jobs:
 
   generated:
     name: Generated files are up to date
-    runs-on: ubuntu-latest
+    runs-on: >-
+      ${{ (github.event_name != 'pull_request'
+      || github.event.pull_request.head.repo.full_name == github.repository)
+      && format('gcrunner={0}-generated-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index)
+      || 'ubuntu-latest' }}
     steps:
       - uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
         with:
@@ -139,7 +155,11 @@ jobs:
 
   metadata:
     name: Chart metadata
-    runs-on: ubuntu-latest
+    runs-on: >-
+      ${{ (github.event_name != 'pull_request'
+      || github.event.pull_request.head.repo.full_name == github.repository)
+      && format('gcrunner={0}-metadata-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index)
+      || 'ubuntu-latest' }}
     steps:
       - uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
         with:
@@ -152,10 +172,16 @@ jobs:
 
   artifacthub:
     name: Artifact Hub lint
-    runs-on: ubuntu-latest
-    container:
-      image: docker.io/artifacthub/ah:v1.23.0@sha256:e5d2a2cdef85aac4928e8176ffaad24746c5fe961d64ff6856f7222957095356
-      options: --user 1001
+    runs-on: >-
+      ${{ (github.event_name != 'pull_request'
+      || github.event.pull_request.head.repo.full_name == github.repository)
+      && format('gcrunner={0}-artifacthub-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index)
+      || 'ubuntu-latest' }}
+    env:
+      # Run from the image, pinned by digest, with the runner's own uid: as a
+      # job container, its user has to match the runner's to write the
+      # runner's files, and that uid differs between runners.
+      AH_IMAGE: docker.io/artifacthub/ah:v1.23.0@sha256:e5d2a2cdef85aac4928e8176ffaad24746c5fe961d64ff6856f7222957095356
     steps:
       - uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
         with:
@@ -164,12 +190,15 @@ jobs:
         with:
           persist-credentials: false
       - name: ah lint
-        working-directory: charts
-        run: ah lint
+        run: docker run --rm -u "$(id -u):$(id -g)" -v "${GITHUB_WORKSPACE}/charts:/charts:ro" -w /charts "$AH_IMAGE" ah lint
 
   changelog:
     name: Changelog
-    runs-on: ubuntu-latest
+    runs-on: >-
+      ${{ (github.event_name != 'pull_request'
+      || github.event.pull_request.head.repo.full_name == github.repository)
+      && format('gcrunner={0}-changelog-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index)
+      || 'ubuntu-latest' }}
     steps:
       - uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
         with:
diff --git a/.github/workflows/renovate-generate.yaml b/.github/workflows/renovate-generate.yaml
index 42bee1a..8ee18aa 100644
--- a/.github/workflows/renovate-generate.yaml
+++ b/.github/workflows/renovate-generate.yaml
@@ -32,7 +32,11 @@ jobs:
     # The pull request's author, which a later pusher can't change. Forks
     # never get here: Renovate pushes branches to this repository.
     if: github.event.pull_request.user.login == 'renovate[bot]' && github.event.pull_request.head.repo.full_name == github.repository
-    runs-on: ubuntu-latest
+    runs-on: >-
+      ${{ (github.event_name != 'pull_request'
+      || github.event.pull_request.head.repo.full_name == github.repository)
+      && format('gcrunner={0}-generate-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index)
+      || 'ubuntu-latest' }}
     permissions:
       contents: read
     steps:
diff --git a/.github/workflows/security-scan.yaml b/.github/workflows/security-scan.yaml
index 9500097..de6117a 100644
--- a/.github/workflows/security-scan.yaml
+++ b/.github/workflows/security-scan.yaml
@@ -19,7 +19,7 @@ env:
 jobs:
   prepare:
     name: Images and visibility
-    runs-on: ubuntu-latest
+    runs-on: ${{ format('gcrunner={0}-prepare-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index) }}
     outputs:
       images: ${{ steps.images.outputs.images }}
       public: ${{ steps.repo.outputs.public }}
@@ -49,7 +49,7 @@ jobs:
   images:
     name: Image ${{ matrix.image.name }}
     needs: prepare
-    runs-on: ubuntu-latest
+    runs-on: ${{ format('gcrunner={0}-images-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index) }}
     permissions:
       contents: read
       security-events: write
@@ -86,7 +86,7 @@ jobs:
   config:
     name: Rendered manifests
     needs: prepare
-    runs-on: ubuntu-latest
+    runs-on: ${{ format('gcrunner={0}-config-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index) }}
     permissions:
       contents: read
       security-events: write
diff --git a/.github/workflows/test-install.yaml b/.github/workflows/test-install.yaml
index 9d1166f..33d3374 100644
--- a/.github/workflows/test-install.yaml
+++ b/.github/workflows/test-install.yaml
@@ -30,7 +30,11 @@ concurrency:
 jobs:
   install:
     name: ${{ matrix.scenario }} (k8s ${{ matrix.kubernetes }})${{ matrix.upgrade-from && format(' upgrade from {0}', matrix.upgrade-from) || '' }}
-    runs-on: ubuntu-latest
+    runs-on: >-
+      ${{ (github.event_name != 'pull_request'
+      || github.event.pull_request.head.repo.full_name == github.repository)
+      && format('gcrunner={0}-install-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index)
+      || 'ubuntu-latest' }}
     timeout-minutes: 45
     strategy:
       fail-fast: false
@@ -168,7 +172,11 @@ jobs:
     name: Install result
     needs: install
     if: always()
-    runs-on: ubuntu-latest
+    runs-on: >-
+      ${{ (github.event_name != 'pull_request'
+      || github.event.pull_request.head.repo.full_name == github.repository)
+      && format('gcrunner={0}-result-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index)
+      || 'ubuntu-latest' }}
     permissions: {}
     steps:
       - uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
diff --git a/.github/workflows/upstream-drift.yaml b/.github/workflows/upstream-drift.yaml
index f1f4939..aa1d5f8 100644
--- a/.github/workflows/upstream-drift.yaml
+++ b/.github/workflows/upstream-drift.yaml
@@ -12,7 +12,7 @@ permissions:
 
