diff --git a/actions/setup/js/dispatch_repository.cjs b/actions/setup/js/dispatch_repository.cjs
index a59e9132af2..6dfc1034384 100644
--- a/actions/setup/js/dispatch_repository.cjs
+++ b/actions/setup/js/dispatch_repository.cjs
@@ -14,6 +14,7 @@ const { parseRepoSlug, validateTargetRepo, parseAllowedRepos } = require("./repo
 const { logStagedPreviewInfo } = require("./staged_preview.cjs");
 const { isStagedMode } = require("./safe_output_helpers.cjs");
 const { buildAwContext } = require("./aw_context.cjs");
+const { SAFE_OUTPUT_E001, SAFE_OUTPUT_E099 } = require("./error_codes.cjs");
 
 /**
  * Main handler factory for dispatch_repository
@@ -45,7 +46,7 @@ async function main(config = {}) {
       core.warning("dispatch_repository: tool_name is empty, skipping");
       return {
         success: false,
-        error: "E001: tool_name is required",
+        error: `${SAFE_OUTPUT_E001}: tool_name is required`,
       };
     }
 
@@ -55,7 +56,7 @@ async function main(config = {}) {
       core.warning(`dispatch_repository: unknown tool "${toolName}", skipping`);
       return {
         success: false,
-        error: `E001: tool "${toolName}" is not configured in dispatch_repository`,
+        error: `${SAFE_OUTPUT_E001}: tool "${toolName}" is not configured in dispatch_repository`,
       };
     }
 
@@ -88,7 +89,7 @@ async function main(config = {}) {
       core.warning(`dispatch_repository: no target repository for tool "${toolName}"`);
       return {
         success: false,
-        error: `E001: No target repository configured for tool "${toolName}"`,
+        error: `${SAFE_OUTPUT_E001}: No target repository configured for tool "${toolName}"`,
       };
     }
 
@@ -110,7 +111,7 @@ async function main(config = {}) {
       core.warning(`dispatch_repository: invalid repository slug "${targetRepoSlug}"`);
       return {
         success: false,
-        error: `E001: Invalid repository slug "${targetRepoSlug}" (expected "owner/repo")`,
+        error: `${SAFE_OUTPUT_E001}: Invalid repository slug "${targetRepoSlug}" (expected "owner/repo")`,
       };
     }
 
@@ -118,14 +119,9 @@ async function main(config = {}) {
     /** @type {Record<string, any>} */
     const clientPayload = {
       workflow: toolConfig.workflow || "",
+      ...(message.inputs && typeof message.inputs === "object" ? message.inputs : {}),
     };
 
-    if (message.inputs && typeof message.inputs === "object") {
-      for (const [key, value] of Object.entries(message.inputs)) {
-        clientPayload[key] = value;
-      }
-    }
-
     // Inject aw_context so the receiving repository can trace the dispatch back to its caller.
     clientPayload["aw_context"] = buildAwContext();
 
