Trestle Authoring Workflow

The Generate-Edit-Assemble Cycle

Trestle's authoring tools convert OSCAL JSON to markdown for human editing, then back to JSON:

JSON (OSCAL) → generate → Markdown (edit) → assemble → JSON (OSCAL)

This cycle is continuous: after initial generation, you repeatedly edit markdown and reassemble.

Author Commands by Model Type

Catalog Authoring

• trestle author catalog-generate --name <catalog> --output <md_dir> → markdown per control
• trestle author catalog-assemble --markdown <md_dir> --output <catalog> → JSON catalog

Profile Authoring

• trestle author profile-generate --name <profile> --output <md_dir> → markdown with profile additions
• trestle author profile-assemble --markdown <md_dir> --output <profile> → JSON profile
• trestle author profile-resolve --name <profile> --output <resolved> → resolved profile catalog

Component Definition Authoring

• trestle author component-generate --name <compdef> --output <md_dir> → markdown per component/control
• trestle author component-assemble --markdown <md_dir> --output <compdef> → JSON component-definition

SSP Authoring

• trestle author ssp-generate --profile <profile> --compdefs <comp1,comp2> --output <md_dir> → markdown per control
• trestle author ssp-assemble --markdown <md_dir> --output <ssp> → JSON SSP
• trestle author ssp-filter --name <ssp> --profile <profile> --output <filtered> → filtered SSP

Markdown Structure

Control Markdown File

Each control gets its own .md file with:

1. YAML header - metadata, parameters, properties
2. Control title - # control-id - [Group Title] Control Title
3. Control Statement - ## Control Statement with labeled parts
4. Control guidance - ## Control guidance
5. Additional sections - Implementation responses, component sections

YAML Header Tags (x-trestle-*)

Tag	Purpose
x-trestle-set-params	Parameter values for the control
x-trestle-global	Global metadata (sort-id, profile title)
x-trestle-sections	Map of section short names to display names
x-trestle-add-props	Properties to add to the control
x-trestle-comp-def-rules	Rules from component definitions
x-trestle-comp-def-rules-param-vals	Rule parameter values
x-trestle-inherited-props	Properties inherited from upstream
x-trestle-leveraging-comp	Leveraged component information
x-trestle-statement	Statement-level metadata

Parameter Handling

In catalog markdown (x-trestle-set-params):

x-trestle-set-params:
  ac-1_prm_1:
    values:
      - organization-defined value
    label: descriptive label

In profile markdown (adds profile-values):

x-trestle-set-params:
  ac-1_prm_1:
    values:
      - catalog value
    profile-values:
      - profile-specific value

In SSP markdown (adds ssp-values):

x-trestle-set-params:
  ac-1_prm_1:
    values:
      - resolved value
    ssp-values:
      - ssp-specific value

Key Options

Option	Commands	Purpose
--set-parameters	catalog-assemble, profile-assemble	Apply parameter changes from YAML header
--overwrite-header-values	all -generate	Overwrite existing header values with provided YAML
--force-overwrite	all -generate	Erase existing markdown before regenerating
--yaml / -y	all -generate	Provide external YAML header to merge
--version	all -assemble	Set version in assembled model
--regenerate	all -assemble	Generate new UUIDs
--sections	profile-assemble	Define allowed sections
--required-sections	profile-assemble	Sections that must be present
--compdefs	ssp-generate	Comma-separated component definitions

Implementation Status Values

Controls track implementation status with these values:

• implemented - Fully implemented
• partial - Partially implemented
• planned - Implementation is planned
• alternative - Alternative implementation
• not-applicable - Control is not applicable

Control Origination Values

• organization - Organization-level
• system-specific - System-specific
• customer-configured - Customer configured
• customer-provided - Customer provided
• inherited - Inherited from another system

CI/CD Integration

The authoring tools are designed for CI/CD pipelines:

• Assemble commands only write output if content changed (prevents unnecessary triggers)
• --set-parameters limits what can change during automated assembly
• --required-sections and --allowed-sections enforce document structure
• Individual control markdown files enable fine-grained git tracking

Multi-Repository Coordination

Large organizations split OSCAL artifacts across multiple Git repositories aligned to ownership boundaries. Trestle's authoring tools support this through CI/CD-driven propagation.

Repository Topology

catalog-repo (Regulators)
    |
    v  imports
profile-repo (Compliance Officers)
    |
    v  references
compdef-repo (Vendors / Control Providers)
    |
    v  combined into
ssp-repo (System Owners)

Each repository contains its own trestle workspace (.trestle/ directory) and manages artifacts independently with its own CI/CD pipeline.

