feat(agent-manager): default base branch selection and BranchSelect component (#6701)

- Add persistent default base branch with picker dialog
- Extract BranchSelect reusable component from duplicated branch list UI
- Add base-branch.ts pure logic module with normalizeBaseBranch/chooseBaseBranch
- Add isCheckedOut flag to branch list items
- Update WorktreeStateManager to persist defaultBaseBranch
- Add i18n keys for all 16 locales
- Add unit tests for base-branch logic
- Update architecture tests

packages/kilo-vscode/src/agent-manager/AgentManagerProvider.ts

@@ -9,6 +9,7 @@ import { KiloProvider } from "../KiloProvider"
 import { buildWebviewHtml } from "../utils"
 import { WorktreeManager, type CreateWorktreeResult } from "./WorktreeManager"
 import { WorktreeStateManager } from "./WorktreeStateManager"
+import { chooseBaseBranch, normalizeBaseBranch } from "./base-branch"
 import { GitStatsPoller, type WorktreePresenceResult } from "./GitStatsPoller"
 import { GitOps, type ApplyConflict } from "./GitOps"
 import { versionedName } from "./branch-name"
@@ -281,6 +282,12 @@ export class AgentManagerProvider implements vscode.Disposable {
       return null
     }
 
+    if (type === "agentManager.setDefaultBaseBranch") {
+      const branch = normalizeBaseBranch(msg.branch as string | undefined)
+      this.state?.setDefaultBaseBranch(branch)
+      this.pushState()
+      return null
+    }
     if (type === "agentManager.requestExternalWorktrees") {
       void this.onRequestExternalWorktrees()
       return null
@@ -386,6 +393,31 @@ export class AgentManagerProvider implements vscode.Disposable {
   // Shared helpers
   // ---------------------------------------------------------------------------
 
+  /** Resolve the effective base branch using the configured default, explicit override, and existence check. */
+  private async resolveBaseBranch(
+    manager: WorktreeManager,
+    state: WorktreeStateManager,
+    explicit?: string,
+  ): Promise<string | undefined> {
+    const configured = state.getDefaultBaseBranch()
+    if (!configured && !explicit) return undefined
+
+    const configuredExists = configured ? await manager.branchExists(configured) : false
+    const result = chooseBaseBranch({ explicit, configured, configuredExists })
+
+    if (result.stale) {
+      this.clearStaleDefaultBaseBranch(state, result.stale)
+    }
+    return result.branch
+  }
+
+  /** Reset a stale default base branch and notify the webview. */
+  private clearStaleDefaultBaseBranch(state: WorktreeStateManager, stale: string): void {
+    this.log(`Default base branch "${stale}" no longer exists, clearing`)
+    state.setDefaultBaseBranch(undefined)
+    this.pushState()
+  }
+
   /** Create a git worktree on disk and register it in state. Returns null on failure. */
   private async createWorktreeOnDisk(opts?: {
     groupId?: string
@@ -411,11 +443,16 @@ export class AgentManagerProvider implements vscode.Disposable {
 
     this.postToWebview({ type: "agentManager.worktreeSetup", status: "creating", message: "Creating git worktree..." })
 
+    // Resolve effective base branch using configured default
+    const effectiveBase = opts?.existingBranch
+      ? undefined
+      : await this.resolveBaseBranch(manager, state, opts?.baseBranch)
+
     let result: CreateWorktreeResult
     try {
       result = await manager.createWorktree({
         prompt: opts?.name || "kilo",
-        baseBranch: opts?.baseBranch,
+        baseBranch: effectiveBase ?? opts?.baseBranch,
         branchName: opts?.branchName,
         existingBranch: opts?.existingBranch,
       })
@@ -940,10 +977,23 @@ export class AgentManagerProvider implements vscode.Disposable {
     try {
       const result = await manager.listBranches()
       const checkedOut = await manager.checkedOutBranches()
-      const filtered = result.branches.filter((b) => !checkedOut.has(b.name))
+
+      // Include isCheckedOut flag on each branch — let the webview decide how to filter
+      const branches = result.branches.map((b) => ({
+        ...b,
+        isCheckedOut: checkedOut.has(b.name),
+      }))
+
+      // Validate configured default branch still exists
+      const state = this.getStateManager()
+      const configured = state?.getDefaultBaseBranch()
+      if (configured && !branches.some((b) => b.name === configured)) {
+        this.clearStaleDefaultBaseBranch(state!, configured)
+      }
+
       this.postToWebview({
         type: "agentManager.branches",
-        branches: filtered,
+        branches,
         defaultBranch: result.defaultBranch,
       })
     } catch (error) {
@@ -1336,7 +1386,8 @@ export class AgentManagerProvider implements vscode.Disposable {
     if (!manager) return
     try {
       const branch = await manager.currentBranch()
-      this.postToWebview({ type: "agentManager.repoInfo", branch })
+      const defaultBranch = await manager.defaultBranch()
+      this.postToWebview({ type: "agentManager.repoInfo", branch, defaultBranch })
     } catch (error) {
       this.log(`Failed to get current branch: ${error}`)
     }
@@ -1409,6 +1460,7 @@ export class AgentManagerProvider implements vscode.Disposable {
       sessionsCollapsed: state.getSessionsCollapsed(),
       reviewDiffStyle: state.getReviewDiffStyle(),
       isGitRepo: true,
+      defaultBaseBranch: state.getDefaultBaseBranch(),
     })
 
     this.statsPoller.setEnabled(worktrees.length > 0 || this.panel !== undefined)

packages/kilo-vscode/src/agent-manager/WorktreeStateManager.ts

@@ -37,6 +37,7 @@ interface StateFile {
   tabOrder?: Record<string, string[]>
   sessionsCollapsed?: boolean
   reviewDiffStyle?: "unified" | "split"
+  defaultBaseBranch?: string
 }
 
 const STATE_FILE = "agent-manager.json"
@@ -55,6 +56,7 @@ export class WorktreeStateManager {
   private tabOrder: Record<string, string[]> = {}
   private collapsed = false
   private reviewDiffStyle: "unified" | "split" = "unified"
+  private defaultBase: string | undefined
   private readonly log: (msg: string) => void
   private saving: Promise<void> | undefined
   private pendingSave = false
@@ -245,6 +247,19 @@ export class WorktreeStateManager {
     void this.save()
   }
 
