TheOne

One chat for everything you're working on.
It knows which project each message belongs to, and keeps every project's context separate.

English | 简体中文

_{A GPU question, a hotel question, then the GPU again, with no cues in between. The two topics on the left made themselves; nothing was clicked. (Example conversation.)}

How many sessions are sitting in your DSH sidebar? Getting back to last week's work means digging through them. Skip creating a new one and everything piles into a single session, where topics bleed into each other and the details vanish at the next compaction.

If you've ever said any of these, TheOne was probably written for you:

• "Where was that chat again?" Too many conversations, and the old one is nowhere to be found.
• "Not starting a new chat for this, I'll just ask here." And one chat turns into a mess.
• "I already told you that!" The AI forgot what you talked about.

What TheOne does: you only ever talk in one main chat. In the background it opens a separate session for each thing you're working on and sends every message to the one it belongs to.

Each project reasons, runs tools and compacts in its own session. What you see is always one ordinary conversation.

Why try it

• Feels native. Thinking streams in its usual place from the first token, and tool cards, approvals, questions, todo lists, retries and mid-reply steering all work as usual.
• Related work connects; unrelated work stays out. Related topics share progress automatically, and which ones belong together is learned from how you use them. A topic's constraints (say, "budget figures stay out of the paper") are attached verbatim every time, so compaction never drops them.
• Learns your words. Once a topic has replies, a short routing card is written in the background (what it is, what you call it, the people, places and files involved), so it is recognised however you phrase it. Say "wrong topic" and it remembers which terms tie that kind of message to the right one. Topics you haven't touched in a long while go to the back of the line; how long is "long" is learned from how you come back to things.
• Your old sessions become a topic directory. After install it reads your existing sessions in the background, turns them into topics grouped into workspaces, and you pick up where you left off.
• Nothing extra to configure. No separate API key: it uses the model you chose in DSH. When TheOne is selected, a layers icon beside the model menu shows and switches which model routes and which does the work.

Install in 30 seconds

1. Configure an API in DSH and select a model that can chat.
2. Open Plugins → Add plugin, enter dsh-theone under Package name or address, and install.
3. Click TheOne · Main chat in the sidebar and start talking.

That's it. Works with DSH 0.2.0-rc.2 and Node.js 24; the interface follows DSH's language (English / Simplified Chinese).

Unofficial community project, maintained independently. It is not affiliated with or endorsed by DeepSeek.

How well does it route?

Claims are cheap, so we built a public benchmark, InterleaveBench: one person pushing 3–5 things forward in the same chat at once (a trip, a budget, a paper, a training plan…), half in Chinese and half in English, 50 conversations and 2,466 messages, each labelled in advance with the thing it belongs to. Below, the 40-conversation dev split replayed message by message through TheOne's own routing code with DeepSeek V4.1 Flash (messages even a careful human could not attribute are not scored):

A few numbers worth knowing:

• A message landing in another thing's topic, the mistake that hurts context most: about 3.7% when starting from nothing.
• The main weakness today is opening new topics too eagerly: one thing ends up split over 2.1 topics on average. 0.3.21's routing cards go after exactly that.
• The whole run cost about one US dollar. Data, code and scoring live in eval/; reproduce it, or try another model.

The conversations are model-written from a script and this version has no assistant replies, so it measures whether messages are routed right, not everything about how chatting feels.

What's next

For now, TheOne is being refined on DeepSeek Harness, whose background sessions, tools and compaction can be reused as they are: the right place to get "one chat for everything" solid first.

In progress:

• Better routing: looking at a burst of messages together while deciding each one separately, and measuring what routing cards add.
• Confirmed facts shared between topics: a budget, a date, where a file lives, kept current wherever you need it. It is experimental and will only be turned on by default once it passes its benchmark.

Once it is stable, the next step goes beyond DSH:

• A standalone client: one interface over different models and providers, opening straight into a single chat;
• or adapters for other platforms: the same automatic topics, inside the chat tools you already use.

Which comes first depends on what people need more. If you have a view, say so in Issues or by email at theone@yulid.org.

How it works

Choosing a topic. Each message is matched to the current topic, an earlier one, or a new one. By default the model you selected makes one short classification (thinking off, at most 2,048 tokens), with candidates recalled through DSH full-text search.

• With no credible match it starts a new topic instead of asking whether it is new. It only asks when you refer to an earlier chat it cannot find, or it truly cannot tell which one you mean.
• When one message draws on several topics, the one doing the work gets it and the others come along as reference.
• "ok" or "go on" continues the current topic without waiting for a decision, and so does a picture or file sent without words.
• If the classification call fails, rules decide, staying in the current topic when unsure. Rule-based routing (THEONE_ROUTER_MODE=rules) makes no model calls at all.

Linking topics. A background session starting work receives a reference briefing, and none when there is nothing new:

• right after a topic switch, the last few turns of main chat, so "use what we just said" carries over;
• what changed in related topics since it last heard: their latest compaction summary (dated) and the progress after it;
• each topic's constraints, verbatim, every time.

The briefing is marked as reference, not instructions. For details, the background session can use theone_read_topic and theone_search_history. Linking scope is Learn automatically (default), Same workspace only or Off. In the directory you can link or unlink topics and mark a topic Do not share; your choices always win.

Topic directory. Each topic shows its latest progress and constraints. Under Manage you can rename, edit the summary and constraints, move to another workspace, merge, delete, or attach an existing DSH session as searchable history; + New topic starts one by hand. Recent topic routing lists where each message went, why, with which model and how long it took. With a long history, the first pass takes some time and API quota; set THEONE_HISTORY_CATALOG=false to turn it off.

git clone https://github.com/YunongDai2005/dsh-theone.git
cd dsh-theone
npm ci --ignore-scripts
npm run typecheck
npm test

If TheOne helps, a ⭐ helps others find it. Questions or ideas? Open an issue or email theone@yulid.org.