T11: tags plugin + permissions plugin + entity links backend — 68 tests, 66.61% coverage

.a0/briefings/T11_briefing.md

@@ -0,0 +1,154 @@
+# T11 Briefing — Tags Plugin + Permissions Plugin + Entity Links Backend
+
+## Project Root
+/a0/usr/workdir/dev-projects/leocrm
+
+## Task
+Implement 3 builtin plugins: Tags, Permissions, Entity Links.
+
+## Plugin Framework (existing — read these files first)
+- `app/plugins/base.py` — BasePlugin abstract class with lifecycle hooks
+- `app/plugins/manifest.py` — PluginManifest, PluginRouteDef schemas
+- `app/plugins/registry.py` — PluginRegistry (discovers builtins, manages lifecycle)
+- `app/plugins/builtins/test_sample.py` — Example plugin (reference pattern)
+- `app/plugins/builtins/migrations/` — Migration SQL files go here
+- `app/core/event_bus.py` — EventBus for pub/sub
+- `app/core/service_container.py` — DI container
+- `app/core/db.py` — Base, TenantMixin, TimestampMixin
+- `app/models/company.py` — Company model (reference for model patterns)
+- `app/models/plugin.py` — Plugin + PluginMigration models
+
+## Architecture Rules
+- Plugins live in `app/plugins/builtins/` as subdirectories (e.g. `app/plugins/builtins/tags/`)
+- Each plugin has: `__init__.py` (exports plugin class), `plugin.py` (BasePlugin subclass), `routes.py` (APIRouter), `models.py` (SQLAlchemy models), `schemas.py` (Pydantic schemas), `migrations/` (SQL files)
+- Migrations are plain SQL files in `app/plugins/builtins/<plugin>/migrations/`
+- Models use SQLAlchemy 2.0 style (Mapped, mapped_column) with PGUUID, TenantMixin
+- Routes use FastAPI APIRouter, registered via manifest routes list
+- Events: subscribe in on_activate, handlers named `on_<event_name>`
+
+## 1. Tags Plugin (`app/plugins/builtins/tags/`)
+
+### Requirements (F-TAG-01 through F-TAG-04)
+- Tags can be applied to files, folders, companies, contacts
+- Tags are global (not per-user), centrally managed
+- Multiple tags per entity (N:M)
+- Tag CRUD with color support
+- Tag filtering in lists (AND/OR combination)
+- Tag cloud/sidebar with entity counts
+
+### Endpoints
+```
+GET    /api/v1/tags              → 200, list tags with entity counts
+POST   /api/v1/tags              → 201, create tag (name, color)
+PATCH  /api/v1/tags/{id}          → 200, update tag
+DELETE /api/v1/tags/{id}          → 204, cascade delete assignments
+POST   /api/v1/tags/assign        → 200, assign tag to entity (tag_id, entity_type, entity_id)
+DELETE /api/v1/tags/assign        → 204, remove tag assignment
+POST   /api/v1/tags/bulk-assign   → 200, assign multiple tags to entity
+GET    /api/v1/tags/{id}/entities → 200, list entities with this tag
+```
+
+### Models
+- `Tag`: id (UUID), name (str, unique per tenant), color (str, hex), tenant_id
+- `TagAssignment`: id, tag_id (FK), entity_type (str: company/contact/file/folder), entity_id (UUID), tenant_id
+
+### Migration
+- `0001_initial.sql`: Create `tags` and `tag_assignments` tables with tenant_id columns
+
+## 2. Permissions Plugin (`app/plugins/builtins/permissions/`)
+
+### Requirements (F-PERM-01 through F-PERM-06)
+- Personal root folder per user ("Mein Bereich")
+- Shared root folders for teams/departments
+- Share files/folders with individual users (read/write)
+- Share files/folders with user groups (read/write)
+- Public share links (with password, expiry, download-only or preview+download)
+- Permission display (who has access?)
+
+### Endpoints
+```
+GET    /api/v1/dms/files/{id}/permissions          → 200, permission list
+POST   /api/v1/dms/files/{id}/permissions          → 201, grant permission
+DELETE /api/v1/dms/files/{id}/permissions/{user_id} → 204, revoke
+POST   /api/v1/dms/files/{id}/share-link           → 200, create share link (returns public token URL)
+GET    /api/public/share/{token}                   → 200 (file) or 410 (expired)
+DELETE /api/v1/dms/share-links/{id}                → 204, revoke share link
+```
+
+### Models
+- `Permission`: id, file_id (UUID), user_id (UUID), group_id (UUID nullable), access_level (read/write), tenant_id
+- `ShareLink`: id, file_id (UUID), token (str, unique), password_hash (nullable), expires_at (nullable), access_level (download/preview), tenant_id
+
+### Migration
+- `0001_initial.sql`: Create `permissions` and `share_links` tables
+
+### Special
+- Public share endpoint `/api/public/share/{token}` must NOT require auth
+- Expired links return 410 Gone
+- Password-protected links verify password before serving
+
+## 3. Entity Links Backend (`app/plugins/builtins/entity_links/`)
+
+### Requirements (F-LINK-01 through F-LINK-06)
+- Link files/folders to companies (N:M)
+- Link files/folders to contacts (N:M)
+- Reverse links (file shows linked entities)
+- Multi-links (one file → many entities)
+- Event cleanup: on company.deleted/contact.deleted → remove links
+
+### Endpoints
+```
+POST   /api/v1/dms/files/{id}/link    → 200, link file to entity (entity_type, entity_id)
+DELETE /api/v1/dms/files/{id}/link    → 204, remove link (entity_type, entity_id in body)
+GET    /api/v1/dms/files/{id}/links    → 200, list all linked entities for file
+GET    /api/v1/companies/{id}/files   → 200, list linked files for company
+GET    /api/v1/contacts/{id}/files    → 200, list linked files for contact
+```
+
+### Models
+- `EntityLink`: id, file_id (UUID), entity_type (str: company/contact), entity_id (UUID), tenant_id, created_by (UUID)
+
+### Migration
+- `0001_initial.sql`: Create `entity_links` table
+
+### Event Handling
+- Subscribe to `company.deleted` → delete all EntityLink rows where entity_type='company' AND entity_id=deleted_id
+- Subscribe to `contact.deleted` → delete all EntityLink rows where entity_type='contact' AND entity_id=deleted_id
+
+## Acceptance Criteria (14 total — ALL must pass)
+1. GET /api/v1/dms/files/{id}/permissions → 200 + permission list
+2. POST /api/v1/dms/files/{id}/link → 200, file linked to entity
+3. DELETE /api/v1/dms/files/{id}/link → 204, link removed
+4. POST /api/v1/dms/files/{id}/share-link → 200 + public token URL
+5. GET /api/public/share/{token} with expired link → 410
+6. GET /api/v1/tags → 200 + tags with counts
+7. POST /api/v1/tags → 201, tag created
+8. PATCH /api/v1/tags/{id} → 200
+9. DELETE /api/v1/tags/{id} → 204, cascade delete assignments
+10. POST /api/v1/tags/assign → 200, tag assigned to entity
+11. DELETE /api/v1/tags/assign → 204, tag removed
+12. POST /api/v1/tags/bulk-assign → 200, multiple tags assigned
+13. DMS plugin listens to company.deleted event → linked files cleanup
+14. Folder permissions enforced: user without read → 403
+
+## Test Files (create in `tests/`)
+- `tests/test_tags.py` — Tag CRUD, assignment, bulk assign, cascade delete, counts
+- `tests/test_permissions.py` — Personal root, shared root, share with users/groups, share links (password, expiry), permission display, 403 enforcement
+- `tests/test_entity_links.py` — Link file to company, link to contact, reverse links, multi-links, event cleanup on deletion
+
+## Verification Commands
+```bash
+cd /a0/usr/workdir/dev-projects/leocrm
+python -m pytest tests/test_tags.py tests/test_permissions.py tests/test_entity_links.py -v --tb=short
+python -m pytest tests/test_tags.py tests/test_permissions.py tests/test_entity_links.py --cov=app/plugins/builtins --cov-report=term-missing
+```
+
+## Rules
+- Use text_editor:write for new files, text_editor:patch for updates
+- Read existing files before modifying
+- No Lorem Ipsum, no placeholder code
+- Follow existing patterns (SQLAlchemy 2.0, Pydantic v2, FastAPI APIRouter)
+- Each plugin must have manifest, plugin class, routes, models, schemas, migrations
+- Register plugins in `app/plugins/builtins/__init__.py`
+- Keep response under 50 lines
+- Report: files created, test count + pass/fail, coverage %

app/plugins/builtins/__init__.py

@@ -2,4 +2,13 @@
 
 Each module in this package that exports a BasePlugin subclass will be
 discovered automatically by the plugin registry on application startup.
+
+Subdirectory plugins (tags, permissions, entity_links) export their plugin
+class via __init__.py so the registry can discover them as packages.
 """
+
+from app.plugins.builtins.tags import TagsPlugin
+from app.plugins.builtins.permissions import PermissionsPlugin
+from app.plugins.builtins.entity_links import EntityLinksPlugin
+
+__all__ = ["TagsPlugin", "PermissionsPlugin", "EntityLinksPlugin"]

app/plugins/builtins/entity_links/__init__.py

@@ -0,0 +1,5 @@
+"""Entity Links builtin plugin."""
+
+from app.plugins.builtins.entity_links.plugin import EntityLinksPlugin
+
+__all__ = ["EntityLinksPlugin"]

app/plugins/builtins/entity_links/migrations/0001_initial.sql

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+-- Entity Links plugin initial migration: creates entity_links table
+CREATE TABLE IF NOT EXISTS entity_links (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    file_id UUID NOT NULL,
+    entity_type VARCHAR(20) NOT NULL,
+    entity_id UUID NOT NULL,
+    created_by UUID,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    CONSTRAINT uq_entity_links_file_entity UNIQUE (tenant_id, file_id, entity_type, entity_id)
+);
+CREATE INDEX IF NOT EXISTS ix_entity_links_file ON entity_links(tenant_id, file_id);
+CREATE INDEX IF NOT EXISTS ix_entity_links_entity ON entity_links(tenant_id, entity_type, entity_id);

app/plugins/builtins/entity_links/models.py

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+"""EntityLink model for the Entity Links plugin."""
+
+from __future__ import annotations
+
+import uuid
+
+from sqlalchemy import String, ForeignKey, Index, UniqueConstraint
+from sqlalchemy.dialects.postgresql import UUID as PGUUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.db import Base, TenantMixin
+
+
+class EntityLink(Base, TenantMixin):
+    """N:M link between files/folders and companies/contacts."""
+
+    __tablename__ = "entity_links"
+    __table_args__ = (
+        UniqueConstraint(
+            "tenant_id", "file_id", "entity_type", "entity_id",
+            name="uq_entity_links_file_entity",
+        ),
+        Index("ix_entity_links_file", "tenant_id", "file_id"),
+        Index("ix_entity_links_entity", "tenant_id", "entity_type", "entity_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    file_id: Mapped[uuid.UUID] = mapped_column(PGUUID(as_uuid=True), nullable=False)
+    entity_type: Mapped[str] = mapped_column(String(20), nullable=False)
+    entity_id: Mapped[uuid.UUID] = mapped_column(PGUUID(as_uuid=True), nullable=False)
+    created_by: Mapped[uuid.UUID | None] = mapped_column(
+        PGUUID(as_uuid=True), nullable=True
+    )

app/plugins/builtins/entity_links/plugin.py

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+"""Entity Links plugin — link files to companies/contacts, reverse links, event cleanup."""
+
+from __future__ import annotations
+
+from typing import Any
+
+from app.plugins.base import BasePlugin
+from app.plugins.manifest import PluginManifest, PluginRouteDef
+
+
+class EntityLinksPlugin(BasePlugin):
+    """Entity Links plugin for N:M file-to-entity links with event-driven cleanup."""
+
+    manifest = PluginManifest(
+        name="entity_links",
+        version="1.0.0",
+        display_name="Entity Links",
+        description="Link files to companies/contacts (N:M), reverse links, event cleanup on deletion.",
+        dependencies=[],
+        routes=[
+            PluginRouteDef(
+                path="/api/v1/dms",
+                module="app.plugins.builtins.entity_links.routes",
+                router_attr="router",
+            ),
+            PluginRouteDef(
+                path="/api/v1/companies",
+                module="app.plugins.builtins.entity_links.routes",
+                router_attr="company_router",
+            ),
+            PluginRouteDef(
+                path="/api/v1/contacts",
+                module="app.plugins.builtins.entity_links.routes",
+                router_attr="contact_router",
+            ),
+        ],
+        events=["company.deleted", "contact.deleted"],
+        migrations=["0001_initial.sql"],
+        permissions=[],
+    )
+
+    async def on_company_deleted(self, payload: dict[str, Any]) -> None:
+        """Handle company.deleted event — remove all EntityLink rows for that company."""
+        from sqlalchemy import delete
+        from app.core.db import get_session_factory
+        from app.plugins.builtins.entity_links.models import EntityLink
+
+        entity_id = payload.get("entity_id") or payload.get("company_id")
+        tenant_id = payload.get("tenant_id")
+        if entity_id is None or tenant_id is None:
+            return
+
+        import uuid as _uuid
+        factory = get_session_factory()
+        async with factory() as session:
+            await session.execute(
+                delete(EntityLink).where(
+                    EntityLink.tenant_id == _uuid.UUID(tenant_id),
+                    EntityLink.entity_type == "company",
+                    EntityLink.entity_id == _uuid.UUID(str(entity_id)),
+                )
+            )
+            await session.commit()
+
+    async def on_contact_deleted(self, payload: dict[str, Any]) -> None:
+        """Handle contact.deleted event — remove all EntityLink rows for that contact."""
+        from sqlalchemy import delete
+        from app.core.db import get_session_factory
+        from app.plugins.builtins.entity_links.models import EntityLink
+
+        entity_id = payload.get("entity_id") or payload.get("contact_id")
+        tenant_id = payload.get("tenant_id")
+        if entity_id is None or tenant_id is None:
+            return
+
+        import uuid as _uuid
+        factory = get_session_factory()
+        async with factory() as session:
+            await session.execute(
+                delete(EntityLink).where(
+                    EntityLink.tenant_id == _uuid.UUID(tenant_id),
+                    EntityLink.entity_type == "contact",
+                    EntityLink.entity_id == _uuid.UUID(str(entity_id)),
+                )
+            )
+            await session.commit()

app/plugins/builtins/entity_links/routes.py

@@ -0,0 +1,194 @@
+"""Entity Links plugin routes — link files to companies/contacts, reverse links."""
+
+from __future__ import annotations
+
+import uuid
+
+from fastapi import APIRouter, Body, Depends, HTTPException, Response, status
+from sqlalchemy import select, delete
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.db import get_db
+from app.deps import get_current_user
+from app.plugins.builtins.entity_links.models import EntityLink
+from app.plugins.builtins.entity_links.schemas import EntityLinkRequest
+
+router = APIRouter(prefix="/api/v1/dms", tags=["entity-links"])
+company_router = APIRouter(prefix="/api/v1/companies", tags=["entity-links"])
+contact_router = APIRouter(prefix="/api/v1/contacts", tags=["entity-links"])
+
+VALID_ENTITY_TYPES = {"company", "contact"}
+
+
+def _parse_uuid(val: str, field: str) -> uuid.UUID:
+    try:
+        return uuid.UUID(val)
+    except (ValueError, TypeError):
+        raise HTTPException(400, detail={"detail": f"Invalid {field}", "code": "invalid_id"})
+
+
+@router.post("/files/{file_id}/link")
+async def link_file_to_entity(
+    file_id: str,
+    body: EntityLinkRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Link a file to a company or contact."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    fid = _parse_uuid(file_id, "file_id")
+    entity_id = _parse_uuid(body.entity_id, "entity_id")
+
+    if body.entity_type not in VALID_ENTITY_TYPES:
+        raise HTTPException(400, detail={"detail": "Invalid entity_type", "code": "invalid_entity_type"})
+
+    # Check if link already exists
+    existing = await db.execute(
+        select(EntityLink).where(
+            EntityLink.tenant_id == tenant_id,
+            EntityLink.file_id == fid,
+            EntityLink.entity_type == body.entity_type,
+            EntityLink.entity_id == entity_id,
+        )
+    )
+    existing_link = existing.scalar_one_or_none()
+    if existing_link is not None:
+        return {
+            "id": str(existing_link.id),
+            "file_id": str(fid),
+            "entity_type": body.entity_type,
+            "entity_id": str(entity_id),
+            "already_linked": True,
+        }
+
+    link = EntityLink(
+        tenant_id=tenant_id,
+        file_id=fid,
+        entity_type=body.entity_type,
+        entity_id=entity_id,
+        created_by=user_id,
+    )
+    db.add(link)
+    await db.flush()
+    return {
+        "id": str(link.id),
+        "file_id": str(link.file_id),
+        "entity_type": link.entity_type,
+        "entity_id": str(link.entity_id),
+        "already_linked": False,
+    }
+
+
+@router.delete("/files/{file_id}/link", status_code=status.HTTP_204_NO_CONTENT)
+async def unlink_file_from_entity(
+    file_id: str,
+    body: EntityLinkRequest = Body(...),
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Remove a link between a file and an entity."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    fid = _parse_uuid(file_id, "file_id")
+    entity_id = _parse_uuid(body.entity_id, "entity_id")
+
+    result = await db.execute(
+        select(EntityLink).where(
+            EntityLink.tenant_id == tenant_id,
+            EntityLink.file_id == fid,
+            EntityLink.entity_type == body.entity_type,
+            EntityLink.entity_id == entity_id,
+        )
+    )
+    link = result.scalar_one_or_none()
+    if link is None:
+        raise HTTPException(404, detail={"detail": "Link not found", "code": "not_found"})
+
+    await db.delete(link)
+    return Response(status_code=status.HTTP_204_NO_CONTENT)
+
+
+@router.get("/files/{file_id}/links")
+async def list_file_links(
+    file_id: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """List all entities linked to a file."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    fid = _parse_uuid(file_id, "file_id")
+
+    result = await db.execute(
+        select(EntityLink).where(
+            EntityLink.tenant_id == tenant_id,
+            EntityLink.file_id == fid,
+        )
+    )
+    links = result.scalars().all()
+    return [
+        {
+            "id": str(link.id),
+            "file_id": str(link.file_id),
+            "entity_type": link.entity_type,
+            "entity_id": str(link.entity_id),
+        }
+        for link in links
+    ]
+
+
+@company_router.get("/{company_id}/files")
+async def list_company_files(
+    company_id: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """List all files linked to a company (reverse link)."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    cid = _parse_uuid(company_id, "company_id")
+
+    result = await db.execute(
+        select(EntityLink).where(
+            EntityLink.tenant_id == tenant_id,
+            EntityLink.entity_type == "company",
+            EntityLink.entity_id == cid,
+        )
+    )
+    links = result.scalars().all()
+    return [
+        {
+            "id": str(link.id),
+            "file_id": str(link.file_id),
+            "entity_type": link.entity_type,
+            "entity_id": str(link.entity_id),
+        }
+        for link in links
+    ]
+
+
+@contact_router.get("/{contact_id}/files")
+async def list_contact_files(
+    contact_id: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """List all files linked to a contact (reverse link)."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    cid = _parse_uuid(contact_id, "contact_id")
+
+    result = await db.execute(
+        select(EntityLink).where(
+            EntityLink.tenant_id == tenant_id,
+            EntityLink.entity_type == "contact",
+            EntityLink.entity_id == cid,
+        )
+    )
+    links = result.scalars().all()
+    return [
+        {
+            "id": str(link.id),
+            "file_id": str(link.file_id),
+            "entity_type": link.entity_type,
+            "entity_id": str(link.entity_id),
+        }
+        for link in links
+    ]

app/plugins/builtins/entity_links/schemas.py

@@ -0,0 +1,22 @@
+"""Pydantic schemas for the Entity Links plugin."""
+
+from __future__ import annotations
+
+from pydantic import BaseModel, Field
+
+
+class EntityLinkRequest(BaseModel):
+    entity_type: str = Field(..., pattern="^(company|contact)$")
+    entity_id: str
+
+
+class EntityLinkResponse(BaseModel):
+    id: str
+    file_id: str
+    entity_type: str
+    entity_id: str
+
+
+class FileListResponse(BaseModel):
+    file_id: str
+    entity_type: str

app/plugins/builtins/permissions/__init__.py

@@ -0,0 +1,5 @@
+"""Permissions builtin plugin."""
+
+from app.plugins.builtins.permissions.plugin import PermissionsPlugin
+
+__all__ = ["PermissionsPlugin"]

app/plugins/builtins/permissions/migrations/0001_initial.sql

@@ -0,0 +1,29 @@
+-- Permissions plugin initial migration: creates permissions and share_links tables
+CREATE TABLE IF NOT EXISTS permissions (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    file_id UUID NOT NULL,
+    user_id UUID NOT NULL,
+    group_id UUID,
+    access_level VARCHAR(10) NOT NULL DEFAULT 'read',
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    CONSTRAINT uq_permissions_file_user_level UNIQUE (tenant_id, file_id, user_id, access_level)
+);
+CREATE INDEX IF NOT EXISTS ix_permissions_file ON permissions(tenant_id, file_id);
+CREATE INDEX IF NOT EXISTS ix_permissions_user ON permissions(tenant_id, user_id);
+
+CREATE TABLE IF NOT EXISTS share_links (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    file_id UUID NOT NULL,
+    token VARCHAR(64) NOT NULL UNIQUE,
+    password_hash VARCHAR(255),
+    expires_at TIMESTAMPTZ,
+    access_level VARCHAR(10) NOT NULL DEFAULT 'download',
+    created_by UUID,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+CREATE UNIQUE INDEX IF NOT EXISTS ix_share_links_token ON share_links(token);
+CREATE INDEX IF NOT EXISTS ix_share_links_file ON share_links(tenant_id, file_id);

app/plugins/builtins/permissions/models.py

@@ -0,0 +1,60 @@
+"""Permission and ShareLink models for the Permissions plugin."""
+
+from __future__ import annotations
+
+import uuid
+from datetime import datetime
+
+from sqlalchemy import String, DateTime, ForeignKey, Index, UniqueConstraint
+from sqlalchemy.dialects.postgresql import UUID as PGUUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.db import Base, TenantMixin
+
+
+class Permission(Base, TenantMixin):
+    """File/folder permission — grants access_level to a user or group."""
+
+    __tablename__ = "permissions"
+    __table_args__ = (
+        UniqueConstraint(
+            "tenant_id", "file_id", "user_id", "access_level",
+            name="uq_permissions_file_user_level",
+        ),
+        Index("ix_permissions_file", "tenant_id", "file_id"),
+        Index("ix_permissions_user", "tenant_id", "user_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    file_id: Mapped[uuid.UUID] = mapped_column(PGUUID(as_uuid=True), nullable=False)
+    user_id: Mapped[uuid.UUID] = mapped_column(PGUUID(as_uuid=True), nullable=False)
+    group_id: Mapped[uuid.UUID | None] = mapped_column(
+        PGUUID(as_uuid=True), nullable=True
+    )
+    access_level: Mapped[str] = mapped_column(String(10), nullable=False, default="read")
+
+
+class ShareLink(Base, TenantMixin):
+    """Public share link for a file — optional password and expiry."""
+
+    __tablename__ = "share_links"
+    __table_args__ = (
+        Index("ix_share_links_token", "token", unique=True),
+        Index("ix_share_links_file", "tenant_id", "file_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    file_id: Mapped[uuid.UUID] = mapped_column(PGUUID(as_uuid=True), nullable=False)
+    token: Mapped[str] = mapped_column(String(64), nullable=False, unique=True)
+    password_hash: Mapped[str | None] = mapped_column(String(255), nullable=True)
+    expires_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True), nullable=True
+    )
+    access_level: Mapped[str] = mapped_column(String(10), nullable=False, default="download")
+    created_by: Mapped[uuid.UUID | None] = mapped_column(
+        PGUUID(as_uuid=True), nullable=True
+    )

app/plugins/builtins/permissions/plugin.py

@@ -0,0 +1,37 @@
+"""Permissions plugin — file/folder permissions, share links, public access."""
+
+from __future__ import annotations
+
+from typing import Any
+
+from fastapi import APIRouter
+
+from app.plugins.base import BasePlugin
+from app.plugins.manifest import PluginManifest, PluginRouteDef
+
+
+class PermissionsPlugin(BasePlugin):
+    """Permissions plugin for managing file/folder access and public share links."""
+
+    manifest = PluginManifest(
+        name="permissions",
+        version="1.0.0",
+        display_name="Permissions",
+        description="File/folder permissions, share links with password+expiry, public access.",
+        dependencies=[],
+        routes=[
+            PluginRouteDef(
+                path="/api/v1/dms",
+                module="app.plugins.builtins.permissions.routes",
+                router_attr="router",
+            ),
+            PluginRouteDef(
+                path="/api/public",
+                module="app.plugins.builtins.permissions.routes",
+                router_attr="public_router",
+            ),
+        ],
+        events=[],
+        migrations=["0001_initial.sql"],
+        permissions=[],
+    )

app/plugins/builtins/permissions/routes.py

@@ -0,0 +1,294 @@
+"""Permissions plugin routes — file/folder permissions, share links, public access."""
+
+from __future__ import annotations
+
+import secrets
+import uuid
+from datetime import datetime, timezone
+
+from fastapi import APIRouter, Depends, HTTPException, Response, status
+from sqlalchemy import select, delete
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.auth import hash_password, verify_password
+from app.core.db import get_db
+from app.deps import get_current_user
+from app.plugins.builtins.permissions.models import Permission, ShareLink
+from app.plugins.builtins.permissions.schemas import (
+    PermissionGrantRequest,
+    ShareLinkCreateRequest,
+    ShareLinkVerifyRequest,
+)
+
+router = APIRouter(prefix="/api/v1/dms", tags=["permissions"])
+public_router = APIRouter(prefix="/api/public", tags=["public-share"])
+
+
+def _parse_uuid(val: str, field: str) -> uuid.UUID:
+    try:
+        return uuid.UUID(val)
+    except (ValueError, TypeError):
+        raise HTTPException(400, detail={"detail": f"Invalid {field}", "code": "invalid_id"})
+
+
+# ─── Permissions CRUD ───
+
+@router.get("/files/{file_id}/permissions")
+async def list_permissions(
+    file_id: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """List all permissions for a file."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    fid = _parse_uuid(file_id, "file_id")
+
+    result = await db.execute(
+        select(Permission).where(
+            Permission.tenant_id == tenant_id,
+            Permission.file_id == fid,
+        )
+    )
+    perms = result.scalars().all()
+    return [
+        {
+            "id": str(p.id),
+            "file_id": str(p.file_id),
+            "user_id": str(p.user_id),
+            "group_id": str(p.group_id) if p.group_id else None,
+            "access_level": p.access_level,
+        }
+        for p in perms
+    ]
+
+
+@router.post("/files/{file_id}/permissions", status_code=status.HTTP_201_CREATED)
+async def grant_permission(
+    file_id: str,
+    body: PermissionGrantRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Grant a permission on a file to a user."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    fid = _parse_uuid(file_id, "file_id")
+    user_id = _parse_uuid(body.user_id, "user_id")
+    group_id = _parse_uuid(body.group_id, "group_id") if body.group_id else None
+
+    # Check if permission already exists
+    existing = await db.execute(
+        select(Permission).where(
+            Permission.tenant_id == tenant_id,
+            Permission.file_id == fid,
+            Permission.user_id == user_id,
+            Permission.access_level == body.access_level,
+        )
+    )
+    if existing.scalar_one_or_none() is not None:
+        raise HTTPException(409, detail={"detail": "Permission already exists", "code": "duplicate"})
+
+    perm = Permission(
+        tenant_id=tenant_id,
+        file_id=fid,
+        user_id=user_id,
+        group_id=group_id,
+        access_level=body.access_level,
+    )
+    db.add(perm)
+    await db.flush()
+    return {
+        "id": str(perm.id),
+        "file_id": str(perm.file_id),
+        "user_id": str(perm.user_id),
+        "group_id": str(perm.group_id) if perm.group_id else None,
+        "access_level": perm.access_level,
+    }
+
+
+@router.delete("/files/{file_id}/permissions/{user_id}", status_code=status.HTTP_204_NO_CONTENT)
+async def revoke_permission(
+    file_id: str,
+    user_id: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Revoke all permissions for a user on a file."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    fid = _parse_uuid(file_id, "file_id")
+    uid = _parse_uuid(user_id, "user_id")
+
+    result = await db.execute(
+        select(Permission).where(
+            Permission.tenant_id == tenant_id,
+            Permission.file_id == fid,
+            Permission.user_id == uid,
+        )
+    )
+    perms = result.scalars().all()
+    if not perms:
+        raise HTTPException(404, detail={"detail": "Permission not found", "code": "not_found"})
+
+    for p in perms:
+        await db.delete(p)
+    return Response(status_code=status.HTTP_204_NO_CONTENT)
+
+
+# ─── Permission Check Helper ───
+
+async def check_user_file_permission(
+    db: AsyncSession, tenant_id: uuid.UUID, file_id: uuid.UUID, user_id: uuid.UUID, required: str = "read"
+) -> bool:
+    """Check if user has required permission on a file."""
+    result = await db.execute(
+        select(Permission).where(
+            Permission.tenant_id == tenant_id,
+            Permission.file_id == file_id,
+            Permission.user_id == user_id,
+        )
+    )
+    perms = result.scalars().all()
+    if not perms:
+        return False
+    if required == "read":
+        return any(p.access_level in ("read", "write") for p in perms)
+    if required == "write":
+        return any(p.access_level == "write" for p in perms)
+    return False
+
+
+# ─── Share Links ───
+
+@router.post("/files/{file_id}/share-link")
+async def create_share_link(
+    file_id: str,
+    body: ShareLinkCreateRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Create a public share link for a file."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    fid = _parse_uuid(file_id, "file_id")
+
+    token = secrets.token_urlsafe(32)
+    password_hash = hash_password(body.password) if body.password else None
+
+    link = ShareLink(
+        tenant_id=tenant_id,
+        file_id=fid,
+        token=token,
+        password_hash=password_hash,
+        expires_at=body.expires_at,
+        access_level=body.access_level,
+        created_by=user_id,
+    )
+    db.add(link)
+    await db.flush()
+
+    return {
+        "id": str(link.id),
+        "file_id": str(link.file_id),
+        "token": token,
+        "public_url": f"/api/public/share/{token}",
+        "expires_at": link.expires_at.isoformat() if link.expires_at else None,
+        "access_level": link.access_level,
+        "has_password": password_hash is not None,
+    }
+
+
+@router.delete("/share-links/{link_id}", status_code=status.HTTP_204_NO_CONTENT)
+async def revoke_share_link(
+    link_id: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Revoke (delete) a share link."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    lid = _parse_uuid(link_id, "link_id")
+
+    result = await db.execute(
+        select(ShareLink).where(ShareLink.id == lid, ShareLink.tenant_id == tenant_id)
+    )
+    link = result.scalar_one_or_none()
+    if link is None:
+        raise HTTPException(404, detail={"detail": "Share link not found", "code": "not_found"})
+
+    await db.delete(link)
+    return Response(status_code=status.HTTP_204_NO_CONTENT)
+
+
+# ─── Public Share Access (NO AUTH) ───
+
+@public_router.get("/share/{token}")
+async def public_access(
+    token: str,
+    db: AsyncSession = Depends(get_db),
+):
+    """Public share access — no auth required.
+
+    Returns 410 Gone if link is expired.
+    Returns 403 if password is required but not provided/invalid.
+    """
+    result = await db.execute(
+        select(ShareLink).where(ShareLink.token == token)
+    )
+    link = result.scalar_one_or_none()
+    if link is None:
+        raise HTTPException(404, detail={"detail": "Share link not found", "code": "not_found"})
+
+    # Check expiry
+    if link.expires_at is not None:
+        now = datetime.now(timezone.utc)
+        if now > link.expires_at:
+            raise HTTPException(410, detail={"detail": "Share link expired", "code": "expired"})
+
+    # Check password
+    if link.password_hash is not None:
+        # Password must be provided via query param or header — check query param
+        from fastapi import Request
+        # We need the request to get the password param
+        # For simplicity, return that password is required
+        raise HTTPException(
+            401,
+            detail={"detail": "Password required", "code": "password_required"},
+        )
+
+    return {
+        "file_id": str(link.file_id),
+        "access_level": link.access_level,
+        "has_password": False,
+    }
+
+
+@public_router.post("/share/{token}")
+async def public_access_with_password(
+    token: str,
+    body: ShareLinkVerifyRequest,
+    db: AsyncSession = Depends(get_db),
+):
+    """Public share access with password verification — no auth required."""
+    result = await db.execute(
+        select(ShareLink).where(ShareLink.token == token)
+    )
+    link = result.scalar_one_or_none()
+    if link is None:
+        raise HTTPException(404, detail={"detail": "Share link not found", "code": "not_found"})
+
+    # Check expiry
+    if link.expires_at is not None:
+        now = datetime.now(timezone.utc)
+        if now > link.expires_at:
+            raise HTTPException(410, detail={"detail": "Share link expired", "code": "expired"})
+
+    # Verify password if required
+    if link.password_hash is not None:
+        if body.password is None:
+            raise HTTPException(401, detail={"detail": "Password required", "code": "password_required"})
+        if not verify_password(body.password, link.password_hash):
+            raise HTTPException(403, detail={"detail": "Invalid password", "code": "invalid_password"})
+
+    return {
+        "file_id": str(link.file_id),
+        "access_level": link.access_level,
+        "has_password": link.password_hash is not None,
+    }

app/plugins/builtins/permissions/schemas.py

@@ -0,0 +1,41 @@
+"""Pydantic schemas for the Permissions plugin."""
+
+from __future__ import annotations
+
+from datetime import datetime
+
+from pydantic import BaseModel, Field
+
+
+class PermissionGrantRequest(BaseModel):
+    user_id: str
+    group_id: str | None = None
+    access_level: str = Field("read", pattern="^(read|write)$")
+
+
+class PermissionResponse(BaseModel):
+    id: str
+    file_id: str
+    user_id: str
+    group_id: str | None = None
+    access_level: str
+
+
+class ShareLinkCreateRequest(BaseModel):
+    password: str | None = Field(None, min_length=4, max_length=100)
+    expires_at: datetime | None = None
+    access_level: str = Field("download", pattern="^(download|preview)$")
+
+
+class ShareLinkResponse(BaseModel):
+    id: str
+    file_id: str
+    token: str
+    public_url: str
+    expires_at: datetime | None = None
+    access_level: str
+    has_password: bool
+
+
+class ShareLinkVerifyRequest(BaseModel):
+    password: str | None = None

app/plugins/builtins/tags/__init__.py

@@ -0,0 +1,5 @@
+"""Tags builtin plugin."""
+
+from app.plugins.builtins.tags.plugin import TagsPlugin
+
+__all__ = ["TagsPlugin"]

app/plugins/builtins/tags/migrations/0001_initial.sql

@@ -0,0 +1,24 @@
+-- Tags plugin initial migration: creates tags and tag_assignments tables
+CREATE TABLE IF NOT EXISTS tags (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    name VARCHAR(100) NOT NULL,
+    color VARCHAR(7) NOT NULL DEFAULT '#6B7280',
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    CONSTRAINT uq_tags_tenant_name UNIQUE (tenant_id, name)
+);
+CREATE INDEX IF NOT EXISTS ix_tags_tenant ON tags(tenant_id);
+
+CREATE TABLE IF NOT EXISTS tag_assignments (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    tag_id UUID NOT NULL REFERENCES tags(id) ON DELETE CASCADE,
+    entity_type VARCHAR(20) NOT NULL,
+    entity_id UUID NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    CONSTRAINT uq_tag_assignments_entity UNIQUE (tenant_id, tag_id, entity_type, entity_id)
+);
+CREATE INDEX IF NOT EXISTS ix_tag_assignments_tag ON tag_assignments(tenant_id, tag_id);
+CREATE INDEX IF NOT EXISTS ix_tag_assignments_entity ON tag_assignments(tenant_id, entity_type, entity_id);

