diff --git a/src/main/db/connection.ts b/src/main/db/connection.ts
index 062569987..aa72c7929 100644
--- a/src/main/db/connection.ts
+++ b/src/main/db/connection.ts
@@ -3,6 +3,7 @@ import { join } from "node:path";
 import Database from "better-sqlite3";
 import { drizzle } from "drizzle-orm/better-sqlite3";
 import * as schema from "../db.schema";
+import { resetMainCreatedThreads } from "./mainCreatedThreads";
 import {
   assertRequiredDatabaseSchema,
   repairSafeSchemaDrift,
@@ -316,4 +317,5 @@ export function closeDatabase() {
   }
   _sqlite = undefined;
   _db = undefined;
+  resetMainCreatedThreads();
 }
diff --git a/src/main/db/mainCreatedThreads.ts b/src/main/db/mainCreatedThreads.ts
new file mode 100644
index 000000000..670fc489d
--- /dev/null
+++ b/src/main/db/mainCreatedThreads.ts
@@ -0,0 +1,36 @@
+/**
+ * Thread rows main inserted itself — remote `start` commands, schedules,
+ * orchestrator launches — that the renderer's store has not mirrored yet.
+ *
+ * The renderer persists its whole store through `dbSyncAll`, which deletes every
+ * thread row missing from that snapshot. A main-created row is missing from it
+ * until the forwarded `start` command reaches the renderer, and the delete
+ * cascades into `thread_runtime_items`: the launch turn's `user_message` (already
+ * persisted from the supervisor's emit) disappears, and later events are dropped
+ * until the renderer re-creates the row. Ids tracked here are exempt from that
+ * delete; the first renderer snapshot carrying an id hands ownership back to the
+ * renderer, so its own deletions keep working.
+ */
+const unmirroredThreadIds = new Set<string>();
+
+export function noteMainCreatedThread(threadId: string): void {
+  unmirroredThreadIds.add(threadId);
+}
+
+export function forgetMainCreatedThread(threadId: string): void {
+  unmirroredThreadIds.delete(threadId);
+}
+
+export function isMainCreatedThreadUnmirrored(threadId: string): boolean {
+  return unmirroredThreadIds.has(threadId);
+}
+
+/** A renderer snapshot arrived: every thread it carries is renderer-owned now. */
+export function acknowledgeMirroredThreadIds(threadIds: Iterable<string>): void {
+  for (const threadId of threadIds) unmirroredThreadIds.delete(threadId);
+}
+
+/** Tied to the open database — a new database starts with no pending rows. */
+export function resetMainCreatedThreads(): void {
+  unmirroredThreadIds.clear();
+}
diff --git a/src/main/db/projectsThreads.ts b/src/main/db/projectsThreads.ts
index a70e8647a..6d7e84342 100644
--- a/src/main/db/projectsThreads.ts
+++ b/src/main/db/projectsThreads.ts
@@ -2,6 +2,7 @@ import { asc, eq, notInArray } from "drizzle-orm";
 import type { Project, Thread } from "@/shared/contracts";
 import * as schema from "../db.schema";
 import { getDb } from "./connection";
+import { forgetMainCreatedThread, noteMainCreatedThread } from "./mainCreatedThreads";
 import { notifyProjectThreadDataChanged } from "./projectThreadChanges";
 import { projectMutableRow, rowToProject, rowToThread } from "./rowMappers";
 
@@ -84,6 +85,15 @@ export function dbUpdateProject(project: Project): void {
 
 export function dbUpsertThread(thread: Thread, sortOrder: number): void {
   const db = getDb();
+  // A row main inserts on its own is invisible to the renderer's store until the
+  // forwarded command reaches it, so shield it from `dbSyncAll`'s delete pass
+  // (see mainCreatedThreads).
+  const isNewRow =
+    db
+      .select({ id: schema.threads.id })
+      .from(schema.threads)
+      .where(eq(schema.threads.id, thread.id))
+      .get() === undefined;
   db.insert(schema.threads)
     .values({
       id: thread.id,
@@ -147,6 +157,7 @@ export function dbUpsertThread(thread: Thread, sortOrder: number): void {
       },
     })
     .run();
+  if (isNewRow) noteMainCreatedThread(thread.id);
   notifyProjectThreadDataChanged();
 }
 
@@ -182,6 +193,7 @@ export function dbMarkLiveThreadsInactive(): void {
 export function dbDeleteThread(threadId: string): void {
   const db = getDb();
   db.delete(schema.threads).where(eq(schema.threads.id, threadId)).run();
+  forgetMainCreatedThread(threadId);
   notifyProjectThreadDataChanged();
 }
 
