[vincentvandeth]

Great questions. I've been running ~2,400 multi-agent dispatches across 4 terminals (different AI models) for about 6 months, so I'll share what I've hit in practice rather than theory.

On RFC 3161 vs. multi-witness anchoring: For most production agent systems today, RFC 3161-style timestamping is overkill — and so is multi-witness anchoring. The practical threat model isn't a sophisticated adversary backdating entries. It's your own agents producing self-consistent but wrong output, and you not being able to reconstruct the sequence after the fact. The real defensibility problem is completeness, not tamper-proofing. Can you prove nothing was omitted? That's harder than proving nothing was altered. I use an external watcher process that observes agent output independently — the agent doesn't write to the log, so it can't selectively omit entries. That separation does more for defensibility than any cryptographic anchoring would at my scale.

On replayability: It breaks down the moment you involve external state. An agent that reads a file, calls an API, or queries a database — the inputs to that decision are gone unless you explicitly snapshot them. Git shows what changed, but not what the agent saw when it decided to change it. Chat sessions expire. CoT gets truncated. I capture pre-state and post-state per dispatch, but the reasoning trace between them is still the weakest link. Nobody I've seen solves this cleanly yet. The best workaround I've found: treat the agent's self-reported reasoning as one input, but verify it against an independent quality check (separate process the agent can't influence). You can't replay the reasoning, but you can independently verify the outcome.

On the overengineering threshold: For me it became necessary after about 200 dispatches. One of my agents hallucinated a dependency, a second agent "fixed" the resulting test failures by creating the missing module, and by morning I had three rewritten files with clean commits built on something that should never have existed. The scary part wasn't the mistake — it was that I couldn't reconstruct why it happened. At single-agent scale, you can eyeball diffs. The moment you have agents responding to each other's output, forensic reconstruction stops being optional. I'd say the threshold is: if agent A's output can trigger agent B's action without human review, you need defensible logs. Not because of litigation risk, but because you literally can't debug cascading failures without them.