Land release blocker fixes and workspace cleanup

docs/issues/keystore-thread-safety.md

@@ -4,6 +4,28 @@
 **Path:** `crates/cloud-providers/src/keystore.rs:6-18`
 **Source:** [2026-04-22 code review](../code-review-2026-04-22.md)
 **Labels:** release-blocker, major, unsafe-api, cloud
+**Status:** RESOLVED (2026-04-22)
+
+## Resolution
+
+Chose acceptance option 2. The environment-mutation stub is gone;
+`store_api_key` now writes into a process-global
+`OnceLock<Mutex<HashMap<String, String>>>`, so the safe signature matches
+the actual safety properties.
+
+Additional details:
+
+- Stored keys now live in-memory only for the life of the process.
+- `retrieve_api_key` checks the in-memory keystore first, then falls
+  back to read-only `KON_API_KEY_<PROVIDER>` environment variables so
+  externally injected secrets still work.
+- Module docs now describe the real tradeoff clearly: safe from any
+  thread, but non-persistent until a proper OS keychain backend lands.
+
+Regression tests:
+
+- `stored_key_is_retrievable_without_env_mutation`
+- `providers_do_not_overlap`
 
 ## Problem