feat(cypher): ReentryPlan + multi-whole-row prefix WITH (#989 slices 4.1+4.3a) - #1248

Lifts the failfast at the trailing-MATCH-first-alias check in
``_compile_bounded_reentry_query`` for the free-form case (LDBC SNB IC3
endpoint): when the trailing MATCH binds aliases none of which is in the
prefix WITH's carried whole-row set, treat every carried alias as
non-source and use the trailing MATCH's first alias as the carrier label
for downstream rewrites.

The existing ``_collect_non_source_alias_property_refs`` /
``_rewrite_reentry_expr_to_hidden_properties`` machinery (slice 4.3a/b
from #1248) materializes carried-alias property references as hidden
columns; with this change the same machinery covers free-form cases by
passing all whole-row aliases as ``non_source_alias_names``.

The ``ReentryPlan`` constructed for free-form sets
``free_form=True`` (no ``CarriedAlias`` entry has
``is_reentry_alias=True``) so the runtime can branch into a broadcast
path. The runtime change lands in a follow-up commit; until then,
free-form queries compile but return wrong rows because the existing
``_compiled_query_reentry_state`` still seeds from the wrong alias's
node ids — the regression is gated by the failfast tests (which fail
intentionally at this commit and are retargeted alongside the runtime
commit).

Also tightens the surviving guard from ``first_alias is None or
first_alias != reentry_alias`` to ``first_alias is None`` since the
admit branch now sets ``reentry_alias = first_alias`` for the
previously-rejected case.

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

#1263)

Lands the runtime half of the #1263 conservative admit:

* New ``_compiled_query_freeform_reentry_state`` in ``gfql_unified.py``
  branches on ``ReentryPlan.free_form``. For a single-row prefix WITH
  it broadcasts every ``__cypher_reentry_*`` hidden column from the
  prefix row onto every base node and returns ``start_nodes=None``, so
  the trailing MATCH runs as a regular MATCH and inherits the carried
  values via the row pipeline. Multi-row prefix raises a clear
  failfast pointing at the multi-row free-form follow-up slice.

* Compile gate added in ``_compile_bounded_reentry_query``: when
  ``free_form`` is True AND the trailing scope references any carried
  alias property (e.g. ``WHERE country.id IN [x.id, y.id]`` in literal
  IC3), raise a scoped ``#1263`` failfast pointing at the rewrite-order
  refactor follow-up. The double-rewrite that emerges from composing
  ``_demote_secondary_whole_row_aliases`` (#1071) with
  ``_rewrite_reentry_expr_to_hidden_properties`` (#1248) under
  free-form is deferred to its own focused slice.

End-to-end:
* Simple free-form (``MATCH (a) WITH a MATCH (c)-[:T]->(d) RETURN ...``)
  compiles + executes vectorized on pandas.
* IC3-shape with carried-property WHERE rejects with a scoped #1263
  failfast (clear error pointing at the follow-up).

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

Lifts the failfast at the trailing-MATCH-first-alias check in
``_compile_bounded_reentry_query`` for the free-form case (LDBC SNB IC3
endpoint): when the trailing MATCH binds aliases none of which is in the
prefix WITH's carried whole-row set, treat every carried alias as
non-source and use the trailing MATCH's first alias as the carrier label
for downstream rewrites.

The existing ``_collect_non_source_alias_property_refs`` /
``_rewrite_reentry_expr_to_hidden_properties`` machinery (slice 4.3a/b
from #1248) materializes carried-alias property references as hidden
columns; with this change the same machinery covers free-form cases by
passing all whole-row aliases as ``non_source_alias_names``.

The ``ReentryPlan`` constructed for free-form sets
``free_form=True`` (no ``CarriedAlias`` entry has
``is_reentry_alias=True``) so the runtime can branch into a broadcast
path. The runtime change lands in a follow-up commit; until then,
free-form queries compile but return wrong rows because the existing
``_compiled_query_reentry_state`` still seeds from the wrong alias's
node ids — the regression is gated by the failfast tests (which fail
intentionally at this commit and are retargeted alongside the runtime
commit).

Also tightens the surviving guard from ``first_alias is None or
first_alias != reentry_alias`` to ``first_alias is None`` since the
admit branch now sets ``reentry_alias = first_alias`` for the
previously-rejected case.

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

#1263)

Lands the runtime half of the #1263 conservative admit:

* New ``_compiled_query_freeform_reentry_state`` in ``gfql_unified.py``
  branches on ``ReentryPlan.free_form``. For a single-row prefix WITH
  it broadcasts every ``__cypher_reentry_*`` hidden column from the
  prefix row onto every base node and returns ``start_nodes=None``, so
  the trailing MATCH runs as a regular MATCH and inherits the carried
  values via the row pipeline. Multi-row prefix raises a clear
  failfast pointing at the multi-row free-form follow-up slice.

* Compile gate added in ``_compile_bounded_reentry_query``: when
  ``free_form`` is True AND the trailing scope references any carried
  alias property (e.g. ``WHERE country.id IN [x.id, y.id]`` in literal
  IC3), raise a scoped ``#1263`` failfast pointing at the rewrite-order
  refactor follow-up. The double-rewrite that emerges from composing
  ``_demote_secondary_whole_row_aliases`` (#1071) with
  ``_rewrite_reentry_expr_to_hidden_properties`` (#1248) under
  free-form is deferred to its own focused slice.

End-to-end:
* Simple free-form (``MATCH (a) WITH a MATCH (c)-[:T]->(d) RETURN ...``)
  compiles + executes vectorized on pandas.
* IC3-shape with carried-property WHERE rejects with a scoped #1263
  failfast (clear error pointing at the follow-up).

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* feat(cypher/ir): add ReentryPlan.free_form marker for intermediate MATCH (#1263)

Adds a `free_form: bool = False` field to `ReentryPlan` so the runtime can
distinguish the LDBC SNB IC3 free-form intermediate MATCH shape from the
existing whole-row and scalar-only prefix shapes.

When the trailing MATCH after a prefix `WITH` introduces aliases none of
which is in the carried set, no carried alias anchors the seed pattern.
The runtime needs to broadcast carried columns onto the base node table
(single-prefix-row) or fall back to per-row union (multi-prefix-row) so
the trailing MATCH cross-joins implicitly via the row pipeline.

Default value preserves existing whole-row and scalar-only behavior.
Compile + runtime branches that consume this marker land in subsequent
commits.

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* feat(cypher): admit free-form intermediate MATCH at compile (#1263)

Lifts the failfast at the trailing-MATCH-first-alias check in
``_compile_bounded_reentry_query`` for the free-form case (LDBC SNB IC3
endpoint): when the trailing MATCH binds aliases none of which is in the
prefix WITH's carried whole-row set, treat every carried alias as
non-source and use the trailing MATCH's first alias as the carrier label
for downstream rewrites.

The existing ``_collect_non_source_alias_property_refs`` /
``_rewrite_reentry_expr_to_hidden_properties`` machinery (slice 4.3a/b
from #1248) materializes carried-alias property references as hidden
columns; with this change the same machinery covers free-form cases by
passing all whole-row aliases as ``non_source_alias_names``.

The ``ReentryPlan`` constructed for free-form sets
``free_form=True`` (no ``CarriedAlias`` entry has
``is_reentry_alias=True``) so the runtime can branch into a broadcast
path. The runtime change lands in a follow-up commit; until then,
free-form queries compile but return wrong rows because the existing
``_compiled_query_reentry_state`` still seeds from the wrong alias's
node ids — the regression is gated by the failfast tests (which fail
intentionally at this commit and are retargeted alongside the runtime
commit).

Also tightens the surviving guard from ``first_alias is None or
first_alias != reentry_alias`` to ``first_alias is None`` since the
admit branch now sets ``reentry_alias = first_alias`` for the
previously-rejected case.

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* feat(cypher): runtime broadcast for simple free-form + scoped failfast (#1263)

Lands the runtime half of the #1263 conservative admit:

* New ``_compiled_query_freeform_reentry_state`` in ``gfql_unified.py``
  branches on ``ReentryPlan.free_form``. For a single-row prefix WITH
  it broadcasts every ``__cypher_reentry_*`` hidden column from the
  prefix row onto every base node and returns ``start_nodes=None``, so
  the trailing MATCH runs as a regular MATCH and inherits the carried
  values via the row pipeline. Multi-row prefix raises a clear
  failfast pointing at the multi-row free-form follow-up slice.

* Compile gate added in ``_compile_bounded_reentry_query``: when
  ``free_form`` is True AND the trailing scope references any carried
  alias property (e.g. ``WHERE country.id IN [x.id, y.id]`` in literal
  IC3), raise a scoped ``#1263`` failfast pointing at the rewrite-order
  refactor follow-up. The double-rewrite that emerges from composing
  ``_demote_secondary_whole_row_aliases`` (#1071) with
  ``_rewrite_reentry_expr_to_hidden_properties`` (#1248) under
  free-form is deferred to its own focused slice.

End-to-end:
* Simple free-form (``MATCH (a) WITH a MATCH (c)-[:T]->(d) RETURN ...``)
  compiles + executes vectorized on pandas.
* IC3-shape with carried-property WHERE rejects with a scoped #1263
  failfast (clear error pointing at the follow-up).

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* test(cypher): retarget free-form failfast tests for #1263 conservative admit

Two #1263 regression-locks added in #1270 expected the carried-alias gate to
fire for free-form intermediate MATCH. The conservative admit landed in the
preceding commits flips the simple shape from rejection to positive
execution and tightens the rejection scope to the carried-property variant:

* ``test_string_cypher_failfast_rejects_intermediate_reentry_match_with_no_carried_source``
  → renamed to ``..._with_carried_property_in_trailing_where`` and pinned to
  the new scoped #1263 failfast (carried-alias property in trailing scope).
* ``test_string_cypher_failfast_rejects_simple_freeform_intermediate_reentry_match``
  → renamed to ``test_string_cypher_executes_simple_freeform_intermediate_reentry_match``
  and converted to positive: asserts the trailing MATCH binds correctly
  against the broadcast carried row table.
* New ``..._on_cudf_when_available`` mirror with ``pytest.importorskip("cudf")``
  for engine parity per coordinator def-of-done.

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* test(cypher): add multi-prefix-row free-form failfast regression (#1263)

Wave 1 review (single CONFIRMED IMPORTANT): the runtime failfast at
gfql_unified.py for multi-prefix-row free-form admit was untested. Adds a
positive regression-lock that builds a 2-row prefix and asserts the scoped
``single-row prefix WITH only`` failfast wording.

Refs #1263

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* docs(changelog): #1263 simple free-form intermediate MATCH admit

Records the conservative #1263 close: simple free-form admit + scoped
failfast for the carried-property-in-trailing-WHERE variant + runtime
broadcast helper + retargeted regression tests + three TCK admits.

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* test(cypher): Wave 2 amplification — multi-carried + empty prefix free-form (#1263)

Wave 2 review per agents/skills/review/SKILL.md confirmed convergence
(two consecutive non-significant-advance waves) and surfaced two
amplification SUGGESTIONs that the reviewers verified produce correct
behavior. Locking the contract:

* test_string_cypher_executes_freeform_intermediate_reentry_match_with_multi_carried_aliases
  — covers `WITH a, b MATCH (c)-[:T]->(d)` shape (multi-carried-aliases admit).
* test_string_cypher_executes_freeform_intermediate_reentry_match_with_empty_prefix
  — covers `_compiled_query_freeform_reentry_state`'s empty-prefix
  early-return path.

Refs #1263

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <[email protected]>

* feat(cypher/ir): add ReentryPlan.free_form marker for intermediate MATCH (#1263)

Adds a `free_form: bool = False` field to `ReentryPlan` so the runtime can
distinguish the LDBC SNB IC3 free-form intermediate MATCH shape from the
existing whole-row and scalar-only prefix shapes.

When the trailing MATCH after a prefix `WITH` introduces aliases none of
which is in the carried set, no carried alias anchors the seed pattern.
The runtime needs to broadcast carried columns onto the base node table
(single-prefix-row) or fall back to per-row union (multi-prefix-row) so
the trailing MATCH cross-joins implicitly via the row pipeline.

Default value preserves existing whole-row and scalar-only behavior.
Compile + runtime branches that consume this marker land in subsequent
commits.

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* feat(cypher): admit free-form intermediate MATCH at compile (#1263)

Lifts the failfast at the trailing-MATCH-first-alias check in
``_compile_bounded_reentry_query`` for the free-form case (LDBC SNB IC3
endpoint): when the trailing MATCH binds aliases none of which is in the
prefix WITH's carried whole-row set, treat every carried alias as
non-source and use the trailing MATCH's first alias as the carrier label
for downstream rewrites.

The existing ``_collect_non_source_alias_property_refs`` /
``_rewrite_reentry_expr_to_hidden_properties`` machinery (slice 4.3a/b
from #1248) materializes carried-alias property references as hidden
columns; with this change the same machinery covers free-form cases by
passing all whole-row aliases as ``non_source_alias_names``.

The ``ReentryPlan`` constructed for free-form sets
``free_form=True`` (no ``CarriedAlias`` entry has
``is_reentry_alias=True``) so the runtime can branch into a broadcast
path. The runtime change lands in a follow-up commit; until then,
free-form queries compile but return wrong rows because the existing
``_compiled_query_reentry_state`` still seeds from the wrong alias's
node ids — the regression is gated by the failfast tests (which fail
intentionally at this commit and are retargeted alongside the runtime
commit).

Also tightens the surviving guard from ``first_alias is None or
first_alias != reentry_alias`` to ``first_alias is None`` since the
admit branch now sets ``reentry_alias = first_alias`` for the
previously-rejected case.

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* feat(cypher): runtime broadcast for simple free-form + scoped failfast (#1263)

Lands the runtime half of the #1263 conservative admit:

* New ``_compiled_query_freeform_reentry_state`` in ``gfql_unified.py``
  branches on ``ReentryPlan.free_form``. For a single-row prefix WITH
  it broadcasts every ``__cypher_reentry_*`` hidden column from the
  prefix row onto every base node and returns ``start_nodes=None``, so
  the trailing MATCH runs as a regular MATCH and inherits the carried
  values via the row pipeline. Multi-row prefix raises a clear
  failfast pointing at the multi-row free-form follow-up slice.

* Compile gate added in ``_compile_bounded_reentry_query``: when
  ``free_form`` is True AND the trailing scope references any carried
  alias property (e.g. ``WHERE country.id IN [x.id, y.id]`` in literal
  IC3), raise a scoped ``#1263`` failfast pointing at the rewrite-order
  refactor follow-up. The double-rewrite that emerges from composing
  ``_demote_secondary_whole_row_aliases`` (#1071) with
  ``_rewrite_reentry_expr_to_hidden_properties`` (#1248) under
  free-form is deferred to its own focused slice.

End-to-end:
* Simple free-form (``MATCH (a) WITH a MATCH (c)-[:T]->(d) RETURN ...``)
  compiles + executes vectorized on pandas.
* IC3-shape with carried-property WHERE rejects with a scoped #1263
  failfast (clear error pointing at the follow-up).

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* test(cypher): retarget free-form failfast tests for #1263 conservative admit

Two #1263 regression-locks added in #1270 expected the carried-alias gate to
fire for free-form intermediate MATCH. The conservative admit landed in the
preceding commits flips the simple shape from rejection to positive
execution and tightens the rejection scope to the carried-property variant:

* ``test_string_cypher_failfast_rejects_intermediate_reentry_match_with_no_carried_source``
  → renamed to ``..._with_carried_property_in_trailing_where`` and pinned to
  the new scoped #1263 failfast (carried-alias property in trailing scope).
* ``test_string_cypher_failfast_rejects_simple_freeform_intermediate_reentry_match``
  → renamed to ``test_string_cypher_executes_simple_freeform_intermediate_reentry_match``
  and converted to positive: asserts the trailing MATCH binds correctly
  against the broadcast carried row table.
* New ``..._on_cudf_when_available`` mirror with ``pytest.importorskip("cudf")``
  for engine parity per coordinator def-of-done.

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* test(cypher): add multi-prefix-row free-form failfast regression (#1263)

Wave 1 review (single CONFIRMED IMPORTANT): the runtime failfast at
gfql_unified.py for multi-prefix-row free-form admit was untested. Adds a
positive regression-lock that builds a 2-row prefix and asserts the scoped
``single-row prefix WITH only`` failfast wording.

Refs #1263

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* docs(changelog): #1263 simple free-form intermediate MATCH admit

Records the conservative #1263 close: simple free-form admit + scoped
failfast for the carried-property-in-trailing-WHERE variant + runtime
broadcast helper + retargeted regression tests + three TCK admits.

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* test(cypher): Wave 2 amplification — multi-carried + empty prefix free-form (#1263)

Wave 2 review per agents/skills/review/SKILL.md confirmed convergence
(two consecutive non-significant-advance waves) and surfaced two
amplification SUGGESTIONs that the reviewers verified produce correct
behavior. Locking the contract:

* test_string_cypher_executes_freeform_intermediate_reentry_match_with_multi_carried_aliases
  — covers `WITH a, b MATCH (c)-[:T]->(d)` shape (multi-carried-aliases admit).
* test_string_cypher_executes_freeform_intermediate_reentry_match_with_empty_prefix
  — covers `_compiled_query_freeform_reentry_state`'s empty-prefix
  early-return path.

Refs #1263

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <[email protected]>

…is defaults (#1280)

* phase1: validators, deep ring axis checks, and persist axis defaults

* fix: satisfy mypy for dataset_id URL refresh helper

* fix: make validate_settings typing compatible with python 3.8

* refactor: centralize axis field constants and typed dict contracts

* docs(changelog): record settings/axis validation + persist defaults work

* refactor(validate): centralize ring axis payload validators

* types(validate): add named url params/react settings aliases

* types(url_params): propagate named URLParamsDict across APIs

* feat(cypher): admit simple free-form intermediate MATCH (#1263) (#1279)

* feat(cypher/ir): add ReentryPlan.free_form marker for intermediate MATCH (#1263)

Adds a `free_form: bool = False` field to `ReentryPlan` so the runtime can
distinguish the LDBC SNB IC3 free-form intermediate MATCH shape from the
existing whole-row and scalar-only prefix shapes.

When the trailing MATCH after a prefix `WITH` introduces aliases none of
which is in the carried set, no carried alias anchors the seed pattern.
The runtime needs to broadcast carried columns onto the base node table
(single-prefix-row) or fall back to per-row union (multi-prefix-row) so
the trailing MATCH cross-joins implicitly via the row pipeline.

Default value preserves existing whole-row and scalar-only behavior.
Compile + runtime branches that consume this marker land in subsequent
commits.

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* feat(cypher): admit free-form intermediate MATCH at compile (#1263)

Lifts the failfast at the trailing-MATCH-first-alias check in
``_compile_bounded_reentry_query`` for the free-form case (LDBC SNB IC3
endpoint): when the trailing MATCH binds aliases none of which is in the
prefix WITH's carried whole-row set, treat every carried alias as
non-source and use the trailing MATCH's first alias as the carrier label
for downstream rewrites.

The existing ``_collect_non_source_alias_property_refs`` /
``_rewrite_reentry_expr_to_hidden_properties`` machinery (slice 4.3a/b
from #1248) materializes carried-alias property references as hidden
columns; with this change the same machinery covers free-form cases by
passing all whole-row aliases as ``non_source_alias_names``.

The ``ReentryPlan`` constructed for free-form sets
``free_form=True`` (no ``CarriedAlias`` entry has
``is_reentry_alias=True``) so the runtime can branch into a broadcast
path. The runtime change lands in a follow-up commit; until then,
free-form queries compile but return wrong rows because the existing
``_compiled_query_reentry_state`` still seeds from the wrong alias's
node ids — the regression is gated by the failfast tests (which fail
intentionally at this commit and are retargeted alongside the runtime
commit).

Also tightens the surviving guard from ``first_alias is None or
first_alias != reentry_alias`` to ``first_alias is None`` since the
admit branch now sets ``reentry_alias = first_alias`` for the
previously-rejected case.

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* feat(cypher): runtime broadcast for simple free-form + scoped failfast (#1263)

Lands the runtime half of the #1263 conservative admit:

* New ``_compiled_query_freeform_reentry_state`` in ``gfql_unified.py``
  branches on ``ReentryPlan.free_form``. For a single-row prefix WITH
  it broadcasts every ``__cypher_reentry_*`` hidden column from the
  prefix row onto every base node and returns ``start_nodes=None``, so
  the trailing MATCH runs as a regular MATCH and inherits the carried
  values via the row pipeline. Multi-row prefix raises a clear
  failfast pointing at the multi-row free-form follow-up slice.

* Compile gate added in ``_compile_bounded_reentry_query``: when
  ``free_form`` is True AND the trailing scope references any carried
  alias property (e.g. ``WHERE country.id IN [x.id, y.id]`` in literal
  IC3), raise a scoped ``#1263`` failfast pointing at the rewrite-order
  refactor follow-up. The double-rewrite that emerges from composing
  ``_demote_secondary_whole_row_aliases`` (#1071) with
  ``_rewrite_reentry_expr_to_hidden_properties`` (#1248) under
  free-form is deferred to its own focused slice.

End-to-end:
* Simple free-form (``MATCH (a) WITH a MATCH (c)-[:T]->(d) RETURN ...``)
  compiles + executes vectorized on pandas.
* IC3-shape with carried-property WHERE rejects with a scoped #1263
  failfast (clear error pointing at the follow-up).

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* test(cypher): retarget free-form failfast tests for #1263 conservative admit

Two #1263 regression-locks added in #1270 expected the carried-alias gate to
fire for free-form intermediate MATCH. The conservative admit landed in the
preceding commits flips the simple shape from rejection to positive
execution and tightens the rejection scope to the carried-property variant:

* ``test_string_cypher_failfast_rejects_intermediate_reentry_match_with_no_carried_source``
  → renamed to ``..._with_carried_property_in_trailing_where`` and pinned to
  the new scoped #1263 failfast (carried-alias property in trailing scope).
* ``test_string_cypher_failfast_rejects_simple_freeform_intermediate_reentry_match``
  → renamed to ``test_string_cypher_executes_simple_freeform_intermediate_reentry_match``
  and converted to positive: asserts the trailing MATCH binds correctly
  against the broadcast carried row table.
* New ``..._on_cudf_when_available`` mirror with ``pytest.importorskip("cudf")``
  for engine parity per coordinator def-of-done.

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* test(cypher): add multi-prefix-row free-form failfast regression (#1263)

Wave 1 review (single CONFIRMED IMPORTANT): the runtime failfast at
gfql_unified.py for multi-prefix-row free-form admit was untested. Adds a
positive regression-lock that builds a 2-row prefix and asserts the scoped
``single-row prefix WITH only`` failfast wording.

Refs #1263

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* docs(changelog): #1263 simple free-form intermediate MATCH admit

Records the conservative #1263 close: simple free-form admit + scoped
failfast for the carried-property-in-trailing-WHERE variant + runtime
broadcast helper + retargeted regression tests + three TCK admits.

Refs #1263 #999 #989

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

* test(cypher): Wave 2 amplification — multi-carried + empty prefix free-form (#1263)

Wave 2 review per agents/skills/review/SKILL.md confirmed convergence
(two consecutive non-significant-advance waves) and surfaced two
amplification SUGGESTIONs that the reviewers verified produce correct
behavior. Locking the contract:

* test_string_cypher_executes_freeform_intermediate_reentry_match_with_multi_carried_aliases
  — covers `WITH a, b MATCH (c)-[:T]->(d)` shape (multi-carried-aliases admit).
* test_string_cypher_executes_freeform_intermediate_reentry_match_with_empty_prefix
  — covers `_compiled_query_freeform_reentry_state`'s empty-prefix
  early-return path.

Refs #1263

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <[email protected]>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <[email protected]>