Adds the migration plan and its phase files, the parity report, and the code
review.
Annotates the two records this work supersedes rather than rewriting them: the
2026-09-18 language-choice research, whose first recommendation was to keep the
engine in Go and was overridden the same day, and the 2026-08-18 plan that
produced that engine. Both bodies are left as written, since erasing them would
destroy the reasoning a future reader needs.
Six success criteria stay unticked with the reason inline: they need a push, a
GitHub token, or a Codex run to verify.
The duplicate-check boundary set had '<' but not '>', so a URL stored
as <https://…> (autolink, used by older posts) was never detected as a
duplicate. Inherited from the JS engine; found while validating the Go
port against 2020-era posts.
One Go binary with a subcommand per former script, invoked as
'go run ./scripts/newsletter <command>' from repo root. Stdlib only;
publications config embedded via go:embed (go run recompiles on edit).
Behavior parity verified side-by-side before deleting the JS —
see plans/reports/parity-260818-newsletter-go-migration-report.md.
Permissions: allow 'Bash(go *)', drop 'Bash(node *)' and the redundant
'Write(content)' rule (Edit rules cover all file-editing tools).
tiennm99