Add unit tests for hallucination-control scoring (splitSentencesFast, computeHallucControlImprovement)

[deepintai]

Context

The semantic cache plugin computes a hallucination-control "improvement" score (based on hedging language and citation density) that drives a dashboard metric. The two core helpers, splitSentencesFast() and computeHallucControlImprovement(), have no test coverage — the deepintshield_server/plugins/semanticcache/ package has no *_test.go files. Both functions are pure and dependency-free, making them ideal for a first contribution.

What to do

Create deepintshield_server/plugins/semanticcache/hallucination_control_test.go covering:

1. splitSentencesFast(s string) []string (line ~328): sentence boundaries on ., !, ?, and newlines; empty string; single word with no terminator; trailing/leading whitespace.
2. computeHallucControlImprovement(response string) float64 (line ~293):
   • Response full of hedging language vs. one with none.
   • Response with citations (e.g. [source: ...], https://... URLs) vs. none.
   • Mixed hedging + citations.
   • Empty string returns a sane value.
   • Assert the result is always within [0, 1].

Acceptance criteria

• New file deepintshield_server/plugins/semanticcache/hallucination_control_test.go.
• Both functions exercised, including empty/whitespace/single-sentence edge cases.
• Every returned score asserted to be in [0, 1].
• go test ./... for the plugin passes locally with no external dependencies.
• Follows existing Go test conventions used elsewhere in the repo.

File pointers

• Implementation: deepintshield_server/plugins/semanticcache/hallucination_control.go
  • computeHallucControlImprovement at line ~293
  • splitSentencesFast at line ~328
• Test-style reference: deepintshield_server/plugins/guardrails/cache_reuse_test.go