refactor: flatten signatures array directly onto records

Replace the signatureData wrapper object with a direct signatures
property on all record lexicons. app.certified.signature.list is now
a reusable array type (not an object), so records have flat access
at record.signatures[] instead of record.signatureData.signatures[].

This matches the ATProtocol Attestation Specification structure and
eliminates unnecessary nesting while keeping the array definition DRY
via a single shared lexicon ref.

Author: aspiers

.changeset/fuzzy-pandas-smile.md

@@ -9,12 +9,12 @@ Adds optional cryptographic signature support to all record lexicons, enabling p
 **New lexicons:**
 
 - `app.certified.signature.inline` - Inline cryptographic signature object with JOSE algorithm identifiers (ES256, ES256K, Ed25519)
-- `app.certified.signature.list` - Container object with `signatures` array supporting both inline signatures and remote attestation references
+- `app.certified.signature.list` - Reusable array type (union of inline signatures and strongRefs to remote proofs)
 - `app.certified.signature.proof` - Remote attestation proof record containing the CID of attested content
 
 **Changes to existing lexicons:**
 
-All 20 record lexicons now include an optional `signatureData` property that references `app.certified.signature.list`:
+All 20 record lexicons now include an optional `signatures` property (a ref to `app.certified.signature.list`) placed directly on the record with no wrapper object:
 
 - `org.hypercerts.claim.activity`
 - `org.hypercerts.claim.contribution`

ERD.puml

@@ -238,13 +238,6 @@ dataclass signatureInline {
     !endif
 }
 
-' app.certified.signature.list
-dataclass signatureList {
-    !if (SHOW_FIELDS == "true")
-    signatures[]?
-    !endif
-}
-
 ' app.certified.signature.proof
 dataclass signatureProof {
     !if (SHOW_FIELDS == "true")
@@ -426,26 +419,12 @@ badgeAward::subject --> activity
 'badgeAward::subject --[norank]-> collection
 
 ' Signature relationships
-signatureList::signatures --> signatureInline
-signatureList::signatures --> signatureProof : "strongRef"
-
-' signatureData relationships (all record lexicons reference signatureList)
-activity ..> signatureList : signatureData
-collection ..> signatureList : signatureData
-attachment ..> signatureList : signatureData
-measurement ..> signatureList : signatureData
-evaluation ..> signatureList : signatureData
-acknowledgement ..> signatureList : signatureData
-contribution ..> signatureList : signatureData
-contributorInformation ..> signatureList : signatureData
-rights ..> signatureList : signatureData
-fundingReceipt ..> signatureList : signatureData
-workScopeTag ..> signatureList : signatureData
-location ..> signatureList : signatureData
-badgeDefinition ..> signatureList : signatureData
-badgeAward ..> signatureList : signatureData
-badgeResponse ..> signatureList : signatureData
-organization ..> signatureList : signatureData
-linkEvm ..> signatureList : signatureData
+' All record lexicons have an optional `signatures` array (ref to
+' app.certified.signature.list) containing a union of signatureInline
+' objects and strongRefs to signatureProof records. Only activity is
+' shown here to avoid cluttering the diagram; the pattern is identical
+' for all record lexicons.
+activity ..> signatureInline : signatures
+activity ..> signatureProof : "signatures (strongRef)"
 
 @enduml

README.md

@@ -45,7 +45,7 @@ CERTIFIED ─ shared lexicons (certified.app)
   actor/organization        (org metadata)
   badge/definition ──► badge/award ──► badge/response
   signature/inline          (embedded cryptographic signature)
-  signature/list            (container for signatures array)
+  signature/list            (reusable signatures array type)
   signature/proof           (remote attestation proof record)
 ```
 
@@ -157,10 +157,10 @@ await agent.api.com.atproto.repo.createRecord({
 | Lexicon              | NSID                             | Description                                                                                                                                     |
 | -------------------- | -------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------- |
 | **Inline Signature** | `app.certified.signature.inline` | An inline cryptographic signature for attesting to record content. Uses JOSE algorithm identifiers (ES256, ES256K, Ed25519).                    |
-| **Signature List**   | `app.certified.signature.list`   | Container object with a `signatures` array. Referenced by all record lexicons via `signatureData` property.                                     |
+| **Signature List**   | `app.certified.signature.list`   | Reusable array type (union of inline signatures and strongRefs). Referenced by all record lexicons via the `signatures` property.               |
 | **Proof**            | `app.certified.signature.proof`  | Remote attestation proof record containing the CID of attested content. Lives in the attestor's repository and can be referenced via strongRef. |
 
-All record lexicons include an optional `signatureData` property that references `app.certified.signature.list`, enabling cryptographic attestations. See [Cryptographic Signatures](#cryptographic-signatures) for usage details.
+All record lexicons include an optional `signatures` property (a ref to `app.certified.signature.list`) enabling cryptographic attestations. See [Cryptographic Signatures](#cryptographic-signatures) for usage details.
 
 > **Full property tables** → [SCHEMAS.md](SCHEMAS.md)
 
@@ -383,7 +383,7 @@ const attachment = {
 
 ### Cryptographic Signatures
 
-All record lexicons support optional cryptographic signatures via the `signatureData` property. This enables platform attestation and verification that records were created through trusted services.
+All record lexicons support optional cryptographic signatures via the `signatures` property. This enables platform attestation and verification that records were created through trusted services.
 
 Signatures support two patterns:
 
@@ -399,25 +399,23 @@ const signedActivity = {
   title: "Verified Reforestation Project",
   shortDescription: "Planted 1,000 trees in partnership with local community",
   createdAt: new Date().toISOString(),
-  signatureData: {
-    signatures: [
-      // Inline signature (embedded)
-      {
-        $type: "app.certified.signature.inline",
-        signatureType: "ES256K", // JOSE algorithm: secp256k1
-        signature: new Uint8Array([
-          /* signature bytes */
-        ]),
-        key: "did:plc:platform123#signing", // DID verification method
-      },
-      // Remote attestation (reference to proof in another repo)
-      {
-        $type: "com.atproto.repo.strongRef",
-        uri: "at://did:plc:verifier/app.certified.signature.proof/abc123",
-        cid: "bafy...",
-      },
-    ],
-  },
+  signatures: [
+    // Inline signature (embedded)
+    {
+      $type: "app.certified.signature.inline",
+      signatureType: "ES256K", // JOSE algorithm: secp256k1
+      signature: new Uint8Array([
+        /* signature bytes */
+      ]),
+      key: "did:plc:platform123#signing", // DID verification method
+    },
+    // Remote attestation (reference to proof in another repo)
+    {
+      $type: "com.atproto.repo.strongRef",
+      uri: "at://did:plc:verifier/app.certified.signature.proof/abc123",
+      cid: "bafy...",
+    },
+  ],
 };
 ```