Etsu-Embedding-0.8B

Name: Etsu โ€” from the Japanese reading of ไผš้€š (etsลซ), the Buddhist term for the convergence of disparate teachings. From Zheng Qiao's (้ƒ‘ๆจต) Tongzhi (ใ€Š้€šๅฟ—ยทๆ€ปๅบใ€‹):

็™พๅทๅผ‚่ถ‹๏ผŒๅฟ…ไผšไบŽๆตท๏ผŒ็„ถๅŽไนๅทžๆ— ๆตธๆทซไน‹ๆ‚ฃ๏ผ›ไธ‡ๅ›ฝๆฎŠ้€”๏ผŒๅฟ…้€š่ฏธๅค๏ผŒ็„ถๅŽๅ…ซ่’ๆ— ๅฃ…ๆปžไน‹ๅฟงใ€‚ไผš้€šไน‹ไน‰ๅคง็Ÿฃๅ“‰๏ผ

A hundred rivers run different courses, yet all must reach the sea; ten thousand states take different roads, yet all converge upon the Central States โ€” great indeed is the meaning of huitong (convergence). An embedding model does the same: it maps heterogeneous inputs into one shared vector space.

An embedding model fine-tuned from Qwen/Qwen3.5-0.8B-Base for agent memory retrieval and related domain-specific semantic retrieval.

Model Overview

  • Model Type: Text Embedding
  • Supported Languages: Chinese, English
  • Number of Parameters: 752M (752,393,024)
  • Context Length: 2048 tokens
  • Embedding Dimension: 1024 (supports MRL dimensions 128, 256, 512, 768, 1024)

Model Details

Property Value
Base model Qwen/Qwen3.5-0.8B-Base
Architecture Qwen3.5 hybrid text model
Layers 24 (18 linear-attention + 6 full-attention)
Hidden size 1024
Intermediate size 3584
Vocabulary size 248,320
Embedding output 1024 dimensions
Pooling Last-token pooling
Normalization L2 normalization
Similarity Cosine similarity or normalized dot product
Training precision BF16
MRL dimensions 128, 256, 512, 768, 1024
License Apache-2.0

Intended Use

Chinese/English semantic retrieval for agent memory, personal knowledge bases, conversation archives, technical documentation, and related domain-specific search, including short keyword queries and natural questions.

Encoding Protocol

Queries:

Instruct: Given a query, retrieve relevant passages that answer the query
Query: {query}

Memories/passages: no instruction prefix.

Use last-token pooling and L2 normalization. If using Matryoshka truncation, truncate to 128, 256, 512, or 768 dimensions before the final L2 normalization.

This is not a sentence-transformers package with a built-in pooling wrapper; implement the pooling and query prefix as described above.

Comparison with Qwen/Qwen3-Embedding-0.6B

S2 is this model; Official is Qwen/Qwen3-Embedding-0.6B. Values are Recall@K or MRR. The same tokenizer protocol, query instruction, pooling, normalization, corpus, and query set were used per row.

OpenClaw fine-tuning validation

Dim S2 R@1 Official R@1 S2 R@3 Official R@3 S2 R@5 Official R@5 S2 R@10 Official R@10 S2 MRR Official MRR
128 8.96% 17.19% 19.57% 31.84% 25.82% 37.98% 35.32% 46.49% 17.57% 27.38%
256 15.04% 20.12% 30.74% 35.99% 38.58% 43.67% 50.14% 52.35% 26.46% 31.25%
512 21.67% 22.33% 40.57% 39.19% 49.75% 47.21% 62.02% 57.16% 34.84% 34.11%
768 23.88% 22.94% 44.67% 40.57% 53.45% 48.31% 65.06% 58.71% 37.60% 34.97%
1024 25.21% 23.66% 45.55% 41.46% 54.62% 49.36% 66.56% 59.92% 38.86% 35.66%

Unseen memory

Corpus of 382 memory chunks dated after 2026-08-08; 1,048 Gemini-generated queries with multi-positive qrels where applicable.

Dim S2 R@1 Official R@1 S2 R@3 Official R@3 S2 R@5 Official R@5 S2 R@10 Official R@10 S2 MRR Official MRR
128 12.02% 18.80% 26.15% 40.55% 35.50% 49.43% 47.81% 59.73% 23.76% 33.14%
256 17.08% 20.32% 35.40% 43.89% 45.99% 51.91% 61.83% 62.02% 31.00% 35.07%
512 20.42% 23.09% 43.23% 45.32% 54.87% 54.10% 68.61% 63.93% 36.48% 37.40%
768 21.56% 22.04% 45.80% 45.80% 59.06% 54.39% 72.23% 63.84% 38.22% 36.91%
1024 22.33% 21.09% 46.47% 45.52% 58.59% 53.91% 72.04% 64.31% 38.80% 36.25%

Conventional content validation sample

Stratified sample of 382 queries from the pretraining validation split, with 761 unique positive/negative passages.

