fix : improved sequence diagram new actors rendering and autonumber positioning for all types of arrows and central connections

[omkarht]

📑 Summary

This PR fixes critical autonumber positioning issues for sequence diagrams across all arrow types, adds missing helper functions, and improves actor rendering consistency.

Key Changes:

1. Fixed Autonumber Positioning (sequenceRenderer.ts)

• Bidirectional arrows: Adjusted line start position with proper radius offset and central connection spacing
• Reverse arrows: Corrected line stop position at arrowhead with special handling for central connections
• Normal arrows: Maintained consistent positioning with radius offset
• Self-reference arrows: Fixed line start offset for reverse and bidirectional types when autonumber is enabled
• Autonumber placement: Calculated correct X position based on message direction, arrow type, and actor bounds

2. Enhanced Central Connection Rendering (sequenceRenderer.ts)

• Implemented dynamic circle positioning when autonumber is enabled
• Added getCircleOffset() helper function with directional logic (LTR/RTL)
• Proper offset calculations for:
  • CENTRAL_CONNECTION - circle at destination
  • CENTRAL_CONNECTION_REVERSE - circle at source
  • CENTRAL_CONNECTION_DUAL - circles at both ends
• Handles reverse arrows with inverted offsets

3. Improved Actor Rendering (svgDraw.js)

• Control actor: Increased radius (18→22), adjusted vertical positioning
• Entity actor: Increased radius (18→22), removed hardcoded stroke color, improved text positioning
• Database actor: Optimized cylinder dimensions (w/4→w/3), centered positioning, consistent text placement
• Boundary actor: Adjusted radius (30→22), improved stick figure positioning and alignment

Resolves #

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commit: de54798

[codecov]

Codecov Report

❌ Patch coverage is 0% with 133 lines in your changes missing coverage. Please review.
✅ Project coverage is 3.54%. Comparing base (2346801) to head (de54798).

Files with missing lines	Patch %	Lines
.../mermaid/src/diagrams/sequence/sequenceRenderer.ts	0.00%	112 Missing ⚠️
packages/mermaid/src/diagrams/sequence/svgDraw.js	0.00%	21 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           develop   #7150      +/-   ##
==========================================
- Coverage     3.55%   3.54%   -0.01%     
==========================================
  Files          473     474       +1     
  Lines        47500   47599      +99     
  Branches       731     731              
==========================================
  Hits          1687    1687              
- Misses       45813   45912      +99     

Flag	Coverage Δ
unit	3.54% <0.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
packages/mermaid/src/diagrams/sequence/svgDraw.js	0.00% <0.00%> (ø)
.../mermaid/src/diagrams/sequence/sequenceRenderer.ts	0.06% <0.00%> (-0.01%)	⬇️

... and 1 file with indirect coverage changes

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Build	Status	Details	Updated (UTC)
default (Inspect)	👍 Changes approved	46 changed, 28 added	Nov 25, 2025, 10:48 AM