diff --git a/src/handlers/eval/config-bundle/config-bundle.test.tsx b/src/handlers/eval/config-bundle/config-bundle.test.tsx
index 1e9172fa1..d7c260e97 100644
--- a/src/handlers/eval/config-bundle/config-bundle.test.tsx
+++ b/src/handlers/eval/config-bundle/config-bundle.test.tsx
@@ -10,7 +10,7 @@ import {
   testIO,
 } from "../../../testing";
 import { createRootHandler } from "../../index";
-import type { UpdateConfigurationBundleInput } from "../types";
+import type { CreateConfigurationBundleInput, UpdateConfigurationBundleInput } from "../types";
 
 const REGION = "us-west-2";
 const COMPONENT_ARN =
@@ -97,7 +97,7 @@ describe("eval config-bundle command hierarchy", () => {
         .find((child) => child.name() === "create")
         ?.flags()
         .map((candidate) => candidate.name),
-    ).toEqual(["name", "components", "kms-key-arn"]);
+    ).toEqual(["name", "components", "branch-name", "commit-message", "kms-key-arn"]);
     expect(
       configBundle
         ?.children()
@@ -164,6 +164,34 @@ describe("eval config-bundle command hierarchy", () => {
 });
 
 describe("config-bundle create", () => {
+  test("passes branch name, commit message, and KMS key", async () => {
+    const { core, route } = testConfigBundleCommand();
+
+    await route([
+      "eval",
+      "config-bundle",
+      "create",
+      "--name",
+      "orders-prompt",
+      "--components",
+      JSON.stringify(COMPONENTS),
+      "--branch-name",
+      "feature/order-routing",
+      "--commit-message",
+      "Add order routing configuration",
+      "--kms-key-arn",
+      "arn:aws:kms:us-west-2:123456789012:key/initial",
+    ]);
+
+    expect(callArgs(core, "createConfigurationBundle")[0]).toEqual({
+      bundleName: "orders-prompt",
+      components: COMPONENTS,
+      branchName: "feature/order-routing",
+      commitMessage: "Add order routing configuration",
+      kmsKeyArn: "arn:aws:kms:us-west-2:123456789012:key/initial",
+    } satisfies CreateConfigurationBundleInput);
+  });
+
   test("reads components from stdin", async () => {
     const { core, route } = testConfigBundleCommand(JSON.stringify(COMPONENTS));
 
@@ -182,6 +210,25 @@ describe("config-bundle create", () => {
     });
   });
 
+  test("rejects a branch name that does not match service constraints", async () => {
+    const { core, route } = testConfigBundleCommand();
+
+    await expect(
+      route([
+        "eval",
+        "config-bundle",
+        "create",
+        "--name",
+        "orders-prompt",
+        "--components",
+        JSON.stringify(COMPONENTS),
+        "--branch-name",
+        "1-invalid",
+      ]),
+    ).rejects.toThrow(/Invalid value for option '--branch-name'/);
+    expect(core.eval.calls).toHaveLength(0);
+  });
+
   test.each([
     ["an empty map", {}],
     ["a component without configuration", { [COMPONENT_ARN]: {} }],
diff --git a/src/handlers/eval/config-bundle/create/index.tsx b/src/handlers/eval/config-bundle/create/index.tsx
index 784596468..098a4c231 100644
--- a/src/handlers/eval/config-bundle/create/index.tsx
+++ b/src/handlers/eval/config-bundle/create/index.tsx
@@ -7,6 +7,13 @@ import type { Core } from "../../../types";
 import { coreOptsFromCtx } from "../../../utils";
 import { resolveConfigurationBundleComponents } from "../components";
 
