LikeC4 CLI Codegen Regression

Protect likec4 gen output contracts with focused tests. The most important invariant is that multi-file generators write every emitted view under the requested output directory.

Ground rules

• Start in packages/likec4/src/cli/codegen.
• Add a regression test before implementation when fixing a bug.
• Test every affected multi-file format, not only the format that exposed the issue.
• Treat external include-path views and Windows paths as first-class edge cases.

Output-path invariants

For likec4 gen dot, d2, mermaid or mmd, and plantuml:

• --outdir or -o defines the containment root for all generated files.
• Source-relative view paths must never escape the output root.
• Absolute source paths, parent-relative paths, and Windows drive-root paths must not create files outside --outdir.
• A view coming from an external include path should still be emitted under --outdir.
• Define and assert the resulting output naming contract for escaped or external source paths; containment-only checks are not enough.
• Single-file generators such as model, react, or webcomponent should keep their existing --outfile behavior.

Regression matrix

Cover the smallest matrix that proves the contract:

Formats to consider:

• .dot
• .d2
• .mmd
• .puml

Test shape

Use a temp workspace fixture:

workspace/
  project-a/
    likec4.config.ts
    project-view.c4
  shared/
    included-view.c4
  out/

Configure project-a to include ../shared. Run each generator with --outdir workspace/out.

Assert:

• expected files exist inside workspace/out
• escaped or external source paths use the explicitly chosen output naming contract
• no generated file exists under project-a, shared, or the temp workspace root outside out
• all generated paths pass an isInside(outdir, filepath) style check

If the real fixture cannot produce absolute or Windows drive-style sourcePath values, extract a small path-resolution helper and cover those cases with pure unit tests.

Focused commands

pnpm --filter likec4 test -- codegen
pnpm --filter likec4 typecheck
pnpm exec dprint check packages/likec4/src/cli/codegen
git diff --check

If touching shared path utilities, also run the package tests that own those utilities.