+  // ---------------------------------------------------------------------------
+  // Default base branch
+  // ---------------------------------------------------------------------------
+
+  getDefaultBaseBranch(): string | undefined {
+    return this.defaultBase
+  }
+
+  setDefaultBaseBranch(value: string | undefined): void {
+    this.defaultBase = value
+    void this.save()
+  }
+
   // ---------------------------------------------------------------------------
   // Persistence
   // ---------------------------------------------------------------------------
@@ -271,6 +286,7 @@ export class WorktreeStateManager {
       if (data.reviewDiffStyle === "split") {
         this.reviewDiffStyle = "split"
       }
+      this.defaultBase = data.defaultBaseBranch
       this.log(`Loaded state: ${this.worktrees.size} worktrees, ${this.sessions.size} sessions`)
     } catch (error) {
       const code = (error as NodeJS.ErrnoException).code
@@ -343,6 +359,9 @@ export class WorktreeStateManager {
     if (this.reviewDiffStyle === "split") {
       data.reviewDiffStyle = "split"
     }
+    if (this.defaultBase) {
+      data.defaultBaseBranch = this.defaultBase
+    }
 
     try {
       const dir = path.dirname(this.file)

packages/kilo-vscode/src/agent-manager/base-branch.ts

@@ -0,0 +1,34 @@
+/**
+ * Pure logic for resolving the effective base branch.
+ *
+ * Priority chain:
+ *   1. Explicit (per-worktree override, from dialog)
+ *   2. Configured default (persisted in agent-manager.json), if it still exists
+ *   3. Auto-detect (undefined → WorktreeManager.defaultBranch() at call site)
+ */
+
+/** Trim whitespace, return undefined for empty/blank. */
+export function normalizeBaseBranch(value: string | undefined): string | undefined {
+  if (!value) return undefined
+  const trimmed = value.trim()
+  return trimmed.length > 0 ? trimmed : undefined
+}
+
+/**
+ * Pick the effective base branch given an explicit override, a configured
+ * default, and whether that configured branch still exists in the repo.
+ *
+ * Returns `{ branch }` with the winner, and optionally `{ stale }` when the
+ * configured branch no longer exists (so the caller can clear it).
+ */
+export function chooseBaseBranch(opts: { explicit?: string; configured?: string; configuredExists?: boolean }): {
+  branch?: string
+  stale?: string
+} {
+  if (opts.explicit) return { branch: opts.explicit }
+  if (opts.configured) {
+    if (opts.configuredExists) return { branch: opts.configured }
+    return { stale: opts.configured }
+  }
+  return {}
+}

packages/kilo-vscode/src/agent-manager/git-import.ts

@@ -4,6 +4,7 @@ export interface BranchListItem {
   isRemote: boolean
   isDefault: boolean
   lastCommitDate?: string
+  isCheckedOut?: boolean
 }
 
 export interface PRUrlParts {

packages/kilo-vscode/tests/unit/agent-manager-arch.test.ts

@@ -25,6 +25,7 @@ const TSX_FILES = [
   path.join(ROOT, "webview-ui/agent-manager/review-annotations.ts"),
   path.join(ROOT, "webview-ui/agent-manager/MultiModelSelector.tsx"),
   path.join(ROOT, "webview-ui/agent-manager/ApplyDialog.tsx"),
+  path.join(ROOT, "webview-ui/agent-manager/BranchSelect.tsx"),
   path.join(ROOT, "webview-ui/agent-manager/WorktreeItem.tsx"),
 ]
 const TSX_FILE = TSX_FILES[0]
@@ -171,6 +172,7 @@ describe("Agent Manager Provider — onMessage routing", () => {
       "agentManager.requestRepoInfo",
       "agentManager.requestState",
       "agentManager.setTabOrder",
+      "agentManager.setDefaultBaseBranch",
     ]
     for (const msg of expected) {
       expect(text, `onMessage should handle "${msg}"`).toContain(msg)

packages/kilo-vscode/tests/unit/base-branch.test.ts

@@ -0,0 +1,59 @@
+import { describe, it, expect } from "bun:test"
+import { normalizeBaseBranch, chooseBaseBranch } from "../../src/agent-manager/base-branch"
+
+describe("normalizeBaseBranch", () => {
+  it("returns undefined for undefined input", () => {
+    expect(normalizeBaseBranch(undefined)).toBeUndefined()
+  })
+
+  it("returns undefined for empty string", () => {
+    expect(normalizeBaseBranch("")).toBeUndefined()
+  })
+
+  it("returns undefined for whitespace-only string", () => {
+    expect(normalizeBaseBranch("   ")).toBeUndefined()
+    expect(normalizeBaseBranch("\t\n")).toBeUndefined()
+  })
+
+  it("trims whitespace from valid input", () => {
+    expect(normalizeBaseBranch("  main  ")).toBe("main")
+    expect(normalizeBaseBranch(" develop\n")).toBe("develop")
+  })
+
+  it("returns the value as-is when already trimmed", () => {
+    expect(normalizeBaseBranch("main")).toBe("main")
+    expect(normalizeBaseBranch("feature/branch")).toBe("feature/branch")
+  })
+})
+
+describe("chooseBaseBranch", () => {
+  it("prefers explicit over configured", () => {
+    const result = chooseBaseBranch({ explicit: "release", configured: "develop", configuredExists: true })
+    expect(result).toEqual({ branch: "release" })
+  })
+
+  it("uses configured when it exists and no explicit is given", () => {
+    const result = chooseBaseBranch({ configured: "develop", configuredExists: true })
+    expect(result).toEqual({ branch: "develop" })
+  })
+
+  it("marks configured as stale when it no longer exists", () => {
+    const result = chooseBaseBranch({ configured: "old-branch", configuredExists: false })
+    expect(result).toEqual({ stale: "old-branch" })
+  })
+
+  it("falls back to auto-detect (undefined) when nothing is configured", () => {
+    const result = chooseBaseBranch({})
+    expect(result).toEqual({})
+  })
+
+  it("falls back to auto-detect when configured is undefined", () => {
+    const result = chooseBaseBranch({ configured: undefined, configuredExists: false })
+    expect(result).toEqual({})
+  })
+
+  it("explicit takes priority even when configured is stale", () => {
+    const result = chooseBaseBranch({ explicit: "main", configured: "deleted", configuredExists: false })
+    expect(result).toEqual({ branch: "main" })
+  })
+})

