fix(ci): pre-download iscc-sct model to prevent race conditions

Add model caching and pre-download steps to prevent parallel test
failures caused by concurrent model downloads. Model download race
conditions were corrupting the ONNX file, causing INVALID_PROTOBUF
errors in GitHub Actions tests.

CI Changes:
- Cache ~/.local/share/iscc-sct between GitHub Actions runs
- Pre-download model before running parallel tests (pytest -n auto)

Docker Changes:
- Pre-download model during Docker build in builder stage
- Copy model from builder to runtime stage
- Eliminates model download on container startup (~200-300 MB)

Fixes test failures where multiple pytest workers simultaneously
attempted to download the model to the same location.

Related upstream issues filed on iscc/iscc-sct:
- #18: Add file locking during model download
- #19: Add configurable model storage path
- #20: Add CLI command to pre-download models

Author: titusz

.github/workflows/docker-publish.yml

@@ -21,6 +21,18 @@ jobs:
         with:
           python-version: "3.12"
 
+      - name: Cache iscc-sct model
+        uses: actions/cache@v4
+        with:
+          path: ~/.local/share/iscc-sct
+          key: iscc-sct-model-${{ hashFiles('**/pyproject.toml') }}
+          restore-keys: |
+            iscc-sct-model-
+
+      - name: Pre-download iscc-sct model
+        run: |
+          uv run python -c "import iscc_sct.code_semantic_text as sct; sct.model()"
+
       - name: Run tests
         run: uv run poe test
 

Dockerfile

@@ -30,6 +30,11 @@ COPY . .
 # This creates compiled bytecode and optimized install
 RUN uv sync --locked --no-editable --no-dev
 
+# Pre-download iscc-sct model weights during build
+# This ensures the model is available immediately on container start
+# Model is downloaded to ~/.local/share/iscc-sct/ during build
+RUN .venv/bin/python -c "import iscc_sct.code_semantic_text as sct; sct.model()"
+
 
 # Stage 2: Runtime - minimal production image
 FROM python:3.12-slim
@@ -47,6 +52,9 @@ COPY --from=builder /app/iscc_search /app/iscc_search
 # Copy OpenAPI schema files (needed by the app)
 COPY --from=builder /app/iscc_search/openapi /app/iscc_search/openapi
 
+# Copy pre-downloaded iscc-sct model from builder
+COPY --from=builder /root/.local/share/iscc-sct /root/.local/share/iscc-sct
+
 # Add virtual environment to PATH
 ENV PATH="/app/.venv/bin:$PATH"