diff --git a/src/__fixtures__/agent-helpers.ts b/src/__fixtures__/agent-helpers.ts
new file mode 100644
index 00000000..bc4415d1
--- /dev/null
+++ b/src/__fixtures__/agent-helpers.ts
@@ -0,0 +1,37 @@
+/**
+ * Test fixtures and helpers for Agent testing.
+ * This module provides utilities for testing Agent-related implementations.
+ */
+
+import type { Agent } from '../agent/agent.js'
+import type { Message } from '../types/messages.js'
+import { AgentState } from '../agent/state.js'
+import type { JSONValue } from '../types/json.js'
+
+/**
+ * Data for creating a mock Agent.
+ */
+export interface MockAgentData {
+  /**
+   * Messages for the agent.
+   */
+  messages?: Message[]
+  /**
+   * Initial state for the agent.
+   */
+  state?: Record<string, JSONValue>
+}
+
+/**
+ * Helper to create a mock Agent for testing.
+ * Provides minimal Agent interface with messages and state.
+ *
+ * @param data - Optional mock agent data
+ * @returns Mock Agent object
+ */
+export function createMockAgent(data?: MockAgentData): Agent {
+  return {
+    messages: data?.messages ?? [],
+    state: new AgentState(data?.state ?? {}),
+  } as unknown as Agent
+}
diff --git a/src/__fixtures__/tool-helpers.ts b/src/__fixtures__/tool-helpers.ts
index 0fd903f0..085c1e5a 100644
--- a/src/__fixtures__/tool-helpers.ts
+++ b/src/__fixtures__/tool-helpers.ts
@@ -23,6 +23,7 @@ export function createMockContext(
     toolUse,
     agent: {
       state: new AgentState(agentState),
+      messages: [],
     },
   }
 }
diff --git a/src/agent/__tests__/agent.hook.test.ts b/src/agent/__tests__/agent.hook.test.ts
index 52a5f154..eb77a825 100644
--- a/src/agent/__tests__/agent.hook.test.ts
+++ b/src/agent/__tests__/agent.hook.test.ts
@@ -9,6 +9,7 @@ import {
   BeforeToolCallEvent,
   MessageAddedEvent,
   ModelStreamEventHook,
+  type HookRegistry,
 } from '../../hooks/index.js'
 import { MockMessageModel } from '../../__fixtures__/mock-message-model.js'
 import { MockHookProvider } from '../../__fixtures__/mock-hook-provider.js'
@@ -301,4 +302,37 @@ describe('Agent Hooks Integration', () => {
       )
     })
   })
+
+  describe('AfterModelCallEvent retryModelCall', () => {
+    it('retries model call when hook sets retryModelCall', async () => {
+      let callCount = 0
+      const retryHook = {
+        registerCallbacks: (registry: HookRegistry) => {
+          registry.addCallback(AfterModelCallEvent, (event: AfterModelCallEvent) => {
+            callCount++
+            if (callCount === 1 && event.error) {
+              event.retryModelCall = true
+            }
+          })
+        },
+      }
+
+      const model = new MockMessageModel()
+        .addTurn(new Error('First attempt failed'))
+        .addTurn({ type: 'textBlock', text: 'Success after retry' })
+
+      const agent = new Agent({ model, hooks: [retryHook] })
+      const result = await agent.invoke('Test')
+
+      expect(result.lastMessage.content[0]).toEqual({ type: 'textBlock', text: 'Success after retry' })
+      expect(callCount).toBe(2)
+    })
+
+    it('does not retry when retryModelCall is not set', async () => {
+      const model = new MockMessageModel().addTurn(new Error('Failure'))
+      const agent = new Agent({ model })
+
+      await expect(agent.invoke('Test')).rejects.toThrow('Failure')
+    })
+  })
 })
diff --git a/src/agent/agent.ts b/src/agent/agent.ts
index 1af6e055..5a7b4252 100644
--- a/src/agent/agent.ts
+++ b/src/agent/agent.ts
@@ -12,16 +12,15 @@ import {
   ToolResultBlock,
   type ToolUseBlock,
 } from '../index.js'
-import { normalizeError, ConcurrentInvocationError, MaxTokensError, ContextWindowOverflowError } from '../errors.js'
+import { normalizeError, ConcurrentInvocationError, MaxTokensError } from '../errors.js'
 import type { BaseModelConfig, Model, StreamOptions } from '../models/model.js'
 import { ToolRegistry } from '../registry/tool-registry.js'
 import { AgentState } from './state.js'
 import type { AgentData } from '../types/agent.js'
 import { AgentPrinter, getDefaultAppender, type Printer } from './printer.js'
-import type { ConversationManager } from '../conversation-manager/conversation-manager.js'
+import type { HookProvider } from '../hooks/types.js'
 import { SlidingWindowConversationManager } from '../conversation-manager/sliding-window-conversation-manager.js'
 import { HookRegistryImplementation } from '../hooks/registry.js'
-import type { HookProvider } from '../hooks/types.js'
 import {
   AfterInvocationEvent,
   AfterModelCallEvent,
@@ -74,7 +73,7 @@ export type AgentConfig = {
    * Conversation manager for handling message history and context overflow.
    * Defaults to SlidingWindowConversationManager with windowSize of 40.
    */
-  conversationManager?: ConversationManager
+  conversationManager?: HookProvider
   /**
    * Hook providers to register with the agent.
    * Hooks enable observing and extending agent behavior.
@@ -107,7 +106,7 @@ export class Agent implements AgentData {
   /**
    * Conversation manager for handling message history and context overflow.
    */
-  public readonly conversationManager: ConversationManager
+  public readonly conversationManager: HookProvider
 
   private _isInvoking: boolean = false
   private _printer?: Printer
@@ -140,10 +139,12 @@ export class Agent implements AgentData {
 
     this.state = new AgentState(config?.state)
 
+    // Initialize conversation manager
     this.conversationManager = config?.conversationManager ?? new SlidingWindowConversationManager({ windowSize: 40 })
 
-    // Initialize hooks
+    // Initialize hooks and register conversation manager hooks
     this.hooks = new HookRegistryImplementation()
+    this.hooks.addHook(this.conversationManager)
     this.hooks.addAllHooks(config?.hooks ?? [])
 
     // Create printer if printer is enabled (default: true)
@@ -283,8 +284,6 @@ export class Agent implements AgentData {
         // Continue loop
       }
     } finally {
-      this.conversationManager.applyManagement(this)
-
       // Invoke AfterInvocationEvent hook
       await this.hooks.invokeCallbacks(new AfterInvocationEvent({ agent: this }))
 
@@ -362,14 +361,14 @@ export class Agent implements AgentData {
       const modelError = normalizeError(error)
 
       // Invoke AfterModelCallEvent hook even on error
-      await this.hooks.invokeCallbacks(new AfterModelCallEvent({ agent: this, error: modelError }))
+      const event = await this.hooks.invokeCallbacks(new AfterModelCallEvent({ agent: this, error: modelError }))
 
-      if (error instanceof ContextWindowOverflowError) {
-        // Reduce context and retry
-        this.conversationManager.reduceContext(this, error)
+      // Check if hooks request a retry (e.g., after reducing context)
+      if (event.retryModelCall) {
         return yield* this.invokeModel(args)
       }
-      // Re-throw other errors
+
+      // Re-throw error
       throw error
     }
   }
diff --git a/src/conversation-manager/__tests__/conversation-manager.test.ts b/src/conversation-manager/__tests__/conversation-manager.test.ts
deleted file mode 100644
index a43d904e..00000000
--- a/src/conversation-manager/__tests__/conversation-manager.test.ts
+++ /dev/null
@@ -1,11 +0,0 @@
-import { describe, it, expect } from 'vitest'
-import { ConversationManager } from '../conversation-manager.js'
-
-describe('ConversationManager', () => {
-  // ConversationManager is an abstract base class
-  // Specific implementations are tested in their own test files
-
-  it('is an abstract class', () => {
-    expect(ConversationManager).toBeDefined()
-  })
-})
diff --git a/src/conversation-manager/__tests__/null-conversation-manager.test.ts b/src/conversation-manager/__tests__/null-conversation-manager.test.ts
index 6681c599..a79a1ce6 100644
--- a/src/conversation-manager/__tests__/null-conversation-manager.test.ts
+++ b/src/conversation-manager/__tests__/null-conversation-manager.test.ts
@@ -1,53 +1,42 @@
 import { describe, it, expect } from 'vitest'
 import { NullConversationManager } from '../null-conversation-manager.js'
-import { ContextWindowOverflowError, Message, TextBlock } from '../../index.js'
-import type { Agent } from '../../agent/agent.js'
+import { Message, TextBlock } from '../../index.js'
+import { HookRegistryImplementation } from '../../hooks/registry.js'
+import { AfterInvocationEvent, AfterModelCallEvent } from '../../hooks/events.js'
+import { ContextWindowOverflowError } from '../../errors.js'
+import { createMockAgent } from '../../__fixtures__/agent-helpers.js'
 
 describe('NullConversationManager', () => {
-  describe('applyManagement', () => {
-    it('does not modify messages array', () => {
+  describe('behavior', () => {
+    it('does not modify conversation history', async () => {
       const manager = new NullConversationManager()
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Hello')] }),
         new Message({ role: 'assistant', content: [new TextBlock('Hi there')] }),
       ]
-      const mockAgent = { messages } as unknown as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.applyManagement(mockAgent)
+      const registry = new HookRegistryImplementation()
+      manager.registerCallbacks(registry)
+
+      await registry.invokeCallbacks(new AfterInvocationEvent({ agent: mockAgent }))
 
       expect(mockAgent.messages).toHaveLength(2)
       expect(mockAgent.messages[0]!.content[0]).toEqual({ type: 'textBlock', text: 'Hello' })
       expect(mockAgent.messages[1]!.content[0]).toEqual({ type: 'textBlock', text: 'Hi there' })
     })
-  })
-
-  describe('reduceContext', () => {
-    it('re-throws provided error', () => {
-      const manager = new NullConversationManager()
-      const mockAgent = { messages: [] } as unknown as Agent
-      const testError = new Error('Test error')
-
-      expect(() => {
-        manager.reduceContext(mockAgent, testError)
-      }).toThrow(testError)
-    })
 
