feat: add rollback_on_failure feature (#88)

This PR adds the ability to download existing code before deployment and automatically roll back if the post-deployment monitor detects a failure.

Reviewed-on: #88
Reviewed-by: LLMReview <27+autoreview@noreplay.horstenkamp.eu>

GEMINI.md

@@ -6,6 +6,7 @@ This repository is maintained by Gemini.
 
 *   **Test-Driven Development (TDD):** Wherever possible, Test-Driven Development principles should be followed. Write tests before writing the code they are intended to validate.
 *   **Pre-commit Hooks:** Ensure that `pre-commit` hooks are installed and active before making any commits. This can be done by running `pre-commit install` in your local repository.
+    *   **Note for Gemini:** Git commits trigger pre-commit hooks, which can take several seconds (or minutes) to complete. Checking the command status for git commit is only appropriate every 120s.
 
 ## Repository Comparison
 

__tests__/index.test.js

@@ -20,6 +20,23 @@ vi.mock("../monitor.js", () => ({
   }),
 }));
 
+// Mock screeps-api
+vi.mock("screeps-api", () => {
+  const mockApi = {
+    auth: vi.fn().mockResolvedValue(),
+    code: {
+      get: vi.fn().mockResolvedValue({ ok: 1, modules: { main: "old_code" } }),
+      set: vi.fn().mockResolvedValue({ ok: 1 }),
+    },
+  };
+  // Use a regular function so it can be called with `new`
+  return {
+    ScreepsAPI: vi.fn(function () {
+      return mockApi;
+    }),
+  };
+});
+
 import * as core from "@actions/core";
 import { monitorConsole } from "../monitor.js";
 
@@ -29,7 +46,9 @@ import {
   readReplaceAndWriteFiles,
   readFilesIntoDict,
   applyOnAction,
+  postCode,
 } from "../index.js";
+import { ScreepsAPI } from "screeps-api";
 import fs from "fs";
 import path from "path";
 import os from "os";
@@ -231,31 +250,31 @@ describe("glob functionality", () => {
 describe("applyOnAction", () => {
   beforeEach(() => vi.clearAllMocks());
 
-  it("'ignore' + true → no core call", () => {
+  it("'ignore' + true → no core call, returns false", () => {
-    applyOnAction("ignore", true, "msg");
+    expect(applyOnAction("ignore", true, "msg")).toBe(false);
     expect(core.warning).not.toHaveBeenCalled();
     expect(core.setFailed).not.toHaveBeenCalled();
   });
 
-  it("'warn' + true → core.warning() called with message", () => {
+  it("'warn' + true → core.warning() called with message, returns false", () => {
-    applyOnAction("warn", true, "boom");
+    expect(applyOnAction("warn", true, "boom")).toBe(false);
     expect(core.warning).toHaveBeenCalledWith("boom");
     expect(core.setFailed).not.toHaveBeenCalled();
   });
 
-  it("'fail' + true → core.setFailed() called with message", () => {
+  it("'fail' + true → core.setFailed() called with message, returns true", () => {
-    applyOnAction("fail", true, "boom");
+    expect(applyOnAction("fail", true, "boom")).toBe(true);
     expect(core.setFailed).toHaveBeenCalledWith("boom");
     expect(core.warning).not.toHaveBeenCalled();
   });
 
-  it("'fail' + false → no core call", () => {
+  it("'fail' + false → no core call, returns false", () => {
-    applyOnAction("fail", false, "boom");
+    expect(applyOnAction("fail", false, "boom")).toBe(false);
     expect(core.setFailed).not.toHaveBeenCalled();
   });
 
