[SandObserver]

Summary

• Condense every entry in the released sections (1.5.1 and earlier) to the change itself, dropping the trailing rationale. The file's stated rule is one minimal imperative line, with a second only when the reader must take an action; entries that name an action keep that sentence.
• Normalise the blank lines between bullets, which the file mixed.
• 645 lines to 517. Average entry length 24 words to 18. The worst section, 1.5.0, was 297 lines across 96 entries.

Verified mechanically rather than by eye: all 205 entries are still present, every surviving entry's opening statement appears verbatim in the previous revision, and no entry was merged, dropped or reworded into something new. Version headings, dates, the Keep a Changelog and Semantic Versioning links, and every compare link at the bottom are untouched.

Testing
All green. No new tests: documentation only.

Checklist

• Stays within the project constraints: one container, no runtime dependencies, no build step (see CONTRIBUTING.md).
• Tests added or updated for new logic, and the full suite, lint, and typechecks pass.
• Docs updated if behavior or configuration changed.
• CHANGELOG.md updated under Unreleased if the change is user-visible.