PlantUML linker fails on generated .fbs.bin with UTF-8 error although source .puml is ASCII-only

[simon-d-bmw]

Summary

A sequence diagram parses successfully with the PlantUML parser step, but the later linker step fails while reading the generated .fbs.bin with a UTF-8 error in the source_file field.

Observed behavior

Warning / failure shape:

Failed to parse FlatBuffer ... Utf8 error ... while verifying table field 'source_file'

Affected source:
attribute_access_getter_sequence.puml

Generated artifact:
attribute_access_getter_sequence.fbs.bin

Expected behavior

If the source .puml parses successfully, the generated FlatBuffer should also be consumable by the linker.

Why this looks like a tooling bug

• The .puml source is ASCII-only.
• puml_cli parses it successfully.
• The failure appears only in the linker while verifying the generated FlatBuffer.

Impact

Valid diagrams can still trigger downstream linker warnings/failures, making architectural-design validation noisy and less trustworthy.

Narrow repro

Build the architectural / dependable-element docs containing the affected sequence diagram.

Notes

This may be adjacent to the ongoing PlantUML idmap/linker refactor work (#290, #321, #322, #323), but those PRs do not appear to describe this UTF-8 / FlatBuffer failure explicitly.

Suspected area

Mismatch between:

• PlantUML parser output
• FlatBuffer schema/content
• linker-side verification expectations