Dim S2 R@1 Official R@1 S2 R@3 Official R@3 S2 R@5 Official R@5 S2 R@10 Official R@10 S2 MRR Official MRR
128 80.37% 81.41% 93.46% 93.19% 96.60% 96.34% 98.43% 97.91% 87.45% 87.93%
256 87.70% 85.86% 96.60% 93.98% 98.43% 96.34% 99.74% 97.64% 92.42% 90.43%
512 89.53% 85.34% 97.91% 93.72% 99.21% 96.34% 99.74% 98.43% 93.71% 90.22%
768 91.10% 84.82% 97.64% 95.03% 99.21% 97.38% 99.74% 98.69% 94.58% 90.34%
1024 91.36% 84.29% 97.64% 95.29% 98.95% 97.12% 99.74% 98.69% 94.74% 90.13%

Recommendations

  • OpenClaw's default memory search returns up to 10 results, so Recall@10 is the primary metric.
  • Use 1024 dimensions for maximum ranking quality, especially when top-1/top-3 and MRR matter.
  • Use 768 dimensions as the storage/Recall@5-10 compromise; it uses about 25% less vector storage than 1024 dimensions.

Training Data Disclosure

The model was trained on Chinese retrieval data assembled from two public datasets, combined, deduplicated and shuffled (ensure_data() in train.py):

Source Rows Fields License / Origin
sentence-transformers/t2ranking (train) 600,000 query / positive / negative HF dataset card
sentence-transformers/dureader (train) 180,000 query / positive / negative HF dataset card
all_nli.jsonl (English NLI) 120,000 sentence pairs, lang: en mixed NLI (see below)

After dedup + shuffle: train.jsonl 889,836 rows, valid.jsonl 8,988 rows (900,000 raw โ†’ 898,824 unique; valid = min(10000, len/100)).

File checksums (SHA-256)

b396d0e0a6bc8cfa362a5dbebc75d39fe34957c451071d4fcc4ad577fa6713cf  t2ranking.jsonl
2bf403211c0f4249a4f3c795c66c09b7d4633fbccb12e1f7331ae76ab535447a  dureader.jsonl
1ec56c99bf9b3d8ff3d9dd373af28ba2c06ffbab9c584b344a4386e57925a71e  train.jsonl
a81323db927859ec05bfe23af70e6c99b3faec4063fc8021767bdb9afe59117a  valid.jsonl
4ca2c0a6e701d95e0a7b1ea31d1f1c78da99d937fa58fa3471e9a3c023a9ce7a  all_nli.jsonl

Benchmark overlap audit (2026-10-17)

Compared against the query/corpus hashes of 8 Chinese retrieval tasks (C-MTEB 7 + mteb/T2Retrieval), covering 867,992 query+passage strings:

  • Query sets: only 3 unique eval queries appear in training (T2Retrieval 2/22,812; DuRetrieval 1/2,000; others 0).
  • Passage (corpus) sets, unique eval passages also present in training:
    • T2Retrieval: 4,016 / 118,605 (3.39%)
    • CovidRetrieval: 984 / 100,001 (0.98%)
    • DuRetrieval: 150 / 100,001 (0.15%)
    • CmedqaRetrieval: 16 / 100,001 (0.02%)
    • MedicalRetrieval: 7 / 100,999 (0.01%)
    • MMarcoRetrieval / EcomRetrieval / VideoRetrieval: 0
  • Overlapping passages come almost entirely from the negative fields (t2ranking โ†’ T2Retrieval corpus 3,953; dureader โ†’ CovidRetrieval 823), i.e. the model saw them as random negatives, not as positive targets. Positive-field overlap is only 282 passages in total.

Interpretation: no meaningful queryโ†’answer leakage; the residual overlap is source-level corpus exposure (same web QA pool), which we disclose here rather than claim a fully clean split. Scores on T2Retrieval/CovidRetrieval should be read with this caveat.

Base Model and License

Derived from Qwen/Qwen3.5-0.8B-Base and distributed under the base model's Apache-2.0 license. Please review the base model license and usage requirements.

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