Phase 3: Graph view, backlinks, quick switcher, export

- Add outgoing_links (JSON) and backlinks_count to Document model
- POST /documents/{id}/detect-links — detect [[uuid]] patterns in content
- GET /documents/{id}/backlinks — documents referencing this doc
- GET /documents/{id}/outgoing-links — documents this doc references
- GET /documents/{id}/links — combined incoming + outgoing
- GET /projects/{id}/graph — full project relationship graph
- GET /search/quick — fuzzy search (Quick Switcher Cmd+K)
- GET /projects/{id}/documents/search — project-scoped search
- GET /documents/{id}/export — markdown|json export
- GET /projects/{id}/export — json|zip export
- 27 new tests

app/schemas/document.py

@@ -145,3 +145,122 @@ class DocumentBriefResponse(BaseModel):
 
 class DocumentListResponse(BaseModel):
     documents: list[DocumentBriefResponse]
+
+
+# =============================================================================
+# Phase 3: Link Detection & Graph Schemas
+# =============================================================================
+
+class DetectLinksRequest(BaseModel):
+    content: str = Field(..., max_length=5_000_000)  # ~5MB limit
+
+
+class BrokenLink(BaseModel):
+    reference: str
+    reason: str  # "document_not_found" | "invalid_format"
+
+
+class DetectLinksResponse(BaseModel):
+    document_id: str
+    outgoing_links: list[str]
+    links_detected: int
+    links_broken: int
+    broken_links: list[BrokenLink] = []
+
+
+class BacklinkItem(BaseModel):
+    document_id: str
+    title: str
+    project_id: str
+    project_name: str
+    excerpt: str
+    updated_at: datetime
+
+
+class BacklinksResponse(BaseModel):
+    document_id: str
+    backlinks_count: int
+    backlinks: list[BacklinkItem]
+
+
+class OutgoingLinkItem(BaseModel):
+    document_id: str
+    title: str
+    project_id: str
+    project_name: str
+    exists: bool
+    updated_at: datetime | None
+
+
+class OutgoingLinksResponse(BaseModel):
+    document_id: str
+    outgoing_links_count: int
+    outgoing_links: list[OutgoingLinkItem]
+
+
+class LinkItem(BaseModel):
+    document_id: str
+    title: str
+    anchor_text: str | None = None
+
+
+class LinksResponse(BaseModel):
+    document_id: str
+    outgoing_links: list[LinkItem]
+    backlinks: list[LinkItem]
+
+
+class GraphNode(BaseModel):
+    id: str
+    title: str
+    type: str = "document"
+
+
+class GraphEdge(BaseModel):
+    source: str
+    target: str
+    type: str = "reference"
+
+
+class GraphStats(BaseModel):
+    total_documents: int
+    total_references: int
+    orphaned_documents: int
+
+
+class GraphResponse(BaseModel):
+    project_id: str
+    nodes: list[GraphNode]
+    edges: list[GraphEdge]
+    stats: GraphStats
+
+
+# =============================================================================
+# Phase 3: Export Schemas
+# =============================================================================
+
+class DocumentExportResponse(BaseModel):
+    """Used for JSON export format."""
+    id: str
+    title: str
+    content: str
+    tiptap_content: dict[str, Any] | None = None
+    created_at: datetime
+    updated_at: datetime
+    metadata: dict[str, Any] = Field(default_factory=dict)
+
+
+class ProjectExportDocument(BaseModel):
+    id: str
+    title: str
+    content: str
+    tiptap_content: dict[str, Any] | None = None
+    outgoing_links: list[str] = []
+    metadata: dict[str, Any] = Field(default_factory=dict)
+
+
+class ProjectExportResponse(BaseModel):
+    project: dict[str, Any]
+    documents: list[ProjectExportDocument]
+    exported_at: datetime
+    format_version: str = "3.0"