[hughhhh]

SUMMARY

Partition preview messages could describe a throttled request or NULL output as a broken transform, claim an invalid expression was already saved, or omit the next step for a missing placeholder or incompatible output type. This change distinguishes those outcomes, offers an explicit retry for unavailable previews, and moves keyboard focus to the transform input after moving a mapping.

It also catches unmatched nested parentheses before warehouse probes and uses readable Hive partition-filter errors in Samples and drill-to-detail. Existing save eligibility, emitted predicates, transform defaults, and cached verdict semantics are preserved.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

• HTTP 429: “Filters will not be mirrored” → “Preview temporarily unavailable,” with a Retry button.
• NULL output: generic evaluation failure → an explanation that one or more preview values returned NULL.
• Move mapping: focus falls off the removed button → focus lands in Value transform.
• Hive strict mode: raw TExecuteStatementResp(...) → guidance to add a suitable partition filter.

TESTING INSTRUCTIONS

Proof: 642 backend tests and 144 frontend tests pass; staged-file pre-commit checks pass, including mypy and frontend typechecking. Ten new or strengthened backend assertions fail against the unchanged base. Headless Chromium exercised the actual mapping component with controlled HTTP responses and verified focus transfer, accessible placeholder guidance, throttling, and successful retry without page errors.

With PARTITION_FILTER_MAPPING enabled:

1. Preview extract(epoch from cast(:value as timestamp) and lower(:value), 'x': expect syntax guidance without a warehouse probe or a claim that the mapping was saved.
2. Preview NULL-producing and incompatible-type transforms: expect distinct NULL and cast guidance. Enter a nonempty transform without :value: expect a nonblocking field warning.
3. Throttle the preview endpoint: expect an unavailable-preview warning, then successful recovery through Retry.
4. Activate “Move mapping to this column” with Enter or Space: continue typing directly in Value transform.
5. On Hive strict mode, open Samples or drill detail without a partition filter: expect a readable error. A working filtered request should still succeed.

The Hive driver error shapes are covered by regression tests; a live Hive warehouse was not available for this run.

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags: PARTITION_FILTER_MAPPING
• Changes UI
• Includes DB Migration
• Introduces new feature or API: additive preview diagnostic reason null_result
• Removes existing feature or API

Reviewed with sol-loop: 1 round with GPT-6.1 Sol. Sol verdict: approved.

Created with GPT-6 Astra in T3 Code through the Codex harness.

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[codeant-ai-for-open-source]

  CodeAnt PR Risk

🟢  Low Risk

• The PR appears safe to merge; no actionable issues were identified in the review.

Assessed commit: fa83d9f0f62c

[codecov]

Codecov Report

❌ Patch coverage is 98.57143% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 84.77%. Comparing base (7519fa8) to head (fa83d9f).

Files with missing lines	Patch %	Lines
superset/connectors/sqla/partition_mapping.py	93.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #45833      +/-   ##
==========================================
+ Coverage   84.76%   84.77%   +0.01%     
==========================================
  Files        3072     3072              
  Lines      206119   206235     +116     
  Branches    48539    48570      +31     
==========================================
+ Hits       174718   174842     +124     
+ Misses      28101    28092       -9     
- Partials     3300     3301       +1     

Flag	Coverage Δ
hive	34.48% <18.60%> (-0.01%)	⬇️
javascript	81.08% <100.00%> (+0.02%)	⬆️
mysql	52.59% <27.90%> (-0.02%)	⬇️
postgres	52.60% <27.90%> (-0.02%)	⬇️
presto	36.21% <9.30%> (-0.01%)	⬇️
python	87.77% <97.67%> (+<0.01%)	⬆️
sqlite	52.35% <23.25%> (-0.02%)	⬇️
unit	82.53% <97.67%> (+<0.01%)	⬆️

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