Add GitHub Actions coverage badge generation

Created coverage badge workflow that:
- Generates coverage.svg badge using coverage-badge package
- Uploads coverage artifacts in main test workflow
- Creates separate coverage-badge workflow that commits badge to repo
- Replaces Codecov dependency with self-contained solution

This enables coverage badge display without external service accounts.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: jeremymanning

.github/workflows/coverage-badge.yml

@@ -0,0 +1,58 @@
+name: Coverage Badge
+
+on:
+  push:
+    branches: [ master ]
+  workflow_run:
+    workflows: ["Tests"]
+    types:
+      - completed
+
+jobs:
+  coverage-badge:
+    runs-on: ubuntu-latest
+    if: github.ref == 'refs/heads/master'
+    
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        persist-credentials: false
+        fetch-depth: 0
+
+    - name: Set up Python 3.11
+      uses: actions/setup-python@v4
+      with:
+        python-version: '3.11'
+
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install -e ".[dev,test]"
+        pip install coverage-badge
+
+    - name: Run tests with coverage
+      run: |
+        pytest tests/ -v --cov=clustrix --cov-report=xml --cov-report=term
+
+    - name: Generate coverage badge
+      run: |
+        coverage-badge -o coverage.svg -f
+
+    - name: Verify badge created
+      run: |
+        ls -la coverage.svg
+        cat coverage.svg | head -5
+
+    - name: Commit badge
+      run: |
+        git config --local user.email "action@github.com"
+        git config --local user.name "GitHub Action"
+        git add coverage.svg
+        git diff --staged --quiet || git commit -m "Update coverage badge" || echo "No changes to commit"
+
+    - name: Push badge
+      uses: ad-m/github-push-action@master
+      with:
+        github_token: ${{ secrets.GITHUB_TOKEN }}
+        branch: master
+        force: false

.github/workflows/tests.yml

@@ -49,14 +49,21 @@ jobs:
       run: |
         pytest tests/ -v --cov=clustrix --cov-report=xml --cov-report=html --cov-report=term-missing
 
-    - name: Upload coverage to Codecov
+    - name: Generate coverage badge
       if: matrix.os == 'ubuntu-latest' && matrix.python-version == '3.11'
-      uses: codecov/codecov-action@v3
+      run: |
+        pip install coverage-badge
+        coverage-badge -o coverage.svg -f
+        
+    - name: Upload coverage report
+      if: matrix.os == 'ubuntu-latest' && matrix.python-version == '3.11'
+      uses: actions/upload-artifact@v4
       with:
-        file: ./coverage.xml
-        flags: unittests
-        name: codecov-umbrella
-        fail_ci_if_error: false
+        name: coverage-report
+        path: |
+          coverage.xml
+          htmlcov/
+          coverage.svg
 
     - name: Test installation
       run: |

clustrix/executor.py

@@ -242,7 +242,86 @@ def _submit_sge_job(
     def _submit_k8s_job(
         self, func_data: Dict[str, Any], job_config: Dict[str, Any]
     ) -> str:
-        """Submit job via Kubernetes."""
+        """
+        Submit a job to Kubernetes cluster using containerized Python execution.
+        
+        This method implements a sophisticated Kubernetes job submission strategy that
+        packages Python functions and data into self-contained container jobs without
+        requiring custom Docker images or persistent storage.
+        
+        **Architecture:**
+        
+        1. **Function Serialization**: Uses cloudpickle to serialize the function and all data
+        2. **Base64 Encoding**: Encodes serialized data for safe embedding in container args
+        3. **Container Execution**: Creates a Job with inline Python code that:
+           - Decodes the base64 data
+           - Deserializes the function and arguments  
+           - Executes the function
+           - Captures results or errors
+        4. **Resource Management**: Applies CPU and memory limits from job_config
+        
+        **Key Features:**
+        - **No Custom Images**: Uses standard `python:3.11-slim` image
+        - **Self-Contained**: All code and data embedded in Job manifest
+        - **Resource Aware**: Respects CPU/memory requirements
+        - **Error Handling**: Captures exceptions with full tracebacks
+        - **Cloud Native**: Leverages Kubernetes Job semantics for reliability
+        
+        **Job Manifest Structure:**
+        ```yaml
+        apiVersion: batch/v1
+        kind: Job
+        metadata:
+          name: clustrix-job-{timestamp}
+        spec:
+          template:
+            spec:
+              containers:
+              - name: clustrix-worker
+                image: python:3.11-slim
+                command: ["python", "-c"]
+                args: ["<embedded Python code>"]
+                resources:
+                  requests/limits: {cpu, memory from job_config}
+              restartPolicy: Never
+        ```
+
+        Args:
+            func_data: Serialized function data containing:
+                      - 'func': The function to execute
+                      - 'args': Positional arguments  
+                      - 'kwargs': Keyword arguments
+                      - 'requirements': Package dependencies (not used for K8s)
+            job_config: Job configuration including:
+                       - 'cores': CPU request/limit (default: 1)
+                       - 'memory': Memory request/limit (default: "1Gi")
+                       - Additional K8s-specific settings
+
+        Returns:
+            str: Kubernetes Job name that can be used for status tracking
+            
+        Raises:
+            ImportError: If kubernetes package is not installed
+            Exception: If Kubernetes API calls fail
+            
+        Examples:
+            >>> func_data = {
+            ...     'func': lambda x: x**2,
+            ...     'args': (5,),
+            ...     'kwargs': {},
+            ...     'requirements': {}
+            ... }
+            >>> job_config = {'cores': 2, 'memory': '4Gi'}
+            >>> job_id = executor._submit_k8s_job(func_data, job_config)
+            >>> print(job_id)  # "clustrix-job-1234567890"
+            
+        Note:
+            - Requires kubernetes package: `pip install kubernetes`
+            - Assumes kubectl is configured with cluster access
+            - Jobs are created in the "default" namespace
+            - Cloudpickle is used for function serialization
+            - Results are captured via stdout parsing (CLUSTRIX_RESULT: prefix)
+        """
         try:
             from kubernetes import client, config as k8s_config
         except ImportError: