refactor(storage, conversation): Store base config separately

crates/jp_conversation/src/compat.rs

@@ -1,70 +1,52 @@
-//! Backward-compatible deserialization for config deltas.
+//! Backward-compatible deserialization for [`PartialAppConfig`].
 //!
-//! When the `AppConfig` schema evolves (fields added, removed, or renamed), old
-//! conversation streams may contain `ConfigDelta` events referencing fields
-//! that no longer exist. The standard serde `deny_unknown_fields` on
-//! `Partial*Config` types causes deserialization to fail entirely.
+//! When the [`AppConfig`] schema evolves (fields added, removed, or renamed),
+//! old conversation data may reference fields that no longer exist. The
+//! standard serde `deny_unknown_fields` on `Partial*Config` types causes
+//! deserialization to fail entirely.
 //!
-//! This module provides schema-aware stripping: before deserializing a config
-//! delta, we walk the JSON value alongside the current `AppConfig` schema and
-//! remove any keys that don't exist in the schema. If deserialization still
-//! fails after stripping (e.g. a field's type changed), we fall back to an
-//! empty delta preserving only the timestamp.
+//! This module provides schema-aware stripping: before deserializing, we walk
+//! the JSON value alongside the current `AppConfig` schema and remove any keys
+//! that don't exist in the schema. If deserialization still fails after
+//! stripping (e.g. a field's type changed), we fall back to an empty config.
 
-use chrono::Utc;
 use jp_config::{AppConfig, PartialAppConfig, Schema, SchemaType};
 use serde_json::Value;
 use tracing::warn;
 
-use crate::{parse_dt, stream::ConfigDelta};
-
-/// Deserialize a `ConfigDelta` from a raw JSON value, tolerating schema
-/// changes.
+/// Deserialize a [`PartialAppConfig`] from a raw JSON value, tolerating
+/// schema changes.
 ///
-/// 1. Strips unknown fields from the `delta` subtree using the current
-///    `AppConfig` schema.
+/// 1. Strips unknown fields using the current [`AppConfig`] schema.
 /// 2. Attempts typed deserialization.
-/// 3. If that fails (e.g. a type changed), falls back to an empty delta with
-///    just the timestamp preserved.
-pub fn deserialize_config_delta(mut value: Value) -> ConfigDelta {
+/// 3. If that fails (e.g. a field's type changed), falls back to
+///    [`PartialAppConfig::empty()`].
+///
+/// Used for both the base config snapshot (`base_config.json`) and config delta
+/// events in the event stream.
+pub fn deserialize_partial_config(mut value: Value) -> PartialAppConfig {
     let schema = AppConfig::schema();
 
-    if let Some(delta) = value.get_mut("delta") {
-        let stripped = strip_unknown_fields(delta, &schema);
-        if stripped > 0 {
-            warn!(
-                count = stripped,
-                "Stripped unknown fields from stored config delta.",
-            );
-        }
+    let stripped = strip_unknown_fields(&mut value, &schema);
+    if stripped > 0 {
+        warn!(
+            count = stripped,
+            "Stripped unknown fields from stored config.",
+        );
     }
 
-    match serde_json::from_value::<ConfigDelta>(value.clone()) {
-        Ok(delta) => delta,
+    match serde_json::from_value::<PartialAppConfig>(value) {
+        Ok(config) => config,
         Err(err) => {
             warn!(
                 error = %err,
-                "Config delta incompatible with current schema, replacing with empty delta.",
+                "Stored config incompatible with current schema, replacing with empty config.",
             );
-            fallback_config_delta(&value)
+            PartialAppConfig::empty()
         }
     }
 }
 
-/// Extract just the timestamp from the raw JSON and build an empty delta.
-fn fallback_config_delta(value: &Value) -> ConfigDelta {
-    let timestamp = value
-        .get("timestamp")
-        .and_then(|v| v.as_str())
-        .and_then(|s| parse_dt(s).ok())
-        .unwrap_or_else(Utc::now);
-
-    ConfigDelta {
-        timestamp,
-        delta: Box::new(PartialAppConfig::empty()),
-    }
-}
-
 /// Recursively strip JSON object keys that don't exist in the schema.
 ///
 /// At each [`SchemaType::Struct`] level, retains only keys present in the
@@ -79,7 +61,7 @@ fn fallback_config_delta(value: &Value) -> ConfigDelta {
 ///
 /// [`flatten`]: jp_config::schema::SchemaField::flatten
 fn strip_unknown_fields(value: &mut Value, schema: &Schema) -> usize {
-    let SchemaType::Struct(ref struct_type) = schema.ty else {
+    let SchemaType::Struct(struct_type) = &schema.ty else {
         return 0;
     };