diff --git a/CHANGELOG.md b/CHANGELOG.md
index d2aaf1d..ffd8656 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,14 @@
 # Changelog
 
+## 0.6.3
+
+- **macOS version gate**: `run` and `models` refuse to start on macOS older than 27.0 (or on non-macOS hosts), exiting with code 2 and naming both the detected version and the latest supported macOS (`27.0+`).
+- **Doctor diagnostics**: `fm-bench doctor` still runs on unsupported hosts so it can report the macOS mismatch, the latest supported version, and a failed `fm` probe instead of hard-exiting first.
+- **Supported platforms doc**: new [docs/supported-platforms.md](docs/supported-platforms.md) describing the fixed macOS requirement and which commands are gated.
+- **Package metadata**: `package.json` now declares `"os": ["darwin"]` so npm marks the package as macOS-only.
+- **Pack integrity**: `npm run check:pack` (wired into `prepack`) walks runtime imports and fails if any required file is missing from the published tarball.
+- **Verified** on macOS 27.0 build `26A5378n` (Apple M5 Pro) with the installed `fm` CLI: doctor, quick/standard benchmarks, validate/export/history, and CI-style SLO runs all passed.
+
 ## 0.6.2
 
 - **macOS 27 beta 3 compatibility**: verified on macOS 27.0 beta 3 build `26A5378j` with the installed `fm` CLI and Xcode 26.6 toolchain.
diff --git a/README.md b/README.md
index 97767dc..f995441 100644
--- a/README.md
+++ b/README.md
@@ -30,7 +30,7 @@ fm-bench
 One command discovers your models, runs the standard prompt suite, and prints a full benchmark report:
 
 ```text
-fm-bench 0.6.2 | darwin/arm64 | fm
+fm-bench 0.6.3 | darwin/arm64 | fm
 prompts 3 | runs 5 | concurrency 1 | stream on | measured 15 | failed 0 | skipped 0 | elapsed 38.20s
 
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