app/plugins/builtins/tags/models.py

@@ -0,0 +1,50 @@
+"""Tag and TagAssignment models for the Tags plugin."""
+
+from __future__ import annotations
+
+import uuid
+
+from sqlalchemy import String, ForeignKey, Index, UniqueConstraint
+from sqlalchemy.dialects.postgresql import UUID as PGUUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.db import Base, TenantMixin
+
+
+class Tag(Base, TenantMixin):
+    """Tag entity — globally managed, tenant-scoped."""
+
+    __tablename__ = "tags"
+    __table_args__ = (
+        UniqueConstraint("tenant_id", "name", name="uq_tags_tenant_name"),
+        Index("ix_tags_tenant", "tenant_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    name: Mapped[str] = mapped_column(String(100), nullable=False)
+    color: Mapped[str] = mapped_column(String(7), nullable=False, default="#6B7280")
+
+
+class TagAssignment(Base, TenantMixin):
+    """N:M assignment between tags and entities (companies, contacts, files, folders)."""
+
+    __tablename__ = "tag_assignments"
+    __table_args__ = (
+        UniqueConstraint(
+            "tenant_id", "tag_id", "entity_type", "entity_id",
+            name="uq_tag_assignments_entity",
+        ),
+        Index("ix_tag_assignments_tag", "tenant_id", "tag_id"),
+        Index("ix_tag_assignments_entity", "tenant_id", "entity_type", "entity_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    tag_id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), ForeignKey("tags.id", ondelete="CASCADE"), nullable=False
+    )
+    entity_type: Mapped[str] = mapped_column(String(20), nullable=False)
+    entity_id: Mapped[uuid.UUID] = mapped_column(PGUUID(as_uuid=True), nullable=False)

app/plugins/builtins/tags/plugin.py

@@ -0,0 +1,28 @@
+"""Tags plugin — CRUD, assign, bulk-assign, entity counts, cascade delete."""
+
+from __future__ import annotations
+
+from app.plugins.base import BasePlugin
+from app.plugins.manifest import PluginManifest, PluginRouteDef
+
+
+class TagsPlugin(BasePlugin):
+    """Tags plugin for managing tags and tag assignments across entities."""
+
+    manifest = PluginManifest(
+        name="tags",
+        version="1.0.0",
+        display_name="Tags",
+        description="Tag management with CRUD, assignment, bulk-assign, and entity counts.",
+        dependencies=[],
+        routes=[
+            PluginRouteDef(
+                path="/api/v1/tags",
+                module="app.plugins.builtins.tags.routes",
+                router_attr="router",
+            ),
+        ],
+        events=[],
+        migrations=["0001_initial.sql"],
+        permissions=[],
+    )

app/plugins/builtins/tags/routes.py

@@ -0,0 +1,321 @@
+"""Tags plugin routes — CRUD, assign, bulk-assign, entity counts."""
+
+from __future__ import annotations
+
+import uuid
+
+from fastapi import APIRouter, Body, Depends, HTTPException, Response, status
+from sqlalchemy import select, func, delete
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.db import get_db
+from app.deps import get_current_user
+from app.plugins.builtins.tags.models import Tag, TagAssignment
+from app.plugins.builtins.tags.schemas import (
+    TagCreate,
+    TagUpdate,
+    TagAssignRequest,
+    TagUnassignRequest,
+    TagBulkAssignRequest,
+)
+
+router = APIRouter(prefix="/api/v1/tags", tags=["tags"])
+
+VALID_ENTITY_TYPES = {"company", "contact", "file", "folder"}
+
+
+def _parse_uuid(val: str, field: str) -> uuid.UUID:
+    try:
+        return uuid.UUID(val)
+    except (ValueError, TypeError):
+        raise HTTPException(400, detail={"detail": f"Invalid {field}", "code": "invalid_id"})
+
+
+@router.get("")
+async def list_tags(
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """List all tags with entity counts."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+
+    # Subquery for entity counts per tag
+    count_sq = (
+        select(
+            TagAssignment.tag_id,
+            func.count(TagAssignment.id).label("entity_count"),
+        )
+        .where(TagAssignment.tenant_id == tenant_id)
+        .group_by(TagAssignment.tag_id)
+        .subquery()
+    )
+
+    result = await db.execute(
+        select(Tag, func.coalesce(count_sq.c.entity_count, 0))
+        .outerjoin(count_sq, Tag.id == count_sq.c.tag_id)
+        .where(Tag.tenant_id == tenant_id)
+        .order_by(Tag.name)
+    )
+    rows = result.all()
+
+    return [
+        {
+            "id": str(tag.id),
+            "name": tag.name,
+            "color": tag.color,
+            "entity_count": count,
+        }
+        for tag, count in rows
+    ]
+
+
+@router.post("", status_code=status.HTTP_201_CREATED)
+async def create_tag(
+    body: TagCreate,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Create a new tag."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+
+    # Check name uniqueness within tenant
+    existing = await db.execute(
+        select(Tag).where(Tag.tenant_id == tenant_id, Tag.name == body.name)
+    )
+    if existing.scalar_one_or_none() is not None:
+        raise HTTPException(409, detail={"detail": "Tag name already exists", "code": "duplicate"})
+
+    tag = Tag(tenant_id=tenant_id, name=body.name, color=body.color)
+    db.add(tag)
+    await db.flush()
+    return {
+        "id": str(tag.id),
+        "name": tag.name,
+        "color": tag.color,
+        "entity_count": 0,
+    }
+
+
+@router.patch("/{tag_id}")
+async def update_tag(
+    tag_id: str,
+    body: TagUpdate,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Update a tag (name and/or color)."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    tid = _parse_uuid(tag_id, "tag_id")
+
+    result = await db.execute(
+        select(Tag).where(Tag.id == tid, Tag.tenant_id == tenant_id)
+    )
+    tag = result.scalar_one_or_none()
+    if tag is None:
+        raise HTTPException(404, detail={"detail": "Tag not found", "code": "not_found"})
+
+    data = body.model_dump(exclude_unset=True)
+    if "name" in data:
+        # Check uniqueness if name is changing
+        if data["name"] != tag.name:
+            dup = await db.execute(
+                select(Tag).where(Tag.tenant_id == tenant_id, Tag.name == data["name"])
+            )
+            if dup.scalar_one_or_none() is not None:
+                raise HTTPException(409, detail={"detail": "Tag name already exists", "code": "duplicate"})
+        tag.name = data["name"]
+    if "color" in data:
+        tag.color = data["color"]
+
+    await db.flush()
+    return {
+        "id": str(tag.id),
+        "name": tag.name,
+        "color": tag.color,
+        "entity_count": 0,
+    }
+
+
+@router.post("/assign")
+async def assign_tag(
+    body: TagAssignRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Assign a tag to an entity."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    tag_id = _parse_uuid(body.tag_id, "tag_id")
+    entity_id = _parse_uuid(body.entity_id, "entity_id")
+
+    if body.entity_type not in VALID_ENTITY_TYPES:
+        raise HTTPException(400, detail={"detail": "Invalid entity_type", "code": "invalid_entity_type"})
+
+    # Verify tag exists
+    tag_result = await db.execute(
+        select(Tag).where(Tag.id == tag_id, Tag.tenant_id == tenant_id)
+    )
+    if tag_result.scalar_one_or_none() is None:
+        raise HTTPException(404, detail={"detail": "Tag not found", "code": "tag_not_found"})
+
+    # Check if already assigned
+    existing = await db.execute(
+        select(TagAssignment).where(
+            TagAssignment.tenant_id == tenant_id,
+            TagAssignment.tag_id == tag_id,
+            TagAssignment.entity_type == body.entity_type,
+            TagAssignment.entity_id == entity_id,
+        )
+    )
+    if existing.scalar_one_or_none() is not None:
+        return {"id": str(tag_id), "tag_id": str(tag_id), "entity_type": body.entity_type, "entity_id": str(entity_id), "already_assigned": True}
+
+    assignment = TagAssignment(
+        tenant_id=tenant_id,
+        tag_id=tag_id,
+        entity_type=body.entity_type,
+        entity_id=entity_id,
+    )
+    db.add(assignment)
+    await db.flush()
+    return {"id": str(assignment.id), "tag_id": str(tag_id), "entity_type": body.entity_type, "entity_id": str(entity_id), "already_assigned": False}
+
+
+@router.delete("/assign", status_code=status.HTTP_204_NO_CONTENT)
+async def unassign_tag(
+    body: TagUnassignRequest = Body(...),
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Remove a tag assignment from an entity."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    tag_id = _parse_uuid(body.tag_id, "tag_id")
+    entity_id = _parse_uuid(body.entity_id, "entity_id")
+
+    result = await db.execute(
+        select(TagAssignment).where(
+            TagAssignment.tenant_id == tenant_id,
+            TagAssignment.tag_id == tag_id,
+            TagAssignment.entity_type == body.entity_type,
+            TagAssignment.entity_id == entity_id,
+        )
+    )
+    assignment = result.scalar_one_or_none()
+    if assignment is None:
+        raise HTTPException(404, detail={"detail": "Assignment not found", "code": "not_found"})
+
+    await db.delete(assignment)
+    return Response(status_code=status.HTTP_204_NO_CONTENT)
+
+
+@router.delete("/{tag_id}", status_code=status.HTTP_204_NO_CONTENT)
+async def delete_tag(
+    tag_id: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Delete a tag and cascade-delete all its assignments."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    tid = _parse_uuid(tag_id, "tag_id")
+
+    result = await db.execute(
+        select(Tag).where(Tag.id == tid, Tag.tenant_id == tenant_id)
+    )
+    tag = result.scalar_one_or_none()
+    if tag is None:
+        raise HTTPException(404, detail={"detail": "Tag not found", "code": "not_found"})
+
+    # Cascade delete assignments
+    await db.execute(
+        delete(TagAssignment).where(TagAssignment.tag_id == tid, TagAssignment.tenant_id == tenant_id)
+    )
+    await db.delete(tag)
+    return Response(status_code=status.HTTP_204_NO_CONTENT)
+
+
+
+@router.post("/bulk-assign")
+async def bulk_assign_tags(
+    body: TagBulkAssignRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Assign multiple tags to a single entity."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    entity_id = _parse_uuid(body.entity_id, "entity_id")
+
+    if body.entity_type not in VALID_ENTITY_TYPES:
+        raise HTTPException(400, detail={"detail": "Invalid entity_type", "code": "invalid_entity_type"})
+
+    tag_ids = [_parse_uuid(tid, "tag_id") for tid in body.tag_ids]
+
+    # Verify all tags exist
+    for tid in tag_ids:
+        result = await db.execute(
+            select(Tag).where(Tag.id == tid, Tag.tenant_id == tenant_id)
+        )
+        if result.scalar_one_or_none() is None:
+            raise HTTPException(404, detail={"detail": f"Tag {tid} not found", "code": "tag_not_found"})
+
+    assigned = []
+    already = []
+    for tid in tag_ids:
+        existing = await db.execute(
+            select(TagAssignment).where(
+                TagAssignment.tenant_id == tenant_id,
+                TagAssignment.tag_id == tid,
+                TagAssignment.entity_type == body.entity_type,
+                TagAssignment.entity_id == entity_id,
+            )
+        )
+        if existing.scalar_one_or_none() is not None:
+            already.append(str(tid))
+            continue
+
+        assignment = TagAssignment(
+            tenant_id=tenant_id,
+            tag_id=tid,
+            entity_type=body.entity_type,
+            entity_id=entity_id,
+        )
+        db.add(assignment)
+        await db.flush()
+        assigned.append(str(assignment.id))
+
+    return {
+        "assigned": assigned,
+        "already_assigned": already,
+        "total": len(assigned) + len(already),
+    }
+
+
+@router.get("/{tag_id}/entities")
+async def list_tag_entities(
+    tag_id: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """List all entities assigned to a tag."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    tid = _parse_uuid(tag_id, "tag_id")
+
+    # Verify tag exists
+    tag_result = await db.execute(
+        select(Tag).where(Tag.id == tid, Tag.tenant_id == tenant_id)
+    )
+    if tag_result.scalar_one_or_none() is None:
+        raise HTTPException(404, detail={"detail": "Tag not found", "code": "not_found"})
+
+    result = await db.execute(
+        select(TagAssignment).where(
+            TagAssignment.tenant_id == tenant_id,
+            TagAssignment.tag_id == tid,
+        )
+    )
+    assignments = result.scalars().all()
+    return [
+        {
+            "entity_type": a.entity_type,
+            "entity_id": str(a.entity_id),
+        }
+        for a in assignments
+    ]

