Chroma Hybrid Search

Chroma Hybrid Search Skill

This skill provides local RAG retrieval by combining vector search (semantic) with BM25 keyword search (exact match), followed by Cross-Encoder re-ranking using the BGE-Reranker model. It searches both the hot store (knowledge-base/*.md, experience/*.md) and the cold store (cold-notes/raw.jsonl) — the document set it reads must match what update_db.py indexed, or vectorized cold-store entries would be dropped from results.

Cross-platform command convention — in every command below, <PY> is the virtual-env Python:

• Windows (PowerShell): & "$HOME\.deep-memory\.venv\Scripts\python"
• Linux / macOS: ~/.deep-memory/.venv/bin/python

The venv lives at a fixed absolute path inside the global workspace (~/.deep-memory/.venv), next to the data — commands work from any project directory; no project-local .venv is assumed. On PowerShell keep the & call operator and $HOME (PowerShell does not expand ~ in arguments to native commands); in Git Bash on Windows the same venv is ~/.deep-memory/.venv/Scripts/python.

All skills/... paths assume the skill pack lives inside your current project (project-local install).

Workspace Storage Path Resolution: By default, deep-memory uses the user's global directory ~/.deep-memory (which resolves to C:\Users\<username>\.deep-memory on Windows) to store all knowledge bases, cold notes, and database files. This unifies memories across all your project workspaces.

• If you want to use a specific directory, set the DEEP_MEMORY_WORKSPACE environment variable (e.g., DEEP_MEMORY_WORKSPACE="." or DEEP_MEMORY_WORKSPACE="D:\my-memories").
• You can also pass --workspace <path> to any script to override the workspace path for that specific command.

⚙️ First-Time Initialization (Bootstrap)

When this skill is first invoked by the Agent or user, confirm that the .venv virtual environment and the chroma_hybrid_db vector database have been created and all required packages are installed. If not, execute the following steps:

# 1. Create virtual environment (if it doesn't exist) — fixed location in the global workspace, shared by all projects
#    Windows (PowerShell): python -m venv "$HOME\.deep-memory\.venv"
#    Linux / macOS:        python3 -m venv ~/.deep-memory/.venv

# 2. Install required packages (no activation needed — call the venv Python directly)
<PY> -m pip install -r skills/chroma-hybrid-search/requirements.txt

# 3. Initialize and build the local vector index database
<PY> skills/chroma-hybrid-search/scripts/update_db.py

Notes:

1. Do NOT commit .venv or chroma_hybrid_db/ to GitHub — both live under ~/.deep-memory (outside any repo) and must be generated locally using the steps above.
2. Step 3 is only needed once, to create the index. After that search.py tops it up automatically before every query — see Index Maintenance below.

🔄 Index Maintenance

search.py tops up the index before every query, so update_db.py is no longer part of the daily loop. An indexing failure prints a warning and never blocks the search; --no-auto-index disables the behaviour.

Run update_db.py explicitly only to index new entries immediately rather than at the next search — e.g. right after a refinement pass. update_db.py --rebuild forces every entry to be re-embedded (~6 minutes for a 1,265-entry store); it is only for making vectors correspond exactly to the latest text format, never required for normal operation.

Content-addressed IDs

Cold-store entries are keyed by a semantic hash — cold-notes#<hash12> — not by line number. The hash covers topic / content / tags / skill / memory_type and deliberately excludes date / time / project / quality and every template string. So:

• Deleting or inserting a line anywhere in raw.jsonl does not re-embed the entries after it. Measured on a 928-line store: removing the middle line re-embedded 0 entries — the 463 entries after it only had their line metadata refreshed, at zero embedding cost.
• Marking an entry quality: reviewed during refinement does not trigger a re-embed.
• Changing how the indexed text is assembled does not invalidate the store.

The line number survives in metadata as line and is returned with every cold-store hit, so results stay traceable to their source line.

Run log

Each indexing run appends one JSON line to ~/.deep-memory/logs/index-runs.jsonl with per-stage timings and why entries were re-embedded:

A run that re-embeds more than 20% of the store prints a warning with the reason breakdown. When the reason is id-missing, the usual cause is that the repo copy and the ~/.claude/skills installed copy of kb_reader.py are on different versions — they assemble the indexed text differently, so each sees the other's entries as changed.

