diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6b447291..9350f114 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -235,7 +235,13 @@ jobs:
         run: npx vitest run --coverage
       - name: Upload coverage summary as artifact
         if: needs.changes.outputs.canvas == 'true' && always()
-        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        # Pinned to v3 for Gitea act_runner v0.6 compatibility — v4+ uses
+        # the GHES 3.10+ artifact protocol that Gitea 1.22.x does NOT
+        # implement, surfacing as `GHESNotSupportedError: @actions/artifact
+        # v2.0.0+, upload-artifact@v4+ and download-artifact@v4+ are not
+        # currently supported on GHES`. Drop this pin when Gitea ships
+        # the v4 protocol (tracked: post-Gitea-1.23 followup).
+        uses: actions/upload-artifact@c6a366c94c3e0affe28c06c8df20a878f24da3cf # v3.2.2
         with:
           name: canvas-coverage-${{ github.run_id }}
           path: canvas/coverage/
diff --git a/.github/workflows/e2e-staging-canvas.yml b/.github/workflows/e2e-staging-canvas.yml
index 0bc152df..30a38e5f 100644
--- a/.github/workflows/e2e-staging-canvas.yml
+++ b/.github/workflows/e2e-staging-canvas.yml
@@ -139,7 +139,11 @@ jobs:
 
       - name: Upload Playwright report on failure
         if: failure() && needs.detect-changes.outputs.canvas == 'true'
-        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        # Pinned to v3 for Gitea act_runner v0.6 compatibility — v4+ uses
+        # the GHES 3.10+ artifact protocol that Gitea 1.22.x does NOT
+        # implement (see ci.yml upload step for the canonical error
+        # cite). Drop this pin when Gitea ships the v4 protocol.
+        uses: actions/upload-artifact@c6a366c94c3e0affe28c06c8df20a878f24da3cf # v3.2.2
         with:
           name: playwright-report-staging
           path: canvas/playwright-report-staging/
@@ -147,7 +151,8 @@ jobs:
 
       - name: Upload screenshots on failure
         if: failure() && needs.detect-changes.outputs.canvas == 'true'
-        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        # Pinned to v3 for Gitea act_runner v0.6 compatibility (see above).
+        uses: actions/upload-artifact@c6a366c94c3e0affe28c06c8df20a878f24da3cf # v3.2.2
         with:
           name: playwright-screenshots
           path: canvas/test-results/