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Why

FlightStream replaced dictionary values when a message contained a delta. Valid later indices then failed. This fixes the shared receive path for BDX-1590.

What changed

• Append Flight dictionary deltas through the existing vector appender.
• Extend Null vector counts and refuse count overflow before mutation.
• Add framed Flight regressions and direct vector boundary tests.

Scope

This covers the Arrow library correction. Dremio's coherent Arrow19 build, complete binding transport and compiler, receive limits, Cloud validation, and DaaS remain separate required work. BDX-1590 is incomplete.

Blast Radius

Client DoGet and DoExchange and server DoPut and DoExchange share the corrected branch. Replacement, ordinary streams, errors, cancellation, and ownership have explicit behavioral coverage.

Verification

• The same real-message regression fails on predecessor jars and passes all10 cases on the committed jars. The independent Null probe decodes index1 and closes with zero allocation.
• Vector suites pass39 distinct tests under each of two allocators,78 executed passes. Full Flight Core has156 total cases,139 passes and17 unchanged skips.
• Checkstyle, Error Prone, Spotless, license, dependency and banned-dependency checks pass. Fresh independent source, artifact and behavior review passes.

Exact commands, source and loaded-archive hashes, raw XML and independent review are preserved in the local program run under workstreams/BDX-1590/arrow-null-delta-repair and workstreams/BDX-1590/review-86fbde3be199.md.

The original Dremio19.1 dependency remains unchanged. These Arrow20 test artifacts do not establish Dremio or DaaS acceptance. Production activation is outstanding.