diff --git a/specification/configuration/api.md b/specification/configuration/api.md
index ceb5cacfddd..806e278cd55 100644
--- a/specification/configuration/api.md
+++ b/specification/configuration/api.md
@@ -13,6 +13,7 @@ weight: 1
   * [ConfigProvider](#configprovider)
     + [ConfigProvider operations](#configprovider-operations)
       - [Get instrumentation config](#get-instrumentation-config)
+      - [Add config change listener](#add-config-change-listener)
   * [ConfigProperties](#configproperties)
 
 <!-- tocstop -->
@@ -49,6 +50,7 @@ default `ConfigProvider`, and set/register it.
 The `ConfigProvider` MUST provide the following functions:
 
 * [Get instrumentation config](#get-instrumentation-config)
+* [Add config change listener](#add-config-change-listener)
 
 TODO: decide if additional operations are needed to improve API ergonomics
 
@@ -63,6 +65,64 @@ configuration mapping node.
 If the `.instrumentation` node is not set, get instrumentation config SHOULD
 return an empty `ConfigProperties` (as if `.instrumentation: {}` was set).
 
+##### Add config change listener
+
+Register a listener to be notified when configuration at a specific watched path
+changes.
+
+This API MUST accept the following parameters:
+
+* `path`: declarative configuration path to watch.
+* `listener`: callback invoked on changes.
+
+**Returns:** A registration handle with a close operation.
+
+Path requirements:
+
+* `path` MUST be an absolute declarative configuration path.
+* `path` matching is exact. Wildcards and prefix matching are not supported.
+* In this version, paths are defined only for named properties. Sequence/array indexing is not supported
+* API implementations SHOULD document accepted path syntax in language-specific
+  docs and include examples such as `.instrumentation/development.general.http`
+  and `.instrumentation/development.java.methods`.
+
+Callback requirements:
+
+* If a watched path changes, the callback MUST receive:
+  * `path`: the changed watched path.
+  * `newConfig`: the updated [`ConfigProperties`](#configproperties) for that
+    path.
+* `newConfig` MUST be a valid [`ConfigProperties`](#configproperties) instance
+  (never null/nil/None).
+* If the watched node is unset or cleared, `newConfig` MUST represent an empty
+  mapping node (equivalent to `{}`).
+* Implementations MAY coalesce rapid successive updates for the same watched
+  path. If coalescing is performed, callback delivery MUST use the latest
+  configuration state.
+* Ordering of callback delivery is not specified, including for updates touching
+  multiple watched paths in one configuration transaction.
+
+Concurrency and lifecycle requirements:
+
+* Callback implementations SHOULD be reentrant and SHOULD avoid blocking
+  operations.
+* Implementations MUST document callback concurrency guarantees. If they do not,
+  users MUST assume callbacks may be invoked concurrently.
+* Closing a registration handle MUST unregister the listener.
+* Close MUST be idempotent (subsequent calls have no effect).
+* After close returns, implementations SHOULD stop new callback delivery for that
+  registration. A callback already in progress MAY complete.
+* Registrations SHOULD be dropped automatically when the corresponding
+  `ConfigProvider` is shut down or otherwise disposed.
+
+Error handling and unsupported providers:
+
+* If callback execution throws an error, implementations SHOULD isolate the
+  failure to that callback and SHOULD continue notifying other callbacks.
+* If a provider does not support change notifications, registration MUST still
+  succeed by returning a no-op registration handle, and callbacks MUST NOT be
+  invoked.
+
 ### ConfigProperties
 
 `ConfigProperties` is a programmatic representation of a configuration mapping