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codex/codex-rs/core
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Charley Cunningham 143daadb31 core: refresh developer instructions after compaction replacement history (#10574)
## Summary

When replaying compacted history (especially `replacement_history` from
remote compaction), we should not keep stale developer messages from
older session state. This PR trims developer-
role messages from compacted replacement history and reinjects fresh
developer instructions derived from current turn/session state.

This aligns compaction replay behavior with the intended "fresh
instructions after summary" model.

## Problem

Compaction replay had two paths:

- `Compacted { replacement_history: None }`: rebuilt with fresh initial
context
- `Compacted { replacement_history: Some(...) }`: previously used raw
replacement history as-is

The second path could carry stale developer instructions
(permissions/personality/collab-mode guidance) across session changes.

## What Changed

### 1) Added helper to refresh compacted developer instructions

- **File:** `codex-rs/core/src/compact.rs`
- **Function:** `refresh_compacted_developer_instructions(...)`

Behavior:
- remove all `ResponseItem::Message { role: "developer", .. }` from
compacted history
- append fresh developer messages from current
`build_initial_context(...)`

### 2) Applied helper in remote compaction flow

- **File:** `codex-rs/core/src/compact_remote.rs`
- After receiving compact endpoint output, refresh developer
instructions before replacing history and persisting
`replacement_history`.

### 3) Applied helper while reconstructing history from rollout

- **File:** `codex-rs/core/src/codex.rs`
- In `reconstruct_history_from_rollout(...)`, when processing
`Compacted` entries with `replacement_history`, refresh developer
instructions instead of directly replacing with raw history.

## Non-Goals / Follow-up

This PR does **not** address the existing first-turn-after-resume
double-injection behavior.
A follow-up PR will handle resume-time dedup/idempotence separately.

If you want, I can also give you a shorter “squash-merge friendly”
version of the description.

## Codex author
`codex fork 019c25e6-706e-75d1-9198-688ec00a8256`
143daadb31 · 2026-02-06 12:25:08 -08:00
History
..
2026-01-20 14:02:07 -08:00
2026-01-23 00:44:47 +00:00

codex-core

This crate implements the business logic for Codex. It is designed to be used by the various Codex UIs written in Rust.

Dependencies

Note that codex-core makes some assumptions about certain helper utilities being available in the environment. Currently, this support matrix is:

macOS

Expects /usr/bin/sandbox-exec to be present.

When using the workspace-write sandbox policy, the Seatbelt profile allows writes under the configured writable roots while keeping .git (directory or pointer file), the resolved gitdir: target, and .codex read-only.

Linux

Expects the binary containing codex-core to run the equivalent of codex sandbox linux (legacy alias: codex debug landlock) when arg0 is codex-linux-sandbox. See the codex-arg0 crate for details.

All Platforms

Expects the binary containing codex-core to simulate the virtual apply_patch CLI when arg1 is --codex-run-as-apply-patch. See the codex-arg0 crate for details.