packages/kilo-vscode/webview-ui/agent-manager/AgentManagerApp.tsx

@@ -56,7 +56,6 @@ import { IconButton } from "@kilocode/kilo-ui/icon-button"
 import { Spinner } from "@kilocode/kilo-ui/spinner"
 import { Tooltip, TooltipKeybind } from "@kilocode/kilo-ui/tooltip"
 import { Popover } from "@kilocode/kilo-ui/popover"
-import { HoverCard } from "@kilocode/kilo-ui/hover-card"
 import { VSCodeProvider, useVSCode } from "../src/context/vscode"
 import { ServerProvider } from "../src/context/server"
 import { ProviderProvider } from "../src/context/provider"
@@ -85,6 +84,7 @@ import { FullScreenDiffView } from "./FullScreenDiffView"
 import { ApplyDialog } from "./ApplyDialog"
 import { groupApplyConflicts } from "./apply-conflicts"
 import type { ReviewComment } from "./review-comments"
+import { BranchSelect } from "./BranchSelect"
 import { WorktreeItem } from "./WorktreeItem"
 import "./agent-manager.css"
 
@@ -313,6 +313,11 @@ const AgentManagerContent: Component = () => {
   const [worktreesLoaded, setWorktreesLoaded] = createSignal(false)
   const [sessionsLoaded, setSessionsLoaded] = createSignal(false)
   const [isGitRepo, setIsGitRepo] = createSignal(true)
+  const [repoDetectedBranch, setRepoDetectedBranch] = createSignal<string | undefined>()
+  const [defaultBaseBranch, setDefaultBaseBranch] = createSignal<string | undefined>()
+
+  const repoDefaultBranch = () => defaultBaseBranch() ?? repoDetectedBranch() ?? "main"
+  const hasConfiguredBranch = () => !!defaultBaseBranch()
 
   const DEFAULT_SIDEBAR_WIDTH = 260
   const MIN_SIDEBAR_WIDTH = 200
@@ -1055,6 +1060,7 @@ const AgentManagerContent: Component = () => {
       if (msg.type === "agentManager.repoInfo") {
         const info = msg as AgentManagerRepoInfoMessage
         setRepoBranch(info.branch)
+        if (info.defaultBranch) setRepoDetectedBranch(info.defaultBranch)
       }
 
       if (msg.type === "agentManager.worktreeSetup") {
@@ -1114,6 +1120,7 @@ const AgentManagerContent: Component = () => {
         if (state.reviewDiffStyle === "split" || state.reviewDiffStyle === "unified") {
           setReviewDiffStyle(state.reviewDiffStyle)
         }
+        if ("defaultBaseBranch" in state) setDefaultBaseBranch(state.defaultBaseBranch || undefined)
         const current = session.currentSessionID()
         if (current) {
           const ms = state.sessions.find((s) => s.id === current)
@@ -1412,6 +1419,101 @@ const AgentManagerContent: Component = () => {
     vscode.postMessage({ type: "agentManager.configureSetupScript" })
   }
 
+  const handleChangeDefaultBaseBranch = () => {
+    const [search, setSearch] = createSignal("")
+    const [branches, setBranches] = createSignal<BranchInfo[]>([])
+    const [loading, setLoading] = createSignal(true)
+    const [highlighted, setHighlighted] = createSignal(-1)
+
+    const unsub = vscode.onMessage((msg) => {
+      if (msg.type === "agentManager.branches") {
+        const ev = msg as AgentManagerBranchesMessage
+        setBranches(ev.branches)
+        if (ev.defaultBranch) setRepoDetectedBranch(ev.defaultBranch)
+        setLoading(false)
+      }
+    })
+
+    vscode.postMessage({ type: "agentManager.requestBranches" })
+
+    const filtered = createMemo(() => {
+      const s = search().toLowerCase()
+      if (!s) return branches()
+      return branches().filter((b) => b.name.toLowerCase().includes(s))
+    })
+
+    const selectBranch = (name: string | undefined) => {
+      vscode.postMessage({ type: "agentManager.setDefaultBaseBranch", branch: name })
+      setDefaultBaseBranch(name)
+      unsub()
+      dialog.close()
+    }
+
+    const handleKeyDown = (e: KeyboardEvent) => {
+      const items = filtered()
+      // offset by 1 for auto-detect option (-1 = auto-detect)
+      const total = items.length + 1
+      if (e.key === "ArrowDown") {
+        e.preventDefault()
+        e.stopPropagation()
+        setHighlighted((prev) => Math.min(prev + 1, total - 2))
+      } else if (e.key === "ArrowUp") {
+        e.preventDefault()
+        e.stopPropagation()
+        setHighlighted((prev) => Math.max(prev - 1, -1))
+      } else if (e.key === "Enter") {
+        e.preventDefault()
+        e.stopPropagation()
+        const idx = highlighted()
+        if (idx === -1) {
+          selectBranch(undefined)
+        } else {
+          const branch = items[idx]
+          if (branch) selectBranch(branch.name)
+        }
+      } else if (e.key === "Escape") {
+        e.preventDefault()
+        e.stopPropagation()
+        unsub()
+        dialog.close()
+      }
+    }
+
+    dialog.show(() => (
+      <Dialog title={t("agentManager.worktree.defaultBaseBranch")} fit>
+        <div class="am-default-base-branch">
+          <BranchSelect
+            branches={filtered()}
+            loading={loading()}
+            search={search()}
+            onSearch={(v) => {
+              setSearch(v)
+              setHighlighted(-1)
+            }}
+            onSelect={(b) => selectBranch(b.name)}
+            onSearchKeyDown={handleKeyDown}
+            selected={defaultBaseBranch()}
+            highlighted={highlighted()}
+            onHighlight={setHighlighted}
+            searchPlaceholder={t("agentManager.dialog.searchBranches")}
+            emptyLabel={t("agentManager.import.noMatchingBranches")}
+            loadingLabel={t("agentManager.import.loadingBranches")}
+            defaultLabel={t("agentManager.dialog.branchBadge.default")}
+            remoteLabel={t("agentManager.dialog.branchBadge.remote")}
+            defaultName={defaultBaseBranch()}
+            autoOption={{
+              label: t("agentManager.worktree.defaultBaseBranchAuto"),
+              hint: repoDetectedBranch(),
+              active: !hasConfiguredBranch(),
+              highlighted: highlighted() === -1,
+              onSelect: () => selectBranch(undefined),
+            }}
+          />
+        </div>
+      </Dialog>
+    ))
+  }
+
   const handleShowKeyboardShortcuts = () => {
     const categories = buildShortcutCategories(kb(), t)
     dialog.show(() => (
@@ -1449,7 +1551,7 @@ const AgentManagerContent: Component = () => {
 
