Fine-tuned Gemma 3 4B IT (QLoRA, rank 16) on 640 synthetic credit memo examples for Indian NBFCs. Given a structured borrower profile, the model produces a fully-formatted 6-section credit memo with an APPROVE / CONDITIONAL APPROVE / DECLINE recommendation.

Model Details

Property	Value
Base model	`google/gemma-3-4b-it`
Adapter	`a-anurag1024/rinlekha-gemma3-4b-finetuned`
GGUF	`a-anurag1024/rinlekha-gguf` (Q8_0, 4.1 GB)
Fine-tuning method	QLoRA (4-bit NF4, rank 16, α 32)
Learning rate	1e-4
Epochs	5
Training examples	640
Instruction format	Alpaca

Intended Use

In-scope: Generating draft credit assessment memos for personal/MSME loan applications at Indian NBFCs, following a defined institutional format.
Out-of-scope: Final lending decisions, regulatory compliance, markets outside India, loan amounts beyond the training distribution.

The model is a research prototype. All outputs require human review before use in any real lending workflow.

Training Data

Dataset: a-anurag1024/rinlekha-training-data

800 synthetic borrower profiles generated via stratified sampling (employment type × income band × CIBIL tier × FOIR tier)
Decision labels assigned by a deterministic rule engine matching real NBFC underwriting policy (55% FOIR ceiling, 620 CIBIL floor, settled-account thresholds)
Memos synthesised with GPT-4.1-mini; QC pass filters hallucinations and format violations
Final split: 640 train / 80 validation / 80 test (80/10/10)

Training Procedure

Three-run ablation over rank and learning rate. Best run selected on validation loss:

Run	Rank	LR	Val Loss
run1	8	2e-4	0.847
run2	16	2e-4	0.831
run3	16	1e-4	0.798

Training environment: Unsloth + TRL on Google Colab T4 (15 GB VRAM). LoRA adapter merged via PEFT merge_and_unload() and exported to GGUF Q8_0 via llama.cpp.

Evaluation Results — 100 Test Cases

Metric	Score	Description
StructuralCompliance	1.000	All 6 `## SECTION_NAME` headers present and correctly ordered
RecommendationFormat	1.000	`DECISION / CONDITIONS / RISK GRADE / DECISION AUTHORITY` exact
ForbiddenLanguage	1.000	No certainty language ("definitely", "guaranteed", "will", etc.)
RiskFlagsCount	0.970	Bulleted risk section contains 2–4 grounded flags
Faithfulness	0.961	Figures in memo match the input profile (GPT-4o-mini judge)
GEval	0.832	Overall analytical quality (GPT-4o-mini judge)

Results by decision type:

Decision	n	GEval	Faithfulness
APPROVE	20	0.847	0.946
CONDITIONAL APPROVE	51	0.829	0.969
DECLINE	25	0.824	0.955

Evaluation harness: 6 custom DeepEval metrics (3 rule-based, 1 count-based, 2 LLM-judge via GPT-4o-mini). Results logged to MLflow.

Baseline Comparison — RinLekha vs GPT-4o-mini (30 cases)

GPT-4o-mini is the cost-comparable API baseline — similar inference cost tier to a self-hosted 4B GGUF. Both models receive the same format instructions in the system prompt; any gap on structural metrics reflects format internalization from fine-tuning rather than prompt engineering.

Metric	RinLekha	GPT-4o-mini
StructuralCompliance	1.000	0.994
RecommendationFormat	1.000	1.000
ForbiddenLanguage	1.000	1.000
RiskFlagsCount	0.967	0.133
GEval	0.861	0.863
Faithfulness	0.964	0.940

The most striking gap is RiskFlagsCount (0.967 vs 0.133): GPT-4o-mini consistently produces fewer than 2 or more than 4 bulleted risk flags even with explicit instructions. This is the kind of tight structural constraint that fine-tuning internalizes reliably while prompting does not. GEval (analytical quality) is essentially tied, confirming the 4B model matches a much larger prompted model on reasoning quality for this domain-specific task.

Adversarial Evaluation — 8 Edge Cases

Hand-crafted cases targeting boundary conditions not well-represented in the test set. Decision accuracy: 62% (5/8) — all DECLINE cases correct, misses on CONDITIONAL APPROVE.

Case	Expected	Actual	Result
adv_01 — FOIR 113% post-loan	DECLINE	DECLINE	✓
adv_02 — CIBIL 0, no credit history	CONDITIONAL APPROVE	DECLINE	✗
adv_03 — CIBIL 820 but FOIR 87%	DECLINE	DECLINE	✓
adv_04 — LTI 72×, FOIR 228%	DECLINE	DECLINE	✓
adv_05 — CIBIL 798, only 0.4yr tenure	CONDITIONAL APPROVE	APPROVE	✗
adv_06 — 5 missed payments in 24m	DECLINE	DECLINE	✓
adv_07 — 2 settled accounts	DECLINE	DECLINE	✓
adv_08 — High income, 0.6yr self-employed	CONDITIONAL APPROVE	APPROVE	✗

Adversarial aggregate metrics (format compliance holds even on edge cases): StructuralCompliance 1.000 · RecommendationFormat 1.000 · ForbiddenLanguage 1.000 · RiskFlagsCount 1.000 · GEval 0.853 · Faithfulness 0.959

Failure pattern: the model correctly identifies hard DECLINE signals (FOIR ceiling, settled accounts, delinquency) but conflates CONDITIONAL APPROVE with APPROVE on soft-boundary cases — particularly short employment tenure and unverifiable self-employed income. The training set under-represents these borderline conditions relative to clean approvals.

Usage

python

from llama_cpp import Llama

llm = Llama(model_path="rinlekha-q8.gguf", n_gpu_layers=99, n_ctx=2048)

INSTRUCTION = (
    "You are a senior credit analyst at an Indian NBFC. "
    "Write a structured credit memo for the borrower profile "
    "below following institutional format exactly."
)

prompt = f"### Instruction:\n{INSTRUCTION}\n\n### Input:\n{borrower_profile}\n\n### Response:\n"
out = llm(prompt, max_tokens=700, temperature=0.1, stop=["### Instruction:"])
print(out["choices"][0]["text"])

Or via the OpenAI-compatible server:

bash

# Download GGUF
huggingface-cli download a-anurag1024/rinlekha-gguf rinlekha-q8.gguf --local-dir outputs/

# Start server (llama-cpp-python[server])
python -m llama_cpp.server --model outputs/rinlekha-q8.gguf --host 0.0.0.0 --port 8000 \
  --model_alias rinlekha --n_gpu_layers 99 --n_ctx 2048

Expected Output Format

## APPLICANT SUMMARY
...

## DEBT SERVICEABILITY
...

## CREDIT BEHAVIOR
...

## RISK FLAGS
- Risk flag 1
- Risk flag 2

## RECOMMENDATION
DECISION: CONDITIONAL APPROVE
CONDITIONS: ...
RISK GRADE: B
DECISION AUTHORITY: Branch Credit Manager
REVIEW TRIGGER: ...

## ANALYST NOTES
...

Limitations

Training data is fully synthetic (GPT-4.1-mini authored). The model has not seen real loan files.
The 55% FOIR ceiling and 620 CIBIL floor are hard-coded into the training labels; policy changes are not reflected without retraining.
Max context is 2048 tokens. Very long borrower profiles may be truncated.
The model occasionally generates mild hedged hallucinations in the Analyst Notes section; Faithfulness score of 0.961 reflects this.
Evaluated at temperature 0.1 (near-greedy); higher temperatures degrade format compliance.

Repository

github.com/a-anurag1024/rinlekha