docs(db): note deferred date-format validation (#11) at the Date field arm

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

crates/db/Cargo.toml

@@ -15,3 +15,4 @@ serde_json.workspace = true
 [dev-dependencies]
 tokio.workspace = true
 time.workspace = true
+serde_json.workspace = true

crates/db/migrations/0005_object_fields.sql

@@ -0,0 +1,2 @@
+-- Flexible field values for a catalogue object, keyed by field-definition key.
+ALTER TABLE object ADD COLUMN fields JSONB NOT NULL DEFAULT '{}'::jsonb;

crates/db/src/catalog.rs

@@ -2,20 +2,20 @@
 //! on the caller's connection, so the change and its audit entry commit together.
 
 use domain::{
-    AuditAction, AuditActor, CatalogueObject, FieldChange, NewAuditEvent, ObjectId, ObjectInput,
-    Visibility,
+    AuditAction, AuditActor, CatalogueObject, FieldChange, FieldType, NewAuditEvent, ObjectId,
+    ObjectInput, Visibility,
 };
 use serde_json::{Value, json};
 use sqlx::Row;
 
-use crate::audit;
+use crate::{audit, authority, fields, vocab};
 
 /// The entity_type recorded in the audit log for catalogue objects.
 const ENTITY_TYPE: &str = "object";
 
 const OBJECT_COLUMNS: &str = "id, object_number, object_name, number_of_objects, \
      brief_description, current_location, current_owner, recorder, recording_date, \
-     visibility, created_at, updated_at";
+     visibility, fields, created_at, updated_at";
 
 /// Create an object and record a `created` audit entry, both on `conn`
 /// (pass a transaction connection `&mut *tx` so they commit atomically).
@@ -110,6 +110,7 @@ fn map_object(row: sqlx::postgres::PgRow) -> Result<CatalogueObject, sqlx::Error
         recorder: row.try_get("recorder")?,
         recording_date: row.try_get("recording_date")?,
         visibility,
+        fields: row.try_get("fields")?,
         created_at: row.try_get("created_at")?,
         updated_at: row.try_get("updated_at")?,
     })
@@ -259,3 +260,189 @@ pub async fn delete_object(
 
     Ok(true)
 }
+
+/// Why setting flexible field values failed.
+#[derive(Debug, thiserror::Error)]
+pub enum FieldError {
+    #[error("object not found")]
+    ObjectNotFound,
+    #[error("unknown field: {0}")]
+    UnknownField(String),
+    #[error("field `{field}` expects a {expected} value")]
+    TypeMismatch {
+        field: String,
+        expected: &'static str,
+    },
+    #[error("field `{field}`: value does not resolve to an existing {kind}")]
+    Unresolved { field: String, kind: &'static str },
+    #[error(transparent)]
+    Db(#[from] sqlx::Error),
+}
+
+/// Replace an object's flexible field values, validating each against the registry
+/// (type + term/authority resolution), and audit the per-field diff — all on `conn`.
+/// A no-op (identical to the current values) writes nothing and records no audit.
+///
+/// **Replace semantics:** `values` is the *complete* desired set. Omitting a key that
+/// was previously set REMOVES it (recorded in the audit as a removal); send every key
+/// the caller wants to retain.
+///
+/// Required-field *completeness* is intentionally NOT enforced here — a caller may set
+/// any subset. That check belongs to the publish gate (when moving to
+/// `Visibility::Public`, Plan 7).
+pub async fn set_object_fields(
+    conn: &mut sqlx::PgConnection,
+    actor: AuditActor,
+    object_id: ObjectId,
+    values: &serde_json::Map<String, Value>,
+) -> Result<(), FieldError> {
+    let Some(old) = object_by_id(&mut *conn, object_id).await? else {
+        return Err(FieldError::ObjectNotFound);
+    };
+
+    for (key, value) in values {
+        validate_field(&mut *conn, key, value).await?;
+    }
+
+    let new_fields = Value::Object(values.clone());
+    let changes = field_map_changes(&old.fields, &new_fields);
+
+    if changes.is_empty() {
+        return Ok(());
+    }
+
+    sqlx::query("UPDATE object SET fields = $2, updated_at = now() WHERE id = $1")
+        .bind(object_id.to_uuid())
+        .bind(&new_fields)
+        .execute(&mut *conn)
+        .await?;
+
+    audit::record(
+        &mut *conn,
+        &NewAuditEvent {
+            actor,
+            action: AuditAction::Updated,
+            entity_type: ENTITY_TYPE.to_owned(),
+            entity_id: object_id.to_uuid(),
+            changes,
+        },
+    )
+    .await?;
+
+    Ok(())
+}
+
+async fn validate_field(
+    conn: &mut sqlx::PgConnection,
+    key: &str,
+    value: &Value,
+) -> Result<(), FieldError> {
+    let def = fields::field_definition_by_key(&mut *conn, key)
+        .await?
+        .ok_or_else(|| FieldError::UnknownField(key.to_owned()))?;
+
+    match def.field_type {
+        FieldType::Text => require(value.is_string(), key, "text")?,
+        FieldType::LocalizedText => require(
+            value
+                .as_object()
+                .is_some_and(|o| o.values().all(Value::is_string)),
+            key,
+            "localized-text object {lang: string}",
+        )?,
+        FieldType::Integer => require(value.is_i64(), key, "integer")?,
+        // Format/range validation (real date parsing) is deferred to issue #11;
+        // here a date field only requires a string value.
+        FieldType::Date => require(value.is_string(), key, "date string")?,
+        FieldType::Boolean => require(value.is_boolean(), key, "boolean")?,
+        FieldType::Term { vocabulary_id } => {
+            let term_id = parse_uuid(value, key, "term id (uuid string)")?;
+
+            if vocab::resolve_term(
+                &mut *conn,
+                vocabulary_id,
+                domain::TermId::from_uuid(term_id),
+            )
+            .await?
+            .is_none()
+            {
+                return Err(FieldError::Unresolved {
+                    field: key.to_owned(),
+                    kind: "term",
+                });
+            }
+        }
+        FieldType::Authority { kind } => {
+            let authority_id = parse_uuid(value, key, "authority id (uuid string)")?;
+
+            match authority::resolve_authority(
+                &mut *conn,
+                domain::AuthorityId::from_uuid(authority_id),
+            )
+            .await?
+            {
+                Some(ref_) if kind.is_none_or(|k| ref_.kind() == k) => {}
+                _ => {
+                    return Err(FieldError::Unresolved {
+                        field: key.to_owned(),
+                        kind: "authority",
+                    });
+                }
+            }
+        }
+    }
+
+    Ok(())
+}
+
+fn require(ok: bool, field: &str, expected: &'static str) -> Result<(), FieldError> {
+    if ok {
+        Ok(())
+    } else {
+        Err(FieldError::TypeMismatch {
+            field: field.to_owned(),
+            expected,
+        })
+    }
+}
+
+fn parse_uuid(
+    value: &Value,
+    field: &str,
+    expected: &'static str,
+) -> Result<uuid::Uuid, FieldError> {
+    value
+        .as_str()
+        .and_then(|s| s.parse::<uuid::Uuid>().ok())
+        .ok_or_else(|| FieldError::TypeMismatch {
+            field: field.to_owned(),
+            expected,
+        })
+}
+
+/// Per-key diff between two flexible-field maps. `before`/`after` are `None` when
+/// the key is absent on that side (so adds and removes are captured).
+fn field_map_changes(old: &Value, new: &Value) -> Vec<FieldChange> {
+    let empty = serde_json::Map::new();
+    let old_map = old.as_object().unwrap_or(&empty);
+    let new_map = new.as_object().unwrap_or(&empty);
+
+    let keys: std::collections::BTreeSet<&String> = old_map.keys().chain(new_map.keys()).collect();
+
+    keys.into_iter()
+        .filter_map(|key| {
+            let before = old_map.get(key).cloned();
+            let after = new_map.get(key).cloned();
+
+            if before != after {
+                Some(FieldChange {
+                    field: key.clone(),
+                    before,
+                    after,
+                })
+            } else {
+                None
+            }
+        })
+        .collect()
+}

crates/db/tests/catalog.rs

@@ -116,3 +116,16 @@ async fn object_with_date_and_all_none_optionals_round_trips(pool: PgPool) {
             .any(|c| c.field == "recording_date")
     );
 }
+
+#[sqlx::test]
+async fn new_object_has_empty_fields(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let mut tx = db.pool().begin().await.unwrap();
+    let id = catalog::create_object(&mut tx, AuditActor::System, &sample_input("LM-9"))
+        .await
+        .unwrap();
+    tx.commit().await.unwrap();
+
+    let obj = catalog::object_by_id(db.pool(), id).await.unwrap().unwrap();
+    assert_eq!(obj.fields, serde_json::json!({}));
+}

crates/db/tests/migrate.rs

@@ -71,3 +71,16 @@ async fn migrate_creates_field_definition_tables(pool: PgPool) {
         );
     }
 }
+
+#[sqlx::test]
+async fn migrate_adds_object_fields_column(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let exists: Option<bool> = sqlx::query_scalar(
+        "SELECT true FROM information_schema.columns \
+         WHERE table_name = 'object' AND column_name = 'fields'",
+    )
+    .fetch_optional(db.pool())
+    .await
+    .unwrap();
+    assert_eq!(exists, Some(true));
+}

crates/db/tests/object_fields.rs

@@ -0,0 +1,374 @@
+use db::catalog::FieldError;
+use db::{Db, audit, catalog, fields, vocab};
+use domain::{
+    AuditAction, AuditActor, FieldType, LocalizedLabel, NewFieldDefinition, ObjectInput, Visibility,
+};
+use sqlx::PgPool;
+
+fn obj_input() -> ObjectInput {
+    ObjectInput {
+        object_number: "LM-1".into(),
+        object_name: "vase".into(),
+        number_of_objects: 1,
+        brief_description: None,
+        current_location: None,
+        current_owner: None,
+        recorder: None,
+        recording_date: None,
+        visibility: Visibility::Draft,
+    }
+}
+
+fn label(text: &str) -> Vec<LocalizedLabel> {
+    vec![LocalizedLabel {
+        lang: "en".into(),
+        label: text.into(),
+    }]
+}
+
+async fn setup_object(db: &Db) -> domain::ObjectId {
+    let mut tx = db.pool().begin().await.unwrap();
+    let id = catalog::create_object(&mut tx, AuditActor::System, &obj_input())
+        .await
+        .unwrap();
+    tx.commit().await.unwrap();
+    id
+}
+
+async fn define(db: &Db, key: &str, field_type: FieldType) {
+    let mut tx = db.pool().begin().await.unwrap();
+    fields::create_field_definition(
+        &mut tx,
+        &NewFieldDefinition {
+            key: key.into(),
+            field_type,
+            required: false,
+            group_key: None,
+            labels: label(key),
+        },
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+}
+
+#[sqlx::test]
+async fn sets_scalar_fields_and_audits(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(&db, "comments", FieldType::Text).await;
+    define(&db, "year", FieldType::Integer).await;
+    define(&db, "on_display", FieldType::Boolean).await;
+
+    let values = serde_json::json!({ "comments": "nice", "year": 1850, "on_display": true });
+
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, values.as_object().unwrap())
+        .await
+        .unwrap();
+    tx.commit().await.unwrap();
+
+    let obj = catalog::object_by_id(db.pool(), id).await.unwrap().unwrap();
+    assert_eq!(obj.fields["comments"], "nice");
+    assert_eq!(obj.fields["year"], 1850);
+    assert_eq!(obj.fields["on_display"], true);
+
+    let history = audit::history_for(db.pool(), "object", id.to_uuid())
+        .await
+        .unwrap();
+    assert_eq!(history.last().unwrap().action, AuditAction::Updated);
+    let changed: Vec<&str> = history
+        .last()
+        .unwrap()
+        .changes
+        .iter()
+        .map(|c| c.field.as_str())
+        .collect();
+    assert!(
+        changed.contains(&"comments")
+            && changed.contains(&"year")
+            && changed.contains(&"on_display")
+    );
+}
+
+#[sqlx::test]
+async fn term_field_must_resolve_in_its_vocabulary(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    let material = vocab::create_vocabulary(db.pool(), "material")
+        .await
+        .unwrap();
+    define(
+        &db,
+        "material",
+        FieldType::Term {
+            vocabulary_id: material.id,
+        },
+    )
+    .await;
+
+    let mut tx = db.pool().begin().await.unwrap();
+    let wood = vocab::add_term(
+        &mut tx,
+        &domain::NewTerm {
+            vocabulary_id: material.id,
+            external_uri: None,
+            labels: label("wood"),
+        },
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+
+    let ok = serde_json::json!({ "material": wood.to_string() });
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, ok.as_object().unwrap())
+        .await
+        .unwrap();
+    tx.commit().await.unwrap();
+
+    let bad = serde_json::json!({ "material": domain::TermId::new().to_string() });
+    let mut tx = db.pool().begin().await.unwrap();
+    let err =
+        catalog::set_object_fields(&mut tx, AuditActor::System, id, bad.as_object().unwrap()).await;
+    assert!(matches!(err, Err(FieldError::Unresolved { .. })));
+}
+
+#[sqlx::test]
+async fn unknown_field_and_type_mismatch_are_rejected(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(&db, "year", FieldType::Integer).await;
+
+    let unknown = serde_json::json!({ "nope": "x" });
+    let mut tx = db.pool().begin().await.unwrap();
+    assert!(matches!(
+        catalog::set_object_fields(
+            &mut tx,
+            AuditActor::System,
+            id,
+            unknown.as_object().unwrap()
+        )
+        .await,
+        Err(FieldError::UnknownField(_))
+    ));
+    drop(tx);
+
+    let wrong = serde_json::json!({ "year": "not a number" });
+    let mut tx = db.pool().begin().await.unwrap();
+    assert!(matches!(
+        catalog::set_object_fields(&mut tx, AuditActor::System, id, wrong.as_object().unwrap())
+            .await,
