Fix SessionUi::elicitation wire field name

The hand-authored `SessionUi::elicitation` convenience layer was
sending the JSON Schema payload as `"schema"` on the wire, but the
`session.ui.elicitation` request shape expects `"requestedSchema"`.
This is the field name in:

- this crate's own generated UIElicitationRequest type
  (rust/src/generated/api_types.rs:1721, serde renames to
  `requestedSchema` via #[serde(rename_all = "camelCase")])
- the generated typed RPC wrapper SessionRpcUi::elicitation
  (rust/src/generated/rpc.rs:1245-1257), which is correct
- and the same wire field used by every other SDK we ship

So every elicitation call from the SessionUi convenience layer was
effectively dead — the CLI saw a missing required `requestedSchema`
field. The `confirm` / `select` / `input` helpers all delegate to
`elicitation`, so they were dead too.

The mock-server test for elicitation round-tripped through the same
misnamed field on both ends, so the bug slipped past unit tests
(`assert_eq!(request["params"]["schema"], schema)` matched the buggy
implementation). The fix is a one-line rename in session.rs plus a
test update that now asserts on `requestedSchema` and explicitly
rejects a stray `schema` key, so we can't regress the same way.

207 tests pass. doc / clippy / fmt clean.

Caught by the gap-analysis re-run before 0.1.0 cut. Wire-shape
divergence between hand-authored and generated layers — same class
of bug as the workspace RPC fix earlier in this stack.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: tclem

rust/CHANGELOG.md

@@ -315,6 +315,19 @@ public surface.
   `lifecycle_observer`.
 - `RELEASING.md` operational runbook for maintainers.
 
+### Fixed
+- `SessionUi::elicitation` (and the `confirm` / `select` / `input`
+  convenience helpers that delegate through it) now sends the user-supplied
+  JSON Schema as `requestedSchema` on the wire, matching the
+  `session.ui.elicitation` request shape that all other SDKs ship and that
+  this crate's own generated `UIElicitationRequest` type expects. The
+  hand-authored convenience layer was sending it as `schema`, so every UI
+  helper call was effectively dead — the CLI saw a missing required
+  `requestedSchema` field. The mock-server test for elicitation
+  round-tripped through the same misnamed field, so the bug slipped past
+  unit tests; the test now asserts on `requestedSchema` and explicitly
+  rejects a stray `schema` key.
+
 ### Notes
 - Minimum supported Rust version (MSRV): 1.94.0 (pinned via
   `rust-toolchain.toml`).

rust/src/session.rs

@@ -593,7 +593,7 @@ impl<'a> SessionUi<'a> {
                 Some(serde_json::json!({
                     "sessionId": self.session.id,
                     "message": message,
-                    "schema": schema,
+                    "requestedSchema": schema,
                 })),
             )
             .await?;

rust/tests/session_test.rs

@@ -1244,7 +1244,11 @@ async fn elicitation_returns_typed_result() {
     let request = server.read_request().await;
     assert_eq!(request["method"], "session.ui.elicitation");
     assert_eq!(request["params"]["message"], "Enter your name");
-    assert_eq!(request["params"]["schema"], schema);
+    assert_eq!(request["params"]["requestedSchema"], schema);
+    assert!(
+        request["params"].get("schema").is_none(),
+        "wire field is `requestedSchema`, not `schema`"
+    );
     server
         .respond(
             &request,