-    it('throws ContextWindowOverflowError when no error provided', () => {
+    it('does not set retryModelCall on context overflow', async () => {
       const manager = new NullConversationManager()
-      const mockAgent = { messages: [] } as unknown as Agent
+      const mockAgent = createMockAgent()
+      const error = new ContextWindowOverflowError('Context overflow')
 
-      expect(() => {
-        manager.reduceContext(mockAgent)
-      }).toThrow(ContextWindowOverflowError)
-    })
+      const registry = new HookRegistryImplementation()
+      manager.registerCallbacks(registry)
 
-    it('throws ContextWindowOverflowError with correct message when no error provided', () => {
-      const manager = new NullConversationManager()
-      const mockAgent = { messages: [] } as unknown as Agent
+      const event = await registry.invokeCallbacks(new AfterModelCallEvent({ agent: mockAgent, error }))
 
-      expect(() => {
-        manager.reduceContext(mockAgent)
-      }).toThrow('Context window overflowed!')
+      expect(event.retryModelCall).toBeUndefined()
     })
   })
 })
diff --git a/src/conversation-manager/__tests__/sliding-window-conversation-manager.test.ts b/src/conversation-manager/__tests__/sliding-window-conversation-manager.test.ts
index 5ab0baae..ee4a2e9f 100644
--- a/src/conversation-manager/__tests__/sliding-window-conversation-manager.test.ts
+++ b/src/conversation-manager/__tests__/sliding-window-conversation-manager.test.ts
@@ -1,8 +1,29 @@
 import { describe, it, expect } from 'vitest'
 import { SlidingWindowConversationManager } from '../sliding-window-conversation-manager.js'
 import { ContextWindowOverflowError, Message, TextBlock, ToolUseBlock, ToolResultBlock } from '../../index.js'
+import { HookRegistryImplementation } from '../../hooks/registry.js'
+import { AfterInvocationEvent, AfterModelCallEvent } from '../../hooks/events.js'
+import { createMockAgent } from '../../__fixtures__/agent-helpers.js'
 import type { Agent } from '../../agent/agent.js'
 
+// Helper to trigger sliding window management through hooks
+async function triggerSlidingWindow(manager: SlidingWindowConversationManager, agent: Agent): Promise<void> {
+  const registry = new HookRegistryImplementation()
+  registry.addHook(manager)
+  await registry.invokeCallbacks(new AfterInvocationEvent({ agent }))
+}
+
+// Helper to trigger context overflow handling through hooks
+async function triggerContextOverflow(
+  manager: SlidingWindowConversationManager,
+  agent: Agent,
+  error: Error
+): Promise<{ retryModelCall?: boolean }> {
+  const registry = new HookRegistryImplementation()
+  registry.addHook(manager)
+  return await registry.invokeCallbacks(new AfterModelCallEvent({ agent, error }))
+}
+
 describe('SlidingWindowConversationManager', () => {
   describe('constructor', () => {
     it('sets default windowSize to 40', () => {
@@ -28,42 +49,42 @@ describe('SlidingWindowConversationManager', () => {
   })
 
   describe('applyManagement', () => {
-    it('skips reduction when message count is less than window size', () => {
+    it('skips reduction when message count is less than window size', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 10 })
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Message 1')] }),
         new Message({ role: 'assistant', content: [new TextBlock('Response 1')] }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.applyManagement(mockAgent)
+      await triggerSlidingWindow(manager, mockAgent)
 
       expect(mockAgent.messages).toHaveLength(2)
     })
 
-    it('skips reduction when message count equals window size', () => {
+    it('skips reduction when message count equals window size', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 2 })
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Message 1')] }),
         new Message({ role: 'assistant', content: [new TextBlock('Response 1')] }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.applyManagement(mockAgent)
+      await triggerSlidingWindow(manager, mockAgent)
 
       expect(mockAgent.messages).toHaveLength(2)
     })
 
-    it('calls reduceContext when message count exceeds window size', () => {
+    it('calls reduceContext when message count exceeds window size', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 2 })
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Message 1')] }),
         new Message({ role: 'assistant', content: [new TextBlock('Response 1')] }),
         new Message({ role: 'user', content: [new TextBlock('Message 2')] }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.applyManagement(mockAgent)
+      await triggerSlidingWindow(manager, mockAgent)
 
