diff --git a/packages/coding-agent/src/core/gateway/durable-chat-run.ts b/packages/coding-agent/src/core/gateway/durable-chat-run.ts
new file mode 100644
index 0000000..a16a349
--- /dev/null
+++ b/packages/coding-agent/src/core/gateway/durable-chat-run.ts
@@ -0,0 +1,246 @@
+import type { AgentMessage } from "@mariozechner/companion-agent-core";
+import type { AgentSessionEvent } from "../agent-session.js";
+import { extractMessageText } from "./helpers.js";
+import { messageContentToHistoryParts } from "./session-state.js";
+import type { GatewayTransientToolResult } from "./session-state.js";
+import type { GatewayMessageResult, GatewayMessageRequest } from "./types.js";
+
+const FLUSH_INTERVAL_MS = 500;
+
+type PersistHistoryItem = {
+  role: "user" | "assistant" | "toolResult";
+  text?: string;
+  partsJson: string;
+  timestamp: number;
+  idempotencyKey: string;
+};
+
+type ConvexRunStatus = "completed" | "failed" | "interrupted";
+
+function normalizeErrorMessage(error: unknown): string {
+  if (error instanceof Error) {
+    return error.message;
+  }
+  return typeof error === "string" ? error : String(error);
+}
+
+type DurableChatRunEventBody =
+  | {
+      items: PersistHistoryItem[];
+      final?: {
+        status: ConvexRunStatus;
+        error?: string;
+      };
+    }
+  | {
+      items?: PersistHistoryItem[];
+      final: {
+        status: ConvexRunStatus;
+        error?: string;
+      };
+    };
+
+function buildAuthHeaders(token: string): Record<string, string> {
+  return {
+    "Content-Type": "application/json",
+    Authorization: `Bearer ${token}`,
+  };
+}
+
+export class DurableChatRunReporter {
+  private readonly assistantMessageId: string;
+  private latestAssistantMessage: AgentMessage | null = null;
+  private readonly knownToolResults = new Map<
+    string,
+    GatewayTransientToolResult
+  >();
+  private flushTimer: ReturnType<typeof globalThis.setTimeout> | null = null;
+  private flushChain: Promise<void> = Promise.resolve();
+  private flushFailure: Error | null = null;
+
+  constructor(
+    private readonly durableRun: NonNullable<
+      GatewayMessageRequest["durableRun"]
+    >,
+  ) {
+    if (
+      durableRun.callbackUrl.trim().length === 0 ||
+      durableRun.callbackToken.trim().length === 0
+    ) {
+      throw new Error(
+        "Durable chat run reporting requires callbackUrl and callbackToken",
+      );
+    }
+    this.assistantMessageId = `run:${this.durableRun.runId}:assistant`;
+  }
+
+  handleSessionEvent(
+    event: AgentSessionEvent,
+    pendingToolResults: GatewayTransientToolResult[],
+  ): void {
+    for (const toolResult of pendingToolResults) {
+      this.knownToolResults.set(toolResult.toolCallId, toolResult);
+    }
+
+    if (event.type === "message_start" && event.message.role === "assistant") {
+      this.latestAssistantMessage = event.message;
+      return;
+    }
+
+    if (event.type === "message_update" && event.message.role === "assistant") {
+      this.latestAssistantMessage = event.message;
+      this.scheduleFlush();
+      return;
+    }
+
+    if (event.type === "message_end" && event.message.role === "assistant") {
+      this.latestAssistantMessage = event.message;
+      this.scheduleFlush();
+      return;
+    }
+
+    if (
+      event.type === "tool_execution_end" ||
+      event.type === "turn_end" ||
+      (event.type === "message_end" && event.message.role === "toolResult")
+    ) {
+      this.scheduleFlush();
+    }
+  }
+
+  async finalize(result: GatewayMessageResult): Promise<void> {
+    let status: ConvexRunStatus = result.ok
+      ? "completed"
+      : result.error?.includes("aborted")
+        ? "interrupted"
+        : "failed";
+    let errorMessage = result.error;
+
+    try {
+      await this.finalFlush();
+    } catch (error) {
+      status = "failed";
+      errorMessage = normalizeErrorMessage(error);
+    }
+    await this.postEvent({
