diff --git a/apps/server/src/resources/impls/git.test.ts b/apps/server/src/resources/impls/git.test.ts
index 9b6c9f5c..878d54cc 100644
--- a/apps/server/src/resources/impls/git.test.ts
+++ b/apps/server/src/resources/impls/git.test.ts
@@ -4,8 +4,48 @@ import path from 'node:path';
 import os from 'node:os';
 
 import { loadGitResource } from './git.ts';
+import { GitResourceSchema } from '../schema.ts';
 import type { BtcaGitResourceArgs } from '../types.ts';
 
+describe('Branch name validation', () => {
+	const validGitResource = (branch: string) => ({
+		type: 'git' as const,
+		name: 'test',
+		url: 'https://github.com/test/repo',
+		branch
+	});
+
+	it('accepts monorepo-style scoped tags', () => {
+		const result = GitResourceSchema.safeParse(validGitResource('@chakra-ui/react@2.8.2'));
+		expect(result.success).toBe(true);
+	});
+
+	it('accepts simple version tags', () => {
+		const result = GitResourceSchema.safeParse(validGitResource('v18.2.0'));
+		expect(result.success).toBe(true);
+	});
+
+	it('accepts standard branch names', () => {
+		const result = GitResourceSchema.safeParse(validGitResource('feature/my-branch'));
+		expect(result.success).toBe(true);
+	});
+
+	it('rejects branch names starting with hyphen', () => {
+		const result = GitResourceSchema.safeParse(validGitResource('-dangerous'));
+		expect(result.success).toBe(false);
+	});
+
+	it('rejects branch names with spaces', () => {
+		const result = GitResourceSchema.safeParse(validGitResource('my branch'));
+		expect(result.success).toBe(false);
+	});
+
+	it('rejects branch names with special characters', () => {
+		const result = GitResourceSchema.safeParse(validGitResource('branch;rm -rf'));
+		expect(result.success).toBe(false);
+	});
+});
+
 describe('Git Resource', () => {
 	let testDir: string;
 
@@ -101,6 +141,36 @@ describe('Git Resource', () => {
 			expect(loadGitResource(args)).rejects.toThrow('Branch name must contain only');
 		});
 
+		it('throws error for branch name starting with hyphen', async () => {
+			const args: BtcaGitResourceArgs = {
+				type: 'git',
+				name: 'hyphen-branch',
+				url: 'https://github.com/test/repo',
+				branch: '-dangerous',
+				repoSubPaths: [],
+				resourcesDirectoryPath: testDir,
+				specialAgentInstructions: '',
+				quiet: true
+			};
+
+			expect(loadGitResource(args)).rejects.toThrow("must not start with '-'");
+		});
+
+		it('throws error for branch name with spaces', async () => {
+			const args: BtcaGitResourceArgs = {
+				type: 'git',
+				name: 'space-branch',
+				url: 'https://github.com/test/repo',
+				branch: 'my branch',
+				repoSubPaths: [],
+				resourcesDirectoryPath: testDir,
+				specialAgentInstructions: '',
+				quiet: true
+			};
+
+			expect(loadGitResource(args)).rejects.toThrow('Branch name must contain only');
+		});
+
 		it('throws error for path traversal attempt', async () => {
 			const args: BtcaGitResourceArgs = {
 				type: 'git',
diff --git a/apps/server/src/resources/impls/git.ts b/apps/server/src/resources/impls/git.ts
index c45d185c..3edb4273 100644
--- a/apps/server/src/resources/impls/git.ts
+++ b/apps/server/src/resources/impls/git.ts
@@ -239,7 +239,7 @@ const gitClone = async (args: {
 	if (!branchValidation.success) {
 		throw new ResourceError({
 			message: branchValidation.error,
-			hint: 'Branch names can only contain letters, numbers, hyphens, underscores, dots, and forward slashes.',
+			hint: 'Branch names can only contain letters, numbers, hyphens, underscores, dots, forward slashes, and @ symbols.',
 			cause: new Error('Branch validation failed')
 		});
 	}
diff --git a/apps/server/src/resources/schema.ts b/apps/server/src/resources/schema.ts
index 0cbe203a..c1b94fac 100644
--- a/apps/server/src/resources/schema.ts
+++ b/apps/server/src/resources/schema.ts
@@ -17,7 +17,7 @@ const RESOURCE_NAME_REGEX = /^@?[a-zA-Z0-9][a-zA-Z0-9._-]*(\/[a-zA-Z0-9][a-zA-Z0
  * Branch name: alphanumeric, forward slashes, dots, underscores, and hyphens.
  * Must not start with hyphen to prevent git option injection.
  */
-const BRANCH_NAME_REGEX = /^[a-zA-Z0-9/_.-]+$/;
+const BRANCH_NAME_REGEX = /^[a-zA-Z0-9/_.\-@]+$/;
 
 const parseUrl = (value: string) =>
 	Result.try(() => new URL(value)).match({
@@ -99,7 +99,7 @@ const BranchNameSchema = z
 	.max(LIMITS.BRANCH_NAME_MAX, `Branch name too long (max ${LIMITS.BRANCH_NAME_MAX} chars)`)
 	.regex(
 		BRANCH_NAME_REGEX,
-		'Branch name must contain only alphanumeric characters, forward slashes, dots, underscores, and hyphens'
+		'Branch name must contain only alphanumeric characters, forward slashes, dots, underscores, hyphens, and @ symbols'
 	)
 	.refine((branch) => !branch.startsWith('-'), {
 		message: "Branch name must not start with '-' to prevent git option injection"
diff --git a/apps/server/src/validation/index.ts b/apps/server/src/validation/index.ts
index 1722660d..e485dd53 100644
--- a/apps/server/src/validation/index.ts
+++ b/apps/server/src/validation/index.ts
@@ -23,7 +23,7 @@ const RESOURCE_NAME_REGEX = /^@?[a-zA-Z0-9][a-zA-Z0-9._-]*(\/[a-zA-Z0-9][a-zA-Z0
  * Branch name: alphanumeric, forward slashes, dots, underscores, and hyphens.
  * Must not start with hyphen to prevent git option injection.
  */
-const BRANCH_NAME_REGEX = /^[a-zA-Z0-9/_.-]+$/;
+const BRANCH_NAME_REGEX = /^[a-zA-Z0-9/_.\-@]+$/;
 
 /**
  * Provider/Model names: letters, numbers, dots, underscores, plus, hyphens, forward slashes, colons.
@@ -152,7 +152,7 @@ export const validateBranchName = (branch: string): ValidationResult => {
 
 	if (!BRANCH_NAME_REGEX.test(branch)) {
 		return fail(
-			`Invalid branch name: "${branch}". Must contain only alphanumeric characters, forward slashes, dots, underscores, and hyphens`
+			`Invalid branch name: "${branch}". Must contain only alphanumeric characters, forward slashes, dots, underscores, hyphens, and @ symbols`
 		);
 	}
 
diff --git a/apps/web/static/btca.schema.json b/apps/web/static/btca.schema.json
index 467babe2..d79c8349 100644
--- a/apps/web/static/btca.schema.json
+++ b/apps/web/static/btca.schema.json
@@ -87,7 +87,8 @@
 				},
 				"branch": {
 					"type": "string",
-					"description": "Git branch to use",
+					"description": "Git branch, tag, or ref to use (supports monorepo-style tags like @scope/pkg@version)",
+					"pattern": "^[a-zA-Z0-9/_\\.\\-@]+$",
 					"default": "main"
 				},
 				"searchPath": {