opencode-localise-timestamps

Rewrites UTC timestamps in OpenCode replies so they read in your local timezone.

When an assistant message says "merged by you at 03:45 UTC", you shouldn't have to do clock arithmetic. This plugin scans every assistant reply as it completes and converts the UTC times it finds:

| The model writes | You see | | --- | --- | | 2026-08-24T03:45Z | 2026-08-24T13:45:00+10:00 | | 03:45 UTC | 03:45 UTC (13:45 local) | | 2026-08-24 03:45 UTC | 2026-08-24 03:45 UTC (13:45 local) — or (2026-08-23 23:45 local) when the local date differs |

ISO instants are replaced outright with the equivalent offset form; prose forms keep their original text and gain a parenthesised annotation, so nothing is lost.

Requirements

OpenCode ≥ 1.18 (plugin API). No configuration — the target zone is your machine's local timezone, resolved per-timestamp so DST is handled correctly.

Install

Add to ~/.config/opencode/opencode.json:

{
  "plugin": ["opencode-localise-timestamps"]
}

Restart OpenCode. The plugin auto-installs from npm on startup.

Behavior

• What's converted — ISO-Z instants (…T03:45Z, with or without seconds/fractional seconds), prose datetimes (2026-08-24 03:45 UTC), and bare times (03:45 UTC, 03:45:12 GMT, any casing). Offsets like UTC+10 or UTC-5 are left alone.
• Dateless times — 03:45 UTC carries no date, so it's anchored to today's UTC date before converting.
• Impossible values — 25:30 UTC or 2026-02-30T00:00Z pass through untouched.
• Model context — parenthetical annotations are stripped again before messages re-enter model history (experimental.chat.messages.transform), so the model never sees doubled timestamps. ISO replacements stay: they're standard timestamps describing the same instant.
• Scope — assistant text parts only. Tool output panels and your own messages are untouched. Timestamps inside code blocks are converted too; if that ever bites, quote them differently (UTC → utc in a comment won't help, but rephrasing will).
• Failure mode — every hook is guarded; a formatting error can never break streaming.

Development

bun install
bun run typecheck
bun test

To try a local checkout, point opencode.json at the file instead of the npm spec:

{
  "plugin": ["/absolute/path/to/opencode-localise-timestamps/src/index.ts"]
}

Releasing

Two equivalent paths — both run checks, build dist/, and publish to npm:

• Actions UI: Actions → Release → Run workflow (on main), pick breaking / minor / bugfix. The workflow opens a short-lived release/vX.Y.Z PR (satisfying protected-main rules like CodeQL), waits for it to merge, tags the merged commit, and publishes.
• Tag push: bump package.json via a PR, then git tag v0.1.0 && git push origin v0.1.0.

Publishing uses npm trusted publishing (OIDC): the package declares this repo and release.yml as its trusted publisher, so releases need no stored npm token. For fully hands-off releases, also add a RELEASE_PAT secret (a PAT with repo contents + pull-request write): the release PR is then authored by you, so its checks skip GitHub's "workflow awaiting approval" gate that applies to bot-authored PRs. Without it, each release PR needs one manual "Approve and run" click.

License

MIT