diff --git a/src/__tests__/reviewTasks.test.ts b/src/__tests__/reviewTasks.test.ts
index 81745c0..573a315 100644
--- a/src/__tests__/reviewTasks.test.ts
+++ b/src/__tests__/reviewTasks.test.ts
@@ -170,9 +170,10 @@ describe('buildReviewItems', () => {
 });
 
 describe('ReviewAction type', () => {
-  it('should include try, merge, delete (no skip)', () => {
-    const actions: ReviewAction[] = ['try', 'merge', 'delete'];
-    expect(actions).toHaveLength(3);
+  it('should include instruct, try, merge, delete (no skip)', () => {
+    const actions: ReviewAction[] = ['instruct', 'try', 'merge', 'delete'];
+    expect(actions).toHaveLength(4);
+    expect(actions).toContain('instruct');
     expect(actions).toContain('try');
     expect(actions).not.toContain('skip');
   });
diff --git a/src/commands/reviewTasks.ts b/src/commands/reviewTasks.ts
index 9a80625..c3c37b9 100644
--- a/src/commands/reviewTasks.ts
+++ b/src/commands/reviewTasks.ts
@@ -14,14 +14,19 @@ import {
   buildReviewItems,
   type WorktreeReviewItem,
 } from '../task/worktree.js';
-import { selectOption, confirm } from '../prompt/index.js';
+import { selectOption, confirm, promptInput } from '../prompt/index.js';
 import { info, success, error as logError, warn } from '../utils/ui.js';
 import { createLogger } from '../utils/debug.js';
+import { executeTask } from './taskExecution.js';
+import { autoCommitWorktree } from '../task/autoCommit.js';
+import { listWorkflows } from '../config/workflowLoader.js';
+import { getCurrentWorkflow } from '../config/paths.js';
+import { DEFAULT_WORKFLOW_NAME } from '../constants.js';
 
 const log = createLogger('review-tasks');
 
 /** Actions available for a reviewed worktree */
-export type ReviewAction = 'try' | 'merge' | 'delete';
+export type ReviewAction = 'try' | 'merge' | 'delete' | 'instruct';
 
 /**
  * Check if a branch has already been merged into HEAD.
@@ -66,6 +71,7 @@ async function showDiffAndPromptAction(
   const action = await selectOption<ReviewAction>(
     `Action for ${item.info.branch}:`,
     [
+      { label: 'Instruct', value: 'instruct', description: 'Give additional instructions to modify this worktree' },
       { label: 'Try merge', value: 'try', description: 'Merge without cleanup (keep worktree & branch)' },
       { label: 'Merge & cleanup', value: 'merge', description: 'Merge (if needed) and remove worktree & branch' },
       { label: 'Delete', value: 'delete', description: 'Discard changes, remove worktree and branch' },
@@ -176,6 +182,80 @@ export function deleteWorktreeBranch(projectDir: string, item: WorktreeReviewIte
   }
 }
 
+/**
+ * Get the workflow to use for instruction.
+ * If multiple workflows available, prompt user to select.
+ */
+async function selectWorkflowForInstruction(projectDir: string): Promise<string | null> {
+  const availableWorkflows = listWorkflows();
+  const currentWorkflow = getCurrentWorkflow(projectDir);
+
+  if (availableWorkflows.length === 0) {
+    return DEFAULT_WORKFLOW_NAME;
+  }
+
+  if (availableWorkflows.length === 1 && availableWorkflows[0]) {
+    return availableWorkflows[0];
+  }
+
+  // Multiple workflows: let user select
+  const options = availableWorkflows.map((name) => ({
+    label: name === currentWorkflow ? `${name} (current)` : name,
+    value: name,
+  }));
+
+  return await selectOption('Select workflow:', options);
+}
+
+/**
+ * Instruct worktree: give additional instructions to modify the worktree.
+ * Executes a task on the worktree and auto-commits if successful.
+ */
+export async function instructWorktree(
+  projectDir: string,
+  item: WorktreeReviewItem,
+): Promise<boolean> {
+  const { branch } = item.info;
+  const worktreePath = item.info.path;
+
+  // 1. Prompt for instruction
+  const instruction = await promptInput('Enter instruction');
+  if (!instruction) {
+    info('Cancelled');
+    return false;
+  }
+
+  // 2. Select workflow
+  const selectedWorkflow = await selectWorkflowForInstruction(projectDir);
+  if (!selectedWorkflow) {
+    info('Cancelled');
+    return false;
+  }
+
+  log.info('Instructing worktree', { branch, worktreePath, workflow: selectedWorkflow });
+  info(`Running instruction on ${branch}...`);
+
+  // 3. Execute task on worktree
+  const taskSuccess = await executeTask(instruction, worktreePath, selectedWorkflow, projectDir);
+
+  // 4. Auto-commit if successful
+  if (taskSuccess) {
+    const commitResult = autoCommitWorktree(worktreePath, item.taskSlug);
+    if (commitResult.success && commitResult.commitHash) {
+      info(`Auto-committed: ${commitResult.commitHash}`);
+    } else if (!commitResult.success) {
+      warn(`Auto-commit skipped: ${commitResult.message}`);
+    }
+    success(`Instruction completed on ${branch}`);
+    log.info('Instruction completed', { branch });
+  } else {
+    logError(`Instruction failed on ${branch}`);
+    log.error('Instruction failed', { branch });
+  }
+
+  return taskSuccess;
+}
+
 /**
  * Main entry point: review worktree tasks interactively.
  */
@@ -219,6 +299,9 @@ export async function reviewTasks(cwd: string): Promise<void> {
     if (action === null) continue;
 
     switch (action) {
+      case 'instruct':
+        await instructWorktree(cwd, item);
+        break;
       case 'try':
         tryMergeWorktreeBranch(cwd, item);
         break;