Merge commit '36c66dd290d3ce6eb1ccd310d0c658d4a32bb8eb' as 'repos/effect'

repos/effect/.changeset/add-flag-hidden.md

@@ -0,0 +1,15 @@
+---
+"effect": patch
+---
+
+Add `Flag.withHidden` (and `Param.withHidden`) to hide flags from `--help` output and shell completions while keeping them fully parseable on the command line.
+
+Useful for experimental, internal, or deprecated flags that should be accepted but not advertised, e.g. `--experimental-foo`, debug toggles, or escape hatches that are not yet committed to the public CLI surface.
+
+```ts
+import { Flag } from "effect/unstable/cli"
+
+const experimental = Flag.boolean("experimental-foo").pipe(
+  Flag.withHidden
+)
+```