[JackieTien97]

Description

Agent guidance is centralized despite module-specific build, grammar, and dependency constraints, while the GROUP BY TAGS IT duplicates per-node result comparison logic.

• Add scoped AGENTS.md guides for AINode, both SQL grammar modules, node/calc commons, distribution, and scripts. Link them from the root, move existing specialized rules to their owning modules, and require semantically equivalent, narrowly scoped backports from master to dev/1.3.
• Add a tree-model SQL entry point that reuses the existing per-node unordered result comparison. Replace the GROUP BY TAGS test's local comparison loop with this helper, retaining header, value, and duplicate-count checks, and document its use in the IT guide.

Validation

• Spotless and Markdown/license-header/local-link checks passed.
• Targeted clean reactor verification passed on the PR commit with ClusterIT and HighPerformanceMode (1 ConfigNode, 3 DataNodes): 7 tests, 0 failures, 0 errors, 0 skipped.
• Tests: IoTDBTimeDurationIT#testTimeDurationManyColumnOnManyDataRegion and all 6 IoTDBClusterResultSetIT cases, including differing node order and duplicate multiplicity.

mvn -o clean verify -pl integration-test -am \
  -PClusterIT,with-integration-tests -DskipUTs \
  '-Dit.test=IoTDBTimeDurationIT#testTimeDurationManyColumnOnManyDataRegion,IoTDBClusterResultSetIT' \
  -DClusterConfigurations=HighPerformanceMode \
  '-DintegrationTest.includedGroups=org.apache.iotdb.itbase.category.ClusterIT,org.apache.iotdb.itbase.category.TableClusterIT' \
  -DfailIfNoTests=false -Dfailsafe.failIfNoSpecifiedTests=false

This PR has:

• been self-reviewed.
• added documentation for new or modified behaviors.
• added Javadoc for the shared helper.
• modified an existing integration test and been tested in a test IoTDB cluster.

[sonarqubecloud]

Quality Gate failed

Failed conditions
E Reliability Rating on New Code (required ≥ A)

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 47.64%. Comparing base (316c93b) to head (7631362).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #19001      +/-   ##
============================================
+ Coverage     47.63%   47.64%   +0.01%     
  Complexity      806      806              
============================================
  Files          5562     5562              
  Lines        408297   408384      +87     
  Branches      53589    53610      +21     
============================================
+ Hits         194475   194566      +91     
+ Misses       213822   213818       -4     

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