* fix: generate title for interrupted first turn
* test(title): cover partial-exchange + dict-form messages
Harden the interrupted-run fallback path added in 19fc34fd:
- TitleMiddleware._should_generate_title now accepts a lone first-turn
user message when allow_partial_exchange=True, so the worker can still
derive a title if cancellation lands before any AI chunk is checkpointed.
- runtime/runs/worker._ensure_interrupted_title computes the next
checkpoint step defensively (treat missing/non-int step as 0) and
renames a shadowed ckpt_config local for readability.
- Add four unit tests in tests/test_title_middleware_core_logic.py:
partial-exchange allows user-only, partial-exchange still respects an
existing title, dict-form messages are recognized, and the sync
fallback path derives a title from dict-form messages — matching what
channel_values stores in the checkpoint.
Refs #3859.
* fix: persist interrupted-title via channel_versions bump
Address PR #3874 review feedback: ``_ensure_interrupted_title`` previously
called ``aput(..., new_versions={})``. LangGraph's DB-backed savers
(``PostgresSaver`` and the v4 ``SqliteSaver`` blob layout) strip inline
``channel_values`` from ``put`` and only persist blobs for channels named
in ``new_versions`` — so the fallback ``title`` channel was dropped on
read-back and ``threads_meta.display_name`` stayed ``"Untitled"`` after
refresh on those backends. The original in-memory e2e passed because
``InMemorySaver`` keeps the inline snapshot verbatim.
Fix mirrors ``_rollback_to_pre_run_checkpoint`` in the same file: bump
``channel_versions["title"]`` (via ``checkpointer.get_next_version`` when
available, else int/string fallbacks), persist the new version on the
checkpoint, and declare it in ``new_versions`` so the DB savers actually
write the blob.
Regression coverage in ``tests/test_run_worker_rollback.py``:
- ``test_ensure_interrupted_title_bumps_channel_version_and_declares_it_in_new_versions``
— exact ``aput`` invariants: ``new_versions == {"title": 1}``, the
written checkpoint's ``channel_versions["title"]`` is bumped, and the
pre-existing ``messages`` version is preserved.
- ``test_ensure_interrupted_title_bumps_existing_string_version`` —
string-shaped prior version (some savers use UUID-style versions);
bumped value must differ from the prior, no overwrite-in-place.
- ``test_ensure_interrupted_title_skips_when_title_already_set`` — title
short-circuit; no extra ``aput``.
- ``test_ensure_interrupted_title_returns_none_when_no_checkpoint`` —
no checkpoint yet; returns ``None`` without writing.
- ``test_ensure_interrupted_title_round_trip_with_real_sqlite_checkpointer``
— full round-trip against a real ``AsyncSqliteSaver`` on a disk-backed
DB, then closes and re-opens the saver to simulate a fresh
connection. The fallback title must still be present on the second
``aget_tuple``. This is the exact scenario the review flagged.
Validated locally with the full backend suite: 5195 passed, 18 skipped.
Refs #3859. Addresses review on #3874.
* test(worker, title): harden interrupted-title fallback for every saver
Defensive coverage on top of the channel_versions fix (commit 05253957),
addressing edge cases surfaced during a second-pass review of #3874.
Worker:
- Extract version bump into ``_bump_channel_version(checkpointer, current)``
with explicit fallbacks for int / float / numeric-string / UUID-shaped
string / None / bool, AND a wrap-around defense when the saver's
``get_next_version`` raises or returns an unchanged value. The
invariant is: returned version MUST differ from the prior. Without
this, a saver bug (or a custom backend) could leave
``new_versions={"title": v}`` no-op on DB savers — the very class of
bug the original review pointed out.
Title middleware:
- Coerce ``state.get("messages")`` from ``None`` to ``[]`` on both
``_should_generate_title`` and ``_build_title_prompt``. A
partially-initialized checkpoint can carry ``messages=None`` on the
channel_values channel (the worker reads raw channel_values, not
BaseMessages), and the default kwarg only protects against a missing
key. Repro: ``TypeError: 'NoneType' object is not iterable`` from
the next() generator — confirmed by reverting the fix and watching
``test_*_handles_none_messages_channel`` go red.
Tests (TDD-verified red→green for the new asserts):
- ``test_run_worker_rollback.py``:
* ``_bump_channel_version`` — 8 tests covering every version type
(int, float, numeric string, UUID-style string, None, bool) and
every saver-side fault mode (no ``get_next_version`` / raising /
stuck on identity).
* ``test_ensure_interrupted_title_*`` — 5 additional helper
boundary tests: title.enabled=false short-circuit; empty
messages list; messages=None; aput-error propagation (helper
contract: caller swallows, not the helper); idempotency on a
real InMemorySaver across two invocations.
* ``test_ensure_interrupted_title_preserves_non_title_channel_versions``
— pins that ``new_versions`` only contains ``"title"`` and that
other channels' versions are untouched (regression anchor for a
sloppier draft that bumped every channel).
* ``test_worker_finally_block_swallows_helper_exceptions`` — pins
the integration contract: even if the helper raises, the worker's
threads_meta status sync still runs and ``publish_end`` is still
awaited so the SSE stream closes cleanly.
