SoulKyu · Oct 5, 2026
diff --git a/AGENTS.md b/AGENTS.md
@@ -39,7 +39,7 @@ app/api/
   sessions/[id]/state/route.ts     GET live wrapper state while running
   sessions/[id]/auto-name/route.ts POST generate a session title
   sessions/search/route.ts         GET session search
-  agent/new/route.ts               POST { cwd, type: prompt|ensure_session (start only), message?, toolNames?, provider?, modelId?, thinkingLevel? }
+  agent/new/route.ts               POST { cwd, type: prompt|ensure_session (start only), message?, toolNames?, provider?, modelId?, thinkingLevel?, agentProfile? }
   agent/[id]/route.ts              GET state | POST any command
   agent/[id]/events/route.ts       GET SSE stream
   agent/running/route.ts           GET running session ids

diff --git a/app/api/agent/new/route.ts b/app/api/agent/new/route.ts
@@ -45,7 +45,10 @@ export async function POST(req: Request) {
     }
 
     // Use a one-time key so startRpcSession's lock doesn't conflict with real session ids
-    const { provider, modelId, toolNames, thinkingLevel, ...promptCommand } = command as { provider?: string; modelId?: string; toolNames?: string[]; thinkingLevel?: unknown; [key: string]: unknown };
+    const { provider, modelId, toolNames, thinkingLevel, agentProfile, ...promptCommand } = command as { provider?: string; modelId?: string; toolNames?: string[]; thinkingLevel?: unknown; agentProfile?: unknown; [key: string]: unknown };
+    if (agentProfile !== undefined && (typeof agentProfile !== "string" || !agentProfile.trim())) {
+      throw new Error("agentProfile must be a non-empty string");
+    }
     if ((provider && !modelId) || (!provider && modelId)) {
       throw new Error("provider and modelId must be provided together");
     }
@@ -56,7 +59,8 @@ export async function POST(req: Request) {
     // requests in the same millisecond, merging two new sessions into one.
     const tempKey = `__new__${randomUUID()}`;
     const { session, realSessionId } = await startRpcSession(tempKey, "", cwd, {
-      ...(toolNames ? { toolNames } : {}),
+      // A profile fixes its own tools, so a tool preset sent alongside it is ignored.
+      ...(agentProfile ? { agentProfile } : toolNames ? { toolNames } : {}),
       ...(provider && modelId ? { initialModel: { provider, modelId } } : {}),
       ...(explicitThinkingLevel ? { thinkingLevel: explicitThinkingLevel } : {}),
     });

diff --git a/app/api/sessions/[id]/route.ts b/app/api/sessions/[id]/route.ts
@@ -22,7 +22,7 @@ import { computeSessionStats } from "@/lib/session-stats";
 import { startServerPerf } from "@/lib/perf";
 import { computeSessionRevision } from "@/lib/session-revision";
 import type { SessionEntry } from "@/lib/types";
-import { readSubagentRun, readSubagentSessionResources, SUBAGENT_META_TYPE } from "@/lib/subagents";
+import { readSessionAgentProfile, readSubagentRun, readSubagentSessionResources, SUBAGENT_META_TYPE } from "@/lib/subagents";
 import { readSessionToolSelection } from "@/lib/session-tool-selection";
 import { jsonResponse } from "@/lib/json-response";
 
@@ -108,6 +108,7 @@ export async function GET(
       : null;
     const toolNames = readSubagentSessionResources(entries as never)?.tools
       ?? readSessionToolSelection(entries as never);
+    const agentProfile = readSessionAgentProfile(entries as never);
     const info = header ? (await attachSessionProjectInfo([{
       path: filePath,
       id: header.id,
@@ -145,6 +146,7 @@ export async function GET(
         stats,
         totalActiveMs,
         ...(toolNames !== undefined ? { toolNames } : {}),
+        ...(agentProfile ? { agentProfile } : {}),
         ...(wrapperRebuilt ? { wrapperRebuilt: true } : {}),
       },
     )) ?? jsonResponse(
@@ -161,6 +163,7 @@ export async function GET(
         stats,
         totalActiveMs,
         ...(toolNames !== undefined ? { toolNames } : {}),
+        ...(agentProfile ? { agentProfile } : {}),
         ...(wrapperRebuilt ? { wrapperRebuilt: true } : {}),
       },
     );

