Files
coder/coderd/chatd/chatloop
Kyle Carberry 53bfbf7c03 fix(chatd): improve compaction prompt to preserve forward momentum (#22989)
## Problem

The summarization prompt explicitly tells the model to **"Omit
pleasantries and next-step suggestions"** and the summary prefix frames
the compacted context as passive history: `Summary of earlier chat
context:`. After compaction mid-task, the model reads a factual recap
with no forward momentum, loses its direction, and either stops or asks
the user what to do.

## Research

I compared our compaction prompt against several other agents:

| Agent | Key Pattern |
|---|---|
| **Codex** | Prompt says *"Include what remains to be done (clear next
steps)"*. Prefix: *"Another language model started to solve this
problem..."* |
| **Mux** | Includes *"Current state of the work (what's done, what's in
progress)"* + appends the user's follow-up intent |
| **Continue** | *"Make sure it is clear what the current stream of work
was at the very end prior to compaction so that you can continue exactly
where you left off"* |
| **Copilot Chat** | Dedicated sections for *Active Work State*, *Recent
Operations*, *Pre-Summary State*, and a *Continuation Plan* with
explicit next actions |

**Every other major agent explicitly preserves forward intent and
in-progress state.** Coder was the only one telling the model to omit
next steps.

## Changes

**Summary prompt:**
- Removes `Omit next-step suggestions`
- Adds structured `Include:` list with explicit items for in-progress
work, remaining work, and the specific action being performed when
compaction fired
- Frames the operation as `context compaction` (matching Codex's
framing)

**Summary prefix:**
- Old: `Summary of earlier chat context:`
- New: `The following is a summary of the earlier conversation. The
assistant was actively working when the context was compacted. Continue
the work described below:`

The prefix is the first thing the model reads post-compaction — framing
it as an active handoff with an explicit "Continue" directive primes the
model to resume work rather than wait.
2026-03-12 13:03:06 +00:00
..