   // Advanced worktree dialog — opens a full dialog with prompt, versions, model, mode
   const showAdvancedWorktreeDialog = () => {
-    dialog.show(() => <NewWorktreeDialog onClose={() => dialog.close()} />)
+    dialog.show(() => <NewWorktreeDialog onClose={() => dialog.close()} defaultBaseBranch={repoDefaultBranch()} />)
   }
 
   const confirmDeleteWorktree = (worktreeId: string) => {
@@ -1849,6 +1951,12 @@ const AgentManagerContent: Component = () => {
                       <DropdownMenu.Item onSelect={handleConfigureSetupScript}>
                         <DropdownMenu.ItemLabel>{t("agentManager.worktree.setupScript")}</DropdownMenu.ItemLabel>
                       </DropdownMenu.Item>
+                      <DropdownMenu.Separator />
+                      <DropdownMenu.Item onSelect={handleChangeDefaultBaseBranch}>
+                        <DropdownMenu.ItemLabel>
+                          {t("agentManager.worktree.defaultBaseBranch")}: {repoDefaultBranch()}
+                        </DropdownMenu.ItemLabel>
+                      </DropdownMenu.Item>
                     </DropdownMenu.Content>
                   </DropdownMenu.Portal>
                 </DropdownMenu>
@@ -2435,7 +2543,7 @@ function sanitizeBranchName(name: string): string {
     .join("/")
 }
 
-const NewWorktreeDialog: Component<{ onClose: () => void }> = (props) => {
+const NewWorktreeDialog: Component<{ onClose: () => void; defaultBaseBranch?: string }> = (props) => {
   const { t } = useLanguage()
   const vscode = useVSCode()
   const session = useSession()
@@ -2445,7 +2553,7 @@ const NewWorktreeDialog: Component<{ onClose: () => void }> = (props) => {
   // --- Shared branch data (used by both New tab's base branch selector and Import tab) ---
   const [branches, setBranches] = createSignal<BranchInfo[]>([])
   const [branchesLoading, setBranchesLoading] = createSignal(false)
-  const [defaultBranch, setDefaultBranch] = createSignal("main")
+  const [defaultBranch, setDefaultBranch] = createSignal(props.defaultBaseBranch ?? "main")
   const [branchSearch, setBranchSearch] = createSignal("")
 