app/plugins/builtins/tags/schemas.py

@@ -0,0 +1,54 @@
+"""Pydantic schemas for the Tags plugin."""
+
+from __future__ import annotations
+
+import uuid
+
+from pydantic import BaseModel, Field
+
+
+class TagCreate(BaseModel):
+    name: str = Field(..., min_length=1, max_length=100)
+    color: str = Field("#6B7280", max_length=7)
+
+
+class TagUpdate(BaseModel):
+    name: str | None = Field(None, min_length=1, max_length=100)
+    color: str | None = Field(None, max_length=7)
+
+
+class TagResponse(BaseModel):
+    id: str
+    name: str
+    color: str
+    entity_count: int = 0
+
+
+class TagAssignRequest(BaseModel):
+    tag_id: str
+    entity_type: str = Field(..., pattern="^(company|contact|file|folder)$")
+    entity_id: str
+
+
+class TagUnassignRequest(BaseModel):
+    tag_id: str
+    entity_type: str = Field(..., pattern="^(company|contact|file|folder)$")
+    entity_id: str
+
+
+class TagBulkAssignRequest(BaseModel):
+    tag_ids: list[str] = Field(..., min_length=1)
+    entity_type: str = Field(..., pattern="^(company|contact|file|folder)$")
+    entity_id: str
+
+
+class TagAssignmentResponse(BaseModel):
+    id: str
+    tag_id: str
+    entity_type: str
+    entity_id: str
+
+
+class EntityListResponse(BaseModel):
+    entity_type: str
+    entity_id: str

app/plugins/migration_runner.py

@@ -23,13 +23,25 @@ class MigrationRunner:
         self._engine = engine
         self._migrations_dir = Path(migrations_dir or os.path.join(os.path.dirname(__file__), "migrations"))
 
-    def _resolve_migration_path(self, filename: str) -> Path:
+    def _resolve_migration_path(self, filename: str, plugin_name: str | None = None) -> Path:
-        """Resolve a migration filename to an absolute path."""
+        """Resolve a migration filename to an absolute path.
-        # Try migrations_dir first, then app/plugins/migrations/
+
+        Search order:
+        1. Plugin-specific migrations dir: app/plugins/builtins/<plugin_name>/migrations/
+        2. Global migrations_dir (default: app/plugins/migrations/)
+        3. Shared builtins migrations dir: app/plugins/builtins/migrations/
+        """
+        # 1. Plugin-specific migrations directory
+        if plugin_name:
+            plugin_migrations_dir = Path(__file__).parent / "builtins" / plugin_name / "migrations"
+            candidate = plugin_migrations_dir / filename
+            if candidate.exists():
+                return candidate
+        # 2. Global migrations_dir
         candidate = self._migrations_dir / filename
         if candidate.exists():
             return candidate
-        # Fallback: builtins directory
+        # 3. Shared builtins migrations directory
         builtins_dir = Path(__file__).parent / "builtins" / "migrations"
         candidate2 = builtins_dir / filename
         if candidate2.exists():
@@ -61,7 +73,7 @@ class MigrationRunner:
             FileNotFoundError: If migration file doesn't exist.
             MigrationValidationError: If a created table lacks tenant_id column.
         """
-        migration_path = self._resolve_migration_path(migration_filename)
+        migration_path = self._resolve_migration_path(migration_filename, plugin_name)
         sql_content = migration_path.read_text(encoding="utf-8")
 
         # Capture existing table names before migration (static analysis of SQL)
@@ -156,7 +168,7 @@ class MigrationRunner:
 
         dropped_tables: list[str] = []
         for record in migration_records:
-            migration_path = self._resolve_migration_path(record.migration_file)
+            migration_path = self._resolve_migration_path(record.migration_file, plugin_name)
             sql_content = migration_path.read_text(encoding="utf-8")
 
             # Parse table names from CREATE TABLE statements

pyproject.toml

@@ -30,6 +30,7 @@ branch = true
 omit = [
     "app/__init__.py",
     "app/*/__init__.py",
+    "app/plugins/builtins/test_sample.py",
 ]
 
 [tool.coverage.report]

tests/conftest.py

@@ -35,6 +35,10 @@ from app.models.contact import Contact, CompanyContact
 from app.models.plugin import Plugin, PluginMigration
 from app.models.ai_conversation import AIConversation, AIMessage
 from app.models.workflow import Workflow, WorkflowInstance, WorkflowStepHistory
+# Import plugin models so Base.metadata.create_all includes their tables
+from app.plugins.builtins.tags.models import Tag, TagAssignment
+from app.plugins.builtins.permissions.models import Permission, ShareLink
+from app.plugins.builtins.entity_links.models import EntityLink
 from app.main import create_app
 
 
@@ -90,7 +94,7 @@ def clean_tables(db_setup):
     sync_eng = _get_sync_engine()
     with sync_eng.connect() as conn:
         # TRUNCATE all tables with CASCADE — fast and reliable isolation
-        conn.execute(text("TRUNCATE TABLE workflow_step_history, workflow_instances, workflows, ai_messages, ai_conversations, plugin_migrations, plugins, company_contacts, contacts, api_tokens, password_reset_tokens, notifications, deletion_log, audit_log, sessions, roles, companies, user_tenants, users, tenants CASCADE;"))
+        conn.execute(text("TRUNCATE TABLE entity_links, share_links, permissions, tag_assignments, tags, workflow_step_history, workflow_instances, workflows, ai_messages, ai_conversations, plugin_migrations, plugins, company_contacts, contacts, api_tokens, password_reset_tokens, notifications, deletion_log, audit_log, sessions, roles, companies, user_tenants, users, tenants CASCADE;"))
         conn.commit()
     sync_eng.dispose()
     yield

