diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index b3b907c..3309acd 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -65,7 +65,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
+        python-version: ["3.11", "3.12", "3.13", "3.14"]
 
     steps:
       - name: Checkout repository
diff --git a/AGENTS.md b/AGENTS.md
index da9b34c..3fe40d4 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -41,7 +41,7 @@ Do not tell the user you are "done" or that changes are "complete" until all thr
 - Use ruff for formatting and linting
 - Configuration is in `pyproject.toml` under `[tool.ruff]`
 - Line length: 100 characters
-- Target Python version: 3.9+
+- Target Python version: 3.11+
 
 ---
 
diff --git a/docs/index.md b/docs/index.md
index 89c1654..92309d8 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -10,7 +10,7 @@ classes whose constructor arguments describe their state.
 python -m pip install serializable
 ```
 
-Python 3.9 or later is required.
+Python 3.11 or later is required.
 
 ## Save and reload an object
 
diff --git a/pyproject.toml b/pyproject.toml
index 0afcfd6..782479d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -18,15 +18,13 @@ classifiers = [
     "License :: OSI Approved :: Apache Software License",
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
-    "Programming Language :: Python :: 3.9",
-    "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
     "Programming Language :: Python :: 3.14",
     "Typing :: Typed",
 ]
-requires-python = ">=3.9"
+requires-python = ">=3.11"
 dependencies = [
     "typechecks>=0.0.2",
 ]
@@ -55,7 +53,7 @@ include = ["serializable*"]
 serializable = ["py.typed"]
 
 [tool.ruff]
-target-version = "py39"
+target-version = "py311"
 line-length = 100
 src = ["serializable", "tests"]
 exclude = [
@@ -85,8 +83,8 @@ ignore = [
     "B008",   # do not perform function calls in argument defaults
     "B905",   # zip() without explicit strict
     "SIM108", # use ternary operator instead of if-else
-    "UP007",  # use X | Y for type unions (need Python 3.10+)
-    "UP045",  # use X | None for Optional (need Python 3.10+)
+    "UP007",  # retain the established Union annotation style
+    "UP045",  # retain the established Optional annotation style
 ]
 
 [tool.ruff.lint.per-file-ignores]
@@ -103,9 +101,7 @@ ignore = [
 known-first-party = ["serializable"]
 
 [tool.mypy]
-# Annotations are never evaluated at runtime (`from __future__ import annotations`),
-# so checking them as 3.10 also covers 3.9, which mypy 2 can no longer target.
-python_version = "3.10"
+python_version = "3.11"
 
 [tool.pytest.ini_options]
 testpaths = ["tests"]
diff --git a/serializable/version.py b/serializable/version.py
index 156ccc6..ce2b93e 100644
--- a/serializable/version.py
+++ b/serializable/version.py
@@ -1,4 +1,4 @@
-__version__ = "1.3.1"
+__version__ = "1.3.2"
 
 
 def print_version():
diff --git a/tasks/todo.md b/tasks/todo.md
new file mode 100644
index 0000000..220e48c
--- /dev/null
+++ b/tasks/todo.md
@@ -0,0 +1,26 @@
+# Python 3.11 support floor (#24)
+
+## Specification
+
+Require Python 3.11 or newer without adding an upper bound. Advertise the
+tested 3.11–3.14 range, remove 3.9/3.10 from CI, and align Ruff and mypy's
+language targets. Keep runtime serialization behavior and dependencies as they
+are. Bump the patch version for the release.
+
+## Plan
+
+- [x] Read issue, packaging, CI, repository guidance, and existing tests.
+- [x] Check plan before implementation: this is a metadata/tooling policy change;
+  the current test matrix already covers all four retained versions.
+- [x] Update metadata, CI, type-check targets, and version.
+- [x] Run `./format.sh`, `./lint.sh`, and `./test.sh` in an isolated environment.
+- [x] Verify installation metadata and dependency resolution on Python 3.11 and
+  3.14; review the diff.
+- [ ] Open PR, pass CI, merge, deploy from clean master, and verify publication.
+
+## Review
+
+`./format.sh` left all 21 source/test files unchanged. `./lint.sh` passed
+Ruff, formatter, and mypy checks. `./test.sh` passed all 100 tests on both
+Python 3.11.12 and 3.14.6. Isolated dependency checks passed at both endpoints;
+installed metadata reports version 1.3.2 and `Requires-Python: >=3.11`.