diff --git a/CHANGES.md b/CHANGES.md
index f7a9a6e..a4ce4b5 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -2,7 +2,12 @@
  
 ## 5.4.0 (unreleased)
 
-<!-- Add future changes here -->
+- Fix: A hook namespace no longer swallows packages whose name merely starts with it.
+  Section ownership now requires an exact `[namespace]` match or a `[namespace:subsection]`
+  prefix (the `:` separator cannot occur in a package name), so a hook like `uv` no longer
+  silently drops packages such as `uvst.addon`. Hook config sections previously written as
+  `[namespace-section]` must be renamed to `[namespace:section]`.
+  [jensens]
 
 
 ## 5.3.0 (2026-05-29)
diff --git a/EXTENDING.md b/EXTENDING.md
index 2363a96..d251da6 100644
--- a/EXTENDING.md
+++ b/EXTENDING.md
@@ -11,13 +11,19 @@ To avoid naming conflicts, all hook-related settings and config sections must be
 
 It is recommended to use the package name containing the hook as a namespace.
 
+Settings keys in `[settings]` and package sections are namespaced with a `namespace-` prefix.
+Dedicated hook config sections are named either exactly `[namespace]` or `[namespace:subsection]`.
+The `:` separator is used on purpose: it cannot occur in a package name, so a hook namespace
+can never accidentally claim a package section whose name merely starts with the same letters
+(e.g. a `uv` hook must not swallow a package named `uvst.addon`).
+
 This looks like so:
 
 ```INI
 [settings]
 myextension-global_setting = 1
 
-[myextension-section]
+[myextension:section]
 setting = value
 
 [foo.bar]
@@ -49,7 +55,7 @@ class MyExtension(Hook):
 
         # Example: Access hook-specific sections
         for section_name, section_config in state.configuration.hooks.items():
-            if section_name.startswith('myextension-'):
+            if section_name == 'myextension' or section_name.startswith('myextension:'):
                 # Process your hook's configuration
                 pass
 
@@ -100,7 +106,7 @@ Replace:
 
 - Use your package name as namespace prefix
 - All settings: `namespace-setting_name`
-- All sections: `[namespace-section]`
+- All sections: `[namespace]` or `[namespace:section]` (the `:` separator cannot occur in a package name, so it prevents collisions with package sections)
 - This prevents conflicts with other hooks
 
 ## Example Use Cases
diff --git a/src/mxdev/config.py b/src/mxdev/config.py
index 2dea2e0..61ec767 100644
--- a/src/mxdev/config.py
+++ b/src/mxdev/config.py
@@ -109,8 +109,14 @@ def __init__(
                 self.ignore_keys.append(line)
 
         def is_ns_member(name) -> bool:
+            # A section belongs to a hook only when its name is exactly the
+            # hook namespace or is prefixed with "<namespace>:". The colon
+            # cannot occur in a package name, so it unambiguously separates
+            # hook sections from package sections and avoids swallowing
+            # packages that merely start with the namespace (e.g. a "uv" hook
+            # must not claim a package named "uvst.addon").
             for hook in hooks:
-                if name.startswith(hook.namespace):
+                if name == hook.namespace or name.startswith(f"{hook.namespace}:"):
                     return True
             return False
 
diff --git a/tests/test_config.py b/tests/test_config.py
index 3fb37b4..b7a48e0 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -311,3 +311,66 @@ def test_config_parse_multiple_pushurls(tmp_path):
     # package2 should have single pushurl (no pushurls list)
     assert "pushurls" not in config.packages["package2"]
     assert config.packages["package2"]["pushurl"] == "git@github.com:test/repo2.git"
+
+
+def test_package_name_starting_with_hook_namespace_is_not_swallowed(tmp_path):
+    """A package whose name merely starts with a hook namespace stays a package.
+
+    Regression: with the ``uv`` hook (namespace ``"uv"``) registered, packages
+    like ``uvst.addon`` were silently classified as hook sections and dropped
+    from ``config.packages`` because section ownership used an unanchored
+    ``str.startswith`` match.
+    """
+    from mxdev.config import Configuration
+    from mxdev.hooks import Hook
+
+    class UvHook(Hook):
+        namespace = "uv"
+
+    config_content = """
+[settings]
+requirements-in = requirements.txt
+
+[uvst.addon]
+url = https://github.com/example/uvst.addon.git
+"""
+    config_file = tmp_path / "mx.ini"
+    config_file.write_text(config_content)
+
+    config = Configuration(str(config_file), hooks=[UvHook()])
+
+    assert "uvst.addon" in config.packages
+    assert "uvst.addon" not in config.hooks
+
+
+def test_hook_section_with_namespace_delimiter_belongs_to_hook(tmp_path):
+    """Sections named exactly ``<namespace>`` or prefixed ``<namespace>:`` are hook sections.
+
+    A colon cannot occur in a package name, so it is the unambiguous delimiter
+    separating hook sections from package sections.
+    """
+    from mxdev.config import Configuration
+    from mxdev.hooks import Hook
+
+    class UvHook(Hook):
+        namespace = "uv"
+
+    config_content = """
+[settings]
+requirements-in = requirements.txt
+
+[uv]
+some-setting = value
+
+[uv:sources]
+another = thing
+"""
+    config_file = tmp_path / "mx.ini"
+    config_file.write_text(config_content)
+
+    config = Configuration(str(config_file), hooks=[UvHook()])
+
+    assert "uv" in config.hooks
+    assert "uv:sources" in config.hooks
+    assert "uv" not in config.packages
+    assert "uv:sources" not in config.packages