OpenAI ships experimental compaction for GPT-6 Astra in Codex: notes persist across context windows

On September 5, danielmac8 disclosed that OpenAI shipped a new compaction mechanism for GPT-6 Astra in Codex. It is experimental, off by default, and must be enabled manually. Once enabled, the model can save key information as "notes" that persist across context windows instead of being lost with old ones; earlier context windows, including messages and tool-call records, also become searchable rather than being repeatedly compressed into a single summary. danielmac8 argues this stops the model from behaving like an amnesiac.

Confirmed

The feature is live in Codex, experimental, off by default, and requires manual enabling (m2/m3/m4)
Two core capabilities: notes saved across context windows; earlier context (messages and tool calls) becomes searchable (m2/m3/m4)
The goal is to stop information from being lost through repeated compression once the context window fills up (m2/m5)

Why it matters

VraserX (m5) calls it Astra's most important yet least flashy feature: seemingly plumbing-level work, but a key step toward letting long-running agents accumulate state over time
Persistent cross-window memory means long-task agents no longer "forget," which matters for complex multi-step workflows

2026-09-04 ~ 2026-09-05 · 5 related posts

Full story(2 episodes)→

Episode 1: OpenAI ships experimental compaction for GPT-6 Astra in Codex: notes persist across context windows(2026-09-04, 5 posts)
Episode 2: Codex's Astra Keeps Notes Across Context Windows and Makes History Searchable(2026-09-05, 4 posts)

Primary sources

GPT-6 Astra's Codex compaction: persistent notes and searchable past contexts — daniel_mac8 · 2026-09-05 02:08 (UTC+08:00)
Codex launches Astra: notes that persist across context windows — gabrielchua · 2026-09-05 12:44 (UTC+08:00)
GPT-6 Astra's quiet superpower: persistent notes and searchable context across windows — VraserX · 2026-09-04 12:08 (UTC+08:00)

[source] GPT-6 Astra's quiet superpower: persistent notes and searchable context across windows — VraserX · 2026-09-04
[source] GPT-6 Astra's Codex compaction: persistent notes and searchable past contexts — daniel_mac8 · 2026-09-05
GPT-6 Astra's experimental compaction in Codex saves notes across context windows, off by default — TheMoonMidas · 2026-09-05
[source] Codex launches Astra: notes that persist across context windows — gabrielchua · 2026-09-05

1 near-duplicate retellings: daniel_mac8