@@ -178,7 +174,7 @@ async function main(config = {}) {
 
       return {
         success: false,
-        error: `E099: Failed to dispatch repository_dispatch event "${eventType}" to ${targetRepoSlug}: ${errorMessage}`,
+        error: `${SAFE_OUTPUT_E099}: Failed to dispatch repository_dispatch event "${eventType}" to ${targetRepoSlug}: ${errorMessage}`,
       };
     }
   };
diff --git a/actions/setup/js/dispatch_repository.test.cjs b/actions/setup/js/dispatch_repository.test.cjs
new file mode 100644
index 00000000000..77eac4136cb
--- /dev/null
+++ b/actions/setup/js/dispatch_repository.test.cjs
@@ -0,0 +1,263 @@
+// @ts-check
+import { describe, it, expect, beforeEach, afterEach, vi } from "vitest";
+
+const { main } = require("./dispatch_repository.cjs");
+
+describe("dispatch_repository", () => {
+  /** @type {any} */
+  let mockCore;
+  /** @type {any} */
+  let mockGithub;
+  /** @type {any} */
+  let mockContext;
+
+  /** @type {any} */
+  let dispatchEventCalls;
+
+  /** @type {{ core: any, github: any, context: any }} */
+  let savedGlobals;
+
+  beforeEach(() => {
+    savedGlobals = {
+      core: global.core,
+      github: global.github,
+      context: global.context,
+    };
+
+    dispatchEventCalls = [];
+
+    mockCore = {
+      infos: /** @type {string[]} */ [],
+      warnings: /** @type {string[]} */ [],
+      errors: /** @type {string[]} */ [],
+      info: /** @param {string} msg */ msg => mockCore.infos.push(msg),
+      warning: /** @param {string} msg */ msg => mockCore.warnings.push(msg),
+      error: /** @param {string} msg */ msg => mockCore.errors.push(msg),
+    };
+
+    mockGithub = {
+      rest: {
+        repos: {
+          createDispatchEvent: /** @param {any} params */ async params => {
+            dispatchEventCalls.push(params);
+            return { data: {} };
+          },
+        },
+      },
+    };
+
+    mockContext = {
+      runId: 9999,
+      repo: { owner: "test-owner", repo: "test-repo" },
+      payload: {},
+    };
+
+    global.core = mockCore;
+    global.github = mockGithub;
+    global.context = mockContext;
+  });
+
+  afterEach(() => {
+    global.core = savedGlobals.core;
+    global.github = savedGlobals.github;
+    global.context = savedGlobals.context;
+    vi.restoreAllMocks();
+  });
+
+  describe("main factory", () => {
+    it("should return a handler function", async () => {
+      const handler = await main({ tools: {} });
+      expect(typeof handler).toBe("function");
+    });
+
+    it("should return a handler function with no config", async () => {
+      const handler = await main();
+      expect(typeof handler).toBe("function");
+    });
+
+    it("should log initialization info", async () => {
+      await main({ tools: { deploy: { event_type: "deploy", max: 2 } } });
+      expect(mockCore.infos.some(/** @param {string} m */ m => m.includes("dispatch_repository handler initialized"))).toBe(true);
+    });
+  });
+
+  describe("handleDispatchRepository", () => {
+    it("should return error when tool_name is missing", async () => {
+      const handler = await main({ tools: {} });
+      const result = await handler({ tool_name: "" }, {});
+      expect(result.success).toBe(false);
+      expect(result.error).toMatch(/tool_name is required/);
+    });
+
+    it("should return error when tool_name is whitespace-only", async () => {
+      const handler = await main({ tools: {} });
+      const result = await handler({ tool_name: "   " }, {});
+      expect(result.success).toBe(false);
+      expect(result.error).toMatch(/tool_name is required/);
+    });
+
+    it("should return error when tool is not configured", async () => {
+      const handler = await main({ tools: {} });
+      const result = await handler({ tool_name: "unknown_tool" }, {});
+      expect(result.success).toBe(false);
+      expect(result.error).toMatch(/not configured/);
+    });
+
+    it("should return error when max count is reached", async () => {
+      const handler = await main({
+        tools: {
+          deploy: { event_type: "deploy", repository: "test-owner/test-repo", max: 1 },
+        },
+      });
+
+      // First dispatch succeeds
+      const first = await handler({ tool_name: "deploy" }, {});
+      expect(first.success).toBe(true);
+
+      // Second dispatch hits the limit
+      const second = await handler({ tool_name: "deploy" }, {});
+      expect(second.success).toBe(false);
+      expect(second.error).toMatch(/Max count/);
+    });
+
+    it("should return error when no target repository is configured", async () => {
+      const handler = await main({
+        tools: { deploy: { event_type: "deploy" } },
+      });
+      const result = await handler({ tool_name: "deploy" }, {});
+      expect(result.success).toBe(false);
+      expect(result.error).toMatch(/No target repository/);
+    });
+
+    it("should return error when repository slug is invalid", async () => {
+      const handler = await main({