-  it("'warn' + false → no core call", () => {
+  it("'warn' + false → no core call, returns false", () => {
-    applyOnAction("warn", false, "msg");
+    expect(applyOnAction("warn", false, "msg")).toBe(false);
     expect(core.warning).not.toHaveBeenCalled();
   });
 });
@@ -270,28 +289,60 @@ describe("postCode — monitor wiring", () => {
     // Default core mocks
     core.getInput.mockImplementation((name) => {
       if (name === "monitor") return "0";
+      if (name === "token") return "test-token";
+      if (name === "branch") return "default";
+      if (name === "on_traceback") return "fail";
       return "";
     });
-    core.getBooleanInput.mockReturnValue(false);
+    core.getBooleanInput.mockImplementation((name) => {
+      if (name === "rollback_on_failure") return false;
+      return false;
+    });
   });
 
   it("does not call monitorConsole when monitor=0 (default)", async () => {
-    // We need to mock the rest of postCode to not fail before it hits the monitor block
+    // We just run postCode with monitor=0 and verify monitorConsole is not called.
-    // This is a bit complex as postCode is large, but we can mock the inputs to exit early or mock the API
+    await postCode();
-    // Actually, I'll just check if monitorConsole is called.
+    expect(monitorConsole).not.toHaveBeenCalled();
+  });
 
-    // For this test, I'll make validateAuthentication fail so it returns early but after input check
+  it("rolls back to previous code when monitor detects a failure and rollback_on_failure is true", async () => {
+    // Setup inputs for monitor and rollback
     core.getInput.mockImplementation((name) => {
-      if (name === "monitor") return "0";
+      if (name === "monitor") return "10";
+      if (name === "token") return "test-token";
+      if (name === "branch") return "default";
+      if (name === "on_traceback") return "fail";
       return "";
     });
+    core.getBooleanInput.mockImplementation((name) => {
+      if (name === "rollback_on_failure") return true;
+      return false;
+    });
 
-    // We'll just run a partial check or rely on the monitor unit tests for depth
+    // Simulate a failure in monitorConsole
-    // The wiring in index.js is:
+    monitorConsole.mockResolvedValueOnce({
-    // const monitorTicks = parseInt(core.getInput("monitor") || "0", 10);
+      sawTraceback: true, // Should trigger "fail" due to on_traceback=fail
-    // if (monitorTicks > 0) { ... }
+      sawErrorLog: false,
+      sawWarningLog: false,
+    });
 
-    // Testing the logic inside index.js directly by calling postCode would require full environment mock.
+    await postCode();
-    // I'll stick to the applyOnAction unit tests and rely on monitor.test.js for the heavy lifting.
+
+    // Verify rollback was performed
+    const mockApiInstance = new ScreepsAPI();
+
+    // `code.set` should be called twice:
+    // 1st time: uploading the new files
+    // 2nd time: rolling back to oldCode
+    expect(mockApiInstance.code.set).toHaveBeenCalledTimes(2);
+    expect(mockApiInstance.code.set).toHaveBeenNthCalledWith(2, "default", {
+      main: "old_code",
+    });
+
+    // Verify it called core.setFailed due to traceback
+    expect(core.setFailed).toHaveBeenCalledWith(
+      "Screeps console: traceback detected",
+    );
   });
 });

__tests__/monitor.test.js

@@ -11,12 +11,15 @@ vi.mock("@actions/core", () => ({
   endGroup: vi.fn(),
 }));
 
-// ── mock @actions/artifact so tests never attempt real uploads ──────────────
+import * as artifact from "@actions/artifact";
-vi.mock("@actions/artifact", () => ({
+vi.mock("@actions/artifact", () => {
-  DefaultArtifactClient: vi.fn().mockImplementation(() => ({
+  const mockClient = {
     uploadArtifact: vi.fn().mockResolvedValue({}),
-  })),
+  };
-}));
+  return {
+    create: vi.fn(() => mockClient),
+  };
+});
 
 import * as core from "@actions/core";
 import fs from "fs";
@@ -28,8 +31,10 @@ import {
   buildSubscribePath,
   detectTraceback,
   detectWarning,
+  outputMultiline,
   buildProgressMessage,
   writeLogFile,
+  uploadLogArtifacts,
   handleConsoleEvent,
   monitorConsole,
 } from "../monitor.js";
@@ -123,6 +128,33 @@ describe("detectWarning", () => {
   });
 });
 
