diff --git a/src/core/messenger/messenger-config.yaml b/src/core/messenger/messenger-config.yaml
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+# Inter-Agent Messenger Configuration
+# Enables formal handoff protocols between agents
+
+name: inter-agent-messenger
+version: "1.0.0"
+description: "Formal handoff and communication protocols between BMAD agents"
+
+# Message queue location
+queue_dir: "{project-root}/_bmad-output/messenger"
+queue_file: "{queue_dir}/message-queue.yaml"
+archive_dir: "{queue_dir}/archive"
+
+# Message types
+message_types:
+  handoff:
+    description: "Transfer work from one agent to another"
+    required_fields:
+      - from_agent
+      - to_agent
+      - artifact_path
+      - context_summary
+      - next_actions
+    priority: high
+
+  review:
+    description: "Request review of completed work"
+    required_fields:
+      - from_agent
+      - to_agent
+      - artifact_path
+      - review_type
+    priority: medium
+
+  clarify:
+    description: "Request clarification on requirements or decisions"
+    required_fields:
+      - from_agent
+      - to_agent
+      - question
+      - context
+    priority: high
+
+  escalate:
+    description: "Escalate issue to user attention"
+    required_fields:
+      - from_agent
+      - issue
+      - severity
+      - recommendation
+    priority: critical
+
+  notify:
+    description: "Inform other agents of status or decisions"
+    required_fields:
+      - from_agent
+      - to_agents  # Can be list or "all"
+      - message
+    priority: low
+
+  collaborate:
+    description: "Request collaborative input from multiple agents"
+    required_fields:
+      - from_agent
+      - to_agents
+      - topic
+      - deadline
+    priority: medium
+
+# Standard routing rules
+routing:
+  # Phase 1 → Phase 2 handoffs
+  analyst_to_pm:
+    trigger: "Product brief complete"
+    from: analyst
+    to: pm
+    payload:
+      - product_brief_path
+      - key_insights
+      - recommended_priorities
+
+  pm_to_architect:
+    trigger: "PRD complete"
+    from: pm
+    to: architect
+    payload:
+      - prd_path
+      - priority_features
+      - technical_constraints
+      - timeline_expectations
+
+  pm_to_ux:
+    trigger: "PRD complete with UI"
+    from: pm
+    to: ux-designer
+    payload:
+      - prd_path
+      - user_personas
+      - key_user_flows
+
+  # Phase 2 → Phase 3 handoffs
+  architect_to_sm:
+    trigger: "Architecture approved"
+    from: architect
+    to: sm
+    payload:
+      - architecture_path
+      - tech_decisions
+      - component_boundaries
+      - api_contracts
+
+  ux_to_sm:
+    trigger: "UX design complete"
+    from: ux-designer
+    to: sm
+    payload:
+      - ux_design_path
+      - component_library
+      - interaction_patterns
+
+  # Phase 3 → Phase 4 handoffs
+  sm_to_dev:
+    trigger: "Story ready for dev"
+    from: sm
+    to: dev
+    payload:
+      - story_path
+      - acceptance_criteria
+      - technical_notes
+      - dependencies
+
+  dev_to_tea:
+    trigger: "Implementation complete"
+    from: dev
+    to: tea
+    payload:
+      - story_path
+      - files_changed
+      - test_coverage
+      - review_request
+
+  # Review flows
+  tea_to_dev:
+    trigger: "Review complete with issues"
+    from: tea
+    to: dev
+    payload:
+      - review_findings
+      - severity_breakdown
+      - required_actions
+
+# Priority levels
+priorities:
+  critical: 1
+  high: 2
+  medium: 3
+  low: 4
+
+# Message retention
+retention:
+  active_messages_max: 100
+  archive_after_days: 7
+  delete_archived_after_days: 30
diff --git a/src/core/messenger/messenger.md b/src/core/messenger/messenger.md
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+# Inter-Agent Messenger System
+
+## Overview
+
+The Inter-Agent Messenger enables formal handoff protocols between BMAD agents. It provides structured communication for work transitions, review requests, clarifications, and escalations.
+
+## Architecture
+
+```
+┌─────────────┐    ┌─────────────────┐    ┌─────────────┐
+│   Agent A   │───▶│  Message Queue  │───▶│   Agent B   │
+│  (sender)   │    │  (YAML file)    │    │ (receiver)  │
+└─────────────┘    └─────────────────┘    └─────────────┘
+                           │
+                           ▼
+                   ┌─────────────┐
+                   │   Archive   │
+                   └─────────────┘
+```
+
+## Message Types
+
+### handoff
+Transfer work from one agent to another with full context.
+
+**Example:**
+```yaml
+type: handoff
+from: pm
+to: architect
+payload:
+  artifact_path: "_bmad-output/planning-artifacts/prd.md"
+  context_summary: "PRD complete for user auth feature"
+  next_actions:
+    - Review technical requirements
+    - Identify infrastructure needs
+    - Propose architecture patterns
+```
+
+### review
+Request review of completed work.
