feat(ai): rename conversations + reasoning block

__tests__/components/AIAssistant.test.tsx

@@ -34,6 +34,7 @@ function mockChat(overrides: Partial<ReturnType<typeof useAIChat>> = {}) {
     newConversation: jest.fn().mockResolvedValue(undefined),
     loadConversation: jest.fn().mockResolvedValue(undefined),
     removeConversation: jest.fn().mockResolvedValue(undefined),
+    renameConversation: jest.fn().mockResolvedValue(undefined),
     ...overrides,
   };
   mockUseAIChat.mockReturnValue(base);
@@ -187,5 +188,33 @@ describe("AIAssistantScreen", () => {
       fireEvent.press(getByLabelText("Delete conversation"));
       expect(chat.removeConversation).toHaveBeenCalledWith("c1");
     });
+
+    it("renames a conversation via the dialog", () => {
+      const chat = mockChat({
+        serverBacked: true,
+        conversations: [{ id: "c1", title: "Old name" }],
+      });
+      const { getByLabelText, getByRole } = renderScreen();
+      fireEvent.press(getByLabelText("Conversation history"));
+      fireEvent.press(getByLabelText("Rename conversation"));
+      // The dialog opens prefilled with the current title.
+      const input = getByLabelText("Conversation title");
+      fireEvent.changeText(input, "New name");
+      fireEvent.press(getByRole("button", { name: "Save" }));
+      expect(chat.renameConversation).toHaveBeenCalledWith("c1", "New name");
+    });
+  });
+
+  it("renders a reasoning block when the message has reasoning", () => {
+    mockChat({
+      messages: [
+        { role: "user", content: "why?" },
+        { role: "assistant", content: "Because.", reasoning: "Considered the trade-offs." },
+      ],
+    });
+    const { getByText, getByLabelText } = renderScreen();
+    expect(getByText("Reasoning")).toBeTruthy();
+    fireEvent.press(getByLabelText("Reasoning"));
+    expect(getByText("Considered the trade-offs.")).toBeTruthy();
   });
 });

__tests__/components/Reasoning.test.tsx

@@ -0,0 +1,20 @@
+import React from "react";
+import { render, fireEvent } from "@testing-library/react-native";
+import { Reasoning } from "~/components/ui/Reasoning";
+
+describe("Reasoning", () => {
+  it("renders nothing when reasoning is empty", () => {
+    expect(render(<Reasoning reasoning="" />).toJSON()).toBeNull();
+    expect(render(<Reasoning reasoning="   " />).toJSON()).toBeNull();
+  });
+
+  it("is collapsed by default and expands on tap", () => {
+    const { getByLabelText, getByText, queryByText } = render(
+      <Reasoning reasoning="First I considered the options." />,
+    );
+    expect(getByText("Reasoning")).toBeTruthy();
+    expect(queryByText("First I considered the options.")).toBeNull();
+    fireEvent.press(getByLabelText("Reasoning"));
+    expect(getByText("First I considered the options.")).toBeTruthy();
+  });
+});

__tests__/lib/ai-chat.test.ts

@@ -83,6 +83,19 @@ describe("parseAiSdkStream", () => {
     expect(parseAiSdkStream(raw).toolCalls).toEqual(["list_objects", "query_data"]);
   });
 
+  it("accumulates reasoning-delta events into the reasoning field", () => {
+    const raw = [
+      `data: {"type":"reasoning-start","id":"r0"}`,
+      `data: {"type":"reasoning-delta","id":"r0","delta":"Let me "}`,
+      `data: {"type":"reasoning-delta","id":"r0","delta":"think."}`,
+      `data: {"type":"reasoning-end","id":"r0"}`,
+      `data: {"type":"text-delta","delta":"Answer."}`,
+    ].join("\n");
+    const parsed = parseAiSdkStream(raw);
+    expect(parsed.reasoning).toBe("Let me think.");
+    expect(parsed.text).toBe("Answer.");
+  });
+
   it("captures structured tool invocations (input, output, state) by toolCallId", () => {
     const raw = [
       `data: {"type":"tool-input-available","toolCallId":"tc1","toolName":"query_data","input":{"request":"count"}}`,
@@ -109,7 +122,7 @@ describe("parseAiSdkStream", () => {
   });
 
   it("returns an empty result for empty input", () => {
-    expect(parseAiSdkStream("")).toEqual({ text: "", toolCalls: [], tools: [] });
+    expect(parseAiSdkStream("")).toEqual({ text: "", reasoning: "", toolCalls: [], tools: [] });
   });
 });
 

__tests__/stores/ai-chat-store.test.ts

@@ -8,6 +8,7 @@ jest.mock("~/lib/ai-conversations", () => ({
   getConversation: jest.fn(),
   deleteConversation: jest.fn(),
   addMessage: jest.fn(),
+  renameConversation: jest.fn(),
 }));
 import { streamAiChat } from "~/lib/ai-chat";
 import * as conv from "~/lib/ai-conversations";
@@ -206,5 +207,20 @@ describe("ai-chat-store", () => {
       expect(get().conversationId).toBeNull();
       expect(get().messages).toEqual([]);
     });
+
+    it("renameConversation optimistically updates the list then PATCHes", async () => {
+      useAIChatStore.setState({ conversations: [{ id: "c5", title: "Old" }] });
+      (conv.renameConversation as jest.Mock).mockResolvedValue(undefined);
+      await get().renameConversation("c5", "  Brand New  ");
+      expect(get().conversations).toEqual([{ id: "c5", title: "Brand New" }]);
+      expect(conv.renameConversation).toHaveBeenCalledWith("c5", "Brand New");
+    });
+
+    it("renameConversation ignores a blank title", async () => {
+      useAIChatStore.setState({ conversations: [{ id: "c5", title: "Old" }] });
+      await get().renameConversation("c5", "   ");
+      expect(conv.renameConversation).not.toHaveBeenCalled();
+      expect(get().conversations).toEqual([{ id: "c5", title: "Old" }]);
+    });
   });
 });

app/ai.tsx

@@ -21,12 +21,16 @@ import {
   Square,
   SquarePen,
   MessagesSquare,
+  Pencil,
 } from "lucide-react-native";
 import { ScreenHeader } from "~/components/common/ScreenHeader";
 import { EmptyState } from "~/components/common/EmptyState";
 import { BottomSheet } from "~/components/ui/BottomSheet";
+import { Dialog } from "~/components/ui/Dialog";
+import { Button } from "~/components/ui/Button";
 import { MarkdownText } from "~/components/ui/MarkdownText";
 import { ToolInvocations } from "~/components/ui/ToolInvocations";
+import { Reasoning } from "~/components/ui/Reasoning";
 import { cn } from "~/lib/utils";
 import { useAIChat, type AIChatMessage } from "~/hooks/useAIChat";
 
@@ -71,7 +75,8 @@ function MessageBubble({ message }: { message: AIChatMessage }) {
 
   return (
     <View className={cn("mb-3 max-w-[85%]", isUser ? "self-end" : "self-start")}>
-      {/* Structured tool activity (assistant only) */}
+      {/* Reasoning trace, then tool activity (assistant only) */}
+      {!isUser && message.reasoning ? <Reasoning reasoning={message.reasoning} /> : null}
       {!isUser && message.tools && message.tools.length > 0 && (
         <ToolInvocations tools={message.tools} />
       )}
@@ -118,9 +123,11 @@ export default function AIAssistantScreen() {
     newConversation,
     loadConversation,
     removeConversation,
+    renameConversation,
   } = useAIChat();
   const [draft, setDraft] = useState("");
   const [drawerOpen, setDrawerOpen] = useState(false);
+  const [renaming, setRenaming] = useState<{ id: string; title: string } | null>(null);
   const scrollRef = useRef<ScrollView>(null);
 
   // Probe the server + restore the last conversation on first mount.
@@ -225,6 +232,17 @@ export default function AIAssistantScreen() {
                   {c.title ?? "New conversation"}
                 </Text>
               </Pressable>
+              <Pressable
+                onPress={() => {
+                  setDrawerOpen(false);
+                  setRenaming({ id: c.id, title: c.title ?? "" });
+                }}
+                accessibilityRole="button"
+                accessibilityLabel="Rename conversation"
+                className="h-9 w-9 items-center justify-center rounded-lg active:bg-muted"
+              >
+                <Pencil size={15} color="#94a3b8" />
+              </Pressable>
               <Pressable
                 onPress={() => void removeConversation(c.id)}
                 accessibilityRole="button"
@@ -238,6 +256,46 @@ export default function AIAssistantScreen() {
         )}
       </BottomSheet>
 
+      {/* Rename dialog */}
+      <Dialog
+        open={renaming !== null}
+        onOpenChange={(o) => !o && setRenaming(null)}
+        title="Rename conversation"
+      >
+        {renaming && (
+          <View className="gap-3">
+            <TextInput
+              className="rounded-lg border border-input bg-background px-3 py-2.5 text-base text-foreground"
+              value={renaming.title}
+              onChangeText={(t) => setRenaming({ ...renaming, title: t })}
+              placeholder="Conversation title"
+              placeholderTextColor="#9ca3af"
+              autoFocus
+              onSubmitEditing={() => {
+                const r = renaming;
+                setRenaming(null);
+                void renameConversation(r.id, r.title);
+              }}
+              accessibilityLabel="Conversation title"
+            />
+            <View className="flex-row justify-end gap-2">
+              <Button variant="outline" onPress={() => setRenaming(null)}>
+                Cancel
+              </Button>
+              <Button
+                onPress={() => {
+                  const r = renaming;
+                  setRenaming(null);
+                  void renameConversation(r.id, r.title);
+                }}
+              >
+                Save
+              </Button>
+            </View>
+          </View>
+        )}
+      </Dialog>
+
       <KeyboardAvoidingView
         className="flex-1"
         behavior={Platform.OS === "ios" ? "padding" : undefined}

components/ui/Reasoning.tsx

@@ -0,0 +1,48 @@
+import { useState } from "react";
+import { View, Text, Pressable } from "react-native";
+import { ChevronRight, ChevronDown, Brain } from "lucide-react-native";
+import { cn } from "~/lib/utils";
+
+/**
+ * Collapsible "thinking" block for a model's reasoning trace — a React Native
+ * take on Vercel AI Elements' `Reasoning` component (web/DOM-only). Collapsed
+ * by default (reasoning is secondary to the answer); tap to expand.
+ *
+ * Only renders when the agent actually streamed reasoning; the current
+ * ObjectStack agent does not, so this stays invisible until a reasoning-capable
+ * model is wired up server-side.
+ */
+export function Reasoning({
+  reasoning,
+  className,
+}: {
+  reasoning: string;
+  className?: string;
+}) {
+  const [open, setOpen] = useState(false);
+  if (!reasoning || reasoning.trim() === "") return null;
+  return (
+    <View className={cn("mb-1 overflow-hidden rounded-lg border border-border bg-muted/40", className)}>
+      <Pressable
+        className="flex-row items-center gap-2 px-2.5 py-2 active:bg-muted"
+        onPress={() => setOpen((o) => !o)}
+        accessibilityRole="button"
+        accessibilityLabel="Reasoning"
+        accessibilityState={{ expanded: open }}
+      >
+        <Brain size={13} color="#64748b" />
+        <Text className="flex-1 text-xs font-medium text-muted-foreground">Reasoning</Text>
+        {open ? (
+          <ChevronDown size={14} color="#94a3b8" />
+        ) : (
+          <ChevronRight size={14} color="#94a3b8" />
+        )}
+      </Pressable>
+      {open && (
+        <View className="border-t border-border px-2.5 py-2">
+          <Text className="text-xs leading-5 text-muted-foreground">{reasoning.trim()}</Text>
+        </View>
+      )}
+    </View>
+  );
+}

hooks/useAIChat.ts

@@ -29,6 +29,8 @@ export interface UseAIChatResult {
   loadConversation: (id: string) => Promise<void>;
   /** Delete a saved conversation. */
   removeConversation: (id: string) => Promise<void>;
+  /** Rename a saved conversation. */
+  renameConversation: (id: string, title: string) => Promise<void>;
 }
 
 /**
@@ -53,6 +55,7 @@ export function useAIChat(): UseAIChatResult {
   const newConversation = useAIChatStore((s) => s.newConversation);
   const loadConversation = useAIChatStore((s) => s.loadConversation);
   const removeConversation = useAIChatStore((s) => s.removeConversation);
+  const renameConversation = useAIChatStore((s) => s.renameConversation);
   return {
     messages,
     isLoading,
@@ -68,5 +71,6 @@ export function useAIChat(): UseAIChatResult {
     newConversation,
     loadConversation,
     removeConversation,
+    renameConversation,
   };
 }

lib/ai-chat.ts

@@ -43,6 +43,8 @@ export interface ToolInvocation {
 export interface ParsedAiStream {
   /** Concatenated assistant text (from `text-delta` / `text` events). */
   text: string;
+  /** Concatenated reasoning/thinking text (from `reasoning-delta` events). */
+  reasoning: string;
   /** Names of tools the agent invoked (back-compat; see `tools` for detail). */
   toolCalls: string[];
   /** Structured tool invocations (name + input + output + state). */
@@ -75,6 +77,12 @@ function applyEvent(event: Record<string, unknown>, acc: ParsedAiStream): void {
       // Some servers emit a single full-text event instead of deltas.
       if (typeof event.text === "string") acc.text += event.text;
       break;
+    case "reasoning-delta":
+      if (typeof event.delta === "string") acc.reasoning += event.delta;
+      break;
+    case "reasoning":
+      if (typeof event.text === "string") acc.reasoning += event.text;
+      break;
     case "tool-input-available":
       if (typeof event.toolName === "string") {
         acc.toolCalls.push(event.toolName);
@@ -124,7 +132,7 @@ function parseEventLine(line: string): Record<string, unknown> | null {
 }
 
 export function parseAiSdkStream(raw: string): ParsedAiStream {
-  const result: ParsedAiStream = { text: "", toolCalls: [], tools: [] };
+  const result: ParsedAiStream = { text: "", reasoning: "", toolCalls: [], tools: [] };
   if (!raw) return result;
   for (const line of raw.split("\n")) {
     const event = parseEventLine(line);
@@ -188,8 +196,8 @@ function errorMessageFromBody(raw: string, status: number): string {
 
 export interface StreamAiChatOptions {
   signal?: AbortSignal;
-  /** Called as text accumulates, with the full reply so far + tools seen. */
-  onUpdate?: (text: string, tools: ToolInvocation[]) => void;
+  /** Called as text accumulates, with the full reply so far + tools + reasoning. */
+  onUpdate?: (text: string, tools: ToolInvocation[], reasoning: string) => void;
   /** Bind the turn to a server conversation (for server-side persistence). */
   conversationId?: string;
 }
@@ -232,24 +240,25 @@ export async function streamAiChat(
     // Streaming not supported in this runtime — read it whole.
     const raw = await res.text();
     const parsed = parseAiSdkStream(raw);
-    onUpdate?.(parsed.text, parsed.tools);
+    onUpdate?.(parsed.text, parsed.tools, parsed.reasoning);
     return parsed;
   }
 
   const reader = body.getReader();
   const decoder = new TextDecoder();
-  const acc: ParsedAiStream = { text: "", toolCalls: [], tools: [] };
+  const acc: ParsedAiStream = { text: "", reasoning: "", toolCalls: [], tools: [] };
   let buffer = "";
 
-  // A cheap signature so onUpdate fires on text deltas, new tool calls, and a
-  // tool's state flipping to `done` (output arriving).
-  const sig = () => `${acc.text.length}|${acc.tools.map((t) => t.id + t.state).join(",")}`;
+  // A cheap signature so onUpdate fires on text/reasoning deltas, new tool
+  // calls, and a tool's state flipping to `done` (output arriving).
+  const sig = () =>
+    `${acc.text.length}|${acc.reasoning.length}|${acc.tools.map((t) => t.id + t.state).join(",")}`;
   const drainLine = (line: string) => {
     const event = parseEventLine(line);
     if (!event) return;
     const before = sig();
     applyEvent(event, acc);
-    if (sig() !== before) onUpdate?.(acc.text, acc.tools);
+    if (sig() !== before) onUpdate?.(acc.text, acc.tools, acc.reasoning);
   };
 
   try {