 jobs:
   check:
-    runs-on: ubuntu-latest
+    runs-on: ${{ format('gcrunner={0}-check-{1}/machine=c3d-standard-4', github.run_id, strategy.job-index) }}
     permissions:
       contents: read
       issues: write   # open the drift issue
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 34d9a40..2db945b 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -105,6 +105,20 @@ The scenarios CI installs are the `charts/appwrite/ci/*-values.yaml` files.
 | [Upstream drift](.github/workflows/upstream-drift.yaml) | weekly | opens an issue when Appwrite releases a version the chart doesn't ship |
 | [Release](.github/workflows/release.yaml) | `Chart.yaml` changes on `main` | see [RELEASING.md](RELEASING.md) |
 
+Jobs run on Appwrite's [gcrunner](https://github.com/appwrite-labs/gcrunner)
+runners: an ephemeral Compute Engine VM per job, picked with
+`runs-on: gcrunner=<run id>-<job>-<index>/machine=<type>` (c3d-standard-8
+for the nightly, c3d-standard-4 otherwise). Pull requests from forks ask for
+GitHub-hosted runners instead. That isn't a security boundary: a pull request
+runs its own copy of the workflow, so a fork can ask for gcrunner, and
+gcrunner doesn't check where a job comes from. While the repository is
+public, the guard is that a maintainer approves every workflow run from a
+fork pull request (Settings → Actions → General → "Require approval for all
+external contributors") after reading its workflow changes; never approve a
+fork's run that changes `runs-on`. Release and Scorecard stay on GitHub-hosted
+runners: Scorecard only publishes results from them, and the release's
+signature and provenance attestation name the runner that built the chart.
+
 Workflows pin every action to a commit SHA (with the version in a comment)
 and every tool to a version in `env:`, which Renovate updates through the
 custom managers in `renovate.json`. A new pinned tool needs a manager there.
diff --git a/renovate.json b/renovate.json
index 6ffa8c9..f916682 100644
--- a/renovate.json
+++ b/renovate.json
@@ -204,13 +204,13 @@
       "extractVersionTemplate": "^v(?<version>.*)$"
     },
     {
-      "description": "Trivy image (tag and digest) in the security scan workflow",
+      "description": "Images run with docker run in the workflows (tag and digest): Trivy and Artifact Hub's ah",
       "customType": "regex",
       "managerFilePatterns": [
         "/^\\.github/workflows/.+\\.ya?ml$/"
       ],
       "matchStrings": [
-        "TRIVY_IMAGE:\\s*(?<depName>[^:\\s]+):(?<currentValue>[^@\\s]+)@(?<currentDigest>sha256:[a-f0-9]{64})"
+        "(?:TRIVY|AH)_IMAGE:\\s*(?<depName>[^:\\s]+):(?<currentValue>[^@\\s]+)@(?<currentDigest>sha256:[a-f0-9]{64})"
       ],
       "datasourceTemplate": "docker"
     }