       // Should have trimmed to window size
       expect(mockAgent.messages).toHaveLength(2)
@@ -71,7 +92,7 @@ describe('SlidingWindowConversationManager', () => {
   })
 
   describe('reduceContext - tool result truncation', () => {
-    it('truncates tool results when shouldTruncateResults is true', () => {
+    it('truncates tool results when shouldTruncateResults is true', async () => {
       const manager = new SlidingWindowConversationManager({ shouldTruncateResults: true })
       const messages = [
         new Message({
@@ -85,16 +106,16 @@ describe('SlidingWindowConversationManager', () => {
           ],
         }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.reduceContext(mockAgent)
+      await triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
 
       const toolResult = messages[0]!.content[0]! as ToolResultBlock
       expect(toolResult.status).toBe('error')
       expect(toolResult.content[0]).toEqual({ type: 'textBlock', text: 'The tool result was too large!' })
     })
 
-    it('finds last message with tool results', () => {
+    it('finds last message with tool results', async () => {
       const manager = new SlidingWindowConversationManager({ shouldTruncateResults: true })
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Message 1')] }),
@@ -120,9 +141,9 @@ describe('SlidingWindowConversationManager', () => {
           ],
         }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.reduceContext(mockAgent)
+      await triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
 
       // Should truncate the last message with tool results (index 3)
       const lastToolResult = messages[3]!.content[0]! as ToolResultBlock
@@ -135,7 +156,7 @@ describe('SlidingWindowConversationManager', () => {
       expect(firstToolResult.content[0]).toEqual({ type: 'textBlock', text: 'First result' })
     })
 
-    it('returns after successful truncation without trimming messages', () => {
+    it('returns after successful truncation without trimming messages', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 2, shouldTruncateResults: true })
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Message 1')] }),
@@ -151,15 +172,15 @@ describe('SlidingWindowConversationManager', () => {
           ],
         }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.reduceContext(mockAgent)
+      await triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
 
       // Should not have removed any messages, only truncated tool result
       expect(mockAgent.messages).toHaveLength(3)
     })
 
-    it('skips truncation when shouldTruncateResults is false', () => {
+    it('skips truncation when shouldTruncateResults is false', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 2, shouldTruncateResults: false })
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Message 1')] }),
@@ -175,9 +196,9 @@ describe('SlidingWindowConversationManager', () => {
           ],
         }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.reduceContext(mockAgent)
+      await triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
 
       // Should have trimmed messages instead of truncating tool result
       expect(mockAgent.messages).toHaveLength(2)
@@ -187,7 +208,7 @@ describe('SlidingWindowConversationManager', () => {
       expect(toolResult.status).toBe('success')
     })
 
-    it('does not truncate already-truncated results', () => {
+    it('does not truncate already-truncated results', async () => {
       const manager = new SlidingWindowConversationManager({ shouldTruncateResults: true })
       const messages = [
         new Message({
@@ -223,7 +244,7 @@ describe('SlidingWindowConversationManager', () => {
       ]
       const mockAgent = { messages: messages2 } as unknown as Agent
 
-      manager.reduceContext(mockAgent)
+      await triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
 
       // Should have trimmed messages since truncation was skipped
       expect(mockAgent.messages.length).toBeLessThan(3)
@@ -231,7 +252,7 @@ describe('SlidingWindowConversationManager', () => {
   })
 
   describe('reduceContext - message trimming', () => {
-    it('trims oldest messages when tool results cannot be truncated', () => {
+    it('trims oldest messages when tool results cannot be truncated', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 3, shouldTruncateResults: false })
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Message 1')] }),
@@ -240,15 +261,15 @@ describe('SlidingWindowConversationManager', () => {
         new Message({ role: 'assistant', content: [new TextBlock('Response 2')] }),
         new Message({ role: 'user', content: [new TextBlock('Message 3')] }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.reduceContext(mockAgent)
+      await triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
 
       expect(mockAgent.messages).toHaveLength(3)
       expect(mockAgent.messages[0]!.content[0]!).toEqual({ type: 'textBlock', text: 'Message 2' })
     })
 
-    it('calculates correct trim index (messages.length - windowSize)', () => {
+    it('calculates correct trim index (messages.length - windowSize)', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 2 })
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Message 1')] }),
@@ -256,30 +277,30 @@ describe('SlidingWindowConversationManager', () => {
         new Message({ role: 'user', content: [new TextBlock('Message 2')] }),
         new Message({ role: 'assistant', content: [new TextBlock('Response 2')] }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.reduceContext(mockAgent)
+      await triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
 
       // Should remove 2 messages (4 - 2 = 2)
       expect(mockAgent.messages).toHaveLength(2)
     })
 
-    it('uses default trim index of 2 when messages <= windowSize', () => {
+    it('uses default trim index of 2 when messages <= windowSize', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 5 })
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Message 1')] }),
         new Message({ role: 'assistant', content: [new TextBlock('Response 1')] }),
         new Message({ role: 'user', content: [new TextBlock('Message 2')] }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.reduceContext(mockAgent)
+      await triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
 
       // Should remove 2 messages (default when count <= windowSize)
       expect(mockAgent.messages).toHaveLength(1)
     })
 
-    it('removes messages from start of array using splice', () => {
+    it('removes messages from start of array using splice', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 2 })
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Message 1')] }),
@@ -287,9 +308,9 @@ describe('SlidingWindowConversationManager', () => {
         new Message({ role: 'user', content: [new TextBlock('Message 2')] }),
         new Message({ role: 'assistant', content: [new TextBlock('Response 2')] }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.reduceContext(mockAgent)
+      await triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
 
