ci: auto-rerun daily pipeline on runner allocation failure

When GitHub's hosted runner pool fails to acquire a runner (job ends
with the "not acquired by Runner of type hosted" annotation), retry
the failed jobs once. Other failure modes are left alone so real
breakage still surfaces.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: costajohnt

.github/workflows/auto-rerun-allocation-failure.yml

@@ -0,0 +1,52 @@
+# Reruns Daily Trading Pipeline when GitHub's hosted runner pool fails to
+# acquire a runner (annotation: "not acquired by Runner of type hosted...").
+# Other failure types are left alone. Guarded to first attempt only to
+# prevent rerun loops.
+name: Auto-rerun on Runner Allocation Failure
+
+on:
+  workflow_run:
+    workflows: ["Daily Trading Pipeline"]
+    types: [completed]
+
+permissions:
+  actions: write
+
+jobs:
+  rerun:
+    if: ${{ github.event.workflow_run.conclusion == 'failure' && github.event.workflow_run.run_attempt == 1 }}
+    runs-on: ubuntu-latest
+    steps:
+      - name: Detect runner allocation failure
+        id: detect
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          REPO: ${{ github.repository }}
+          RUN_ID: ${{ github.event.workflow_run.id }}
+        run: |
+          set -euo pipefail
+          allocation_failure=false
+          job_ids=$(gh api "/repos/$REPO/actions/runs/$RUN_ID/jobs" --jq '.jobs[].id')
+          for job_id in $job_ids; do
+            annotations=$(gh api "/repos/$REPO/check-runs/$job_id/annotations" 2>/dev/null || echo '[]')
+            if echo "$annotations" | jq -e 'any(.[]; .message | test("not acquired by Runner"))' >/dev/null; then
+              allocation_failure=true
+              echo "Runner allocation failure detected on job $job_id"
+              break
+            fi
+          done
+          echo "allocation_failure=$allocation_failure" >> "$GITHUB_OUTPUT"
+
+      - name: Rerun failed jobs
+        if: steps.detect.outputs.allocation_failure == 'true'
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          REPO: ${{ github.repository }}
+          RUN_ID: ${{ github.event.workflow_run.id }}
+        run: |
+          gh run rerun --repo "$REPO" "$RUN_ID" --failed
+          echo "Triggered rerun of run $RUN_ID"
+
+      - name: Skip (not a runner allocation failure)
+        if: steps.detect.outputs.allocation_failure != 'true'
+        run: echo "Failure not caused by runner allocation; no rerun triggered."