+      final: {
+        status,
+        ...(status === "failed" && errorMessage ? { error: errorMessage } : {}),
+      },
+    });
+  }
+
+  private scheduleFlush(): void {
+    if (this.flushTimer) return;
+    this.flushTimer = globalThis.setTimeout(() => {
+      this.flushTimer = null;
+      void this.flush().catch(() => undefined);
+    }, FLUSH_INTERVAL_MS);
+  }
+
+  private async flush(): Promise<void> {
+    this.throwIfFlushFailed();
+    if (this.flushTimer) {
+      globalThis.clearTimeout(this.flushTimer);
+      this.flushTimer = null;
+    }
+
+    const items = this.buildItems();
+    if (items.length === 0) {
+      return;
+    }
+
+    const flushPromise = this.flushChain.then(async () => {
+      this.throwIfFlushFailed();
+      await this.postEvent({
+        items,
+      });
+    });
+    this.flushChain = flushPromise.catch(() => undefined);
+
+    try {
+      await flushPromise;
+    } catch (error) {
+      throw this.markFlushFailed(error);
+    }
+  }
+
+  private async finalFlush(): Promise<void> {
+    await this.flush();
+    await this.flushChain;
+    this.throwIfFlushFailed();
+  }
+
+  private buildItems(): PersistHistoryItem[] {
+    const assistantParts =
+      this.latestAssistantMessage?.role === "assistant"
+        ? messageContentToHistoryParts(this.latestAssistantMessage)
+        : [];
+
+    for (const toolResult of this.knownToolResults.values()) {
+      assistantParts.push({
+        type: "tool-invocation",
+        toolCallId: toolResult.toolCallId,
+        toolName: toolResult.toolName,
+        args: undefined,
+        state: toolResult.isError ? "error" : "result",
+        result: toolResult.result,
+      });
+    }
+
+    const firstToolResult = this.knownToolResults.values().next().value;
+
+    if (
+      this.latestAssistantMessage?.role === "assistant" ||
+      assistantParts.length > 0
+    ) {
+      return [
+        {
+          role: "assistant",
+          text:
+            this.latestAssistantMessage?.role === "assistant"
+              ? extractMessageText(this.latestAssistantMessage) || undefined
+              : undefined,
+          partsJson: JSON.stringify(assistantParts),
+          timestamp:
+            this.latestAssistantMessage?.timestamp ??
+            firstToolResult?.timestamp ??
+            Date.now(),
+          idempotencyKey: this.assistantMessageId,
+        },
+      ];
+    }
+
+    return [];
+  }
+
+  private async postEvent(body: DurableChatRunEventBody): Promise<void> {
+    const response = await fetch(this.durableRun.callbackUrl, {
+      method: "POST",
+      headers: buildAuthHeaders(this.durableRun.callbackToken),
+      body: JSON.stringify(body),
+    });
+    if (!response.ok) {
+      const text = await response.text().catch(() => "");
+      throw new Error(
+        `Chat run relay failed: ${response.status} ${text}`.trim(),
+      );
+    }
+  }
+
+  private throwIfFlushFailed(): void {
+    if (this.flushFailure) {
+      throw this.flushFailure;
+    }
+  }
+
+  private markFlushFailed(error: unknown): Error {
+    if (this.flushFailure) {
+      return this.flushFailure;
+    }
+    const normalizedError =
+      error instanceof Error ? error : new Error(normalizeErrorMessage(error));
+    this.flushFailure = normalizedError;
+    return normalizedError;
+  }
+}
diff --git a/packages/coding-agent/src/core/gateway/internal-types.ts b/packages/coding-agent/src/core/gateway/internal-types.ts
index 88274d4..2bbb086 100644
--- a/packages/coding-agent/src/core/gateway/internal-types.ts
+++ b/packages/coding-agent/src/core/gateway/internal-types.ts
@@ -1,5 +1,6 @@
 import type { AgentMessage } from "@mariozechner/companion-agent-core";
 import type { AgentSession } from "../agent-session.js";
+import type { DurableChatRunReporter } from "./durable-chat-run.js";
 import type {
   GatewayMessageRequest,
   GatewayMessageResult,
@@ -63,7 +64,13 @@ export type GatewayEvent =
