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models-trainingNote A.06Revision 2026.09

Custom Model Development

A custom model is an owned lifecycle spanning data, adaptation, evaluation, serving, and rollback.

Design the build-versus-adapt decision, organization-specific layers, versioning, safety gates, and deployment boundaries.

01

Problem definition

When the goal of owning a model precedes the work problem, the result is an expensive asset to maintain.

When a training checkpoint differs from its served form, evaluation no longer represents operating quality.

  • Data, latency, cost, or sovereignty requirements cannot be met by general APIs
  • The organization is prepared to own model assets and operations long term
  • The problem can be solved at retrieval, workflow, or authority layers
  • Evaluation and update owners are undefined
02

Custom Model Development: system plate

Client boundaryData, latency, cost, or sovereignty requirements cannot be met by general APIs
  • When the goal of owning a model precedes the work problem, the result is an expensive asset to maintain.
  • Not every problem is solved with a proprietary model.
PattyCompare general APIs, RAG, SFT, CPT, and new builds against one acceptance frame.
  • Separate ownership of reusable foundations from organization-specific data, adapters, and policy.
  • Workload acceptance criteria
AcceptanceServed-form regression
  • Update and rollback reproducibility
  • Cost, schedule, and improvement magnitude are not guaranteed in advance.
A decision and validation view for Custom Model Development; labels describe architecture, not a measured deployment result.
  1. The workflow begins with Compare general APIs, RAG, SFT, CPT, and new builds against one acceptance frame..
  2. It reaches an acceptance decision through Workload acceptance criteria.

03

Design method

A custom model is an owned lifecycle spanning data, adaptation, evaluation, serving, and rollback.

  1. 01

    Stage 1

    Compare general APIs, RAG, SFT, CPT, and new builds against one acceptance frame.

  2. 02

    Stage 2

    Separate ownership of reusable foundations from organization-specific data, adapters, and policy.

  3. 03

    Stage 3

    Link training, merge, quantization, and serving versions in one model release manifest.

  4. 04

    Stage 4

    Make safety, quality, performance gates, and a rollback version operating acceptance conditions.

04

Application scenarios

Hypothetical application scenario

Data, latency, cost, or sovereignty requirements cannot be met by general APIs

When the goal of owning a model precedes the work problem, the result is an expensive asset to maintain.

APPROACH
Compare general APIs, RAG, SFT, CPT, and new builds against one acceptance frame.
BOUNDARY
Not every problem is solved with a proprietary model.
Hypothetical application scenario

The organization is prepared to own model assets and operations long term

When a training checkpoint differs from its served form, evaluation no longer represents operating quality.

APPROACH
Separate ownership of reusable foundations from organization-specific data, adapters, and policy.
BOUNDARY
Cost, schedule, and improvement magnitude are not guaranteed in advance.

05

Design choices

DecisionGainCostWatch
Data, latency, cost, or sovereignty requirements cannot be met by general APIsCompare general APIs, RAG, SFT, CPT, and new builds against one acceptance frame.Not every problem is solved with a proprietary model.Workload acceptance criteria
The organization is prepared to own model assets and operations long termSeparate ownership of reusable foundations from organization-specific data, adapters, and policy.Cost, schedule, and improvement magnitude are not guaranteed in advance.Served-form regression
06

Custom Model Development: system plate

CONTROL

System 1

Compare general APIs, RAG, SFT, CPT, and new builds against one acceptance frame.

CONTROL

System 2

Separate ownership of reusable foundations from organization-specific data, adapters, and policy.

EXECUTION

System 3

Link training, merge, quantization, and serving versions in one model release manifest.

EXECUTION

System 4

Make safety, quality, performance gates, and a rollback version operating acceptance conditions.

  1. N1 N2context
  2. N2 N3decision
  3. N3 N4evidence
A decision and validation view for Custom Model Development; labels describe architecture, not a measured deployment result.
  1. The workflow begins with Compare general APIs, RAG, SFT, CPT, and new builds against one acceptance frame..
  2. It reaches an acceptance decision through Workload acceptance criteria.

07

Validation plan

MeasureMethodPass conditionCaveat
Workload acceptance criteriaCompare general APIs, RAG, SFT, CPT, and new builds against one acceptance frame.Repeated runs satisfy the acceptance threshold agreed during discoveryNot every problem is solved with a proprietary model.
Served-form regressionSeparate ownership of reusable foundations from organization-specific data, adapters, and policy.Repeated runs satisfy the acceptance threshold agreed during discovery—
Update and rollback reproducibilityLink training, merge, quantization, and serving versions in one model release manifest.Repeated runs satisfy the acceptance threshold agreed during discovery—

08

Constraints and failure conditions

The problem can be solved at retrieval, workflow, or authority layers

Not every problem is solved with a proprietary model.

Evaluation and update owners are undefined

Cost, schedule, and improvement magnitude are not guaranteed in advance.

10

Durable deliverables

Custom Model Development decision record
A custom model is an owned lifecycle spanning data, adaptation, evaluation, serving, and rollback.Client-owned · Patty-reviewed
Validation harness and acceptance criteria
Workload acceptance criteria · Served-form regression · Update and rollback reproducibilityJointly maintained
Operations and recovery runbook
Not every problem is solved with a proprietary model. · Cost, schedule, and improvement magnitude are not guaranteed in advance.Operating-team owned

11

Terminology

Custom Model Development
Design the build-versus-adapt decision, organization-specific layers, versioning, safety gates, and deployment boundaries.
Acceptance criterion
Workload acceptance criteria
Operating boundary
Not every problem is solved with a proprietary model.

REFERENCES

References and primary material

  1. PEFT

    Primary material for the method and terminology.

  2. AutoRound

    Primary material for the method and terminology.

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