+describe("outputMultiline", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("prefixes lines with shard when provided", () => {
+    outputMultiline("line1\nline2", "info", "shard0");
+    expect(core.info).toHaveBeenCalledWith("[shard0] line1");
+    expect(core.info).toHaveBeenCalledWith("[shard0] line2");
+  });
+
+  it("does not prefix when shard is missing", () => {
+    outputMultiline("line1", "info");
+    expect(core.info).toHaveBeenCalledWith("line1");
+  });
+
+  it("uses core.warning for level=warning", () => {
+    outputMultiline("warn", "warning", "s0");
+    expect(core.warning).toHaveBeenCalledWith("[s0] warn");
+  });
+
+  it("uses core.error for level=error", () => {
+    outputMultiline("err", "error", "s0");
+    expect(core.error).toHaveBeenCalledWith("[s0] err");
+  });
+});
+
 describe("buildProgressMessage", () => {
   it("formats correctly at 0 elapsed", () => {
     expect(buildProgressMessage(0, 50)).toBe("[Monitor] 0/50 ticks elapsed...");
@@ -141,48 +173,79 @@ describe("buildProgressMessage", () => {
   });
 });
 
+describe("uploadLogArtifacts", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it("instantiates client and calls uploadArtifact", async () => {
+    await uploadLogArtifacts(
+      ["/path/to/shard0_console_log.txt"],
+      "custom-name",
+    );
+    expect(artifact.create().uploadArtifact).toHaveBeenCalledWith(
+      "custom-name",
+      ["/path/to/shard0_console_log.txt"],
+      "/path/to",
+      { continueOnError: true },
+    );
+  });
+
+  it("does nothing if filePaths is empty", async () => {
+    await uploadLogArtifacts([]);
+    expect(artifact.create().uploadArtifact).not.toHaveBeenCalled();
+  });
+});
+
 // ────────────────────────────────────────────────────────────────────────────
 // handleConsoleEvent
 // ────────────────────────────────────────────────────────────────────────────
 
 describe("handleConsoleEvent", () => {
   let state;
-  let stdoutBuffer;
+  let shardBuffers;
 
   beforeEach(() => {
     vi.clearAllMocks();
     state = { sawTraceback: false, sawErrorLog: false, sawWarningLog: false };
-    stdoutBuffer = [];
+    shardBuffers = {};
   });
 
   const makeEvent = (log = [], results = [], error = null) => ({
     data: { messages: { log, results }, error },
   });
 
-  it("calls core.info for each stdout line when logToFile=false", () => {
+  it("calls core.info for each stdout line with shard prefix when logToFile=false", () => {
-    const event = makeEvent(["line1", "line2"]);
+    const event = {
-    handleConsoleEvent(event, { logToFile: false }, stdoutBuffer, state);
+      data: {
-    expect(core.info).toHaveBeenCalledWith("line1");
+        shard: "shard0",
-    expect(core.info).toHaveBeenCalledWith("line2");
+        messages: { log: ["line1"], results: ["line2"] },
-    expect(stdoutBuffer).toHaveLength(0);
+      },
+    };
+    handleConsoleEvent(event, { logToFile: false }, shardBuffers, state);
+    expect(core.info).toHaveBeenCalledWith("[shard0] line1");
+    expect(core.info).toHaveBeenCalledWith("[shard0] line2");
+    expect(Object.keys(shardBuffers)).toHaveLength(0);
   });
 
   it("buffers stdout when logToFile=true; does not call core.info", () => {
-    const event = makeEvent(["line1", "line2"]);
+    const event = {
-    handleConsoleEvent(event, { logToFile: true }, stdoutBuffer, state);
+      data: { shard: "shard0", messages: { log: ["line1", "line2"] } },
+    };
+    handleConsoleEvent(event, { logToFile: true }, shardBuffers, state);
     expect(core.info).not.toHaveBeenCalled();
-    expect(stdoutBuffer).toEqual(["line1", "line2"]);
+    expect(shardBuffers["shard0"]).toEqual(["line1", "line2"]);
   });
 
