PlantUML Manipulator Skill

When to Use This Skill

Use this skill for:

• Repetitive changes to multiple PlantUML files (e.g., insert block into 10+ files)
• Structural validation of diagrams (checking for missing groups/participants)
• Batch operations like adding participants to multiple files
• Reporting on existing structures (which groups/participants exist where)

Do not use for:

• Single, one-time changes to 1-2 files (use normal Edit tools)
• Complex semantic changes requiring contextual understanding
• Non-sequence PlantUML diagrams

Tool Availability

The tool is located at: ./tool/plantuml-manipulator/

First check if the tool is implemented:

python -m plantuml_manipulator --help

If not available, inform the user that implementation is pending.

Main Commands

1. Insert Block After Group

Most common scenario: Insert a code block after a specific group in multiple files.

Workflow:

1. Create a snippet file with the block to insert
2. Run with --dry-run to preview changes
3. If OK, run without --dry-run

Example:

# 1. Create snippet (you do this with Write tool)
# snippets/validation.puml contains the block to insert

# 2. Dry-run
python -m plantuml_manipulator insert-after \
  --pattern "diagrams/**/*.puml" \
  --after-group "Process Request" \
  --block-file snippets/validation.puml \
  --dry-run \
  --verbose

# 3. Execute if OK
python -m plantuml_manipulator insert-after \
  --pattern "diagrams/**/*.puml" \
  --after-group "Process Request" \
  --block-file snippets/validation.puml \
  --verbose

Important flags:

• --skip-if-exists "TEXT": Skip files already containing "TEXT"
• --only-if-has-participant "NAME": Only files with participant NAME
• --backup: Create .bak files before changes

2. Add Participant

Adds a participant to multiple files at the correct position.

Example:

python -m plantuml_manipulator add-participant \
  --pattern "diagrams/**/*.puml" \
  --participant 'participant "API" as API #orange' \
  --after-participant "Frontend" \
  --skip-if-exists "API" \
  --verbose

3. Validation

Checks if all files contain required structures.

Example:

python -m plantuml_manipulator validate \
  --pattern "diagrams/**/*.puml" \
  --require-group "Perform Validation" \
  --require-participant "API" \
  --report-format table

4. Reporting

Creates overviews of existing structures.

Examples:

# List all groups
python -m plantuml_manipulator report groups \
  --pattern "diagrams/**/*.puml" \
  --format table

# List all participants
python -m plantuml_manipulator report participants \
  --pattern "diagrams/**/*.puml" \
  --format json

# Show structure of a single file
python -m plantuml_manipulator report structure \
  --file "diagrams/user_login.puml"

Best Practices

1. Always Dry-Run First

IMPORTANT: Always run with --dry-run first to see what would happen.

# ✓ Correct
python -m plantuml_manipulator insert-after ... --dry-run
# Review output
python -m plantuml_manipulator insert-after ...

# ✗ Wrong
python -m plantuml_manipulator insert-after ...  # Without prior dry-run

2. Use --skip-if-exists

Prevent duplicate insertions:

python -m plantuml_manipulator insert-after \
  --after-group "Process Request" \
  --block-file snippets/validation.puml \
  --skip-if-exists "Perform Validation"  # ✓ Prevents duplicates

3. Use Filters for Targeted Operations

Instead of modifying all files, filter specifically:

# Only files with specific participant
--only-if-has-participant "PaymentService"

# Only files with specific group
--only-if-has-group "Process Data"

4. Backup for Large Changes

Always create backups when modifying many files:

python -m plantuml_manipulator insert-after \
  ... \
  --backup  # Creates .bak files

5. Validate After Changes

Check if changes were successful:

# After block insertion
python -m plantuml_manipulator validate \
  --pattern "..." \
  --require-group "New Group Name"

Integration with Normal Tools

This tool is a supplement, not a replacement for normal Edit/Read tools:

Use PlantUML Manipulator:

• For 5+ similar changes
• When exact structural patterns exist
• For validation/reporting

Use Normal Edit Tools:

• For individual, context-dependent changes
• For complex logic changes
• For 1-3 files

Communicating with the User

When using this skill, inform the user:

Before execution:

I'm now using the PlantUML Manipulator tool to insert the validation
into 8 files.

First, I'll run a dry-run to check what would happen...

After dry-run:

The dry-run shows that 8 files would be modified:
- user_login.puml
- payment_process.puml
- ...

Shall I proceed?

After successful execution:

✓ Successfully completed:
  - 8 files modified
  - API participant added to 7 files
  - Validation group inserted into 8 files
  - Backup files created (.bak)

Further Information

For detailed API reference see: ../../api-reference.md For full specification see: ../../specification.md