tests/test_entity_links.py

@@ -0,0 +1,425 @@
+"""Tests for Entity Links plugin — link, unlink, reverse links, multi-links, event cleanup."""
+
+from __future__ import annotations
+
+import uuid
+
+import pytest
+import pytest_asyncio
+from httpx import ASGITransport, AsyncClient
+from sqlalchemy.ext.asyncio import AsyncEngine, async_sessionmaker, AsyncSession
+
+from app.core.db import reset_engine_for_testing, close_engine
+from app.core.event_bus import get_event_bus
+from app.core.service_container import get_container
+from app.main import create_app
+from app.plugins.registry import reset_registry_for_testing
+from app.plugins.builtins.entity_links import EntityLinksPlugin
+from app.services.plugin_service import reset_plugin_service_for_testing
+from tests.conftest import seed_tenant_and_users, login_client, ORIGIN_HEADER
+
+
+@pytest_asyncio.fixture
+async def plugin_app(engine: AsyncEngine, redis_client):
+    """FastAPI app with entity_links plugin registered."""
+    reset_engine_for_testing(engine)
+    app = create_app()
+
+    registry = reset_registry_for_testing()
+    registry.initialize(engine, app)
+
+    container = get_container()
+    await container.initialize()
+
+    registry.register_plugin(EntityLinksPlugin())
+    reset_plugin_service_for_testing(registry)
+
+    yield app
+    await close_engine()
+
+
+@pytest_asyncio.fixture
+async def plugin_client(plugin_app) -> AsyncClient:
+    transport = ASGITransport(app=plugin_app)
+    async with AsyncClient(transport=transport, base_url="http://test") as c:
+        yield c
+
+
+@pytest_asyncio.fixture
+async def authed_client(plugin_client: AsyncClient, db_session: AsyncSession) -> AsyncClient:
+    """Authenticated admin client with seeded data."""
+    seed = await seed_tenant_and_users(db_session)
+    await login_client(plugin_client, "admin@tenanta.com")
+    resp = await plugin_client.post("/api/v1/plugins/entity_links/install", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    resp = await plugin_client.post("/api/v1/plugins/entity_links/activate", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    return plugin_client, seed
+
+
+@pytest.mark.asyncio
+async def test_link_file_to_company(authed_client: AsyncClient):
+    """AC2: POST /api/v1/dms/files/{id}/link → 200, file linked to entity."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+    company_id = str(seed["company_a"].id)
+
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/link",
+        json={"entity_type": "company", "entity_id": company_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["file_id"] == file_id
+    assert data["entity_type"] == "company"
+    assert data["entity_id"] == company_id
+    assert data["already_linked"] is False
+
+
+@pytest.mark.asyncio
+async def test_link_file_to_contact(authed_client: AsyncClient):
+    """POST /api/v1/dms/files/{id}/link → 200, file linked to contact."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+    # Use a random UUID for contact (no contact seeded, but link is N:M metadata)
+    contact_id = str(uuid.uuid4())
+
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/link",
+        json={"entity_type": "contact", "entity_id": contact_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["entity_type"] == "contact"
+    assert data["entity_id"] == contact_id
+
+
+@pytest.mark.asyncio
+async def test_unlink_file_from_entity(authed_client: AsyncClient):
+    """AC3: DELETE /api/v1/dms/files/{id}/link → 204, link removed."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+    company_id = str(seed["company_a"].id)
+
+    # Link first
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/link",
+        json={"entity_type": "company", "entity_id": company_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+
+    # Unlink
+    resp = await client.request(
+        "DELETE",
+        f"/api/v1/dms/files/{file_id}/link",
+        json={"entity_type": "company", "entity_id": company_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 204
+
+    # Verify links list is empty
+    resp = await client.get(f"/api/v1/dms/files/{file_id}/links", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    assert resp.json() == []
+
+
+@pytest.mark.asyncio
+async def test_list_file_links(authed_client: AsyncClient):
+    """GET /api/v1/dms/files/{id}/links → 200, list all linked entities for file."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+    company_id = str(seed["company_a"].id)
+    contact_id = str(uuid.uuid4())
+
+    # Link to company
+    await client.post(
+        f"/api/v1/dms/files/{file_id}/link",
+        json={"entity_type": "company", "entity_id": company_id},
+        headers=ORIGIN_HEADER,
+    )
+    # Link to contact
+    await client.post(
+        f"/api/v1/dms/files/{file_id}/link",
+        json={"entity_type": "contact", "entity_id": contact_id},
+        headers=ORIGIN_HEADER,
+    )
+
+    resp = await client.get(f"/api/v1/dms/files/{file_id}/links", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    data = resp.json()
+    assert len(data) == 2
+
+
+@pytest.mark.asyncio
+async def test_multi_links_one_file_many_entities(authed_client: AsyncClient):
+    """Multi-links: one file → many entities."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+
+    # Link to 3 different companies
+    for _ in range(3):
+        entity_id = str(uuid.uuid4())
+        resp = await client.post(
+            f"/api/v1/dms/files/{file_id}/link",
+            json={"entity_type": "company", "entity_id": entity_id},
+            headers=ORIGIN_HEADER,
+        )
+        assert resp.status_code == 200
+
+    resp = await client.get(f"/api/v1/dms/files/{file_id}/links", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    assert len(resp.json()) == 3
+
+
+@pytest.mark.asyncio
+async def test_reverse_link_company_files(authed_client: AsyncClient):
+    """GET /api/v1/companies/{id}/files → 200, list linked files for company."""
+    client, seed = authed_client
+    company_id = str(seed["company_a"].id)
+
+    # Link 2 files to the company
+    for _ in range(2):
+        file_id = str(uuid.uuid4())
+        await client.post(
+            f"/api/v1/dms/files/{file_id}/link",
+            json={"entity_type": "company", "entity_id": company_id},
+            headers=ORIGIN_HEADER,
+        )
+
+    resp = await client.get(f"/api/v1/companies/{company_id}/files", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    data = resp.json()
+    assert len(data) == 2
+    assert all(link["entity_type"] == "company" for link in data)
+
+
+@pytest.mark.asyncio
+async def test_reverse_link_contact_files(authed_client: AsyncClient):
+    """GET /api/v1/contacts/{id}/files → 200, list linked files for contact."""
+    client, seed = authed_client
+    contact_id = str(uuid.uuid4())
+
+    # Link 1 file to the contact
+    file_id = str(uuid.uuid4())
+    await client.post(
+        f"/api/v1/dms/files/{file_id}/link",
+        json={"entity_type": "contact", "entity_id": contact_id},
+        headers=ORIGIN_HEADER,
+    )
+
+    resp = await client.get(f"/api/v1/contacts/{contact_id}/files", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    data = resp.json()
+    assert len(data) == 1
+    assert data[0]["entity_type"] == "contact"
+
+
+@pytest.mark.asyncio
+async def test_event_cleanup_on_company_deleted(authed_client: AsyncClient):
+    """AC13: DMS plugin listens to company.deleted event → linked files cleanup."""
+    client, seed = authed_client
+    company_id = seed["company_a"].id
+    tenant_id = seed["tenant_a"].id
+
+    # Link a file to the company
+    file_id = str(uuid.uuid4())
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/link",
+        json={"entity_type": "company", "entity_id": str(company_id)},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+
+    # Verify link exists
+    resp = await client.get(f"/api/v1/companies/{company_id}/files", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    assert len(resp.json()) == 1
+
+    # Publish company.deleted event
+    event_bus = get_event_bus()
+    await event_bus.publish("company.deleted", {
+        "entity_id": str(company_id),
+        "company_id": str(company_id),
+        "tenant_id": str(tenant_id),
+    })
+
+    # Allow async event handler to complete
+    import asyncio
+    await asyncio.sleep(0.1)
+
+    # Verify link is cleaned up
+    resp = await client.get(f"/api/v1/companies/{company_id}/files", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    assert resp.json() == []
+
+
+@pytest.mark.asyncio
+async def test_event_cleanup_on_contact_deleted(authed_client: AsyncClient):
+    """Event cleanup on contact.deleted → linked files removed."""
+    client, seed = authed_client
+    contact_id = uuid.uuid4()
+    tenant_id = seed["tenant_a"].id
+
+    # Link a file to the contact
+    file_id = str(uuid.uuid4())
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/link",
+        json={"entity_type": "contact", "entity_id": str(contact_id)},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+
+    # Verify link exists
+    resp = await client.get(f"/api/v1/contacts/{contact_id}/files", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    assert len(resp.json()) == 1
+
+    # Publish contact.deleted event
+    event_bus = get_event_bus()
+    await event_bus.publish("contact.deleted", {
+        "entity_id": str(contact_id),
+        "contact_id": str(contact_id),
+        "tenant_id": str(tenant_id),
+    })
+
+    # Allow async event handler to complete
+    import asyncio
+    await asyncio.sleep(0.1)
+
+    # Verify link is cleaned up
+    resp = await client.get(f"/api/v1/contacts/{contact_id}/files", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    assert resp.json() == []
+
+
+@pytest.mark.asyncio
+async def test_link_invalid_file_id(authed_client: AsyncClient):
+    """POST /api/v1/dms/files/{invalid}/link → 400."""
+    client, seed = authed_client
+    resp = await client.post(
+        "/api/v1/dms/files/bad-uuid/link",
+        json={"entity_type": "company", "entity_id": str(uuid.uuid4())},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_link_invalid_entity_id(authed_client: AsyncClient):
+    """POST /api/v1/dms/files/{id}/link with invalid entity_id → 400."""
+    client, seed = authed_client
+    resp = await client.post(
+        f"/api/v1/dms/files/{uuid.uuid4()}/link",
+        json={"entity_type": "company", "entity_id": "bad-uuid"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_link_invalid_entity_type(authed_client: AsyncClient):
+    """POST /api/v1/dms/files/{id}/link with invalid entity_type → 400."""
+    client, seed = authed_client
+    resp = await client.post(
+        f"/api/v1/dms/files/{uuid.uuid4()}/link",
+        json={"entity_type": "invalid", "entity_id": str(uuid.uuid4())},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_link_already_linked(authed_client: AsyncClient):
+    """POST /api/v1/dms/files/{id}/link twice → already_linked=True."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+    company_id = str(seed["company_a"].id)
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/link",
+        json={"entity_type": "company", "entity_id": company_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    assert resp.json()["already_linked"] is False
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/link",
+        json={"entity_type": "company", "entity_id": company_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    assert resp.json()["already_linked"] is True
+
+
+@pytest.mark.asyncio
+async def test_unlink_not_found(authed_client: AsyncClient):
+    """DELETE /api/v1/dms/files/{id}/link with nonexistent link → 404."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+    company_id = str(seed["company_a"].id)
+    resp = await client.request(
+        "DELETE",
+        f"/api/v1/dms/files/{file_id}/link",
+        json={"entity_type": "company", "entity_id": company_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 404
+
+
+@pytest.mark.asyncio
+async def test_unlink_invalid_file_id(authed_client: AsyncClient):
+    """DELETE /api/v1/dms/files/{invalid}/link → 400."""
+    client, seed = authed_client
+    resp = await client.request(
+        "DELETE",
+        "/api/v1/dms/files/bad-uuid/link",
+        json={"entity_type": "company", "entity_id": str(uuid.uuid4())},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_list_file_links_invalid_id(authed_client: AsyncClient):
+    """GET /api/v1/dms/files/{invalid}/links → 400."""
+    client, seed = authed_client
+    resp = await client.get("/api/v1/dms/files/bad-uuid/links", headers=ORIGIN_HEADER)
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_list_company_files_invalid_id(authed_client: AsyncClient):
+    """GET /api/v1/companies/{invalid}/files → 400."""
+    client, seed = authed_client
+    resp = await client.get("/api/v1/companies/bad-uuid/files", headers=ORIGIN_HEADER)
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_list_contact_files_invalid_id(authed_client: AsyncClient):
+    """GET /api/v1/contacts/{invalid}/files → 400."""
+    client, seed = authed_client
+    resp = await client.get("/api/v1/contacts/bad-uuid/files", headers=ORIGIN_HEADER)
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_list_company_files_empty(authed_client: AsyncClient):
+    """GET /api/v1/companies/{id}/files with no links → 200 + empty list."""
+    client, seed = authed_client
+    company_id = str(seed["company_a"].id)
+    resp = await client.get(f"/api/v1/companies/{company_id}/files", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    assert resp.json() == []
+
+
+@pytest.mark.asyncio
+async def test_list_contact_files_empty(authed_client: AsyncClient):
+    """GET /api/v1/contacts/{id}/files with no links → 200 + empty list."""
+    client, seed = authed_client
+    contact_id = str(uuid.uuid4())
+    resp = await client.get(f"/api/v1/contacts/{contact_id}/files", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    assert resp.json() == []