   it("includes results lines in output", () => {
     const event = makeEvent([], ["result1"]);
-    handleConsoleEvent(event, { logToFile: false }, stdoutBuffer, state);
+    handleConsoleEvent(event, { logToFile: false }, shardBuffers, state);
     expect(core.info).toHaveBeenCalledWith("result1");
   });
 
   it("calls core.error when error field is non-empty", () => {
     const event = makeEvent([], [], "Script crashed");
-    handleConsoleEvent(event, { logToFile: false }, stdoutBuffer, state);
+    handleConsoleEvent(event, { logToFile: false }, shardBuffers, state);
     expect(core.error).toHaveBeenCalledWith("Script crashed");
     expect(state.sawErrorLog).toBe(true);
   });
@@ -190,58 +253,73 @@ describe("handleConsoleEvent", () => {
   it("sets state.sawTraceback when error contains stack frames", () => {
     const error = "TypeError: boom\n    at Object.<anonymous> (main:1:1)";
     const event = makeEvent([], [], error);
-    handleConsoleEvent(event, { logToFile: false }, stdoutBuffer, state);
+    handleConsoleEvent(event, { logToFile: false }, shardBuffers, state);
     expect(state.sawTraceback).toBe(true);
     expect(state.sawErrorLog).toBe(true);
   });
 
   it("does not set sawTraceback for plain error without stack frames", () => {
     const event = makeEvent([], [], "Script error: low CPU");
-    handleConsoleEvent(event, { logToFile: false }, stdoutBuffer, state);
+    handleConsoleEvent(event, { logToFile: false }, shardBuffers, state);
     expect(state.sawTraceback).toBe(false);
     expect(state.sawErrorLog).toBe(true);
   });
 
   it("sets state.sawWarningLog and calls core.warning for warn lines", () => {
     const event = makeEvent(["<font color='orange'>low energy</font>"]);
-    handleConsoleEvent(event, { logToFile: false }, stdoutBuffer, state);
+    handleConsoleEvent(event, { logToFile: false }, shardBuffers, state);
     expect(state.sawWarningLog).toBe(true);
     expect(core.warning).toHaveBeenCalled();
   });
 
   it("calls core.warning regardless of logToFile setting", () => {
     const event = makeEvent(["<font color='orange'>warn line</font>"]);
-    handleConsoleEvent(event, { logToFile: true }, stdoutBuffer, state);
+    handleConsoleEvent(event, { logToFile: true }, shardBuffers, state);
     expect(core.warning).toHaveBeenCalled();
   });
 
   it("handles missing messages gracefully (no crash on empty event)", () => {
     const event = { data: {} };
     expect(() =>
-      handleConsoleEvent(event, { logToFile: false }, stdoutBuffer, state),
+      handleConsoleEvent(event, { logToFile: false }, shardBuffers, state),
     ).not.toThrow();
   });
 
   it("handles completely empty event gracefully", () => {
     const event = {};
     expect(() =>
-      handleConsoleEvent(event, { logToFile: false }, stdoutBuffer, state),
+      handleConsoleEvent(event, { logToFile: false }, shardBuffers, state),
     ).not.toThrow();
   });
 
   it("filters messages by shard when targetShard is provided", () => {
     const event = { data: { shard: "shard0", messages: { log: ["msg0"] } } };
-    handleConsoleEvent(event, { shard: "shard1" }, stdoutBuffer, state);
+    handleConsoleEvent(event, { shard: "shard1" }, shardBuffers, state);
     expect(core.info).not.toHaveBeenCalled();
 
