JAC: Declared Dependency Graphs for JEP Events and Receipts

3.1. JAC-2 Defines

JAC-2 defines:¶

• one profile identifier;¶
• one critical dependency extension;¶
• zero-or-more parent links per JEP event;¶
• logical JEP-event parent references using Event Identity;¶
• optional exact-artifact pinning using Event Hash;¶
• digest-addressed non-JEP parent references;¶
• partial-fragment and unresolved-parent semantics;¶
• cycle detection for resolved dependency fragments;¶
• independent JAC validation checks;¶
• dependency-graph validation result semantics.¶

3.2. JAC-2 Does Not Define

JAC-2 does not define:¶

• new JEP verbs;¶
• a new event format;¶
• a new signature or hash format;¶
• a replacement for Event Identity or Event Hash;¶
• automatic delegation, authorization, or termination propagation;¶
• factual causality;¶
• complete real-world history;¶
• responsibility, fault, negligence, intent, fairness, or entitlement;¶
• task, workflow, state-machine, handoff, or result semantics;¶
• legal liability or regulatory compliance;¶
• a mandatory bundle, transport, archive, or ledger.¶

3.3. Declared Dependency

A signed statement that the current JEP event depends on or is based on an identified parent according to the relation semantics selected for the link.¶

The baseline relation defined by JAC-2 is declared-dependency.¶

3.4. Parent

The object referenced by one JAC dependency link.¶

A parent MAY be:¶

• a JEP event identified by Event Identity;¶
• a digest-addressed receipt record;¶
• another digest-addressed external record.¶

3.5. Dependency Fragment

A set of JEP events and referenced parent objects observed together for JAC validation.¶

A Dependency Fragment is partial by default.¶

JAC retains the term "chain" for continuity, but the JAC-2 baseline data model is a directed dependency graph: it MAY branch and join because an event can declare zero or more parents.¶

3.6. Resolved Parent

A parent for which the verifier has obtained the referenced object or exact artifact needed by the requested validation context.¶

3.7. Unresolved Parent

A syntactically valid parent reference for which the referenced object is not available or cannot be resolved in the requested validation context.¶

An unresolved parent is not proof that the parent does not exist.¶

4.1. JAC-2 Profile Identifier

The profile identifier is:¶

https://humanjudgment.org/jep/profiles/jac/2

The human-readable label JAC-2 MAY be used in documentation.¶

The identifier is a publisher-controlled HTTPS URI. Dereferencing it is not required for validation.¶

4.2. Dependency Extension Identifier

The dependency extension identifier is:¶

https://humanjudgment.org/jep/extensions/dependency/2

A JEP event claiming JAC-2 conformance MUST carry this extension in ext and MUST list the extension identifier in ext_crit.¶

A verifier that cannot process this critical extension cannot claim successful JAC-2 validation.¶

4.3. Version Boundary

JAC-2 is not wire-compatible with JAC-Core-1 from draft-wang-jac-02.¶

JAC-Core-1 used a single digest-oriented based_on link and commonly treated JEP Event Hash as the parent-event reference. JAC-2 instead supports multiple parents and uses Event Identity for logical JEP event references.¶

Historical JAC-Core-1 events MUST NOT be silently rewritten as JAC-2 events.¶

6.1. Extension Shape

The JAC-2 dependency extension MUST be a JSON object containing:¶

• profile¶
• parents¶

profile MUST equal https://humanjudgment.org/jep/profiles/jac/2.¶

parents MUST be a JSON array containing zero or more Parent Link objects.¶

An empty parents array declares that the event is a JAC root in the observed dependency structure. It does not prove that the event had no external predecessors in the real world.¶

No other members are defined by the JAC-2 baseline extension.¶

The order of entries in parents has no semantic meaning.¶

6.2. Parent Link

A Parent Link MUST be a JSON object containing:¶

• relation¶
• parent¶

relation MUST equal declared-dependency for the JAC-2 baseline.¶

parent MUST be a Parent Reference defined in Section 6.3.¶

A future profile MAY define additional relation identifiers. Such identifiers MUST be absolute URIs, MUST be collision-resistant, and MUST define:¶