diff --git a/components/AgentProfileSelector.tsx b/components/AgentProfileSelector.tsx
@@ -0,0 +1,168 @@
+"use client";
+
+import { useEffect, useMemo, useRef, useState } from "react";
+import { useI18n } from "@/hooks/useI18n";
+
+interface ProfileOption {
+  name: string;
+  displayName: string;
+  description: string;
+}
+
+interface Props {
+  cwd?: string;
+  agentProfile: string | null;
+  /** Present only while the session can still pick its agent (a new, unsent session). */
+  onChange?: (profile: string | null) => void;
+  disabled?: boolean;
+  isMobile?: boolean;
+  showLabel?: boolean;
+}
+
+/** Enabled profiles, one per name: the API lists shadowed sources too, highest precedence last. */
+function uniqueEnabledProfiles(profiles: Array<ProfileOption & { enabled?: boolean }>): ProfileOption[] {
+  const byName = new Map<string, ProfileOption & { enabled?: boolean }>();
+  for (const profile of profiles) byName.set(profile.name.toLowerCase(), profile);
+  return [...byName.values()]
+    .filter((profile) => profile.enabled !== false)
+    .sort((a, b) => a.displayName.localeCompare(b.displayName));
+}
+
+export function AgentProfileSelector({ cwd, agentProfile, onChange, disabled, isMobile, showLabel = true }: Props) {
+  const { t } = useI18n();
+  const [open, setOpen] = useState(false);
+  const [query, setQuery] = useState("");
+  const [profiles, setProfiles] = useState<ProfileOption[] | null>(null);
+  const rootRef = useRef<HTMLDivElement>(null);
+  const editable = Boolean(onChange) && !disabled;
+
+  useEffect(() => {
+    if (!open || !cwd) return;
+    const controller = new AbortController();
+    void fetch(`/api/subagents/profiles?cwd=${encodeURIComponent(cwd)}`, { cache: "no-store", signal: controller.signal })
+      .then((response) => response.ok ? response.json() : { profiles: [] })
+      .then((body: { profiles?: Array<ProfileOption & { enabled?: boolean }> }) => setProfiles(uniqueEnabledProfiles(body.profiles ?? [])))
+      .catch(() => { if (!controller.signal.aborted) setProfiles([]); });
+    return () => controller.abort();
+  }, [open, cwd]);
+
+  useEffect(() => {
+    if (!open) return;
+    const close = (event: MouseEvent) => {
+      if (!rootRef.current?.contains(event.target as Node)) setOpen(false);
+    };
+    document.addEventListener("mousedown", close);
+    return () => document.removeEventListener("mousedown", close);
+  }, [open]);
+
+  const filtered = useMemo(() => {
+    const needle = query.trim().toLowerCase();
+    if (!profiles || !needle) return profiles ?? [];
+    return profiles.filter((profile) =>
+      profile.name.toLowerCase().includes(needle)
+      || profile.displayName.toLowerCase().includes(needle)
+      || profile.description.toLowerCase().includes(needle));
+  }, [profiles, query]);
+
+  // A session without a profile that can no longer pick one has nothing to show.
+  if (!agentProfile && !editable) return null;
+
+  const label = agentProfile ?? t("chat.defaultAgent");
+  const select = (profile: string | null) => {
+    setOpen(false);
+    setQuery("");
+    if (profile !== agentProfile) onChange?.(profile);
+  };
+  const rowStyle = (active: boolean) => ({
+    display: "flex", flexDirection: "column" as const, alignItems: "flex-start", gap: 2,
+    width: "100%", padding: "7px 12px",
+    background: active ? "var(--bg-selected)" : "none",
+    border: "none",
+    color: active ? "var(--text)" : "var(--text-muted)",
+    cursor: "pointer", fontSize: 12, textAlign: "left" as const,
+    fontWeight: active ? 600 : 400,
+  });
+
+  return (
+    <div ref={rootRef} style={{ position: "relative" }}>
+      <button
+        onClick={() => editable && setOpen((value) => !value)}
+        disabled={!editable}
+        title={editable ? `${t("chat.changeAgentProfile")}: ${label}` : t("chat.agentProfileFixed")}
+        aria-label={t("chat.agentProfile")}
+        style={{
+          display: "flex", alignItems: "center", justifyContent: "center", gap: 5,
+          padding: isMobile ? "0 6px" : "8px 12px",
+          height: 32,
+          background: open ? "var(--bg-hover)" : "none",
+          border: "none",
+          borderRadius: 9,
+          color: agentProfile ? "var(--accent)" : "var(--text-muted)",
+          cursor: editable ? "pointer" : "default",
+          fontSize: 12,
+        }}
+      >
+        <svg width="11" height="11" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round">
+          <circle cx="12" cy="8" r="4" />
+          <path d="M4 21v-1a6 6 0 0 1 6-6h4a6 6 0 0 1 6 6v1" />
+        </svg>
+        {showLabel && <span style={{ whiteSpace: "nowrap", maxWidth: 160, overflow: "hidden", textOverflow: "ellipsis" }}>{label}</span>}
+      </button>
+      {open && (
+        <div style={{
+          position: "absolute",
+          bottom: "calc(100% + 6px)",
+          right: isMobile ? undefined : 0,
+          left: isMobile ? 0 : undefined,
+          zIndex: 100, background: "var(--bg)", border: "1px solid var(--border)",
+          borderRadius: 8, boxShadow: "0 -4px 16px rgba(0,0,0,0.10)",
+          width: isMobile ? "min(320px, calc(100vw - 32px))" : 320,
+          display: "flex", flexDirection: "column",
+        }}>
+          <input
+            autoFocus
+            value={query}
+            onChange={(event) => setQuery(event.target.value)}
+            onKeyDown={(event) => {
+              if (event.key === "Escape") { event.stopPropagation(); setOpen(false); }
+              if (event.key === "Enter" && filtered.length > 0) select(filtered[0].name);
+            }}
+            placeholder={t("chat.searchAgents")}
+            aria-label={t("chat.searchAgents")}
+            style={{
+              margin: 8, padding: "6px 8px", fontSize: 12,
+              background: "var(--bg-panel)", color: "var(--text)",
+              border: "1px solid var(--border)", borderRadius: 6, outline: "none",
+            }}
+          />
+          <div style={{ maxHeight: 320, overflowY: "auto" }}>
+            {!query.trim() && (
+              <button onClick={() => select(null)} style={rowStyle(agentProfile === null)}>
+                {t("chat.defaultAgent")}
+              </button>
+            )}
+            {filtered.map((profile) => (
+              <button
+                key={profile.name}
+                onClick={() => select(profile.name)}
+                title={profile.description}
+                style={rowStyle(agentProfile === profile.name)}
+              >
+                <span>{profile.displayName}</span>
+                <span style={{
+                  fontSize: 11, color: "var(--text-dim)", fontWeight: 400,
+                  overflow: "hidden", textOverflow: "ellipsis", whiteSpace: "nowrap", width: "100%",
+                }}>
+                  {profile.description}
+                </span>
+              </button>
+            ))}
+            {profiles && filtered.length === 0 && (
+              <div style={{ padding: "7px 12px", fontSize: 12, color: "var(--text-dim)" }}>{t("chat.noAgentsFound")}</div>
+            )}
+          </div>
+        </div>
+      )}
+    </div>
+  );
+}
diff --git a/components/ChatInput.tsx b/components/ChatInput.tsx
@@ -31,6 +31,7 @@ import { useEnterSendMode } from "@/hooks/useEnterSendMode";
 import { useI18n } from "@/hooks/useI18n";
 import { useChatAppearance } from "@/hooks/useChatAppearance";
 import type { ToolPreset } from "@/lib/tool-presets";
+import { AgentProfileSelector } from "./AgentProfileSelector";
 import { SelectorRow } from "./SelectorRow";
 import { ModelSelector, type ModelSelectorOption } from "./ModelSelector";
 