+        Err(FieldError::TypeMismatch { .. })
+    ));
+    drop(tx);
+}
+
+#[sqlx::test]
+async fn authority_field_enforces_kind(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(
+        &db,
+        "maker",
+        FieldType::Authority {
+            kind: Some(domain::AuthorityKind::Person),
+        },
+    )
+    .await;
+
+    let mut tx = db.pool().begin().await.unwrap();
+    let person = db::authority::create_authority(
+        &mut tx,
+        &domain::NewAuthority {
+            kind: domain::AuthorityKind::Person,
+            external_uri: None,
+            labels: label("Carl"),
+        },
+    )
+    .await
+    .unwrap();
+    let place = db::authority::create_authority(
+        &mut tx,
+        &domain::NewAuthority {
+            kind: domain::AuthorityKind::Place,
+            external_uri: None,
+            labels: label("Stockholm"),
+        },
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+
+    let ok = serde_json::json!({ "maker": person.to_string() });
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, ok.as_object().unwrap())
+        .await
+        .unwrap();
+    tx.commit().await.unwrap();
+
+    let bad = serde_json::json!({ "maker": place.to_string() });
+    let mut tx = db.pool().begin().await.unwrap();
+    assert!(matches!(
+        catalog::set_object_fields(&mut tx, AuditActor::System, id, bad.as_object().unwrap()).await,
+        Err(FieldError::Unresolved { .. })
+    ));
+}
+
+#[sqlx::test]
+async fn term_from_wrong_vocabulary_is_rejected(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    let material = vocab::create_vocabulary(db.pool(), "material")
+        .await
+        .unwrap();
+    let technique = vocab::create_vocabulary(db.pool(), "technique")
+        .await
+        .unwrap();
+    define(
+        &db,
+        "material",
+        FieldType::Term {
+            vocabulary_id: material.id,
+        },
+    )
+    .await;
+
+    // a real term, but in the WRONG vocabulary
+    let mut tx = db.pool().begin().await.unwrap();
+    let other = vocab::add_term(
+        &mut tx,
+        &domain::NewTerm {
+            vocabulary_id: technique.id,
+            external_uri: None,
+            labels: label("forged"),
+        },
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+
+    let bad = serde_json::json!({ "material": other.to_string() });
+    let mut tx = db.pool().begin().await.unwrap();
+    assert!(matches!(
+        catalog::set_object_fields(&mut tx, AuditActor::System, id, bad.as_object().unwrap()).await,
+        Err(FieldError::Unresolved { .. })
+    ));
+}
+
+#[sqlx::test]
+async fn localized_text_round_trips(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(&db, "title", FieldType::LocalizedText).await;
+
+    let values = serde_json::json!({ "title": { "sv": "Vas", "en": "Vase" } });
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, values.as_object().unwrap())
+        .await
+        .unwrap();
+    tx.commit().await.unwrap();
+
+    let obj = catalog::object_by_id(db.pool(), id).await.unwrap().unwrap();
+    assert_eq!(obj.fields["title"]["sv"], "Vas");
+    assert_eq!(obj.fields["title"]["en"], "Vase");
+
+    let bad = serde_json::json!({ "title": { "sv": 5 } });
+    let mut tx = db.pool().begin().await.unwrap();
+    assert!(matches!(
+        catalog::set_object_fields(&mut tx, AuditActor::System, id, bad.as_object().unwrap()).await,
+        Err(FieldError::TypeMismatch { .. })
+    ));
+}
+
+#[sqlx::test]
+async fn replace_semantics_remove_a_field_and_audit_it(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(&db, "comments", FieldType::Text).await;
+    define(&db, "year", FieldType::Integer).await;
+
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(
+        &mut tx,
+        AuditActor::System,
+        id,
+        serde_json::json!({ "comments": "x", "year": 1850 })
+            .as_object()
+            .unwrap(),
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(
+        &mut tx,
+        AuditActor::System,
+        id,
+        serde_json::json!({ "comments": "x" }).as_object().unwrap(),
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+
+    let obj = catalog::object_by_id(db.pool(), id).await.unwrap().unwrap();
+    assert!(obj.fields.get("year").is_none());
+
+    let history = audit::history_for(db.pool(), "object", id.to_uuid())
+        .await
+        .unwrap();
+    let last = history.last().unwrap();
+    let year = last
+        .changes
+        .iter()
+        .find(|c| c.field == "year")
+        .expect("year removal recorded");
+    assert!(year.before.is_some());
+    assert!(year.after.is_none());
+}
+
+#[sqlx::test]
+async fn no_op_set_records_no_audit(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(&db, "comments", FieldType::Text).await;
+
+    let values = serde_json::json!({ "comments": "x" });
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, values.as_object().unwrap())
+        .await
+        .unwrap();
+    tx.commit().await.unwrap();
+
+    let before = audit::history_for(db.pool(), "object", id.to_uuid())
+        .await
+        .unwrap()
+        .len();
+
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, values.as_object().unwrap())
+        .await
+        .unwrap();
+    tx.commit().await.unwrap();
+
+    let after = audit::history_for(db.pool(), "object", id.to_uuid())
+        .await
+        .unwrap()
+        .len();
+    assert_eq!(before, after, "a no-op set must not add an audit entry");
+}
+
+#[sqlx::test]
+async fn set_on_missing_object_errors(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let mut tx = db.pool().begin().await.unwrap();
+    let err = catalog::set_object_fields(
+        &mut tx,
+        AuditActor::System,
+        domain::ObjectId::new(),
+        serde_json::json!({}).as_object().unwrap(),
+    )
+    .await;
+    assert!(matches!(err, Err(FieldError::ObjectNotFound)));
+}

crates/domain/src/object.rs

@@ -62,6 +62,8 @@ pub struct CatalogueObject {
     pub recorder: Option<String>,
     pub recording_date: Option<Date>,
     pub visibility: Visibility,
+    /// Flexible field values (field key -> value), validated against the registry.
+    pub fields: serde_json::Value,
     pub created_at: OffsetDateTime,
     pub updated_at: OffsetDateTime,
 }

docs/plans/2026-06-02-object-flexible-fields.md

@@ -0,0 +1,584 @@
+# Object Flexible-Field Values Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Where the registry gets used — a `fields jsonb` column on `object`, with `set_object_fields` that validates each value against the field-definition registry (Plan 4) + resolves term/authority references (Plan 2) + audits the per-field changes (Plan 1/3), all in the write transaction.
+
+**Architecture:** `CatalogueObject` gains a `fields: serde_json::Value` (the raw JSONB map). `db::catalog::set_object_fields` takes the complete desired field map, validates every value (unknown key → error; type mismatch → error; term/authority must resolve), **replaces** the JSONB, and audits the diff against the old map. A typed `FieldError` (using the `db` crate's so-far-unused `thiserror` dep) surfaces validation failures. Required-field *completeness* is NOT enforced here (deferred to the publish gate, Plan 7).
+
+**Tech Stack:** Rust 2024, sqlx 0.8 (`json`), `serde_json` (values + validation), `thiserror` (FieldError). Tests use `#[sqlx::test]`.
+
+## Design decisions (approved)
+- Storage: `object.fields jsonb NOT NULL DEFAULT '{}'`, `field_key → value`.
+- Value shapes: text→string, localized_text→`{lang: string}`, integer→JSON integer, date→string, boolean→bool, term→term-UUID string (resolves in bound vocab), authority→authority-UUID string (resolves; kind matches if constrained).
+- `set_object_fields` = **replace** the whole map, **separate** from `update_object`; audits the diff; no-op skips write+audit (consistent with `update_object`).
+- Required-field enforcement deferred to publish (Plan 7).
+- Strict per-field rules (date format, min/max, regex) deferred to #11; here `date` validates as a string only.
+- Spectrum field-set seeding is a separate follow-on (not this plan).
+
+## Prerequisites
+- Postgres for tests with CREATE DATABASE rights; pass `DATABASE_URL` inline. Shell env does not persist between commands. Pass transaction connections as `&mut tx` (NOT `&mut *tx`) to avoid clippy `explicit_auto_deref`.
+
+## File Structure
+```
+crates/domain/src/object.rs   CatalogueObject gains `fields: serde_json::Value`
+crates/db/
+  Cargo.toml                  serde_json also in [dev-dependencies]
+  migrations/0005_object_fields.sql
+  src/catalog.rs              + fields in SELECT/map; FieldError; set_object_fields + validation helpers
+  tests/object_fields.rs
+```
+
+---
+
+## Task 1: `fields` column + read it back
+
+**Files:** create `crates/db/migrations/0005_object_fields.sql`; modify `crates/domain/src/object.rs`, `crates/db/src/catalog.rs`, `crates/db/tests/migrate.rs`, `crates/db/Cargo.toml`.
+
+- [ ] **Step 1: Migration.** Create `crates/db/migrations/0005_object_fields.sql`:
+```sql
+-- Flexible field values for a catalogue object, keyed by field-definition key.
+ALTER TABLE object ADD COLUMN fields JSONB NOT NULL DEFAULT '{}'::jsonb;
+```
+
+- [ ] **Step 2: Domain.** In `crates/domain/src/object.rs`, add a `fields` field to `CatalogueObject` (after `visibility`, before the timestamps):
+```rust
+    pub visibility: Visibility,
+    /// Flexible field values (field key -> value), validated against the registry.
+    pub fields: serde_json::Value,
+    pub created_at: OffsetDateTime,
+    pub updated_at: OffsetDateTime,
+```
+Add `use serde_json` if needed (serde_json is already a domain dependency). `CatalogueObject` derives `Debug, Clone, PartialEq` (NOT `Eq`) — `serde_json::Value` is `PartialEq` but not `Eq`, so do not add `Eq`. `to_input()` is unchanged (it maps only the 9 core mutable fields; `fields` is not part of `ObjectInput`).
+
+- [ ] **Step 3: db reads the column.** In `crates/db/src/catalog.rs`:
+  - Add `fields` to the `OBJECT_COLUMNS` const (append `, fields`).
+  - In `map_object`, add: `fields: row.try_get("fields")?,` (between `visibility` and `created_at`). `sqlx` decodes a `jsonb` column directly into `serde_json::Value`.
+  (`create_object`'s INSERT does NOT list `fields`, so it uses the `'{}'` default — leave the INSERT unchanged.)
+
+- [ ] **Step 4: dev-dep.** In `crates/db/Cargo.toml`, add `serde_json` to `[dev-dependencies]` (it is a normal dep, but integration tests need it in scope):
+```toml
+[dev-dependencies]
+tokio.workspace = true
+time.workspace = true
+serde_json.workspace = true
+```
+
+- [ ] **Step 5: Tests.** Append to `crates/db/tests/migrate.rs`:
+```rust
+#[sqlx::test]
+async fn migrate_adds_object_fields_column(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let exists: Option<bool> = sqlx::query_scalar(