• exact edge semantics;¶
• required parent fields;¶
• graph-processing rules;¶
• cycle rules if different from JAC-2;¶
• non-inference boundaries.¶

An additional relation MUST NOT silently redefine declared-dependency.¶

6.3. Parent Reference

A Parent Reference MUST be a JSON object containing kind.¶

kind MUST be one of:¶

• jep-event¶
• digest-record¶

JEP Event Parent¶

When kind is jep-event, the Parent Reference MUST contain event_identity.¶

event_identity MUST be an object containing non-empty string members who and id.¶

The Parent Reference MAY additionally contain:¶

• event_hash¶
• uri¶

event_hash, when present, MUST be a valid JEP algorithm-tagged digest string and pins one exact signed artifact for the identified event.¶

uri, when present, is a retrieval hint only.¶

The logical dependency node is Event Identity, not Event Hash.¶

A verifier MUST NOT create two logical JAC nodes merely because two valid signed artifacts for the same Event Identity have different Event Hash values.¶

If the same Event Identity resolves to conflicting unsigned JEP event content, JEP Event Identity conflict processing applies and JAC dependency-graph validation MUST NOT report success.¶

Digest Record Parent¶

When kind is digest-record, the Parent Reference MUST contain digest.¶

digest MUST be an algorithm-tagged digest string.¶

The Parent Reference MAY additionally contain:¶

• profile¶
• record_type¶
• media_type¶
• uri¶

If present, profile MUST be an absolute URI, record_type and media_type MUST be non-empty strings, and uri MUST be an absolute URI.¶

These members are descriptive and MUST NOT replace digest integrity.¶

If profile equals https://humanjudgment.org/jep/profiles/receipt/1, the referenced record is claiming the JEP Receipt Profile namespace. A verifier MUST NOT claim Receipt Profile validity unless that record was separately validated under the applicable Receipt Profile rules.¶

6.4. Duplicate Parent Links

Within one dependency extension, two Parent Links MUST NOT identify the same logical parent under the same relation.¶

For jep-event, logical equality is Event Identity equality.¶

For digest-record, logical equality is exact digest-string equality.¶

A producer MAY refer to the same logical parent under two different profile-defined relations only when the semantics of those relations require that distinction.¶

6.5. Self-Dependency

A JAC event MUST NOT contain a jep-event parent whose Event Identity equals the current event's Event Identity.¶

A self-dependency is a JAC structural failure.¶

7.1. JAC Root

{
  "jep": "1",
  "id": "urn:uuid:018f4f8d-0000-7000-8000-000000000001",
  "verb": "J",
  "who": "did:example:agent-a",
  "when": 1790424000,
  "what": {
    "claim": "begin-analysis"
  },
  "ext": {
    "https://humanjudgment.org/jep/extensions/dependency/2": {
      "profile": "https://humanjudgment.org/jep/profiles/jac/2",
      "parents": []
    }
  },
  "ext_crit": [
    "https://humanjudgment.org/jep/extensions/dependency/2"
  ],
  "sig": "..."
}

7.2. Single JEP Parent

{
  "jep": "1",
  "id": "urn:uuid:018f4f8d-0000-7000-8000-000000000002",
  "verb": "J",
  "who": "did:example:agent-b",
  "when": 1790424010,
  "what": {
    "claim": "use-prior-analysis"
  },
  "ext": {
    "https://humanjudgment.org/jep/extensions/dependency/2": {
      "profile": "https://humanjudgment.org/jep/profiles/jac/2",
      "parents": [
        {
          "relation": "declared-dependency",
          "parent": {
            "kind": "jep-event",
            "event_identity": {
              "who": "did:example:agent-a",
              "id": "urn:uuid:018f4f8d-0000-7000-8000-000000000001"
            }
          }
        }
      ]
    }
  },
  "ext_crit": [
    "https://humanjudgment.org/jep/extensions/dependency/2"
  ],
  "sig": "..."
}

