* test(agents): multi-turn message-stream invariants (graph integration)
Add a graph-integration net for the class of bug behind #3684: build a real
create_agent graph with DynamicContextMiddleware plus a checkpointer, drive two
user turns on one thread with a deterministic fake model and memory injection
stubbed on, then assert the message stream stays well-formed -- the newest user
message is the latest human turn, no duplicate ids, no __user__user suffix
explosion.
Runs at unit speed in `make test` (backend-unit-tests), with no gateway, SSE,
fixtures, or API key. Verified red on the pre-fix middleware and green after.
Catches this class earlier than e2e replay, which disables memory, uses a
single-turn golden, and asserts SSE shape only.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
* test(agents): address review — semantic-first asserts, _STREAM_MIDDLEWARES, DRY
- Check the semantic invariant (newest user message is the latest human turn)
before the structural id checks, so a regression surfaces as a meaning-level
failure; verified it now fails first on the pre-#3685 middleware.
- Add module-level _STREAM_MIDDLEWARES (the docstring referenced it; it did not
exist) so the net is trivially widened with more state-touching middlewares.
- _last_human_text reuses _msg_text instead of re-implementing content flattening.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
