opencode-rag query crashes: "Cannot read properties of undefined (reading 'optimized')" in dedupeSimilar

[haitaur-htr]

Summary

opencode-rag query fails intermittently with:

Query failed: Cannot read properties of undefined (reading 'optimized')
    at dedupeSimilar (dist/retriever/context-optimizer.js:129:46)
    at optimizeContext (dist/retriever/context-optimizer.js:182:21)

Root cause

In dedupeSimilar (dist/retriever/context-optimizer.js), when two chunks from the same file are similar (Jaccard similarity > similarityThreshold) and the higher-scored chunk sits at a higher index than the lower-scored one:

const [keepIdx, removeIdx] = kept[i].score >= kept[j].score ? [i, j] : [j, i];
const removedId = kept[removeIdx].chunk.id;
kept.splice(removeIdx, 1);      // shifts every element down by one
kept[keepIdx] = { ...kept[keepIdx], ... };   // <-- kept[keepIdx] is undefined -> crash

When removeIdx < keepIdx, the splice shifts the keeper down, so kept[keepIdx] is undefined and reading .optimized throws.

Suggested fix

Build the keeper before splicing and adjust the index after removal:

const [keepIdx, removeIdx] = kept[i].score >= kept[j].score ? [i, j] : [j, i];
const removedId = kept[removeIdx].chunk.id;
const keeper = {
    ...kept[keepIdx],
    optimized: {
        ...kept[keepIdx].optimized,
        dedupedFrom: [
            ...(kept[keepIdx].optimized?.dedupedFrom ?? []),
            removedId,
        ],
    },
};
if (removeIdx < keepIdx) {
    kept.splice(removeIdx, 1);
    kept[keepIdx - 1] = keeper;
} else {
    kept[keepIdx] = keeper;
    kept.splice(removeIdx, 1);
}

Repro

• opencode-rag 1.22.0
• opencode-rag query "authentication middleware" in a workspace whose index contains near-duplicate chunks from the same file — crashes every time; simple queries (e.g. opencode-rag query "test") work fine
• Verified locally that the fix restores results for previously-crashing queries and dedup bookkeeping is preserved (dedupedFrom accumulates correctly)