       payload: {
         teamId: string;
         status: string;
-        members: Array<{ id: string; name: string; role?: string; status: string; message?: string }>;
+        members: Array<{
+          id: string;
+          name: string;
+          role?: string;
+          status: string;
+          message?: string;
+        }>;
       };
     }
   | {
@@ -84,6 +91,7 @@ export interface ManagedGatewaySession {
   session: AgentSession;
   queue: GatewayQueuedMessage[];
   processing: boolean;
+  activeDurableRun: DurableChatRunReporter | null;
   activeAssistantMessage: AgentMessage | null;
   pendingToolResults: GatewayTransientToolResult[];
   createdAt: number;
diff --git a/packages/coding-agent/src/core/gateway/runtime.ts b/packages/coding-agent/src/core/gateway/runtime.ts
index c8df267..586979a 100644
--- a/packages/coding-agent/src/core/gateway/runtime.ts
+++ b/packages/coding-agent/src/core/gateway/runtime.ts
@@ -10,6 +10,7 @@ import { URL } from "node:url";
 import type { AgentMessage } from "@mariozechner/companion-agent-core";
 import type { AgentSession, AgentSessionEvent } from "../agent-session.js";
 import type { Settings } from "../settings-manager.js";
+import { DurableChatRunReporter } from "./durable-chat-run.js";
 import { extractMessageText, getLastAssistantText } from "./helpers.js";
 import {
   type GatewayEvent,
@@ -108,6 +109,28 @@ function readString(value: unknown): string | undefined {
   return trimmed.length > 0 ? trimmed : undefined;
 }
 
+function readDurableRun(
+  value: unknown,
+): GatewayMessageRequest["durableRun"] | undefined {
+  if (!isRecord(value)) {
+    return undefined;
+  }
+
+  const runId = readString(value.runId);
+  const callbackUrl = readString(value.callbackUrl);
+  const callbackToken = readString(value.callbackToken);
+
+  if (!runId || !callbackUrl || !callbackToken) {
+    return undefined;
+  }
+
+  return {
+    runId,
+    callbackUrl,
+    callbackToken,
+  };
+}
+
 export function setActiveGatewayRuntime(runtime: GatewayRuntime | null): void {
   activeGatewayRuntime = runtime;
 }
@@ -419,6 +442,7 @@ export class GatewayRuntime {
       session,
       queue: [],
       processing: false,
+      activeDurableRun: null,
       activeAssistantMessage: null,
       pendingToolResults: [],
       createdAt: Date.now(),
@@ -462,18 +486,32 @@ export class GatewayRuntime {
     );
     this.emitState(managedSession);
 
+    let result: GatewayMessageResult = {
+      ok: false,
+      response: "",
+      error: "Unknown error",
+      sessionKey: managedSession.sessionKey,
+    };
+    let durableRunReporter: DurableChatRunReporter | null = null;
+
     try {
       queued.onStart?.();
+      if (queued.request.durableRun) {
+        durableRunReporter = new DurableChatRunReporter(
+          queued.request.durableRun,
+        );
+        managedSession.activeDurableRun = durableRunReporter;
+      }
       await managedSession.session.prompt(queued.request.text, {
         images: queued.request.images,
         source: queued.request.source ?? "extension",
       });
       const response = getLastAssistantText(managedSession.session);
-      queued.resolve({
+      result = {
         ok: true,
         response,
         sessionKey: managedSession.sessionKey,
-      });
+      };
     } catch (error) {
       const message = error instanceof Error ? error.message : String(error);
       this.log(
@@ -491,15 +529,39 @@ export class GatewayRuntime {
           error: message,
         });
       }
-      queued.resolve({
+      result = {
         ok: false,
         response: "",
         error: message,
         sessionKey: managedSession.sessionKey,
-      });
+      };
     } finally {
       queued.onFinish?.();
+      if (durableRunReporter) {
+        try {
+          await durableRunReporter.finalize(result);
+        } catch (error) {
+          const message =
