Add LangChain TinyFish integration

.github/AGENTS.md

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+# GitHub workflow guidance
+
+This directory contains maintainer-facing repository automation and notes.
+
+- Keep release-process documentation in `.github/README.md` or another maintainer-only repo doc, not in package `README.md` files that become PyPI project descriptions.
+- Python package publish workflows should read package name/version from the package `pyproject.toml`, check PyPI for that exact version, and skip publishing if it already exists.
+- Do not add automatic version bumping to publish workflows unless the release process is explicitly redesigned; package version bumps should be reviewed in PRs.
+- Use the repository `PYPI_API_TOKEN` Actions secret for token-based PyPI publishing. Never commit token values or package credentials.
+- Keep publish workflows scoped by `paths` to the package directory and the workflow file so unrelated merges do not trigger package release jobs.

.github/README.md

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+# Maintainer notes
+
+This file is for repository maintainers. Do not copy release-process notes into an integration package `README.md`: package READMEs are used as PyPI project descriptions.
+
+## Python integration releases
+
+Python integration publish workflows do not bump package versions automatically. Each workflow reads the package name and version from that integration's `pyproject.toml`, checks PyPI for that exact version, and publishes only when the version does not already exist.
+
+To publish a new version:
+
+1. Update the package version in the relevant `pyproject.toml`.
+2. Commit the version bump with the code change.
+3. Merge to `main`.
+4. Let the push-to-`main` publish workflow run.
+
+Current Python package version files:
+
+| Integration | Package | Version file |
+| --- | --- | --- |
+| Google ADK | `tinyfish-adk` | `google-adk/pyproject.toml` |
+| CrewAI | `tinyfish-web-agent` | `crew-ai/pyproject.toml` |
+| LangChain | `langchain-tinyfish` | `langchain/pyproject.toml` |
+
+PyPI versions are immutable. If a version has already been published, bump to a new version such as a patch release before merging.
+
+The publish workflows use the repository `PYPI_API_TOKEN` Actions secret provisioned through `github-control`; never commit token values or package credentials.

.github/workflows/langchain-ci.yml

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+name: LangChain CI
+
+on:
+  pull_request:
+    branches: [main]
+    paths:
+      - ".github/workflows/langchain-ci.yml"
+      - "langchain/**"
+  push:
+    branches: [main]
+    paths:
+      - ".github/workflows/langchain-ci.yml"
+      - "langchain/**"
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    defaults:
+      run:
+        working-directory: langchain
+
+    steps:
+      - uses: actions/checkout@v6
+
+      - uses: actions/setup-python@v6
+        with:
+          python-version: "3.12"
+
+      - run: python -m pip install --upgrade pip
+
+      - run: python -m pip install -e . -r requirements-dev.txt
+
+      - run: make lint
+
+      - run: make test
+
+      - run: python -m build

.github/workflows/langchain-publish.yml

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+name: LangChain CD - Publish to PyPI
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - ".github/workflows/langchain-publish.yml"
+      - "langchain/**"
+
+jobs:
+  build:
+    name: Build distribution
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    outputs:
+      version-exists: ${{ steps.version.outputs.exists }}
+      package-version: ${{ steps.version.outputs.version }}
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
+      - name: Set up Python
+        uses: actions/setup-python@v6
+        with:
+          python-version: "3.12"
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v8.1.0
+
+      - name: Check PyPI version availability
+        id: version
+        working-directory: ./langchain
+        run: |
+          PACKAGE=$(python -c "import tomllib; f=open('pyproject.toml','rb'); d=tomllib.load(f); print(d['project']['name'])")
+          VERSION=$(python -c "import tomllib; f=open('pyproject.toml','rb'); d=tomllib.load(f); print(d['project']['version'])")
+          echo "package=${PACKAGE}" >> "$GITHUB_OUTPUT"
+          echo "version=${VERSION}" >> "$GITHUB_OUTPUT"
+          RESULT=$(python - "$PACKAGE" "$VERSION" <<'PY'
+          import sys
+          import urllib.error
+          import urllib.parse
+          import urllib.request
+
+          package = sys.argv[1]
+          version = sys.argv[2]
+          url = f"https://pypi.org/pypi/{urllib.parse.quote(package)}/{version}/json"
+          try:
+              with urllib.request.urlopen(url, timeout=10):
+                  pass
+          except urllib.error.HTTPError as exc:
+              if exc.code == 404:
+                  print("missing")
+                  sys.exit(0)
+              print(f"PyPI returned HTTP {exc.code} while checking {url}", file=sys.stderr)
+              sys.exit(2)
+          except Exception as exc:
+              print(f"Failed to check PyPI for {url}: {exc}", file=sys.stderr)
+              sys.exit(2)
+          print("exists")
+          PY
+          )
+          case "$RESULT" in
+            exists)
+              echo "exists=true" >> "$GITHUB_OUTPUT"
+              echo "${PACKAGE} ${VERSION} already exists on PyPI; skipping publish."
+              ;;
+            missing)
+              echo "exists=false" >> "$GITHUB_OUTPUT"
+              echo "${PACKAGE} ${VERSION} is available on PyPI; building distribution."
+              ;;
+            *)
+              echo "Unexpected PyPI availability result: $RESULT"
+              exit 1
+              ;;
+          esac
+
+      - name: Build package
+        if: steps.version.outputs.exists == 'false'
+        working-directory: ./langchain
+        run: uv build
+
+      - name: Upload distribution artifact
+        if: steps.version.outputs.exists == 'false'
+        uses: actions/upload-artifact@v7
+        with:
+          name: python-package-distributions
+          path: langchain/dist/
+
+  publish-pypi:
+    name: Publish to PyPI
+    needs: build
+    if: needs.build.outputs.version-exists == 'false'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Download distributions
+        uses: actions/download-artifact@v8
+        with:
+          name: python-package-distributions
+          path: dist/
+
+      - name: Publish to PyPI
+        uses: pypa/gh-action-pypi-publish@release/v1
+        with:
+          packages-dir: dist/
+          password: ${{ secrets.PYPI_API_TOKEN }}

langchain/.gitignore

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+*.egg-info/
+*.egg
+dist/
+build/
+__pycache__/
+*.pyc
+*.pyo
+.env
+.claude/
+.mypy_cache/
+.ruff_cache/
+.pytest_cache/

langchain/LICENSE

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+MIT License
+
+Copyright (c) 2026 TinyFish
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

langchain/Makefile

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+.PHONY: all format lint test integration_test check_imports clean
+
+all: format lint test
+
+TEST_FILE ?= tests/unit_tests/
+integration_test: TEST_FILE = tests/integration_tests/
+
+format:
+	ruff format langchain_tinyfish tests
+	ruff check --fix langchain_tinyfish tests
+
+lint:
+	ruff check langchain_tinyfish tests
+	mypy langchain_tinyfish
+
+test integration_test:
+	pytest $(TEST_FILE) -v
+
+check_imports: $(shell find langchain_tinyfish -name '*.py')
+	python scripts/check_imports.py $^
+
+clean:
+	rm -rf build dist *.egg-info .pytest_cache .mypy_cache .ruff_cache
+	find . -type d -name __pycache__ -exec rm -rf {} +