Change Propagation Pattern

When an upstream artifact changes:

1. Upstream repo merges markdown edits to main
2. CI/CD runs trestle author *-assemble to rebuild OSCAL JSON
3. If JSON changed, CI/CD creates a PR in each downstream repository
4. Downstream owners review the PR, which pulls the updated upstream artifact
5. On merge, the downstream CI/CD assembles its own artifacts with the new input

This pattern uses repository_dispatch events (GitHub Actions) or cross-project triggers (GitLab CI) to connect repositories.

When to Use Multi-Repo vs Single-Repo

Factor	Single Repo	Multi-Repo
Team size	Small (1-5 people)	Multiple teams or organizations
Ownership	Same team owns all artifacts	Different teams own different artifacts
Release cadence	Artifacts change together	Independent versioning needed
Access control	Same permissions for all	Different access per artifact type
Complexity	Simpler setup and maintenance	Better separation of concerns

Start with a single repo. Split when ownership boundaries emerge or when independent versioning is required.

Two-Phase Component Definition Authoring

Component definitions combine structured rule data with narrative prose. Trestle supports a two-phase authoring pattern that uses the best tool for each type of content.

Phase 1: Rules via CSV Spreadsheet

# CSV contains structured mappings: rules, parameters, control associations
trestle task csv-to-oscal-cd

The CSV captures:

• Rule_Id, Rule_Description — the technical rule
• Control_Id_List — which regulation controls this rule implements
• Parameter_Id, Parameter_Value_Alternatives — configurable parameters
• Component_Type — Service (control-to-rule) or Validation (rule-to-check)

Vendors manage this CSV in spreadsheet tools. It is committed to Git and converted to OSCAL JSON via the csv-to-oscal-cd task.

Phase 2: Responses via Markdown

# Generate markdown from the Phase 1 component definition
trestle author component-generate --name my-service --output md_compdefs/my-service

# Markdown shows rules (read-only) + editable prose sections
# Edit: write implementation descriptions per control per component
# Then reassemble
trestle author component-assemble --markdown md_compdefs/my-service --output my-service

The markdown includes:

• Read-only rules section (from Phase 1 CSV data)
• Read-only control description and guidance (from catalog/profile)
• Editable implementation response sections (prose describing HOW the control is met)
• Implementation status (implemented, partial, planned, etc.)

Why Two Phases?

• Structured data (rules, parameters, mappings) is best managed in spreadsheets
• Narrative prose (implementation descriptions) is best edited as markdown
• Different personas may own each phase (security engineers write rules; product owners write prose)
• Phase 1 can be automated from tooling; Phase 2 requires human judgment

Git-Based Authoring Workflow

Trestle's authoring tools are designed for Git-based collaboration with CI/CD automation.

PR-Based Review Cycle

1. Author edits markdown on a feature branch
2. Opens a PR for peer review
3. CI/CD runs trestle validate on the PR to catch errors early
4. Reviewers approve; PR is merged to main
5. CI/CD on main runs trestle author *-assemble to rebuild OSCAL JSON
6. If JSON changed, CI/CD commits the updated JSON and (optionally) triggers downstream repos

Conditional Write Behavior

Assemble commands only write output if content changed. This prevents:

• Unnecessary git commits (no-op changes to JSON)
• Infinite CI/CD trigger loops between repositories
• Misleading git history with empty diffs

Branch Protection Recommendations

Branch	Protection	Who Can Merge
main	Require PR review + CI/CD pass	Artifact owner (per persona)
Feature branches	No protection	Any contributor

Individual control markdown files enable fine-grained git tracking — reviewers can see exactly which controls were modified in a PR diff.

Models Without Author Commands

Not all OSCAL models have trestle author generate/assemble commands. The following models use a JSON-based workflow instead:

Model	trestle author Support	Workflow
Catalog	catalog-generate / catalog-assemble	Markdown roundtrip
Profile	profile-generate / profile-assemble	Markdown roundtrip
Component Definition	component-generate / component-assemble	Markdown roundtrip
SSP	ssp-generate / ssp-assemble	Markdown roundtrip
Assessment Plan	None	create → split → edit → merge → validate
Assessment Results	None	create → split → edit → merge → validate
POA&M	None	create → split → edit → merge → validate

JSON-Based Workflow

For assessment plans, assessment results, and POA&M:

# 1. Create a new model with placeholder fields
trestle create -t <model-type> -o <name>

# 2. Split into editable sections
trestle split -f <model-file>.json -e '<model-type>.<element1>,<model-type>.<element2>'

# 3. Edit the resulting JSON files directly

# 4. Merge sections back together
trestle merge -e '<model-type>.<element1>,<model-type>.<element2>'

# 5. Validate the final model
trestle validate -t <model-type> -n <name>

For detailed workflows, see the trestle-assessment skill (assessment plans and results) and the trestle-poam skill (plan of action and milestones).