add openapi snapshotting to CI pipeline

.github/workflows/check-lazy-openapi-snapshot.yml

@@ -0,0 +1,75 @@
+name: Check Lazy OpenAPI Snapshot
+
+on:
+  pull_request:
+    branches:
+      - main
+      - litellm_internal_staging
+      - "litellm_**"
+
+permissions:
+  contents: read
+  checks: write
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  verify:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@08eba0b27e820071cde6df949e0beb9ba4906955 # v4.3.0
+        with:
+          persist-credentials: false
+
+      - name: Set up Python
+        uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5.6.0
+        with:
+          python-version: "3.12"
+
+      - name: Set up uv
+        uses: astral-sh/setup-uv@37802adc94f370d6bfd71619e3f0bf239e1f3b78 # v7
+        with:
+          version: "0.10.9"
+
+      - name: Cache uv dependencies
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
+        with:
+          path: |
+            ~/.cache/uv
+            .venv
+          key: ${{ runner.os }}-uv-${{ hashFiles('uv.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-uv-
+
+      - name: Install dependencies
+        run: uv sync --frozen --all-groups --all-extras
+
+      - name: Regenerate snapshot to /tmp
+        id: regen
+        run: |
+          cp litellm/proxy/_lazy_openapi_snapshot.json /tmp/snapshot.committed.json
+          uv run --no-sync python -m litellm.proxy._lazy_openapi_snapshot
+          mv litellm/proxy/_lazy_openapi_snapshot.json /tmp/snapshot.fresh.json
+          mv /tmp/snapshot.committed.json litellm/proxy/_lazy_openapi_snapshot.json
+
+      - name: Compare
+        id: diff
+        continue-on-error: true
+        run: |
+          diff -q /tmp/snapshot.fresh.json litellm/proxy/_lazy_openapi_snapshot.json
+
+      - name: Mark neutral if drift
+        if: steps.diff.outcome == 'failure'
+        uses: LouisBrunner/checks-action@v2.0.0
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          name: lazy-openapi-snapshot
+          conclusion: neutral
+          output: |
+            {
+              "title": "Lazy openapi snapshot is stale",
+              "summary": "Run `python -m litellm.proxy._lazy_openapi_snapshot` and commit the regenerated `litellm/proxy/_lazy_openapi_snapshot.json`. Not blocking — the snapshot will regenerate at release if not committed."
+            }