+
+**Example:**
+```yaml
+type: review
+from: dev
+to: tea
+payload:
+  artifact_path: "_bmad-output/implementation-artifacts/stories/1-2-user-login.md"
+  review_type: "code-review"
+  files_changed:
+    - src/auth/login.ts
+    - src/auth/login.test.ts
+```
+
+### clarify
+Request clarification on requirements or decisions.
+
+**Example:**
+```yaml
+type: clarify
+from: dev
+to: architect
+payload:
+  question: "Should authentication use JWT or session cookies?"
+  context: "Story 1-2 requires user login but auth method not specified in architecture"
+```
+
+### escalate
+Escalate issue to user attention (critical).
+
+**Example:**
+```yaml
+type: escalate
+from: dev
+to: user
+payload:
+  issue: "Blocking dependency conflict between React 18 and legacy charting library"
+  severity: "blocker"
+  recommendation: "Either upgrade charting library or downgrade to React 17"
+  impact: "Cannot proceed with Epic 2 until resolved"
+```
+
+### notify
+Inform agents of status or decisions.
+
+**Example:**
+```yaml
+type: notify
+from: architect
+to_agents: all
+payload:
+  message: "Architecture decision: Using PostgreSQL with Prisma ORM"
+  decision_doc: "_bmad-output/planning-artifacts/architecture.md#database"
+```
+
+### collaborate
+Request collaborative input from multiple agents.
+
+**Example:**
+```yaml
+type: collaborate
+from: pm
+to_agents:
+  - architect
+  - ux-designer
+  - tea
+payload:
+  topic: "Feature complexity assessment for real-time collaboration"
+  deadline: "2025-01-16T17:00:00Z"
+  context: "Client requesting WebSocket-based real-time editing"
+```
+
+## Standard Handoff Routes
+
+### Phase 1 → Phase 2
+
+| From | To | Trigger | Payload |
+|------|-----|---------|---------|
+| analyst | pm | Product brief complete | brief_path, key_insights |
+| pm | architect | PRD complete | prd_path, priority_features |
+| pm | ux-designer | PRD with UI complete | prd_path, user_personas |
+
+### Phase 2 → Phase 3
+
+| From | To | Trigger | Payload |
+|------|-----|---------|---------|
+| architect | sm | Architecture approved | architecture_path, tech_decisions |
+| ux-designer | sm | UX design complete | ux_path, component_library |
+
+### Phase 3 → Phase 4
+
+| From | To | Trigger | Payload |
+|------|-----|---------|---------|
+| sm | dev | Story ready | story_path, acceptance_criteria |
+| dev | tea | Implementation complete | story_path, files_changed |
+| tea | dev | Review with issues | review_findings, required_actions |
+
+## Priority Levels
+
+| Priority | Value | Use Case |
+|----------|-------|----------|
+| critical | 1 | Blockers, escalations |
+| high | 2 | Handoffs, clarifications |
+| medium | 3 | Reviews, collaborations |
+| low | 4 | Notifications |
+
+## Usage
+
+### Sending a Message
+
+```xml
+<exec task="send-message">
+  <param name="type">handoff</param>
+  <param name="from_agent">pm</param>
+  <param name="to_agent">architect</param>
+  <param name="payload">
+    artifact_path: "_bmad-output/planning-artifacts/prd.md"
+    context_summary: "PRD complete, ready for architecture"
+    next_actions:
+      - Review technical requirements
+      - Design system architecture
+  </param>
+</exec>
+```
+
+### Receiving Messages
+
+```xml
+<exec task="receive-message">
+  <param name="agent">architect</param>
+  <param name="type_filter">handoff</param>
+</exec>
+```
+
+## Queue File Structure
+
+```yaml
+# _bmad-output/messenger/message-queue.yaml
+messages:
+  - message_id: "MSG-20250115-a1b2"
+    type: "handoff"
+    from: "pm"
+    to: "architect"
+    priority: "high"
+    created: "2025-01-15T10:30:00Z"
+    status: "pending"
+    payload:
+      artifact_path: "_bmad-output/planning-artifacts/prd.md"
+      context_summary: "PRD complete"
+      next_actions:
+        - Review requirements
+        - Design architecture
+
+  - message_id: "MSG-20250115-c3d4"
+    type: "notify"
+    from: "architect"
+    to_agents: "all"
+    priority: "low"
+    created: "2025-01-15T11:00:00Z"
+    status: "read"
+    payload:
+      message: "Using PostgreSQL with Prisma"
+```
+
+## Best Practices
+
+1. **Always include context** - Don't assume receiving agent knows the background
+2. **Use appropriate priority** - Reserve critical for true blockers
+3. **Include artifact paths** - Reference documents, not content
+4. **Specify next actions** - Clear handoff means faster pickup
+5. **Check messages at workflow start** - Agents should check queue before beginning work
diff --git a/src/core/messenger/receive-message.xml b/src/core/messenger/receive-message.xml
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+<?xml version="1.0" encoding="UTF-8"?>
+<task id="receive-message" name="Receive Inter-Agent Message" standalone="false">
+  <description>Receive and process messages from the messenger queue</description>
+
+  <config>
+    <source>{project-root}/_bmad/core/messenger/messenger-config.yaml</source>
+    <queue_file>{project-root}/_bmad-output/messenger/message-queue.yaml</queue_file>
+    <archive_dir>{project-root}/_bmad-output/messenger/archive</archive_dir>
+  </config>
+
+  <parameters>
