Kwai Keye-VL 1.5: Revolutionizing Video Understanding with Multimodal AI

Introduction: The Challenge of Video Comprehension

How can AI models effectively understand videos while balancing spatial detail and temporal coverage? This fundamental question has challenged researchers for years. Videos present unique difficulties compared to static images—they contain dynamic, information-rich content that requires processing temporal relationships while managing the inherent trade-off between frame coverage and resolution quality.

Kwai Keye-VL 1.5 represents a significant breakthrough in addressing these challenges. Developed by Kuaishou’s Keye Team, this 8-billion parameter multimodal foundation model achieves state-of-the-art performance in video understanding while maintaining robust capabilities across general vision-language tasks. Through three key innovations—an innovative Slow-Fast video encoding strategy, progressive pre-training with extended context length, and comprehensive post-training methodologies—Keye-VL 1.5 sets new standards for what’s possible in multimodal AI.

Core Architecture: Building a Foundation for Advanced Video Processing

What architectural innovations enable Keye-VL 1.5’s superior video understanding capabilities? The model follows a classic multimodal large language model (MLLM) architecture with three crucial components: a Vision Transformer (ViT), an MLP projector, and a language decoder.

The vision encoder utilizes SigLIP-400M-384-14, implementing native dynamic resolution processing that preserves original aspect ratios by dividing each image into a 14×14 patch sequence. This approach maintains structural integrity and preserves all image details during processing. The language decoder employs Qwen3-8B, providing universal world semantic knowledge understanding capabilities. The projector’s parameters are randomly initialized and fully pre-trained during the first stage.

Key Architectural Innovations:

The implementation of 2D Rotary Position Embedding (RoPE) significantly enhances the model’s extrapolation capabilities for positional encoding along visual dimensions. This modification proves particularly valuable for high-resolution image processing. Combined with NaViT packing and FlashAttention techniques, these innovations enable continuous ViT training across images with varying resolutions.

For visual encoding, the model employs different strategies for images and videos:


  • Native-Resolution Image Encoding: Each image receives up to 20,480 tokens (at the LLM side), sufficient to cover images with tens of millions of pixels and ensure detailed understanding

  • Slow-Fast Video Encoding: This novel approach dynamically allocates computational resources based on inter-frame similarity, processing key frames with significant visual changes at higher resolution while handling relatively static frames with increased temporal coverage at lower resolution

Slow-Fast Video Encoding: Intelligent Resource Allocation

How does the Slow-Fast strategy overcome the spatial-temporal trade-off in video processing? This innovative approach addresses one of the most persistent challenges in video understanding by dynamically adapting to content characteristics.

The system identifies slow and fast frames using a patch-based similarity function:

  1. The first frame is always defined as a slow frame
  2. For each subsequent frame, if its patch similarity with the latest slow frame exceeds 95%, it’s marked as a fast frame; otherwise, it becomes a new slow frame

The Slow Pathway processes fewer frames but at higher resolution, capturing detailed visual information from rapidly changing scenes. The Fast Pathway handles more frames at lower resolution, capturing subtle changes from relatively static frames. To balance the trade-off between frame numbers and total token budget, fast frames receive 30% of a slow frame’s token budget.

Practical Implementation:

A binary search technique precisely calculates the number of tokens per slow frame under total token budget limitations (75,000 tokens in Keye-VL 1.5). Additional special tokens and absolute timestamps help the model identify boundaries and temporal information between slow and fast frames during learning.

In real-world applications, this strategy proves particularly effective for content with varying motion dynamics. For sports analytics, the system allocates higher resolution to key moments like scoring events while using efficient processing for continuous player movement. In surveillance footage, it provides detailed analysis of unusual activities while economically processing routine scenes.

Progressive Pre-Training: Building Capabilities Systematically

How does Keye-VL 1.5 develop its robust multimodal capabilities? The model employs a four-stage progressive training strategy that systematically builds vision-language alignment and understanding capabilities.

Stage 1: Cross-Modal Alignment
The vision encoder undergoes continuous pre-training using SigLIP contrastive loss function, adapting to internal data distributions. The language model initializes from Qwen3-8B while both vision and language model parameters remain frozen. Training focuses exclusively on optimizing the projection MLP layer, establishing robust cross-modal feature alignment through large-scale datasets.

