Phase 5.5-5.9: Plugin-Marketplace, Agent Memory, GraphRAG, Subagents, External Agent API

5.5 Plugin-Marketplace:
- New plugin: marketplace/ (models, routes, services, schemas, config)
- MarketplaceListing model (global, no tenant_id)
- Ed25519 signature verification via PluginSignature
- Endpoints: list, detail, install, verify, categories
- Config: MARKETPLACE_SERVER_URL setting

5.6 Agent Memory (persistent):
- New plugin: agent_memory/ (models, routes, services, schemas)
- AgentMemory model with embedding vector(768) + HNSW index
- store_memory() with auto-embedding
- retrieve_relevant_memories() with pgvector cosine similarity
- Semantic search endpoint

5.7 GraphRAG:
- New plugin: graph_rag/ (models, routes, services, provider, schemas)
- EntityRelationship model (source/target type+id, relationship_type, metadata)
- BFS graph traversal (bidirectional, configurable depth)
- GraphRAGSearchProvider registered in unified_search

5.8 Subagents / Multi-Agent:
- AgentCoordinator class (create_subtask, wait_for_subtask, aggregate, cancel)
- AgentSubtask model + migration 0002_agent_subtasks.sql
- 6 new API endpoints for subtask management
- Tools registered in AI tool registry

5.9 External Agent API:
- external_api.py: POST /run, GET /status, POST /stream (SSE)
- Bearer API token authentication
- Rate limiting: 10 req/min per token
- ExternalAgentRequest/Response schemas

3 new plugins registered in main.py and __init__.py
All files py_compile clean

app/plugins/builtins/marketplace/models.py

@@ -0,0 +1,85 @@
+"""Marketplace plugin — SQLAlchemy models for marketplace listings."""
+
+from __future__ import annotations
+
+import uuid
+from datetime import UTC, datetime
+
+from sqlalchemy import DateTime, Float, Index, Integer, String, Text
+from sqlalchemy.dialects.postgresql import JSONB, UUID as PGUUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.db import Base, TimestampMixin
+
+
+class MarketplaceListing(Base, TimestampMixin):
+    """Marketplace listing for a plugin.
+
+    This table is NOT tenant-scoped — marketplace listings are global.
+    """
+
+    __tablename__ = "marketplace_listings"
+    __table_args__ = (
+        Index("ix_marketplace_listings_name", "name", unique=True),
+        Index("ix_marketplace_listings_tags", "tags", postgresql_using="gin"),
+        Index("ix_marketplace_listings_is_verified", "is_verified"),
+        Index("ix_marketplace_listings_download_count", "download_count"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    name: Mapped[str] = mapped_column(
+        String(80), nullable=False, unique=True, comment="Unique plugin identifier (snake_case)"
+    )
+    display_name: Mapped[str] = mapped_column(
+        String(120), nullable=False, comment="Human-readable plugin name"
+    )
+    description: Mapped[str] = mapped_column(
+        Text, nullable=False, default="", comment="Plugin description"
+    )
+    version: Mapped[str] = mapped_column(
+        String(40), nullable=False, comment="Latest available version (SemVer)"
+    )
+    author: Mapped[str] = mapped_column(
+        String(200), nullable=False, default="", comment="Plugin author name"
+    )
+    homepage: Mapped[str] = mapped_column(
+        String(500), nullable=False, default="", comment="Plugin homepage URL"
+    )
+    download_url: Mapped[str] = mapped_column(
+        String(1024), nullable=False, comment="URL to download the plugin ZIP"
+    )
+    signature_public_key: Mapped[str] = mapped_column(
+        Text, nullable=False, default="", comment="Ed25519 public key for signature verification"
+    )
+    icon: Mapped[str] = mapped_column(
+        String(500), nullable=False, default="", comment="Icon URL or emoji"
+    )
+    screenshots: Mapped[list] = mapped_column(
+        JSONB, nullable=False, default=list, comment="List of screenshot URLs"
+    )
+    tags: Mapped[list] = mapped_column(
+        JSONB, nullable=False, default=list, comment="List of category tags"
+    )
+    price: Mapped[float] = mapped_column(
+        Float, nullable=False, default=0.0, comment="Price in EUR (0 = free)"
+    )
+    is_verified: Mapped[bool] = mapped_column(
+        nullable=False, default=False, comment="Whether the plugin is verified by LeoCRM"
+    )
+    download_count: Mapped[int] = mapped_column(
+        Integer, nullable=False, default=0, comment="Number of downloads"
+    )
+    min_app_version: Mapped[str] = mapped_column(
+        String(40), nullable=False, default="0.0.0", comment="Minimum LeoCRM version required"
+    )
+    license: Mapped[str] = mapped_column(
+        String(50), nullable=False, default="MIT", comment="License identifier"
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        nullable=False,
+        default=lambda: datetime.now(UTC),
+        onupdate=lambda: datetime.now(UTC),
+    )