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Fingerprint and lineage

Each Acton project must declare a fingerprint in Build.act. The fingerprint represents the project’s lineage — a stable identity that stays the same across releases of the same project.

name = "myproject"
fingerprint = 0x1234abcd5678ef00

What the fingerprint is

  • A 64-bit hex value (0x...).
  • The upper 32 bits are derived from the project name.
  • The lower 32 bits are random.
  • Acton uses this lineage to deduplicate dependencies and to generate consistent build metadata.

Rename vs fork

Renaming a project breaks lineage, so generate a new fingerprint for the new name. Forking a project also creates a new lineage, so generate a fresh fingerprint.

If Acton detects a mismatch, it will fail the build and tell you to generate a new fingerprint for the name.

Current behavior

  • name and fingerprint are required in every project.
  • Acton validates the lineage prefix derived from the name.
  • Missing or mismatched values fail the build with guidance.