Stage 2: Multi-Task Pre-Training
All model parameters unfreeze for end-to-end optimization using diverse multi-task training data. This stage incorporates various vision-language tasks including Image Captioning, OCR, Grounding, VQA, and interleaved image-text data, significantly enhancing fundamental visual understanding capabilities.

Stage 3: Annealing Phase
The model fine-tunes on curated high-quality data, addressing the issue of insufficient exposure to premium samples during large-scale training in Stage 2. Through optimized learning strategies and data mixtures, this stage refines nuanced understanding and capabilities.

Sequence Length Extension to 128K
Stages 1 and 2 limit sequence length to 8,192 tokens using Data Parallelism for large batch sizes and Zero-2 optimization for memory efficiency. The annealing stage extends context length from 8K to 128K tokens, resetting RoPE inverse frequency from 1,000,000 to 8,000,000. The training data enriches with high-quality long-context modalities including long videos, lengthy texts, and large-scale images.

The optimization strategy switches to Zero-1 with Context Parallelism and Pipeline Parallelism to support long-context training. Controlled experiments determine optimal token allocation: 24% for videos, 50% for images, and 26% for text, striking an ideal balance between visual and textual capabilities.

Comprehensive Data Pipeline: Fueling Model Performance

What data strategies support Keye-VL 1.5’s exceptional performance? The training pipeline incorporates a diverse, high-quality corpus exceeding 1 trillion tokens from both public datasets and proprietary internal data.

The data encompasses six primary categories:


  • Image Caption data for fundamental world knowledge mapping

  • OCR & VQA data for detailed image understanding

  • Grounding & Counting data for object localization

  • Interleaved text-image data for long-context modeling

  • Video understanding data for temporal comprehension

  • Pure text data for linguistic capabilities

Quality Assurance Measures:
Customized filtering mechanisms tailored to each data category ensure overall quality. CLIP scores filter large volumes of medium-quality data, while open-source MLLMs select smaller amounts of high-quality data. Rigorous image-based deduplication prevents potential data leakage between training corpus and evaluation benchmarks.

Image Caption Data Enhancement:
Beyond standard caption data, the implementation includes multiple-caption/question-answering pairs to maintain general conversation and instruction capabilities:


  • <image, caption, [eos], question, answer> format trains seamless transition from caption generation to accurate question answering

  • <image, question, answer, [eos], caption> format reverses task order, breaking caption generation tendency

  • Instruction-following image captioning/QA with multiple images and random questions enhances robustness

Proactive injection of ‘trap questions’ referring to non-existent or contradictory elements encourages accurate grounding in visual content rather than textual priors.

OCR & VQA Data Development:
The model incorporates extensive open-source data including LaTeX formulas, handwritten text, real-world street views, charts, rich-text documents, and multi-image OCR. For Chinese OCR enhancement, techniques include:


  • Synthesis with SOTA MLLMs using text-dense images from open-source and internal datasets

  • Font rendering tools creating diverse OCR samples with varied backgrounds, semantic/non-semantic text, multiple font styles/sizes, and different resolutions

  • Structured document and code understanding using Markdown, HTML, and programming languages

  • Instruction-following OCR datasets with character-matrix images and Chinese instructions covering thirteen reading and locating templates

Grounding & Counting Data:
The model utilizes three object localization forms: center points, bounding boxes, and polygons, with coordinates normalized to [0, 1000] for different resolution images. For temporal grounding, a three-step coarse-to-fine-grained data synthesis pipeline processes short videos into event clips with temporal captions, using SOTA MLLMs to filter low-quality outputs and Gemini 2.5 Pro to generate logical question-answering pairs about timestamps.

Interleaved Text-Image Data:
Beyond single-image learning, interleaved data enhances longer multimodal context modeling and sequence adaptation. The pipeline processes academic PDFs and structured knowledge data, particularly STEM content, with rigorous quality control including garbled character recognition, low-resolution image filtering, and text-image similarity validation.

Video Data Processing:
As a short-video and live-streaming service provider, Kuaishou emphasizes video understanding capabilities. Video data collection includes diverse open-source datasets and large-scale high-quality internal video data with key pipelines:


  • Interleaved video-ASR using speech-to-text tools like Qwen2.5Omni

  • Video captioning with various public MLLMs at different FPS settings (0.5/1/2)

  • Frame-level OCR annotation ensuring comprehensive detail capture

  • Reasoning-enhanced tasks including frame-level re-ordering and multiple video matching

Post-Training Methodology: Enhancing Reasoning and Alignment

How does Keye-VL 1.5 achieve its advanced reasoning capabilities and human preference alignment? The post-training process focuses on two critical aspects through a comprehensive pipeline with three key components.

