Add Greptile rule to flag missing databricks CI tag on test changes

[amahussein]

Description

Databricks pre-merge CI is conditional — it runs only when the PR title has [databricks] or the diff touches a *db* shim path (per jenkins/Jenkinsfile-blossom.premerge). So a test change that's correct on vanilla Spark but diverges on the Databricks fork (filesystem/path semantics, or optimizer plan-string assertions) can merge green, then resurface as a failure on an unrelated PR that later carries [databricks].

This adds a Greptile nudge to catch those cases at review time:

• .greptile/config.json: new databricks-ci-tag rule, scoped to integration_tests/** and tests/** (severity medium), recommending [databricks] when a test change looks DBR-divergent and the title lacks it. Skips *db*-shim and doc-only changes to avoid noise.
• .greptile/rules.md: focused H9 "Databricks coverage" checklist item.
• AGENTS.md: document when [databricks] is needed, not just how.

Advisory only — it does not gate merges. No user-facing change.

Checklists

Documentation

• Updated for new or modified user-facing features or behaviors
• No user-facing change

Testing

• Added or modified tests to cover new code paths
• Covered by existing tests
  (Please provide the names of the existing tests in the PR description.)
• Not required

Performance

• Tests ran and results are added in the PR description
• Issue filed with a link in the PR description
• Not required

[greptile-apps]

Greptile Summary

This PR adds a Greptile advisory rule (databricks-ci-tag) to nudge reviewers when an integration test change could behave differently on Databricks but the PR title lacks [databricks] — closing a gap where DBR-only failures slip through standard Linux pre-merge CI.

• .greptile/config.json: New rule scoped to integration_tests/** covering filesystem/path semantics and optimizer/plan-string divergence categories; advisory only, does not gate merges.
• .greptile/rules.md: Old H7 trimmed (DB mention moved out) and new H9 added with the Databricks coverage checklist item.
• AGENTS.md: PR title tags bullet expanded with precise auto-trigger conditions and concrete examples (DBFS paths, abfss, os.walk, plan rendering) so contributors know when to add [databricks] manually.

Confidence Score: 5/5

Config/documentation-only change with no user-facing or runtime impact; safe to merge.

All three files are advisory configuration and documentation. The new rule is correctly scoped to integration_tests/**, its inline rationale (Databricks CI only runs Python integration tests, never Scala unit tests) is accurate and consistent across all three changed files, and the change cannot break any existing functionality.

No files require special attention.

Important Files Changed

Filename	Overview
.greptile/config.json	Adds databricks-ci-tag rule (id, rule text, scope integration_tests/**, severity medium) to the Greptile rule set; advisory only, no enforcement.
.greptile/rules.md	Splits the old H7 (which bundled databricks mention) into a focused H7 (non-DB CI gaps) and a new H9 (Databricks coverage); text is consistent with config.json rule and AGENTS.md.
AGENTS.md	Expands the PR title tags bullet with precise conditions for when Databricks CI auto-runs versus needing a manual [databricks] tag, including concrete filesystem and plan-string examples.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[PR submitted] --> B{Diff touches db shim\nor databricks path?}
    B -- Yes --> C[Databricks CI auto-triggers]
    B -- No --> D{PR title has databricks tag?}
    D -- Yes --> C
    D -- No --> E{Diff touches integration_tests?}
    E -- No --> F[Standard Linux pre-merge only]
    E -- Yes --> G{DBR-divergent test?\nfilesystem or plan-string semantics?}
    G -- No --> F
    G -- Yes --> H[H9 advisory: recommend adding databricks tag]
    H --> I[Contributor adds tag or confirms DB coverage]
    I --> C
    C --> J[Databricks pre-merge: DskipTests + Python integration tests]

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_{Reviews (2): Last reviewed commit: "Add Greptile rule to flag missing [datab..." | Re-trigger Greptile}

[amahussein]

build

[amahussein]

build

[nartal1]

LGTM.

[amahussein]

build