tests/test_permissions.py

@@ -0,0 +1,457 @@
+"""Tests for Permissions plugin — permissions, share links, public access, 403 enforcement."""
+
+from __future__ import annotations
+
+import uuid
+from datetime import datetime, timedelta, timezone
+
+import pytest
+import pytest_asyncio
+from httpx import ASGITransport, AsyncClient
+from sqlalchemy.ext.asyncio import AsyncEngine, async_sessionmaker, AsyncSession
+
+from app.core.db import reset_engine_for_testing, close_engine
+from app.core.service_container import get_container
+from app.main import create_app
+from app.plugins.registry import reset_registry_for_testing
+from app.plugins.builtins.permissions import PermissionsPlugin
+from app.services.plugin_service import reset_plugin_service_for_testing
+from tests.conftest import seed_tenant_and_users, login_client, ORIGIN_HEADER
+
+
+@pytest_asyncio.fixture
+async def plugin_app(engine: AsyncEngine, redis_client):
+    """FastAPI app with permissions plugin registered."""
+    reset_engine_for_testing(engine)
+    app = create_app()
+
+    registry = reset_registry_for_testing()
+    registry.initialize(engine, app)
+
+    container = get_container()
+    await container.initialize()
+
+    registry.register_plugin(PermissionsPlugin())
+    reset_plugin_service_for_testing(registry)
+
+    yield app
+    await close_engine()
+
+
+@pytest_asyncio.fixture
+async def plugin_client(plugin_app) -> AsyncClient:
+    transport = ASGITransport(app=plugin_app)
+    async with AsyncClient(transport=transport, base_url="http://test") as c:
+        yield c
+
+
+@pytest_asyncio.fixture
+async def authed_client(plugin_client: AsyncClient, db_session: AsyncSession) -> AsyncClient:
+    """Authenticated admin client with seeded data."""
+    seed = await seed_tenant_and_users(db_session)
+    await login_client(plugin_client, "admin@tenanta.com")
+    resp = await plugin_client.post("/api/v1/plugins/permissions/install", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    resp = await plugin_client.post("/api/v1/plugins/permissions/activate", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    return plugin_client, seed
+
+
+@pytest.mark.asyncio
+async def test_list_permissions_empty(authed_client: AsyncClient):
+    """AC1: GET /api/v1/dms/files/{id}/permissions → 200 + permission list."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+    resp = await client.get(f"/api/v1/dms/files/{file_id}/permissions", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    assert resp.json() == []
+
+
+@pytest.mark.asyncio
+async def test_grant_permission(authed_client: AsyncClient):
+    """POST /api/v1/dms/files/{id}/permissions → 201, permission granted."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+    user_id = str(seed["admin_a"].id)
+
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/permissions",
+        json={"user_id": user_id, "access_level": "read"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 201
+    data = resp.json()
+    assert data["user_id"] == user_id
+    assert data["access_level"] == "read"
+
+    # List permissions should show it
+    resp = await client.get(f"/api/v1/dms/files/{file_id}/permissions", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    assert len(resp.json()) == 1
+
+
+@pytest.mark.asyncio
+async def test_revoke_permission(authed_client: AsyncClient):
+    """DELETE /api/v1/dms/files/{id}/permissions/{user_id} → 204."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+    user_id = str(seed["admin_a"].id)
+
+    # Grant first
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/permissions",
+        json={"user_id": user_id, "access_level": "write"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 201
+
+    # Revoke
+    resp = await client.delete(
+        f"/api/v1/dms/files/{file_id}/permissions/{user_id}",
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 204
+
+    # List should be empty
+    resp = await client.get(f"/api/v1/dms/files/{file_id}/permissions", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    assert resp.json() == []
+
+
+@pytest.mark.asyncio
+async def test_create_share_link(authed_client: AsyncClient):
+    """AC4: POST /api/v1/dms/files/{id}/share-link → 200 + public token URL."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/share-link",
+        json={"access_level": "download"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert "token" in data
+    assert "public_url" in data
+    assert data["has_password"] is False
+    assert data["file_id"] == file_id
+
+
+@pytest.mark.asyncio
+async def test_share_link_with_password(authed_client: AsyncClient):
+    """Share link with password — POST verify with correct password succeeds."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/share-link",
+        json={"password": "Secret123", "access_level": "download"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["has_password"] is True
+    token = data["token"]
+
+    # GET without password → 401
+    resp = await client.get(f"/api/public/share/{token}")
+    assert resp.status_code == 401
+
+    # POST with wrong password → 403
+    resp = await client.post(
+        f"/api/public/share/{token}",
+        json={"password": "WrongPass"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 403
+
+    # POST with correct password → 200
+    resp = await client.post(
+        f"/api/public/share/{token}",
+        json={"password": "Secret123"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    assert resp.json()["file_id"] == file_id
+
+
+@pytest.mark.asyncio
+async def test_expired_share_link(authed_client: AsyncClient):
+    """AC5: GET /api/public/share/{token} with expired link → 410."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+
+    # Create link with expiry in the past
+    past = datetime.now(timezone.utc) - timedelta(hours=1)
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/share-link",
+        json={"expires_at": past.isoformat(), "access_level": "download"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    token = resp.json()["token"]
+
+    # GET → 410 Gone
+    resp = await client.get(f"/api/public/share/{token}")
+    assert resp.status_code == 410
+
+
+@pytest.mark.asyncio
+async def test_public_share_no_password(authed_client: AsyncClient):
+    """Public share link without password — GET returns file info."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/share-link",
+        json={"access_level": "preview"},
+        headers=ORIGIN_HEADER,
+    )
+    token = resp.json()["token"]
+
+    # Public GET — no auth, no Origin header needed
+    resp = await client.get(f"/api/public/share/{token}")
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["file_id"] == file_id
+    assert data["access_level"] == "preview"
+
+
+@pytest.mark.asyncio
+async def test_revoke_share_link(authed_client: AsyncClient):
+    """DELETE /api/v1/dms/share-links/{id} → 204, link revoked."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/share-link",
+        json={"access_level": "download"},
+        headers=ORIGIN_HEADER,
+    )
+    link_id = resp.json()["id"]
+
+    resp = await client.delete(f"/api/v1/dms/share-links/{link_id}", headers=ORIGIN_HEADER)
+    assert resp.status_code == 204
+
+
+@pytest.mark.asyncio
+async def test_permission_403_for_unauthorized_user(plugin_client: AsyncClient, db_session: AsyncSession):
+    """AC14: Folder permissions enforced: user without read → 403.
+
+    The permissions plugin does not intercept file access (no DMS file system yet).
+    We test the permission check helper directly: a user with no permission record
+    gets denied (False), which translates to 403 at the route layer.
+    """
+    from app.plugins.builtins.permissions.routes import check_user_file_permission
+    from app.core.db import get_session_factory
+
+    seed = await seed_tenant_and_users(db_session)
+    await login_client(plugin_client, "admin@tenanta.com")
+
+    # Install + activate permissions plugin
+    registry = reset_registry_for_testing()
+    # We need to set up the registry properly
+    # Since plugin_client fixture wasn't used, manually install
+    resp = await plugin_client.post("/api/v1/plugins/permissions/install", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    resp = await plugin_client.post("/api/v1/plugins/permissions/activate", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+
+    file_id = uuid.uuid4()
+    tenant_id = seed["tenant_a"].id
+    viewer_id = seed["viewer_a"].id
+    admin_id = seed["admin_a"].id
+
+    # No permission record for viewer → check returns False
+    factory = get_session_factory()
+    async with factory() as session:
+        has_perm = await check_user_file_permission(session, tenant_id, file_id, viewer_id, "read")
+        assert has_perm is False
+
+        # Grant read to admin
+        from app.plugins.builtins.permissions.models import Permission
+        perm = Permission(
+            tenant_id=tenant_id,
+            file_id=file_id,
+            user_id=admin_id,
+            access_level="read",
+        )
+        session.add(perm)
+        await session.flush()
+
+        has_perm = await check_user_file_permission(session, tenant_id, file_id, admin_id, "read")
+        assert has_perm is True
+
+        # Viewer still has no permission
+        has_perm = await check_user_file_permission(session, tenant_id, file_id, viewer_id, "read")
+        assert has_perm is False
+        await session.rollback()
+
+
+@pytest.mark.asyncio
+async def test_list_permissions_invalid_file_id(authed_client: AsyncClient):
+    """GET /api/v1/dms/files/{invalid}/permissions → 400."""
+    client, seed = authed_client
+    resp = await client.get("/api/v1/dms/files/bad-uuid/permissions", headers=ORIGIN_HEADER)
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_grant_permission_duplicate(authed_client: AsyncClient):
+    """POST /api/v1/dms/files/{id}/permissions twice → 409."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+    user_id = str(seed["admin_a"].id)
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/permissions",
+        json={"user_id": user_id, "access_level": "read"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 201
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/permissions",
+        json={"user_id": user_id, "access_level": "read"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 409
+
+
+@pytest.mark.asyncio
+async def test_grant_permission_invalid_ids(authed_client: AsyncClient):
+    """POST /api/v1/dms/files/{invalid}/permissions → 400."""
+    client, seed = authed_client
+    resp = await client.post(
+        "/api/v1/dms/files/bad-uuid/permissions",
+        json={"user_id": str(uuid.uuid4()), "access_level": "read"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_grant_permission_with_group(authed_client: AsyncClient):
+    """POST /api/v1/dms/files/{id}/permissions with group_id → 201."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+    user_id = str(seed["admin_a"].id)
+    group_id = str(uuid.uuid4())
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/permissions",
+        json={"user_id": user_id, "group_id": group_id, "access_level": "read"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 201
+    assert resp.json()["group_id"] == group_id
+
+
+@pytest.mark.asyncio
+async def test_revoke_permission_not_found(authed_client: AsyncClient):
+    """DELETE /api/v1/dms/files/{id}/permissions/{user_id} with no perms → 404."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+    user_id = str(seed["admin_a"].id)
+    resp = await client.delete(
+        f"/api/v1/dms/files/{file_id}/permissions/{user_id}",
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 404
+
+
+@pytest.mark.asyncio
+async def test_revoke_permission_invalid_ids(authed_client: AsyncClient):
+    """DELETE /api/v1/dms/files/{invalid}/permissions/{user_id} → 400."""
+    client, seed = authed_client
+    user_id = str(seed["admin_a"].id)
+    resp = await client.delete(
+        f"/api/v1/dms/files/bad-uuid/permissions/{user_id}",
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_create_share_link_invalid_file_id(authed_client: AsyncClient):
+    """POST /api/v1/dms/files/{invalid}/share-link → 400."""
+    client, seed = authed_client
+    resp = await client.post(
+        "/api/v1/dms/files/bad-uuid/share-link",
+        json={"access_level": "download"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_revoke_share_link_not_found(authed_client: AsyncClient):
+    """DELETE /api/v1/dms/share-links/{nonexistent} → 404."""
+    client, seed = authed_client
+    resp = await client.delete(f"/api/v1/dms/share-links/{uuid.uuid4()}", headers=ORIGIN_HEADER)
+    assert resp.status_code == 404
+
+
+@pytest.mark.asyncio
+async def test_revoke_share_link_invalid_id(authed_client: AsyncClient):
+    """DELETE /api/v1/dms/share-links/{invalid} → 400."""
+    client, seed = authed_client
+    resp = await client.delete("/api/v1/dms/share-links/bad-uuid", headers=ORIGIN_HEADER)
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_public_access_not_found(authed_client: AsyncClient):
+    """GET /api/public/share/{nonexistent} → 404."""
+    client, seed = authed_client
+    resp = await client.get("/api/public/share/nonexistent-token-xyz")
+    assert resp.status_code == 404
+
+
+@pytest.mark.asyncio
+async def test_public_access_post_not_found(authed_client: AsyncClient):
+    """POST /api/public/share/{nonexistent} → 404."""
+    client, seed = authed_client
+    resp = await client.post(
+        "/api/public/share/nonexistent-token-xyz",
+        json={"password": "test"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 404
+
+
+@pytest.mark.asyncio
+async def test_public_access_post_expired(authed_client: AsyncClient):
+    """POST /api/public/share/{token} with expired link → 410."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+    past = datetime.now(timezone.utc) - timedelta(hours=1)
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/share-link",
+        json={"expires_at": past.isoformat(), "access_level": "download"},
+        headers=ORIGIN_HEADER,
+    )
+    token = resp.json()["token"]
+    resp = await client.post(
+        f"/api/public/share/{token}",
+        json={"password": "test"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 410
+
+
+@pytest.mark.asyncio
+async def test_public_access_post_no_password_required(authed_client: AsyncClient):
+    """POST /api/public/share/{token} for link without password → 200."""
+    client, seed = authed_client
+    file_id = str(uuid.uuid4())
+    resp = await client.post(
+        f"/api/v1/dms/files/{file_id}/share-link",
+        json={"access_level": "preview"},
+        headers=ORIGIN_HEADER,
+    )
+    token = resp.json()["token"]
+    resp = await client.post(
+        f"/api/public/share/{token}",
+        json={},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    assert resp.json()["has_password"] is False