🔍 Usage

The Agent can execute scripts/search.py directly from the terminal to perform precise retrieval over the knowledge base and experience store.

1. Hybrid Search + Semantic Re-ranking (Default — Recommended)

Best for complex questions requiring deep semantic understanding:

<PY> skills/chroma-hybrid-search/scripts/search.py --query "spring animation tuning guidelines" --min-score 0.35

Always pass --min-score 0.35 in this mode — besides filtering noise, it lets the project-first pass fall back to the full cross-project store when the current project only has low-relevance hits (without it, a near-zero-score project hit still counts as "found something" and blocks the fallback).

2. Vector Similarity Search Only

Best for cross-language or fuzzy semantic search:

<PY> skills/chroma-hybrid-search/scripts/search.py --query "Spring Boot 404" --mode vector

3. BM25 Keyword Search Only

Best for finding exact proper nouns, variable names, or code snippets:

<PY> skills/chroma-hybrid-search/scripts/search.py --query "pxmin pxmax" --mode bm25

4. Scoped to One Skill, Tag, or Memory Type

Cold-store entries carry skill, tags, and memory_type metadata; experience/skill-[skill-id].md files carry skill derived from their filename, and hot-store entries are tagged as knowledge or experience by source folder. Use --skill for an exact skill-id match, --tag to check the tags array (Chroma's native $contains, requires chromadb ≥1.5.0 — already pinned in requirements.txt), and --memory-type to separate general knowledge from skill/tool experience. These filters narrow the BM25 corpus and the vector where clause identically, so every retrieval method sees the same filtered candidate set:

<PY> skills/chroma-hybrid-search/scripts/search.py --query "session timeout" --skill backend-dev
<PY> skills/chroma-hybrid-search/scripts/search.py --query "config drift"     --tag redis
<PY> skills/chroma-hybrid-search/scripts/search.py --query "agent browser fill fallback" --memory-type experience

Plain knowledge-base/*.md category files have no single skill/tag (they mix many topics), so they're never included by --skill or --tag filters unless the indexed entry explicitly has that metadata; they do participate in --memory-type knowledge.

📋 Output Format

The script outputs a standard JSON array. path for hot-store hits is file.md#entry-slug — one ## 🔧 entry, not the whole file (see "Entry-Level Chunking" below). Use the text field directly as context — do not separately open the file at path with the Read tool. Stripping the #entry-slug and reading the whole source file re-introduces exactly the whole-file dilution chunking exists to avoid; path is for citation (telling the user where a fact came from), not an instruction to read further.

[
  {
    "path": "experience/skill-remotion-best-practices.md#fps-30-causes-av-desync",
    "rerank_score": 0.9402,
    "text": "## 🔧 FPS 30 causes A/V desync\n**Date:** ...\n(just this one entry, not the rest of the file)"
  }
]

✂️ Entry-Level Chunking

knowledge-base/*.md and experience/*.md are indexed per ## 🔧 entry, not per file — kb_reader.py's split_entries() splits on that heading and gives each entry a stable slug (from its title, de-duplicated within the file) so results point to the specific matching entry. A file with no ## 🔧 headings at all falls back to whole-file indexing for backward compatibility. update_db.py and search.py both import this splitting logic from the same kb_reader.py — if you ever need to change how entries are parsed, change it there once, not in both scripts.

🛡️ Anti-Hallucination RAG Routing Guide

• Filename-first matching: If the user's question explicitly mentions a filename, read that file's full content directly via Python glob or fast text search first.
• Tiered RAG: Prioritize filename matching; fall back to search.py hybrid search + rerank only if no match is found.
• Score threshold filtering: Do not pass any chunks or files with a Rerank Score below 0.35 to the model — this prevents noise from degrading response quality. Apply it search-side with --min-score 0.35 rather than filtering the output afterwards: the search-side filter is also what allows the project-first pass to fall back to the cross-project store when project hits are all low-relevance.