diff --git a/CHANGES.md b/CHANGES.md
index 89274fb..b07408c 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,12 @@
+# 0.12
+
+- use `current_span` when entering spans or sending messages
+- add `Trace.Ambient_span_provider.t` concept, to track the current span.
+    It is not part of the collector and is optional.
+- add `trace.thread-local-storage` optional library that implements the `Ambient_span_provider.t`
+- add a runtime events collector, + test, in `trace-runtime-events`
+- add `{thread,process}_sort_index` extension + TEF support
+
 # 0.11
 
 - entire rework of the collector, now lighter, and using an open sum type
diff --git a/dune-project b/dune-project
index 1850f8f..b66d80f 100644
--- a/dune-project
+++ b/dune-project
@@ -4,7 +4,7 @@
 
 (generate_opam_files true)
 
-(version 0.11)
+(version 0.12)
 
 (source
  (github ocaml-tracing/ocaml-trace))
@@ -98,9 +98,10 @@
   "A simple collector relying on runtime-events for OCaml 5. Some assembly required.")
  (depends
   (ocaml
-   (>= 5.0))
+   (>= 5.1))
   (trace
    (= :version))
+  (ppx_trace (and (= :version) :with-test))
   base-bigarray
   base-unix
   dune)
diff --git a/ppx_trace.opam b/ppx_trace.opam
index 10b4574..6e8602f 100644
--- a/ppx_trace.opam
+++ b/ppx_trace.opam
@@ -1,6 +1,6 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-version: "0.11"
+version: "0.12"
 synopsis: "A ppx-based preprocessor for trace"
 maintainer: ["Simon Cruanes"]
 authors: ["Simon Cruanes"]
diff --git a/src/core/ambient_span_provider.ml b/src/core/ambient_span_provider.ml
index 3f7c480..e9032ca 100644
--- a/src/core/ambient_span_provider.ml
+++ b/src/core/ambient_span_provider.ml
@@ -1,5 +1,5 @@
 (** Access/set the current span from some ambient context.
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 open Types
 
diff --git a/src/core/trace_core.mli b/src/core/trace_core.mli
index fd8215c..2be494b 100644
--- a/src/core/trace_core.mli
+++ b/src/core/trace_core.mli
@@ -184,7 +184,7 @@ val counter_float :
 val current_span : unit -> span option
 (** Access the current span from some ambient scope, {b if supported}. This is
     only supported if a {!Ambient_span_provider} has been set up.
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 val with_current_span_set_to : span -> (span -> 'a) -> 'a
 (** [with_current_span_set_to span f] sets the span as current span, enters
@@ -195,7 +195,7 @@ val with_current_span_set_to : span -> (span -> 'a) -> 'a
 
     Automatically called by {!with_span}.
 
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 (** {2 Collector} *)
 
@@ -230,7 +230,7 @@ val with_setup_collector : Collector.t -> (unit -> 'a) -> 'a
 val set_ambient_context_provider : Ambient_span_provider.t -> unit
 (** Install a provider for {!current_span} and {!with_current_span_set_to}. The
     default provider does nothing (ie [current_span ()] is always [None]).
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 (** {2 Extensions} *)
 
diff --git a/src/runtime-events/trace_runtime_events.mli b/src/runtime-events/trace_runtime_events.mli
index a57ea17..026a771 100644
--- a/src/runtime-events/trace_runtime_events.mli
+++ b/src/runtime-events/trace_runtime_events.mli
@@ -1,6 +1,6 @@
 (** Simple collector that emits trace events via Runtime_events.
 
-    @since NEXT_RELEASE *)
+    @since 0.12 *)
 
 (** {2 Event types for decoding} *)
 
diff --git a/trace-fuchsia.opam b/trace-fuchsia.opam
index 0dc6639..831c6bd 100644
--- a/trace-fuchsia.opam
+++ b/trace-fuchsia.opam
@@ -1,6 +1,6 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-version: "0.11"
+version: "0.12"
 synopsis:
   "A high-performance backend for trace, emitting a Fuchsia trace into a file"
 maintainer: ["Simon Cruanes"]
diff --git a/trace-runtime-events.opam b/trace-runtime-events.opam
index 9f09fd4..e16c1f4 100644
--- a/trace-runtime-events.opam
+++ b/trace-runtime-events.opam
@@ -1,6 +1,6 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-version: "0.11"
+version: "0.12"
 synopsis:
   "A simple collector relying on runtime-events for OCaml 5. Some assembly required."
 maintainer: ["Simon Cruanes"]
@@ -10,8 +10,9 @@ tags: ["trace" "tracing" "trace" "runtime-events"]
 homepage: "https://github.com/ocaml-tracing/ocaml-trace"
 bug-reports: "https://github.com/ocaml-tracing/ocaml-trace/issues"
 depends: [
-  "ocaml" {>= "5.0"}
+  "ocaml" {>= "5.1"}
   "trace" {= version}
+  "ppx_trace" {= version & with-test}
   "base-bigarray"
   "base-unix"
   "dune" {>= "2.9"}
diff --git a/trace-tef.opam b/trace-tef.opam
index 2f50695..9881892 100644
--- a/trace-tef.opam
+++ b/trace-tef.opam
@@ -1,6 +1,6 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-version: "0.11"
+version: "0.12"
 synopsis:
   "A simple backend for trace, emitting Catapult/TEF JSON into a file"
 maintainer: ["Simon Cruanes"]
diff --git a/trace.opam b/trace.opam
index f7922ed..3ee351a 100644
--- a/trace.opam
+++ b/trace.opam
@@ -1,6 +1,6 @@
 # This file is generated by dune, edit dune-project instead
 opam-version: "2.0"
-version: "0.11"
+version: "0.12"
 synopsis:
   "A lightweight stub for tracing/observability, agnostic in how data is collected"
 description: """