+        tools: { deploy: { event_type: "deploy", repository: "not-valid-slug" } },
+      });
+      const result = await handler({ tool_name: "deploy" }, {});
+      expect(result.success).toBe(false);
+      expect(result.error).toMatch(/Invalid repository slug/);
+    });
+
+    it("should return error when event_type is not configured", async () => {
+      const handler = await main({
+        tools: { deploy: { repository: "test-owner/test-repo" } },
+      });
+      const result = await handler({ tool_name: "deploy" }, {});
+      expect(result.success).toBe(false);
+      expect(result.error).toMatch(/event_type is required/);
+    });
+
+    it("should dispatch successfully with valid config", async () => {
+      const handler = await main({
+        tools: {
+          deploy: { event_type: "deploy", repository: "test-owner/other-repo", max: 2 },
+        },
+      });
+
+      const result = await handler({ tool_name: "deploy" }, {});
+      expect(result.success).toBe(true);
+      expect(result.tool_name).toBe("deploy");
+      expect(result.repository).toBe("test-owner/other-repo");
+      expect(result.event_type).toBe("deploy");
+      expect(dispatchEventCalls.length).toBe(1);
+      expect(dispatchEventCalls[0].event_type).toBe("deploy");
+    });
+
+    it("should include message inputs in client_payload", async () => {
+      const handler = await main({
+        tools: {
+          deploy: { event_type: "deploy", repository: "test-owner/test-repo", max: 5 },
+        },
+      });
+
+      await handler({ tool_name: "deploy", inputs: { env: "production", version: "1.2.3" } }, {});
+
+      expect(dispatchEventCalls.length).toBe(1);
+      expect(dispatchEventCalls[0].client_payload.env).toBe("production");
+      expect(dispatchEventCalls[0].client_payload.version).toBe("1.2.3");
+    });
+
+    it("should inject aw_context into client_payload", async () => {
+      const handler = await main({
+        tools: {
+          deploy: { event_type: "deploy", repository: "test-owner/test-repo", max: 5 },
+        },
+      });
+
+      await handler({ tool_name: "deploy" }, {});
+
+      expect(dispatchEventCalls.length).toBe(1);
+      expect(dispatchEventCalls[0].client_payload).toHaveProperty("aw_context");
+    });
+
+    it("should use message.repository over toolConfig.repository when both set", async () => {
+      const handler = await main({
+        tools: {
+          deploy: { event_type: "deploy", repository: "test-owner/default-repo", max: 5 },
+        },
+      });
+
+      const result = await handler({ tool_name: "deploy", repository: "test-owner/override-repo" }, {});
+
+      expect(result.success).toBe(true);
+      expect(result.repository).toBe("test-owner/override-repo");
+      expect(dispatchEventCalls[0].owner).toBe("test-owner");
+      expect(dispatchEventCalls[0].repo).toBe("override-repo");
+    });
+
+    it("should default to first allowed_repository when no target given", async () => {
+      const handler = await main({
+        tools: {
+          deploy: { event_type: "deploy", allowed_repositories: ["test-owner/allowed-repo"], max: 5 },
+        },
+      });
+
+      const result = await handler({ tool_name: "deploy" }, {});
+      expect(result.success).toBe(true);
+      expect(result.repository).toBe("test-owner/allowed-repo");
+    });
+
+    it("should return error on API failure", async () => {
+      mockGithub.rest.repos.createDispatchEvent = async () => {
+        throw new Error("API rate limit exceeded");
+      };
+
+      const handler = await main({
+        tools: { deploy: { event_type: "deploy", repository: "test-owner/test-repo", max: 5 } },
+      });
+
+      const result = await handler({ tool_name: "deploy" }, {});
+      expect(result.success).toBe(false);
+      expect(result.error).toMatch(/Failed to dispatch/);
+      expect(result.error).toMatch(/API rate limit exceeded/);
+    });
+
+    it("should return staged result when isStaged is true", async () => {
+      const handler = await main({
+        tools: { deploy: { event_type: "deploy", repository: "test-owner/test-repo", max: 5 } },
+        staged: true,
+      });
+
+      const result = await handler({ tool_name: "deploy" }, {});
+      expect(result.success).toBe(true);
+      expect(result.staged).toBe(true);
+      expect(dispatchEventCalls.length).toBe(0);
+    });
+
+    it("should parse numeric max from string config", async () => {
+      const handler = await main({
+        tools: { deploy: { event_type: "deploy", repository: "test-owner/test-repo", max: "3" } },
+      });
+
+      // Should allow up to 3 dispatches
+      for (let i = 0; i < 3; i++) {
+        const result = await handler({ tool_name: "deploy" }, {});
+        expect(result.success).toBe(true);
+      }
+
+      const overflow = await handler({ tool_name: "deploy" }, {});
+      expect(overflow.success).toBe(false);
+      expect(overflow.error).toMatch(/Max count of 3/);
+    });
+  });
+});