diff --git a/AUDIT.md b/AUDIT.md
index a257077..ebd9197 100644
--- a/AUDIT.md
+++ b/AUDIT.md
@@ -2,6 +2,12 @@
 
 Per `CLAUDE.md`: this file records material changes to the repo (server, admin, client). For a client package, that means public API, on-the-wire request shape, and protocol-conformance posture.
 
+## 2026-07-27 — runcycles floor raised to 0.5.0
+
+**Scope:** dependency floor only; no wire-shape, public API, or exception-contract change
+
+`pyproject.toml` raises the `runcycles` floor from `>=0.4.1` to `>=0.5.0` (durable commit retries: on-disk journal with replay, `POST /v1/events` fallback for expired commits, 429/auth handling that never releases spent budget). The guard's direct `commit_reservation` calls do not engage the SDK's new retry engine, so the documented `AP2GuardCommitUncertain` / `AP2GuardCommitFailed` semantics are unchanged; engine adoption is a candidate follow-up that would shift transient commit failures from "uncertain, caller reconciles" to "journaled, will settle". Full suite against `runcycles==0.5.0`: 148 tests passed, 99.21% coverage (gate 95%).
+
 ## 2026-05-13 — v0.3.0 — wire-shape change: AP2 routing moves to Subject.dimensions
 
 **Author:** v0.3.0 release, prompted by a live integration smoke test against `cycles-server:0.1.25.18`
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 921fa69..36135c3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,14 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Changed
+- `runcycles` dependency floor raised from `>=0.4.1` to `>=0.5.0`. runcycles 0.5.0 ships durable commit retries (on-disk journal with replay, `POST /v1/events` fallback for expired commits, 429/auth handling that never releases spent budget). No guard code changes: the guard calls `commit_reservation` directly, so the documented commit-uncertainty exception contract (`AP2GuardCommitUncertain` / `AP2GuardCommitFailed`) is unchanged.
+
+### Unchanged
+- Public Python API, wire shape, idempotency-key derivation, exception contract.
+
 ## [0.3.0] — 2026-05-13
 
 ### Changed (wire shape)
diff --git a/pyproject.toml b/pyproject.toml
index 6523575..f7e4993 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -60,7 +60,7 @@ classifiers = [
     "Typing :: Typed",
 ]
 dependencies = [
-    "runcycles>=0.4.1",
+    "runcycles>=0.5.0",
     "pydantic>=2.0",
 ]