diff --git a/requirements-dev.txt b/requirements-dev.txt
index 697d674..77948ef 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -1,7 +1,4 @@
-# Development/test dependencies (mirrors [project.optional-dependencies].dev
-# in pyproject.toml).
--r requirements.txt
-pytest>=7.4
-ruff>=0.6
-mypy>=1.11
-types-requests
+# Development install. Editable package plus the [dev] extra (pytest, ruff,
+# mypy, ...). pyproject.toml remains the single source of truth; there is no
+# manual dependency mirror to keep in sync.
+-e .[dev]
diff --git a/requirements.txt b/requirements.txt
index b3cd6be..e361a6e 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-# Runtime dependencies (mirrors [project.dependencies] in pyproject.toml).
-# Provided for users who want to verify/install dependencies without pip's
-# PEP 517 build isolation, e.g. `pip install -r requirements.txt`.
-requests>=2.31,<3
+# Runtime install. pyproject.toml is the single source of truth for
+# dependencies; this file just installs the package (and thus its declared
+# runtime dependencies) so `pip install -r requirements.txt` keeps working.
+.