+        "SELECT true FROM information_schema.columns \
+         WHERE table_name = 'object' AND column_name = 'fields'",
+    )
+    .fetch_optional(db.pool())
+    .await
+    .unwrap();
+    assert_eq!(exists, Some(true));
+}
+```
+And append to `crates/db/tests/catalog.rs`:
+```rust
+#[sqlx::test]
+async fn new_object_has_empty_fields(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let mut tx = db.pool().begin().await.unwrap();
+    let id = catalog::create_object(&mut tx, AuditActor::System, &sample_input("LM-9")).await.unwrap();
+    tx.commit().await.unwrap();
+
+    let obj = catalog::object_by_id(db.pool(), id).await.unwrap().unwrap();
+    assert_eq!(obj.fields, serde_json::json!({}));
+}
+```
+(`crates/db/tests/catalog.rs` already imports what it needs except possibly `serde_json` — add `use serde_json` if the test uses the `json!` macro and it is not already imported; `serde_json::json!` works fully-qualified as written.)
+
+- [ ] **Step 6: Run + lint.** `DATABASE_URL=<url> cargo test -p db --test migrate --test catalog` and `cargo test -p domain` → all pass. `cargo +nightly fmt`; `DATABASE_URL=<url> cargo clippy -p db -p domain --all-targets -- -D warnings` → clean.
+
+- [ ] **Step 7: Commit.**
+```bash
+git add crates/domain crates/db
+git commit -m "feat(db): add object.fields jsonb column, read it into CatalogueObject"
+```
+
+---
+
+## Task 2: `set_object_fields` — validate, write, audit
+
+**Files:** modify `crates/db/src/catalog.rs`; create `crates/db/tests/object_fields.rs`.
+
+- [ ] **Step 1: Write the failing test** `crates/db/tests/object_fields.rs`:
+```rust
+use db::catalog::FieldError;
+use db::{Db, audit, catalog, fields, vocab};
+use domain::{
+    AuditAction, AuditActor, FieldType, LocalizedLabel, NewFieldDefinition, ObjectInput, Visibility,
+};
+use sqlx::PgPool;
+
+fn obj_input() -> ObjectInput {
+    ObjectInput {
+        object_number: "LM-1".into(),
+        object_name: "vase".into(),
+        number_of_objects: 1,
+        brief_description: None,
+        current_location: None,
+        current_owner: None,
+        recorder: None,
+        recording_date: None,
+        visibility: Visibility::Draft,
+    }
+}
+
+fn label(text: &str) -> Vec<LocalizedLabel> {
+    vec![LocalizedLabel { lang: "en".into(), label: text.into() }]
+}
+
+async fn setup_object(db: &Db) -> domain::ObjectId {
+    let mut tx = db.pool().begin().await.unwrap();
+    let id = catalog::create_object(&mut tx, AuditActor::System, &obj_input()).await.unwrap();
+    tx.commit().await.unwrap();
+    id
+}
+
+async fn define(db: &Db, key: &str, field_type: FieldType) {
+    let mut tx = db.pool().begin().await.unwrap();
+    fields::create_field_definition(
+        &mut tx,
+        &NewFieldDefinition { key: key.into(), field_type, required: false, group_key: None, labels: label(key) },
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+}
+
+#[sqlx::test]
+async fn sets_scalar_fields_and_audits(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(&db, "comments", FieldType::Text).await;
+    define(&db, "year", FieldType::Integer).await;
+    define(&db, "on_display", FieldType::Boolean).await;
+
+    let values = serde_json::json!({ "comments": "nice", "year": 1850, "on_display": true });
+
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, values.as_object().unwrap())
+        .await
+        .unwrap();
+    tx.commit().await.unwrap();
+
+    let obj = catalog::object_by_id(db.pool(), id).await.unwrap().unwrap();
+    assert_eq!(obj.fields["comments"], "nice");
+    assert_eq!(obj.fields["year"], 1850);
+    assert_eq!(obj.fields["on_display"], true);
+
+    let history = audit::history_for(db.pool(), "object", id.to_uuid()).await.unwrap();
+    // created + the field set
+    assert_eq!(history.last().unwrap().action, AuditAction::Updated);
+    let changed: Vec<&str> = history.last().unwrap().changes.iter().map(|c| c.field.as_str()).collect();
+    assert!(changed.contains(&"comments") && changed.contains(&"year") && changed.contains(&"on_display"));
+}
+
+#[sqlx::test]
+async fn term_field_must_resolve_in_its_vocabulary(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    let material = vocab::create_vocabulary(db.pool(), "material").await.unwrap();
+    define(&db, "material", FieldType::Term { vocabulary_id: material.id }).await;
+
+    // add a real term
+    let mut tx = db.pool().begin().await.unwrap();
+    let wood = vocab::add_term(
+        &mut tx,
+        &domain::NewTerm { vocabulary_id: material.id, external_uri: None, labels: label("wood") },
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+
+    // valid term id resolves
+    let ok = serde_json::json!({ "material": wood.to_string() });
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, ok.as_object().unwrap()).await.unwrap();
+    tx.commit().await.unwrap();
+
+    // random uuid does not resolve
+    let bad = serde_json::json!({ "material": domain::TermId::new().to_string() });
