Claude Code and Codex start every session blank. Here's how to fix it

The issue, as reported

On the Codex issue tracker, an open report from 14 September describes what happens after a usage limit cuts off a long task. When the task is resumed, Codex spends a large part of the new allowance rebuilding what it already knew: re-reading repository files, rerunning checks and tests, and working out again which steps are finished. The developer now writes handoff summaries by hand so that Codex doesn't redo completed work.

Claude Code users describe the same thing. At the end of August, a developer on r/ClaudeAI who runs eight Claude Code sessions, restarted each night by a scheduled job, said the agents started every morning with no idea what they had been doing, and had to be re-briefed from a phone. Their fix was a handoff file and a start-up hook, which is where the free fix below comes from.

The harder loss is what was learned along the way. A feature request on the Claude Code tracker, opened in August and still drawing replies in late September (21 so far), points out that after an agent spends a long time debugging a problem, what was tried, what failed and why it worked is hard to carry into the next session. Developers keep it by hand in CLAUDE.md, or explain it again.

Built-in memory helps, but heavy users hit its edges. One open request describes a project with around 500 memory files where Claude Code's index limit has become a constant ceiling. On the Codex side, a report from 26 September says that archiving a finished chat before Codex gets round to it means the work in it never becomes a memory at all.

Why it happens

The model keeps nothing between sessions. Anthropic's documentation says it directly: each Claude Code session begins with a fresh context window. What the agent knows at the start comes from files loaded at launch, plus whatever it reads as it works.

Two kinds of file are loaded:

• Instructions you write. Claude Code loads CLAUDE.md, and can read AGENTS.md; Codex reads AGENTS.md before doing any work.
• Notes the tool writes. Claude Code's auto memory is on by default and loads only the first 200 lines or 25KB of its MEMORY.md index. It is machine-local, and it skips anything it can derive from the code, "such as architecture, file paths, or debugging fixes". Codex's local memories are off by default; once on, Codex skips active or short-lived chats and waits until a chat has been idle before summarising it. OpenAI's advice is to treat them as "a helpful recall layer, not as the only source for rules that must always apply".

The full conversations, which hold the reasons and the failed attempts, are saved on disk (Claude Code keeps them as JSONL files), but a new session doesn't read them. You can reopen one conversation at a time. So a fresh session gets the rules you wrote plus a short, capped summary for one tool on one machine, and that is the gap the reports above describe.

How to fix it today

These steps need nothing beyond the tools themselves, and follow their current official docs.

1. Put what's settled in AGENTS.md

   Claude Code v2.1.277 and later reads AGENTS.md too, when the project has no CLAUDE.md. If you have both, put @AGENTS.md on the first line of CLAUDE.md so one file serves both tools. Keep it under 200 lines: the Claude Code docs say longer files use more context and are followed less reliably. Put in build and test commands, what not to touch, and one line per settled decision with its reason. In Claude Code, run /context and check Memory files to confirm it loaded.

2. Keep a handoff file

   One small file in the project root, rewritten at each milestone. Ask the agent to update it before you stop:

   NOW      auth refactor, step 3 of 5
   NEXT     move token refresh into middleware
   DECIDED  Postgres, not SQLite (reporting joins)
   FAILED   retry wrapper: made timeouts worse
   DON'T    touch /migrations

3. Load it automatically in Claude Code

   A SessionStart hook runs when a session starts, resumes, is cleared or is compacted, and Claude Code adds its plain output to the context. Add the snippet below to .claude/settings.json. The args form is what the docs recommend when a hook uses a path placeholder (this one assumes macOS or Linux). Keep the file in place, even empty, so the hook always has something to read. In Codex, add a line to AGENTS.md asking it to read HANDOFF.md first.

   {
     "hooks": {
       "SessionStart": [
         {
           "matcher": "startup|resume|clear|compact",
           "hooks": [
             {
               "type": "command",
               "command": "cat",
               "args": ["${CLAUDE_PROJECT_DIR}/HANDOFF.md"]
             }
           ]
         }
       ]
     }
   }

4. Turn on Codex memories

   Local memories are off by default. Turn them on in the ChatGPT desktop app under Settings > Personalization > Enable memories, or add this to config.toml:

   [features]
   memories = true

5. Resume when you're continuing the same task

   claude --continue reopens the last conversation in the directory, claude --resume opens a picker, and codex resume reopens a recent chat. When you resume a long session that has been idle for about an hour, Claude Code may offer to resume from a summary. Choose the full session when the details matter: the docs note that whatever the summary leaves out is no longer in context.

What the fix doesn't cover

How Axiom Lift solves it

Axiom Lift works from the full conversations rather than a summary you have to maintain.

What it doesn't do: it doesn't replace AGENTS.md or CLAUDE.md for rules that must always apply, and it can't make a model follow anything. It doesn't cover Cursor, or ChatGPT and Claude in a browser. On the free plan, your AI can reach the last six months of history.

Install is one command in a desktop terminal (Mac; Linux and Windows in beta; needs Python 3). It shows you what it found before anything is sent, it's free, and axiom uninstall removes it.

Claude, Codex and OpenCode are trademarks of their owners; Axiom works alongside them and is not affiliated.