Use a short SPDX license header where applicable; standard lic elsewhere

- Mark .github as export-ignore in .gitattributes
- Add short and long license templates for pre-commit hooks
- Add pre-commit hooks to enforce license headers (replaces CI scripts)
- Delete scripts/add_license_headers.py and scripts/check_license_headers.py
- Remove CI license check step from hamilton-lsp workflow
- Fix inconsistent license header indentation in several files
- Add missing license headers to PR templates
- Add vendored code attributions (Open Law Library, Palantir) to NOTICE file
- Exclude contrib/docs/ from markdown license hook (Docusaurus frontmatter)

Author: Dev-iL

.asf.yaml

@@ -1,3 +1,20 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
 # https://cwiki.apache.org/confluence/display/INFRA/Git+-+.asf.yaml+features
 
 github:

.claude-plugin/skills/core/SKILL.md

@@ -1,29 +1,11 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements.  See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership.  The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License.  You may obtain a copy of the License at
-
-  http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied.  See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-
 ---
 name: hamilton-core
 description: Core Hamilton patterns for creating DAGs, applying decorators, testing, and debugging dataflows. Use for basic Hamilton development tasks.
 allowed-tools: Read, Grep, Glob, Bash(python:*), Bash(pytest:*)
 user-invocable: true
 disable-model-invocation: false
 ---
+<!-- SPDX-License-Identifier: Apache-2.0 -->
 
 # Hamilton Core Development Assistant
 

.claude-plugin/skills/hamilton-dev-workflow/SKILL.md

@@ -1,29 +1,11 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements.  See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership.  The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License.  You may obtain a copy of the License at
-
-  http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied.  See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-
 ---
 name: hamilton-dev-workflow
 description: Systematic 5-step workflow for building Hamilton DAGs - DOT graphs, signatures, validation, TDD implementation. Use this workflow when creating new Hamilton modules from scratch.
 allowed-tools: Read, Grep, Glob, Bash(python:*), Bash(hamilton:*), Bash(pytest:*)
 user-invocable: true
 disable-model-invocation: false
 ---
+<!-- SPDX-License-Identifier: Apache-2.0 -->
 
 # Hamilton Development Workflow for Claude Code
 

.claude-plugin/skills/integrations/SKILL.md

@@ -1,29 +1,11 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements.  See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership.  The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License.  You may obtain a copy of the License at
-
-  http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied.  See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-
 ---
 name: hamilton-integrations
 description: Hamilton integration patterns for Airflow, Dagster, FastAPI, Streamlit, Jupyter notebooks, and other frameworks. Use when integrating Hamilton with other tools.
 allowed-tools: Read, Grep, Glob, Bash(python:*), Bash(jupyter:*)
 user-invocable: true
 disable-model-invocation: false
 ---
+<!-- SPDX-License-Identifier: Apache-2.0 -->
 
 # Hamilton Integrations
 

.claude-plugin/skills/llm/SKILL.md

@@ -1,29 +1,11 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements.  See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership.  The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License.  You may obtain a copy of the License at
-
-  http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied.  See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-
 ---
 name: hamilton-llm
 description: LLM and AI workflow patterns for Hamilton including RAG pipelines, embeddings, vector databases, and prompt engineering. Use for building AI applications with Hamilton.
 allowed-tools: Read, Grep, Glob, Bash(python:*), Bash(pytest:*)
 user-invocable: true
 disable-model-invocation: false
 ---
+<!-- SPDX-License-Identifier: Apache-2.0 -->
 
 # Hamilton for LLM & AI Workflows
 

.claude-plugin/skills/mcp/SKILL.md

@@ -1,29 +1,11 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements.  See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership.  The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License.  You may obtain a copy of the License at
-
-  http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied.  See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-
 ---
 name: hamilton-mcp
 description: Interactive Hamilton DAG development via MCP tools. Validate, visualize, scaffold, and execute Hamilton pipelines without leaving the conversation. Use when building or debugging Hamilton dataflows interactively.
 allowed-tools: Read, Grep, Glob, Bash(hamilton-mcp:*), Bash(python:*), Bash(pip:*)
 user-invocable: true
 disable-model-invocation: false
 ---
+<!-- SPDX-License-Identifier: Apache-2.0 -->
 
 # Hamilton MCP Server -- Interactive DAG Development
 

.claude-plugin/skills/observability/SKILL.md

@@ -1,29 +1,11 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements.  See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership.  The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License.  You may obtain a copy of the License at
-
-  http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied.  See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-
 ---
 name: hamilton-observability
 description: Hamilton UI and SDK patterns for tracking, monitoring, and debugging dataflows. Use for observability, lineage tracking, and production monitoring.
 allowed-tools: Read, Grep, Glob, Bash(python:*), Bash(hamilton:*)
 user-invocable: true
 disable-model-invocation: false
 ---
+<!-- SPDX-License-Identifier: Apache-2.0 -->
 
 # Hamilton Observability & UI
 

.claude-plugin/skills/scale/SKILL.md

@@ -1,29 +1,11 @@
-<!--
-Licensed to the Apache Software Foundation (ASF) under one
-or more contributor license agreements.  See the NOTICE file
-distributed with this work for additional information
-regarding copyright ownership.  The ASF licenses this file
-to you under the Apache License, Version 2.0 (the
-"License"); you may not use this file except in compliance
-with the License.  You may obtain a copy of the License at
-
-  http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing,
-software distributed under the License is distributed on an
-"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-KIND, either express or implied.  See the License for the
-specific language governing permissions and limitations
-under the License.
--->
-
 ---
 name: hamilton-scale
 description: Performance and parallelization patterns for Hamilton including async I/O, Spark, Ray, Dask, caching, and multithreading. Use for scaling Hamilton workflows.
 allowed-tools: Read, Grep, Glob, Bash(python:*), Bash(pytest:*)
 user-invocable: true
 disable-model-invocation: false
 ---
+<!-- SPDX-License-Identifier: Apache-2.0 -->
 
 # Hamilton Scaling & Performance
 

.gitattributes

@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: Apache-2.0
+
+# Files below use a short SPDX license identifier instead of the full
+# Apache 2.0 header because they are NOT included in official releases
+# (sdist / wheel).  The `export-ignore` attribute ensures `git archive`
+# (and tools that rely on it) will exclude them automatically.
+
+.github export-ignore

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,3 +1,5 @@
+<!-- SPDX-License-Identifier: Apache-2.0 -->
+
 --- PR TEMPLATE INSTRUCTIONS (1) ---
 
 Looking to submit a Apache Hamilton Dataflow to the sf-hamilton-contrib module? If so go the the `Preview` tab and select the appropriate sub-template: