Add focused Prometheus protocol tests for user-facing native lowering errors: unsupported-but-parseable functions and invalid date-function arity. These are semantic guardrails for clear errors, not broad coverage padding.

Lower label_replace and label_join through the existing time-series tag helpers so native PromQL can transform labelsets without introducing a new IR path. The lowering preserves Prometheus UTF-8 label validation, label_replace's empty source-label behavior, metric-name restoration when __name__ is written, and duplicate-labelset merging with overlap detection.

Also extends focused Prometheus protocol tests and compliance cases for label replacement, joins, empty label names, UTF-8 label names, regex errors, and replacement syntax.

Validation: PYTHONPYCACHEPREFIX=/tmp/ch_pycache_pr7 python3 -m py_compile tests/integration/test_prometheus_protocols/test_evaluation.py tests/integration/test_prometheus_protocols/test_compliance.py; git diff --check; python3 -m ci.praktika run --workflow PR "Build (amd_debug)"; python3 -m ci.praktika run --workflow PR integration --test test_prometheus_protocols/test_evaluation.py::test_label_functions; python3 -m ci.praktika run --workflow PR integration --test test_prometheus_protocols/test_compliance.py::test_promql_compliance.

Avoid fork-local wording in the PromQL review base. These are ClickHouse PromQL regression cases and evidence requirements, not fork-specific artifacts.

Avoid fork-local wording in the PromQL review base. These are ClickHouse PromQL regression cases and evidence requirements, not fork-specific artifacts.

Remove the standalone native histogram discovery Markdown note from the PromQL split branches.

Remove the standalone native histogram discovery Markdown note from the PromQL split branches.

Remove downstream promshim-specific evidence and non-goal language from the native PromQL lowering README so the note stays focused on ClickHouse review guidance.

Remove downstream promshim-specific evidence and non-goal language from the native PromQL lowering README so the note stays focused on ClickHouse review guidance.

Rewrite the native PromQL lowering notes around external SQL-transpiler measurements. Document measured and mixed SQL patterns with target PromQL shapes, pseudocode, and the ClickHouse-side validation expected for in-tree changes.

Rewrite the native PromQL lowering notes around external SQL-transpiler measurements. Document measured and mixed SQL patterns with target PromQL shapes, pseudocode, and the ClickHouse-side validation expected for in-tree changes.

Replace external corpus row names with concrete PromQL expressions and query-range context in the native PromQL lowering notes.

Replace external corpus row names with concrete PromQL expressions and query-range context in the native PromQL lowering notes.

Deduplicate expanded compliance cases by query text before checking the
`should_fail` expectation. A query listed once as expected success and once as
expected failure is now reported as conflicting metadata instead of slipping
through as two separate cases.

…plit/promql-label-functions

Mirror the upstream PromQL compliance corpus for label transformation invalid
label-name cases. These cases should remain should-fail entries so ClickHouse
acceptance of invalid destination labels stays visible as a rejection mismatch
rather than being counted as expected coverage.

…ions

`label_replace` and `label_join` create or read label keys from string
arguments. Keep those arguments constrained to PromQL label-name syntax instead
of accepting every non-empty UTF-8 string, so invalid names such as `~invalid`
are rejected before the SQL path emits inaccessible label keys.

…on-base

…on-base

…ions

…ions

…plit/promql-label-functions

…ions

Use Prometheus UTF-8 label-name validation for label transformation functions, allow zero-source `label_join`, and match Go `regexp.ExpandString` replacement parsing for `label_replace`.

Extend focused integration and compliance coverage for legacy-invalid UTF-8 labels, empty label deletion, metric-name rewrites, missing sources, replacement edge cases, and duplicate transformed labelsets.

Ignore string literals and selector matchers when routing compliance failures by query shape. This keeps report categories from treating label values or exponent signs as binary operators, and recognizes bare '<' and '>' comparisons.

Use the existing eps parameter when checking live Prometheus HTTP results against expected JSON, and compare ClickHouse HTTP output against the live Prometheus result. This keeps numeric drift bounded to eps while preserving exact shape, label, and timestamp checks.

…on-base

…ions

…plit/promql-label-functions

…-base

…functions

Keep the PromQL parser, modifier, and selector fixes from the local matrix pass, but move the high-value regression coverage into the existing protocol and compliance suites instead of adding the standalone matrix harness to the PR branch.\n\nThis keeps fixed-time range evaluation covered through the existing evaluation tests and records the parser, matcher, timestamp-modifier, and sparse range cases in the shared compliance corpus.

Build (arm_tidy) flagged the vector-grid finalization predicate because one call cloned an AST pointer while another argument moved the same pointer. C++ argument evaluation order can make that a use-after-move.\n\nCreate separate AST nodes for the null and stale-marker checks so the generated predicate stays the same without relying on argument evaluation order.

Parse `@ start()` and `@ end()` as timestamp modifier variants instead of
rewriting the raw query text before parsing. This keeps label values and
regular expressions untouched while resolving symbolic bounds in the query
range planner.

Propagate symbolic `@` modifiers through the PromQL tree and SQL lowering so
instant selectors and range-vector functions bind to the query start or end
consistently with Prometheus.

The selector-matcher validation branch should not also introduce symbolic
`@ start()` and `@ end()` modifier parsing. Remove that parser/evaluation
feature from the base branch so the behavior can be reviewed independently.

Move the symbolic timestamp-modifier compliance cases out with the feature.
Keep the offset-only case here because it exercises existing modifier behavior.

Symbolic `@ start()` and `@ end()` modifiers need parser-level handling so
selectors, string literals, and regular expressions are not rewritten as raw
text. Remove the temporary text-substitution path from the base branch; the
symbolic modifier implementation belongs with the dedicated parser change.

…-base

…-base

…ions

# Conflicts:
#	src/Functions/TimeSeries/timeSeriesReplaceTag.cpp
#	src/Interpreters/ContextTimeSeriesTagsCollector.cpp
#	tests/integration/test_prometheus_protocols/test_evaluation.py