TGK/1 — Trace Graph Kernel Semantics

Status: Draft Owner: Architecture Version: 0.1.0 SoT: No Last Updated: 2025-11-30 Tags: [tgk, determinism, index, federation]

Document ID: TGK/1 Layer: L1 — Semantic graph layer over ASL artifacts and PERs (no encodings)

Depends on (normative):

ASL/1-CORE
ASL/1-CORE-INDEX
ASL/LOG/1
ASL/SYSTEM/1

Informative references:

ENC-TGK1-EDGE (core edge encoding, if present)
ENC-TGK-INDEX (index encoding draft)
ASL/INDEX-ACCEL/1
ENC-ASL-CORE-INDEX

0. Conventions

The key words MUST, MUST NOT, REQUIRED, SHOULD, and MAY are to be interpreted as in RFC 2119.

TGK/1 defines semantic meaning only. It does not define storage formats, on-disk encodings, or execution operators.

1. Purpose & Scope

TGK/1 defines the semantic layer for Trace Graph Kernel (TGK) edges that relate ASL artifacts and PERs. It keeps TGK thin and deterministic by reusing ASL index and log semantics.

Non-goals:

New encodings for edges or indexes
Query operators or execution plans
Federation protocols or transport
Re-definition of ASL or PEL semantics

2. TGK Objects

2.1 TGK Edge

A TGK Edge is an immutable record representing a directed relationship between ASL artifacts and/or PERs. TGK edges are semantic overlays and MUST NOT redefine or bypass ASL identity. TGK/1-CORE defines the EdgeBody structure with ordered from/to lists; TGK/1 does not further constrain cardinality.

2.2 Canonical Edge Key

Each TGK edge has a Canonical Edge Key that uniquely identifies it. The Canonical Edge Key MUST be derived from the logical EdgeBody defined in TGK/1-CORE, preserving list order and multiplicity:

from: ordered list of source node identifiers (MAY be empty)
to: ordered list of destination node identifiers (MAY be empty)
payload: reference carried by the edge
type: edge type identifier
Projection context (for example, PER or execution identity) when not already captured by the edge payload or type profile

Classification attributes (edge type keys, labels) MUST NOT affect canonical identity.

3. Index and Visibility (Normative)

TGK edges are indexed objects and inherit visibility from the ASL index and log:

A TGK edge becomes visible only when its index record is admitted by a sealed segment and log order (ASL/LOG/1).
TGK traversal and lookup MUST NOT bypass index visibility or log ordering.
For a fixed {Snapshot, LogPrefix}, TGK edge lookup and shadowing MUST be deterministic (ASL/1-CORE-INDEX).
Tombstones and shadowing semantics follow ASL/1-CORE-INDEX and ASL/LOG/1 replay order.

4. Deterministic Traversal (Normative)

TGK traversal operates over a snapshot/log-bounded view:

Inputs: {Snapshot, LogPrefix} and a seed set (nodes or edges).
Outputs: only edges visible under the same {Snapshot, LogPrefix}.
Traversal MUST be deterministic and replay-compatible with ASL/LOG/1.

Deterministic ordering for traversal output MUST be:

logseq ascending
Canonical Edge Key as tie-break

Acceleration structures MAY be used but MUST NOT change semantics.

5. Federation Alignment (Normative)

Federation does not change TGK semantics. It only propagates edges and artifacts that are already visible under index rules.

Domain visibility and publication status are enforced via index metadata (ENC-ASL-CORE-INDEX).
TGK edges keep canonical identity across domains.
Cross-domain propagation MUST preserve snapshot/log determinism.

6. Non-Goals

TGK/1 does not define:

Edge encoding or storage layout
Index segment formats
Query languages or execution plans
Acceleration rules beyond ASL/INDEX-ACCEL/1

7. Normative Invariants

Conforming implementations MUST enforce:

TGK edges are immutable and indexed objects.
No TGK visibility without index admission and log ordering.
Traversal is snapshot/log bounded and deterministic.
Federation does not alter TGK semantics; it only propagates visible edges.
Edge classification is not part of canonical identity.

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