diff --git a/AGENTS.md b/AGENTS.md
index 09d0564f28a..8e3de8d5c58 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -73,6 +73,15 @@ make format
 uv run --group lint mypy .
 ```
 
+#### Environment and dependency management
+
+Use `uv` for all environment and dependency operations in this monorepo. Do not invoke `pip`, `poetry`, or `conda` directly.
+
+- Let `uv` manage the interpreter and virtual environments — `uv sync` and `uv run` operate without manual `source .venv/bin/activate`. Do not create ad-hoc virtual environments outside the package directory.
+- Each package targets its own supported Python range via its `pyproject.toml`; do not pin a global Python version. If you need an interpreter explicitly, defer to the package's `requires-python` rather than assuming system Python.
+- Install dependencies explicitly through `uv sync` (optionally `--group <name>` / `--all-groups`); never let them install implicitly.
+- Don't mix environments within a session, and don't add new dependencies unless strictly required — when you do, justify them (recent releases/commits, adoption).
+
 #### Key config files
 
 - pyproject.toml: Main workspace configuration with dependency groups
diff --git a/CLAUDE.md b/CLAUDE.md
index 09d0564f28a..8e3de8d5c58 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -73,6 +73,15 @@ make format
 uv run --group lint mypy .
 ```
 
+#### Environment and dependency management
+
+Use `uv` for all environment and dependency operations in this monorepo. Do not invoke `pip`, `poetry`, or `conda` directly.
+
+- Let `uv` manage the interpreter and virtual environments — `uv sync` and `uv run` operate without manual `source .venv/bin/activate`. Do not create ad-hoc virtual environments outside the package directory.
+- Each package targets its own supported Python range via its `pyproject.toml`; do not pin a global Python version. If you need an interpreter explicitly, defer to the package's `requires-python` rather than assuming system Python.
+- Install dependencies explicitly through `uv sync` (optionally `--group <name>` / `--all-groups`); never let them install implicitly.
+- Don't mix environments within a session, and don't add new dependencies unless strictly required — when you do, justify them (recent releases/commits, adoption).
+
 #### Key config files
 
 - pyproject.toml: Main workspace configuration with dependency groups