@@ -202,14 +202,15 @@ describe("fillNewTaskWorkspaceBranch", () => {
 });
 
 describe("resolveWorktreeSwitchBranch", () => {
-  const input = { selectedBranch: "feature", checkoutBranch: "feature", worktreeBaseBranch: "dev" };
-
-  it("drops the checkout branch so the configured base applies", () => {
-    expect(resolveWorktreeSwitchBranch(input)).toBeNull();
+  it("starts a new worktree from the configured base, not the checkout's branch", () => {
+    expect(
+      resolveWorktreeSwitchBranch({ selectedBranch: "release", worktreeBaseBranch: "dev" }),
+    ).toBeNull();
   });
 
-  it("keeps another branch the user chose, and today's behavior without a base", () => {
-    expect(resolveWorktreeSwitchBranch({ ...input, selectedBranch: "release" })).toBe("release");
-    expect(resolveWorktreeSwitchBranch({ ...input, worktreeBaseBranch: "" })).toBe("feature");
+  it("keeps today's behavior without a configured base", () => {
+    expect(resolveWorktreeSwitchBranch({ selectedBranch: "release", worktreeBaseBranch: "" })).toBe(
+      "release",
+    );
   });
 });
@@ -72,15 +72,12 @@ export function resolveNewTaskLocalWorkspaceSelection(input: {
   };
 }
 
-/** Leaving the checkout for a new worktree drops the checkout's branch when a base is configured. */
+/** A checkout's branch is not a worktree base, so leaving it for a new worktree starts from the configured base. */
 export function resolveWorktreeSwitchBranch(input: {
   readonly selectedBranch: string | null;
-  readonly checkoutBranch: string | null;
   readonly worktreeBaseBranch: string;
 }): string | null {
-  return input.worktreeBaseBranch !== "" && input.selectedBranch === input.checkoutBranch
-    ? null
-    : input.selectedBranch;
+  return input.worktreeBaseBranch === "" ? input.selectedBranch : null;
 }
 
 export function resolveNewTaskBranchLabel(input: {
 
@@ -695,7 +695,6 @@ export function NewTaskFlowProvider(
             : workspaceMode === "local"
               ? resolveWorktreeSwitchBranch({
                   selectedBranch: selectedBranchName,
-                  checkoutBranch: localSelection.branch,
                   worktreeBaseBranch: projectSettings.settings.newWorktreesBaseBranch,
                 })
               : selectedBranchName,
 
@@ -20,7 +20,7 @@ import { toastManager } from "../ui/toast";
 import { resolveAppModelSelectionForInstance } from "../../modelSelection";
 import {
   resolveNewDraftStartFromOrigin,
-  shouldClearSyncedDraftBranch,
+  shouldResetBranchForNewWorktree,
 } from "../../lib/chatThreadActions";
 import { type DraftThreadEnvMode, useComposerDraftStore } from "../../composerDraftStore";
 import {
@@ -237,11 +237,10 @@ export function useComposerSelection(input: ComposerSelectionInput) {
           newWorktreesStartFromOrigin: activeProjectSettings.settings.newWorktreesStartFromOrigin,
         }),
         ...(mode === "worktree" && draftThread?.worktreePath ? { worktreePath: null } : {}),
-        ...(shouldClearSyncedDraftBranch({
+        ...(shouldResetBranchForNewWorktree({
+          currentEnvMode: draftThread?.envMode,
           nextEnvMode: mode,
           worktreeBaseBranch: activeProjectSettings.settings.newWorktreesBaseBranch,
-          draftBranch: draftThread?.branch ?? null,
-          environmentSelection: draftThread?.environmentSelection,
         })
           ? { branch: null }
           : {}),
 
@@ -2,7 +2,7 @@ import { ProviderInstanceId, type ModelSelection } from "@t3tools/contracts";
 import { describe, expect, it } from "vite-plus/test";
 import {
   resolveNewThreadModelSelectionOverride,
-  shouldClearSyncedDraftBranch,
+  shouldResetBranchForNewWorktree,
 } from "./chatThreadActions";
 
 const PROJECT_DEFAULT_SELECTION: ModelSelection = {
@@ -38,25 +38,29 @@ describe("chatThreadActions", () => {
   });
 });
 
-describe("shouldClearSyncedDraftBranch", () => {
+describe("shouldResetBranchForNewWorktree", () => {
   const input = {
+    currentEnvMode: "local",
     nextEnvMode: "worktree",
     worktreeBaseBranch: "dev",
-    draftBranch: "feature/checked-out",
-    environmentSelection: "auto",
   } as const;
 
-  it("drops the checkout branch so a new worktree starts from the configured base", () => {
-    expect(shouldClearSyncedDraftBranch(input)).toBe(true);
-    expect(shouldClearSyncedDraftBranch({ ...input, environmentSelection: undefined })).toBe(true);
+  it("starts a new worktree from the configured base instead of the checkout's branch", () => {
+    expect(shouldResetBranchForNewWorktree(input)).toBe(true);
   });
 
-  it("keeps a branch the user picked", () => {
-    expect(shouldClearSyncedDraftBranch({ ...input, environmentSelection: "manual" })).toBe(false);
+  it("keeps a base already picked in worktree mode", () => {
+    expect(shouldResetBranchForNewWorktree({ ...input, currentEnvMode: "worktree" })).toBe(false);
   });
 
-  it("keeps today's behavior without a configured base or outside worktree mode", () => {
-    expect(shouldClearSyncedDraftBranch({ ...input, worktreeBaseBranch: "" })).toBe(false);
-    expect(shouldClearSyncedDraftBranch({ ...input, nextEnvMode: "local" })).toBe(false);
+  it("keeps today's behavior without a configured base or when leaving worktree mode", () => {
+    expect(shouldResetBranchForNewWorktree({ ...input, worktreeBaseBranch: "" })).toBe(false);
+    expect(
+      shouldResetBranchForNewWorktree({
+        currentEnvMode: "worktree",
+        nextEnvMode: "local",
+        worktreeBaseBranch: "dev",
+      }),
+    ).toBe(false);
   });
 });
@@ -43,18 +43,16 @@ export function resolveNewDraftStartFromOrigin(input: {
   return input.envMode === "worktree" && input.newWorktreesStartFromOrigin;
 }
 
-/** A configured base replaces the branch a draft synced from its checkout, never one the user picked. */
-export function shouldClearSyncedDraftBranch(input: {
+/** A checkout's branch is not a worktree base, so leaving it for a new worktree starts from the configured base. */
+export function shouldResetBranchForNewWorktree(input: {
+  currentEnvMode: DraftThreadEnvMode | undefined;
   nextEnvMode: DraftThreadEnvMode;
   worktreeBaseBranch: string;
-  draftBranch: string | null;
-  environmentSelection: "auto" | "manual" | undefined;
 }): boolean {
   return (
+    input.currentEnvMode === "local" &&
     input.nextEnvMode === "worktree" &&
-    input.worktreeBaseBranch !== "" &&
-    input.draftBranch !== null &&
-    input.environmentSelection !== "manual"
+    input.worktreeBaseBranch !== ""
   );
 }