drop Python 3.9 support, fix mutmut CLI, align lint to min version

Author: nikolay-e

.github/workflows/ci.yml

@@ -51,18 +51,18 @@ jobs:
       - name: Checkout Code
         uses: actions/checkout@v6
 
-      - name: Set up Python 3.11
+      - name: Set up Python 3.10
         uses: actions/setup-python@v6
         with:
-          python-version: '3.11'
+          python-version: '3.10'
 
       - name: Cache pip Dependencies
         uses: actions/cache@v5
         with:
           path: ~/.cache/pip
-          key: ${{ runner.os }}-lint-pip-3.11-${{ hashFiles('**/pyproject.toml') }}
+          key: ${{ runner.os }}-lint-pip-3.10-${{ hashFiles('**/pyproject.toml') }}
           restore-keys: |
-            ${{ runner.os }}-lint-pip-3.11-
+            ${{ runner.os }}-lint-pip-3.10-
 
       - name: Install Linters and Type Checker
         run: |
@@ -87,7 +87,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python-version: [3.9, '3.10', '3.11', '3.12', '3.13']
+        python-version: ['3.10', '3.11', '3.12', '3.13']
 
     runs-on: ${{ matrix.os }}
 
@@ -153,7 +153,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [pypy-3.9, pypy-3.10]
+        python-version: [pypy-3.10, pypy-3.11]
 
     steps:
       - name: Checkout Code
@@ -208,7 +208,7 @@ jobs:
 
       - name: Run mutation testing
         run: |
-          mutmut run --paths-to-mutate=src/treemapper/ --tests-dir=tests/ || true
+          mutmut run || true
           mutmut results || true
 
   # ============================================================================
@@ -332,7 +332,7 @@ jobs:
           sonar.tests=tests
           sonar.python.coverage.reportPaths=coverage.xml
           sonar.python.xunit.reportPath=test-results.xml
-          sonar.python.version=3.9,3.10,3.11,3.12,3.13
+          sonar.python.version=3.10,3.11,3.12,3.13
           EOF
 
       - name: SonarCloud Scan

pyproject.toml

@@ -13,14 +13,14 @@ line_length = 130
 
 [tool.ruff]
 line-length = 130
-target-version = "py39"
+target-version = "py310"
 
 [tool.ruff.lint]
 select = ["E", "F", "W", "I", "N", "UP", "RUF"]
 ignore = ["E501"]  # Line length handled by black
 
 [tool.mypy]
-python_version = "3.9"
+python_version = "3.10"
 strict = true
 warn_return_any = true
 warn_unused_configs = true
@@ -69,15 +69,14 @@ authors = [
 ]
 description = "Export codebase structure and contents for AI/LLM context"
 readme = "README.md"
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 license = { file = "LICENSE" }
 keywords = ["code-analysis", "directory-tree", "yaml", "json", "llm", "ai", "codebase", "context", "chatgpt", "claude", "code-context", "export", "tree", "gpt-context", "llm-context", "code-to-prompt", "claude-context"]
 classifiers = [
     "Development Status :: 5 - Production/Stable",
     "Environment :: Console",
     "Intended Audience :: Developers",
     "Programming Language :: Python :: 3",
-    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",

tests/utils.py

@@ -1,7 +1,7 @@
 # tests/utils.py
 from collections.abc import Hashable
 from pathlib import Path
-from typing import Any, Optional
+from typing import Any
 
 import pytest
 import yaml
@@ -35,7 +35,7 @@ def get_all_files_in_tree(node: dict[str, Any]) -> set[str]:
     return names
 
 
-def find_node_by_path(tree: dict[str, Any], path_segments: list[str]) -> Optional[dict[str, Any]]:
+def find_node_by_path(tree: dict[str, Any], path_segments: list[str]) -> dict[str, Any] | None:
     """Find a node in the tree by list of path segments relative to root node."""
     current_node = tree
     for segment in path_segments: