diff --git a/CLAUDE.md b/CLAUDE.md
index e05c2ee9c..6c636bdde 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -11,7 +11,7 @@ bun run format:check    # Check formatting
 
 ## What This Is
 
-A GitHub Action that lets Claude respond to `@claude` mentions on issues/PRs (tag mode) or run tasks via `prompt` input (agent mode). Mode is auto-detected: if `prompt` is provided, it's agent mode; if triggered by a comment/issue event with `@claude`, it's tag mode. See `src/modes/registry.ts`.
+A GitHub Action that lets Claude respond to `@claude` mentions on issues/PRs (tag mode) or run tasks via `prompt` input (agent mode). Mode is auto-detected: if `prompt` is provided, it's agent mode; if triggered by a comment/issue event with `@claude`, it's tag mode. See `src/modes/detector.ts`.
 
 ## How It Runs
 
@@ -23,9 +23,9 @@ Single entrypoint: `src/entrypoints/run.ts` orchestrates everything — prepare
 
 **Auth priority**: `github_token` input (user-provided) > GitHub App OIDC token (default). The `claude_code_oauth_token` and `anthropic_api_key` are for the Claude API, not GitHub. Token setup lives in `src/github/token.ts`.
 
-**Mode lifecycle**: Modes implement `shouldTrigger()` → `prepare()` → `prepareContext()` → `getSystemPrompt()`. The registry in `src/modes/registry.ts` picks the mode based on event type and inputs. To add a new mode, implement the `Mode` type from `src/modes/types.ts` and register it.
+**Mode lifecycle**: `detectMode()` in `src/modes/detector.ts` picks the mode name ("tag" or "agent"). Trigger checking and prepare dispatch are inlined in `run.ts`: tag mode calls `prepareTagMode()` from `src/modes/tag/`, agent mode calls `prepareAgentMode()` from `src/modes/agent/`.
 
-**Prompt construction**: `src/prepare/` builds the prompt by fetching GitHub data (`src/github/data/fetcher.ts`), formatting it as markdown (`src/github/data/formatter.ts`), and writing it to a temp file. The prompt includes issue/PR body, comments, diff, and CI status. This is the most important part of the action — it's what Claude sees.
+**Prompt construction**: Tag mode's `prepareTagMode()` builds the prompt by fetching GitHub data (`src/github/data/fetcher.ts`), formatting it as markdown (`src/github/data/formatter.ts`), and writing it to a temp file via `createPrompt()`. Agent mode writes the user's prompt directly. The prompt includes issue/PR body, comments, diff, and CI status. This is the most important part of the action — it's what Claude sees.
 
 ## Things That Will Bite You
 
diff --git a/src/create-prompt/index.ts b/src/create-prompt/index.ts
index 66149eac3..4624c198f 100644
--- a/src/create-prompt/index.ts
+++ b/src/create-prompt/index.ts
@@ -20,7 +20,6 @@ import {
 import type { ParsedGitHubContext } from "../github/context";
 import type { CommonFields, PreparedContext, EventData } from "./types";
 import { GITHUB_SERVER_URL } from "../github/api/config";
-import type { Mode, ModeContext } from "../modes/types";
 import { extractUserRequest } from "../utils/extract-user-request";
 export type { CommonFields, PreparedContext } from "./types";
 
@@ -458,9 +457,31 @@ export function generatePrompt(
   context: PreparedContext,
   githubData: FetchDataResult,
   useCommitSigning: boolean,
-  mode: Mode,
+  modeName: "tag" | "agent",
 ): string {
-  return mode.generatePrompt(context, githubData, useCommitSigning);
+  if (modeName === "agent") {
+    return context.prompt || `Repository: ${context.repository}`;
+  }
+
+  // Tag mode
+  const defaultPrompt = generateDefaultPrompt(
+    context,
+    githubData,
+    useCommitSigning,
+  );
+
+  if (context.githubContext?.inputs?.prompt) {
+    return (
+      defaultPrompt +
+      `
+
+<custom_instructions>
+${context.githubContext.inputs.prompt}
+</custom_instructions>`
+    );
+  }
+
+  return defaultPrompt;
 }
 
 /**
@@ -901,28 +922,20 @@ function extractUserRequestFromContext(
 }
 
 export async function createPrompt(
-  mode: Mode,
-  modeContext: ModeContext,
+  commentId: number,
+  baseBranch: string | undefined,
+  claudeBranch: string | undefined,
   githubData: FetchDataResult,
   context: ParsedGitHubContext,
 ) {
   try {
-    // Prepare the context for prompt generation
-    let claudeCommentId: string = "";
-    if (mode.name === "tag") {
-      if (!modeContext.commentId) {
-        throw new Error(
-          `${mode.name} mode requires a comment ID for prompt generation`,
-        );
-      }
-      claudeCommentId = modeContext.commentId.toString();
-    }
+    const claudeCommentId = commentId.toString();
 
     const preparedContext = prepareContext(
       context,
       claudeCommentId,
-      modeContext.baseBranch,
-      modeContext.claudeBranch,
+      baseBranch,
+      claudeBranch,
     );
 
     await mkdir(`${process.env.RUNNER_TEMP || "/tmp"}/claude-prompts`, {
@@ -934,7 +947,7 @@ export async function createPrompt(
       preparedContext,
       githubData,
       context.inputs.useCommitSigning,
-      mode,
+      "tag",
     );
 
     // Log the final prompt to console
@@ -967,19 +980,12 @@ export async function createPrompt(
     // Set allowed tools
     const hasActionsReadPermission = false;
 
-    // Get mode-specific tools
-    const modeAllowedTools = mode.getAllowedTools();
-    const modeDisallowedTools = mode.getDisallowedTools();
-
     const allAllowedTools = buildAllowedToolsString(
-      modeAllowedTools,
+      [],
       hasActionsReadPermission,
       context.inputs.useCommitSigning,
     );
-    const allDisallowedTools = buildDisallowedToolsString(
-      modeDisallowedTools,
-      modeAllowedTools,
-    );
+    const allDisallowedTools = buildDisallowedToolsString([], []);
 
     core.exportVariable("ALLOWED_TOOLS", allAllowedTools);
     core.exportVariable("DISALLOWED_TOOLS", allDisallowedTools);
diff --git a/src/entrypoints/prepare.ts b/src/entrypoints/prepare.ts
index af0ce9d26..a0b0aad6b 100644
--- a/src/entrypoints/prepare.ts
+++ b/src/entrypoints/prepare.ts
@@ -10,8 +10,10 @@ import { setupGitHubToken } from "../github/token";
 import { checkWritePermissions } from "../github/validation/permissions";
 import { createOctokit } from "../github/api/client";
 import { parseGitHubContext, isEntityContext } from "../github/context";
-import { getMode } from "../modes/registry";
-import { prepare } from "../prepare";
+import { detectMode } from "../modes/detector";
+import { prepareTagMode } from "../modes/tag";
+import { prepareAgentMode } from "../modes/agent";
+import { checkContainsTrigger } from "../github/validation/trigger";
 import { collectActionInputsPresence } from "./collect-inputs";
 
 async function run() {
@@ -22,7 +24,10 @@ async function run() {
     const context = parseGitHubContext();
 
     // Auto-detect mode based on context
-    const mode = getMode(context);
+    const modeName = detectMode(context);
+    console.log(
+      `Auto-detected mode: ${modeName} for event: ${context.eventName}`,
+    );
 
     // Setup GitHub token
     const githubToken = await setupGitHubToken();
@@ -46,10 +51,13 @@ async function run() {
     }
 
     // Check trigger conditions
-    const containsTrigger = mode.shouldTrigger(context);
+    const containsTrigger =
+      modeName === "tag"
+        ? isEntityContext(context) && checkContainsTrigger(context)
+        : !!context.inputs?.prompt;
 
     // Debug logging
-    console.log(`Mode: ${mode.name}`);
+    console.log(`Mode: ${modeName}`);
     console.log(`Context prompt: ${context.inputs?.prompt || "NO PROMPT"}`);
     console.log(`Trigger result: ${containsTrigger}`);
 
@@ -63,31 +71,20 @@ async function run() {
       return;
     }
 
-    // Step 5: Use the new modular prepare function
-    const result = await prepare({
-      context,
-      octokit,
-      mode,
-      githubToken,
-    });
+    // Run prepare
+    console.log(
+      `Preparing with mode: ${modeName} for event: ${context.eventName}`,
+    );
+    if (modeName === "tag") {
+      await prepareTagMode({ context, octokit, githubToken });
+    } else {
+      await prepareAgentMode({ context, octokit, githubToken });
+    }
 
     // MCP config is handled by individual modes (tag/agent) and included in their claude_args output
 
     // Expose the GitHub token (Claude App token) as an output
     core.setOutput("github_token", githubToken);
-
-    // Step 6: Get system prompt from mode if available
-    if (mode.getSystemPrompt) {
-      const modeContext = mode.prepareContext(context, {
-        commentId: result.commentId,
-        baseBranch: result.branchInfo.baseBranch,
-        claudeBranch: result.branchInfo.claudeBranch,
-      });
-      const systemPrompt = mode.getSystemPrompt(modeContext);
-      if (systemPrompt) {
-        core.exportVariable("APPEND_SYSTEM_PROMPT", systemPrompt);
-      }
-    }
   } catch (error) {
     const errorMessage = error instanceof Error ? error.message : String(error);
     core.setFailed(`Prepare step failed with error: ${errorMessage}`);
diff --git a/src/entrypoints/run.ts b/src/entrypoints/run.ts
index 871fa1915..54eae0139 100644
--- a/src/entrypoints/run.ts
+++ b/src/entrypoints/run.ts
@@ -17,8 +17,10 @@ import { createOctokit } from "../github/api/client";
 import type { Octokits } from "../github/api/client";
 import { parseGitHubContext, isEntityContext } from "../github/context";
 import type { GitHubContext } from "../github/context";
-import { getMode } from "../modes/registry";
-import { prepare } from "../prepare";
+import { detectMode } from "../modes/detector";
+import { prepareTagMode } from "../modes/tag";
+import { prepareAgentMode } from "../modes/agent";
+import { checkContainsTrigger } from "../github/validation/trigger";
 import { collectActionInputsPresence } from "./collect-inputs";
 import { updateCommentLink } from "./update-comment-link";
 import { formatTurnsFromData } from "./format-turns";
@@ -138,7 +140,10 @@ async function run() {
     // Phase 1: Prepare
     const actionInputsPresent = collectActionInputsPresence();
     context = parseGitHubContext();
-    const mode = getMode(context);
+    const modeName = detectMode(context);
+    console.log(
+      `Auto-detected mode: ${modeName} for event: ${context.eventName}`,
+    );
 
     try {
       githubToken = await setupGitHubToken();
@@ -173,8 +178,11 @@ async function run() {
     }
 
     // Check trigger conditions
-    const containsTrigger = mode.shouldTrigger(context);
-    console.log(`Mode: ${mode.name}`);
+    const containsTrigger =
+      modeName === "tag"
+        ? isEntityContext(context) && checkContainsTrigger(context)
+        : !!context.inputs?.prompt;
+    console.log(`Mode: ${modeName}`);
     console.log(`Context prompt: ${context.inputs?.prompt || "NO PROMPT"}`);
     console.log(`Trigger result: ${containsTrigger}`);
 
@@ -185,31 +193,19 @@ async function run() {
     }
 
     // Run prepare
-    const prepareResult = await prepare({
-      context,
-      octokit,
-      mode,
-      githubToken,
-    });
+    console.log(
+      `Preparing with mode: ${modeName} for event: ${context.eventName}`,
+    );
+    const prepareResult =
+      modeName === "tag"
+        ? await prepareTagMode({ context, octokit, githubToken })
+        : await prepareAgentMode({ context, octokit, githubToken });
 
     commentId = prepareResult.commentId;
     claudeBranch = prepareResult.branchInfo.claudeBranch;
     baseBranch = prepareResult.branchInfo.baseBranch;
     prepareCompleted = true;
 
-    // Set system prompt if available
-    if (mode.getSystemPrompt) {
-      const modeContext = mode.prepareContext(context, {
-        commentId: prepareResult.commentId,
-        baseBranch: prepareResult.branchInfo.baseBranch,
-        claudeBranch: prepareResult.branchInfo.claudeBranch,
-      });
-      const systemPrompt = mode.getSystemPrompt(modeContext);
-      if (systemPrompt) {
-        core.exportVariable("APPEND_SYSTEM_PROMPT", systemPrompt);
-      }
-    }
-
     // Phase 2: Install Claude Code CLI
     await installClaudeCode();
 
diff --git a/src/modes/agent/index.ts b/src/modes/agent/index.ts
index 0e9376c61..e6047379c 100644
--- a/src/modes/agent/index.ts
+++ b/src/modes/agent/index.ts
@@ -1,7 +1,4 @@
-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";
 import {
@@ -10,211 +7,128 @@ import {
 } from "../../github/operations/git-config";
 import { checkHumanActor } from "../../github/validation/actor";
 import type { GitHubContext } from "../../github/context";
-import { isEntityContext } from "../../github/context";
+import type { Octokits } from "../../github/api/client";
 
 /**
- * Extract GitHub context as environment variables for agent mode
- */
-function extractGitHubContext(context: GitHubContext): Record<string, string> {
-  const envVars: Record<string, string> = {};
-
-  // Basic repository info
-  envVars.GITHUB_REPOSITORY = context.repository.full_name;
-  envVars.GITHUB_TRIGGER_ACTOR = context.actor;
-  envVars.GITHUB_EVENT_NAME = context.eventName;
-
-  // Entity-specific context (PR/issue numbers, branches, etc.)
-  if (isEntityContext(context)) {
-    if (context.isPR) {
-      envVars.GITHUB_PR_NUMBER = String(context.entityNumber);
-
-      // Extract branch info from payload if available
-      if (
-        context.payload &&
-        "pull_request" in context.payload &&
-        context.payload.pull_request
-      ) {
-        envVars.GITHUB_BASE_REF = context.payload.pull_request.base?.ref || "";
-        envVars.GITHUB_HEAD_REF = context.payload.pull_request.head?.ref || "";
-      }
-    } else {
-      envVars.GITHUB_ISSUE_NUMBER = String(context.entityNumber);
-    }
-  }
-
-  return envVars;
-}
-
-/**
- * Agent mode implementation.
+ * Prepares the agent mode execution context.
  *
- * This mode runs whenever an explicit prompt is provided in the workflow configuration.
+ * Agent mode runs whenever an explicit prompt is provided in the workflow configuration.
  * It bypasses the standard @claude mention checking and comment tracking used by tag mode,
  * providing direct access to Claude Code for automation workflows.
  */
-export const agentMode: Mode = {
-  name: "agent",
-  description: "Direct automation mode for explicit prompts",
-
-  shouldTrigger(context) {
-    // Only trigger when an explicit prompt is provided
-    return !!context.inputs?.prompt;
-  },
-
-  prepareContext(context) {
-    // Agent mode doesn't use comment tracking or branch management
-    return {
-      mode: "agent",
-      githubContext: context,
+export async function prepareAgentMode({
+  context,
+  octokit,
+  githubToken,
+}: {
+  context: GitHubContext;
+  octokit: Octokits;
+  githubToken: string;
+}) {
+  // Check if actor is human (prevents bot-triggered loops)
+  await checkHumanActor(octokit.rest, context);
+
+  // Configure git authentication for agent mode (same as tag mode)
+  // SSH signing takes precedence if provided
+  const useSshSigning = !!context.inputs.sshSigningKey;
+  const useApiCommitSigning = context.inputs.useCommitSigning && !useSshSigning;
+
+  if (useSshSigning) {
+    // Setup SSH signing for commits
+    await setupSshSigning(context.inputs.sshSigningKey);
+
+    // Still configure git auth for push operations (user/email and remote URL)
+    const user = {
+      login: context.inputs.botName,
+      id: parseInt(context.inputs.botId),
     };
-  },
-
-  getAllowedTools() {
-    return [];
-  },
-
-  getDisallowedTools() {
-    return [];
-  },
-
-  shouldCreateTrackingComment() {
-    return false;
-  },
-
-  async prepare({
-    context,
-    octokit,
-    githubToken,
-  }: ModeOptions): Promise<ModeResult> {
-    // Check if actor is human (prevents bot-triggered loops)
-    await checkHumanActor(octokit.rest, context);
-
-    // Configure git authentication for agent mode (same as tag mode)
-    // SSH signing takes precedence if provided
-    const useSshSigning = !!context.inputs.sshSigningKey;
-    const useApiCommitSigning =
-      context.inputs.useCommitSigning && !useSshSigning;
-
-    if (useSshSigning) {
-      // Setup SSH signing for commits
-      await setupSshSigning(context.inputs.sshSigningKey);
-
-      // Still configure git auth for push operations (user/email and remote URL)
-      const user = {
-        login: context.inputs.botName,
-        id: parseInt(context.inputs.botId),
-      };
-      try {
-        await configureGitAuth(githubToken, context, user);
-      } catch (error) {
-        console.error("Failed to configure git authentication:", error);
-        // Continue anyway - git operations may still work with default config
-      }
-    } else if (!useApiCommitSigning) {
-      // Use bot_id and bot_name from inputs directly
-      const user = {
-        login: context.inputs.botName,
-        id: parseInt(context.inputs.botId),
-      };
-
-      try {
-        // Use the shared git configuration function
-        await configureGitAuth(githubToken, context, user);
-      } catch (error) {
-        console.error("Failed to configure git authentication:", error);
-        // Continue anyway - git operations may still work with default config
-      }
+    try {
+      await configureGitAuth(githubToken, context, user);
+    } catch (error) {
+      console.error("Failed to configure git authentication:", error);
+      // Continue anyway - git operations may still work with default config
     }
+  } else if (!useApiCommitSigning) {
+    // Use bot_id and bot_name from inputs directly
+    const user = {
+      login: context.inputs.botName,
+      id: parseInt(context.inputs.botId),
+    };
 
-    // Create prompt directory
-    await mkdir(`${process.env.RUNNER_TEMP || "/tmp"}/claude-prompts`, {
-      recursive: true,
-    });
-
-    // Write the prompt file - use the user's prompt directly
-    const promptContent =
-      context.inputs.prompt ||
-      `Repository: ${context.repository.owner}/${context.repository.repo}`;
-
-    await writeFile(
-      `${process.env.RUNNER_TEMP || "/tmp"}/claude-prompts/claude-prompt.txt`,
-      promptContent,
-    );
-
-    // Parse allowed tools from user's claude_args
-    const userClaudeArgs = process.env.CLAUDE_ARGS || "";
-    const allowedTools = parseAllowedTools(userClaudeArgs);
-
-    // Check for branch info from environment variables (useful for auto-fix workflows)
-    const claudeBranch = process.env.CLAUDE_BRANCH || undefined;
-    const baseBranch =
-      process.env.BASE_BRANCH || context.inputs.baseBranch || "main";
-
-    // Detect current branch from GitHub environment
-    const currentBranch =
-      claudeBranch ||
-      process.env.GITHUB_HEAD_REF ||
-      process.env.GITHUB_REF_NAME ||
-      "main";
-
-    // Get our GitHub MCP servers config
-    const ourMcpConfig = await prepareMcpConfig({
-      githubToken,
-      owner: context.repository.owner,
-      repo: context.repository.repo,
-      branch: currentBranch,
-      baseBranch: baseBranch,
-      claudeCommentId: undefined, // No tracking comment in agent mode
-      allowedTools,
-      mode: "agent",
-      context,
-    });
-
-    // Build final claude_args with multiple --mcp-config flags
-    let claudeArgs = "";
-
-    // Add our GitHub servers config if we have any
-    const ourConfig = JSON.parse(ourMcpConfig);
-    if (ourConfig.mcpServers && Object.keys(ourConfig.mcpServers).length > 0) {
-      const escapedOurConfig = ourMcpConfig.replace(/'/g, "'\\''");
-      claudeArgs = `--mcp-config '${escapedOurConfig}'`;
+    try {
+      // Use the shared git configuration function
+      await configureGitAuth(githubToken, context, user);
+    } catch (error) {
+      console.error("Failed to configure git authentication:", error);
+      // Continue anyway - git operations may still work with default config
     }
+  }
 
-    // Append user's claude_args (which may have more --mcp-config flags)
-    claudeArgs = `${claudeArgs} ${userClaudeArgs}`.trim();
-
-    return {
-      commentId: undefined,
-      branchInfo: {
-        baseBranch: baseBranch,
-        currentBranch: baseBranch, // Use base branch as current when creating new branch
-        claudeBranch: claudeBranch,
-      },
-      mcpConfig: ourMcpConfig,
-      claudeArgs,
-    };
-  },
-
-  generatePrompt(context: PreparedContext): string {
-    // Inject GitHub context as environment variables
-    if (context.githubContext) {
-      const envVars = extractGitHubContext(context.githubContext);
-      for (const [key, value] of Object.entries(envVars)) {
-        core.exportVariable(key, value);
-      }
-    }
+  // Create prompt directory
+  await mkdir(`${process.env.RUNNER_TEMP || "/tmp"}/claude-prompts`, {
+    recursive: true,
+  });
+
+  // Write the prompt file - use the user's prompt directly
+  const promptContent =
+    context.inputs.prompt ||
+    `Repository: ${context.repository.owner}/${context.repository.repo}`;
+
+  await writeFile(
+    `${process.env.RUNNER_TEMP || "/tmp"}/claude-prompts/claude-prompt.txt`,
+    promptContent,
+  );
+
+  // Parse allowed tools from user's claude_args
+  const userClaudeArgs = process.env.CLAUDE_ARGS || "";
+  const allowedTools = parseAllowedTools(userClaudeArgs);
+
+  // Check for branch info from environment variables (useful for auto-fix workflows)
+  const claudeBranch = process.env.CLAUDE_BRANCH || undefined;
+  const baseBranch =
+    process.env.BASE_BRANCH || context.inputs.baseBranch || "main";
+
+  // Detect current branch from GitHub environment
+  const currentBranch =
+    claudeBranch ||
+    process.env.GITHUB_HEAD_REF ||
+    process.env.GITHUB_REF_NAME ||
+    "main";
+
+  // Get our GitHub MCP servers config
+  const ourMcpConfig = await prepareMcpConfig({
+    githubToken,
+    owner: context.repository.owner,
+    repo: context.repository.repo,
+    branch: currentBranch,
+    baseBranch: baseBranch,
+    claudeCommentId: undefined, // No tracking comment in agent mode
+    allowedTools,
+    mode: "agent",
+    context,
+  });
 
-    // Agent mode uses prompt field
-    if (context.prompt) {
-      return context.prompt;
-    }
+  // Build final claude_args with multiple --mcp-config flags
+  let claudeArgs = "";
+
+  // Add our GitHub servers config if we have any
+  const ourConfig = JSON.parse(ourMcpConfig);
+  if (ourConfig.mcpServers && Object.keys(ourConfig.mcpServers).length > 0) {
+    const escapedOurConfig = ourMcpConfig.replace(/'/g, "'\\''");
+    claudeArgs = `--mcp-config '${escapedOurConfig}'`;
+  }
 
-    // Minimal fallback - repository is a string in PreparedContext
-    return `Repository: ${context.repository}`;
-  },
+  // Append user's claude_args (which may have more --mcp-config flags)
+  claudeArgs = `${claudeArgs} ${userClaudeArgs}`.trim();
 
-  getSystemPrompt() {
-    // Agent mode doesn't need additional system prompts
-    return undefined;
-  },
-};
+  return {
+    commentId: undefined,
+    branchInfo: {
+      baseBranch: baseBranch,
+      currentBranch: baseBranch, // Use base branch as current when creating new branch
+      claudeBranch: claudeBranch,
+    },
+    mcpConfig: ourMcpConfig,
+    claudeArgs,
+  };
+}
diff --git a/src/modes/detector.ts b/src/modes/detector.ts
index 8e30aff4f..c15ce88a1 100644
--- a/src/modes/detector.ts
+++ b/src/modes/detector.ts
@@ -80,17 +80,6 @@ export function detectMode(context: GitHubContext): AutoDetectedMode {
   return "agent";
 }
 
-export function getModeDescription(mode: AutoDetectedMode): string {
-  switch (mode) {
-    case "tag":
-      return "Interactive mode triggered by @claude mentions";
-    case "agent":
-      return "Direct automation mode for explicit prompts";
-    default:
-      return "Unknown mode";
-  }
-}
-
 function validateTrackProgressEvent(context: GitHubContext): void {
   // track_progress is only valid for pull_request and issue events
   const validEvents = [
@@ -123,21 +112,3 @@ function validateTrackProgressEvent(context: GitHubContext): void {
     }
   }
 }
-
-export function shouldUseTrackingComment(mode: AutoDetectedMode): boolean {
-  return mode === "tag";
-}
-
-export function getDefaultPromptForMode(
-  mode: AutoDetectedMode,
-  context: GitHubContext,
-): string | undefined {
-  switch (mode) {
-    case "tag":
-      return undefined;
-    case "agent":
-      return context.inputs?.prompt;
-    default:
-      return undefined;
-  }
-}
diff --git a/src/modes/registry.ts b/src/modes/registry.ts
deleted file mode 100644
index 9df69980c..000000000
--- a/src/modes/registry.ts
+++ /dev/null
@@ -1,54 +0,0 @@
-/**
- * Mode Registry for claude-code-action v1.0
- *
- * This module provides access to all available execution modes and handles
- * automatic mode detection based on GitHub event types.
- */
-
-import type { Mode, ModeName } from "./types";
-import { tagMode } from "./tag";
-import { agentMode } from "./agent";
-import type { GitHubContext } from "../github/context";
-import { detectMode, type AutoDetectedMode } from "./detector";
-
-export const VALID_MODES = ["tag", "agent"] as const;
-
-/**
- * All available modes in v1.0
- */
-const modes = {
-  tag: tagMode,
-  agent: agentMode,
-} as const satisfies Record<AutoDetectedMode, Mode>;
-
-/**
- * Automatically detects and retrieves the appropriate mode based on the GitHub context.
- * In v1.0, modes are auto-selected based on event type.
- * @param context The GitHub context
- * @returns The appropriate mode for the context
- */
-export function getMode(context: GitHubContext): Mode {
-  const modeName = detectMode(context);
-  console.log(
-    `Auto-detected mode: ${modeName} for event: ${context.eventName}`,
-  );
-
-  const mode = modes[modeName];
-  if (!mode) {
-    throw new Error(
-      `Mode '${modeName}' not found. This should not happen. Please report this issue.`,
-    );
-  }
-
-  return mode;
-}
-
-/**
- * Type guard to check if a string is a valid mode name.
- * @param name The string to check
- * @returns True if the name is a valid mode name
- */
-export function isValidMode(name: string): name is ModeName {
-  const validModes = ["tag", "agent"];
-  return validModes.includes(name);
-}
diff --git a/src/modes/tag/index.ts b/src/modes/tag/index.ts
index 89f688810..0adf746c2 100644
--- a/src/modes/tag/index.ts
+++ b/src/modes/tag/index.ts
@@ -1,5 +1,3 @@
-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";
@@ -14,241 +12,177 @@ import {
   extractOriginalTitle,
   extractOriginalBody,
 } from "../../github/data/fetcher";
-import { createPrompt, generateDefaultPrompt } from "../../create-prompt";
+import { createPrompt } from "../../create-prompt";
 import { isEntityContext } from "../../github/context";
-import type { PreparedContext } from "../../create-prompt/types";
-import type { FetchDataResult } from "../../github/data/fetcher";
+import type { GitHubContext } from "../../github/context";
+import type { Octokits } from "../../github/api/client";
 import { parseAllowedTools } from "../agent/parse-tools";
 
 /**
- * Tag mode implementation.
+ * Prepares the tag mode execution context.
  *
- * The traditional implementation mode that responds to @claude mentions,
- * issue assignments, or labels. Creates tracking comments showing progress
- * and has full implementation capabilities.
+ * Tag mode responds to @claude mentions, issue assignments, or labels.
+ * Creates tracking comments showing progress and has full implementation capabilities.
  */
-export const tagMode: Mode = {
-  name: "tag",
-  description: "Traditional implementation mode triggered by @claude mentions",
-
-  shouldTrigger(context) {
-    // Tag mode only handles entity events
-    if (!isEntityContext(context)) {
-      return false;
-    }
-    return checkContainsTrigger(context);
-  },
-
-  prepareContext(context, data) {
-    return {
-      mode: "tag",
-      githubContext: context,
-      commentId: data?.commentId,
-      baseBranch: data?.baseBranch,
-      claudeBranch: data?.claudeBranch,
+export async function prepareTagMode({
+  context,
+  octokit,
+  githubToken,
+}: {
+  context: GitHubContext;
+  octokit: Octokits;
+  githubToken: string;
+}) {
+  // Tag mode only handles entity-based events
+  if (!isEntityContext(context)) {
+    throw new Error("Tag mode requires entity context");
+  }
+
+  // Check if actor is human
+  await checkHumanActor(octokit.rest, context);
+
+  // Create initial tracking comment
+  const commentData = await createInitialComment(octokit.rest, context);
+  const commentId = commentData.id;
+
+  const triggerTime = extractTriggerTimestamp(context);
+  const originalTitle = extractOriginalTitle(context);
+  const originalBody = extractOriginalBody(context);
+
+  const githubData = await fetchGitHubData({
+    octokits: octokit,
+    repository: `${context.repository.owner}/${context.repository.repo}`,
+    prNumber: context.entityNumber.toString(),
+    isPR: context.isPR,
+    triggerUsername: context.actor,
+    triggerTime,
+    originalTitle,
+    originalBody,
+    includeCommentsByActor: context.inputs.includeCommentsByActor,
+    excludeCommentsByActor: context.inputs.excludeCommentsByActor,
+  });
+
+  // Setup branch
+  const branchInfo = await setupBranch(octokit, githubData, context);
+
+  // Configure git authentication
+  // SSH signing takes precedence if provided
+  const useSshSigning = !!context.inputs.sshSigningKey;
+  const useApiCommitSigning = context.inputs.useCommitSigning && !useSshSigning;
+
+  if (useSshSigning) {
+    // Setup SSH signing for commits
+    await setupSshSigning(context.inputs.sshSigningKey);
+
+    // Still configure git auth for push operations (user/email and remote URL)
+    const user = {
+      login: context.inputs.botName,
+      id: parseInt(context.inputs.botId),
     };
-  },
-
-  getAllowedTools() {
-    return [];
-  },
-
-  getDisallowedTools() {
-    return [];
-  },
-
-  shouldCreateTrackingComment() {
-    return true;
-  },
-
-  async prepare({
-    context,
-    octokit,
-    githubToken,
-  }: ModeOptions): Promise<ModeResult> {
-    // Tag mode only handles entity-based events
-    if (!isEntityContext(context)) {
-      throw new Error("Tag mode requires entity context");
+    try {
+      await configureGitAuth(githubToken, context, user);
+    } catch (error) {
+      console.error("Failed to configure git authentication:", error);
+      throw error;
     }
+  } else if (!useApiCommitSigning) {
+    // Use bot_id and bot_name from inputs directly
+    const user = {
+      login: context.inputs.botName,
+      id: parseInt(context.inputs.botId),
+    };
 
-    // Check if actor is human
-    await checkHumanActor(octokit.rest, context);
-
-    // Create initial tracking comment
-    const commentData = await createInitialComment(octokit.rest, context);
-    const commentId = commentData.id;
-
-    const triggerTime = extractTriggerTimestamp(context);
-    const originalTitle = extractOriginalTitle(context);
-    const originalBody = extractOriginalBody(context);
-
-    const githubData = await fetchGitHubData({
-      octokits: octokit,
-      repository: `${context.repository.owner}/${context.repository.repo}`,
-      prNumber: context.entityNumber.toString(),
-      isPR: context.isPR,
-      triggerUsername: context.actor,
-      triggerTime,
-      originalTitle,
-      originalBody,
-      includeCommentsByActor: context.inputs.includeCommentsByActor,
-      excludeCommentsByActor: context.inputs.excludeCommentsByActor,
-    });
-
-    // Setup branch
-    const branchInfo = await setupBranch(octokit, githubData, context);
-
-    // Configure git authentication
-    // SSH signing takes precedence if provided
-    const useSshSigning = !!context.inputs.sshSigningKey;
-    const useApiCommitSigning =
-      context.inputs.useCommitSigning && !useSshSigning;
-
-    if (useSshSigning) {
-      // Setup SSH signing for commits
-      await setupSshSigning(context.inputs.sshSigningKey);
-
-      // Still configure git auth for push operations (user/email and remote URL)
-      const user = {
-        login: context.inputs.botName,
-        id: parseInt(context.inputs.botId),
-      };
-      try {
-        await configureGitAuth(githubToken, context, user);
-      } catch (error) {
-        console.error("Failed to configure git authentication:", error);
-        throw error;
-      }
-    } else if (!useApiCommitSigning) {
-      // Use bot_id and bot_name from inputs directly
-      const user = {
-        login: context.inputs.botName,
-        id: parseInt(context.inputs.botId),
-      };
-
-      try {
-        await configureGitAuth(githubToken, context, user);
-      } catch (error) {
-        console.error("Failed to configure git authentication:", error);
-        throw error;
-      }
+    try {
+      await configureGitAuth(githubToken, context, user);
+    } 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);
-
-    const userClaudeArgs = process.env.CLAUDE_ARGS || "";
-    const userAllowedMCPTools = parseAllowedTools(userClaudeArgs).filter(
-      (tool) => tool.startsWith("mcp__github_"),
+  }
+
+  // Create prompt file
+  await createPrompt(
+    commentId,
+    branchInfo.baseBranch,
+    branchInfo.claudeBranch,
+    githubData,
+    context,
+  );
+
+  const userClaudeArgs = process.env.CLAUDE_ARGS || "";
+  const userAllowedMCPTools = parseAllowedTools(userClaudeArgs).filter((tool) =>
+    tool.startsWith("mcp__github_"),
+  );
+
+  // Build claude_args for tag mode with required tools
+  // Tag mode REQUIRES these tools to function properly
+  const tagModeTools = [
+    "Edit",
+    "MultiEdit",
+    "Glob",
+    "Grep",
+    "LS",
+    "Read",
+    "Write",
+    "mcp__github_comment__update_claude_comment",
+    "mcp__github_ci__get_ci_status",
+    "mcp__github_ci__get_workflow_run_details",
+    "mcp__github_ci__download_job_log",
+    ...userAllowedMCPTools,
+  ];
+
+  // Add git commands when using git CLI (no API commit signing, or SSH signing)
+  // SSH signing still uses git CLI, just with signing enabled
+  if (!useApiCommitSigning) {
+    tagModeTools.push(
+      "Bash(git add:*)",
+      "Bash(git commit:*)",
+      "Bash(git push:*)",
+      "Bash(git status:*)",
+      "Bash(git diff:*)",
+      "Bash(git log:*)",
+      "Bash(git rm:*)",
     );
-
-    // Build claude_args for tag mode with required tools
-    // Tag mode REQUIRES these tools to function properly
-    const tagModeTools = [
-      "Edit",
-      "MultiEdit",
-      "Glob",
-      "Grep",
-      "LS",
-      "Read",
-      "Write",
-      "mcp__github_comment__update_claude_comment",
-      "mcp__github_ci__get_ci_status",
-      "mcp__github_ci__get_workflow_run_details",
-      "mcp__github_ci__download_job_log",
-      ...userAllowedMCPTools,
-    ];
-
-    // Add git commands when using git CLI (no API commit signing, or SSH signing)
-    // SSH signing still uses git CLI, just with signing enabled
-    if (!useApiCommitSigning) {
-      tagModeTools.push(
-        "Bash(git add:*)",
-        "Bash(git commit:*)",
-        "Bash(git push:*)",
-        "Bash(git status:*)",
-        "Bash(git diff:*)",
-        "Bash(git log:*)",
-        "Bash(git rm:*)",
-      );
-    } else {
-      // When using API commit signing, use MCP file ops tools
-      tagModeTools.push(
-        "mcp__github_file_ops__commit_files",
-        "mcp__github_file_ops__delete_files",
-      );
-    }
-
-    // Get our GitHub MCP servers configuration
-    const ourMcpConfig = await prepareMcpConfig({
-      githubToken,
-      owner: context.repository.owner,
-      repo: context.repository.repo,
-      branch: branchInfo.claudeBranch || branchInfo.currentBranch,
-      baseBranch: branchInfo.baseBranch,
-      claudeCommentId: commentId.toString(),
-      allowedTools: Array.from(new Set(tagModeTools)),
-      mode: "tag",
-      context,
-    });
-
-    // Build complete claude_args with multiple --mcp-config flags
-    let claudeArgs = "";
-
-    // Add our GitHub servers config
-    const escapedOurConfig = ourMcpConfig.replace(/'/g, "'\\''");
-    claudeArgs = `--mcp-config '${escapedOurConfig}'`;
-
-    // Add required tools for tag mode
-    claudeArgs += ` --allowedTools "${tagModeTools.join(",")}"`;
-
-    // Append user's claude_args (which may have more --mcp-config flags)
-    if (userClaudeArgs) {
-      claudeArgs += ` ${userClaudeArgs}`;
-    }
-
-    return {
-      commentId,
-      branchInfo,
-      mcpConfig: ourMcpConfig,
-      claudeArgs: claudeArgs.trim(),
-    };
-  },
-
-  generatePrompt(
-    context: PreparedContext,
-    githubData: FetchDataResult,
-    useCommitSigning: boolean,
-  ): string {
-    const defaultPrompt = generateDefaultPrompt(
-      context,
-      githubData,
-      useCommitSigning,
+  } else {
+    // When using API commit signing, use MCP file ops tools
+    tagModeTools.push(
+      "mcp__github_file_ops__commit_files",
+      "mcp__github_file_ops__delete_files",
     );
+  }
 
-    // If a custom prompt is provided, inject it into the tag mode prompt
-    if (context.githubContext?.inputs?.prompt) {
-      return (
-        defaultPrompt +
-        `
-
-<custom_instructions>
-${context.githubContext.inputs.prompt}
-</custom_instructions>`
-      );
-    }
-
-    return defaultPrompt;
-  },
-
-  getSystemPrompt() {
-    // Tag mode doesn't need additional system prompts
-    return undefined;
-  },
-};
+  // Get our GitHub MCP servers configuration
+  const ourMcpConfig = await prepareMcpConfig({
+    githubToken,
+    owner: context.repository.owner,
+    repo: context.repository.repo,
+    branch: branchInfo.claudeBranch || branchInfo.currentBranch,
+    baseBranch: branchInfo.baseBranch,
+    claudeCommentId: commentId.toString(),
+    allowedTools: Array.from(new Set(tagModeTools)),
+    mode: "tag",
+    context,
+  });
+
+  // Build complete claude_args with multiple --mcp-config flags
+  let claudeArgs = "";
+
+  // Add our GitHub servers config
+  const escapedOurConfig = ourMcpConfig.replace(/'/g, "'\\''");
+  claudeArgs = `--mcp-config '${escapedOurConfig}'`;
+
+  // Add required tools for tag mode
+  claudeArgs += ` --allowedTools "${tagModeTools.join(",")}"`;
+
+  // Append user's claude_args (which may have more --mcp-config flags)
+  if (userClaudeArgs) {
+    claudeArgs += ` ${userClaudeArgs}`;
+  }
+
+  return {
+    commentId,
+    branchInfo,
+    mcpConfig: ourMcpConfig,
+    claudeArgs: claudeArgs.trim(),
+  };
+}
diff --git a/src/modes/types.ts b/src/modes/types.ts
deleted file mode 100644
index 3d653ccd3..000000000
--- a/src/modes/types.ts
+++ /dev/null
@@ -1,101 +0,0 @@
-import type { GitHubContext } from "../github/context";
-import type { PreparedContext } from "../create-prompt/types";
-import type { FetchDataResult } from "../github/data/fetcher";
-import type { Octokits } from "../github/api/client";
-
-export type ModeName = "tag" | "agent";
-
-export type ModeContext = {
-  mode: ModeName;
-  githubContext: GitHubContext;
-  commentId?: number;
-  baseBranch?: string;
-  claudeBranch?: string;
-};
-
-export type ModeData = {
-  commentId?: number;
-  baseBranch?: string;
-  claudeBranch?: string;
-};
-
-/**
- * Mode interface for claude-code-action execution modes.
- * Each mode defines its own behavior for trigger detection, prompt generation,
- * and tracking comment creation.
- *
- * Current modes include:
- * - 'tag': Interactive mode triggered by @claude mentions
- * - 'agent': Direct automation mode triggered by explicit prompts
- */
-export type Mode = {
-  name: ModeName;
-  description: string;
-
-  /**
-   * Determines if this mode should trigger based on the GitHub context
-   */
-  shouldTrigger(context: GitHubContext): boolean;
-
-  /**
-   * Prepares the mode context with any additional data needed for prompt generation
-   */
-  prepareContext(context: GitHubContext, data?: ModeData): ModeContext;
-
-  /**
-   * Returns the list of tools that should be allowed for this mode
-   */
-  getAllowedTools(): string[];
-
-  /**
-   * Returns the list of tools that should be disallowed for this mode
-   */
-  getDisallowedTools(): string[];
-
-  /**
-   * Determines if this mode should create a tracking comment
-   */
-  shouldCreateTrackingComment(): boolean;
-
-  /**
-   * Generates the prompt for this mode.
-   * @returns The complete prompt string
-   */
-  generatePrompt(
-    context: PreparedContext,
-    githubData: FetchDataResult,
-    useCommitSigning: boolean,
-  ): string;
-
-  /**
-   * 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>;
-
-  /**
-   * Returns an optional system prompt to append to Claude's base system prompt.
-   * This allows modes to add mode-specific instructions.
-   * @returns The system prompt string or undefined if no additional prompt is needed
-   */
-  getSystemPrompt?(context: ModeContext): string | undefined;
-};
-
-// Define types for mode prepare method
-export type ModeOptions = {
-  context: GitHubContext;
-  octokit: Octokits;
-  githubToken: string;
-};
-
-export type ModeResult = {
-  commentId?: number;
-  branchInfo: {
-    baseBranch: string;
-    claudeBranch?: string;
-    currentBranch: string;
-  };
-  mcpConfig: string;
-  claudeArgs: string;
-};
diff --git a/src/prepare/index.ts b/src/prepare/index.ts
deleted file mode 100644
index 6f4230192..000000000
--- a/src/prepare/index.ts
+++ /dev/null
@@ -1,20 +0,0 @@
-/**
- * Main prepare module that delegates to the mode's prepare method
- */
-
-import type { PrepareOptions, PrepareResult } from "./types";
-
-export async function prepare(options: PrepareOptions): Promise<PrepareResult> {
-  const { mode, context, octokit, githubToken } = options;
-
-  console.log(
-    `Preparing with mode: ${mode.name} for event: ${context.eventName}`,
-  );
-
-  // Delegate to the mode's prepare method
-  return mode.prepare({
-    context,
-    octokit,
-    githubToken,
-  });
-}
diff --git a/src/prepare/types.ts b/src/prepare/types.ts
deleted file mode 100644
index 72ece515b..000000000
--- a/src/prepare/types.ts
+++ /dev/null
@@ -1,21 +0,0 @@
-import type { GitHubContext } from "../github/context";
-import type { Octokits } from "../github/api/client";
-import type { Mode } from "../modes/types";
-
-export type PrepareResult = {
-  commentId?: number;
-  branchInfo: {
-    baseBranch: string;
-    claudeBranch?: string;
-    currentBranch: string;
-  };
-  mcpConfig: string;
-  claudeArgs: string;
-};
-
-export type PrepareOptions = {
-  context: GitHubContext;
-  octokit: Octokits;
-  mode: Mode;
-  githubToken: string;
-};
diff --git a/test/create-prompt.test.ts b/test/create-prompt.test.ts
index ca2468175..0a5ea8253 100644
--- a/test/create-prompt.test.ts
+++ b/test/create-prompt.test.ts
@@ -3,60 +3,13 @@
 import { describe, test, expect } from "bun:test";
 import {
   generatePrompt,
-  generateDefaultPrompt,
   getEventTypeAndContext,
   buildAllowedToolsString,
   buildDisallowedToolsString,
 } from "../src/create-prompt";
 import type { PreparedContext } from "../src/create-prompt";
-import type { Mode } from "../src/modes/types";
 
 describe("generatePrompt", () => {
-  // Create a mock tag mode that uses the default prompt
-  const mockTagMode: Mode = {
-    name: "tag",
-    description: "Tag mode",
-    shouldTrigger: () => true,
-    prepareContext: (context) => ({ mode: "tag", githubContext: context }),
-    getAllowedTools: () => [],
-    getDisallowedTools: () => [],
-    shouldCreateTrackingComment: () => true,
-    generatePrompt: (context, githubData, useCommitSigning) =>
-      generateDefaultPrompt(context, githubData, useCommitSigning),
-    prepare: async () => ({
-      commentId: 123,
-      branchInfo: {
-        baseBranch: "main",
-        currentBranch: "main",
-        claudeBranch: undefined,
-      },
-      mcpConfig: "{}",
-      claudeArgs: "",
-    }),
-  };
-
-  // Create a mock agent mode that passes through prompts
-  const mockAgentMode: Mode = {
-    name: "agent",
-    description: "Agent mode",
-    shouldTrigger: () => true,
-    prepareContext: (context) => ({ mode: "agent", githubContext: context }),
-    getAllowedTools: () => [],
-    getDisallowedTools: () => [],
-    shouldCreateTrackingComment: () => false,
-    generatePrompt: (context) => context.prompt || "",
-    prepare: async () => ({
-      commentId: undefined,
-      branchInfo: {
-        baseBranch: "main",
-        currentBranch: "main",
-        claudeBranch: undefined,
-      },
-      mcpConfig: "{}",
-      claudeArgs: "",
-    }),
-  };
-
   const mockGitHubData = {
     contextData: {
       title: "Test PR",
@@ -181,12 +134,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     expect(prompt).toContain("You are Claude, an AI assistant");
     expect(prompt).toContain("<event_type>GENERAL_COMMENT</event_type>");
@@ -214,12 +162,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     expect(prompt).toContain("<event_type>PR_REVIEW</event_type>");
     expect(prompt).toContain("<is_pr>true</is_pr>");
@@ -245,12 +188,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     expect(prompt).toContain("<event_type>ISSUE_CREATED</event_type>");
     expect(prompt).toContain(
@@ -278,12 +216,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     expect(prompt).toContain("<event_type>ISSUE_ASSIGNED</event_type>");
     expect(prompt).toContain(
@@ -310,12 +243,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     expect(prompt).toContain("<event_type>ISSUE_LABELED</event_type>");
     expect(prompt).toContain(
@@ -341,12 +269,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     expect(prompt).toContain("<event_type>PULL_REQUEST</event_type>");
     expect(prompt).toContain("<is_pr>true</is_pr>");
@@ -370,12 +293,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     // Verify prompt generates successfully without custom instructions
     expect(prompt).toContain("@claude please fix this");
@@ -400,7 +318,7 @@ describe("generatePrompt", () => {
       envVars,
       mockGitHubData,
       false,
-      mockAgentMode,
+      "agent",
     );
 
     // Agent mode: Prompt is passed through as-is
@@ -441,7 +359,7 @@ describe("generatePrompt", () => {
       envVars,
       mockGitHubData,
       false,
-      mockAgentMode,
+      "agent",
     );
 
     // v1.0: Variables are NOT substituted - prompt is passed as-is to Claude Code
@@ -490,7 +408,7 @@ describe("generatePrompt", () => {
       envVars,
       issueGitHubData,
       false,
-      mockAgentMode,
+      "agent",
     );
 
     // Agent mode: Prompt is passed through as-is
@@ -515,7 +433,7 @@ describe("generatePrompt", () => {
       envVars,
       mockGitHubData,
       false,
-      mockAgentMode,
+      "agent",
     );
 
     // Agent mode: No substitution - passed as-is
@@ -539,12 +457,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     expect(prompt).toContain("You are Claude, an AI assistant");
     expect(prompt).toContain("<event_type>ISSUE_CREATED</event_type>");
@@ -567,12 +480,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     expect(prompt).toContain("<trigger_username>johndoe</trigger_username>");
     // With commit signing disabled, co-author info appears in git commit instructions
@@ -594,12 +502,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     // Should contain PR-specific instructions (git commands when not using signing)
     expect(prompt).toContain("git push");
@@ -630,12 +533,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     // Should contain Issue-specific instructions
     expect(prompt).toContain(
@@ -674,12 +572,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     // Should contain the actual branch name with timestamp
     expect(prompt).toContain(
@@ -709,12 +602,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     // Should contain branch-specific instructions like issues
     expect(prompt).toContain(
@@ -752,12 +640,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     // Should contain open PR instructions (git commands when not using signing)
     expect(prompt).toContain("git push");
@@ -788,12 +671,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     // Should contain new branch instructions
     expect(prompt).toContain(
@@ -821,12 +699,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     // Should contain new branch instructions
     expect(prompt).toContain(
@@ -854,12 +727,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     // Should contain new branch instructions
     expect(prompt).toContain(
@@ -883,12 +751,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      false,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, false, "tag");
 
     // Should have git command instructions
     expect(prompt).toContain("Use git commands via the Bash tool");
@@ -917,12 +780,7 @@ describe("generatePrompt", () => {
       },
     };
 
-    const prompt = await generatePrompt(
-      envVars,
-      mockGitHubData,
-      true,
-      mockTagMode,
-    );
+    const prompt = await generatePrompt(envVars, mockGitHubData, true, "tag");
 
     // Should have commit signing tool instructions
     expect(prompt).toContain("mcp__github_file_ops__commit_files");
diff --git a/test/modes/agent.test.ts b/test/modes/agent.test.ts
index b7224069b..be6f0d2b1 100644
--- a/test/modes/agent.test.ts
+++ b/test/modes/agent.test.ts
@@ -7,22 +7,17 @@ import {
   spyOn,
   mock,
 } from "bun:test";
-import { agentMode } from "../../src/modes/agent";
-import type { GitHubContext } from "../../src/github/context";
-import { createMockContext, createMockAutomationContext } from "../mockContext";
+import { prepareAgentMode } from "../../src/modes/agent";
+import { createMockAutomationContext } from "../mockContext";
 import * as core from "@actions/core";
 import * as gitConfig from "../../src/github/operations/git-config";
 
 describe("Agent Mode", () => {
-  let mockContext: GitHubContext;
   let exportVariableSpy: any;
   let setOutputSpy: any;
   let configureGitAuthSpy: any;
 
   beforeEach(() => {
-    mockContext = createMockAutomationContext({
-      eventName: "workflow_dispatch",
-    });
     exportVariableSpy = spyOn(core, "exportVariable").mockImplementation(
       () => {},
     );
@@ -45,84 +40,11 @@ describe("Agent Mode", () => {
     configureGitAuthSpy?.mockRestore();
   });
 
-  test("agent mode has correct properties", () => {
-    expect(agentMode.name).toBe("agent");
-    expect(agentMode.description).toBe(
-      "Direct automation mode for explicit prompts",
-    );
-    expect(agentMode.shouldCreateTrackingComment()).toBe(false);
-    expect(agentMode.getAllowedTools()).toEqual([]);
-    expect(agentMode.getDisallowedTools()).toEqual([]);
-  });
-
-  test("prepareContext returns minimal data", () => {
-    const context = agentMode.prepareContext(mockContext);
-
-    expect(context.mode).toBe("agent");
-    expect(context.githubContext).toBe(mockContext);
-    // Agent mode doesn't use comment tracking or branch management
-    expect(Object.keys(context)).toEqual(["mode", "githubContext"]);
-  });
-
-  test("agent mode only triggers when prompt is provided", () => {
-    // Should NOT trigger for automation events without prompt
-    const workflowDispatchContext = createMockAutomationContext({
-      eventName: "workflow_dispatch",
-    });
-    expect(agentMode.shouldTrigger(workflowDispatchContext)).toBe(false);
-
-    const scheduleContext = createMockAutomationContext({
-      eventName: "schedule",
-    });
-    expect(agentMode.shouldTrigger(scheduleContext)).toBe(false);
-
-    const repositoryDispatchContext = createMockAutomationContext({
-      eventName: "repository_dispatch",
-    });
-    expect(agentMode.shouldTrigger(repositoryDispatchContext)).toBe(false);
-
-    // Should NOT trigger for entity events without prompt
-    const entityEvents = [
-      "issue_comment",
-      "pull_request",
-      "pull_request_review",
-      "issues",
-    ] as const;
-
-    entityEvents.forEach((eventName) => {
-      const contextNoPrompt = createMockContext({ eventName });
-      expect(agentMode.shouldTrigger(contextNoPrompt)).toBe(false);
-    });
-
-    // Should trigger for ANY event when prompt is provided
-    const allEvents = [
-      "workflow_dispatch",
-      "repository_dispatch",
-      "schedule",
-      "issue_comment",
-      "pull_request",
-      "pull_request_review",
-      "issues",
-    ] as const;
-
-    allEvents.forEach((eventName) => {
-      const contextWithPrompt =
-        eventName === "workflow_dispatch" ||
-        eventName === "repository_dispatch" ||
-        eventName === "schedule"
-          ? createMockAutomationContext({
-              eventName,
-              inputs: { prompt: "Do something" },
-            })
-          : createMockContext({
-              eventName,
-              inputs: { prompt: "Do something" },
-            });
-      expect(agentMode.shouldTrigger(contextWithPrompt)).toBe(true);
-    });
+  test("prepareAgentMode is exported as a function", () => {
+    expect(typeof prepareAgentMode).toBe("function");
   });
 
-  test("prepare method passes through claude_args", async () => {
+  test("prepare passes through claude_args", async () => {
     // Clear any previous calls before this test
     exportVariableSpy.mockClear();
     setOutputSpy.mockClear();
@@ -156,7 +78,7 @@ describe("Agent Mode", () => {
         },
       },
     } as any;
-    const result = await agentMode.prepare({
+    const result = await prepareAgentMode({
       context: contextWithCustomArgs,
       octokit: mockOctokit,
       githubToken: "test-token",
@@ -186,7 +108,7 @@ describe("Agent Mode", () => {
       process.env.GITHUB_REF_NAME = originalRefName;
   });
 
-  test("prepare method rejects bot actors without allowed_bots", async () => {
+  test("prepare rejects bot actors without allowed_bots", async () => {
     const contextWithPrompts = createMockAutomationContext({
       eventName: "workflow_dispatch",
     });
@@ -206,7 +128,7 @@ describe("Agent Mode", () => {
     } as any;
 
     await expect(
-      agentMode.prepare({
+      prepareAgentMode({
         context: contextWithPrompts,
         octokit: mockOctokit,
         githubToken: "test-token",
@@ -216,7 +138,7 @@ describe("Agent Mode", () => {
     );
   });
 
-  test("prepare method allows bot actors when in allowed_bots list", async () => {
+  test("prepare allows bot actors when in allowed_bots list", async () => {
     const contextWithPrompts = createMockAutomationContext({
       eventName: "workflow_dispatch",
     });
@@ -237,7 +159,7 @@ describe("Agent Mode", () => {
 
     // Should not throw - bot is in allowed list
     await expect(
-      agentMode.prepare({
+      prepareAgentMode({
         context: contextWithPrompts,
         octokit: mockOctokit,
         githubToken: "test-token",
@@ -245,7 +167,7 @@ describe("Agent Mode", () => {
     ).resolves.toBeDefined();
   });
 
-  test("prepare method creates prompt file with correct content", async () => {
+  test("prepare creates prompt file with correct content", async () => {
     const contextWithPrompts = createMockAutomationContext({
       eventName: "workflow_dispatch",
     });
@@ -268,7 +190,7 @@ describe("Agent Mode", () => {
         },
       },
     } as any;
-    const result = await agentMode.prepare({
+    const result = await prepareAgentMode({
       context: contextWithPrompts,
       octokit: mockOctokit,
       githubToken: "test-token",
diff --git a/test/modes/registry.test.ts b/test/modes/registry.test.ts
deleted file mode 100644
index 7c585b27f..000000000
--- a/test/modes/registry.test.ts
+++ /dev/null
@@ -1,155 +0,0 @@
-import { describe, test, expect } from "bun:test";
-import { getMode, isValidMode } from "../../src/modes/registry";
-import { agentMode } from "../../src/modes/agent";
-import { tagMode } from "../../src/modes/tag";
-import {
-  createMockContext,
-  createMockAutomationContext,
-  mockRepositoryDispatchContext,
-} from "../mockContext";
-
-describe("Mode Registry", () => {
-  const mockContext = createMockContext({
-    eventName: "issue_comment",
-    payload: {
-      action: "created",
-      comment: {
-        body: "Test comment without trigger",
-      },
-    } as any,
-  });
-
-  const mockWorkflowDispatchContext = createMockAutomationContext({
-    eventName: "workflow_dispatch",
-  });
-
-  const mockScheduleContext = createMockAutomationContext({
-    eventName: "schedule",
-  });
-
-  test("getMode auto-detects agent mode for issue_comment without trigger", () => {
-    const mode = getMode(mockContext);
-    // Agent mode is the default when no trigger is found
-    expect(mode).toBe(agentMode);
-    expect(mode.name).toBe("agent");
-  });
-
-  test("getMode auto-detects agent mode for workflow_dispatch", () => {
-    const mode = getMode(mockWorkflowDispatchContext);
-    expect(mode).toBe(agentMode);
-    expect(mode.name).toBe("agent");
-  });
-
-  // Removed test - explicit mode override no longer supported in v1.0
-
-  test("getMode auto-detects agent for workflow_dispatch", () => {
-    const mode = getMode(mockWorkflowDispatchContext);
-    expect(mode).toBe(agentMode);
-    expect(mode.name).toBe("agent");
-  });
-
-  test("getMode auto-detects agent for schedule event", () => {
-    const mode = getMode(mockScheduleContext);
-    expect(mode).toBe(agentMode);
-    expect(mode.name).toBe("agent");
-  });
-
-  test("getMode auto-detects agent for repository_dispatch event", () => {
-    const mode = getMode(mockRepositoryDispatchContext);
-    expect(mode).toBe(agentMode);
-    expect(mode.name).toBe("agent");
-  });
-
-  test("getMode auto-detects agent for repository_dispatch with client_payload", () => {
-    const contextWithPayload = createMockAutomationContext({
-      eventName: "repository_dispatch",
-      payload: {
-        action: "trigger-analysis",
-        client_payload: {
-          source: "external-system",
-          metadata: { priority: "high" },
-        },
-        repository: {
-          name: "test-repo",
-          owner: { login: "test-owner" },
-        },
-        sender: { login: "automation-user" },
-      },
-    });
-
-    const mode = getMode(contextWithPayload);
-    expect(mode).toBe(agentMode);
-    expect(mode.name).toBe("agent");
-  });
-
-  // Removed test - legacy mode names no longer supported in v1.0
-
-  test("getMode auto-detects agent mode for PR opened", () => {
-    const prContext = createMockContext({
-      eventName: "pull_request",
-      payload: { action: "opened" } as any,
-      isPR: true,
-    });
-    const mode = getMode(prContext);
-    expect(mode).toBe(agentMode);
-    expect(mode.name).toBe("agent");
-  });
-
-  test("getMode uses agent mode when prompt is provided, even with @claude mention", () => {
-    const contextWithPrompt = createMockContext({
-      eventName: "issue_comment",
-      payload: {
-        action: "created",
-        comment: {
-          body: "@claude please help",
-        },
-      } as any,
-      inputs: {
-        prompt: "/review",
-      } as any,
-    });
-    const mode = getMode(contextWithPrompt);
-    expect(mode).toBe(agentMode);
-    expect(mode.name).toBe("agent");
-  });
-
-  test("getMode uses tag mode for @claude mention without prompt", () => {
-    // Ensure PROMPT env var is not set (clean up from previous tests)
-    const originalPrompt = process.env.PROMPT;
-    delete process.env.PROMPT;
-
-    const contextWithMention = createMockContext({
-      eventName: "issue_comment",
-      payload: {
-        action: "created",
-        comment: {
-          body: "@claude please help",
-        },
-      } as any,
-      inputs: {
-        triggerPhrase: "@claude",
-        prompt: "",
-      } as any,
-    });
-    const mode = getMode(contextWithMention);
-    expect(mode).toBe(tagMode);
-    expect(mode.name).toBe("tag");
-
-    // Restore original value if it existed
-    if (originalPrompt !== undefined) {
-      process.env.PROMPT = originalPrompt;
-    }
-  });
-
-  // Removed test - explicit mode override no longer supported in v1.0
-
-  test("isValidMode returns true for all valid modes", () => {
-    expect(isValidMode("tag")).toBe(true);
-    expect(isValidMode("agent")).toBe(true);
-  });
-
-  test("isValidMode returns false for invalid mode", () => {
-    expect(isValidMode("invalid")).toBe(false);
-    expect(isValidMode("review")).toBe(false);
-  });
-});
diff --git a/test/modes/tag.test.ts b/test/modes/tag.test.ts
index d592463f5..d68d7fc20 100644
--- a/test/modes/tag.test.ts
+++ b/test/modes/tag.test.ts
@@ -1,92 +1,8 @@
-import { describe, test, expect, beforeEach } from "bun:test";
-import { tagMode } from "../../src/modes/tag";
-import type { ParsedGitHubContext } from "../../src/github/context";
-import type { IssueCommentEvent } from "@octokit/webhooks-types";
-import { createMockContext } from "../mockContext";
+import { describe, test, expect } from "bun:test";
+import { prepareTagMode } from "../../src/modes/tag";
 
