[PYF-260] Add flink statement result list command and display results on create --wait

[Zander Matheson (awmatheson)]

Summary

• Add new confluent flink statement result list <statement-name> command that fetches and displays SQL statement result rows from the Flink Gateway API
  • Supports --output human/json/yaml, --wait, and --max-rows flags
  • Rejects unbounded/streaming queries with a clear error directing users to the Flink shell
• Enhance confluent flink statement create --wait to automatically fetch and display results for bounded queries (e.g. SHOW DATABASES), falling through to existing metadata output for DDL statements and unbounded queries
• Cloud-only for now; on-prem (CMF) support can follow in a separate change

Test plan

• go build ./... compiles successfully
• New TestFlinkStatementResultList integration tests pass (human, JSON, YAML, failed, pending, no-results, unbounded)
• Existing TestFlinkStatementCreate tests pass (including --wait)
• Existing TestFlinkStatement tests pass (2 pre-existing failures unrelated to this change)
• Help golden tests pass for both cloud and on-prem
• Golden fixture files created for all output formats, edge cases, and help text
• Manual test with live compute pool: SHOW DATABASES, SHOW TABLES, DDL, JSON/YAML output, --max-rows truncation
• Manual test confirmed unbounded streaming queries no longer hang

Test & Review

Integration tests cover 7 scenarios:

1. Happy path - bounded results in human table format
2. JSON output format
3. YAML output format
4. Failed statement - returns error with status detail
5. Pending statement - returns error suggesting --wait
6. No results (DDL) - prints "Statement has no results to display."
7. Unbounded statement - returns error directing to Flink shell

Manual testing performed against live Confluent Cloud with SHOW DATABASES, SHOW TABLES, CREATE TABLE (DDL), and streaming SELECT queries.

Checklist

• I have successfully built and used a custom CLI binary, without linter issues from this PR.
• I have clearly specified in the What section below whether this PR applies to Confluent Cloud, Confluent Platform, or both.
• I have verified this PR in Confluent Cloud pre-prod or production environment, if applicable.
• I have verified this PR in Confluent Platform on-premises environment, if applicable.
• I have attached manual CLI verification results or screenshots in the Test & Review section below.
• I have added appropriate CLI integration or unit tests for any new or updated commands and functionality.
• [ x I confirm that this PR introduces no breaking changes or backward compatibility issues.
• [ x I have indicated the potential customer impact if something goes wrong in the Blast Radius section below.
• I have put checkmarks below confirming that the feature associated with this PR is enabled in:
  • Confluent Cloud prod
  • Confluent Cloud stag
  • Confluent Platform
  • Check this box if the feature is enabled for certain organizations only

What

Adds non-interactive result fetching for bounded Flink SQL statements. This enables scripting and automation use cases like listing catalogs, databases, and tables via Flink SQL from the command line, which were previously only possible through the interactive Flink shell (REPL).

Key design decisions:

• Uses traits.GetIsBounded() from the Flink Gateway API to distinguish bounded (snapshot) queries from unbounded (streaming) queries
• Bounded queries: results are fetched with pagination up to --max-rows (default 100)
• Unbounded queries: result list returns an error; create --wait falls through to metadata output
• result sub-command registered only for cloud login (on-prem can be added later with a separate child command)

Blast Radius

• Low risk. This is a new additive command (flink statement result list) with no changes to existing command behavior
• The only modification to existing behavior is flink statement create --wait, which now additionally displays results for bounded queries instead of only showing metadata. Unbounded queries and DDL statements behave exactly as before
• Cloud-only; no impact to Confluent Platform users

References

• PYF-260

[confluent-cla-assistant]

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[Zander Matheson (awmatheson)]

Cynthia Qin (@cqin-confluent) thank you for the feedback, I believe it should all be addressed now. I also added some tests for the behavior (like max rows negative).

[Florian Eiden (fleidcc)]

Looking forward to see this in prod :)

[Cynthia Qin (cqin-confluent)]

Looks good to me, left one nit comment