diff --git a/crates/local-deployment/src/container.rs b/crates/local-deployment/src/container.rs
index be28726a5e..877960440c 100644
--- a/crates/local-deployment/src/container.rs
+++ b/crates/local-deployment/src/container.rs
@@ -310,7 +310,7 @@ impl LocalContainerService {
     }
 
     async fn cleanup_expired_workspaces(&self) -> Result<(), DeploymentError> {
-        if std::env::var("DISABLE_WORKTREE_CLEANUP").is_ok() {
+        if utils::env::disable_flag_set("DISABLE_WORKTREE_CLEANUP") {
             tracing::info!(
                 "Expired workspace cleanup is disabled via DISABLE_WORKTREE_CLEANUP environment variable"
             );
@@ -348,7 +348,7 @@ impl LocalContainerService {
         const IDLE_REAP_HOURS: i64 = 48;
         const ACTIVITY_GRACE_SECS: i64 = 60;
 
-        if std::env::var("DISABLE_CLI_SESSION_REAP").is_ok() {
+        if utils::env::disable_flag_set("DISABLE_CLI_SESSION_REAP") {
             return;
         }
         let sessions = match crate::pty::list_cli_tmux_sessions().await {
diff --git a/crates/local-deployment/src/loop_supervisor.rs b/crates/local-deployment/src/loop_supervisor.rs
index f0e097c9d8..46aaf2623e 100644
--- a/crates/local-deployment/src/loop_supervisor.rs
+++ b/crates/local-deployment/src/loop_supervisor.rs
@@ -358,7 +358,7 @@ pub struct LoopSupervisor;
 impl LoopSupervisor {
     pub fn spawn(db: DBService) {
         tokio::spawn(async move {
-            if std::env::var(DISABLE_ENV).is_ok() {
+            if utils::env::disable_flag_set(DISABLE_ENV) {
                 tracing::info!("{DISABLE_ENV} set; loop automation supervisor disabled");
                 return;
             }
diff --git a/crates/utils/src/env.rs b/crates/utils/src/env.rs
index 5bc6a79dc7..044a407008 100644
--- a/crates/utils/src/env.rs
+++ b/crates/utils/src/env.rs
@@ -62,6 +62,40 @@ pub(crate) fn normalize_path_override(name: &str, value: Option<OsString>) -> Op
     }
 }
 
+/// Check a `DISABLE_*` style opt-out flag.
+///
+/// Any value — including `0`, `false` and the empty string — disables the gated
+/// behaviour. That is deliberately unchanged from the original
+/// `std::env::var(..).is_ok()` gate: several of these flags guard destructive
+/// cleanup, so tightening them such that `DISABLE_X=0` means "enabled" would
+/// silently switch worktree deletion back on for anyone relying on the previous
+/// behaviour. The surprising case is reported instead of reinterpreted.
+pub fn disable_flag_set(name: &str) -> bool {
+    evaluate_disable_flag(name, std::env::var(name).ok())
+}
+
+/// Evaluate an opt-out flag without reading the environment, so the warning
+/// behaviour is testable.
+pub(crate) fn evaluate_disable_flag(name: &str, value: Option<String>) -> bool {
+    let Some(value) = value else {
+        return false;
+    };
+
+    if matches!(
+        value.trim().to_ascii_lowercase().as_str(),
+        "" | "0" | "false" | "no" | "off"
+    ) {
+        tracing::warn!(
+            variable = name,
+            value = %value,
+            "Opt-out flag is set to a falsy-looking value but still DISABLES the \
+             gated behaviour; unset the variable entirely to re-enable it"
+        );
+    }
+
+    true
+}
+
 fn select_env_var_with_legacy<F>(lookup: F, new_name: &str, legacy_name: &str) -> Option<String>
 where
     F: Fn(&str) -> Option<String>,
@@ -86,6 +120,28 @@ mod tests {
         )
     }
 
+    #[test]
+    fn disable_flag_is_unset_when_variable_is_absent() {
+        assert!(!evaluate_disable_flag("DISABLE_X", None));
+    }
+
+    #[test]
+    fn disable_flag_is_set_for_a_truthy_value() {
+        assert!(evaluate_disable_flag("DISABLE_X", Some("1".to_string())));
+    }
+
+    /// The whole point of the helper: falsy-looking values still disable, so a
+    /// bug fix can never silently re-enable destructive cleanup.
+    #[test]
+    fn falsy_looking_values_still_disable() {
+        for value in ["0", "false", "no", "off", "", "  FALSE  "] {
+            assert!(
+                evaluate_disable_flag("DISABLE_X", Some(value.to_string())),
+                "{value:?} should still disable"
+            );
+        }
+    }
+
     #[test]
     fn returns_legacy_value_when_only_legacy_is_set() {
         assert_eq!(
diff --git a/crates/workspace-manager/src/workspace_manager.rs b/crates/workspace-manager/src/workspace_manager.rs
index 6545982116..d1534e60b8 100644
--- a/crates/workspace-manager/src/workspace_manager.rs
+++ b/crates/workspace-manager/src/workspace_manager.rs
@@ -537,7 +537,7 @@ impl WorkspaceManager {
     }
 
     pub async fn cleanup_orphan_workspaces(&self) {
-        if std::env::var("DISABLE_WORKTREE_CLEANUP").is_ok() {
+        if utils::env::disable_flag_set("DISABLE_WORKTREE_CLEANUP") {
             info!(
                 "Orphan workspace cleanup is disabled via DISABLE_WORKTREE_CLEANUP environment variable"
             );