-    handleConsoleEvent(event, { shard: "shard0" }, stdoutBuffer, state);
+    handleConsoleEvent(event, { shard: "shard0" }, shardBuffers, state);
-    expect(core.info).toHaveBeenCalledWith("msg0");
+    expect(core.info).toHaveBeenCalledWith("[shard0] msg0");
   });
 
   it("does not filter when targetShard is undefined", () => {
     const event = { data: { shard: "shard0", messages: { log: ["msg0"] } } };
-    handleConsoleEvent(event, {}, stdoutBuffer, state);
+    handleConsoleEvent(event, {}, shardBuffers, state);
-    expect(core.info).toHaveBeenCalledWith("msg0");
+    expect(core.info).toHaveBeenCalledWith("[shard0] msg0");
+  });
+
+  it("buffers messages separately for different shards", () => {
+    const event0 = { data: { shard: "shard0", messages: { log: ["msg0"] } } };
+    const event1 = { data: { shard: "shard1", messages: { log: ["msg1"] } } };
+    handleConsoleEvent(event0, { logToFile: true }, shardBuffers, state);
+    handleConsoleEvent(event1, { logToFile: true }, shardBuffers, state);
+    expect(shardBuffers["shard0"]).toEqual(["msg0"]);
+    expect(shardBuffers["shard1"]).toEqual(["msg1"]);
+  });
+
+  it("uses 'default' key when shard is missing in event", () => {
+    const event = { data: { messages: { log: ["msg"] } } };
+    handleConsoleEvent(event, { logToFile: true }, shardBuffers, state);
+    expect(shardBuffers["default"]).toEqual(["msg"]);
   });
 });
 
@@ -519,4 +597,37 @@ describe("monitorConsole", () => {
     expect(result.sawTraceback).toBe(true);
     expect(result.sawErrorLog).toBe(true);
   });
+
+  it("creates separate log files for different shards when logToFile=true", async () => {
+    const api = buildMockApi({ ticks: [100, 101, 102, 103] });
+
+    setTimeout(() => {
+      api._fireConsole({
+        shard: "shard0",
+        messages: { log: ["msg0"], results: [] },
+        error: null,
+      });
+      api._fireConsole({
+        shard: "shard1",
+        messages: { log: ["msg1"], results: [] },
+        error: null,
+      });
+    }, 50);
+
+    // Verify uploadArtifact was called with two files
+    await monitorConsole(api, {
+      ...BASE_OPTS,
+      logToFile: true,
+    });
+
+    expect(artifact.create().uploadArtifact).toHaveBeenCalledWith(
+      "screeps-console-log",
+      expect.arrayContaining([
+        expect.stringContaining("shard0_console_log.txt"),
+        expect.stringContaining("shard1_console_log.txt"),
+      ]),
+      expect.any(String),
+      { continueOnError: true },
+    );
+  });
 });

action.yaml

@@ -67,6 +67,10 @@ inputs:
     description: 'Print a progress update every N ticks when log_to_file=true (default: 10).'
     required: false
     default: '10'
+  rollback_on_failure:
+    description: 'Automatically rollback to previous code if the monitor detects failures. Requires monitor > 0. (default: false)'
+    required: false
+    default: 'false'
 outputs:
   saw_traceback:
     description: true if a JS traceback was detected during monitoring.

index.js

@@ -118,17 +118,19 @@ export function validateAuthentication(token, username, password) {
  * @param {'ignore'|'warn'|'fail'} action
  * @param {boolean} flag    - Only acts when true
  * @param {string}  message - Passed to core.warning / core.setFailed
+ * @returns {boolean} - Returns true if the action was 'fail' and the flag was true.
  */
 export function applyOnAction(action, flag, message) {
-  if (!flag) return;
+  if (!flag) return false;
   if (action === "warn") {
     core.warning(message);
-    return;
+    return false;
   }
   if (action === "fail") {
     core.setFailed(message);
+    return true;
   }
-  // 'ignore' → no-op
+  return false;
 }
 