   // --- New tab state ---
@@ -2552,7 +2660,7 @@ const NewWorktreeDialog: Component<{ onClose: () => void }> = (props) => {
     if (msg.type === "agentManager.branches") {
       const ev = msg as AgentManagerBranchesMessage
       setBranches(ev.branches)
-      setDefaultBranch(ev.defaultBranch)
+      if (!props.defaultBaseBranch) setDefaultBranch(ev.defaultBranch)
       setBranchesLoading(false)
     }
     if (msg.type === "agentManager.importResult") {
@@ -2730,98 +2838,69 @@ const NewWorktreeDialog: Component<{ onClose: () => void }> = (props) => {
                         </button>
                       }
                     >
-                      <div class="am-dropdown-search">
-                        <Icon name="magnifying-glass" size="small" />
-                        <input
-                          class="am-dropdown-search-input"
-                          type="text"
-                          placeholder={t("agentManager.dialog.searchBranches")}
-                          value={branchSearch()}
-                          autofocus
-                          onInput={(e) => {
-                            setBranchSearch(e.currentTarget.value)
-                            setHighlightedIndex(0)
-                          }}
-                          onKeyDown={(e) => {
-                            const items = filteredBranches()
-                            if (e.key === "ArrowDown") {
-                              e.preventDefault()
-                              e.stopPropagation()
-                              const next = Math.min(highlightedIndex() + 1, items.length - 1)
-                              setHighlightedIndex(next)
-                              requestAnimationFrame(() => {
-                                document
-                                  .querySelector(`.am-branch-item[data-index="${next}"]`)
-                                  ?.scrollIntoView({ block: "nearest" })
-                              })
-                            } else if (e.key === "ArrowUp") {
-                              e.preventDefault()
-                              e.stopPropagation()
-                              const prev = Math.max(highlightedIndex() - 1, 0)
-                              setHighlightedIndex(prev)
-                              requestAnimationFrame(() => {
-                                document
-                                  .querySelector(`.am-branch-item[data-index="${prev}"]`)
-                                  ?.scrollIntoView({ block: "nearest" })
-                              })
-                            } else if (e.key === "Enter") {
-                              e.preventDefault()
-                              e.stopPropagation()
-                              const selected = items[highlightedIndex()]
-                              if (selected) {
-                                setBaseBranch(selected.name)
-                                setBaseBranchOpen(false)
-                                setBranchSearch("")
-                                setHighlightedIndex(0)
-                              }
-                            } else if (e.key === "Escape") {
-                              e.preventDefault()
-                              e.stopPropagation()
+                      <BranchSelect
+                        branches={filteredBranches()}
+                        loading={branchesLoading()}
+                        search={branchSearch()}
+                        onSearch={(v) => {
+                          setBranchSearch(v)
+                          setHighlightedIndex(0)
+                        }}
+                        onSelect={(b) => {
+                          setBaseBranch(b.name)
+                          setBaseBranchOpen(false)
+                          setBranchSearch("")
+                          setHighlightedIndex(0)
+                        }}
+                        onSearchKeyDown={(e) => {
+                          const items = filteredBranches()
+                          if (e.key === "ArrowDown") {
+                            e.preventDefault()
+                            e.stopPropagation()
+                            const next = Math.min(highlightedIndex() + 1, items.length - 1)
+                            setHighlightedIndex(next)
+                            requestAnimationFrame(() => {
+                              document
+                                .querySelector(`.am-branch-item[data-index="${next}"]`)
+                                ?.scrollIntoView({ block: "nearest" })
+                            })
+                          } else if (e.key === "ArrowUp") {
+                            e.preventDefault()
+                            e.stopPropagation()
+                            const prev = Math.max(highlightedIndex() - 1, 0)
+                            setHighlightedIndex(prev)
+                            requestAnimationFrame(() => {
+                              document
+                                .querySelector(`.am-branch-item[data-index="${prev}"]`)
+                                ?.scrollIntoView({ block: "nearest" })
+                            })
+                          } else if (e.key === "Enter") {
+                            e.preventDefault()
+                            e.stopPropagation()
+                            const selected = items[highlightedIndex()]
+                            if (selected) {
+                              setBaseBranch(selected.name)
                               setBaseBranchOpen(false)
                               setBranchSearch("")
                               setHighlightedIndex(0)
                             }
-                          }}
-                        />
-                      </div>
-                      <div class="am-dropdown-list">
-                        <For each={filteredBranches()}>
-                          {(branch, index) => (
-                            <button
-                              class="am-branch-item"
-                              classList={{
-                                "am-branch-item-active": effectiveBaseBranch() === branch.name,
-                                "am-branch-item-highlighted": highlightedIndex() === index(),
-                              }}
-                              data-index={index()}
-                              onClick={() => {
-                                setBaseBranch(branch.name)
-                                setBaseBranchOpen(false)
-                                setBranchSearch("")
-                                setHighlightedIndex(0)
-                              }}
-                              onMouseEnter={() => setHighlightedIndex(index())}
-                              type="button"
-                            >
-                              <span class="am-branch-item-left">
-                                <Icon name="branch" size="small" />
-                                <span class="am-branch-item-name">{branch.name}</span>
-                                <Show when={branch.isDefault}>
-                                  <span class="am-branch-badge">{t("agentManager.dialog.branchBadge.default")}</span>
-                                </Show>
-                                <Show when={!branch.isLocal && branch.isRemote}>
-                                  <span class="am-branch-badge am-branch-badge-remote">
-                                    {t("agentManager.dialog.branchBadge.remote")}
-                                  </span>
-                                </Show>
-                              </span>
-                              <Show when={branch.lastCommitDate}>
-                                <span class="am-branch-item-time">{formatRelativeDate(branch.lastCommitDate!)}</span>
-                              </Show>
-                            </button>
-                          )}
-                        </For>
-                      </div>
+                          } else if (e.key === "Escape") {
+                            e.preventDefault()
+                            e.stopPropagation()
+                            setBaseBranchOpen(false)
+                            setBranchSearch("")
+                            setHighlightedIndex(0)
+                          }
+                        }}
+                        selected={effectiveBaseBranch()}
+                        highlighted={highlightedIndex()}
+                        onHighlight={setHighlightedIndex}
+                        searchPlaceholder={t("agentManager.dialog.searchBranches")}
+                        emptyLabel={t("agentManager.import.noMatchingBranches")}
+                        defaultLabel={t("agentManager.dialog.branchBadge.default")}
+                        remoteLabel={t("agentManager.dialog.branchBadge.remote")}
+                        defaultName={defaultBranch()}
+                      />
                     </Popover>
                   </div>
                 </div>
@@ -3000,49 +3079,18 @@ const NewWorktreeDialog: Component<{ onClose: () => void }> = (props) => {
                   </button>
                 }
               >
-                <div class="am-dropdown-search">
-                  <Icon name="magnifying-glass" size="small" />
-                  <input
-                    class="am-dropdown-search-input"
-                    type="text"
-                    placeholder={t("agentManager.dialog.searchBranches")}
-                    value={branchSearch()}
-                    onInput={(e) => setBranchSearch(e.currentTarget.value)}
-                    autofocus
-                  />
-                </div>
-                <div class="am-dropdown-list">
-                  <Show
-                    when={filteredBranches().length > 0}
-                    fallback={
-                      <div class="am-dropdown-empty">
-                        {branchesLoading()
-                          ? t("agentManager.import.loadingBranches")
-                          : t("agentManager.import.noMatchingBranches")}
-                      </div>
-                    }
-                  >
-                    <For each={filteredBranches()}>
-                      {(branch) => (
-                        <div class="am-branch-item" onClick={() => handleBranchSelect(branch.name)}>
-                          <span class="am-branch-item-left">
-                            <Icon name="branch" size="small" />
-                            <span class="am-branch-item-name">{branch.name}</span>
-                            <Show when={branch.isDefault}>
-                              <span class="am-branch-badge">{t("agentManager.dialog.branchBadge.default")}</span>
-                            </Show>
-                            <Show when={!branch.isLocal && branch.isRemote}>
-                              <span class="am-branch-badge">{t("agentManager.dialog.branchBadge.remote")}</span>
-                            </Show>
-                          </span>
-                          <Show when={branch.lastCommitDate}>
-                            <span class="am-branch-item-time">{formatRelativeDate(branch.lastCommitDate!)}</span>
-                          </Show>
-                        </div>
-                      )}
-                    </For>
-                  </Show>
-                </div>
+                <BranchSelect
+                  branches={filteredBranches().filter((b) => !b.isCheckedOut)}
+                  loading={branchesLoading()}
+                  search={branchSearch()}
+                  onSearch={setBranchSearch}
+                  onSelect={(b) => handleBranchSelect(b.name)}
+                  searchPlaceholder={t("agentManager.dialog.searchBranches")}
+                  loadingLabel={t("agentManager.import.loadingBranches")}
+                  emptyLabel={t("agentManager.import.noMatchingBranches")}
+                  defaultLabel={t("agentManager.dialog.branchBadge.default")}
+                  remoteLabel={t("agentManager.dialog.branchBadge.remote")}
+                />
               </Popover>
             </div>
           </div>