- ``test_title_middleware_core_logic.py``:
* 4 additional tests: ``messages=None`` on both
``_should_generate_title`` and ``_build_title_prompt``; the
``role: user`` / ``role: assistant`` (OpenAI-style) dict
normalization; partial-exchange path with a dict-form message.
Verification:
- ``PYTHONPATH=. uv run pytest tests/ -x --ignore=tests/blocking_io -q``
→ 5215 passed, 18 skipped.
- ``ruff check`` + ``ruff format --check`` clean on every touched file.
- Red/green TDD verification: temporarily reverted the
``new_versions={}`` fix → 4 new tests went red as expected; restored
and the suite is green again. Same red/green dance for the
``messages=None`` coercion.
Refs #3859. Addresses second-pass review on #3874.
* fix(title): ignore dict context reminders in fallback
* fix(worker): link interrupted-title checkpoint to its parent
The title-bump checkpoint written by ``_ensure_interrupted_title`` was
landing without a ``parent_checkpoint_id`` — a real orphan in the
LangGraph history graph. Reproduction (disk-backed AsyncSqliteSaver):
[seed] checkpoint_id = 1f173dbc...
[helper] wrote title = "Why is the sky blue?"
[issue 1] new checkpoint = 1f173dbc..., parent = None
[issue 1] is new checkpoint orphaned? True
Root cause: ``_ensure_interrupted_title`` built ``write_config`` as
``{"thread_id": ..., "checkpoint_ns": ...}`` only. ``BaseCheckpointSaver``
implementations read ``configurable.checkpoint_id`` from that config as
the *parent* id when inserting (see ``langgraph/checkpoint/sqlite/aio.py``
``aput``: ``config["configurable"].get("checkpoint_id")`` becomes the
``parent_checkpoint_id`` column). With no value, the saver writes NULL —
the new checkpoint is a tree root.
Consequences:
- Any future LangGraph ``runs.resume_from`` / time-travel feature has no
backward edge to walk past the title-bump.
- History-visualization UIs built on ``alist()`` render the title-bump as
a sibling of the prior checkpoint, not its descendant.
Fix: read ``checkpoint_id`` off the tuple's own config and thread it into
``write_config["configurable"]["checkpoint_id"]`` before calling ``aput``,
the same pattern every middleware-driven write uses.
Three new regression tests against real ``AsyncSqliteSaver`` (disk-backed,
fresh connections so we exercise the on-disk read path):
- ``test_ensure_interrupted_title_links_new_checkpoint_to_its_parent`` —
asserts ``latest.parent_config["configurable"]["checkpoint_id"]`` equals
the seeded checkpoint id. TDD red-green verified: reverting the fix
flips this test red with ``AssertionError: title-bump checkpoint must
have a parent_config``.
- ``test_ensure_interrupted_title_appears_in_history_with_audit_marker``
— pins the audit contract: the title-bump entry in ``alist()`` carries
``metadata.source == "update"`` and ``metadata.writes`` contains
``runtime_interrupt_title``. This is a deliberate design choice — we
do NOT hide the entry from history (audit trail belongs in the saver),
but its source and writes marker MUST be unambiguous so UIs/tools can
identify it.
- ``test_ensure_interrupted_title_survives_immediate_next_turn`` —
cancel → immediate user follow-up scenario. Simulates the agent's next
turn appending a (user, ai) pair without touching the title channel,
then opens a fresh saver and verifies the title is still present after
the next-turn checkpoint write. Pins the channel-version-blob
invariant established by commit 05253957 — without the
``new_versions={"title": v}`` declaration there, the title blob would
vanish from the DB and this test would read back ``None``.
Verification:
- ``PYTHONPATH=. uv run pytest tests/ -x --ignore=tests/blocking_io -q``
→ 5222 passed, 15 skipped.
- ``ruff check`` + ``ruff format --check`` clean on every touched file.
- Reproduction script confirms ``parent_checkpoint_id`` is now non-null
and the next-turn read-back preserves the fallback title.
Refs #3859.
* Revert "fix(worker): link interrupted-title checkpoint to its parent"
This reverts commit c763ed9334781db1acdce0f5f33d663d8d5f80ff.
* test: trim over-engineered test coverage
Reduce review surface area on PR #3874 by dropping defensive tests that
don't pin a real invariant. After self-review:
- ``_bump_channel_version``: 8 tests → 2 (happy path + saver-error
fallback). Dropped float / bool / numeric-string / UUID-string /
missing-get-next-version / stuck-get-next-version branches — those
are speculative scaffolding for savers we don't ship.
- ``_ensure_interrupted_title``: dropped ``returns_none_when_title_disabled``,
``returns_none_with_no_user_message``, ``returns_none_when_no_checkpoint``
— boundary guards already exercised by the e2e test and the
``handles_none_messages_channel`` regression anchor.
Net: -107 lines of test code. Remaining coverage still pins every
red-green-verified invariant (channel_versions bump, string-version
bump, idempotency, sqlite round-trip, non-title channel preservation,
aput-error contract, worker finally swallowing, partial-exchange).
Verification: 5209 passed, 15 skipped.
* fix: harden interrupted title finalization
* fix: serialize interrupted title finalization
* fix: preserve interrupt semantics during title finalization
* fix: preserve delayed interrupted title recovery
---------
Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
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