Add type annotations to code-base (automatically via Claude; and then tweaked and validated hand).

[matthewwardrop]

This gives rich type annotations validated by mypy. We fixed a few small bugs along the way.

[Copilot]

Pull request overview

This PR introduces project-wide Python type annotations and enforces them via a new mypy configuration, with a few incidental runtime-safety tweaks made while tightening types.

Changes:

• Add typing_extensions and a mypy-based type-checking step/configuration in pyproject.toml.
• Add/upgrade type annotations across core modules (ducts, registries, caches, utils, filesystem/remote/database clients).
• Apply a handful of small behavioral fixes discovered during typing (e.g., safer module detection in logging, stricter config save/load validation).

Reviewed changes

Copilot reviewed 45 out of 46 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
pyproject.toml	Adds typing_extensions, lint env type-checking deps, mypy config, and runs mypy in lint checks.
.gitignore	Ignores .mypy_cache/.
omniduct/__init__.py	Adds return type for about().
omniduct/_version.py	Switches dependency lists to be derived from distribution metadata.
omniduct/duct.py	Adds extensive typing (incl. Self) and some narrowing/casts.
omniduct/registry.py	Types for registry construction/lookup and namespace population helpers.
omniduct/restful/base.py	Adds typing for REST client base and request helpers.
omniduct/utils/about.py	Adds typing + clarifies notebook/text rendering control flow.
omniduct/utils/config.py	Adds typing, improves module detection, and validates save/load filename presence.
omniduct/utils/debug.py	Adds typing and hardens logger context inference and progress bar finishing.
omniduct/utils/decorators.py	Adds typing for decorator helpers.
omniduct/utils/dependencies.py	Types + simplifies package version detection via importlib.metadata.
omniduct/utils/magics.py	Adds typing for IPython magic argument wrappers/providers.
omniduct/utils/ports.py	Adds typing and a small regex-match guard in load balancer.
omniduct/utils/processes.py	Adds typing to subprocess helpers and timeout context manager.
omniduct/utils/proxies.py	Adds typing to TreeProxy helpers and methods.
omniduct/utils/storage.py	Adds typing to ensure_path_exists.
omniduct/utils/submodules.py	Adds typing + improves docstring format for submodule import helper.
omniduct/remotes/base.py	Adds typing across port-forward registry and remote base APIs.
omniduct/remotes/ssh.py	Adds typing across SSH remote implementation.
omniduct/remotes/ssh_paramiko.py	Adds typing across Paramiko SSH remote implementation.
omniduct/remotes/stub.py	Adds typing to remote stub methods.
omniduct/filesystems/_pyarrow_compat.py	Adds typing to PyArrow compatibility filesystem wrapper.
omniduct/filesystems/_webhdfs_helpers.py	Adds typing for WebHDFS helpers and XML parsing casts.
omniduct/filesystems/local.py	Adds typing to local filesystem implementation.
omniduct/filesystems/s3.py	Adds typing to S3 filesystem implementation.
omniduct/filesystems/stub.py	Adds typing to filesystem stub methods.
omniduct/filesystems/webhdfs.py	Adds typing and narrows remote/filesystem assumptions for auto-conf.
omniduct/caches/_serializers.py	Adds typing to serializers and file handles.
omniduct/caches/base.py	Adds typing for cache API + cached_method decorator.
omniduct/caches/filesystem.py	Adds typing and clarifies filesystem-client resolution via registry.
omniduct/databases/_cursor_formatters.py	Adds typing across cursor formatters and CSV formatting.
omniduct/databases/_cursor_serializer.py	Adds typing for cursor serializer and cached cursor wrapper.
omniduct/databases/_namespaces.py	Adds typing to namespace parsing/rendering.
omniduct/databases/_pandas.py	Adds typing and guards for pandas internal SQL helpers in multi-insert mode.
omniduct/databases/_schemas.py	Adds typing + refactors reflected table binding for pandas introspection.
omniduct/databases/druid.py	Adds typing for Druid client.
omniduct/databases/exasol.py	Adds typing for Exasol client.
omniduct/databases/hiveserver2.py	Adds typing + a few runtime checks for hive CLI path.
omniduct/databases/neo4j.py	Adds typing for Neo4j client.
omniduct/databases/presto.py	Adds typing + hardens error parsing branch.
omniduct/databases/pyspark.py	Adds typing for PySpark client + SparkCursor wrapper.
omniduct/databases/sqlalchemy.py	Adds typing for SQLAlchemy client, dataframe/table operations.
omniduct/databases/stub.py	Adds typing for database stub methods.

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