       // Should keep last 2 messages
       expect(mockAgent.messages).toHaveLength(2)
@@ -299,7 +320,7 @@ describe('SlidingWindowConversationManager', () => {
   })
 
   describe('reduceContext - tool pair validation', () => {
-    it('does not trim at index where oldest message is toolResult', () => {
+    it('does not trim at index where oldest message is toolResult', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 2, shouldTruncateResults: false })
       const messages = [
         new Message({
@@ -319,9 +340,9 @@ describe('SlidingWindowConversationManager', () => {
         new Message({ role: 'assistant', content: [new TextBlock('Response')] }),
         new Message({ role: 'user', content: [new TextBlock('Message')] }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.reduceContext(mockAgent)
+      await triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
 
       // Should not trim at index 1 (toolResult), should trim at index 2 instead
       // This means keeping last 2 messages
@@ -329,7 +350,7 @@ describe('SlidingWindowConversationManager', () => {
       expect(mockAgent.messages[0]!.content[0]!).toEqual({ type: 'textBlock', text: 'Response' })
     })
 
-    it('does not trim at index where oldest message is toolUse without following toolResult', () => {
+    it('does not trim at index where oldest message is toolUse without following toolResult', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 2, shouldTruncateResults: false })
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Message 1')] }),
@@ -340,16 +361,16 @@ describe('SlidingWindowConversationManager', () => {
         new Message({ role: 'assistant', content: [new TextBlock('Response')] }), // Not a toolResult
         new Message({ role: 'user', content: [new TextBlock('Message 2')] }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.reduceContext(mockAgent)
+      await triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
 
       // Should skip index 1 (toolUse without following toolResult), trim at index 2
       expect(mockAgent.messages).toHaveLength(2)
       expect(mockAgent.messages[0]!.content[0]!).toEqual({ type: 'textBlock', text: 'Response' })
     })
 
-    it('allows trim when oldest message is toolUse with following toolResult', () => {
+    it('allows trim when oldest message is toolUse with following toolResult', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 2, shouldTruncateResults: false })
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Message 1')] }),
@@ -370,9 +391,9 @@ describe('SlidingWindowConversationManager', () => {
         new Message({ role: 'assistant', content: [new TextBlock('Response')] }),
         new Message({ role: 'user', content: [new TextBlock('Message 2')] }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.reduceContext(mockAgent)
+      await triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
 
       // Should trim at index 3 (5 - 2 = 3)
       // Index 1 would be toolUse (valid start since toolResult follows)
@@ -384,7 +405,7 @@ describe('SlidingWindowConversationManager', () => {
       expect(mockAgent.messages[1]!.content[0]!).toEqual({ type: 'textBlock', text: 'Message 2' })
     })
 
-    it('allows trim at toolUse when toolResult immediately follows', () => {
+    it('allows trim at toolUse when toolResult immediately follows', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 3, shouldTruncateResults: false })
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Message 1')] }),
@@ -405,9 +426,9 @@ describe('SlidingWindowConversationManager', () => {
         }),
         new Message({ role: 'assistant', content: [new TextBlock('Response 2')] }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.reduceContext(mockAgent)
+      await triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
 
       // Should trim at index 2 (5 - 3 = 2)
       // Index 2 is toolUse with toolResult at index 3 - this is valid
@@ -426,23 +447,23 @@ describe('SlidingWindowConversationManager', () => {
       })
     })
 
-    it('allows trim when oldest message is text or other non-tool content', () => {
+    it('allows trim when oldest message is text or other non-tool content', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 2 })
       const messages = [
         new Message({ role: 'user', content: [new TextBlock('Message 1')] }),
         new Message({ role: 'assistant', content: [new TextBlock('Response 1')] }),
         new Message({ role: 'user', content: [new TextBlock('Message 2')] }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      manager.reduceContext(mockAgent)
+      await triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
 
       // Should trim at index 1 (3 - 2 = 1)
       expect(mockAgent.messages).toHaveLength(2)
       expect(mockAgent.messages[0]!.content[0]).toEqual({ type: 'textBlock', text: 'Response 1' })
     })
 
-    it('throws ContextWindowOverflowError when no valid trim point exists', () => {
+    it('throws ContextWindowOverflowError when no valid trim point exists', async () => {
       const manager = new SlidingWindowConversationManager({ windowSize: 0, shouldTruncateResults: false })
       const messages = [
         new Message({
@@ -456,11 +477,11 @@ describe('SlidingWindowConversationManager', () => {
           ],
         }),
       ]
-      const mockAgent = { messages } as Agent
+      const mockAgent = createMockAgent({ messages })
 
