docs: make target.loadedFromSource canonical, drop context mirror

reference/resources/resource-api.md

@@ -250,21 +250,23 @@ Harper automatically serializes concurrent requests for the same missing or stal
 
 #### Observing cache disposition
 
-Each `get` on a caching table records whether the record came from the cache or from the source, in the `loadedFromSource` property of both the request context and the `RequestTarget`:
+Whether a `get` on a caching table was served from cache or loaded from the source is a **per-`get` result**, recorded on the `RequestTarget` for that call as `target.loadedFromSource`. Because each `get()` has its own target, the value is precise to that one call and unaffected by any nested or subsequent gets — it is what Harper's REST handler reads to set cache response headers.
 
 ```javascript
-const context = {};
-const record = await MyCache.get(recordId, context);
-console.log(context.loadedFromSource); // true = went to the source, false = served from cache
+import { RequestTarget } from 'harper';
+
+const target = new RequestTarget();
+target.id = recordId;
+const record = await MyCache.get(target);
+console.log(target.loadedFromSource); // true = loaded from source, false = served from cache
 ```
 
-Within a resource method, the same value is available on the active context via `getContext().loadedFromSource` after the `get` resolves. The flag settles as follows:
+The flag settles as follows:
 
 - `true` — the get went to the source: either it fetched the record, or the source errored and a stale cached record was served as a fallback (`staleIfError`). `true` means a source request was made, not necessarily that the returned data is fresh.
 - `false` — the record was served from the cache: fresh hits, `onlyIfCached` requests, stale-while-revalidate responses (the source fetch continues in the background), and requests that waited on another request's in-flight fetch of the same record. This last case means a cache hit can still take as long as an upstream fetch.
-- Each get on a caching table in the same context overwrites the value, so read it after the `get` you are measuring.
 
-Note that `get()` returns a plain `RecordObject`, not a resource instance — the record itself does not carry cache disposition; read it from the context (or an explicitly passed `RequestTarget`). Prior to Harper 5.1.16, `context.loadedFromSource` was never assigned and the flag was only observable via an explicitly passed `RequestTarget`.
+`get()` returns a plain `RecordObject`, not a resource instance, so the returned record does not itself carry cache disposition — read it from the `RequestTarget` you passed to the get. A `get` called with a plain id has no target to read back, so pass a `RequestTarget` when you need to observe disposition.
 
 #### Source `get` — controlling timestamp and expiration
 
@@ -653,7 +655,6 @@ Returns the current context, which includes:
 
 - `user` — User object with username, role, and authorization information
 - `transaction` — The current transaction
-- `loadedFromSource` — For caching tables (5.1.16+), cache disposition of the most recent `get` in this context: `true` if it went to the source, `false` if served from cache (see [Observing cache disposition](#observing-cache-disposition))
 
 When triggered by HTTP, the context is the `Request` object with these additional properties:
 
@@ -1159,7 +1160,6 @@ getContext is availabe as export from the `harper` module, or as a global variab
 
 - `user` — User object with username, role, and authorization information
 - `transaction` — The current transaction
-- `loadedFromSource` — For caching tables (5.1.16+), cache disposition of the most recent `get` in this context: `true` if it went to the source, `false` if served from cache (see [Observing cache disposition](#observing-cache-disposition))
 
 When triggered by HTTP, the context is the `Request` object with these additional properties: