diff --git a/src/shared/worktree/host-qualified-identity.test.ts b/src/shared/worktree/host-qualified-identity.test.ts
index 9b866e5d044..f6237005b28 100644
--- a/src/shared/worktree/host-qualified-identity.test.ts
+++ b/src/shared/worktree/host-qualified-identity.test.ts
@@ -63,4 +63,25 @@ describe('worktree host identity', () => {
   it('rejects identities without a host separator', () => {
     expect(getExecutionHostIdFromWorktreeHostIdentity('ssh:build-box')).toBeUndefined()
   })
+
+  // An unqualified row must not be assumed local: a destructive action keyed off
+  // this would then run against the wrong host.
+  it('leaves an unqualified identity without a host', () => {
+    expect(
+      getExecutionHostIdFromWorktreeHostIdentity(
+        composeWorktreeHostIdentity(undefined, WORKTREE_ID)
+      )
+    ).toBeUndefined()
+  })
+
+  it('recovers the host from a qualified identity', () => {
+    expect(
+      getExecutionHostIdFromWorktreeHostIdentity(composeWorktreeHostIdentity('local', WORKTREE_ID))
+    ).toBe('local')
+    expect(
+      getExecutionHostIdFromWorktreeHostIdentity(
+        composeWorktreeHostIdentity(toSshExecutionHostId('build-box'), WORKTREE_ID)
+      )
+    ).toBe(toSshExecutionHostId('build-box'))
+  })
 })
diff --git a/src/shared/worktree/host-qualified-identity.ts b/src/shared/worktree/host-qualified-identity.ts
index 9733aed2dd5..dcdc4411724 100644
--- a/src/shared/worktree/host-qualified-identity.ts
+++ b/src/shared/worktree/host-qualified-identity.ts
@@ -39,6 +39,13 @@ export function composeWorktreeHostIdentity(
   return `${hostId ?? ''}${HOST_SEPARATOR}${worktreeId}`
 }
 
+/**
+ * The host back out of an identity, when the identity names one.
+ *
+ * An empty prefix (`|<worktreeId>`) stays undefined rather than defaulting to
+ * `local`: an unqualified row may be on any host, and callers use this to pick
+ * the host a destructive action runs against.
+ */
 export function getExecutionHostIdFromWorktreeHostIdentity(
   identity: string
 ): ExecutionHostId | undefined {