-      expect(() => {
-        manager.reduceContext(mockAgent)
-      }).toThrow(ContextWindowOverflowError)
+      await expect(
+        triggerContextOverflow(manager, mockAgent, new ContextWindowOverflowError('Context overflow'))
+      ).rejects.toThrow(ContextWindowOverflowError)
     })
   })
 
diff --git a/src/conversation-manager/conversation-manager.ts b/src/conversation-manager/conversation-manager.ts
deleted file mode 100644
index beba1667..00000000
--- a/src/conversation-manager/conversation-manager.ts
+++ /dev/null
@@ -1,77 +0,0 @@
-/**
- * Abstract interface for conversation history management.
- *
- * This module provides the base class for implementing conversation management strategies
- * to control the size of message arrays, helping to manage memory usage, control context
- * length, and maintain relevant conversation state.
- */
-
-import type { Message } from '../types/messages.js'
-
-/**
- * Interface for conversation context that can be managed.
- *
- * This interface defines the minimal set of properties required by conversation managers
- * to perform their operations. Using an interface allows for backwards-compatible
- * API evolution and better decoupling from specific implementations.
- */
-export interface ConversationContext {
-  /**
-   * The conversation history of messages that will be managed.
-   * This array is modified in-place by conversation management operations.
-   */
-  messages: Message[]
-}
-
-/**
- * Abstract base class for managing conversation history.
- *
- * This class provides an interface for implementing conversation management strategies
- * to control the size of message arrays/conversation histories, helping to:
- *
- * - Manage memory usage
- * - Control context length
- * - Maintain relevant conversation state
- */
-export abstract class ConversationManager {
-  /**
-   * Creates a new ConversationManager instance.
-   */
-  constructor() {}
-
-  /**
-   * Applies management strategy to the provided conversation context.
-   *
-   * Processes the conversation history to maintain appropriate size by modifying
-   * the messages list in-place. Implementations should handle message pruning,
-   * summarization, or other size management techniques to keep the conversation
-   * context within desired bounds.
-   *
-   * @param context - The conversation context whose message history will be managed.
-   *                  The messages array is modified in-place.
-   */
-  public abstract applyManagement(context: ConversationContext): void
-
-  /**
-   * Called when the model's context window is exceeded.
-   *
-   * This method should implement the specific strategy for reducing the window size
-   * when a context overflow occurs. It is typically called after a ContextWindowOverflowError
-   * is caught during model invocation.
-   *
-   * Implementations might use strategies such as:
-   * - Removing the N oldest messages
-   * - Summarizing older context
-   * - Applying importance-based filtering
-   * - Maintaining critical conversation markers
-   *
-   * @param context - The conversation context whose message history will be reduced.
-   *                  The messages array is modified in-place.
-   * @param error - The error that triggered the context reduction, if any.
-   *
-   * @throws ContextWindowOverflowError If the context cannot be reduced further,
-   *         such as when the conversation is already minimal or when tool result
-   *         messages cannot be properly converted.
-   */
-  public abstract reduceContext(context: ConversationContext, error?: Error): void
-}
diff --git a/src/conversation-manager/index.ts b/src/conversation-manager/index.ts
index d0ff0586..b702c02f 100644
--- a/src/conversation-manager/index.ts
+++ b/src/conversation-manager/index.ts
@@ -1,10 +1,9 @@
 /**
  * Conversation Manager exports.
  *
- * This module exports all conversation manager implementations and types.
+ * This module exports conversation manager implementations.
  */
 
-export { ConversationManager, type ConversationContext } from './conversation-manager.js'
 export { NullConversationManager } from './null-conversation-manager.js'
 export {
   SlidingWindowConversationManager,
diff --git a/src/conversation-manager/null-conversation-manager.ts b/src/conversation-manager/null-conversation-manager.ts
index 12f65dff..a853b1a7 100644
--- a/src/conversation-manager/null-conversation-manager.ts
+++ b/src/conversation-manager/null-conversation-manager.ts
@@ -2,45 +2,25 @@
  * Null implementation of conversation management.
  *
  * This module provides a no-op conversation manager that does not modify
- * the conversation history, useful for testing and scenarios where conversation
+ * the conversation history. Useful for testing and scenarios where conversation
  * management is handled externally.
  */
 
-import { ContextWindowOverflowError } from '../errors.js'
-import { ConversationManager, type ConversationContext } from './conversation-manager.js'
+import type { HookProvider } from '../hooks/types.js'
+import type { HookRegistry } from '../hooks/registry.js'
 
 /**
  * A no-op conversation manager that does not modify the conversation history.
- *
+ * Implements HookProvider but registers zero hooks.
  */
-export class NullConversationManager extends ConversationManager {
-  /**
-   * Does nothing to the conversation history.
-   *
-   * @param _context - The conversation context whose message history will remain unmodified.
-   */
-  public applyManagement(_context: ConversationContext): void {
-    // No-op
-  }
-
+export class NullConversationManager implements HookProvider {
   /**
-   * Does not reduce context and raises an exception.
-   *
-   * If an error is provided, re-throws it. Otherwise, throws a new
-   * ContextWindowOverflowError indicating that the context window has
-   * overflowed and cannot be reduced.
-   *
-   * @param _context - The conversation context whose message history will remain unmodified.
-   * @param error - The error that triggered the context reduction, if any.
+   * Registers callbacks with the hook registry.
+   * This implementation registers no hooks, providing a complete no-op behavior.
    *
-   * @throws Error The provided error if one was given.
-   * @throws ContextWindowOverflowError If no error was provided.
+   * @param _registry - The hook registry to register callbacks with (unused)
    */
-  public reduceContext(_context: ConversationContext, error?: Error): void {
-    if (error) {
-      throw error
-    } else {
-      throw new ContextWindowOverflowError('Context window overflowed!')
-    }
+  public registerCallbacks(_registry: HookRegistry): void {
+    // No-op - register zero hooks
   }
 }
diff --git a/src/conversation-manager/sliding-window-conversation-manager.ts b/src/conversation-manager/sliding-window-conversation-manager.ts
index 0f4a519f..081900f7 100644
--- a/src/conversation-manager/sliding-window-conversation-manager.ts
+++ b/src/conversation-manager/sliding-window-conversation-manager.ts
@@ -7,7 +7,9 @@
 
 import { ContextWindowOverflowError } from '../errors.js'
 import { Message, TextBlock, ToolResultBlock } from '../types/messages.js'
-import { ConversationManager, type ConversationContext } from './conversation-manager.js'
+import type { HookProvider } from '../hooks/types.js'
+import type { HookRegistry } from '../hooks/registry.js'
+import { AfterInvocationEvent, AfterModelCallEvent } from '../hooks/events.js'
 
 /**
  * Configuration for the sliding window conversation manager.
@@ -33,8 +35,12 @@ export type SlidingWindowConversationManagerConfig = {
  * tool usage pairs and avoids invalid window states. When the message count exceeds
  * the window size, it will either truncate large tool results or remove the oldest
  * messages while ensuring tool use/result pairs remain valid.
+ *
+ * As a HookProvider, it registers callbacks for:
+ * - AfterInvocationEvent: Applies sliding window management after each invocation
+ * - AfterModelCallEvent: Reduces context on overflow errors and requests retry
  */
-export class SlidingWindowConversationManager extends ConversationManager {
+export class SlidingWindowConversationManager implements HookProvider {
   private readonly _windowSize: number
   private readonly _shouldTruncateResults: boolean
 
@@ -44,28 +50,49 @@ export class SlidingWindowConversationManager extends ConversationManager {
    * @param config - Configuration options for the sliding window manager.
    */
   constructor(config?: SlidingWindowConversationManagerConfig) {
-    super()
     this._windowSize = config?.windowSize ?? 40
     this._shouldTruncateResults = config?.shouldTruncateResults ?? true
   }
 
   /**
-   * Apply the sliding window to the conversation context's messages array to maintain a manageable history size.
+   * Registers callbacks with the hook registry.
+   *
+   * Registers:
+   * - AfterInvocationEvent callback to apply sliding window management
+   * - AfterModelCallEvent callback to handle context overflow and request retry
+   *
+   * @param registry - The hook registry to register callbacks with
+   */
+  public registerCallbacks(registry: HookRegistry): void {
+    // Apply sliding window management after each invocation
+    registry.addCallback(AfterInvocationEvent, (event) => {
+      this.applyManagement(event.agent.messages)
+    })
+
+    // Handle context overflow errors
+    registry.addCallback(AfterModelCallEvent, (event) => {
+      if (event.error instanceof ContextWindowOverflowError) {
+        this.reduceContext(event.agent.messages, event.error)
+        event.retryModelCall = true
+      }
+    })
+  }
+
+  /**
+   * Apply the sliding window to the messages array to maintain a manageable history size.
    *
    * This method is called after every event loop cycle to apply a sliding window if the message
    * count exceeds the window size. If the number of messages is within the window size, no action
    * is taken.
    *
-   * @param context - The conversation context whose messages will be managed. The messages array is modified in-place.
+   * @param messages - The message array to manage. Modified in-place.
    */
-  public applyManagement(context: ConversationContext): void {
-    const messages = context.messages
-
+  private applyManagement(messages: Message[]): void {
     if (messages.length <= this._windowSize) {
       return
     }
 
