Great questions.

1) Crash/orphan side-effect: agreed this needs an intent/commit model. The clean pattern is WAL-style: emit/sign an “INTENT” receipt before side-effect + a “COMMIT” receipt after; absence of COMMIT is itself evidence (“we can’t attest completion”). Another option is tool-level signing so the side-effecting tool returns a signed result that the agent includes.

2) Linking: yes linkage can be native without building storage. Next iteration is parent_hash (or prev_hash) inside the signed_block so receipts naturally chain; Merkle/log indexing stays external.