Handle local agent connection recovery

e2e-tests/fixtures/engine/local-agent/connection-drop.ts

@@ -0,0 +1,31 @@
+import type { LocalAgentFixture } from "../../../../testing/fake-llm-server/localAgentTypes";
+
+/**
+ * Tests automatic retry after connection drop (e.g., TCP terminated mid-stream).
+ * This fixture drops the connection on the first attempt of turn 1 (the
+ * post-tool text turn), which is more realistic than dropping before any
+ * tool activity. The local agent handler should automatically retry and
+ * continue without re-running completed work.
+ */
+export const fixture: LocalAgentFixture = {
+  description: "Automatic retry after connection drop",
+  dropConnectionByTurn: [{ turnIndex: 1, attempts: [1] }],
+  turns: [
+    {
+      text: "I'll create a file for you.",
+      toolCalls: [
+        {
+          name: "write_file",
+          args: {
+            path: "src/recovered.ts",
+            content: `export const recovered = true;\n`,
+            description: "File created after connection recovery",
+          },
+        },
+      ],
+    },
+    {
+      text: "Successfully created the file after automatic retry.",
+    },
+  ],
+};

e2e-tests/local_agent_connection_retry.spec.ts

@@ -0,0 +1,41 @@
+import { expect } from "@playwright/test";
+import { testSkipIfWindows } from "./helpers/test_helper";
+
+/**
+ * E2E test for local-agent connection retry resilience.
+ * Verifies that the agent automatically recovers from transient connection
+ * drops (e.g., TCP terminated mid-stream) by retrying the stream.
+ */
+
+testSkipIfWindows(
+  "local-agent - recovers from connection drop",
+  async ({ po }) => {
+    await po.setUpDyadPro({ localAgent: true });
+    await po.importApp("minimal");
+    await po.chatActions.selectLocalAgentMode();
+
+    // The connection-drop fixture drops on turn 1 (after a tool turn already
+    // completed) to simulate a realistic interrupted follow-up request.
+    await po.sendPrompt("tc=local-agent/connection-drop");
+
+    // Verify the turn still completed and no error box leaked to the UI.
+    await expect(po.page.getByTestId("chat-error-box")).toHaveCount(0);
+    await expect(
+      po.page.getByText("Successfully created the file after automatic retry."),
+    ).toBeVisible();
+
+    // Verify exactly one recovered.ts edit card is shown in chat.
+    await expect(
+      po.page.getByRole("button", {
+        name: /recovered\.ts .*src\/recovered\.ts.*Edit/,
+      }),
+    ).toHaveCount(1);
+
+    // Snapshot end state for chat + filesystem.
+    await po.snapshotMessages();
+    await po.snapshotAppFiles({
+      name: "after-connection-retry",
+      files: ["src/recovered.ts"],
+    });
+  },
+);

e2e-tests/snapshots/local_agent_connection_retry.spec.ts_after-connection-retry.txt

@@ -0,0 +1,2 @@
+=== src/recovered.ts ===
+export const recovered = true;

e2e-tests/snapshots/local_agent_connection_retry.spec.ts_local-agent---recovers-from-connection-drop-1.aria.yml

@@ -0,0 +1,48 @@
+- paragraph: /Generate an AI_RULES\.md file for this app\. Describe the tech stack in 5-\d+ bullet points and describe clear rules about what libraries to use for what\./
+- button "file1.txt file1.txt Edit":
+  - img
+  - text: ""
+  - button "Edit":
+    - img
+    - text: ""
+  - img
+- paragraph: More EOM
+- button "Copy":
+  - img
+- img
+- text: Approved
+- img
+- text: claude-opus-4-5
+- img
+- text: less than a minute ago
+- img
+- text: (1 files changed)
+- button "Copy Request ID":
+  - img
+  - text: ""
+- paragraph: tc=local-agent/connection-drop
+- paragraph: I'll create a file for you.
+- 'button "recovered.ts src/recovered.ts Edit Summary: File created after connection recovery"':
+  - img
+  - text: ""
+  - button "Edit":
+    - img
+    - text: ""
+  - img
+  - text: ""
+- paragraph: Successfully created the file after automatic retry.
+- button "Copy":
+  - img
+- img
+- text: claude-opus-4-5
+- img
+- text: less than a minute ago
+- button "Copy Request ID":
+  - img
+  - text: ""
+- button "Undo":
+  - img
+  - text: ""
+- button "Retry":
+  - img
+  - text: ""

