feat: trace annotation body for traced citations; paperspec.traces

A trace follows one citation of a sentence of a citing paper to a passage of the
cited paper (spec/18 section 18.5). Minor change: a new body kind, optional
properties and two rules, with no valid file made invalid.

- annotation schema branch (source, selector, reference, note, verdict, proposer;
  proposer required for a Software creator); body_kind in sql/store.sql; the note
  and proposer terms of the JSON-LD context; rules layer.trace.source and
  layer.trace.target.
- paperspec.traces: resolve(annotation, citing_state, cited_state, same_as) gives
  current, changed, stale, unlinked or misresolved with open and cites; problems,
  disputes, disputed.
- fixtures/records/traces/ on writer2027fixed-ynr7.v3 and vectors/traces.jsonl
  (29 cases); check.py runs the record checks over both layers; counts, glossary,
  examples and CHANGELOG updated.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Uy4ZYbWRoCdUtWLEfigysY

schemas/annotation.schema.json

@@ -15,6 +15,50 @@
         "feedback",
         "resource"
       ]
+    },
+    "selector": {
+      "description": "A selector of a passage: the AnchorSelector, or the standard TextQuoteSelector that repeats the anchor's plain quote for tools that do not know ours (spec/18 §18.3).",
+      "oneOf": [
+        {
+          "type": "object",
+          "properties": {
+            "type": {
+              "const": "AnchorSelector"
+            },
+            "anchor": {
+              "$ref": "anchor.schema.json"
+            }
+          },
+          "required": [
+            "type",
+            "anchor"
+          ],
+          "additionalProperties": false
+        },
+        {
+          "type": "object",
+          "properties": {
+            "type": {
+              "const": "TextQuoteSelector"
+            },
+            "exact": {
+              "type": "string",
+              "minLength": 1
+            },
+            "prefix": {
+              "type": "string"
+            },
+            "suffix": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "type",
+            "exact"
+          ],
+          "additionalProperties": false
+        }
+      ]
     }
   },
   "type": "object",
@@ -423,6 +467,79 @@
           ],
           "additionalProperties": false
         },
+        {
+          "type": "object",
+          "properties": {
+            "type": {
+              "const": "SpecificResource"
+            },
+            "kind": {
+              "const": "trace"
+            },
+            "source": {
+              "description": "The cited document, as a target's source names a document.",
+              "type": "string",
+              "pattern": "^tag:scient\\.ing,2026:doc:[a-z0-9][a-z0-9._-]*/[a-z][a-z0-9]*-[0-9a-hjkmnp-tv-z]{4,51}(\\.[a-z0-9][a-z0-9-]*)*$"
+            },
+            "selector": {
+              "description": "The passage of the cited document: an AnchorSelector, then a TextQuoteSelector when the anchor's quote is plain.",
+              "type": "array",
+              "items": {
+                "$ref": "#/$defs/selector"
+              },
+              "minItems": 1
+            },
+            "reference": {
+              "description": "The reference node of the citing document that the target's sentence cites and the trace is about.",
+              "$ref": "common.schema.json#/$defs/nodeId"
+            },
+            "note": {
+              "type": "string",
+              "minLength": 1
+            },
+            "verdict": {
+              "enum": [
+                "supports",
+                "partly",
+                "does-not",
+                "cannot-tell"
+              ]
+            },
+            "proposer": {
+              "description": "The tool that proposed the trace, required when the annotation's creator is Software (spec/18 §18.4).",
+              "type": "object",
+              "properties": {
+                "model": {
+                  "$ref": "common.schema.json#/$defs/model"
+                },
+                "run": {
+                  "type": "string",
+                  "minLength": 1
+                },
+                "score": {
+                  "$ref": "common.schema.json#/$defs/decimal"
+                },
+                "rank": {
+                  "type": "integer",
+                  "minimum": 1
+                }
+              },
+              "required": [
+                "model",
+                "run"
+              ],
+              "additionalProperties": false
+            }
+          },
+          "required": [
+            "type",
+            "kind",
+            "source",
+            "selector",
+            "reference"
+          ],
+          "additionalProperties": false
+        },
         {
           "type": "object",
           "properties": {
@@ -764,6 +881,46 @@
           "receipt"
         ]
       }
+    },
+    {
+      "description": "A tool's trace names the tool and the run that proposed it (spec/18 §18.4).",
+      "if": {
+        "properties": {
+          "creator": {
+            "properties": {
+              "type": {
+                "const": "Software"
+              }
+            },
+            "required": [
+              "type"
+            ]
+          },
+          "body": {
+            "properties": {
+              "kind": {
+                "const": "trace"
+              }
+            },
+            "required": [
+              "kind"
+            ]
+          }
+        },
+        "required": [
+          "creator",
+          "body"
+        ]
+      },
+      "then": {
+        "properties": {
+          "body": {
+            "required": [
+              "proposer"
+            ]
+          }
+        }
+      }
     }
   ]
 }