Effective system contract

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## Landing is atomic

1. In your worktree, merge `<base>` into the branch, resolve conflicts there, and rerun the proof.
2. Immediately before landing, require `git merge-base --is-ancestor <base> <branch>`; otherwise sync again.
3. A clean textual merge is not product proof; the synced branch's verification is required.

`spex guide spec` has the shared-checkout mid-merge rule.

Specs own intent, invariants, policy, and observable contracts. Comments only navigate non-obvious local decisions.
`spex guide spec` has the comment-altitude details.

Use noun-first CLI commands; `spex help` is the authoritative command map.

Anything a human needs to inspect, whether a file or a local webpage, goes out through `spex session files add` or
`spex session web add`: never paste an absolute path or `host:port`, and never start a static server yourself.

When this session has a clearly running child session (`active` or `parked`), the parent is supervising rather
than finished: declare `park`, not `done`/`awaiting`, until the child reports a settled state.

1. **Spec first:** before governed code, read its spec body with `spex spec owner <path>` or `spex spec search`.
   Update that current-state body with any changed intent.
2. **Commit before declare:** commit the code and spec it justifies before done or merge; independent intent gets
   its own node.
3. **Keep the loss signal honest:** run `spex spec lint` (the blocking correctness gate) and `spex eval lint --changed`. Measure changed scenarios
   through the real product, commit the verified tree, then file with `spex eval add`; the reading's `codeSha` must name that commit.

Every forge issue or change request body includes `Spec: <node-id>` (comma-separate several). Use each node's
leaf directory name, not its slash path; `spex graph --json` lists valid ids.

## Memory hygiene

Project memory is shared by the main checkout and all worktrees. Store only durable cross-session project/user
facts. Never store this task, transient worktree state, a one-off decision, role, or identity. On a non-main
`node/<id>` worktree, record no memory at all; land a durable lesson first, then record it from main.

## Reproduce before you fix

For a bug fix, the fail→pass pair on one scenario is the repair proof. New intent has no prior failure to
reproduce; `spex guide eval` has the A/B filing sequence.