-    this.reduceContext(context)
+    this.reduceContext(messages)
   }
 
   /**
@@ -80,15 +107,13 @@ export class SlidingWindowConversationManager extends ConversationManager {
    * 2. If truncation is not possible or doesn't help, trim oldest messages
    * 3. When trimming, skip invalid trim points (toolResult at start, or toolUse without following toolResult)
    *
-   * @param context - The conversation context whose messages will be reduced. The messages array is modified in-place.
+   * @param messages - The message array to reduce. Modified in-place.
    * @param _error - The error that triggered the context reduction, if any.
    *
    * @throws ContextWindowOverflowError If the context cannot be reduced further,
    *         such as when the conversation is already minimal or when no valid trim point exists.
    */
-  public reduceContext(context: ConversationContext, _error?: Error): void {
-    const messages = context.messages
-
+  private reduceContext(messages: Message[], _error?: Error): void {
     // Try to truncate the tool result first
     const lastMessageIdxWithToolResults = this.findLastMessageWithToolResults(messages)
     if (lastMessageIdxWithToolResults !== undefined && this._shouldTruncateResults) {
diff --git a/src/hooks/__tests__/events.test.ts b/src/hooks/__tests__/events.test.ts
index acc64fd7..132456d2 100644
--- a/src/hooks/__tests__/events.test.ts
+++ b/src/hooks/__tests__/events.test.ts
@@ -268,6 +268,31 @@ describe('AfterModelCallEvent', () => {
     const event = new AfterModelCallEvent({ agent, stopData: response })
     expect(event._shouldReverseCallbacks()).toBe(true)
   })
+
+  it('allows retryModelCall to be set when error is present', () => {
+    const agent = new Agent()
+    const error = new Error('Model failed')
+    const event = new AfterModelCallEvent({ agent, error })
+
+    // Initially undefined
+    expect(event.retryModelCall).toBeUndefined()
+
+    // Can be set to true
+    event.retryModelCall = true
+    expect(event.retryModelCall).toBe(true)
+
+    // Can be set to false
+    event.retryModelCall = false
+    expect(event.retryModelCall).toBe(false)
+  })
+
+  it('retryModelCall is optional and defaults to undefined', () => {
+    const agent = new Agent()
+    const error = new Error('Model failed')
+    const event = new AfterModelCallEvent({ agent, error })
+
+    expect(event.retryModelCall).toBeUndefined()
+  })
 })
 
 describe('ModelStreamEventHook', () => {
diff --git a/src/hooks/events.ts b/src/hooks/events.ts
index 9aef9e56..f482cc59 100644
--- a/src/hooks/events.ts
+++ b/src/hooks/events.ts
@@ -175,6 +175,13 @@ export class AfterModelCallEvent extends HookEvent {
   readonly stopData?: ModelStopData
   readonly error?: Error
 
+  /**
+   * Optional flag that can be set by hook callbacks to request a retry of the model call.
+   * Only valid when an error is present. When set to true, the agent will retry the model invocation.
+   * Typically used after reducing context size in response to a ContextWindowOverflowError.
+   */
+  retryModelCall?: boolean
+
   constructor(data: { agent: AgentData; stopData?: ModelStopData; error?: Error }) {
     super()
     this.agent = data.agent
diff --git a/src/index.ts b/src/index.ts
index fff11141..e364f63c 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -119,7 +119,6 @@ export {
 export type { HookCallback, HookProvider, HookEventConstructor, ModelStopResponse } from './hooks/index.js'
 
 // Conversation Manager
-export { ConversationManager } from './conversation-manager/conversation-manager.js'
 export { NullConversationManager } from './conversation-manager/null-conversation-manager.js'
 export {
   SlidingWindowConversationManager,
diff --git a/src/types/agent.ts b/src/types/agent.ts
index 9c3e99a6..147a53a4 100644
--- a/src/types/agent.ts
+++ b/src/types/agent.ts
@@ -10,6 +10,11 @@ export interface AgentData {
    * Agent state storage accessible to tools and application logic.
    */
   state: AgentState
+
+  /**
+   * The conversation history of messages between user and assistant.
+   */
+  messages: Message[]
 }
 
 /**
diff --git a/vended_tools/bash/__tests__/bash.test.ts b/vended_tools/bash/__tests__/bash.test.ts
index ffd6a3ef..e8f40c04 100644
--- a/vended_tools/bash/__tests__/bash.test.ts
+++ b/vended_tools/bash/__tests__/bash.test.ts
@@ -16,7 +16,7 @@ describe.skipIf(!isNode || process.platform === 'win32')('bash tool', () => {
         toolUseId: 'test-id',
         input: {},
       },
-      agent: { state },
+      agent: { state, messages: [] },
     }
     return { state, context }
   }
diff --git a/vended_tools/file_editor/__tests__/file-editor.test.ts b/vended_tools/file_editor/__tests__/file-editor.test.ts
index f2443d59..a2b1f50c 100644
--- a/vended_tools/file_editor/__tests__/file-editor.test.ts
+++ b/vended_tools/file_editor/__tests__/file-editor.test.ts
@@ -19,7 +19,7 @@ describe('fileEditor tool', () => {
         toolUseId: 'test-id',
         input: {},
       },
-      agent: { state: agentState },
+      agent: { state: agentState, messages: [] },
     }
     return { state: agentState, context: toolContext }
   }
diff --git a/vended_tools/notebook/__tests__/notebook.test.ts b/vended_tools/notebook/__tests__/notebook.test.ts
index 813bdd27..a5273c69 100644
--- a/vended_tools/notebook/__tests__/notebook.test.ts
+++ b/vended_tools/notebook/__tests__/notebook.test.ts
@@ -14,7 +14,7 @@ describe('notebook tool', () => {
         toolUseId: 'test-id',
         input: {},
       },
-      agent: { state },
+      agent: { state, messages: [] },
     }
     return { state, context }
   }