7.3. Multiple Parents with Exact Artifact Pin

{
  "profile": "https://humanjudgment.org/jep/profiles/jac/2",
  "parents": [
    {
      "relation": "declared-dependency",
      "parent": {
        "kind": "jep-event",
        "event_identity": {
          "who": "did:example:agent-a",
          "id": "urn:uuid:018f4f8d-0000-7000-8000-000000000001"
        },
        "event_hash": "sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
      }
    },
    {
      "relation": "declared-dependency",
      "parent": {
        "kind": "digest-record",
        "digest": "sha256:bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb",
        "profile": "https://humanjudgment.org/jep/profiles/receipt/1",
        "record_type": "behavior",
        "media_type": "application/json"
      }
    }
  ]
}

The second example fragment is the extension value only.¶

8.1. Direction

Each Parent Link creates a directed edge:¶

current event -> declared parent

The edge means only that the current event declares the parent as a dependency under the stated relation.¶

It does not, by itself, mean that the parent caused the current event.¶

8.2. Multiple Parents

A JAC event MAY declare multiple parents.¶

Multiple parents do not imply equal weight, joint sufficiency, complete input coverage, or causal exhaustiveness.¶

JAC-2 does not define a parent ordering.¶

8.3. Roots

An event with an empty parents array is a declared JAC root.¶

Root status is local to the declared JAC dependency structure.¶

A root declaration MUST NOT be interpreted as proof that no earlier real-world event, input, instruction, or cause existed.¶

8.4. Acyclicity

The baseline declared-dependency relation is acyclic.¶

A resolved dependency fragment containing a directed cycle under declared-dependency is invalid under JAC-2.¶

Cycle detection operates on logical JEP Event Identity nodes and digest-record digest identities.¶

An unresolved parent cannot by itself prove that a cycle exists or does not exist outside the observed fragment.¶

8.5. Partial Observation

JAC-2 uses an open-world, partial-fragment default.¶

A valid observed fragment does not imply that:¶

• all parents were disclosed;¶
• all relevant events were observed;¶
• all real-world causes were represented;¶
• the fragment is a complete chain;¶
• the declared root is a real-world first cause.¶

A profile claiming complete-log or closed-world semantics MUST define those assumptions explicitly.¶

8.6. Unresolved Parents

An unresolved parent reference MAY remain structurally valid.¶

Whether unresolved parent resolution is required depends on the requested validation context.¶

A verifier MUST NOT convert an unresolved parent into a fabricated success, missing-parent fault, or proof of non-existence.¶

10.1. Layer Separation

A JAC validation result separates:¶

• underlying JEP validation status;¶
• JAC profile checks;¶
• JAC overall status;¶
• fragment completeness statement.¶

JAC MUST NOT overwrite the JEP validation result.¶

10.2. Validation Contexts

JAC-2 defines two profile validation contexts:¶

• link¶
• fragment¶

link validates one event's dependency extension and parent-reference structure. Parent resolution is not required unless exact artifact integrity is explicitly requested.¶

fragment validates an observed multi-node dependency fragment. It requires cycle analysis over all resolved in-scope nodes and evaluates parent integrity according to the requested fragment policy.¶

A JEP implementation MAY invoke JAC fragment validation from JEP chain mode.¶

JAC context names are profile-local and are not new JEP validation modes.¶

10.3. JAC Checks

The initial JAC-2 check identifiers are:¶

• https://humanjudgment.org/jep/profiles/jac/2#profile-binding¶
• https://humanjudgment.org/jep/profiles/jac/2#dependency-extension¶
• https://humanjudgment.org/jep/profiles/jac/2#parent-reference¶
• https://humanjudgment.org/jep/profiles/jac/2#parent-resolution¶
• https://humanjudgment.org/jep/profiles/jac/2#parent-integrity¶
• https://humanjudgment.org/jep/profiles/jac/2#duplicate-parent¶
• https://humanjudgment.org/jep/profiles/jac/2#self-dependency¶
• https://humanjudgment.org/jep/profiles/jac/2#cycle¶
• https://humanjudgment.org/jep/profiles/jac/2#fragment-consistency¶
• https://humanjudgment.org/jep/profiles/jac/2#completeness-assumption¶