diff --git a/src/main/db/sync.test.ts b/src/main/db/sync.test.ts
new file mode 100644
index 000000000..4bf636528
--- /dev/null
+++ b/src/main/db/sync.test.ts
@@ -0,0 +1,110 @@
+import { existsSync, mkdtempSync, rmSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import Database from "better-sqlite3";
+import { afterEach, beforeEach, describe, expect, it } from "vitest";
+import type { Project, Thread } from "@/shared/contracts";
+import { closeDatabase, initDatabase } from "./connection";
+import { dbGetThread, dbUpsertProject, dbUpsertThread } from "./projectsThreads";
+import { dbApplyThreadRuntimeEvents, dbGetThreadRuntimeItems } from "./runtimeItems";
+import { dbSyncAll } from "./sync";
+
+const serverNativeBinding = join(process.cwd(), "dist", "server-native", "better_sqlite3.node");
+let nativeBindingEnv: string | undefined;
+let sqliteAvailable = true;
+try {
+  new Database(":memory:").close();
+} catch {
+  if (existsSync(serverNativeBinding)) {
+    nativeBindingEnv = serverNativeBinding;
+  } else {
+    sqliteAvailable = false;
+  }
+}
+
+const project: Project = {
+  id: "project-1",
+  name: "Test project",
+  location: { kind: "posix", path: "/tmp/project" },
+  createdAt: "2026-01-01T00:00:00.000Z",
+};
+
+function remoteStartedThread(): Thread {
+  return {
+    id: "thread-remote",
+    projectId: project.id,
+    title: "Started from a remote client",
+    agentKind: "claude",
+    config: { model: "claude-opus-5" },
+    status: "launching",
+    attention: "none",
+    canResumeWithConfig: false,
+    archived: false,
+    done: false,
+    starred: false,
+    presentationMode: "gui",
+    createdAt: "2026-01-01T00:00:00.000Z",
+    updatedAt: "2026-01-01T00:00:00.000Z",
+  };
+}
+
+function persistLaunchUserMessage(threadId: string): void {
+  dbApplyThreadRuntimeEvents(threadId, [
+    { type: "turn.started", threadId, turnId: "turn-1" },
+    {
+      type: "item.started",
+      threadId,
+      itemId: "user-1",
+      itemType: "user_message",
+      payload: { content: [{ kind: "text", text: "fix the sidebar" }] },
+    },
+    { type: "item.completed", threadId, itemId: "user-1" },
+  ]);
+}
+
+describe.skipIf(!sqliteAvailable)("dbSyncAll thread ownership", () => {
+  let dir: string;
+
+  beforeEach(() => {
+    if (nativeBindingEnv) {
+      process.env.PORACODE_BETTER_SQLITE3_NATIVE_BINDING = nativeBindingEnv;
+    }
+    dir = mkdtempSync(join(tmpdir(), "poracode-sync-db-test-"));
+    initDatabase(join(dir, "state.sqlite"));
+    dbUpsertProject(project, 0);
+  });
+
+  afterEach(() => {
+    closeDatabase();
+    rmSync(dir, { recursive: true, force: true });
+    delete process.env.PORACODE_BETTER_SQLITE3_NATIVE_BINDING;
+  });
+
+  it("keeps a main-created thread (and its launch transcript) that the renderer has not mirrored yet", () => {
+    dbUpsertThread(remoteStartedThread(), 0);
+    persistLaunchUserMessage("thread-remote");
+
+    // Renderer flushes its store before the forwarded `start` command lands.
+    dbSyncAll([project], [], JSON.stringify({ kind: "home" }));
+
+    expect(dbGetThread("thread-remote")).not.toBeNull();
+    expect(dbGetThreadRuntimeItems("thread-remote").map((item) => item.type)).toEqual([
+      "user_message",
+    ]);
+  });
+
+  it("still deletes a thread the renderer dropped after it had mirrored it", () => {
+    dbUpsertThread(remoteStartedThread(), 0);
+    persistLaunchUserMessage("thread-remote");
+
+    // Renderer applied the command: its snapshot now carries the thread.
+    dbSyncAll([project], [remoteStartedThread()], JSON.stringify({ kind: "home" }));
+    expect(dbGetThreadRuntimeItems("thread-remote")).toHaveLength(1);
+
+    // The user deletes it in the renderer.
+    dbSyncAll([project], [], JSON.stringify({ kind: "home" }));
+
+    expect(dbGetThread("thread-remote")).toBeNull();
+    expect(dbGetThreadRuntimeItems("thread-remote")).toEqual([]);
+  });
+});
diff --git a/src/main/db/sync.ts b/src/main/db/sync.ts
index a2564345b..f90949a67 100644
--- a/src/main/db/sync.ts
+++ b/src/main/db/sync.ts
@@ -7,6 +7,7 @@ import {
 } from "@/shared/contracts";
 import type { DbPersistExperimentStatePayload } from "@/shared/ipc";
 import { getSqlite } from "./connection";
+import { acknowledgeMirroredThreadIds, isMainCreatedThreadUnmirrored } from "./mainCreatedThreads";
 import { notifyProjectThreadDataChanged } from "./projectThreadChanges";
 import { projectMutableRow } from "./rowMappers";
 
@@ -44,13 +45,20 @@ export function dbSyncAll(projectsData: Project[], threadsData: Thread[], viewJs
     const upsertThread = prepareThreadSyncStatement(sqlite);
 
     for (const tid of existingThreadIds) {
-      if (!incomingThreadIds.has(tid)) {
-        deleteThread.run(tid);
-      }
+      if (incomingThreadIds.has(tid)) continue;
+      // A thread main just created (remote `start`, schedule, orchestrator) is
+      // absent from this snapshot only because the renderer has not applied the
+      // forwarded command yet. Deleting it would cascade away the launch turn's
+      // runtime items — most visibly the initial `user_message`.
+      if (isMainCreatedThreadUnmirrored(tid)) continue;
+      deleteThread.run(tid);
     }
     for (let i = 0; i < threadsData.length; i++) {
       runThreadSync(upsertThread, threadsData[i]!, i);
     }
+    // Anything in this snapshot is renderer-owned from here on, so a later
+    // snapshot that drops it is a real deletion.
+    acknowledgeMirroredThreadIds(incomingThreadIds);
 
     sqlite
       .prepare(