🐛 Fixed block scalars being added to downloaded redirects

[allouis]

ref ONC-1827

Problem

Downloading redirects as YAML rewrote long URL values into >- folded block scalars that the user never authored:

301:
  /old/: >-
    /very/long/destination/path/that/is/definitely/longer/than/eighty/characters/

This didn't break redirects, but it injected undocumented markup into the user's file, causing confusion (reported by a customer who edited the markup out, re-uploaded, and saw Ghost add it back on the next download).

Root cause

serializeToYaml in redirect-config-parser.ts calls yaml.dump(), which defaults to js-yaml's lineWidth: 80. Any value longer than 80 chars gets folded into a block scalar.

Fix

Pass {lineWidth: -1} to disable line folding, so values are emitted verbatim on a single line. Values containing real newlines still use a literal block scalar (|-) and round-trip correctly through parseYaml.

Testing

Added a red/green unit test (does not fold long values into block scalars) asserting a long to URL produces no >- markup and round-trips intact. Verified the test fails without the fix and passes with it. All 23 redirect-config-parser tests pass.

🤖 Generated with Claude Code

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between e28d63b and fa7c301.

📒 Files selected for processing (2)

• ghost/core/core/server/services/custom-redirects/redirect-config-parser.ts
• ghost/core/test/unit/server/services/custom-redirects/redirect-config-parser.test.ts

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Walkthrough

This PR fixes YAML serialization in the redirect config parser by disabling line folding. The formatSection function now passes { lineWidth: -1 } to yaml.dump(), which prevents long URL and value strings from being rewritten into folded block scalar syntax. A new test verifies that long redirect target values are emitted without folding and that the resulting YAML parses back correctly.

Possibly related PRs

• TryGhost/Ghost#27697: Both PRs modify YAML serialization in redirect-config-parser.ts and add unit coverage to ensure long redirect values aren't YAML-folded.

Suggested reviewers

• vershwal

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title directly describes the main fix: preventing unwanted block scalar markup from being added to downloaded YAML redirects, which matches the core change in the PR.
Description check	✅ Passed	The description is clearly related to the changeset, explaining the problem, root cause, fix implementation, and testing approach for the redirect configuration parser changes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fabien-onc-1827-block-scalars-being-added-to-redirects

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