Non-Reasoning Stage: SFT + MPO
The SFT candidate pool contains over 7.5 million multimodal QA samples constructed with balanced comprehensiveness and quality:


  • Task diversity through TaskGalaxy framework covering 70,000 distinct multimodal task types

  • Data challenge through multiple reasoning paths generation and complexity measurement

  • Data reliability through human-annotated image and video captions

Dynamic learning rates with annealing in later phases contribute approximately 1% performance improvement across benchmarks. MPO training utilizes 250k open-source samples, 150k text-only samples, and 26k human-annotated samples, constructing quality pairs using reward model scores and human annotations.

Keye-Reward Model Development
The reward model, based on Keye-VL-preview, supports data filtering and reinforcement learning training. It processes inputs containing query, response A, and response B with task definition guidance, operating in both think and no_think modes similar to Keye-VL-1.5’s mixed reasoning approach.

The no_think mode outputs direct judgments, while think mode evaluates responses across nine dimensions (Credibility, Correctness, Redundancy, Relevance, etc.) before generating comprehensive evaluations. This mixed reasoning approach balances efficiency, accuracy, and interpretability.

LongCoT Cold-Start: Building Reasoning Foundations
After large-scale SFT and MPO, high-quality Long Chain-of-Thought (LongCoT) data enables cold-start reasoning training, enhancing long CoT reasoning ability as the starting point for subsequent reinforcement learning.

The automated five-step pipeline generates LongCoT data:

  1. Multi-source data collection and enhancement across challenging domains
  2. Multi-path reasoning generation with confidence quantification
  3. Comprehensive two-level quality assessment (answer correctness and reasoning process validity)
  4. Human-in-the-loop quality enhancement for intermediate samples
  5. Dynamic quality scoring and data utilization strategy

Samples categorize into three quality tiers:


  • Category A: Both answer and reasoning process correct

  • Category B: Correct final answers with reasoning process issues

  • Category C: Incorrect answers or severely flawed reasoning (discarded)

Human review refines Category B and borderline Category A samples, correcting verbose or redundant reasoning steps while preserving valuable training data. The five-point quality scoring system evaluates samples across multiple dimensions, with adaptive utilization strategies prioritizing higher-quality samples.

Model Merging with Domain Specific Experts
Analysis reveals concentrated weaknesses in pure text processing, mathematical reasoning, and OCR domains. The enhancement strategy involves:


  • Systematic gathering of OCR datasets targeting weak areas (license plates, street signage, official seals)

  • Automated data pipeline generation of relevant OCR questions using verified annotations as ground truth

  • SFT on cold-start model using general and specialized datasets to create expert models

  • Model merging techniques integrating domain-specific experts with the base model

Iterative General RL: Enhancing Reasoning Capabilities
General RL applies GSPO (Group Sequence Policy Optimization) algorithm for RLVR (Reinforcement Learning with Verifiable Rewards) training, using a cyclical iterative approach to enhance both RL and cold-start models.

Training data selection covers mathematics, science & technology problems, logical reasoning & puzzles, code, chart question answering, visual grounding, spatial relationships, and counting. Each data point contains verifiable answers for rule-based reward calculation, with domain proportions adjusted based on ablation experiments.

Progressive Hint Sampling
For difficult samples where the model consistently fails, progressive hint sampling improves success rates. The hierarchical hint system follows Minimal Intervention principle with five levels:

  1. Level 1 (Concept/Observation): Guide focus to core concepts or key features
  2. Level 2 (Strategy/Method): Suggest problem-solving strategies without specific formulas
  3. Level 3 (Tools/Formula): Provide specific mathematical theorems or tools needed
  4. Level 4 (Steps/Calculation): Offer first concrete operational step
  5. Level 5 (Complete Solution): Provide complete, clear final solution

For each hard case, hints progress from low to high levels, with minimal sufficient information used to update policy.

