diff --git a/apps/server/src/vcs/GitVcsDriverCore.test.ts b/apps/server/src/vcs/GitVcsDriverCore.test.ts
index d46666cb468d0..e073c704ee138 100644
--- a/apps/server/src/vcs/GitVcsDriverCore.test.ts
+++ b/apps/server/src/vcs/GitVcsDriverCore.test.ts
@@ -722,6 +722,26 @@ it.effect("reads a branch whose name starts with a parenthesis as attached", ()
   ).pipe(Effect.provide(layerTest)),
 );
 
+it.effect("follows a checkout made outside the driver after refs were cached", () =>
+  Effect.scoped(
+    Effect.gen(function* () {
+      const cwd = yield* makeTmpDir();
+      const { initialBranch } = yield* initRepoWithCommit(cwd);
+      yield* git(cwd, ["branch", "feature/outside"]);
+      const driver = yield* GitVcsDriver.GitVcsDriver;
+      yield* driver.listRefs({ cwd });
+
+      yield* git(cwd, ["switch", "feature/outside"]);
+
+      const refs = (yield* driver.listRefs({ cwd })).refs;
+      const previous = refs.find((ref) => ref.name === initialBranch);
+      assert.isTrue(refs.find((ref) => ref.name === "feature/outside")?.current);
+      assert.isFalse(previous?.current);
+      assert.isNull(previous?.worktreePath ?? null);
+    }),
+  ).pipe(Effect.provide(layerTest)),
+);
+
 it.effect.each(["on a branch", "detached", "unborn"] as const)(
   "reads only the repository root for review requests that ignore the branch when %s",
   (state) =>
diff --git a/apps/server/src/vcs/GitVcsDriverCore.ts b/apps/server/src/vcs/GitVcsDriverCore.ts
index 32042a0ff5e5f..bb84cda7d75a5 100644
--- a/apps/server/src/vcs/GitVcsDriverCore.ts
+++ b/apps/server/src/vcs/GitVcsDriverCore.ts
@@ -1495,23 +1495,23 @@ export const makeGitVcsDriverCore = Effect.fn("makeGitVcsDriverCore")(function*
       : null;
   });
 
+  const readCurrentBranch = (operation: string, cwd: string) =>
+    executeGit(operation, cwd, ["symbolic-ref", "--quiet", "HEAD"], {
+      timeoutMs: 5_000,
+      allowNonZeroExit: true,
+    }).pipe(
+      Effect.map((result) => (result.exitCode === 0 ? branchNameFromHeadRef(result.stdout) : null)),
+    );
+
   const resolveRepositoryPathsUncached = Effect.fn("resolveRepositoryPathsUncached")(function* (
     cwd: string,
   ) {
     const gitCommonDir = yield* readGitCommonDir(cwd);
     if (gitCommonDir === null) return null;
-    const [worktreeRoot, currentBranchResult] = yield* Effect.all(
+    const [worktreeRoot, currentBranch] = yield* Effect.all(
       [
         readWorktreeRoot(cwd),
-        executeGit(
-          "GitVcsDriver.resolveRepositoryPaths.currentBranch",
-          cwd,
-          ["symbolic-ref", "--quiet", "HEAD"],
-          {
-            timeoutMs: 5_000,
-            allowNonZeroExit: true,
-          },
-        ),
+        readCurrentBranch("GitVcsDriver.resolveRepositoryPaths.currentBranch", cwd),
       ],
       { concurrency: 2 },
     );
@@ -1523,8 +1523,6 @@ export const makeGitVcsDriverCore = Effect.fn("makeGitVcsDriverCore")(function*
             Effect.map((physicalCwd) => path.relative(worktreeRoot, physicalCwd) === ""),
             Effect.orElseSucceed(() => undefined),
           );
-    const currentBranch =
-      currentBranchResult.exitCode === 0 ? branchNameFromHeadRef(currentBranchResult.stdout) : null;
 
     return {
       gitCommonDir,
@@ -4448,22 +4446,33 @@ export const makeGitVcsDriverCore = Effect.fn("makeGitVcsDriverCore")(function*
         };
       }
 
