Raising the dead

How seances lead to better sleep

I still remember the first time I played Doom. It seems ridiculous now, but I remember that feeling of amazement: my computer can produce these incredible graphics? Wow.

I spent the evening addicted. And terrified. I wanted to stop; I didn’t enjoy the jump-scares. Or the ominous growling. But I couldn’t. It was 2am by the time I went to bed for a restless night dreaming of cacodaemons, imps and melting down as I died over and over.

My Doom experience - and an ill-judged late night viewing of Nightmare on Elm Street - have put me off anything to do with the dead. So it was a surprise when I found myself enthusiastically taking part in a necromantic seance last week.

Yes. Really.

Background

Claude Code, Codex and Gemini all store session logs. These are the logs that enable the "resume" commands to work - they are the complete set of agent & user messages for any particular session. Load them up and you can continue from where you left off.

They are just text, but I have gigabytes of them going back to last September (the harnesses now try to purge them, but I’ve got a tool that saves them for me).

But it suddenly occurred to me - they also document all my interactions with every agent. These logs contain valuable information. What skills were used. What prompts. What went well. What didn’t.

There is gold in them thar trees, sorry, logs.

But how to mine it? That is where my necromantic seance came in. I can just pick an old session, load it into Claude (or Codex) and suddenly that long dead instance comes back to life. It can answer questions about itself. Reflect on what it did. Opine on what would have made things better. Cool.

Over the past few weeks I’ve completely overhauled our dev processes. Finding out how well this had gone would be useful. And interesting. Maybe I could ask our sessions from before and after the changes?

A plan rapidly formed. Choose 666 sessions at random. Get Claude to reanimate them (either as Claude or Codex subagents based on what the original subagent had been), interview them, collect the data. And then lay them back down to rest peacefully.

Unfortunately token limits made 666 unworkable. So we settled on 120 for no particularly good reason other than it was a lot less than 666.

And here is the result:

In general the agents liked working on my projects (phew - I want a happy team). But the reanimated agents had asks. Codex wanted a proper ranged file-read tool. Everyone wanted a fix to my multi-agent prompt passing skill. Others complained about my worktrees-always rule.

The former is a surprise to me, but appears genuinely real. The tools Codex has to read from files on Windows are, well, not very good. Having to slowly page through a 30,000 line file seems just, well, daft. Claude Code has solved this problem (it has a custom tool), but Codex seems not to care. Perhaps this is because Codex is focused on the Mac/WSL world?

In any case we set to work building a new read tool. And involved the necromantic agents - who were delighted to provide feedback.

And soon a new tool rolled out across my fleet. After a few days of running I asked for feedback; it hadn’t had a lot of coverage yet, but there was only positive feedback - it fitted the use case Codex wanted. Probably not a surprise, given Codex designed it.

And the other pieces of feedback? We fixed the prompt passing skill. And we briefly tried no-worktrees-but-only-for-docs. However that rapidly descended into chaos, so we’re back with worktree-always plus some rationale in agents.md/claude.md to explain why this is the right approach.

And so?

In many ways this is like a retro; reflect on what you’ve done, identify concrete changes and then implement them. But a retro is different. It involves humans with their fuzzy memories. With an agentic seance you can go back and ask the agents exactly what they were thinking. No time-induced-fuzziness.

Plus it’s automatable. My agents are planning to hold a seance every fortnight. They’ll produce a list of reqs and decide what to add to the reqs build queue. And, all being well, if they are accepted they’ll get built and shipped. For now there are (quite a few) human gates in the way, but as I increasingly trust the agents (and get better at setting the rules for when they need to ask me), I plan to step back. Introspection, self-improvement, is suddenly possible. Whether this makes things better or takes us down a dark hole where the agents decide to do something other than build software is an interesting question - I’m sure I’ll find out.

For now, though, the benefit of these seances - this self-improvement loop - is that I’m required less. Perhaps, for once, interacting with the dead will lead to better sleep.