@@ -71,6 +72,10 @@ interface Props {
   compactResult?: CompactResultInfo | null;
   toolPreset?: ToolPreset;
   onToolPresetChange?: (preset: ToolPreset) => void;
+  /** The agent profile the session runs as; null is the default agent. */
+  agentProfile?: string | null;
+  /** Present only while a new session can still choose its agent profile. */
+  onAgentProfileChange?: (profile: string | null) => void;
   thinkingLevel?: "auto" | "off" | "minimal" | "low" | "medium" | "high" | "xhigh" | "max";
   /** New session has not committed a thinking level; the button still shows the resolved default. */
   isAutoThinkingSelection?: boolean;
@@ -587,7 +592,7 @@ export function ModelScopeWarningBanner({ warnings }: { warnings?: string[] }) {
 export const ChatInput = forwardRef<ChatInputHandle, Props>(function ChatInput({
   onSend, onAbort, onSteer, onFollowUp, isStreaming, model, isAutoModelSelection, modelNames, modelList, modelError, modelScopeWarnings, onModelChange, modelSwitching,
   defaultModel, onSetDefaultModel,
-  onCompact, onAbortCompaction, isCompacting, compactError, compactResult, toolPreset, onToolPresetChange,
+  onCompact, onAbortCompaction, isCompacting, compactError, compactResult, toolPreset, onToolPresetChange, agentProfile = null, onAgentProfileChange,
   thinkingLevel, isAutoThinkingSelection = false, onThinkingLevelChange, availableThinkingLevels, thinkingLevelMap,
   savedDefaultThinkingLevel, onSetDefaultThinkingLevel,
   retryInfo, queuedMessages, inputHistory = [], onRecallQueue,
@@ -2568,6 +2573,15 @@ export const ChatInput = forwardRef<ChatInputHandle, Props>(function ChatInput({
                 )}
               </div>
             )}
+            {!isStreaming && (
+              <AgentProfileSelector
+                cwd={cwd ?? undefined}
+                agentProfile={agentProfile}
+                onChange={onAgentProfileChange}
+                isMobile={isMobile}
+                showLabel={!isMobile || controlsMenuOpen}
+              />
+            )}
             {!isStreaming && onToolPresetChange && (
               <div ref={toolDropdownRef} style={{ position: "relative" }}>
                 <button

