session-ledgerlisted

# Session Ledger: reasoning that survives compaction When a session grows long, the harness summarises the earlier turns. Root instruction files and the memory index are re-read from disk and survive intact. **Your reasoning does not.** The summary keeps roughly what happened; it loses why. The decision you locked after twenty minutes of argument, the fact you verified with a specific command, the approach you abandoned for a good reason: all of that becomes prose, or vanishes. The cost is not the lost text. It is that a later turn re-opens a settled question, re-verifies a proven fact, or retries an abandoned path, and nobody notices, because the record of the decision went with the summary. The Session Ledger is a small file that holds exactly the state a summary destroys, and nothing that a summary preserves or that one command can recompute. ## The one rule that shapes everything **Preserve only what is not cheaply re-derivable.** Your git branch, the open pull requests, the todo list, the build status: these are one command away, always current, and never worth carrying. They are re-derived after compaction, not preserved. Decisions, rationale, verification provenance, and dead ends cannot be recomputed from anything. Once the summary flattens them, they are gone. Those are the ledger's only business. A ledger that fills up with status snapshots has become the thing it was built to replace. ## The contract with the harness Three facts govern the design. They ar