Add path to created attestation in a well-known summary file

[kommendorkapten]

For a situation where multiple attestations are created in a workflow, write the path to each file in a well-known file. This allows for creation of summary steps that can easily read this and act on the created attestations, without knowing about all the steps and their id:s.

The file chosen to be the well-known file is ${RUNNER_TEMP}/created_attestation_paths.txt. Each attestation is appended to that file, one path to an attestation per line.

[Copilot]

Pull Request Overview

Adds tracking of all created attestations by appending their paths to a summary file and documents this behavior in the README.

• Introduce created_attestation_paths.txt constant and append each attestation path to this file in main.ts
• Update README to explain how to locate all attestation files via ${RUNNER_TEMP}/created_attestation_paths.txt

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/main.ts	Append each generated attestation file path to a summary file in runner temp
README.md	Document the new summary file and its usage

Comments suppressed due to low confidence (1)

src/main.ts:86

• [nitpick] Consider adding a unit test that verifies this summary file is created and that appendFileSync is called with the correct path and data.

fs.appendFileSync(outputSummaryPath, outputPath + os.EOL, {