+    let mut tx = db.pool().begin().await.unwrap();
+    let err = catalog::set_object_fields(&mut tx, AuditActor::System, id, bad.as_object().unwrap()).await;
+    assert!(matches!(err, Err(FieldError::Unresolved { .. })));
+}
+
+#[sqlx::test]
+async fn unknown_field_and_type_mismatch_are_rejected(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(&db, "year", FieldType::Integer).await;
+
+    let unknown = serde_json::json!({ "nope": "x" });
+    let mut tx = db.pool().begin().await.unwrap();
+    assert!(matches!(
+        catalog::set_object_fields(&mut tx, AuditActor::System, id, unknown.as_object().unwrap()).await,
+        Err(FieldError::UnknownField(_))
+    ));
+    drop(tx);
+
+    let wrong = serde_json::json!({ "year": "not a number" });
+    let mut tx = db.pool().begin().await.unwrap();
+    assert!(matches!(
+        catalog::set_object_fields(&mut tx, AuditActor::System, id, wrong.as_object().unwrap()).await,
+        Err(FieldError::TypeMismatch { .. })
+    ));
+}
+```
+
+- [ ] **Step 2: Run to verify it fails.** `DATABASE_URL=<url> cargo test -p db --test object_fields` → FAIL.
+
+- [ ] **Step 3: Implement** — add to the top of `crates/db/src/catalog.rs` the `FieldError` type, and append the function + helpers. Add imports as needed (`use crate::{audit, authority, fields, vocab};` — `audit` is already imported; add `authority, fields, vocab`). Also ensure `use domain::{... TermId, AuthorityId ...}` are available (add to the existing domain import).
+
+`FieldError`:
+```rust
+/// Why setting flexible field values failed.
+#[derive(Debug, thiserror::Error)]
+pub enum FieldError {
+    #[error("object not found")]
+    ObjectNotFound,
+    #[error("unknown field: {0}")]
+    UnknownField(String),
+    #[error("field `{field}` expects a {expected} value")]
+    TypeMismatch { field: String, expected: &'static str },
+    #[error("field `{field}`: value does not resolve to an existing {kind}")]
+    Unresolved { field: String, kind: &'static str },
+    #[error(transparent)]
+    Db(#[from] sqlx::Error),
+}
+```
+
+`set_object_fields` + helpers:
+```rust
+/// Replace an object's flexible field values, validating each against the registry
+/// (type + term/authority resolution), and audit the per-field diff — all on `conn`.
+/// A no-op (identical to the current values) writes nothing and records no audit.
+pub async fn set_object_fields(
+    conn: &mut sqlx::PgConnection,
+    actor: AuditActor,
+    object_id: ObjectId,
+    values: &serde_json::Map<String, Value>,
+) -> Result<(), FieldError> {
+    let Some(old) = object_by_id(&mut *conn, object_id).await? else {
+        return Err(FieldError::ObjectNotFound);
+    };
+
+    for (key, value) in values {
+        validate_field(&mut *conn, key, value).await?;
+    }
+
+    let new_fields = Value::Object(values.clone());
+    let changes = field_map_changes(&old.fields, &new_fields);
+    if changes.is_empty() {
+        return Ok(());
+    }
+
+    sqlx::query("UPDATE object SET fields = $2, updated_at = now() WHERE id = $1")
+        .bind(object_id.to_uuid())
+        .bind(&new_fields)
+        .execute(&mut *conn)
+        .await?;
+
+    audit::record(
+        &mut *conn,
+        &NewAuditEvent {
+            actor,
+            action: AuditAction::Updated,
+            entity_type: ENTITY_TYPE.to_owned(),
+            entity_id: object_id.to_uuid(),
+            changes,
+        },
+    )
+    .await?;
+
+    Ok(())
+}
+
+async fn validate_field(
+    conn: &mut sqlx::PgConnection,
+    key: &str,
+    value: &Value,
+) -> Result<(), FieldError> {
+    let def = fields::field_definition_by_key(&mut *conn, key)
+        .await?
+        .ok_or_else(|| FieldError::UnknownField(key.to_owned()))?;
+
+    match def.field_type {
+        FieldType::Text => require(value.is_string(), key, "text")?,
+        FieldType::LocalizedText => require(
+            value.as_object().is_some_and(|o| o.values().all(Value::is_string)),
+            key,
+            "localized-text object {lang: string}",
+        )?,
+        FieldType::Integer => require(value.is_i64(), key, "integer")?,
+        FieldType::Date => require(value.is_string(), key, "date string")?,
+        FieldType::Boolean => require(value.is_boolean(), key, "boolean")?,
+        FieldType::Term { vocabulary_id } => {
+            let term_id = parse_uuid(value, key, "term id (uuid string)")?;
+            if vocab::resolve_term(&mut *conn, vocabulary_id, domain::TermId::from_uuid(term_id))
+                .await?
+                .is_none()
+            {
+                return Err(FieldError::Unresolved { field: key.to_owned(), kind: "term" });
+            }
+        }
+        FieldType::Authority { kind } => {
+            let authority_id = parse_uuid(value, key, "authority id (uuid string)")?;
+            match authority::resolve_authority(&mut *conn, domain::AuthorityId::from_uuid(authority_id)).await? {