packages/kilo-vscode/webview-ui/agent-manager/BranchSelect.tsx

@@ -0,0 +1,128 @@
+// Reusable branch selector: search input + scrollable list with keyboard navigation
+
+import { Component, For, Show } from "solid-js"
+import type { BranchInfo } from "../src/types/messages"
+import { Icon } from "@kilocode/kilo-ui/icon"
+import { Spinner } from "@kilocode/kilo-ui/spinner"
+import { formatRelativeDate } from "../src/utils/date"
+
+export interface AutoOption {
+  label: string
+  hint?: string
+  active: boolean
+  highlighted?: boolean
+  onSelect: () => void
+}
+
+export interface BranchSelectProps {
+  branches: BranchInfo[]
+  loading?: boolean
+  search: string
+  onSearch: (value: string) => void
+  onSelect: (branch: BranchInfo) => void
+  onSearchKeyDown?: (event: KeyboardEvent) => void
+  selected?: string
+  highlighted?: number
+  onHighlight?: (index: number) => void
+  defaultName?: string
+  searchPlaceholder: string
+  loadingLabel?: string
+  emptyLabel: string
+  defaultLabel: string
+  remoteLabel: string
+  autoOption?: AutoOption
+}
+
+export const BranchSelect: Component<BranchSelectProps> = (props) => {
+  const isDefault = (branch: BranchInfo) => {
+    if (props.defaultName) return branch.name === props.defaultName
+    return branch.isDefault
+  }
+
+  return (
+    <>
+      <div class="am-dropdown-search">
+        <Icon name="magnifying-glass" size="small" />
+        <input
+          class="am-dropdown-search-input"
+          type="text"
+          placeholder={props.searchPlaceholder}
+          value={props.search}
+          autofocus
+          onInput={(e) => props.onSearch(e.currentTarget.value)}
+          onKeyDown={(e) => props.onSearchKeyDown?.(e)}
+        />
+      </div>
+      <div class="am-dropdown-list">
+        <Show when={props.autoOption}>
+          {(opt) => (
+            <button
+              class="am-branch-item"
+              classList={{
+                "am-branch-item-active": opt().active,
+                "am-branch-item-highlighted": opt().highlighted,
+              }}
+              data-index="auto"
+              onClick={() => opt().onSelect()}
+              type="button"
+            >
+              <span class="am-branch-item-left">
+                <Icon name="branch" size="small" />
+                <span class="am-branch-item-name">{opt().label}</span>
+              </span>
+              <Show when={opt().hint}>
+                <span class="am-branch-hint">{opt().hint}</span>
+              </Show>
+            </button>
+          )}
+        </Show>
+        <Show
+          when={props.branches.length > 0}
+          fallback={
+            <Show when={!props.autoOption}>
+              <div class="am-dropdown-empty">
+                {props.loading ? (props.loadingLabel ?? props.emptyLabel) : props.emptyLabel}
+              </div>
+            </Show>
+          }
+        >
+          <For each={props.branches}>
+            {(branch, index) => (
+              <button
+                class="am-branch-item"
+                classList={{
+                  "am-branch-item-active": props.selected === branch.name,
+                  "am-branch-item-highlighted": props.highlighted === index(),
+                }}
+                data-index={index()}
+                onClick={() => props.onSelect(branch)}
+                onMouseEnter={() => props.onHighlight?.(index())}
+                type="button"
+              >
+                <span class="am-branch-item-left">
+                  <Icon name="branch" size="small" />
+                  <span class="am-branch-item-name">{branch.name}</span>
+                  <Show when={isDefault(branch)}>
+                    <span class="am-branch-badge">{props.defaultLabel}</span>
+                  </Show>
+                  <Show when={!branch.isLocal && branch.isRemote}>
+                    <span class="am-branch-badge am-branch-badge-remote">{props.remoteLabel}</span>
+                  </Show>
+                </span>
+                <Show when={branch.lastCommitDate}>
+                  <span class="am-branch-item-time">{formatRelativeDate(branch.lastCommitDate!)}</span>
+                </Show>
+              </button>
+            )}
+          </For>
+        </Show>
+        <Show when={props.loading && props.branches.length === 0 && !props.autoOption}>
+          <div class="am-dropdown-empty">
+            <Spinner class="am-setup-spinner" />
+            <span>{props.loadingLabel}</span>
+          </div>
+        </Show>
+      </div>
+    </>
+  )
+}

packages/kilo-vscode/webview-ui/agent-manager/agent-manager.css

@@ -3132,3 +3132,19 @@ button.am-section-toggle:hover .am-section-label {
 .am-file-tree-summary-dels {
   color: var(--syntax-diff-delete, #da3319);
 }
+
+/* ============ Default base branch picker dialog ============ */
+
+.am-default-base-branch {
+  min-width: 360px;
+}
+
+.am-default-base-branch .am-dropdown-list {
+  max-height: 320px;
+}
+
+.am-branch-hint {
+  margin-left: auto;
+  color: var(--text-weaker);
+  font-size: 11px;
+}