Check statuses use the JEP conformance vocabulary:¶

• pass¶
• fail¶
• not_checked¶
• not_applicable¶
• unsupported¶
• indeterminate¶

A verifier MUST NOT report an unperformed JAC check as pass.¶

10.4. Required Link Checks

For link context, the required JAC checks are:¶

• profile-binding¶
• dependency-extension¶
• parent-reference¶
• duplicate-parent¶
• self-dependency¶

parent-resolution and parent-integrity are required only when the requested link-validation policy requires parent material or exact-artifact checking.¶

cycle is not required for isolated link validation.¶

10.5. Required Fragment Checks

For fragment context, the required checks are:¶

• all required link checks for every in-scope JAC event;¶
• parent-resolution for every parent that the requested fragment policy says must be resolved;¶
• parent-integrity for every resolved parent carrying an exact-artifact pin or digest-record reference;¶
• cycle;¶
• fragment-consistency;¶
• completeness-assumption.¶

If a required parent cannot be resolved and no required check has failed, JAC overall status is indeterminate.¶

fragment-consistency passes only when each included JEP Event Identity maps to one non-conflicting unsigned event content, all resolved parent identities are consistent with their references, and multiple artifacts for one Event Identity are treated as one logical node.¶

completeness-assumption passes when the verifier reports partial, or when an explicitly selected completeness profile authorizes complete-under-profile and all checks required by that profile pass.¶

10.6. Completeness Statement

A JAC result MUST report one of:¶

• partial¶
• complete-under-profile¶

The default is partial.¶

complete-under-profile MUST NOT be reported unless an explicitly selected profile defines the closed-world or complete-log assumptions and all required checks for those assumptions passed.¶

JAC-2 alone never establishes real-world causal completeness.¶

10.7. JAC Overall Status

The JAC overall status is one of:¶

• valid¶
• invalid¶
• indeterminate¶

For the requested JAC context:¶

• invalid means the underlying required JEP validation is invalid or at least one required JAC check failed;¶
• indeterminate means no required check failed but the underlying required JEP validation is indeterminate or at least one required JAC check is unsupported, not checked, or indeterminate;¶
• valid means the underlying required JEP validation is valid and every required JAC check passed or was not applicable.¶

valid does not mean causally true or complete.¶

10.8. Validation Procedure

A fragment validator SHOULD:¶

• validate each in-scope JEP event under the requested JEP mode and profiles;¶
• process the critical JAC dependency extension;¶
• verify the JAC profile identifier;¶
• parse and validate all Parent Links;¶
• reject duplicate or self-dependencies;¶
• resolve required parent objects;¶
• verify Event Identity and optional Event Hash pins for JEP-event parents;¶
• verify digest integrity for available digest-record parents;¶
• construct the logical dependency graph;¶
• detect cycles over the resolved in-scope fragment;¶
• evaluate fragment consistency;¶
• evaluate the declared completeness assumption;¶
• return JEP results, JAC checks, JAC overall status, and completeness separately.¶

15.1. JAC-2 Producer

A conforming JAC-2 Producer MUST:¶

• produce a JEP event conforming to the applicable JEP Producer requirements;¶
• include the JAC dependency extension;¶
• list it in ext_crit;¶
• use the JAC-2 profile identifier;¶
• use only defined Parent Reference forms;¶
• use Event Identity for logical JEP-event parents;¶
• use Event Hash only as an optional exact-artifact pin;¶
• reject self-dependency before signing;¶
• avoid duplicate parent links.¶

15.2. JAC-2 Link Verifier

A conforming JAC-2 Link Verifier MUST:¶

• perform or consume an actual JEP validation result;¶
• process the critical dependency extension;¶
• perform all required link checks;¶
• preserve independent check statuses;¶
• distinguish Event Identity from Event Hash;¶
• return indeterminate rather than success when a required check cannot be completed.¶

15.3. JAC-2 Fragment Verifier

A conforming JAC-2 Fragment Verifier MUST additionally:¶

• build graph nodes from logical Event Identity and digest-record identity;¶
• resolve parents required by the selected fragment policy;¶
• verify required exact-artifact and digest pins;¶
• detect baseline declared-dependency cycles;¶
• report fragment completeness explicitly;¶
• avoid inferring omitted parents or real-world causes from a valid fragment.¶