Handle local agent connection recovery (#2853)

Handle connection-drop and retry behavior in local agent IPC handling.
Add an end-to-end scenario that verifies recovery after a temporary
local agent disconnect.
Align test fixtures and snapshots for local-agent reconnection behavior.

Author: wwwillchen

.gitignore

@@ -12,6 +12,8 @@ dist/
 # playwright
 playwright-report/
 test-results/
+blob-report/
+flakiness-report/
 
 # Diagnostic reports (https://nodejs.org/api/report.html)
 report.[0-9]*.[0-9]*.[0-9]*.[0-9]*.json

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

@@ -0,0 +1,29 @@
+import type { LocalAgentFixture } from "../../../../testing/fake-llm-server/localAgentTypes";
+
+/**
+ * Tests retry behavior when connection drops after tool-call chunks were emitted
+ * but before the stream is finalized. This simulates an orphaned tool-call retry
+ * window and ensures we don't duplicate tool execution.
+ */
+export const fixture: LocalAgentFixture = {
+  description: "Connection drop after streaming tool-call chunks",
+  dropConnectionAfterToolCallByTurn: [{ turnIndex: 0, attempts: [1] }],
+  turns: [
+    {
+      text: "I'll create a file for you.",
+      toolCalls: [
+        {
+          name: "write_file",
+          args: {
+            path: "src/recovered-after-tool-call.ts",
+            content: `export const recoveredAfterToolCall = true;\n`,
+            description: "File created after tool-call termination recovery",
+          },
+        },
+      ],
+    },
+    {
+      text: "Successfully created the file after retrying from a tool-call termination.",
+    },
+  ],
+};

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 +1,91 @@
+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);
+    const introText = po.page.getByText("I'll create a file for you.");
+    const completionText = po.page.getByText(
+      "Successfully created the file after automatic retry.",
+    );
+    await expect(introText).toHaveCount(1);
+    await expect(completionText).toHaveCount(1);
+    await expect(introText).toBeVisible();
+    await expect(completionText).toBeVisible();
+    // Partial chunks from the dropped attempt must not leak into final UI.
+    await expect(
+      po.page.getByText("Partial response before connection dr"),
+    ).toHaveCount(0);
+
+    // Verify exactly one recovered.ts edit card is shown in chat.
+    const recoveredEditCard = po.page.getByRole("button", {
+      name: /recovered\.ts .*src\/recovered\.ts.*Edit/,
+    });
+    await expect(recoveredEditCard).toHaveCount(1);
+
+    // The replayed conversation order must stay:
+    // intro assistant text -> tool edit card -> completion assistant text.
+    const introY = (await introText.boundingBox())?.y;
+    const editCardY = (await recoveredEditCard.boundingBox())?.y;
+    const completionY = (await completionText.boundingBox())?.y;
+    expect(introY).toBeDefined();
+    expect(editCardY).toBeDefined();
+    expect(completionY).toBeDefined();
+    expect(introY!).toBeLessThan(editCardY!);
+    expect(editCardY!).toBeLessThan(completionY!);
+
+    // Snapshot end state for chat + filesystem.
+    await po.snapshotMessages();
+    await po.snapshotAppFiles({
+      name: "after-connection-retry",
+      files: ["src/recovered.ts"],
+    });
+  },
+);
+
+testSkipIfWindows(
+  "local-agent - recovers when drop happens after tool-call stream",
+  async ({ po }) => {
+    await po.setUpDyadPro({ localAgent: true });
+    await po.importApp("minimal");
+    await po.chatActions.selectLocalAgentMode();
+
+    await po.sendPrompt("tc=local-agent/connection-drop-after-tool-call");
+
+    await expect(po.page.getByTestId("chat-error-box")).toHaveCount(0);
+    await expect(
+      po.page.getByText(
+        "Successfully created the file after retrying from a tool-call termination.",
+      ),
+    ).toBeVisible();
+
+    await expect(
+      po.page
+        .getByRole("button", {
+          name: /recovered-after-tool-call\.ts .*src\/recovered-after-tool-call\.ts.*Edit/,
+        })
+        .first(),
+    ).toBeVisible();
+
+    await po.snapshotAppFiles({
+      name: "after-tool-call-connection-retry",
+      files: ["src/recovered-after-tool-call.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_after-tool-call-connection-retry.txt

@@ -0,0 +1,2 @@
+=== src/recovered-after-tool-call.ts ===
+export const recoveredAfterToolCall = 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: ""