diff --git a/.changeset/24043-http-request-body-tsdoc.md b/.changeset/24043-http-request-body-tsdoc.md
new file mode 100644
index 0000000000..a0c326a171
--- /dev/null
+++ b/.changeset/24043-http-request-body-tsdoc.md
@@ -0,0 +1,12 @@
+---
+"@objectstack/spec": patch
+---
+
+docs(spec): `IHttpRequest.body`'s TSDoc says what a handler reads, and that reading it may refuse
+
+Clause-②: no
+
+- **What it is.** The parsed JSON document for `application/json`, or the parsed fields of a `multipart/form-data` or `application/x-www-form-urlencoded` form; `{}` when the request carries no body.
+- **It may refuse.** An implementation that cannot parse the body, or does not read its media type, throws from the read instead of handing over an invented value. The standard transport (`@objectstack/plugin-hono-server`) does, and answers 400 `INVALID_REQUEST` itself, replacing whatever the handler wrote. So a handler must not catch the refusal and carry on.
+- **Raw bytes.** A handler that needs them reads `rawBody()` and never reads `body`.
+- **Unchanged:** the type (`body?: any`), every other member, and every runtime behaviour. This is prose in the shipped `.d.ts` only.
diff --git a/packages/spec/src/contracts/http-server.ts b/packages/spec/src/contracts/http-server.ts
index 09bfeb1d50..e822aaf80d 100644
--- a/packages/spec/src/contracts/http-server.ts
+++ b/packages/spec/src/contracts/http-server.ts
@@ -20,7 +20,23 @@ export interface IHttpRequest {
     params: Record<string, string>;
     /** Request query parameters */
     query: Record<string, string | string[]>;
-    /** Request body (parsed — JSON or form data when applicable) */
+    /**
+     * Request body, parsed by its declared content type: the parsed JSON
+     * document for `application/json`, or the parsed fields of a form
+     * (`multipart/form-data`, `application/x-www-form-urlencoded`). `{}` when
+     * the request carries no body.
+     *
+     * Reading it may REFUSE: an implementation that cannot parse the body, or
+     * that does not read the body's media type, throws from the read rather
+     * than hand over an invented value. The standard transport
+     * (`@objectstack/plugin-hono-server`) does, and answers the request itself
+     * with 400 `INVALID_REQUEST`, replacing whatever the handler wrote; so a
+     * handler must not catch the refusal and carry on, because anything it
+     * does after the catch acts on a request that has already been refused.
+     *
+     * A handler that needs the raw bytes (a file upload, a media type not
+     * listed above) reads {@link rawBody} and never reads `body`.
+     */
     body?: any;
     /** Request headers */
     headers: Record<string, string | string[]>;