Edge Types

Edge types classify the relationships in the contextual graph. They are the relationship equivalent of entity types: every grounded or inferred edge has a type value that maps to one row in the edge_types registry, and that row defines how the relationship is described, exported, and used by prompts.

What edge types control

Each edge type carries four values:

UI label	API field	Purpose
Type Name	type_name	Machine name used in cge_type and in model output. Lowercase letters, digits, and hyphens only.
Description	description	Human-readable meaning shown in the UI and in the edge-vocabulary prompt.
C4 Description	c4_description	Relationship label used in C4 (Structurizr DSL and Mermaid) exports.
ArchiMate Relationship	archimate_relationship	Standard ArchiMate relationship type used in ArchiMate XML exports.

The C4 and ArchiMate mappings behave the same way as the mappings on entity types: the exporters read the stored value directly and only fall back to a default when the mapping is empty. The default for an unmapped edge relationship is Association.

Where you manage edge types

Edge types are managed on the Entities page, in the Edge Types tab. The tab lists every type with columns for Type Name, Description, C4 Description, ArchiMate Relationship, and Created.

Creating a type

1. Click Create edge type.
2. Enter a Type Name (slug-style, e.g. consumes-from).
3. Enter a Description (required).
4. Optionally enter a C4 Description (e.g. consumes events from).
5. Optionally choose an ArchiMate Relationship from the standard list.

Editing a type

Click any edge-type row to open Edge Type Details. You can change the description, C4 description, and ArchiMate relationship. The type name can also be edited, but it must stay globally unique and slug-formatted.

Deleting types

Select one or more rows and click Delete. Deletion is blocked if any contextual-graph edge still references the type.

Standard seeded edge types

architxt ships with five standard edge types that cover the most common system interactions. They are created automatically when the schema is initialized:

Type name	Description	C4 description	ArchiMate relationship
calls	A calls or invokes a service or interface on B.	invokes or calls to	serving
sends	A sends data or an event to B.	sends data or an event to	flow
reads	A reads data from B.	reads data from	access
writes	A persists or writes data to B.	persists or writes data to	access
depends-on	A depends on B. Use only when no more specific type applies.	depends on	association

You can add custom types for domain-specific relationships (for example notifies, owns, hosts). Custom types appear in the edge-vocabulary prompt and can be emitted by edge-context models just like the standard ones.

Edge types in the contextual graph

• Grounded edges imported from Hindsight keep their original relationship type if it matches an edge_types row.
• Edge-context mental models emit edges with a type field. The type must be one of the registered edge types.
• If a model emits a type that does not exist in the registry, the edge is still created, but exporters treat it as unmapped and fall back to the default relationship.

Edge vocabulary prompt

The Preview edge vocabulary prompt button on the Edge Types tab shows the exact markdown fragment that is injected into contextual-graph prompts as the {{ARCHITXT_EDGE_VOCABULARY}} variable. This fragment lists every registered edge type with its description and direction rule, so you can verify what models are being told to use.

Edge-context properties

When an edge-context model returns a table, the following columns are recognised and carried through into the edge's properties bag:

Column	Stored as	Example values
protocol	protocol	HTTPS, gRPC, SFTP, Kafka, RabbitMQ, file drop
format	format	JSON, XML, CSV, Avro, protobuf, REST, SOAP
frequency	frequency	real-time, on-demand, hourly, nightly, ad-hoc
auth	auth	OAuth 2.0, mTLS, API key, JWT, IP allowlist
encryption	encryption	TLS 1.3, AES-256-GCM at rest, GPG signed

Any additional columns in the table are also carried through into properties, so the contract stays open to future fields. Unknown or unsupported values should be emitted as - or left blank; architxt normalises them to empty strings before storage.

These properties appear on the edge in the Graph tab and are included in JSON and CSV exports.

How edge types relate to other concepts

• Entity types define the nodes at each end of an edge.
• Contextual Graph shows the edges that use these types.
• Contextual Mental Models — especially the sys_edge_context role — produce the edges and properties described here.
• Graph exports use the C4 and ArchiMate mappings on edge types.

Summary

Edge types are the central registry for relationship semantics in architxt. They give every contextual-graph edge a consistent type name, a human description, a C4 relationship label, and an ArchiMate relationship type, and they feed the edge vocabulary that guides model output.