+            error instanceof Error ? error.message : String(error);
+          this.log(
+            `[chat-run] session=${managedSession.sessionKey} finalize error: ${message}`,
+          );
+          this.emit(managedSession, {
+            type: "error",
+            sessionKey: managedSession.sessionKey,
+            error: message,
+          });
+          result = {
+            ok: false,
+            response: result.response,
+            error: message,
+            sessionKey: managedSession.sessionKey,
+          };
+        }
+      }
+      queued.resolve(result);
       managedSession.processing = false;
+      managedSession.activeDurableRun = null;
       managedSession.activeAssistantMessage = null;
       managedSession.pendingToolResults = [];
       managedSession.lastActiveAt = Date.now();
@@ -529,6 +591,13 @@ export class GatewayRuntime {
     managedSession: ManagedGatewaySession,
     event: AgentSessionEvent,
   ): void {
+    const forwardToDurableRun = () => {
+      managedSession.activeDurableRun?.handleSessionEvent(
+        event,
+        managedSession.pendingToolResults,
+      );
+    };
+
     switch (event.type) {
       case "turn_start":
         managedSession.lastActiveAt = Date.now();
@@ -537,6 +606,7 @@ export class GatewayRuntime {
           type: "turn_start",
           sessionKey: managedSession.sessionKey,
         });
+        forwardToDurableRun();
         return;
       case "turn_end":
         managedSession.lastActiveAt = Date.now();
@@ -545,6 +615,7 @@ export class GatewayRuntime {
           type: "turn_end",
           sessionKey: managedSession.sessionKey,
         });
+        forwardToDurableRun();
         return;
       case "message_start":
         managedSession.lastActiveAt = Date.now();
@@ -556,6 +627,7 @@ export class GatewayRuntime {
           sessionKey: managedSession.sessionKey,
           role: event.message.role,
         });
+        forwardToDurableRun();
         return;
       case "message_update":
         managedSession.lastActiveAt = Date.now();
@@ -570,6 +642,7 @@ export class GatewayRuntime {
               delta: event.assistantMessageEvent.delta,
               contentIndex: event.assistantMessageEvent.contentIndex,
             });
+            forwardToDurableRun();
             return;
           case "thinking_delta":
             this.emit(managedSession, {
@@ -578,8 +651,10 @@ export class GatewayRuntime {
               delta: event.assistantMessageEvent.delta,
               contentIndex: event.assistantMessageEvent.contentIndex,
             });
+            forwardToDurableRun();
             return;
         }
+        forwardToDurableRun();
         return;
       case "message_end":
         managedSession.lastActiveAt = Date.now();
@@ -595,6 +670,7 @@ export class GatewayRuntime {
             text: extractMessageText(event.message),
           });
           this.emitStructuredParts(managedSession, event.message);
+          forwardToDurableRun();
           return;
         }
         if (event.message.role === "toolResult") {
@@ -610,6 +686,7 @@ export class GatewayRuntime {
               );
           }
         }
+        forwardToDurableRun();
         return;
       case "tool_execution_start":
         managedSession.lastActiveAt = Date.now();
@@ -624,6 +701,7 @@ export class GatewayRuntime {
           toolName: event.toolName,
           args: event.args,
         });
+        forwardToDurableRun();
         return;
       case "tool_execution_update":
         managedSession.lastActiveAt = Date.now();
@@ -634,6 +712,7 @@ export class GatewayRuntime {
           toolName: event.toolName,
           partialResult: event.partialResult,
         });
+        forwardToDurableRun();
         return;
       case "tool_execution_end":
         managedSession.lastActiveAt = Date.now();
@@ -661,6 +740,7 @@ export class GatewayRuntime {
           result: event.result,
           isError: event.isError,
