[guyroyse]

Problem

Combiner.addParams serializes the COMBINE <method> <count> clause using only the method-specific tokens (WINDOW/CONSTANT/ALPHA/BETA). When a combined-score alias is set via .as(...), the appended YIELD_SCORE_AS <alias> tokens fall outside that count, so Redis reads past the clause and rejects the command with YIELD_SCORE_AS: Unknown argument. Any hybrid query setting a combined-score alias fails.

For example, Combiners.rrf().window(20).constant(60).as("score") emitted:

COMBINE RRF 4 WINDOW 20 CONSTANT 60 YIELD_SCORE_AS score

when Redis expects the count to cover all six following tokens:

COMBINE RRF 6 WINDOW 20 CONSTANT 60 YIELD_SCORE_AS score

Fix

Include the two YIELD_SCORE_AS <alias> tokens in the count when an alias is present. Since addParams is final on the shared base Combiner, this covers both RRF and LINEAR combiners.

Tests

Adds CombinersTest with protocol-level serialization coverage for both combiners — each parameter alone and combined, the empty default, and the YIELD_SCORE_AS alias cases that regress this bug. Follows the existing CommandArgumentsMatchers idiom (hasArgumentCount / hasArguments). Verified the existing FTHybridRedisClientCommandsIT still passes against a live Redis.

Introduced by #4405.

Fixes #4574

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Note

Low Risk
Small, targeted fix to search command serialization with broad unit and integration test coverage; no auth, data, or API contract changes beyond correcting broken hybrid queries that use .as(...).

Overview
Fixes FT.HYBRID hybrid queries that set a combined-score alias via Combiner.as(...). Redis expects the COMBINE <method> <count> count to cover every token in the clause, including YIELD_SCORE_AS and the alias; the client previously counted only method-specific args, so Redis treated those tokens as unknown arguments and rejected the command.

Combiner.addParams now adds 2 to the clause count when a score alias is present, so both LINEAR and RRF combiners serialize correctly.

Adds CombinersTest for command serialization (defaults, parameters, and alias cases) and a parameterized integration test in FTHybridCommandsTestBase that asserts the combined score is returned under the alias.

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