-      const snapshot = yield* resolveListRefsSnapshot(
-        repositoryPaths.gitCommonDir,
-        input.refresh === true,
+      // Both caches outlive a checkout made outside T3 Code, so this checkout's branch is read
+      // on every call and replaces whatever the cached snapshot claims for it.
+      const [snapshot, currentBranch] = yield* Effect.all(
+        [
+          resolveListRefsSnapshot(repositoryPaths.gitCommonDir, input.refresh === true),
+          readCurrentBranch("GitVcsDriver.listRefs.currentBranch", input.cwd).pipe(
+            Effect.orElseSucceed(() => repositoryPaths.currentBranch),
+          ),
+        ],
+        { concurrency: 2 },
       );
-      const hasCurrentWorktreeBranch =
-        repositoryPaths.worktreeRoot !== null &&
-        snapshot.localBranches.some((ref) => ref.worktreePath === repositoryPaths.worktreeRoot);
-      const localBranches = snapshot.localBranches.map((ref) => ({
-        ...ref,
-        worktreePath:
-          ref.worktreePath ??
-          (ref.name === repositoryPaths.currentBranch ? repositoryPaths.worktreeRoot : null),
-        current: hasCurrentWorktreeBranch
-          ? ref.worktreePath === repositoryPaths.worktreeRoot
-          : ref.name === repositoryPaths.currentBranch,
-      }));
+      const { worktreeRoot } = repositoryPaths;
+      const localBranches = snapshot.localBranches.map((ref) => {
+        const current = ref.name === currentBranch;
+        return {
+          ...ref,
+          worktreePath:
+            worktreeRoot === null
+              ? ref.worktreePath
+              : current
+                ? worktreeRoot
+                : ref.worktreePath === worktreeRoot
+                  ? null
+                  : ref.worktreePath,
+          current,
+        };
+      });
       const combinedBranches = input.includeMatchingRemoteRefs
         ? [...localBranches, ...snapshot.remoteBranches]
         : dedupeRemoteBranchesWithLocalMatches([...localBranches, ...snapshot.remoteBranches]);
diff --git a/apps/web/src/components/BranchToolbar.logic.test.ts b/apps/web/src/components/BranchToolbar.logic.test.ts
index d5b74f1cb1168..4049031b57c43 100644
--- a/apps/web/src/components/BranchToolbar.logic.test.ts
+++ b/apps/web/src/components/BranchToolbar.logic.test.ts
@@ -192,6 +192,7 @@ describe("resolveBranchSelectionTarget", () => {
       checkoutCwd: "/repo",
       nextWorktreePath: "/repo",
       reuseExistingWorktree: true,
+      staysInActiveCheckout: false,
     });
     expect(
       resolveBranchSelectionTarget({
@@ -206,6 +207,7 @@ describe("resolveBranchSelectionTarget", () => {
       checkoutCwd: "/repo/.t3/worktrees/feature-b",
       nextWorktreePath: "/repo/.t3/worktrees/feature-b",
       reuseExistingWorktree: true,
+      staysInActiveCheckout: false,
     });
   });
 
@@ -233,6 +235,8 @@ describe("resolveBranchSelectionTarget", () => {
         checkoutCwd: "/repo",
         nextWorktreePath: null,
         reuseExistingWorktree: true,
+        // A ref listed in the thread's own checkout may be stale, so it is checked out, not assumed.
+        staysInActiveCheckout: activeWorktreePath === null,
       });
     }
   });
@@ -251,6 +255,7 @@ describe("resolveBranchSelectionTarget", () => {
       checkoutCwd: "/repo/.t3/worktrees/feature-a",
       nextWorktreePath: "/repo/.t3/worktrees/feature-a",
       reuseExistingWorktree: false,
+      staysInActiveCheckout: true,
     });
   });
 });
diff --git a/apps/web/src/components/BranchToolbar.logic.ts b/apps/web/src/components/BranchToolbar.logic.ts
index 5dec87e3d73d7..274ec098f2f11 100644
--- a/apps/web/src/components/BranchToolbar.logic.ts
+++ b/apps/web/src/components/BranchToolbar.logic.ts
@@ -257,6 +257,7 @@ export function resolveBranchSelectionTarget(input: {
   checkoutCwd: string;
   nextWorktreePath: string | null;
   reuseExistingWorktree: boolean;
+  staysInActiveCheckout: boolean;
 } {
   const { activeProjectCwd, activeWorktreePath, refName } = input;
 
@@ -266,10 +267,13 @@ export function resolveBranchSelectionTarget(input: {
       input.activeProjectCheckoutRoot === undefined
         ? workspaceRelativeFilePath(activeProjectCwd, refName.worktreePath) !== null
         : workspaceRelativeFilePath(input.activeProjectCheckoutRoot, refName.worktreePath) === ".";
+    const nextWorktreePath = isProjectCheckout ? null : refName.worktreePath;
     return {
       checkoutCwd: refName.worktreePath,
-      nextWorktreePath: isProjectCheckout ? null : refName.worktreePath,
+      nextWorktreePath,
       reuseExistingWorktree: true,
+      // Listed refs can predate a checkout made outside the picker, so only Git can confirm this one.
+      staysInActiveCheckout: nextWorktreePath === activeWorktreePath,
     };
   }
 
@@ -280,6 +284,7 @@ export function resolveBranchSelectionTarget(input: {
     checkoutCwd: nextWorktreePath ?? activeProjectCwd,
     nextWorktreePath,
     reuseExistingWorktree: false,
+    staysInActiveCheckout: nextWorktreePath === activeWorktreePath,
   };
 }
 
diff --git a/apps/web/src/components/BranchToolbarBranchSelector.tsx b/apps/web/src/components/BranchToolbarBranchSelector.tsx
index 2b59c126e2a6b..7bb3ceb08eae7 100644
--- a/apps/web/src/components/BranchToolbarBranchSelector.tsx
+++ b/apps/web/src/components/BranchToolbarBranchSelector.tsx
@@ -445,7 +445,10 @@ export function BranchToolbarBranchSelector({
     )
       return;
 
-    if (selectionTarget.reuseExistingWorktree) {
+    if (
+      selectionTarget.reuseExistingWorktree &&
+      !(selectionTarget.staysInActiveCheckout && canWriteSourceControl)
+    ) {
       setThreadBranch(refName.name, selectionTarget.nextWorktreePath);
       setIsBranchMenuOpen(false);
       onComposerFocusRequest?.();