         });
+        forwardToDurableRun();
         return;
     }
   }
@@ -1030,7 +1110,7 @@ export class GatewayRuntime {
     }
 
     const sessionMatch = path.match(
-      /^\/sessions\/([^/]+)(?:\/(events|messages|abort|reset|chat|history|model|reload|state|steer))?$/,
+      /^\/sessions\/([^/]+)(?:\/(enqueue|events|messages|abort|reset|chat|history|model|reload|state|steer))?$/,
     );
     if (!sessionMatch) {
       this.writeJson(response, 404, { error: "Not found" });
@@ -1069,6 +1149,37 @@ export class GatewayRuntime {
       return;
     }
 
+    if (action === "enqueue" && method === "POST") {
+      const body = await this.readJsonBody(request);
+      const text = extractUserText(body);
+      if (!text) {
+        this.writeJson(response, 400, { error: "Missing user message text" });
+        return;
+      }
+      const durableRun = readDurableRun(body.durableRun);
+      const queued = await this.queueManagedMessage({
+        request: {
+          sessionKey,
+          text,
+          source: "extension",
+          metadata: isRecord(body.metadata) ? body.metadata : undefined,
+          durableRun,
+        },
+      });
+      if (!queued.accepted) {
+        this.writeJson(response, 409, queued.errorResult);
+        return;
+      }
+      void queued.completion.catch(() => undefined);
+      this.writeJson(response, 202, {
+        ok: true,
+        queued: true,
+        sessionKey,
+        ...(durableRun ? { runId: durableRun.runId } : {}),
+      });
+      return;
+    }
+
     if (action === "messages" && method === "POST") {
       const body = await this.readJsonBody(request);
       const text = typeof body.text === "string" ? body.text : "";
diff --git a/packages/coding-agent/src/core/gateway/types.ts b/packages/coding-agent/src/core/gateway/types.ts
index 9aed60d..2311a43 100644
--- a/packages/coding-agent/src/core/gateway/types.ts
+++ b/packages/coding-agent/src/core/gateway/types.ts
@@ -26,6 +26,11 @@ export interface GatewayMessageRequest {
   source?: "interactive" | "rpc" | "extension";
   images?: ImageContent[];
   metadata?: Record<string, unknown>;
+  durableRun?: {
+    runId: string;
+    callbackUrl: string;
+    callbackToken: string;
+  };
 }
 
 export interface GatewayMessageResult {
diff --git a/packages/coding-agent/test/durable-chat-run.test.ts b/packages/coding-agent/test/durable-chat-run.test.ts
new file mode 100644
index 0000000..6a774da
--- /dev/null
+++ b/packages/coding-agent/test/durable-chat-run.test.ts
@@ -0,0 +1,157 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { DurableChatRunReporter } from "../src/core/gateway/durable-chat-run.js";
+
+function mockOkResponse() {
+  return {
+    ok: true,
+    status: 200,
+    text: vi.fn().mockResolvedValue(""),
+  } as unknown as Response;
+}
+
+describe("DurableChatRunReporter", () => {
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it("posts assistant state to the relay and completes the run", async () => {
+    const fetchMock = vi.fn<typeof fetch>().mockResolvedValue(mockOkResponse());
+    vi.stubGlobal("fetch", fetchMock);
+
+    const reporter = new DurableChatRunReporter({
+      runId: "run-1",
+      callbackUrl: "https://web.example/api/chat/runs/run-1/events",
+      callbackToken: "callback-token",
+    });
+
+    const assistantMessage = {
+      role: "assistant",
+      timestamp: 111,
+      content: [{ type: "text", text: "hello from the sandbox" }],
+    };
+
+    reporter.handleSessionEvent(
+      {
+        type: "message_start",
+        message: assistantMessage,
+      } as never,
+      [],
+    );
+    reporter.handleSessionEvent(
+      {
+        type: "message_update",
+        message: assistantMessage,
+        assistantMessageEvent: {
+          type: "text_delta",
+          delta: "hello from the sandbox",
+          contentIndex: 0,
+        },
+      } as never,
+      [],
+    );
