AIR CLI Integration: fall back to MLflow when Bricklens returns no logs for a terminal run

[riddhibhagwat-db]

Changes

air logs <run> printed "No logs available for run . Run terminated in state SUCCESS" and exited 0 for runs whose logs were fully retrievable: air logs --download-to DIR on the same run returned the complete log. This happens when Bricklens is enabled for the workspace but never ingested the run so it answers every request successfully with zero records, yet the logs are present in MLflow.

The streaming (print) path only fell back to MLflow on errBricklensFeatureDisabled (gated off / not deployed / persistent failure); an empty-but-successful Bricklens response was treated as the final answer. The download path already reads from MLflow, which is why it worked.

This is the Go version of the Python fix: https://github.com/databricks-eng/universe/pull/2384942

Tests

1. TestStreamBricklensEmptyFallsBackToMLflow:

• terminal run — a TERMINATED/SUCCESS run whose Bricklens /logs returns {"log_records": []} must make streamBricklensLogs return errBricklensFeatureDisabled and emit nothing (so the caller falls back to MLflow rather than printing "No logs available").
• static view of a past retry — same assertion for the staticView: true path.

2. TestStreamBricklensTerminalWithRecordsDoesNotFallBack: the guard against over-eager fallback: a terminal run whose Bricklens stream does have a record prints it ("line":"hello"), returns true, no error — confirming the fallback only fires on a genuinely empty stream.
3. TestFetchLogsFallsBackToMLflowWhenBricklensEmpty: the end-to-end reproduction of your bug: one fake server serving empty Bricklens /logs plus a populated MLflow path (runs/get → get-output → artifacts/list → credentials-for-read → presigned chunk download). Asserts fetchLogs returns success and the two MLflow log lines (line 1, line 2) reach stdout — i.e. the print path now behaves like --download-to

[eng-dev-ecosystem-bot]

Integration test report

Commit: 9d8e92a

Run: 31642925843

	Env	💚​RECOVERED	🙈​SKIP	✅​pass	🙈​skip	Time
💚​	aws linux	4	4	291	1104	4:08
💚​	aws windows	4	4	293	1102	2:58
💚​	azure linux	4	4	290	1104	4:27
💚​	azure windows	4	4	292	1102	3:51
💚​	gcp linux	1	5	291	1104	4:42
💚​	gcp windows	1	5	293	1102	4:30

8 interesting tests: 4 RECOVERED, 4 SKIP

	Test Name	aws linux	aws windows	azure linux	azure windows	gcp linux	gcp windows
💚​	TestAccept	💚​R	💚​R	💚​R	💚​R	💚​R	💚​R
🙈​	TestAccept/bundle/invariant/no_drift	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S
🙈​	TestAccept/bundle/resources/vector_search_endpoints/drift/recreated_same_name	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S
🙈​	TestAccept/bundle/resources/vector_search_indexes/recreate/embedding_dimension	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S
🙈​	TestAccept/ssh/connection	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S	🙈​S
💚​	TestFetchRepositoryInfoAPI_FromRepo	💚​R	💚​R	💚​R	💚​R	🙈​S	🙈​S
💚​	TestFetchRepositoryInfoAPI_FromRepo/root	💚​R	💚​R	💚​R	💚​R
💚​	TestFetchRepositoryInfoAPI_FromRepo/subdir	💚​R	💚​R	💚​R	💚​R

Top 1 slowest tests (at least 2 minutes):

duration	env	testname
2:34	azure windows	TestAccept

[vinchenzo-db]

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