diff --git a/base-action/src/execution-file.ts b/base-action/src/execution-file.ts
new file mode 100644
index 000000000..3cf396191
--- /dev/null
+++ b/base-action/src/execution-file.ts
@@ -0,0 +1,42 @@
+import * as core from "@actions/core";
+import { existsSync } from "fs";
+import { writeFile } from "fs/promises";
+import { join } from "path";
+
+const EXECUTION_FILENAME = "claude-execution-output.json";
+
+export function getExecutionFilePath(): string | undefined {
+  if (!process.env.RUNNER_TEMP) {
+    return undefined;
+  }
+  return join(process.env.RUNNER_TEMP, EXECUTION_FILENAME);
+}
+
+export async function writeExecutionFile(
+  messages: unknown[],
+): Promise<string | undefined> {
+  const executionFile = getExecutionFilePath();
+  if (!executionFile) {
+    core.warning("Failed to write execution file: RUNNER_TEMP is not set");
+    return undefined;
+  }
+
+  try {
+    await writeFile(executionFile, JSON.stringify(messages, null, 2));
+    console.log(`Log saved to ${executionFile}`);
+    return executionFile;
+  } catch (error) {
+    core.warning(`Failed to write execution file: ${error}`);
+    return undefined;
+  }
+}
+
+export function setExecutionFileOutputIfPresent(): string | undefined {
+  const executionFile = getExecutionFilePath();
+  if (!executionFile || !existsSync(executionFile)) {
+    return undefined;
+  }
+
+  core.setOutput("execution_file", executionFile);
+  return executionFile;
+}
diff --git a/base-action/src/index.ts b/base-action/src/index.ts
index 160e64154..8ec84ac1b 100644
--- a/base-action/src/index.ts
+++ b/base-action/src/index.ts
@@ -6,6 +6,7 @@ import { runClaude } from "./run-claude";
 import { setupClaudeCodeSettings } from "./setup-claude-code-settings";
 import { validateEnvironmentVariables } from "./validate-env";
 import { installPlugins } from "./install-plugins";
+import { setExecutionFileOutputIfPresent } from "./execution-file";
 
 async function run() {
   try {
@@ -62,6 +63,7 @@ async function run() {
       core.setOutput("structured_output", result.structuredOutput);
     }
   } catch (error) {
+    setExecutionFileOutputIfPresent();
     core.setFailed(`Action failed with error: ${error}`);
     core.setOutput("conclusion", "failure");
     process.exit(1);
diff --git a/base-action/src/run-claude-sdk.ts b/base-action/src/run-claude-sdk.ts
index e37184a7f..e65d93c26 100644
--- a/base-action/src/run-claude-sdk.ts
+++ b/base-action/src/run-claude-sdk.ts
@@ -1,5 +1,5 @@
 import * as core from "@actions/core";
-import { readFile, writeFile, access } from "fs/promises";
+import { readFile, access } from "fs/promises";
 import { dirname, join } from "path";
 import { query } from "@anthropic-ai/claude-agent-sdk";
 import type {
@@ -8,6 +8,7 @@ import type {
   SDKUserMessage,
 } from "@anthropic-ai/claude-agent-sdk";
 import type { ParsedSdkOptions } from "./parse-sdk-options";
+import { writeExecutionFile } from "./execution-file";
 
 export type ClaudeRunResult = {
   executionFile?: string;
@@ -16,8 +17,6 @@ export type ClaudeRunResult = {
   structuredOutput?: string;
 };
 
-const EXECUTION_FILE = `${process.env.RUNNER_TEMP}/claude-execution-output.json`;
-
 /** Filename for the user request file, written by prompt generation */
 const USER_REQUEST_FILENAME = "claude-user-request.txt";
 
@@ -172,6 +171,7 @@ export async function runClaudeWithSdk(
     }
   } catch (error) {
     console.error("SDK execution error:", error);
+    await writeExecutionFile(messages);
     throw new Error(`SDK execution error: ${error}`);
   }
 
@@ -179,13 +179,9 @@ export async function runClaudeWithSdk(
     conclusion: "failure",
   };
 
-  // Write execution file
-  try {
-    await writeFile(EXECUTION_FILE, JSON.stringify(messages, null, 2));
-    console.log(`Log saved to ${EXECUTION_FILE}`);
-    result.executionFile = EXECUTION_FILE;
-  } catch (error) {
-    core.warning(`Failed to write execution file: ${error}`);
+  const executionFile = await writeExecutionFile(messages);
+  if (executionFile) {
+    result.executionFile = executionFile;
   }
 