+    reporter.handleSessionEvent(
+      {
+        type: "tool_execution_end",
+        toolCallId: "call-1",
+        toolName: "bash",
+        result: { stdout: "done" },
+        isError: false,
+      } as never,
+      [
+        {
+          toolCallId: "call-1",
+          toolName: "bash",
+          result: { stdout: "done" },
+          isError: false,
+          timestamp: 222,
+        },
+      ],
+    );
+
+    await reporter.finalize({
+      ok: true,
+      response: "hello from the sandbox",
+      sessionKey: "session-1",
+    });
+
+    expect(fetchMock).toHaveBeenCalledTimes(2);
+    expect(fetchMock.mock.calls[0]?.[0]).toBe(
+      "https://web.example/api/chat/runs/run-1/events",
+    );
+    expect(fetchMock.mock.calls[1]?.[0]).toBe(
+      "https://web.example/api/chat/runs/run-1/events",
+    );
+
+    expect(fetchMock.mock.calls[0]?.[1]?.headers).toMatchObject({
+      Authorization: "Bearer callback-token",
+      "Content-Type": "application/json",
+    });
+
+    const runMessagesCall = fetchMock.mock.calls.find((call) =>
+      String(call[1]?.body).includes('"items"'),
+    );
+    const runMessagesBody = JSON.parse(String(runMessagesCall?.[1]?.body)) as {
+      items: Array<{
+        idempotencyKey: string;
+        partsJson: string;
+      }>;
+    };
+    expect(runMessagesBody.items).toHaveLength(1);
+    expect(runMessagesBody.items[0]).toMatchObject({
+      idempotencyKey: "run:run-1:assistant",
+    });
+    expect(JSON.parse(runMessagesBody.items[0]?.partsJson ?? "[]")).toEqual(
+      expect.arrayContaining([
+        expect.objectContaining({
+          type: "text",
+          text: "hello from the sandbox",
+        }),
+        expect.objectContaining({
+          type: "tool-invocation",
+          toolCallId: "call-1",
+          toolName: "bash",
+          state: "result",
+          result: { stdout: "done" },
+        }),
+      ]),
+    );
+
+    expect(
+      JSON.parse(String(fetchMock.mock.calls[1]?.[1]?.body)),
+    ).toMatchObject({
+      final: {
+        status: "completed",
+      },
+    });
+  });
+
+  it("marks aborted runs as interrupted", async () => {
+    const fetchMock = vi.fn<typeof fetch>().mockResolvedValue(mockOkResponse());
+    vi.stubGlobal("fetch", fetchMock);
+
+    const reporter = new DurableChatRunReporter({
+      runId: "run-2",
+      callbackUrl: "https://web.example/api/chat/runs/run-2/events",
+      callbackToken: "callback-token",
+    });
+
+    await reporter.finalize({
+      ok: false,
+      response: "",
+      error: "Session aborted",
+      sessionKey: "session-1",
+    });
+
+    expect(fetchMock).toHaveBeenCalledTimes(1);
+    expect(fetchMock.mock.calls[0]?.[0]).toBe(
+      "https://web.example/api/chat/runs/run-2/events",
+    );
+    expect(
+      JSON.parse(String(fetchMock.mock.calls[0]?.[1]?.body)),
+    ).toMatchObject({
+      final: {
+        status: "interrupted",
+      },
+    });
+  });
+});
diff --git a/packages/coding-agent/test/gateway-session-titles.test.ts b/packages/coding-agent/test/gateway-session-titles.test.ts
index 9846f19..2573e2f 100644
--- a/packages/coding-agent/test/gateway-session-titles.test.ts
+++ b/packages/coding-agent/test/gateway-session-titles.test.ts
@@ -49,6 +49,7 @@ function addManagedSession(
     session,
     queue: [],
     processing: false,
+    activeDurableRun: null,
     activeAssistantMessage: null,
     pendingToolResults: [],
     createdAt: Date.now(),
diff --git a/packages/coding-agent/test/gateway-steer.test.ts b/packages/coding-agent/test/gateway-steer.test.ts
index 19d2d29..0a63ca4 100644
--- a/packages/coding-agent/test/gateway-steer.test.ts
+++ b/packages/coding-agent/test/gateway-steer.test.ts
@@ -49,6 +49,7 @@ function addManagedSession(
     session: session as never,
     queue: [],
     processing,
+    activeDurableRun: null,
     activeAssistantMessage: null,
     pendingToolResults: [],
     createdAt: Date.now(),