Ollama-adapter - Groundedness check validates `evidence_refs` against the *untrimmed* evidence object, not the trimmed evidence actually sent to the model

[tarunkumartiwary1]

Summary

Same defect as the three sibling adapters (llm-anthropic, llm-openai, llm-gemini, filed separately), present here too:

const contextLimit = getContextLimit(this.provider, this.model);
const { evidence: trimmedEvidence, trim } = trimEvidenceForContext(evidence, contextLimit);

const systemPrompt = buildSystemPrompt();
const userPrompt = buildUserPrompt(trimmedEvidence, question);   // model sees trimmedEvidence

let payload = await callOllama({
  ...
  messages: [
    { role: "system", content: systemPrompt },
    { role: "user", content: userPrompt },
  ],
  ...
});

...

const grounding = validateEvidenceGrounding(evidence, evidenceRefs);
//                                           ^^^^^^^^ should be trimmedEvidence

Why this matters

userPrompt is built from trimmedEvidence, which trimEvidenceForContext (packages/llm/llm-core/src/context.ts) can shrink by removing evidence items, what_changed entries, or similar-incident entries in order to fit the (often much smaller) context windows typical of locally-hosted Ollama models — this is actually the adapter most likely to trigger trimming in practice given PROVIDER_DEFAULT_CONTEXT_LIMITS.ollama = 8192 in packages/llm/llm-core/src/token-usage.ts. Despite that, validateEvidenceGrounding is called with the full, untrimmed evidence.

Since validateEvidenceGrounding (packages/llm/llm-core/src/grounding.ts) only checks evidence_refs for id membership in evidence.evidence, and trimmedEvidence.evidence ⊆ evidence.evidence, an evidence_refs id corresponding to an item that was trimmed out (and thus never appeared in userPrompt) can still be classified "grounded". Given local models are already the most failure-prone target for this adapter's forced-JSON retry path, this is exactly the adapter where an accurate hallucination signal matters most, and it's the one most likely to actually hit the trimming path in real usage.

Suggested fix

const grounding = validateEvidenceGrounding(trimmedEvidence, evidenceRefs);

File:

packages/llm/llm-ollama/src/ollama-adapter.ts