Iterative General RL & Cold-Start Enhancement
The multi-round iterative paradigm collaboratively enhances both cold-start and RL models:

  1. Apply cold-start model as initial model for General RL training
  2. Use RL model for rejection sampling on Cold Start dataset, replacing ground truth with better sampled results
  3. Train new cold-start model with updated data for next-round General RL
  4. Filter General RL dataset using updated cold-start model, selecting data with sampling accuracy between 0-1

Alignment RL: Comprehensive Performance Improvement
Alignment RL enhances real-world application performance across dimensions:


  • Instruction Following: Meeting user requirements for content, format, length, and structured output

  • Format Adherence: Conforming to predefined formats (think-answer, agentic think, auto-think, no-think)

  • Preference Alignment: Enhancing reliability, interactivity, and response style for open-ended questions

The reward system combines:


  • Rule-Based Reward: Checking structural and formatting rules adherence

  • Generative Reward: Evaluating alignment with reference, reasoning consistency, and key attributes relatedness

  • Model-Based Reward: Scoring responses without ground truth based on human preference alignment

Data construction includes:


  • Instruction-following tasks with 25 hard constraints and 20 soft constraints across 17k multimodal and 23k pure text queries

  • Reasoning tasks with 12k mathematical and logical reasoning queries requiring 3-5 prescribed steps

  • RAG tasks based on latest news requiring internet searches, encouraging search and summary behaviors

Training Infrastructure: Supporting Advanced Model Development

What infrastructure optimizations enable efficient MLLM training? Keye-VL 1.5 addresses three major challenges through in-depth infrastructure optimization.

Heterogeneous Hybrid Parallel Strategy
The training bottleneck stems from computational imbalance caused by architectural heterogeneity between ViT and LLM components. The solution implements:


  • Data parallelism only for ViT’s relatively fixed computational pattern

  • Hybrid parallelism (pipeline, tensor, and data) for parameter- and memory-intensive LLM

  • This refined strategy enables 128K ultra-long sequence training

Dynamic Load Balancing Mechanism
Multimodal data inherently causes load imbalance due to computational load variations in visual encoding. The solution:


  • Pre-estimates time complexity of each sample

  • Uses greedy algorithm to allocate samples across GPUs

  • Balances total step duration across all GPUs

  • Improves overall hardware utilization

Flexible and Scalable Dataloader
The solution fundamentally resolves I/O bottlenecks through:


  • Topology-aware data loading: each process loads only a shard of the global dataset

  • Pipeline parallelism: only first stage (PP0) handles data acquisition and preprocessing

  • Tensor parallelism: single process fetches data and broadcasts within group

  • I/O server architecture offloading CPU-intensive tasks (video decoding) from training nodes

  • Instance-level perfect resume mechanism ensuring seamless recovery after interruptions

Performance Evaluation: Demonstrating Superior Capabilities

How does Keye-VL 1.5 perform across various benchmarks? Comprehensive evaluation demonstrates significant improvements over previous versions and competitive performance against industry benchmarks.

Zero-shot Image Classification
The continued trained native-resolution ViT shows promising visual representations across six benchmark datasets:


  • ImageNet-1K: 82.65% (with 1D interpolation + 2D RoPE)

  • ImageNet-V2: 76.80%

  • ImageNet-A: 83.26%

  • ImageNet-R: 95.22%

  • ImageNet-S: 72.59%

  • ObjectNet: 78.70%

The 2D RoPE modification enables clear perception of image shape, showing competitive results with base SigLIP performance.

Slow-Fast Video Encoding Validation
Comparison with Qwen-2.5-VL’s 2D convolution technique on VideoMME benchmark demonstrates:


  • Similar overall performance trend but later inflection points for sub-categories

  • More flexible token usage: more visual tokens at low frame numbers, fewer at high frame numbers

  • Greater stability across different FPS settings

  • Efficient computational resource utilization

Public Benchmarks Performance
Keye-VL-1.5 demonstrates competitive performance across general vision-language tasks, often achieving SOTA or near-SOTA results:


  • OpenCompass: 79.5%

  • MMMU_val: 71.4%

  • AI2D: 89.5%

  • MMBench: 92.0%

  • Video-MME: 73.0%

  • Video-MMMU: 66.0% (6.5% absolute improvement)

  • Strong mathematical reasoning performance surpassing Qwen2.5-VL 8B and InternVL3-8B

Internal Benchmarks Evaluation
The proprietary internal evaluation suite addresses limitations of public benchmarks:


  • Comprehensive coverage including Visual Element Recognition, Reasoning Ability, Temporal Info Understanding, Knowledge-based QA, Description Ability, Robustness, Creative Ability, and Domain Expertise

  • Rigorous scoring methodology using comparative evaluation and GSB preference selection

  • Avoidance of data contamination and language/cultural bias

Keye-VL-1.5-8B achieves an overall composite score of 3.53, representing a +0.51 improvement over Keye-VL-Preview. The model demonstrates particular strength in Reasoning Ability (3.81), Temporal Information Understanding (3.36), and Robustness (4.29), with the latter showing a substantial +0.83 lead over MiMoVL-7B-RL-2508.

Practical Implementation: Getting Started with Keye-VL 1.5

How can developers and researchers implement Keye-VL 1.5 in their projects? The model offers multiple deployment options suitable for different use cases.

Installation and Basic Usage

pip install keye-vl-utils

Basic Inference Example

from transformers import AutoModel, AutoProcessor
from keye_vl_utils import process_vision_info

# Load model and processor
model = AutoModel.from_pretrained(
    "Kwai-Keye/Keye-VL-1.5-8B",
    torch_dtype="auto",
    device_map="auto",
    trust_remote_code=True
)

processor = AutoProcessor.from_pretrained(
    "Kwai-Keye/Keye-VL-1.5-8B", 
    trust_remote_code=True
)

# Prepare messages with mixed content
messages = [
    {
        "role": "user",
        "content": [
            {"type": "image", "image": "https://example.com/image.jpg"},
            {"type": "text", "text": "Describe this image in detail."}
        ]
    }
]

# Process inputs
text = processor.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
image_inputs, video_inputs, mm_kwargs = process_vision_info(messages)

inputs = processor(
    text=[text],
    images=image_inputs,
    videos=video_inputs,
    padding=True,
    return_tensors="pt",
    **mm_kwargs
).to("cuda")

# Generate response
generated_ids = model.generate(**inputs, max_new_tokens=1024)
output_text = processor.batch_decode(
    generated_ids[:, inputs.input_ids.shape[1]:], 
    skip_special_tokens=True
)
print(output_text[0])

vLLM Deployment for Production

For high-throughput scenarios, vLLM deployment provides optimal performance:

pip install keye-vl-utils "vllm>=0.9.2"

Server Deployment

vllm serve Kwai-Keye/Keye-VL-1.5-8B \
    --tensor-parallel-size 8 \
    --enable-prefix-caching \
    --gpu-memory-utilization 0.8 \
    --host 0.0.0.0 \
    --port 8000 \
    --trust-remote-code

API Client Example

from openai import OpenAI

client = OpenAI(
    api_key="EMPTY",
    base_url="http://localhost:8000/v1"
)

response = client.chat.completions.create(
    model="Kwai-Keye/Keye-VL-1.5-8B",
    messages=[{
        "role": "user",
        "content": [
            {"type": "image_url", "image_url": {
                "url": "https://example.com/image.jpg"
            }},
            {"type": "text", "text": "What's in this image?"}
        ]
    }]
)
print(response.choices[0].message.content)

Real-World Applications and Use Cases

What practical problems can Keye-VL 1.5 solve? The model’s capabilities enable diverse applications across industries.

Video Content Analysis
The model excels at temporal understanding and event detection in videos. In a 26-second product review video, it accurately identified a handbag’s appearance window from 22.3 to 23.8 seconds with 0.1-second precision, demonstrating fine-grained temporal localization capabilities.

Behavior Understanding and Interpretation
In complex scenarios involving multiple actors, the model provides nuanced interpretations. When analyzing dog behavior video, it correctly identified that a larger dog biting a smaller dog’s ear served as corrective behavior rather than aggression, showing advanced contextual understanding.

Detailed Scene Description
For visually complex scenes, the model generates comprehensive descriptions capturing both obvious and subtle elements. When processing forest footage with hail precipitation, it accurately described environmental conditions, vegetation, lighting, and atmospheric effects despite some challenge identifying the specific precipitation type.

Document Processing and OCR
The model handles diverse document types including structured documents, handwritten text, and complex layouts. It supports specific instruction following for tasks like extracting text from particular columns or regions, making it valuable for automated document processing workflows.

