fix(kafka): stabilize record-read setup after W43 merge

[ammarheidari]

Authority

Post-merge verification remediation under W43 issue #157 and tracker #146. W43 implementation PR #159 merged as protected main@714f5e8d41dc001cb4ca3298bdacc1c4a68fe815, but push kafka-smoke #36142114999 failed twice on pre-existing read-only record-reader setup with Kafka is temporarily unavailable.

No v0.6 release/tag/OCI publication is authorized.

Evidence

• PR fix(v0.6): complete W43 SCRAM admission contract #159 exact source head 1dc96474ca0b2526e9a38678c86fe3997f82a7a3 and merge commit 714f5e8d41dc001cb4ca3298bdacc1c4a68fe815 have no file diff.
• PR-head kafka-smoke #36133795062 was successful.
• Post-merge kafka-compatibility #36142115013 is successful on 4.3.1 / 4.2.1 / 4.1.2 / 3.9.2.
• Post-merge smoke attempt 1 failed in Bounded_record_reader_supports_earliest_timestamp_previous_and_out_of_range.
• Rerun attempt 2 failed in a different test, Raw_byte_budget_stops_before_exposing_oversize_record.
• Both failures surfaced the same mapper-approved retryable Unavailable class during initial record-read setup.

Remediation

Exact source head: ccbdf37307df169e9ef279427a35b524bbc77041.
Base: main@714f5e8d41dc001cb4ca3298bdacc1c4a68fe815.

• retry only KafkaFailureMapper-approved retryable Unavailable errors during read-only watermark/timestamp setup;
• keep retry bounded by existing operation deadline and record-read budget;
• add a short cancellation-aware pause for immediate transport/all-brokers-down failures;
• keep authentication/configuration/protocol failures fail-fast;
• do not alter mutation, dispatch, ambiguity or external-effect retry semantics;
• add regression tests for watermark recovery, timestamp recovery and non-retry of authentication failure.

Admission

Merge only after fresh exact-head applicable CI succeeds, substantive review is complete, required threads are resolved, fresh current-head CODEOWNER approval from akhiabanchian exists, mergeability/ruleset are satisfied, and expected-head guarded merge is used.

After merge, re-run post-merge smoke/compatibility and close #157 only when protected-main verification is green.

Refs #157 #146 #159.

[ammarheidari]

@codex review

Please review exact head c088525f56a64bbde7ed627a9384a17aa1747949. Focus on bounded read-only retry semantics, deadline/cancellation behavior, fail-fast authentication/config/protocol handling, and any risk of broadening retry into mutation paths.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-25T13:53:55.307026Z	ccbdf37	Manual request

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[ammarheidari]

@codex review

Fresh exact-head review requested for 11fdaca811c4fa2409118635fb17d2ad706671b4 after the timestamp regression-test compile correction. Re-check bounded read-only Unavailable retry semantics, cancellation/deadline behavior, and fail-fast non-retryable errors.

[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: 11fdaca811

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[ammarheidari]

@codex review

Please review fresh exact head ccbdf37307df169e9ef279427a35b524bbc77041 after capping setup Unavailable backoff to recomputed live operation/budget remaining time and adding budget-exhaustion regression coverage.

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. 👍

Reviewed commit: ccbdf37307

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