refactor: simplify prepare logic with mode-specific implementations

src/modes/agent/index.ts

@@ -1,4 +1,8 @@
-import type { Mode } from "../types";
+import * as core from "@actions/core";
+import { mkdir, writeFile } from "fs/promises";
+import type { Mode, ModeOptions, ModeResult } from "../types";
+import { prepareMcpConfig } from "../../mcp/install-mcp-server";
+import { exportToolEnvironmentVariables } from "../../tools/export";
 
 /**
  * Agent mode implementation.
@@ -39,4 +43,54 @@ export const agentMode: Mode = {
   shouldCreateTrackingComment() {
     return false;
   },
+
+  async prepare({ context, githubToken }: ModeOptions): Promise<ModeResult> {
+    // Agent mode is designed for automation events (workflow_dispatch, schedule)
+    // and potentially other events where we want full automation without tracking
+
+    // Create prompt directory
+    await mkdir(`${process.env.RUNNER_TEMP}/claude-prompts`, {
+      recursive: true,
+    });
+
+    // Write the prompt - either override_prompt, direct_prompt, or a minimal default
+    const promptContent =
+      context.inputs.overridePrompt ||
+      context.inputs.directPrompt ||
+      `Repository: ${context.repository.owner}/${context.repository.repo}`;
+
+    await writeFile(
+      `${process.env.RUNNER_TEMP}/claude-prompts/claude-prompt.txt`,
+      promptContent,
+    );
+
+    // Export tool environment variables
+    exportToolEnvironmentVariables(agentMode, context);
+
+    // Get MCP configuration
+    const additionalMcpConfig = process.env.MCP_CONFIG || "";
+    const mcpConfig = await prepareMcpConfig({
+      githubToken,
+      owner: context.repository.owner,
+      repo: context.repository.repo,
+      branch: "", // No specific branch for agent mode
+      baseBranch: "", // No base branch needed
+      additionalMcpConfig,
+      claudeCommentId: "",
+      allowedTools: context.inputs.allowedTools,
+      context,
+    });
+
+    core.setOutput("mcp_config", mcpConfig);
+
+    return {
+      commentId: undefined,
+      branchInfo: {
+        baseBranch: "",
+        currentBranch: "",
+        claudeBranch: undefined,
+      },
+      mcpConfig,
+    };
+  },
 };

src/modes/tag/index.ts

@@ -1,5 +1,13 @@
-import type { Mode } from "../types";
+import * as core from "@actions/core";
+import type { Mode, ModeOptions, ModeResult } from "../types";
 import { checkContainsTrigger } from "../../github/validation/trigger";
+import { checkHumanActor } from "../../github/validation/actor";
+import { createInitialComment } from "../../github/operations/comments/create-initial";
+import { setupBranch } from "../../github/operations/branch";
+import { configureGitAuth } from "../../github/operations/git-config";
+import { prepareMcpConfig } from "../../mcp/install-mcp-server";
+import { fetchGitHubData } from "../../github/data/fetcher";
+import { createPrompt } from "../../create-prompt";
 
 /**
  * Tag mode implementation.
@@ -37,4 +45,82 @@ export const tagMode: Mode = {
   shouldCreateTrackingComment() {
     return true;
   },
+
+  async prepare({
+    context,
+    octokit,
+    githubToken,
+  }: ModeOptions): Promise<ModeResult> {
+    // Tag mode handles entity-based events (issues, PRs, comments)
+
+    // Check if actor is human
+    await checkHumanActor(octokit.rest, context);
+
+    // Create initial tracking comment
+    let commentId: number | undefined;
+    let commentData:
+      | Awaited<ReturnType<typeof createInitialComment>>
+      | undefined;
+    if (this.shouldCreateTrackingComment()) {
+      commentData = await createInitialComment(octokit.rest, context);
+      commentId = commentData.id;
+    }
+
+    // Fetch GitHub data - entity events always have entityNumber and isPR
+    if (!context.entityNumber || context.isPR === undefined) {
+      throw new Error("Entity events must have entityNumber and isPR defined");
+    }
+
+    const githubData = await fetchGitHubData({
+      octokits: octokit,
+      repository: `${context.repository.owner}/${context.repository.repo}`,
+      prNumber: context.entityNumber.toString(),
+      isPR: context.isPR,
+      triggerUsername: context.actor,
+    });
+
+    // Setup branch
+    const branchInfo = await setupBranch(octokit, githubData, context);
+
+    // Configure git authentication if not using commit signing
+    if (!context.inputs.useCommitSigning) {
+      try {
+        await configureGitAuth(githubToken, context, commentData?.user || null);
+      } catch (error) {
+        console.error("Failed to configure git authentication:", error);
+        throw error;
+      }
+    }
+
+    // Create prompt file
+    const modeContext = this.prepareContext(context, {
+      commentId,
+      baseBranch: branchInfo.baseBranch,
+      claudeBranch: branchInfo.claudeBranch,
+    });
+
+    await createPrompt(tagMode, modeContext, githubData, context);
+
+    // Get MCP configuration
+    const additionalMcpConfig = process.env.MCP_CONFIG || "";
+    const mcpConfig = await prepareMcpConfig({
+      githubToken,
+      owner: context.repository.owner,
+      repo: context.repository.repo,
+      branch: branchInfo.claudeBranch || branchInfo.currentBranch,
+      baseBranch: branchInfo.baseBranch,
+      additionalMcpConfig,
+      claudeCommentId: commentId?.toString() || "",
+      allowedTools: context.inputs.allowedTools,
+      context,
+    });
+
+    core.setOutput("mcp_config", mcpConfig);
+
+    return {
+      commentId,
+      branchInfo,
+      mcpConfig,
+    };
+  },
 };

src/modes/types.ts

@@ -53,4 +53,28 @@ export type Mode = {
    * Determines if this mode should create a tracking comment
    */
   shouldCreateTrackingComment(): boolean;
+
+  /**
+   * Prepares the GitHub environment for this mode.
+   * Each mode decides how to handle different event types.
+   * @returns PrepareResult with commentId, branchInfo, and mcpConfig
+   */
+  prepare(options: ModeOptions): Promise<ModeResult>;
+};
+
+// Define types for mode prepare method to avoid circular dependencies
+export type ModeOptions = {
+  context: ParsedGitHubContext;
+  octokit: any; // We'll use any to avoid circular dependency with Octokits
+  githubToken: string;
+};
+
+export type ModeResult = {
+  commentId?: number;
+  branchInfo: {
+    baseBranch: string;
+    claudeBranch?: string;
+    currentBranch: string;
+  };
+  mcpConfig: string;
 };