Implement ADR-0007

docs/cli.md

@@ -29,7 +29,8 @@ Flags:
   rules in [Configuration](config.md#discovery).
 - `--only lane-a,lane-b`: run only the named artifact lanes. Values are
   comma-separated and must be non-empty.
-- `--resume`: request checkpoint reuse for this invocation. See
+- `--resume`: request checkpoint reuse for this invocation. Checkpoint recording
+  must be enabled in configuration. See
   [Operations](operations.md#checkpoint-cache) for prerequisites and reuse
   behavior.
 - `--chunk_cache auto|bypass|refresh`: select chunk-plan reuse for this
@@ -124,9 +125,9 @@ go run ./cmd/notarius run dnd-session \
   --session-id campaign-17-session-04
 ```
 
-The resume flag can be added to an otherwise identical run invocation. It both
-loads compatible checkpoints and records replacements for work executed by that
-invocation; without it, the checkpoint root is not used:
+When `cache.checkpoints.enabled` is `true`, runs record checkpoints whether or
+not `--resume` is present. Add the resume flag to load and reuse compatible
+recorded work; using it while checkpoint recording is disabled is an error:
 
 ```sh
 go run ./cmd/notarius run dnd-session \