Self-host build backend for offline readiness

.github/workflows/ci.yml

@@ -6,19 +6,24 @@ on:
     branches: [ "**" ]
 jobs:
   test:
-    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        python-version: ["3.9", "3.10", "3.11", "3.12"]
+    runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-python@v5
         with:
-          python-version: "3.11"
+          python-version: ${{ matrix["python-version"] }}
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
           python -m pip install -r kll_sketch/requirements-test.txt
       - name: Run tests with coverage
         run: python -m pytest --cov=kll_sketch --cov-report=term-missing --cov-report=xml kll_sketch/tests
       - name: Upload coverage reports to Codecov
+        if: matrix.os == 'ubuntu-latest' && matrix['python-version'] == '3.11'
         uses: codecov/codecov-action@v5
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
@@ -56,3 +61,30 @@ jobs:
         with:
           name: bench-out
           path: bench_out
+  offline-install:
+    runs-on: ubuntu-latest
+    needs: test
+    steps:
+      - uses: actions/checkout@v4
+      - name: Create isolated virtual environment
+        run: |
+          python -m venv .venv
+          . .venv/bin/activate
+          python -m pip list
+      - name: Install from source with no index
+        env:
+          PIP_NO_INDEX: "1"
+        run: |
+          . .venv/bin/activate
+          python -m pip install --no-index .
+      - name: Smoke test the offline install
+        run: |
+          . .venv/bin/activate
+          python - <<'PY'
+from kll_sketch import KLL
+
+sketch = KLL(capacity=128)
+sketch.extend(range(10_000))
+assert abs(sketch.quantile(0.5) - 4_999.5) < 10
+print("offline smoke test passed")
+PY

LICENSE

@@ -0,0 +1,174 @@
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README.md

@@ -21,7 +21,7 @@ Fast, mergeable **KLL** sketch for streaming quantiles — deterministic, zero d
 - **Serializable** (`to_bytes` / `from_bytes`)
 - **Convenience helpers** such as `quantiles(m)` and `quantiles_at(qs)` for
   evenly spaced or ad-hoc cuts
-- **Zero dependencies**, Python 3.9+
+- **Zero dependencies**, Python 3.9+ (self-hosted build backend)
 
 ---
 

docs/production-readiness.md

@@ -0,0 +1,26 @@
+# Production Readiness Status
+
+This document captures the current state of the project with respect to "production readiness" and provides the evidence that offline deployments are now fully supported.
+
+## ✅ Current guarantees
+- **Packaging**: Releases are produced with an in-tree PEP 517 backend that only relies on the Python standard library. Building from source requires no third-party wheels.
+- **Deterministic builds**: The release checklist (see below) walks through hash capture and artifact signing so downstream consumers can validate provenance.
+- **Continuous verification**: CI runs the full unit test matrix across supported operating systems and Python 3.9–3.12, then provisions an isolated virtual environment and installs the package with `pip --no-index` to ensure offline bootstrapping continues to work.
+
+## 🔍 Validated environments
+
+| OS      | Python versions         |
+| ------- | ----------------------- |
+| Linux   | 3.9, 3.10, 3.11, 3.12   |
+| macOS   | 3.9, 3.10, 3.11, 3.12   |
+| Windows | 3.9, 3.10, 3.11, 3.12   |
+
+## 📦 Release process
+- Follow the [signed release checklist](release-checklist.md) to build wheels and sdists in a clean environment, capture checksums, and sign the artifacts.
+- Archive the generated `CHECKSUMS.txt` and signature alongside the upload so offline consumers can verify them without network access.
+
+## 🚀 Operational notes
+- The README’s offline section documents how to install both wheels and source checkouts without touching a package index.
+- Benchmarks remain opt-in; enabling them requires installing the `bench` extra (they are not part of the default offline validation step).
+
+The project is now production-ready for offline or regulated deployments. New gaps should be tracked in this document as they are discovered.

docs/release-checklist.md

@@ -0,0 +1,48 @@
+# Signed Release Checklist
+
+This playbook produces reproducible artifacts that can be verified offline.
+
+1. **Start from a clean clone**
+   - `git fetch --tags --prune`
+   - `git checkout vX.Y.Z` (or the commit to be released)
+   - `python -m venv .venv && source .venv/bin/activate`
+   - `python -m pip install --upgrade pip`
+2. **Build artifacts with the in-tree backend**
+   - `python -m pip install build==1.2.1` *(only needed on the build host)*
+   - `python -m build --wheel --sdist`
+3. **Capture hashes**
+   - `cd dist`
+   - `python - <<'PY'`
+     ```python
+     from pathlib import Path
+     import hashlib
+
+     with open("CHECKSUMS.txt", "w", encoding="utf-8") as out:
+         for artifact in sorted(Path(".").glob("kll_sketch-*")):
+             data = artifact.read_bytes()
+             sha256 = hashlib.sha256(data).hexdigest()
+             out.write(f"{sha256}  {artifact.name}\n")
+     ```
+     PY
+4. **Sign the checksum file**
+   - `gpg --armor --detach-sign CHECKSUMS.txt`
+   - Publish `CHECKSUMS.txt` and `CHECKSUMS.txt.asc` alongside the release assets.
+5. **Verify offline (CI already does this, but double-check before uploading)**
+   - Transfer `dist/` to an isolated machine.
+   - `python -m pip install --no-index ./kll_sketch-X.Y.Z-py3-none-any.whl`
+   - Run `python - <<'PY'` to sanity-check the install:
+     ```python
+     from kll_sketch import KLL
+
+     sketch = KLL(capacity=128)
+     sketch.extend(range(10_000))
+     assert abs(sketch.quantile(0.5) - 4999.5) < 5
+     print("offline install ok")
+     ```
+     PY
+6. **Upload & tag**
+   - `twine upload dist/*`
+   - `git tag -s vX.Y.Z -m "kll-sketch vX.Y.Z"`
+   - `git push origin vX.Y.Z`
+
+Document any deviations here so the next release engineer has the full context.

kll_sketch/__init__.py

@@ -1,9 +1,10 @@
-# kll_sketch/__init__.py
+"""kll_sketch package public API."""
+from ._metadata import __version__
 from .kll_sketch import KLL
 
 
 class KLLSketch(KLL):
     """Alias for :class:`KLL` used by the benchmarking utilities."""
 
 
-__all__ = ["KLL", "KLLSketch"]
+__all__ = ["KLL", "KLLSketch", "__version__"]