src/__tests__/local_agent_handler.test.ts

@@ -847,6 +847,184 @@ describe("handleLocalAgentStream", () => {
       expect(lastContentUpdate.data.content).toContain("Hello, ");
       expect(lastContentUpdate.data.content).toContain("world!");
     });
+
+    it("should retry and resume when a stream terminates transiently", async () => {
+      // Arrange
+      const { event, getMessagesByChannel } = createFakeEvent();
+      mockSettings = buildTestSettings({ enableDyadPro: true });
+      mockChatData = buildTestChat();
+
+      const streamMessagesByAttempt: any[][] = [];
+      let attemptCount = 0;
+      mockStreamTextImpl = (options) => {
+        attemptCount += 1;
+        streamMessagesByAttempt.push(options.messages ?? []);
+
+        if (attemptCount === 1) {
+          return {
+            fullStream: (async function* () {
+              yield { type: "text-delta", text: "Partial response. " };
+              throw new TypeError("terminated");
+            })(),
+            response: Promise.resolve({ messages: [] }),
+            steps: Promise.resolve([]),
+          };
+        }
+
+        return {
+          fullStream: (async function* () {
+            yield { type: "text-delta", text: "Recovered output." };
+          })(),
+          response: Promise.resolve({
+            messages: [
+              {
+                role: "assistant",
+                content: [{ type: "text", text: "Recovered output." }],
+              },
+            ],
+          }),
+          steps: Promise.resolve([{ toolCalls: [] }]),
+        };
+      };
+
+      // Act
+      await handleLocalAgentStream(
+        event,
+        { chatId: 1, prompt: "test" },
+        new AbortController(),
+        {
+          placeholderMessageId: 10,
+          systemPrompt: "You are helpful",
+          dyadRequestId,
+        },
+      );
+
+      // Assert
+      expect(attemptCount).toBe(2);
+      expect(getMessagesByChannel("chat:response:error")).toHaveLength(0);
+
+      const contentUpdates = dbOperations.updates.filter(
+        (u) => u.data.content !== undefined,
+      );
+      const finalContent = contentUpdates[contentUpdates.length - 1].data
+        .content as string;
+      expect(finalContent).toContain("Partial response.");
+      expect(finalContent).toContain("Recovered output.");
+
+      const continuationInstructionFound = (
+        streamMessagesByAttempt[1] ?? []
+      ).some(
+        (message: any) =>
+          message.role === "user" &&
+          Array.isArray(message.content) &&
+          message.content.some(
+            (part: any) =>
+              part.type === "text" &&
+              typeof part.text === "string" &&
+              part.text.includes(
+                "previous response stream was interrupted by a transient network error",
+              ),
+          ),
+      );
+      expect(continuationInstructionFound).toBe(true);
+    });
+
+    it("should replay emitted tool events before retrying a terminated stream", async () => {
+      // Arrange
+      const { event, getMessagesByChannel } = createFakeEvent();
+      mockSettings = buildTestSettings({ enableDyadPro: true });
+      mockChatData = buildTestChat();
+
+      const streamMessagesByAttempt: any[][] = [];
+      let attemptCount = 0;
+      mockStreamTextImpl = (options) => {
+        attemptCount += 1;
+        streamMessagesByAttempt.push(options.messages ?? []);
+
+        if (attemptCount === 1) {
+          return {
+            fullStream: (async function* () {
+              yield { type: "text-delta", text: "Working with tools. " };
+              yield {
+                type: "tool-call",
+                toolCallId: "call_replay_1",
+                toolName: "read_file",
+                input: { path: "README.md" },
+              };
+              yield {
+                type: "tool-result",
+                toolCallId: "call_replay_1",
+                toolName: "read_file",
+                output: "README content",
+              };
+              throw new TypeError("terminated");
+            })(),
+            response: Promise.resolve({ messages: [] }),
+            steps: Promise.resolve([]),
+          };
+        }
+
+        return {
+          fullStream: (async function* () {
+            yield { type: "text-delta", text: "Resumed after replay." };
+          })(),
+          response: Promise.resolve({
+            messages: [
+              {
+                role: "assistant",
+                content: [{ type: "text", text: "Resumed after replay." }],
+              },
+            ],
+          }),
+          steps: Promise.resolve([{ toolCalls: [] }]),
+        };
+      };
+
+      // Act
+      await handleLocalAgentStream(
+        event,
+        { chatId: 1, prompt: "test" },
+        new AbortController(),
+        {
+          placeholderMessageId: 10,
+          systemPrompt: "You are helpful",
+          dyadRequestId,
+        },
+      );
+
+      // Assert
+      expect(attemptCount).toBe(2);
+      expect(getMessagesByChannel("chat:response:error")).toHaveLength(0);
+
+      const secondAttemptMessages = streamMessagesByAttempt[1] ?? [];
+      const hasReplayedToolCall = secondAttemptMessages.some(
+        (message: any) =>
+          message.role === "assistant" &&
+          Array.isArray(message.content) &&
+          message.content.some(
+            (part: any) =>
+              part.type === "tool-call" &&
+              part.toolCallId === "call_replay_1" &&
+              part.toolName === "read_file",
+          ),
+      );
+      const hasReplayedToolResult = secondAttemptMessages.some(
+        (message: any) =>
+          message.role === "tool" &&
+          Array.isArray(message.content) &&
+          message.content.some(
+            (part: any) =>
+              part.type === "tool-result" &&
+              part.toolCallId === "call_replay_1" &&
+              part.toolName === "read_file" &&
+              part.output?.type === "text" &&
+              part.output?.value === "README content",
+          ),
+      );
+
+      expect(hasReplayedToolCall).toBe(true);
+      expect(hasReplayedToolResult).toBe(true);
+    });
   });
 
   describe("Stream processing - reasoning blocks", () => {