diff --git a/components/ChatWindow.tsx b/components/ChatWindow.tsx
@@ -257,7 +257,7 @@ export function ChatWindow({ session, searchTarget, onSearchTargetHandled, initi
 
   const {
     loading, error, messages, activeToolResults, entryIds, historyCursor, hasEarlierMessages, streamState,
-    agentRunning, bashRunning, pendingBash, modelNames, modelList, modelError, modelScopeWarnings, modelThinkingLevels, modelThinkingLevelMaps, toolPreset, thinkingLevel,
+    agentRunning, bashRunning, pendingBash, modelNames, modelList, modelError, modelScopeWarnings, modelThinkingLevels, modelThinkingLevelMaps, toolPreset, agentProfile, thinkingLevel,
     retryInfo, contextUsage, forkingEntryId,
     isCompacting, compactError, compactResult, displayModel: displayModelValue, modelSwitching, sessionStats,
     slashCommands, slashCommandsLoading, queuedMessages,
@@ -276,7 +276,7 @@ export function ChatWindow({ session, searchTarget, onSearchTargetHandled, initi
     handleCompact, handleSteer, handleFollowUp, handlePromptWithStreamingBehavior, handleAbortCompaction,
     handleRecallQueue,
     handleBuiltinSlashCommand,
-    handleToolPresetChange, handleThinkingLevelChange, handleSetDefaultModel, handleSetDefaultThinkingLevel, loadSlashCommands, scrollUserMsgToTop,
+    handleToolPresetChange, handleAgentProfileChange, handleThinkingLevelChange, handleSetDefaultModel, handleSetDefaultThinkingLevel, loadSlashCommands, scrollUserMsgToTop,
     loadContext, activeLeafId, scrollToBottom, scrollToMessage,
   } = useAgentSession({
     session, sessionRunning, newSessionCwd, newSessionDraftKey, onAgentEnd: wrappedOnAgentEnd, onAttentionNeeded, onSessionCreated, onSessionForked,
@@ -870,7 +870,10 @@ export function ChatWindow({ session, searchTarget, onSearchTargetHandled, initi
       compactError={compactError}
       compactResult={compactResult}
       toolPreset={toolPreset}
-      onToolPresetChange={session || isNew ? handleToolPresetChange : undefined}
+      // An agent profile fixes the session's tools.
+      onToolPresetChange={(session || isNew) && !agentProfile ? handleToolPresetChange : undefined}
+      agentProfile={agentProfile}
+      onAgentProfileChange={isNew && messages.length === 0 ? handleAgentProfileChange : undefined}
       thinkingLevel={thinkingLevel}
       isAutoThinkingSelection={isAutoThinkingSelection}
       onThinkingLevelChange={session || isNew ? handleThinkingLevelChange : undefined}