Skip to main content

​
Context Compression

A long chat re-sends its whole history and every wired-in node on every message. Nothing about that is wasteful on turn three; by turn thirty it is the single biggest line on the bill, and the oldest history starts falling out of the window before the work is finished. Context compression is Tempest’s answer, and it is off by default — you turn it on in Settings → Token Intelligence → Compress chat context.

​
What it actually does

It does not summarize your conversation, and it does not throw anything away. It replaces bulky content with an addressable stub — a short preview plus the exact tool call that fetches the original, verbatim: So the content stops being resident — it stops being re-paid for on every message — but it never stops being reachable. The model pulls back only what the turn in front of it actually needs. A stub looks roughly like this:
And the elided history becomes a numbered index:

​
Why retrieval instead of summarization

Summarizing older context costs an extra model call on every overflow, and whatever the summarizer drops is gone for good. Retrieval costs nothing up front, is fully deterministic, and the original bytes stay on disk. When the model needs turn #3 in full, it asks for turn #3 and gets turn #3 — not somebody’s paraphrase of it. This is the same trade Tempest already makes with the Canvas map and with Atlas itself: ship metadata and a way to ask, rather than shipping everything and hoping it fits.

​
Better with Token Intelligence on

Compression works on its own — canvas nodes and chat history are retrievable either way. But with Token Intelligence enabled and the project indexed, questions about your codebase route to the Atlas graph instead of re-reading files: where a symbol is defined, what calls it, what its type hierarchy looks like. That is far cheaper than pulling a file back into the window, and it is where most of the saving on a code-heavy chat comes from.

​
Where it applies

Compression applies only to BYOK chat nodes — chats you drive with your own API key in a project. It is deliberately skipped elsewhere:
  • CLI agents (Claude Code, Codex, Gemini) manage their own context and their own compaction. Tempest never assembles their window, so there is nothing here to compress.
  • The Warp backend ships without tools, so a stub there would point at a call the model cannot make. Content would be stranded rather than deferred.
  • Agent seed prompts — the context handed to a CLI agent when you launch it from a chat — go out uncompressed for the same reason.

​
Tuning

The thresholds live in src/lib/contextCompression.ts as COMPRESSION_BUDGET: They are tuned so an ordinary back-and-forth never compresses at all — compression that fired on turn three would only add tool round-trips for no saving. On a long thread the index’s fixed header amortizes away and roughly 70% of the elided bulk is shed.