   // Extract session_id from system.init message
diff --git a/base-action/test/execution-file.test.ts b/base-action/test/execution-file.test.ts
new file mode 100644
index 000000000..11b00f52d
--- /dev/null
+++ b/base-action/test/execution-file.test.ts
@@ -0,0 +1,39 @@
+#!/usr/bin/env bun
+
+import * as core from "@actions/core";
+import { afterEach, describe, expect, spyOn, test } from "bun:test";
+import { mkdtemp, rm, writeFile } from "fs/promises";
+import { tmpdir } from "os";
+import { join } from "path";
+import { setExecutionFileOutputIfPresent } from "../src/execution-file";
+
+describe("execution file output", () => {
+  const originalRunnerTemp = process.env.RUNNER_TEMP;
+  let tempDir: string | undefined;
+
+  afterEach(async () => {
+    if (tempDir) {
+      await rm(tempDir, { recursive: true, force: true });
+      tempDir = undefined;
+    }
+    process.env.RUNNER_TEMP = originalRunnerTemp;
+  });
+
+  test("sets execution_file output when the default execution file exists", async () => {
+    const setOutputSpy = spyOn(core, "setOutput").mockImplementation(() => {});
+    tempDir = await mkdtemp(join(tmpdir(), "claude-execution-file-"));
+    process.env.RUNNER_TEMP = tempDir;
+    const executionFile = join(tempDir, "claude-execution-output.json");
+    await writeFile(executionFile, "[]");
+
+    try {
+      expect(setExecutionFileOutputIfPresent()).toBe(executionFile);
+      expect(setOutputSpy).toHaveBeenCalledWith(
+        "execution_file",
+        executionFile,
+      );
+    } finally {
+      setOutputSpy.mockRestore();
+    }
+  });
+});
diff --git a/base-action/test/run-claude-sdk.test.ts b/base-action/test/run-claude-sdk.test.ts
new file mode 100644
index 000000000..877e88463
--- /dev/null
+++ b/base-action/test/run-claude-sdk.test.ts
@@ -0,0 +1,66 @@
+#!/usr/bin/env bun
+
+import { afterEach, describe, expect, mock, spyOn, test } from "bun:test";
+import { mkdtemp, readFile, rm, writeFile } from "fs/promises";
+import { tmpdir } from "os";
+import { join } from "path";
+
+describe("runClaudeWithSdk", () => {
+  const originalRunnerTemp = process.env.RUNNER_TEMP;
+  let tempDir: string | undefined;
+
+  afterEach(async () => {
+    if (tempDir) {
+      await rm(tempDir, { recursive: true, force: true });
+      tempDir = undefined;
+    }
+    process.env.RUNNER_TEMP = originalRunnerTemp;
+  });
+
+  test("writes the execution file when the SDK throws after yielding messages", async () => {
+    const consoleErrorSpy = spyOn(console, "error").mockImplementation(
+      () => {},
+    );
+    const consoleLogSpy = spyOn(console, "log").mockImplementation(() => {});
+
+    tempDir = await mkdtemp(join(tmpdir(), "claude-sdk-"));
+    process.env.RUNNER_TEMP = tempDir;
+
+    const promptPath = join(tempDir, "prompt.txt");
+    await writeFile(promptPath, "test prompt");
+
+    const initMessage = {
+      type: "system",
+      subtype: "init",
+      session_id: "session-123",
+      model: "claude-sonnet-4-6",
+    };
+
+    mock.module("@anthropic-ai/claude-agent-sdk", () => ({
+      query: async function* () {
+        yield initMessage;
+        throw new Error("Claude Code returned error_max_turns");
+      },
+    }));
+
+    try {
+      const { runClaudeWithSdk } = await import("../src/run-claude-sdk");
+
+      await expect(
+        runClaudeWithSdk(promptPath, {
+          sdkOptions: {},
+          showFullOutput: false,
+          hasJsonSchema: false,
+        }),
+      ).rejects.toThrow("SDK execution error");
+
+      const executionFile = join(tempDir, "claude-execution-output.json");
+      await expect(readFile(executionFile, "utf-8")).resolves.toBe(
+        JSON.stringify([initMessage], null, 2),
+      );
+    } finally {
+      consoleErrorSpy.mockRestore();
+      consoleLogSpy.mockRestore();
+    }
+  });
+});
diff --git a/src/entrypoints/run.ts b/src/entrypoints/run.ts
index c18ae2022..ffeb17c4c 100644
--- a/src/entrypoints/run.ts
+++ b/src/entrypoints/run.ts
@@ -40,6 +40,7 @@ import { installPlugins } from "../../base-action/src/install-plugins";
 import { preparePrompt } from "../../base-action/src/prepare-prompt";
 import { runClaude } from "../../base-action/src/run-claude";
 import type { ClaudeRunResult } from "../../base-action/src/run-claude-sdk";
+import { setExecutionFileOutputIfPresent } from "../../base-action/src/execution-file";
 
 /**
  * Install Claude Code CLI, handling retry logic and custom executable paths.
@@ -296,6 +297,7 @@ async function run() {
     core.setOutput("conclusion", claudeResult.conclusion);
   } catch (error) {
     const errorMessage = error instanceof Error ? error.message : String(error);
+    executionFile ??= setExecutionFileOutputIfPresent();
     // Only mark as prepare failure if we haven't completed the prepare phase
     if (!prepareCompleted) {
       prepareSuccess = false;