diff --git a/.github/workflows/docker-build.yml b/.github/workflows/docker-build.yml
index 6e0df06..29cb0c6 100644
--- a/.github/workflows/docker-build.yml
+++ b/.github/workflows/docker-build.yml
@@ -70,6 +70,16 @@ on:
       trivy-ignore-unfixed:
         type: boolean
         default: true
+      upload-sarif:
+        description: >-
+          Upload the Trivy SARIF report to code scanning. Requires GitHub
+          Advanced Security, so private repos on the Free plan must pass false —
+          otherwise the upload step fails with "Advanced Security must be
+          enabled for this repository to use code scanning" while the scan
+          itself passes. Mirrors the input of the same name on trivy-repo.yml.
+          Defaults true to preserve existing behaviour.
+        type: boolean
+        default: true
       sign-image:
         description: "Sign the pushed image with cosign keyless OIDC. Requires push: true."
         type: boolean
@@ -115,7 +125,17 @@ jobs:
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
 
+      # QEMU only exists to emulate a foreign architecture. The runners are all
+      # X64 and `platforms` defaults to linux/amd64, so for most consumers this
+      # step installs binfmt handlers that nothing then uses — while costing real
+      # wall-clock on a contended pool: 16m18s observed on one extractor-llm
+      # run, ahead of a build that never needed it.
+      #
+      # Skipped when the requested platforms are exactly the native arch. The
+      # two consumers that do cross-build (scraper-proxy-router always, store-s3
+      # on main) pass a platforms list containing linux/arm64 and still get it.
       - uses: docker/setup-qemu-action@96fe6ef7f33517b61c61be40b68a1882f3264fb8 # v4.2.0
+        if: inputs.platforms != 'linux/amd64'
       - uses: docker/setup-buildx-action@37fe631027851001ddb9b187196cc803df7f5f0e # v4.3.0
 
       # Mint a scoped App token for private modules pulled during the build.
@@ -226,8 +246,14 @@ jobs:
           severity: ${{ inputs.trivy-severity }}
           ignore-unfixed: ${{ inputs.trivy-ignore-unfixed }}
 
+      # Guarded by `upload-sarif` for the same reason trivy-repo.yml is: uploading
+      # to code scanning needs GitHub Advanced Security, which private repos on
+      # the Free plan do not have. Without the guard the step fails with
+      # "Advanced Security must be enabled for this repository to use code
+      # scanning" on every push to main, while the scan above passes — a
+      # permanently red check reporting an entitlement rather than a finding.
       - name: Trivy scan (SARIF)
-        if: inputs.run-trivy-scan && inputs.push && github.event_name != 'pull_request'
+        if: inputs.run-trivy-scan && inputs.push && inputs.upload-sarif && github.event_name != 'pull_request'
         uses: aquasecurity/trivy-action@ed142fd0673e97e23eac54620cfb913e5ce36c25 # v0.36.0
         with:
           image-ref: ${{ steps.imageref.outputs.repo }}@${{ steps.build.outputs.digest }}
@@ -237,7 +263,7 @@ jobs:
           ignore-unfixed: ${{ inputs.trivy-ignore-unfixed }}
 
       - name: Upload SARIF
-        if: inputs.run-trivy-scan && inputs.push && github.event_name != 'pull_request'
+        if: inputs.run-trivy-scan && inputs.push && inputs.upload-sarif && github.event_name != 'pull_request'
         uses: github/codeql-action/upload-sarif@cdf488f595d80d6e07e03d4674febd5ab45fa938 # v4.37.9
         with:
           sarif_file: trivy.sarif
diff --git a/CHANGELOG.md b/CHANGELOG.md
index fceb802..e8ccd5f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,33 @@ project uses [SemVer](https://semver.org/) for the `vMAJOR.MINOR.PATCH` tags.
 
 ## [Unreleased]
 
+### Added
+
+- **`docker-build.yml` gained an `upload-sarif` input** (boolean, default
+  `true`, mirroring the input of the same name on `trivy-repo.yml`). Uploading
+  a SARIF report to code scanning requires GitHub Advanced Security, which
+  private repos on the Free plan do not have, so the `Upload SARIF` step failed
+  with `Advanced Security must be enabled for this repository to use code
+  scanning` on every push to `main` while the Trivy scan immediately above it
+  passed. That is a permanently red check reporting an entitlement rather than
+  a security finding. Consumers on the Free plan pass `upload-sarif: false`;
+  the SARIF generation step is gated on the same input, so nothing is produced
+  that cannot be uploaded. Default is `true`, so existing behaviour is
+  unchanged for anyone who has Advanced Security.
+
+### Fixed
+
+- **`docker-build.yml` no longer runs `docker/setup-qemu-action` for
+  single-architecture builds.** QEMU exists only to emulate a foreign
+  architecture; the runners are all X64 and `platforms` defaults to
+  `linux/amd64`, so for most consumers the step installed binfmt handlers that
+  nothing subsequently used. It is not free: **16m18s** on one observed
+  `extractor-llm` run, ahead of a build that never needed it, on a three-runner
+  pool where queueing is the dominant cost. The step is now skipped when
+  `platforms` is exactly `linux/amd64`. The two consumers that genuinely
+  cross-build — `scraper-proxy-router` (always) and `store-s3` (on `main`) —
+  request `linux/arm64` and still get QEMU.
+
 ### Changed
 
 - **`claude-code-review.yml` now defaults to a GitHub-hosted runner**