+    <param name="agent" required="true" description="Agent checking for messages"/>
+    <param name="type_filter" required="false" description="Filter by message type"/>
+    <param name="mark_read" required="false" default="true" description="Mark messages as read"/>
+  </parameters>
+
+  <execution>
+    <step n="1" goal="Load message queue">
+      <action>Load queue from {queue_file}</action>
+      <action if="queue not exists or empty">Return: "No messages in queue"</action>
+    </step>
+
+    <step n="2" goal="Filter messages for agent">
+      <action>Filter messages where:
+        - to == {agent} OR
+        - to_agents contains {agent} OR
+        - to_agents == "all"
+      </action>
+      <action>Filter by status == "pending"</action>
+      <action if="type_filter specified">Filter by type == {type_filter}</action>
+      <action>Sort by priority (critical first), then by created (oldest first)</action>
+    </step>
+
+    <step n="3" goal="Process messages">
+      <action if="no matching messages">Return: "No pending messages for {agent}"</action>
+      <action>For each message:
+        - Display message summary
+        - If mark_read == true, update status to "read"
+      </action>
+    </step>
+
+    <step n="4" goal="Update queue">
+      <action if="mark_read == true">Save updated queue to {queue_file}</action>
+    </step>
+
+    <step n="5" goal="Return messages">
+      <action>Return list of messages with full payloads</action>
+      <output>
+        Messages for {agent}: {count}
+
+        {for each message}
+        ---
+        [{priority}] {type} from {from_agent}
+        ID: {message_id}
+        Received: {created}
+
+        {payload_summary}
+        ---
+        {end for}
+      </output>
+    </step>
+  </execution>
+
+  <output>
+    <field name="messages" description="Array of message objects"/>
+    <field name="count" description="Number of messages"/>
+  </output>
+</task>
diff --git a/src/core/messenger/send-message.xml b/src/core/messenger/send-message.xml
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+++ b/src/core/messenger/send-message.xml
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+<?xml version="1.0" encoding="UTF-8"?>
+<task id="send-message" name="Send Inter-Agent Message" standalone="false">
+  <description>Send a message between BMAD agents using the messenger system</description>
+
+  <config>
+    <source>{project-root}/_bmad/core/messenger/messenger-config.yaml</source>
+    <queue_file>{project-root}/_bmad-output/messenger/message-queue.yaml</queue_file>
+  </config>
+
+  <parameters>
+    <param name="type" required="true" description="Message type: handoff, review, clarify, escalate, notify, collaborate"/>
+    <param name="from_agent" required="true" description="Sending agent identifier"/>
+    <param name="to_agent" required="false" description="Receiving agent (not needed for escalate)"/>
+    <param name="to_agents" required="false" description="List of receiving agents (for notify/collaborate)"/>
+    <param name="payload" required="true" description="Message payload object"/>
+    <param name="priority" required="false" default="medium" description="Message priority"/>
+  </parameters>
+
+  <execution>
+    <step n="1" goal="Validate message type and required fields">
+      <action>Load messenger config from {config_source}</action>
+      <action>Validate type is one of: handoff, review, clarify, escalate, notify, collaborate</action>
+      <action>Check required_fields for message type are present in payload</action>
+      <action if="validation fails">HALT with validation error message</action>
+    </step>
+
+    <step n="2" goal="Create message object">
+      <action>Generate unique message_id: "MSG-{timestamp}-{random4}"</action>
+      <action>Build message object:
+        ```yaml
+        message_id: "{message_id}"
+        type: "{type}"
+        from: "{from_agent}"
+        to: "{to_agent}" or "{to_agents}"
+        priority: "{priority}"
+        created: "{timestamp}"
+        status: "pending"
+        payload: {payload}
+        ```
+      </action>
+    </step>
+
+    <step n="3" goal="Ensure queue directory exists">
+      <action>Check if {queue_dir} exists</action>
+      <action if="not exists">Create directory {queue_dir}</action>
+    </step>
+
+    <step n="4" goal="Add message to queue">
+      <action>Load existing queue from {queue_file} (or create empty if not exists)</action>
+      <action>Append new message to messages array</action>
+      <action>Sort messages by priority (critical first)</action>
+      <action>Save updated queue to {queue_file}</action>
+    </step>
+
+    <step n="5" goal="Return confirmation">
+      <action>Return message_id and status</action>
+      <output>
+        Message sent successfully.
+        ID: {message_id}
+        Type: {type}
+        From: {from_agent}
+        To: {to_agent}
+        Priority: {priority}
+      </output>
+    </step>
+  </execution>
+
+  <output>
+    <field name="message_id" description="Unique message identifier"/>
+    <field name="status" description="sent | failed"/>
+  </output>
+</task>