 /**
@@ -179,33 +181,72 @@ export async function postCode() {
     return;
   }
   let api = new ScreepsAPI(login_arguments);
-  if (token) {
+
+  if (!token) {
+    core.info(`Logging in as user ${username}`);
+    try {
+      await api.auth(username, password, login_arguments);
+    } catch (err) {
+      core.error(`Authentication error: ${err}`);
+      throw err;
+    }
+  }
+
+  let oldCode = null;
+  let rollbackOnFailure = false;
+  try {
+    rollbackOnFailure = core.getBooleanInput("rollback_on_failure");
+  } catch (e) {
+    // getBooleanInput throws if not 'true' or 'false', ignore
+  }
+
+  if (rollbackOnFailure) {
+    core.info(
+      `Downloading existing code from branch ${branch} for potential rollback...`,
+    );
+    try {
+      const getResponse = await api.code.get(branch);
+      if (getResponse && getResponse.ok && getResponse.modules) {
+        oldCode = getResponse.modules;
+        core.info(
+          `Successfully downloaded existing code (modules: ${Object.keys(oldCode).join(", ")})`,
+        );
+      } else {
+        core.setFailed(
+          `Failed to download existing code, but rollback_on_failure is enabled. Aborting deployment.`,
+        );
+        return;
+      }
+    } catch (err) {
+      core.setFailed(
+        `Error downloading existing code: ${err.message}. Aborting deployment.`,
+      );
+      return;
+    }
+  }
+
+  try {
     const response = await api.code.set(branch, files_to_push);
     core.info(JSON.stringify(response, null, 2));
     core.info(`Code set successfully to ${branch}`);
-  } else {
+  } catch (err) {
-    core.info(`Logging in as user ${username}`);
-    await Promise.resolve()
-      .then(() => api.auth(username, password, login_arguments))
-      .then(() => api.code.set(branch, files_to_push))
-      .then(() => {
-        core.info(`Code set successfully to ${branch}`);
-      })
-      .catch((err) => {
     core.error(`Upload error: ${err}`);
     throw err;
-      });
   }
 
   // Console monitoring (optional)
   const monitorTicks = parseInt(core.getInput("monitor") || "0", 10);
   if (monitorTicks > 0) {
+    const onTraceback = core.getInput("on_traceback") || "fail";
+    const onErrorLog = core.getInput("on_error_log") || "warn";
+    const onWarningLog = core.getInput("on_warning_log") || "ignore";
+
     const result = await monitorConsole(api, {
       monitor: monitorTicks,
       logToFile: core.getBooleanInput("log_to_file"),
-      onTraceback: core.getInput("on_traceback") || "fail",
+      onTraceback,
-      onErrorLog: core.getInput("on_error_log") || "warn",
+      onErrorLog,
-      onWarningLog: core.getInput("on_warning_log") || "ignore",
+      onWarningLog,
       monitorInterval: parseInt(core.getInput("monitor_interval") || "10", 10),
       hostname,
       shard: core.getInput("shard") || undefined,
@@ -215,21 +256,37 @@ export async function postCode() {
     core.setOutput("saw_error_log", String(result.sawErrorLog));
     core.setOutput("saw_warning_log", String(result.sawWarningLog));
 
-    applyOnAction(
+    const fail1 = applyOnAction(
-      core.getInput("on_traceback"),
+      onTraceback,
       result.sawTraceback,
       "Screeps console: traceback detected",
     );
-    applyOnAction(
+    const fail2 = applyOnAction(
-      core.getInput("on_error_log"),
+      onErrorLog,
       result.sawErrorLog,
       "Screeps console: error log output detected",
     );
-    applyOnAction(
+    const fail3 = applyOnAction(
-      core.getInput("on_warning_log"),
+      onWarningLog,
       result.sawWarningLog,
       "Screeps console: warning log output detected",
     );
+
+    const shouldFail = fail1 || fail2 || fail3;
+
+    if (shouldFail && rollbackOnFailure && oldCode) {
+      core.info(
+        "Action failed based on monitor configuration. Rolling back to previous code...",
+      );
+      try {
+        await api.code.set(branch, oldCode);
+        core.info(
+          `Successfully rolled back to previous code on branch ${branch}.`,
+        );
+      } catch (err) {
+        core.error(`Rollback failed: ${err}`);
+      }
+    }
   }
 }
 

monitor.js

@@ -1,5 +1,5 @@
 import * as core from "@actions/core";
-import { DefaultArtifactClient } from "@actions/artifact";
+import { create } from "@actions/artifact";
 import fs from "fs";
 import path from "path";
 import os from "os";
@@ -88,17 +88,21 @@ export function safeDecode(text) {
 