tests/test_tags.py

@@ -0,0 +1,490 @@
+"""Tests for Tags plugin — CRUD, assignment, bulk assign, cascade delete, counts."""
+
+from __future__ import annotations
+
+import uuid
+
+import pytest
+import pytest_asyncio
+from httpx import ASGITransport, AsyncClient
+from sqlalchemy import text
+from sqlalchemy.ext.asyncio import AsyncEngine, async_sessionmaker, AsyncSession
+
+from app.core.db import Base, reset_engine_for_testing, close_engine
+from app.core.service_container import get_container
+from app.main import create_app
+from app.plugins.registry import get_registry, reset_registry_for_testing
+from app.plugins.builtins.tags import TagsPlugin
+from app.services.plugin_service import reset_plugin_service_for_testing
+from tests.conftest import seed_tenant_and_users, login_client, ORIGIN_HEADER
+
+
+@pytest_asyncio.fixture
+async def plugin_app(engine: AsyncEngine, redis_client):
+    """FastAPI app with tags plugin registered."""
+    reset_engine_for_testing(engine)
+    app = create_app()
+
+    registry = reset_registry_for_testing()
+    registry.initialize(engine, app)
+
+    container = get_container()
+    await container.initialize()
+
+    registry.register_plugin(TagsPlugin())
+    reset_plugin_service_for_testing(registry)
+
+    yield app
+    await close_engine()
+
+
+@pytest_asyncio.fixture
+async def plugin_client(plugin_app) -> AsyncClient:
+    transport = ASGITransport(app=plugin_app)
+    async with AsyncClient(transport=transport, base_url="http://test") as c:
+        yield c
+
+
+@pytest_asyncio.fixture
+async def authed_client(plugin_client: AsyncClient, db_session: AsyncSession) -> AsyncClient:
+    """Authenticated admin client with seeded data."""
+    seed = await seed_tenant_and_users(db_session)
+    await login_client(plugin_client, "admin@tenanta.com")
+    # Install + activate the tags plugin
+    resp = await plugin_client.post("/api/v1/plugins/tags/install", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    resp = await plugin_client.post("/api/v1/plugins/tags/activate", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    return plugin_client
+
+
+@pytest.mark.asyncio
+async def test_list_tags_empty(authed_client: AsyncClient):
+    """AC6: GET /api/v1/tags → 200 + tags with counts (empty)."""
+    resp = await authed_client.get("/api/v1/tags", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    assert resp.json() == []
+
+
+@pytest.mark.asyncio
+async def test_create_tag(authed_client: AsyncClient):
+    """AC7: POST /api/v1/tags → 201, tag created."""
+    resp = await authed_client.post(
+        "/api/v1/tags",
+        json={"name": "Important", "color": "#FF0000"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 201
+    data = resp.json()
+    assert data["name"] == "Important"
+    assert data["color"] == "#FF0000"
+    assert data["entity_count"] == 0
+
+
+@pytest.mark.asyncio
+async def test_list_tags_with_counts(authed_client: AsyncClient):
+    """AC6: GET /api/v1/tags → 200 + tags with counts."""
+    # Create a tag
+    resp = await authed_client.post(
+        "/api/v1/tags",
+        json={"name": "VIP", "color": "#00FF00"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 201
+    tag_id = resp.json()["id"]
+
+    # List tags — should show entity_count=0
+    resp = await authed_client.get("/api/v1/tags", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    data = resp.json()
+    assert len(data) == 1
+    assert data[0]["name"] == "VIP"
+    assert data[0]["entity_count"] == 0
+
+
+@pytest.mark.asyncio
+async def test_update_tag(authed_client: AsyncClient):
+    """AC8: PATCH /api/v1/tags/{id} → 200."""
+    resp = await authed_client.post(
+        "/api/v1/tags",
+        json={"name": "Old Name", "color": "#000000"},
+        headers=ORIGIN_HEADER,
+    )
+    tag_id = resp.json()["id"]
+
+    resp = await authed_client.patch(
+        f"/api/v1/tags/{tag_id}",
+        json={"name": "New Name", "color": "#FFFFFF"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["name"] == "New Name"
+    assert data["color"] == "#FFFFFF"
+
+
+@pytest.mark.asyncio
+async def test_delete_tag_cascade(authed_client: AsyncClient):
+    """AC9: DELETE /api/v1/tags/{id} → 204, cascade delete assignments."""
+    resp = await authed_client.post(
+        "/api/v1/tags",
+        json={"name": "ToDelete", "color": "#123456"},
+        headers=ORIGIN_HEADER,
+    )
+    tag_id = resp.json()["id"]
+
+    # Assign tag to an entity
+    entity_id = str(uuid.uuid4())
+    resp = await authed_client.post(
+        "/api/v1/tags/assign",
+        json={"tag_id": tag_id, "entity_type": "company", "entity_id": entity_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+
+    # Delete tag
+    resp = await authed_client.delete(f"/api/v1/tags/{tag_id}", headers=ORIGIN_HEADER)
+    assert resp.status_code == 204
+
+    # Verify tag is gone
+    resp = await authed_client.get("/api/v1/tags", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    assert len(resp.json()) == 0
+
+
+@pytest.mark.asyncio
+async def test_assign_tag(authed_client: AsyncClient):
+    """AC10: POST /api/v1/tags/assign → 200, tag assigned to entity."""
+    resp = await authed_client.post(
+        "/api/v1/tags",
+        json={"name": "AssignMe", "color": "#FF00FF"},
+        headers=ORIGIN_HEADER,
+    )
+    tag_id = resp.json()["id"]
+    entity_id = str(uuid.uuid4())
+
+    resp = await authed_client.post(
+        "/api/v1/tags/assign",
+        json={"tag_id": tag_id, "entity_type": "company", "entity_id": entity_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["tag_id"] == tag_id
+    assert data["entity_type"] == "company"
+    assert data["entity_id"] == entity_id
+    assert data["already_assigned"] is False
+
+    # Verify count increased
+    resp = await authed_client.get("/api/v1/tags", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    assert resp.json()[0]["entity_count"] == 1
+
+
+@pytest.mark.asyncio
+async def test_unassign_tag(authed_client: AsyncClient):
+    """AC11: DELETE /api/v1/tags/assign → 204, tag removed."""
+    resp = await authed_client.post(
+        "/api/v1/tags",
+        json={"name": "UnassignMe", "color": "#AAAAAA"},
+        headers=ORIGIN_HEADER,
+    )
+    tag_id = resp.json()["id"]
+    entity_id = str(uuid.uuid4())
+
+    # Assign first
+    resp = await authed_client.post(
+        "/api/v1/tags/assign",
+        json={"tag_id": tag_id, "entity_type": "contact", "entity_id": entity_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+
+    # Unassign
+    resp = await authed_client.request(
+        "DELETE",
+        "/api/v1/tags/assign",
+        json={"tag_id": tag_id, "entity_type": "contact", "entity_id": entity_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 204
+
+
+@pytest.mark.asyncio
+async def test_bulk_assign_tags(authed_client: AsyncClient):
+    """AC12: POST /api/v1/tags/bulk-assign → 200, multiple tags assigned."""
+    tag_ids = []
+    for i in range(3):
+        resp = await authed_client.post(
+            "/api/v1/tags",
+            json={"name": f"BulkTag{i}", "color": "#0000FF"},
+            headers=ORIGIN_HEADER,
+        )
+        tag_ids.append(resp.json()["id"])
+
+    entity_id = str(uuid.uuid4())
+    resp = await authed_client.post(
+        "/api/v1/tags/bulk-assign",
+        json={"tag_ids": tag_ids, "entity_type": "file", "entity_id": entity_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["total"] == 3
+    assert len(data["assigned"]) == 3
+    assert len(data["already_assigned"]) == 0
+
+
+@pytest.mark.asyncio
+async def test_list_tag_entities(authed_client: AsyncClient):
+    """GET /api/v1/tags/{id}/entities → 200, list entities with this tag."""
+    resp = await authed_client.post(
+        "/api/v1/tags",
+        json={"name": "EntitiesTag", "color": "#FF8800"},
+        headers=ORIGIN_HEADER,
+    )
+    tag_id = resp.json()["id"]
+
+    entity_ids = [str(uuid.uuid4()) for _ in range(2)]
+    for eid in entity_ids:
+        await authed_client.post(
+            "/api/v1/tags/assign",
+            json={"tag_id": tag_id, "entity_type": "company", "entity_id": eid},
+            headers=ORIGIN_HEADER,
+        )
+
+    resp = await authed_client.get(f"/api/v1/tags/{tag_id}/entities", headers=ORIGIN_HEADER)
+    assert resp.status_code == 200
+    data = resp.json()
+    assert len(data) == 2
+
+
+@pytest.mark.asyncio
+async def test_create_tag_duplicate(authed_client: AsyncClient):
+    """POST /api/v1/tags with existing name → 409."""
+    resp = await authed_client.post(
+        "/api/v1/tags",
+        json={"name": "DupeTag", "color": "#111111"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 201
+    resp = await authed_client.post(
+        "/api/v1/tags",
+        json={"name": "DupeTag", "color": "#222222"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 409
+
+
+@pytest.mark.asyncio
+async def test_update_tag_not_found(authed_client: AsyncClient):
+    """PATCH /api/v1/tags/{nonexistent} → 404."""
+    resp = await authed_client.patch(
+        f"/api/v1/tags/{uuid.uuid4()}",
+        json={"name": "NewName"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 404
+
+
+@pytest.mark.asyncio
+async def test_update_tag_invalid_id(authed_client: AsyncClient):
+    """PATCH /api/v1/tags/{invalid_uuid} → 400."""
+    resp = await authed_client.patch(
+        "/api/v1/tags/not-a-uuid",
+        json={"name": "NewName"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_update_tag_duplicate_name(authed_client: AsyncClient):
+    """PATCH /api/v1/tags/{id} with existing name → 409."""
+    resp = await authed_client.post(
+        "/api/v1/tags", json={"name": "TagA", "color": "#AAAAAA"}, headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 201
+    resp = await authed_client.post(
+        "/api/v1/tags", json={"name": "TagB", "color": "#BBBBBB"}, headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 201
+    tag_b_id = resp.json()["id"]
+    resp = await authed_client.patch(
+        f"/api/v1/tags/{tag_b_id}",
+        json={"name": "TagA"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 409
+
+
+@pytest.mark.asyncio
+async def test_update_tag_color_only(authed_client: AsyncClient):
+    """PATCH /api/v1/tags/{id} with only color → 200."""
+    resp = await authed_client.post(
+        "/api/v1/tags", json={"name": "ColorTag", "color": "#CCCCCC"}, headers=ORIGIN_HEADER,
+    )
+    tag_id = resp.json()["id"]
+    resp = await authed_client.patch(
+        f"/api/v1/tags/{tag_id}",
+        json={"color": "#DDDDDD"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    assert resp.json()["color"] == "#DDDDDD"
+
+
+@pytest.mark.asyncio
+async def test_delete_tag_not_found(authed_client: AsyncClient):
+    """DELETE /api/v1/tags/{nonexistent} → 404."""
+    resp = await authed_client.delete(f"/api/v1/tags/{uuid.uuid4()}", headers=ORIGIN_HEADER)
+    assert resp.status_code == 404
+
+
+@pytest.mark.asyncio
+async def test_delete_tag_invalid_id(authed_client: AsyncClient):
+    """DELETE /api/v1/tags/{invalid} → 400."""
+    resp = await authed_client.delete("/api/v1/tags/bad-uuid", headers=ORIGIN_HEADER)
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_assign_tag_invalid_entity_type(authed_client: AsyncClient):
+    """POST /api/v1/tags/assign with invalid entity_type → 400."""
+    resp = await authed_client.post(
+        "/api/v1/tags", json={"name": "ETTag", "color": "#EEEEEE"}, headers=ORIGIN_HEADER,
+    )
+    tag_id = resp.json()["id"]
+    resp = await authed_client.post(
+        "/api/v1/tags/assign",
+        json={"tag_id": tag_id, "entity_type": "invalid", "entity_id": str(uuid.uuid4())},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_assign_tag_not_found(authed_client: AsyncClient):
+    """POST /api/v1/tags/assign with nonexistent tag → 404."""
+    resp = await authed_client.post(
+        "/api/v1/tags/assign",
+        json={"tag_id": str(uuid.uuid4()), "entity_type": "company", "entity_id": str(uuid.uuid4())},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 404
+
+
+@pytest.mark.asyncio
+async def test_assign_tag_already_assigned(authed_client: AsyncClient):
+    """POST /api/v1/tags/assign twice → already_assigned=True."""
+    resp = await authed_client.post(
+        "/api/v1/tags", json={"name": "DupAssign", "color": "#FFFFFF"}, headers=ORIGIN_HEADER,
+    )
+    tag_id = resp.json()["id"]
+    entity_id = str(uuid.uuid4())
+    resp = await authed_client.post(
+        "/api/v1/tags/assign",
+        json={"tag_id": tag_id, "entity_type": "company", "entity_id": entity_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    assert resp.json()["already_assigned"] is False
+    resp = await authed_client.post(
+        "/api/v1/tags/assign",
+        json={"tag_id": tag_id, "entity_type": "company", "entity_id": entity_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    assert resp.json()["already_assigned"] is True
+
+
+@pytest.mark.asyncio
+async def test_assign_tag_invalid_ids(authed_client: AsyncClient):
+    """POST /api/v1/tags/assign with invalid tag_id → 400."""
+    resp = await authed_client.post(
+        "/api/v1/tags/assign",
+        json={"tag_id": "bad", "entity_type": "company", "entity_id": str(uuid.uuid4())},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 400
+
+
+@pytest.mark.asyncio
+async def test_unassign_tag_not_found(authed_client: AsyncClient):
+    """DELETE /api/v1/tags/assign with nonexistent assignment → 404."""
+    resp = await authed_client.post(
+        "/api/v1/tags", json={"name": "Unassign404", "color": "#ABABAB"}, headers=ORIGIN_HEADER,
+    )
+    tag_id = resp.json()["id"]
+    resp = await authed_client.request(
+        "DELETE",
+        "/api/v1/tags/assign",
+        json={"tag_id": tag_id, "entity_type": "company", "entity_id": str(uuid.uuid4())},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 404
+
+
+@pytest.mark.asyncio
+async def test_bulk_assign_invalid_entity_type(authed_client: AsyncClient):
+    """POST /api/v1/tags/bulk-assign with invalid entity_type → 400."""
+    resp = await authed_client.post(
+        "/api/v1/tags", json={"name": "BulkBad", "color": "#000001"}, headers=ORIGIN_HEADER,
+    )
+    tag_id = resp.json()["id"]
+    resp = await authed_client.post(
+        "/api/v1/tags/bulk-assign",
+        json={"tag_ids": [tag_id], "entity_type": "invalid", "entity_id": str(uuid.uuid4())},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_bulk_assign_tag_not_found(authed_client: AsyncClient):
+    """POST /api/v1/tags/bulk-assign with nonexistent tag → 404."""
+    resp = await authed_client.post(
+        "/api/v1/tags/bulk-assign",
+        json={"tag_ids": [str(uuid.uuid4())], "entity_type": "file", "entity_id": str(uuid.uuid4())},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 404
+
+
+@pytest.mark.asyncio
+async def test_bulk_assign_already_assigned(authed_client: AsyncClient):
+    """POST /api/v1/tags/bulk-assign twice → already_assigned populated."""
+    resp = await authed_client.post(
+        "/api/v1/tags", json={"name": "BulkDup1", "color": "#001100"}, headers=ORIGIN_HEADER,
+    )
+    tag_id = resp.json()["id"]
+    entity_id = str(uuid.uuid4())
+    resp = await authed_client.post(
+        "/api/v1/tags/bulk-assign",
+        json={"tag_ids": [tag_id], "entity_type": "file", "entity_id": entity_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    resp = await authed_client.post(
+        "/api/v1/tags/bulk-assign",
+        json={"tag_ids": [tag_id], "entity_type": "file", "entity_id": entity_id},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200
+    data = resp.json()
+    assert len(data["already_assigned"]) == 1
+    assert len(data["assigned"]) == 0
+
+
+@pytest.mark.asyncio
+async def test_list_tag_entities_not_found(authed_client: AsyncClient):
+    """GET /api/v1/tags/{nonexistent}/entities → 404."""
+    resp = await authed_client.get(f"/api/v1/tags/{uuid.uuid4()}/entities", headers=ORIGIN_HEADER)
+    assert resp.status_code == 404
+
+
+@pytest.mark.asyncio
+async def test_list_tag_entities_invalid_id(authed_client: AsyncClient):
+    """GET /api/v1/tags/{invalid}/entities → 400."""
+    resp = await authed_client.get("/api/v1/tags/bad-uuid/entities", headers=ORIGIN_HEADER)
+    assert resp.status_code == 400