Add GitHub MCP support to agent mode

- Parse --allowedTools from claude_args to detect when user wants GitHub MCPs
- Wire up github_inline_comment server in prepareMcpConfig for PR contexts
- Update agent mode to use prepareMcpConfig instead of manual config
- Add comprehensive tests for parseAllowedTools edge cases
- Fix TypeScript types to support both entity and automation contexts

src/mcp/install-mcp-server.ts

@@ -1,6 +1,7 @@
 import * as core from "@actions/core";
 import { GITHUB_API_URL, GITHUB_SERVER_URL } from "../github/api/config";
-import type { ParsedGitHubContext } from "../github/context";
+import type { GitHubContext } from "../github/context";
+import { isEntityContext } from "../github/context";
 import { Octokit } from "@octokit/rest";
 
 type PrepareConfigParams = {
@@ -12,7 +13,7 @@ type PrepareConfigParams = {
   additionalMcpConfig?: string;
   claudeCommentId?: string;
   allowedTools: string[];
-  context: ParsedGitHubContext;
+  context: GitHubContext;
 };
 
 async function checkActionsReadPermission(
@@ -67,6 +68,10 @@ export async function prepareMcpConfig(
     const hasGitHubMcpTools = allowedToolsList.some((tool) =>
       tool.startsWith("mcp__github__"),
     );
+    
+    const hasInlineCommentTools = allowedToolsList.some((tool) =>
+      tool.startsWith("mcp__github_inline_comment__"),
+    );
 
     const baseMcpConfig: { mcpServers: Record<string, unknown> } = {
       mcpServers: {},
@@ -110,11 +115,29 @@ export async function prepareMcpConfig(
         },
       };
     }
+    
+    // Include inline comment server for PRs when requested via allowed tools
+    if (isEntityContext(context) && context.isPR && (hasGitHubMcpTools || hasInlineCommentTools)) {
+      baseMcpConfig.mcpServers.github_inline_comment = {
+        command: "bun",
+        args: [
+          "run",
+          `${process.env.GITHUB_ACTION_PATH}/src/mcp/github-inline-comment-server.ts`,
+        ],
+        env: {
+          GITHUB_TOKEN: githubToken,
+          REPO_OWNER: owner,
+          REPO_NAME: repo,
+          PR_NUMBER: context.entityNumber?.toString() || "",
+          GITHUB_API_URL: GITHUB_API_URL,
+        },
+      };
+    }
 
     // CI server is included when we have a workflow token and context is a PR
     const hasWorkflowToken = !!process.env.DEFAULT_WORKFLOW_TOKEN;
 
-    if (context.isPR && hasWorkflowToken) {
+    if (isEntityContext(context) && context.isPR && hasWorkflowToken) {
       // Verify the token actually has actions:read permission
       const actuallyHasPermission = await checkActionsReadPermission(
         process.env.DEFAULT_WORKFLOW_TOKEN || "",

src/modes/agent/index.ts

@@ -2,6 +2,8 @@ import * as core from "@actions/core";
 import { mkdir, writeFile } from "fs/promises";
 import type { Mode, ModeOptions, ModeResult } from "../types";
 import type { PreparedContext } from "../../create-prompt/types";
+import { prepareMcpConfig } from "../../mcp/install-mcp-server";
+import { parseAllowedTools } from "./parse-tools";
 
 /**
  * Agent mode implementation.
@@ -39,7 +41,7 @@ export const agentMode: Mode = {
     return false;
   },
 
-  async prepare({ context, githubToken, octokit }: ModeOptions): Promise<ModeResult> {
+  async prepare({ context, githubToken }: ModeOptions): Promise<ModeResult> {
     // Create prompt directory
     await mkdir(`${process.env.RUNNER_TEMP}/claude-prompts`, {
       recursive: true,
@@ -54,43 +56,43 @@ export const agentMode: Mode = {
       promptContent,
     );
 
-    const mcpConfig: any = {
-      mcpServers: {},
-    };
-
-    // Add user-provided additional MCP config if any
-    const additionalMcpConfig = process.env.MCP_CONFIG || "";
-    if (additionalMcpConfig.trim()) {
-      try {
-        const additional = JSON.parse(additionalMcpConfig);
-        if (additional && typeof additional === "object") {
-          // Merge mcpServers if both have them
-          if (additional.mcpServers && mcpConfig.mcpServers) {
-            Object.assign(mcpConfig.mcpServers, additional.mcpServers);
-          } else {
-            Object.assign(mcpConfig, additional);
-          }
-        }
-      } catch (error) {
-        core.warning(`Failed to parse additional MCP config: ${error}`);
-      }
-    }
-
-    // Agent mode: pass through user's claude_args with MCP config
+    // Parse allowed tools from user's claude_args
     const userClaudeArgs = process.env.CLAUDE_ARGS || "";
-    const escapedMcpConfig = JSON.stringify(mcpConfig).replace(/'/g, "'\\''");
-    const claudeArgs =
-      `--mcp-config '${escapedMcpConfig}' ${userClaudeArgs}`.trim();
+    const allowedTools = parseAllowedTools(userClaudeArgs);
+    
+    // Detect current branch from GitHub environment
+    const currentBranch = process.env.GITHUB_HEAD_REF || 
+                         process.env.GITHUB_REF_NAME || 
+                         "main";
+    
+    // Get MCP configuration with GitHub servers when requested
+    const additionalMcpConfig = process.env.MCP_CONFIG || "";
+    const mcpConfig = await prepareMcpConfig({
+      githubToken,
+      owner: context.repository.owner,
+      repo: context.repository.repo,
+      branch: currentBranch,
+      baseBranch: context.inputs.baseBranch || "main",
+      additionalMcpConfig,
+      claudeCommentId: undefined, // No tracking comment in agent mode
+      allowedTools,
+      context,
+    });
+
+    // Build final claude_args
+    const escapedMcpConfig = mcpConfig.replace(/'/g, "'\\''");
+    const claudeArgs = `--mcp-config '${escapedMcpConfig}' ${userClaudeArgs}`.trim();
+    
     core.setOutput("claude_args", claudeArgs);
 
     return {
       commentId: undefined,
       branchInfo: {
-        baseBranch: "",
-        currentBranch: "",
+        baseBranch: context.inputs.baseBranch || "main",
+        currentBranch,
         claudeBranch: undefined,
       },
-      mcpConfig: JSON.stringify(mcpConfig),
+      mcpConfig,
     };
   },
 

src/modes/agent/parse-tools.ts

@@ -0,0 +1,22 @@
+export function parseAllowedTools(claudeArgs: string): string[] {
+  // Match --allowedTools followed by the value
+  // Handle both quoted and unquoted values
+  const patterns = [
+    /--allowedTools\s+"([^"]+)"/,           // Double quoted
+    /--allowedTools\s+'([^']+)'/,           // Single quoted  
+    /--allowedTools\s+([^\s]+)/,            // Unquoted
+  ];
+  
+  for (const pattern of patterns) {
+    const match = claudeArgs.match(pattern);
+    if (match && match[1]) {
+      // Don't return if the value starts with -- (another flag)
+      if (match[1].startsWith('--')) {
+        return [];
+      }
+      return match[1].split(',').map(t => t.trim());
+    }
+  }
+  
+  return [];
+}

test/modes/parse-tools.test.ts

@@ -0,0 +1,69 @@
+import { describe, test, expect } from "bun:test";
+import { parseAllowedTools } from "../../src/modes/agent/parse-tools";
+
+describe("parseAllowedTools", () => {
+  test("parses unquoted tools", () => {
+    const args = "--allowedTools mcp__github__*,mcp__github_comment__*";
+    expect(parseAllowedTools(args)).toEqual([
+      "mcp__github__*",
+      "mcp__github_comment__*",
+    ]);
+  });
+
+  test("parses double-quoted tools", () => {
+    const args = '--allowedTools "mcp__github__*,mcp__github_comment__*"';
+    expect(parseAllowedTools(args)).toEqual([
+      "mcp__github__*",
+      "mcp__github_comment__*",
+    ]);
+  });
+
+  test("parses single-quoted tools", () => {
+    const args = "--allowedTools 'mcp__github__*,mcp__github_comment__*'";
+    expect(parseAllowedTools(args)).toEqual([
+      "mcp__github__*",
+      "mcp__github_comment__*",
+    ]);
+  });
+
+  test("returns empty array when no allowedTools", () => {
+    const args = "--someOtherFlag value";
+    expect(parseAllowedTools(args)).toEqual([]);
+  });
+
+  test("handles empty string", () => {
+    expect(parseAllowedTools("")).toEqual([]);
+  });
+
+  test("handles duplicate --allowedTools flags", () => {
+    const args = "--allowedTools --allowedTools mcp__github__*";
+    // Should not match the first one since the value is another flag
+    expect(parseAllowedTools(args)).toEqual([]);
+  });
+
+  test("handles typo --alloedTools", () => {
+    const args = "--alloedTools mcp__github__*";
+    expect(parseAllowedTools(args)).toEqual([]);
+  });
+
+  test("handles multiple flags with allowedTools in middle", () => {
+    const args = '--flag1 value1 --allowedTools "mcp__github__*" --flag2 value2';
+    expect(parseAllowedTools(args)).toEqual(["mcp__github__*"]);
+  });
+
+  test("trims whitespace from tool names", () => {
+    const args = "--allowedTools 'mcp__github__* , mcp__github_comment__* '";
+    expect(parseAllowedTools(args)).toEqual([
+      "mcp__github__*",
+      "mcp__github_comment__*",
+    ]);
+  });
+
+  test("handles tools with special characters", () => {
+    const args = '--allowedTools "mcp__github__create_issue,mcp__github_comment__update"';
+    expect(parseAllowedTools(args)).toEqual([
+      "mcp__github__create_issue",
+      "mcp__github_comment__update",
+    ]);
+  });
+});