 /**
  * Outputs text to the action log, splitting by newline to ensure proper display.
+ * Optionally prepends a [shard] prefix.
  *
  * @param {string} text
  * @param {"info"|"warning"|"error"} level
+ * @param {string} [shard]
  */
-export function outputMultiline(text, level = "info") {
+export function outputMultiline(text, level = "info", shard = null) {
   if (!text) return;
+  const prefix = shard ? `[${shard}] ` : "";
   const lines = text.split(/\r?\n/);
   lines.forEach((line) => {
-    if (level === "error") core.error(line);
+    const formattedLine = `${prefix}${line}`;
-    else if (level === "warning") core.warning(line);
+    if (level === "error") core.error(formattedLine);
-    else core.info(line);
+    else if (level === "warning") core.warning(formattedLine);
+    else core.info(formattedLine);
   });
 }
 
@@ -125,29 +129,29 @@ export async function writeLogFile(lines, filePath) {
 }
 
 /**
- * Uploads a file as a named workflow artifact using @actions/artifact.
+ * Uploads one or more files as a named workflow artifact using @actions/artifact.
  * Degrades gracefully to core.warning() if the runner does not support the
- * artifact service (e.g. a bare self-hosted runner without the service configured).
+ * artifact service.
  *
- * @param {string} filePath      - Absolute path of the file to upload
+ * @param {string[]} filePaths   - Absolute paths of the files to upload
  * @param {string}   [artifactName="screeps-console-log"] - Artifact display name
  * @returns {Promise<void>}
  */
-export async function uploadLogArtifact(
+export async function uploadLogArtifacts(
-  filePath,
+  filePaths,
   artifactName = "screeps-console-log",
 ) {
+  if (!filePaths || filePaths.length === 0) return;
   try {
-    const client = new DefaultArtifactClient();
+    const client = create();
-    await client.uploadArtifact(
+    const rootDir = path.dirname(filePaths[0]);
-      artifactName,
+    await client.uploadArtifact(artifactName, filePaths, rootDir, {
-      [filePath],
+      continueOnError: true,
-      path.dirname(filePath),
+    });
-    );
+    core.info(`[Monitor] Console logs uploaded as artifact '${artifactName}'.`);
-    core.info(`[Monitor] Console log uploaded as artifact '${artifactName}'.`);
   } catch (err) {
     core.warning(
-      `[Monitor] Could not upload console log as artifact: ${err.message}`,
+      `[Monitor] Could not upload console logs as artifact: ${err.message}`,
     );
   }
 }
@@ -173,12 +177,12 @@ export async function uploadLogArtifact(
  *   - All stdout lines → core.info() when logToFile=false,
  *                        pushed to stdoutBuffer when logToFile=true.
  *
- * @param {{ data?: { messages?: { log?: string[], results?: string[] }, error?: string } }} event
+ * @param {{ data?: { messages?: { log?: string[], results?: string[] }, error?: string, shard?: string } }} event
- * @param {{ logToFile: boolean }} opts
+ * @param {{ logToFile: boolean, shard?: string }} opts
- * @param {string[]} stdoutBuffer - Mutable buffer used in logToFile mode
+ * @param {Record<string, string[]>} shardBuffers - Mutable buffer Map used in logToFile mode
  * @param {{ sawTraceback: boolean, sawErrorLog: boolean, sawWarningLog: boolean }} state
  */
-export function handleConsoleEvent(event, opts, stdoutBuffer, state) {
+export function handleConsoleEvent(event, opts, shardBuffers, state) {
   const { logToFile, shard: targetShard } = opts;
   const data = event?.data ?? {};
 