 describe("Tag Mode", () => {
-  let mockContext: ParsedGitHubContext;
-
-  beforeEach(() => {
-    mockContext = createMockContext({
-      eventName: "issue_comment",
-      isPR: false,
-    });
-  });
-
-  test("tag mode has correct properties", () => {
-    expect(tagMode.name).toBe("tag");
-    expect(tagMode.description).toBe(
-      "Traditional implementation mode triggered by @claude mentions",
-    );
-    expect(tagMode.shouldCreateTrackingComment()).toBe(true);
-  });
-
-  test("shouldTrigger delegates to checkContainsTrigger", () => {
-    const contextWithTrigger = createMockContext({
-      eventName: "issue_comment",
-      isPR: false,
-      inputs: {
-        ...createMockContext().inputs,
-        triggerPhrase: "@claude",
-      },
-      payload: {
-        comment: {
-          body: "Hey @claude, can you help?",
-        },
-      } as IssueCommentEvent,
-    });
-
-    expect(tagMode.shouldTrigger(contextWithTrigger)).toBe(true);
-
-    const contextWithoutTrigger = createMockContext({
-      eventName: "issue_comment",
-      isPR: false,
-      inputs: {
-        ...createMockContext().inputs,
-        triggerPhrase: "@claude",
-      },
-      payload: {
-        comment: {
-          body: "This is just a regular comment",
-        },
-      } as IssueCommentEvent,
-    });
-
-    expect(tagMode.shouldTrigger(contextWithoutTrigger)).toBe(false);
-  });
-
-  test("prepareContext includes all required data", () => {
-    const data = {
-      commentId: 123,
-      baseBranch: "main",
-      claudeBranch: "claude/fix-bug",
-    };
-
-    const context = tagMode.prepareContext(mockContext, data);
-
-    expect(context.mode).toBe("tag");
-    expect(context.githubContext).toBe(mockContext);
-    expect(context.commentId).toBe(123);
-    expect(context.baseBranch).toBe("main");
-    expect(context.claudeBranch).toBe("claude/fix-bug");
-  });
-
-  test("prepareContext works without data", () => {
-    const context = tagMode.prepareContext(mockContext);
-
-    expect(context.mode).toBe("tag");
-    expect(context.githubContext).toBe(mockContext);
-    expect(context.commentId).toBeUndefined();
-    expect(context.baseBranch).toBeUndefined();
-    expect(context.claudeBranch).toBeUndefined();
-  });
-
-  test("getAllowedTools returns empty array", () => {
-    expect(tagMode.getAllowedTools()).toEqual([]);
-  });
-
-  test("getDisallowedTools returns empty array", () => {
-    expect(tagMode.getDisallowedTools()).toEqual([]);
+  test("prepareTagMode is exported as a function", () => {
+    expect(typeof prepareTagMode).toBe("function");
   });
 });
diff --git a/test/pull-request-target.test.ts b/test/pull-request-target.test.ts
index 7f4fd342d..59c747f28 100644
--- a/test/pull-request-target.test.ts
+++ b/test/pull-request-target.test.ts
@@ -1,38 +1,10 @@
 #!/usr/bin/env bun
 
 import { describe, test, expect } from "bun:test";
-import {
-  getEventTypeAndContext,
-  generatePrompt,
-  generateDefaultPrompt,
-} from "../src/create-prompt";
+import { getEventTypeAndContext, generatePrompt } from "../src/create-prompt";
 import type { PreparedContext } from "../src/create-prompt";
-import type { Mode } from "../src/modes/types";
 
 describe("pull_request_target event support", () => {
-  // Mock tag mode for testing
-  const mockTagMode: Mode = {
-    name: "tag",
-    description: "Tag mode",
-    shouldTrigger: () => true,
-    prepareContext: (context) => ({ mode: "tag", githubContext: context }),
-    getAllowedTools: () => [],
-    getDisallowedTools: () => [],
-    shouldCreateTrackingComment: () => true,
-    generatePrompt: (context, githubData, useCommitSigning) =>
-      generateDefaultPrompt(context, githubData, useCommitSigning),
-    prepare: async () => ({
-      commentId: 123,
-      branchInfo: {
-        baseBranch: "main",
-        currentBranch: "main",
-        claudeBranch: undefined,
-      },
-      mcpConfig: "{}",
-      claudeArgs: "",
-    }),
-  };
-
   const mockGitHubData = {
     contextData: {
       title: "External PR via pull_request_target",
@@ -126,12 +98,7 @@ describe("pull_request_target event support", () => {
         },
       };
 
-      const prompt = generatePrompt(
-        envVars,
-        mockGitHubData,
-        false,
-        mockTagMode,
-      );
+      const prompt = generatePrompt(envVars, mockGitHubData, false, "tag");
 
       // Should contain pull request event type and metadata
       expect(prompt).toContain("<event_type>PULL_REQUEST</event_type>");
@@ -165,12 +132,7 @@ describe("pull_request_target event support", () => {
         },
       };
 
-      const prompt = generatePrompt(
-        envVars,
-        mockGitHubData,
-        false,
-        mockTagMode,
-      );
+      const prompt = generatePrompt(envVars, mockGitHubData, false, "tag");
 
       // Should include git commands for non-commit-signing mode
       expect(prompt).toContain("git push");
@@ -196,7 +158,7 @@ describe("pull_request_target event support", () => {
         },
       };
 
-      const prompt = generatePrompt(envVars, mockGitHubData, true, mockTagMode);
+      const prompt = generatePrompt(envVars, mockGitHubData, true, "tag");
 
       // Should include commit signing tools
       expect(prompt).toContain("mcp__github_file_ops__commit_files");
@@ -246,13 +208,13 @@ describe("pull_request_target event support", () => {
         pullRequestContext,
         mockGitHubData,
         false,
-        mockTagMode,
+        "tag",
       );
       const pullRequestTargetPrompt = generatePrompt(
         pullRequestTargetContext,
         mockGitHubData,
         false,
-        mockTagMode,
+        "tag",
       );
 
       // Both should have the same event type and structure
@@ -293,37 +255,7 @@ describe("pull_request_target event support", () => {
         },
       };
 
-      // Use agent mode which passes through the prompt as-is
-      const mockAgentMode: Mode = {
-        name: "agent",
-        description: "Agent mode",
-        shouldTrigger: () => true,
-        prepareContext: (context) => ({
-          mode: "agent",
-          githubContext: context,
-        }),
-        getAllowedTools: () => [],
-        getDisallowedTools: () => [],
-        shouldCreateTrackingComment: () => true,
-        generatePrompt: (context) => context.prompt || "default prompt",
-        prepare: async () => ({
-          commentId: 123,
-          branchInfo: {
-            baseBranch: "main",
-            currentBranch: "main",
-            claudeBranch: undefined,
-          },
-          mcpConfig: "{}",
-          claudeArgs: "",
-        }),
-      };
-
-      const prompt = generatePrompt(
-        envVars,
-        mockGitHubData,
-        false,
-        mockAgentMode,
-      );
+      const prompt = generatePrompt(envVars, mockGitHubData, false, "agent");
 
       expect(prompt).toBe(
         "Review this pull_request_target PR for security issues",
@@ -343,12 +275,7 @@ describe("pull_request_target event support", () => {
         },
       };
 
-      const prompt = generatePrompt(
-        envVars,
-        mockGitHubData,
-        false,
-        mockTagMode,
-      );
+      const prompt = generatePrompt(envVars, mockGitHubData, false, "tag");
 
       // Should generate default prompt structure
       expect(prompt).toContain("<event_type>PULL_REQUEST</event_type>");
@@ -418,7 +345,7 @@ describe("pull_request_target event support", () => {
 
       // Should not throw when generating prompt
       expect(() => {
-        generatePrompt(minimalContext, mockGitHubData, false, mockTagMode);
+        generatePrompt(minimalContext, mockGitHubData, false, "tag");
       }).not.toThrow();
     });
 
@@ -476,13 +403,13 @@ describe("pull_request_target event support", () => {
         internalPR,
         mockGitHubData,
         false,
-        mockTagMode,
+        "tag",
       );
       const externalPrompt = generatePrompt(
         externalPR,
         mockGitHubData,
         false,
-        mockTagMode,
+        "tag",
       );
 
       // Should have same tool access patterns