AP-25351: Add copilot instructions

AP-25351 (Add GitHub Actions for repositories containing scripting editors)

Author: HedgehogCode

.github/copilot-instructions.md

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+# KNIME Python Integration
+
+Hybrid Java/Python/JavaScript codebase bridging KNIME Analytics Platform with Python via Py4J and Apache Arrow.
+
+## Architecture Overview
+
+**Components**:
+- `org.knime.python3*`: OSGi plugins (Eclipse bundles with `META-INF/MANIFEST.MF`)
+- `org.knime.python3.scripting.nodes/js-src/`: Vue 3 scripting editor
+- `knime-extension/`: Conda package for Python node development
+
+**Java-Python Bridge**: Py4J enables bidirectional communication. Java spawns Python processes via `PythonGateway`; Python extends `EntryPoint` classes to expose functionality.
+
+**Data Transfer**: Apache Arrow IPC format via memory-mapped files. Tables serialized through `PythonArrowDataSource`/`PythonArrowDataSink`, metadata (types/domain) passed as JSON.
+
+**Node Extension Flow**:
+1. Python defines nodes with `@knext.node`/`@knext.parameter` decorators
+2. Java's `PurePythonNodeSetFactory` discovers them via Py4J at KNIME startup
+3. `DelegatingNodeModel` proxies execution to Python via `NodeProxy` interfaces
+4. Data flows through Arrow, callbacks through Py4J (e.g., `LogCallback`, `AuthCallback`)
+
+## Module Structure
+
+```
+org.knime.python3           # Core Py4J gateway
+org.knime.python3.arrow     # Arrow data transfer (Java)
+org.knime.python3.arrow.types  # KNIME types (Python)
+org.knime.python3.nodes     # Node framework (Java)
+org.knime.python3.scripting # Scripting infrastructure
+org.knime.python3.scripting.nodes  # Script nodes + Vue editor
+org.knime.python3.views     # Python view rendering
+org.knime.ext.py4j          # Py4J OSGi wrapper
+*.py4j.dependencies         # Expose classes to py4j classloader (don't merge!)
+```
+
+## Quick Start
+
+```bash
+pixi install                # Setup Python env (.pixi/envs/default)
+pixi run test-all           # Python tests (interactive env)
+mvn clean verify            # Java tests
+cd org.knime.python3.scripting.nodes/js-src && npm ci && npm run coverage  # JS tests
+```
+
+## CI/CD
+
+- **Jenkinsfile**: Primary CI
+- **GitHub Actions**: Fast pre-checks: lint, test, build JS, format Python

.github/instructions/java.instructions.md

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+---
+applyTo: "**/*.java"
+---
+# Java Development - KNIME Python Integration
+
+## Build System (Tycho, NOT Standard Maven)
+```bash
+mvn clean verify    # Full build + tests (Tycho 4.0.13 in .mvn/extensions.xml)
+```
+
+**P2 Dependencies** (root `pom.xml`): Dependencies from Eclipse P2 repos, NOT Maven Central.
+
+## Repository-Specific Conventions
+- **OSGi bundles**: Each `org.knime.*` folder has `META-INF/MANIFEST.MF` + `build.properties`
+- **Test bundles**: Name ends `.tests`, use `eclipse-test-plugin` packaging
+- **Test POMs**: Require `org.knime.features.clfixes`, Arrow tests need `org.knime.features.core.columnar`
+- **Critical**: `*.py4j.dependencies` bundles expose classes to py4j classloader - **don't merge!**
+
+## Key Classes (Repository-Specific)
+- `PythonGateway`: Spawns Python processes
+- `PythonArrowDataSource`/`Sink`: Arrow I/O with Python (temp files, metadata as JSON)
+- `DelegatingNodeModel`: Proxies node execution to Python
+- `PurePythonNodeSetFactory`: Discovers Python nodes via Py4J at startup
+- `QueuedPythonGatewayFactory`: Gateway lifecycle singleton
+
+## Common Pitfalls
+1. **P2 only**: Can't use Maven Central deps
+2. **OSGi classloading**: Keep `*.py4j.dependencies` separate
+3. **Test failures**: Missing `org.knime.features.clfixes` in test POM
+4. **Bundle exports**: Explicitly list in `MANIFEST.MF`

.github/instructions/javascript.instructions.md

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+---
+applyTo: "org.knime.python3.scripting.nodes/js-src/**"
+---
+# JavaScript/TypeScript Development - KNIME Python Integration
+
+## Location
+`org.knime.python3.scripting.nodes/js-src/` - Python scripting editor dialog
+
+## Setup
+```bash
+cd org.knime.python3.scripting.nodes/js-src
+npm ci              # Node 22.11.0, npm 10.9.1
+npm run coverage    # Tests + coverage (do not use `npm run test:unit` - it's interactive)
+```
+
+## Repository-Specific Conventions
+- **Maven integration**: `frontend-maven-plugin` runs npm during Maven build
+- **Dependency**: Uses `@knime/scripting-editor` - unlink before committing if testing local changes
+
+## KNIME Dev Mode
+Start KNIME with:
+```
+-Dchromium.remote_debugging_port=8988
+-Dorg.knime.ui.dev.node.dialog.url=http://localhost:5173/
+```
+Then: `npm run dev:knime`

.github/instructions/python.instructions.md

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+---
+applyTo: "**/*.py"
+---
+# Python Development - KNIME Python Integration
+
+## Dependencies & Testing
+```bash
+pixi install          # Setup .pixi/envs/default
+pixi run test-all     # Test across py38-py314, KNIME 4.7-5.6
+pixi run format       # Ruff (target: Python 3.8)
+```
+
+**All dependencies via `pixi.toml`** - never pip/conda directly.
+
+## Repository-Specific Conventions
+- **Path setup**: Root `conftest.py` adds all plugin paths to `sys.path` - **never modify `sys.path` in tests**
+- **Test style**: Function-based tests only (`pytest.ini` disables class discovery)
+- **Multi-version**: Changes must work across Python 3.8-3.14 - test with `pixi run test-all`
+- **PyArrow versions**: Tightly coupled to Python version in `pixi.toml` - don't update independently
+
+## Key Modules (Repository-Specific)
+- `knext`: Node extension decorators (`@knext.node`, `@knext.parameter`)
+- `knime.scripting`: Script API (replaces deprecated `knime_io`, `knime_jupyter`)
+- `knime._arrow._backend`: Arrow I/O with Java (via Py4J)
+
+## Py4J Integration
+- Extend Java `EntryPoint` classes to expose Python to Java
+- Implement Java interfaces for callbacks (`LogCallback`, `AuthCallback`)
+- Arrow data via temp files (IPC format), metadata as JSON
+
+## Debugging
+- `KNIME_PYTHON_DEBUG=true` for gateway logs
+- Import failures: check `conftest.py`