diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index e20d618d2..ad20267ca 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -195,6 +195,28 @@ openshell --help
 openshell sandbox create -- codex
 ```
 
+### Rust build cache
+
+Mise preserves an existing `SCCACHE_DIR` so each environment can choose where
+to store compiler cache entries. When `SCCACHE_DIR` is unset, OpenShell uses
+the worktree-local `.cache/sccache` directory. To make cache entries available
+to multiple worktrees on a workstation, set the variable to a user-level
+directory before activating mise. For example:
+
+```shell
+export SCCACHE_DIR="$HOME/.cache/openshell/sccache"
+```
+
+CI can select a different directory or configure a remote sccache backend
+without changing the workstation setting. Cargo output remains in each
+worktree's `target/` directory.
+
+OpenShell does not set `SCCACHE_BASEDIRS`. Sccache loads base directories when
+its machine-local daemon starts, but the correct workspace root differs for
+each worktree. Cache reuse therefore depends on the compiler inputs: outputs
+that embed absolute paths, including Rust dependencies in some builds, can
+still miss across worktrees.
+
 ## Main Tasks
 
 These are the primary `mise` tasks for day-to-day development:
diff --git a/mise.toml b/mise.toml
index fc5ba340a..a5d968210 100644
--- a/mise.toml
+++ b/mise.toml
@@ -53,11 +53,10 @@ _.file = [".env"]
 KUBECONFIG = "{{config_root}}/kubeconfig"
 UV_CACHE_DIR = "{{config_root}}/.cache/uv"
 
-# Enable sccache for faster Rust builds.
-# Local builds use a disk cache (SCCACHE_DIR); CI sets SCCACHE_MEMCACHED_ENDPOINT
-# via repository variables to use a shared memcached backend instead.
+# Enable sccache for faster Rust builds. Preserve an SCCACHE_DIR selected by the
+# caller so workstations and CI can configure their cache locations separately.
 RUSTC_WRAPPER = "sccache"
-SCCACHE_DIR = "{{config_root}}/.cache/sccache"
+SCCACHE_DIR = "{{ get_env(name='SCCACHE_DIR', default=config_root ~ '/.cache/sccache') }}"
 
 # Shared build constants (overridable via environment).
 # DOCKER_BUILDKIT enables BuildKit for Docker; ignored by podman.