Mark public ObjectMessage.id and .timestamp as optional

[lawrence-forooghian]

These declared types are incorrect since these values are not populated for ObjectMessages created by apply-on-ACK.

This is a breaking change to the type declarations, but I think it's the right thing to do given that the declarations do not match the runtime behaviour. You could argue that we could try and fix the runtime behaviour; i.e backfill timestamp based on the server time or something, but I'm not sure it'd be easy to backfill id. Thoughts welcome.

Noticed this whilst working on the spec for the path-based API in ably/specification#427; see PAOM2a/d there. I've incorporated the API change from the current commit into those points.

Summary by CodeRabbit

• Refactor
  • Object messages no longer require an id or timestamp — these fields may be omitted. This makes message handling more tolerant of missing identifiers or time values.

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 186a0337-806d-4c54-b217-cdc34d1bc823

📥 Commits

Reviewing files that changed from the base of the PR and between 02ac44b and 7552659.

📒 Files selected for processing (2)

• liveobjects.d.ts
• src/plugins/liveobjects/objectmessage.ts

---

Walkthrough

ObjectMessage type marks id and timestamp as optional, and the toUserFacingMessage() method no longer uses non-null assertions for id, clientId, connectionId, and timestamp, allowing them to be undefined.

Changes

ObjectMessage field optionality

Layer / File(s)	Summary
ObjectMessage interface optionality liveobjects.d.ts	ObjectMessage.id and ObjectMessage.timestamp fields transition from required to optional types.
Optionality implementation update src/plugins/liveobjects/objectmessage.ts	toUserFacingMessage() removes non-null assertions (!) from id, clientId, connectionId, and timestamp fields to align with the optional interface contract.

🎯 2 (Simple) | ⏱️ ~10 minutes

🐰 I nudged two fields to gently roam,
No bangs to force them from their home,
If missing, they'll softly be unknown,
Lightweight change — a hop, then home 🥕

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: making ObjectMessage.id and .timestamp optional in the public type declarations.
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.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ 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 2026-05-22-objectmessage-public-type-nullability

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}