packages/kilo-vscode/webview-ui/agent-manager/i18n/ar.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "انقر مرتين لإعادة التسمية",
   "agentManager.worktree.versions": "{{count}} نسخ",
   "agentManager.worktree.advancedOptions": "خيارات Worktree متقدمة",
+  "agentManager.worktree.defaultBaseBranch": "الفرع الأساسي الافتراضي",
+  "agentManager.worktree.defaultBaseBranchAuto": "اكتشاف تلقائي",
   "agentManager.hoverCard.branch": "الفرع",
   "agentManager.hoverCard.base": "الأساس",
   "agentManager.hoverCard.sessions": "الجلسات",

packages/kilo-vscode/webview-ui/agent-manager/i18n/br.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "Clique duplo para renomear",
   "agentManager.worktree.versions": "{{count}} versões",
   "agentManager.worktree.advancedOptions": "Opções avançadas de Worktree",
+  "agentManager.worktree.defaultBaseBranch": "Branch base padrão",
+  "agentManager.worktree.defaultBaseBranchAuto": "Detecção automática",
   "agentManager.hoverCard.branch": "BRANCH",
   "agentManager.hoverCard.base": "Base",
   "agentManager.hoverCard.sessions": "Sessões",

packages/kilo-vscode/webview-ui/agent-manager/i18n/bs.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "Dvostruki klik za preimenovanje",
   "agentManager.worktree.versions": "{{count}} verzija",
   "agentManager.worktree.advancedOptions": "Napredne opcije Worktree-a",
+  "agentManager.worktree.defaultBaseBranch": "Zadana bazna grana",
+  "agentManager.worktree.defaultBaseBranchAuto": "Automatsko otkrivanje",
   "agentManager.hoverCard.branch": "BRANCH",
   "agentManager.hoverCard.base": "Baza",
   "agentManager.hoverCard.sessions": "Sesije",

packages/kilo-vscode/webview-ui/agent-manager/i18n/da.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "Dobbeltklik for at omdøbe",
   "agentManager.worktree.versions": "{{count}} versioner",
   "agentManager.worktree.advancedOptions": "Avancerede Worktree-indstillinger",
+  "agentManager.worktree.defaultBaseBranch": "Standard basisgren",
+  "agentManager.worktree.defaultBaseBranchAuto": "Automatisk registrering",
   "agentManager.hoverCard.branch": "BRANCH",
   "agentManager.hoverCard.base": "Base",
   "agentManager.hoverCard.sessions": "Sessioner",

packages/kilo-vscode/webview-ui/agent-manager/i18n/de.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "Doppelklick zum Umbenennen",
   "agentManager.worktree.versions": "{{count}} Versionen",
   "agentManager.worktree.advancedOptions": "Erweiterte Worktree-Optionen",
+  "agentManager.worktree.defaultBaseBranch": "Standard-Basiszweig",
+  "agentManager.worktree.defaultBaseBranchAuto": "Automatisch erkennen",
   "agentManager.hoverCard.branch": "BRANCH",
   "agentManager.hoverCard.base": "Basis",
   "agentManager.hoverCard.sessions": "Sitzungen",

packages/kilo-vscode/webview-ui/agent-manager/i18n/en.ts

@@ -15,6 +15,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "Double-click to rename",
   "agentManager.worktree.versions": "{{count}} versions",
   "agentManager.worktree.advancedOptions": "Advanced worktree options",
+  "agentManager.worktree.defaultBaseBranch": "Default Base Branch",
+  "agentManager.worktree.defaultBaseBranchAuto": "Auto-detect",
 
   "agentManager.hoverCard.branch": "BRANCH",
   "agentManager.hoverCard.base": "Base",
@@ -37,7 +39,6 @@ export const dict = {
 
   "agentManager.setup.failed": "Workspace setup failed",
   "agentManager.setup.settingUp": "Setting up workspace",
-
   "agentManager.shortcuts.title": "Keyboard Shortcuts",
   "agentManager.shortcuts.category.sidebar": "Sidebar",
   "agentManager.shortcuts.category.tabs": "Tabs",

packages/kilo-vscode/webview-ui/agent-manager/i18n/es.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "Doble clic para renombrar",
   "agentManager.worktree.versions": "{{count}} versiones",
   "agentManager.worktree.advancedOptions": "Opciones avanzadas de Worktree",
+  "agentManager.worktree.defaultBaseBranch": "Rama base predeterminada",
+  "agentManager.worktree.defaultBaseBranchAuto": "Detección automática",
   "agentManager.hoverCard.branch": "BRANCH",
   "agentManager.hoverCard.base": "Base",
   "agentManager.hoverCard.sessions": "Sesiones",

packages/kilo-vscode/webview-ui/agent-manager/i18n/fr.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "Double-cliquez pour renommer",
   "agentManager.worktree.versions": "{{count}} versions",
   "agentManager.worktree.advancedOptions": "Options avancées du Worktree",
+  "agentManager.worktree.defaultBaseBranch": "Branche de base par défaut",
+  "agentManager.worktree.defaultBaseBranchAuto": "Détection automatique",
   "agentManager.hoverCard.branch": "BRANCHE",
   "agentManager.hoverCard.base": "Base",
   "agentManager.hoverCard.sessions": "Sessions",

packages/kilo-vscode/webview-ui/agent-manager/i18n/ja.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "ダブルクリックで名前を変更",
   "agentManager.worktree.versions": "{{count}}バージョン",
   "agentManager.worktree.advancedOptions": "Worktreeの詳細オプション",
+  "agentManager.worktree.defaultBaseBranch": "デフォルトベースブランチ",
+  "agentManager.worktree.defaultBaseBranchAuto": "自動検出",
   "agentManager.hoverCard.branch": "ブランチ",
   "agentManager.hoverCard.base": "ベース",
   "agentManager.hoverCard.sessions": "セッション",