+                Some(r) if kind.is_none_or(|k| r.kind() == k) => {}
+                _ => return Err(FieldError::Unresolved { field: key.to_owned(), kind: "authority" }),
+            }
+        }
+    }
+    Ok(())
+}
+
+fn require(ok: bool, field: &str, expected: &'static str) -> Result<(), FieldError> {
+    if ok {
+        Ok(())
+    } else {
+        Err(FieldError::TypeMismatch { field: field.to_owned(), expected })
+    }
+}
+
+fn parse_uuid(value: &Value, field: &str, expected: &'static str) -> Result<uuid::Uuid, FieldError> {
+    value
+        .as_str()
+        .and_then(|s| s.parse::<uuid::Uuid>().ok())
+        .ok_or_else(|| FieldError::TypeMismatch { field: field.to_owned(), expected })
+}
+
+/// Per-key diff between two flexible-field maps. `before`/`after` are `None` when
+/// the key is absent on that side (so adds and removes are captured).
+fn field_map_changes(old: &Value, new: &Value) -> Vec<FieldChange> {
+    let empty = serde_json::Map::new();
+    let old_map = old.as_object().unwrap_or(&empty);
+    let new_map = new.as_object().unwrap_or(&empty);
+
+    let keys: std::collections::BTreeSet<&String> = old_map.keys().chain(new_map.keys()).collect();
+    keys.into_iter()
+        .filter_map(|key| {
+            let before = old_map.get(key).cloned();
+            let after = new_map.get(key).cloned();
+            if before != after {
+                Some(FieldChange { field: key.clone(), before, after })
+            } else {
+                None
+            }
+        })
+        .collect()
+}
+```
+Notes:
+- `db` already depends on `thiserror`, `uuid`, `serde_json`, `domain`, and has the `vocab`/`authority`/`fields`/`audit` sibling modules — no Cargo changes beyond Task 1's dev-dep.
+- `Value` and `FieldChange` are already imported at the top of `catalog.rs` (`use serde_json::{Value, json};` and `use domain::{..., FieldChange, ...}`). If `FieldChange` is not in the existing domain import, add it.
+
+- [ ] **Step 4: Run to verify it passes.** `DATABASE_URL=<url> cargo test -p db --test object_fields` → PASS (3 tests).
+
+- [ ] **Step 5: Lint.** `cargo +nightly fmt`; `DATABASE_URL=<url> cargo clippy -p db --all-targets -- -D warnings` → clean.
+
+- [ ] **Step 6: Commit.**
+```bash
+git add crates/db
+git commit -m "feat(db): set_object_fields with registry validation and audited diffs"
+```
+
+---
+
+## Task 3: validation coverage + replace/no-op semantics
+
+**Files:** modify `crates/db/tests/object_fields.rs`.
+
+- [ ] **Step 1: Add tests** to `crates/db/tests/object_fields.rs`:
+```rust
+#[sqlx::test]
+async fn authority_field_enforces_kind(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(&db, "maker", FieldType::Authority { kind: Some(domain::AuthorityKind::Person) }).await;
+
+    let mut tx = db.pool().begin().await.unwrap();
+    let person = db::authority::create_authority(
+        &mut tx,
+        &domain::NewAuthority {
+            kind: domain::AuthorityKind::Person,
+            external_uri: None,
+            labels: label("Carl"),
+        },
+    )
+    .await
+    .unwrap();
+    let place = db::authority::create_authority(
+        &mut tx,
+        &domain::NewAuthority {
+            kind: domain::AuthorityKind::Place,
+            external_uri: None,
+            labels: label("Stockholm"),
+        },
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+
+    // a person resolves
+    let ok = serde_json::json!({ "maker": person.to_string() });
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, ok.as_object().unwrap()).await.unwrap();
+    tx.commit().await.unwrap();
+
+    // a place is the wrong kind
+    let bad = serde_json::json!({ "maker": place.to_string() });
+    let mut tx = db.pool().begin().await.unwrap();
+    assert!(matches!(
+        catalog::set_object_fields(&mut tx, AuditActor::System, id, bad.as_object().unwrap()).await,
+        Err(FieldError::Unresolved { .. })
+    ));
+}
+
+#[sqlx::test]
+async fn localized_text_round_trips(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(&db, "title", FieldType::LocalizedText).await;
+
+    let values = serde_json::json!({ "title": { "sv": "Vas", "en": "Vase" } });
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, values.as_object().unwrap()).await.unwrap();
+    tx.commit().await.unwrap();
+
+    let obj = catalog::object_by_id(db.pool(), id).await.unwrap().unwrap();
+    assert_eq!(obj.fields["title"]["sv"], "Vas");
+    assert_eq!(obj.fields["title"]["en"], "Vase");
+
+    // a non-string member is rejected
+    let bad = serde_json::json!({ "title": { "sv": 5 } });
+    let mut tx = db.pool().begin().await.unwrap();
+    assert!(matches!(
+        catalog::set_object_fields(&mut tx, AuditActor::System, id, bad.as_object().unwrap()).await,
+        Err(FieldError::TypeMismatch { .. })
+    ));
+}
+
+#[sqlx::test]
+async fn replace_semantics_remove_a_field_and_audit_it(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(&db, "comments", FieldType::Text).await;