Multimodal Reasoning
Combining visual information with textual knowledge, the model solves complex problems requiring integrated understanding. This capability proves valuable for educational applications, technical documentation analysis, and scientific problem-solving.

Action Checklist: Implementing Keye-VL 1.5

For teams looking to implement Keye-VL 1.5 in their projects, follow these essential steps:

  1. Environment Setup


    • Install keye-vl-utils package

    • Ensure compatible hardware (GPU with sufficient VRAM)

    • Set up Python environment with required dependencies
  2. Model Selection


    • Choose between Keye-VL-1.5-8B for balanced performance

    • Consider quantization options for resource-constrained environments

    • Evaluate need for specialized capabilities (video, OCR, etc.)
  3. Integration Approach


    • Decide between direct Transformer implementation or vLLM serving

    • Plan for batch processing requirements

    • Implement appropriate error handling and fallback mechanisms
  4. Performance Optimization


    • Configure appropriate token limits for your use case

    • Implement caching strategies for frequent queries

    • Set up monitoring for latency and resource usage
  5. Evaluation Framework


    • Establish baseline metrics for your specific tasks

    • Create test suites covering edge cases and failure modes

    • Implement continuous evaluation against real-world data

One-Page Summary: Keye-VL 1.5 Essentials

Core Innovations


  • Slow-Fast video encoding: Dynamic resource allocation based on content characteristics

  • Progressive pre-training: Four-stage approach building from 8K to 128K context length

  • Comprehensive post-training: Enhanced reasoning and human preference alignment

Performance Highlights


  • State-of-the-art results on video understanding benchmarks

  • Strong performance across general multimodal tasks

  • Excellent mathematical and logical reasoning capabilities

  • Robust Chinese and English language support

Technical Specifications


  • 8B parameter model

  • 128K token context length

  • Native dynamic resolution support

  • Mixed precision training and inference

Deployment Options


  • Direct Hugging Face Transformers integration

  • vLLM serving for high-throughput scenarios

  • OpenAI-compatible API interface

  • Custom integration support

Ideal Use Cases


  • Video content analysis and summarization

  • Complex multimodal reasoning tasks

  • Document processing and OCR

  • Educational and training applications

  • Research and development in multimodal AI

Frequently Asked Questions

What makes Keye-VL 1.5 different from other multimodal models?
Keye-VL 1.5 introduces three key innovations: a novel Slow-Fast video encoding strategy that dynamically allocates computational resources based on content characteristics, progressive pre-training that systematically extends context length to 128K tokens, and comprehensive post-training focusing on reasoning enhancement and human preference alignment.

What types of video content does Keye-VL 1.5 handle best?
The model excels at videos with varying motion dynamics, as its Slow-Fast encoding strategy automatically adapts to content characteristics. It performs particularly well on content requiring temporal understanding, such as sports analytics, surveillance footage, and instructional videos.

How does the model handle different languages, particularly Chinese?
Keye-VL 1.5 demonstrates strong capabilities in both English and Chinese, with specialized enhancements for Chinese OCR through font rendering synthesis and instruction-following OCR datasets designed specifically for Chinese language characteristics.

What computational resources are required for deployment?
The 8B parameter model can run on modern GPUs with sufficient VRAM. For optimal performance, especially with long contexts or batch processing, higher-end GPUs or multi-GPU setups are recommended. vLLM deployment helps optimize resource utilization for production scenarios.

Can the model process real-time video streams?
While primarily designed for pre-recorded content, the model’s efficient encoding strategy and performance characteristics make it suitable for near-real-time applications with appropriate optimization and hardware resources.

How does the model handle ambiguous or challenging visual content?
Through its comprehensive training pipeline including progressive hint sampling and reinforcement learning with verifiable rewards, the model develops robust handling of challenging content. It can recognize when information is ambiguous and provide appropriate qualified responses.

What types of reasoning tasks is the model particularly good at?
The model excels at mathematical reasoning, logical inference, temporal understanding, and complex multimodal reasoning that requires integrating information from visual and textual sources simultaneously.

How can developers fine-tune the model for specific applications?
The model supports standard fine-tuning approaches, with particular strength in leveraging its comprehensive post-training methodology for domain-specific adaptation while maintaining general capabilities.