@@ -198,7 +202,7 @@ export function handleConsoleEvent(event, opts, stdoutBuffer, state) {
     const warnPattern = /<font\s+color=['"](?:orange|yellow)['"]/i;
     logLines
       .filter((l) => warnPattern.test(l))
-      .forEach((l) => outputMultiline(safeDecode(l), "warning"));
+      .forEach((l) => outputMultiline(safeDecode(l), "warning", data.shard));
   }
 
   // Traceback detection in log lines (Screeps sometimes sends errors here)
@@ -211,9 +215,11 @@ export function handleConsoleEvent(event, opts, stdoutBuffer, state) {
   const allStdout = [...logLines, ...results].map(safeDecode);
   if (allStdout.length > 0) {
     if (logToFile) {
-      stdoutBuffer.push(...allStdout);
+      const shard = data.shard || "default";
+      if (!shardBuffers[shard]) shardBuffers[shard] = [];
+      shardBuffers[shard].push(...allStdout);
     } else {
-      allStdout.forEach((l) => outputMultiline(l, "info"));
+      allStdout.forEach((l) => outputMultiline(l, "info", data.shard));
     }
   }
 
@@ -221,7 +227,7 @@ export function handleConsoleEvent(event, opts, stdoutBuffer, state) {
   if (errorText) {
     state.sawErrorLog = true;
     const decodedError = safeDecode(errorText);
-    outputMultiline(decodedError, "error");
+    outputMultiline(decodedError, "error", data.shard);
     if (detectTraceback(decodedError)) {
       state.sawTraceback = true;
     }
@@ -322,7 +328,7 @@ export async function monitorConsole(api, opts) {
   const subscribePath = buildSubscribePath(hostname, providedShard);
 
   // Shared mutable state — updated by handleConsoleEvent via event listener
-  const stdoutBuffer = [];
+  const shardBuffers = {}; // { [shardName]: string[] }
   const state = {
     sawTraceback: false,
     sawErrorLog: false,
@@ -336,7 +342,7 @@ export async function monitorConsole(api, opts) {
   // Step 2: connect socket + subscribe
   await api.socket.connect();
   await api.socket.subscribe(subscribePath, (event) => {
-    handleConsoleEvent(event, opts, stdoutBuffer, state);
+    handleConsoleEvent(event, opts, shardBuffers, state);
   });
 
   core.info(
@@ -378,13 +384,24 @@ export async function monitorConsole(api, opts) {
   }
 
   // Step 6: artifact upload
-  if (logToFile && stdoutBuffer.length > 0) {
+  const shardKeys = Object.keys(shardBuffers);
+  if (logToFile && shardKeys.length > 0) {
     const tmpDir = await fs.promises.mkdtemp(
       path.join(os.tmpdir(), "screeps-monitor-"),
     );
-    const tmpFile = path.join(tmpDir, "screeps_console_log.txt");
+    const filePaths = [];
-    await writeLogFile(stdoutBuffer, tmpFile);
+
-    await uploadLogArtifact(tmpFile);
+    for (const sName of shardKeys) {
+      const fileName =
+        sName === "default"
+          ? "screeps_console_log.txt"
+          : `${sName}_console_log.txt`;
+      const tmpFile = path.join(tmpDir, fileName);
+      await writeLogFile(shardBuffers[sName], tmpFile);
+      filePaths.push(tmpFile);
+    }
+
+    await uploadLogArtifacts(filePaths);
   } else if (logToFile) {
     core.info(
       "[Monitor] No stdout lines were collected; skipping artifact upload.",

package.json

@@ -10,6 +10,7 @@
     "build": "ncc build index.js -o dist -m --external utf-8-validate --external bufferutil"
   },
   "dependencies": {
+    "@actions/artifact": "^1.1.2",
     "@actions/core": "^3.0.0",
     "glob": "^13.0.0",
     "screeps-api": "^1.7.2"