+const BranchNameSchema = z
+  .string()
+  .min(1)
+  .max(128)
+  .regex(/^[a-zA-Z][a-zA-Z0-9_/-]{0,127}$/, "Value must match [a-zA-Z][a-zA-Z0-9_/-]");
+const CommitMessageSchema = z.string().max(500);
+
 export const createCreateConfigBundleHandler = (core: Core, io: AppIO) =>
   createHandler({
     name: "create",
@@ -19,6 +26,12 @@ export const createCreateConfigBundleHandler = (core: Core, io: AppIO) =>
         z.string().optional(),
         { sensitive: true },
       ),
+      flag("branch-name", "branch name for the initial configuration", BranchNameSchema.optional()),
+      flag(
+        "commit-message",
+        "message describing the initial configuration",
+        CommitMessageSchema.optional(),
+      ),
       flag(
         "kms-key-arn",
         "customer managed KMS key ARN for component configurations",
@@ -42,6 +55,8 @@ export const createCreateConfigBundleHandler = (core: Core, io: AppIO) =>
           {
             bundleName: flags["name"],
             components,
+            branchName: flags["branch-name"],
+            commitMessage: flags["commit-message"],
             kmsKeyArn: flags["kms-key-arn"],
           },
           coreOptsFromCtx(ctx),
diff --git a/src/handlers/eval/types.tsx b/src/handlers/eval/types.tsx
index 278f8f34c..226c17f81 100644
--- a/src/handlers/eval/types.tsx
+++ b/src/handlers/eval/types.tsx
@@ -185,7 +185,7 @@ export type RoleScopeWarning = {
 export type CreateDatasetInput = CreateDatasetRequest;
 export type CreateConfigurationBundleInput = Pick<
   CreateConfigurationBundleRequest,
-  "bundleName" | "components" | "kmsKeyArn"
+  "bundleName" | "components" | "branchName" | "commitMessage" | "kmsKeyArn"
 >;
 export type UpdateConfigurationBundleInput = Required<
   Pick<UpdateConfigurationBundleRequest, "components" | "commitMessage" | "branchName">
diff --git a/src/projectSchemas/config-bundle.test.ts b/src/projectSchemas/config-bundle.test.ts
new file mode 100644
index 000000000..71edf0d60
--- /dev/null
+++ b/src/projectSchemas/config-bundle.test.ts
@@ -0,0 +1,23 @@
+import { describe, expect, test } from "bun:test";
+import { ConfigBundleBranchNameSchema } from "./config-bundle";
+
+describe("ConfigBundleBranchNameSchema", () => {
+  test.each(["mainline", "feature/order-routing", "release-2026_08"])(
+    "accepts service-compatible branch name %s",
+    (branchName) => {
+      expect(ConfigBundleBranchNameSchema.safeParse(branchName).success).toBe(true);
+    },
+  );
+
+  test.each(["", "1-mainline", "feature branch", "feature.order"])(
+    "rejects service-incompatible branch name %s",
+    (branchName) => {
+      expect(ConfigBundleBranchNameSchema.safeParse(branchName).success).toBe(false);
+    },
+  );
+
+  test("enforces the service's 128-character maximum", () => {
+    expect(ConfigBundleBranchNameSchema.safeParse(`a${"b".repeat(127)}`).success).toBe(true);
+    expect(ConfigBundleBranchNameSchema.safeParse(`a${"b".repeat(128)}`).success).toBe(false);
+  });
+});
diff --git a/src/projectSchemas/config-bundle.ts b/src/projectSchemas/config-bundle.ts
index 74a219124..d32baf351 100644
--- a/src/projectSchemas/config-bundle.ts
+++ b/src/projectSchemas/config-bundle.ts
@@ -15,7 +15,11 @@ export const ComponentConfigurationSchema = z.object({
 export type ComponentConfiguration = z.infer<typeof ComponentConfigurationSchema>;
 export const ComponentConfigurationMapSchema = z.record(z.string(), ComponentConfigurationSchema);
 export type ComponentConfigurationMap = z.infer<typeof ComponentConfigurationMapSchema>;
-export const ConfigBundleBranchNameSchema = z.string().max(128);
+export const ConfigBundleBranchNameSchema = z
+  .string()
+  .min(1)
+  .max(128)
+  .regex(/^[a-zA-Z][a-zA-Z0-9_/-]{0,127}$/, "Value must match [a-zA-Z][a-zA-Z0-9_/-]");
 export const ConfigBundleCommitMessageSchema = z.string().max(500);
 export const ConfigBundleSchema = z.object({
   name: ConfigBundleNameSchema,