Feature: Message labels — named checkpoints for resuming and forking chats

[ovistoica]

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Context

Spawned from #388.

Problem

When building up context in a chat — loading skills, giving project background, establishing a working baseline — there is no way to bookmark that point. If I want to reuse that exact context in a new session a week later, I have to rebuild it from scratch. The longer and more involved the setup, the more painful this is.

This also means prompt caching benefits are lost. With Anthropic, a well-cached context prefix is extremely valuable — but only if you can actually resume from it.

Proposed solution: message labels

Allow the user to attach a named label to any message in the chat history. A labeled message acts as a named checkpoint that can be resumed or forked from directly.

Example workflow:

1. Start a chat
2. Load the skills and rules the agent needs
3. Give project-specific context and establish a working baseline
4. Label the last message: "Frontend agent — MyProject"

A week later, when frontend work comes up again:

• Resume or fork directly from "Frontend agent — MyProject"
• The agent starts with the full cached context already in place
• No rebuilding, no re-explaining

What this is not

Labels are not a replacement for fork-from-any-message. Fork is point-in-time navigation; labels are named, intentional checkpoints that survive across sessions and are easy to discover and reuse. The labels should be searchable in eca-chat-timeline

Rough UX ideas

• /label <name> slash command to label the current message
• A label picker when starting /resume or /fork, showing named checkpoints alongside recent sessions
• Labels visible as markers in the chat buffer (similar to the tombstone in the compaction proposal)

Notes

• Labels should be stored server-side so they survive restarts and are available across clients
• A label could be as simple as a metadata field on the message record in the DB
• Pairs naturally with the compaction tombstone proposal: labeled checkpoints before a tombstone remain accessible even after compaction