packages/kilo-vscode/webview-ui/agent-manager/i18n/ko.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "더블 클릭하여 이름 변경",
   "agentManager.worktree.versions": "{{count}}개 버전",
   "agentManager.worktree.advancedOptions": "Worktree 고급 옵션",
+  "agentManager.worktree.defaultBaseBranch": "기본 베이스 브랜치",
+  "agentManager.worktree.defaultBaseBranchAuto": "자동 감지",
   "agentManager.hoverCard.branch": "브랜치",
   "agentManager.hoverCard.base": "베이스",
   "agentManager.hoverCard.sessions": "세션",

packages/kilo-vscode/webview-ui/agent-manager/i18n/no.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "Dobbeltklikk for å gi nytt navn",
   "agentManager.worktree.versions": "{{count}} versjoner",
   "agentManager.worktree.advancedOptions": "Avanserte Worktree-alternativer",
+  "agentManager.worktree.defaultBaseBranch": "Standard basisgren",
+  "agentManager.worktree.defaultBaseBranchAuto": "Automatisk gjenkjenning",
   "agentManager.hoverCard.branch": "BRANCH",
   "agentManager.hoverCard.base": "Base",
   "agentManager.hoverCard.sessions": "Økter",

packages/kilo-vscode/webview-ui/agent-manager/i18n/pl.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "Kliknij dwukrotnie, aby zmienić nazwę",
   "agentManager.worktree.versions": "{{count}} wersji",
   "agentManager.worktree.advancedOptions": "Zaawansowane opcje Worktree",
+  "agentManager.worktree.defaultBaseBranch": "Domyślna gałąź bazowa",
+  "agentManager.worktree.defaultBaseBranchAuto": "Automatyczne wykrywanie",
   "agentManager.hoverCard.branch": "BRANCH",
   "agentManager.hoverCard.base": "Baza",
   "agentManager.hoverCard.sessions": "Sesje",

packages/kilo-vscode/webview-ui/agent-manager/i18n/ru.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "Двойной клик для переименования",
   "agentManager.worktree.versions": "{{count}} версий",
   "agentManager.worktree.advancedOptions": "Расширенные настройки Worktree",
+  "agentManager.worktree.defaultBaseBranch": "Базовая ветка по умолчанию",
+  "agentManager.worktree.defaultBaseBranchAuto": "Автоопределение",
   "agentManager.hoverCard.branch": "ВЕТКА",
   "agentManager.hoverCard.base": "Основа",
   "agentManager.hoverCard.sessions": "Сессии",

packages/kilo-vscode/webview-ui/agent-manager/i18n/th.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "ดับเบิลคลิกเพื่อเปลี่ยนชื่อ",
   "agentManager.worktree.versions": "{{count}} เวอร์ชัน",
   "agentManager.worktree.advancedOptions": "ตัวเลือก Worktree ขั้นสูง",
+  "agentManager.worktree.defaultBaseBranch": "สาขาฐานเริ่มต้น",
+  "agentManager.worktree.defaultBaseBranchAuto": "ตรวจจับอัตโนมัติ",
   "agentManager.hoverCard.branch": "BRANCH",
   "agentManager.hoverCard.base": "ฐาน",
   "agentManager.hoverCard.sessions": "เซสชัน",

packages/kilo-vscode/webview-ui/agent-manager/i18n/zh.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "双击重命名",
   "agentManager.worktree.versions": "{{count}} 个版本",
   "agentManager.worktree.advancedOptions": "Worktree 高级选项",
+  "agentManager.worktree.defaultBaseBranch": "默认基础分支",
+  "agentManager.worktree.defaultBaseBranchAuto": "自动检测",
   "agentManager.hoverCard.branch": "分支",
   "agentManager.hoverCard.base": "基础",
   "agentManager.hoverCard.sessions": "会话",

packages/kilo-vscode/webview-ui/agent-manager/i18n/zht.ts

@@ -14,6 +14,8 @@ export const dict = {
   "agentManager.worktree.doubleClickRename": "按兩下以重新命名",
   "agentManager.worktree.versions": "{{count}} 個版本",
   "agentManager.worktree.advancedOptions": "Worktree 進階選項",
+  "agentManager.worktree.defaultBaseBranch": "預設基礎分支",
+  "agentManager.worktree.defaultBaseBranchAuto": "自動偵測",
   "agentManager.hoverCard.branch": "分支",
   "agentManager.hoverCard.base": "基底",
   "agentManager.hoverCard.sessions": "工作階段",

packages/kilo-vscode/webview-ui/src/types/messages.ts

@@ -626,6 +626,7 @@ export interface AgentManagerSessionMetaMessage {
 export interface AgentManagerRepoInfoMessage {
   type: "agentManager.repoInfo"
   branch: string
+  defaultBranch?: string
 }
 
 // Agent Manager worktree setup progress
@@ -674,6 +675,7 @@ export interface AgentManagerStateMessage {
   sessionsCollapsed?: boolean
   reviewDiffStyle?: "unified" | "split"
   isGitRepo?: boolean
+  defaultBaseBranch?: string
 }
 
 // Resolved keybindings for agent manager actions
@@ -703,6 +705,7 @@ export interface BranchInfo {
   isRemote: boolean
   isDefault: boolean
   lastCommitDate?: string
+  isCheckedOut?: boolean
 }
 
 export interface AgentManagerBranchesMessage {
@@ -1450,6 +1453,12 @@ export interface EnhancePromptRequest {
   requestId: string
 }
 
+// Set default base branch (webview → extension)
+export interface SetDefaultBaseBranchRequest {
+  type: "agentManager.setDefaultBaseBranch"
+  branch?: string
+}
+
 export type WebviewMessage =
   | SendMessageRequest
   | AbortRequest
@@ -1532,6 +1541,7 @@ export type WebviewMessage =
   // legacy-migration end
   | ApplyWorktreeDiffMessage
   | EnhancePromptRequest
+  | SetDefaultBaseBranchRequest
 
 // ============================================
 // VS Code API type