+    define(&db, "year", FieldType::Integer).await;
+
+    // set both
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(
+        &mut tx,
+        AuditActor::System,
+        id,
+        serde_json::json!({ "comments": "x", "year": 1850 }).as_object().unwrap(),
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+
+    // replace with only `comments` -> `year` removed
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(
+        &mut tx,
+        AuditActor::System,
+        id,
+        serde_json::json!({ "comments": "x" }).as_object().unwrap(),
+    )
+    .await
+    .unwrap();
+    tx.commit().await.unwrap();
+
+    let obj = catalog::object_by_id(db.pool(), id).await.unwrap().unwrap();
+    assert!(obj.fields.get("year").is_none());
+
+    let history = audit::history_for(db.pool(), "object", id.to_uuid()).await.unwrap();
+    let last = history.last().unwrap();
+    let year = last.changes.iter().find(|c| c.field == "year").expect("year removal recorded");
+    assert!(year.before.is_some());
+    assert!(year.after.is_none());
+}
+
+#[sqlx::test]
+async fn no_op_set_records_no_audit(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let id = setup_object(&db).await;
+    define(&db, "comments", FieldType::Text).await;
+
+    let values = serde_json::json!({ "comments": "x" });
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, values.as_object().unwrap()).await.unwrap();
+    tx.commit().await.unwrap();
+
+    let before = audit::history_for(db.pool(), "object", id.to_uuid()).await.unwrap().len();
+
+    // setting the identical map again is a no-op
+    let mut tx = db.pool().begin().await.unwrap();
+    catalog::set_object_fields(&mut tx, AuditActor::System, id, values.as_object().unwrap()).await.unwrap();
+    tx.commit().await.unwrap();
+
+    let after = audit::history_for(db.pool(), "object", id.to_uuid()).await.unwrap().len();
+    assert_eq!(before, after, "a no-op set must not add an audit entry");
+}
+
+#[sqlx::test]
+async fn set_on_missing_object_errors(pool: PgPool) {
+    let db = Db::from_pool(pool);
+    let mut tx = db.pool().begin().await.unwrap();
+    let err = catalog::set_object_fields(
+        &mut tx,
+        AuditActor::System,
+        domain::ObjectId::new(),
+        serde_json::json!({}).as_object().unwrap(),
+    )
+    .await;
+    assert!(matches!(err, Err(FieldError::ObjectNotFound)));
+}
+```
+
+- [ ] **Step 2: Run.** `DATABASE_URL=<url> cargo test -p db --test object_fields` → PASS (8 tests total).
+
+- [ ] **Step 3: Full workspace check.**
+```bash
+cargo +nightly fmt --check
+DATABASE_URL=<url> cargo clippy --workspace --all-targets -- -D warnings
+DATABASE_URL=<url> cargo test --workspace
+```
+Expected: all green.
+
+- [ ] **Step 4: Commit.**
+```bash
+git add crates/db
+git commit -m "test(db): cover authority-kind, localized text, replace/remove, no-op, missing object"
+```
+
+---
+
+## Self-Review (completed)
+
+**Spec coverage (§6.2 values + validation):**
+- `fields jsonb` on object; value shapes per type → Tasks 1–2. ✓
+- Validation against registry (type) + term/authority resolution → Task 2 `validate_field`. ✓
+- Replace semantics; audited per-field diffs (adds/removes/changes); no-op skip → Task 2 `set_object_fields`/`field_map_changes` + Task 3 tests. ✓
+- Required-completeness deferred to publish (Plan 7); strict date/format rules deferred to #11. ✓ (intentional)
+- Typed `FieldError` (uses the `db` crate's `thiserror`). ✓
+- SQL confined to `db`; `domain` I/O-free (only gains a `serde_json::Value` field). ✓
+
+**Placeholder scan:** none. `<url>` is the documented `DATABASE_URL`.
+
+**Type consistency:** `set_object_fields(&mut PgConnection, AuditActor, ObjectId, &serde_json::Map<String, Value>) -> Result<(), FieldError>` used identically across impl + all tests. `FieldError` variants matched in tests. `validate_field` matches on `FieldType` variants from `domain` (Plan 4); `vocab::resolve_term`/`authority::resolve_authority` signatures (Plan 2) used as defined. `field_map_changes` produces `FieldChange` (Plan 1) consumed by `audit::record`. `CatalogueObject.fields` added in Task 1 is read by `map_object` and asserted in tests.
+
+## Notes for follow-on plans
+- **Spectrum field-set seeding** (a follow-on): use `reference/spectrum-5.0-cataloguing-units-of-information.md` to seed `field_definition`s (key + type + vocabulary binding for "use a standard term source" fields, authority binding for "form of name" fields).
+- **Required-field completeness** is enforced at the publish gate (Plan 7): when moving to `Visibility::Public`, check all `required` field definitions have a value.
+- **Strict per-field validation rules** (date format, ranges, regex) — issue #11.
+- The API layer (Plan 7+/10) will call `update_object` (core) and `set_object_fields` (flexible) within one transaction for a single logical edit, yielding two audit entries; consider whether to coalesce.