Fix YAML indentation bug in AI prompt template substitution - #592
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dblock merged 1 commit intoAug 12, 2026
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actions/ai-inference@v1 substitutes {{var}} placeholders as raw text
into the prompt YAML file before parsing it as YAML. Since the diff/
diff-stat files started at column 0, injecting their multi-line
content broke the indentation of the enclosing `content: |-` block
scalar in changelog-entries.prompt.yml (which expects continuation
lines to be indented), causing "Failed to parse prompt file: bad
indentation of a mapping entry" at runtime, e.g.:
https://github.com/slack-ruby/slack-ruby-client/actions/runs/31552877245/job/93979138338
Indent every line of the diff/diff-stat files with 6 spaces (to
match the prompt file's block scalar indentation) before writing
them out, so the substituted content stays inside the block.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Danger ReportNo issues found. |
Coverage Report for CI Build 31553155612Warning Build has drifted: This PR's base is out of sync with its target branch, so coverage data may include unrelated changes. Coverage remained the same at 91.055%Details
Uncovered ChangesNo uncovered changes found. Coverage RegressionsNo coverage regressions found. Coverage Stats
💛 - Coveralls |
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Problem
The
update_api.ymlworkflow's new AI CHANGELOG generation step (#591) fails on the first real scheduled run:https://github.com/slack-ruby/slack-ruby-client/actions/runs/31552877245/job/93979138338
Root cause
actions/ai-inference@v1substitutes{{diff_stat}}/{{diff}}placeholders as raw text into the prompt YAML file before parsing it as YAML. The diff/diff-stat files were written starting at column 0, so injecting their multi-line content broke the indentation of the enclosingcontent: |-block scalar inchangelog-entries.prompt.yml.Fix
Pipe the diff/diff-stat output through
sed 's/^/ /'(6 spaces, matching the prompt file's block scalar indentation) before writing them to the files consumed viafile_input, so the substituted content stays inside the block and parses correctly.Verified by simulating the exact template substitution locally with
yaml.safe_loadafter applying the fix.