feat: report Code Mower setup drift

README.md

@@ -71,6 +71,12 @@ boundaries visible before you promote any reviewer lane.
 
 See a fuller static transcript: [docs/first-run-transcript.md](docs/first-run-transcript.md).
 
+For an existing repository that already has Code Mower generated workflows or
+wrappers, run `code-mower migration setup-drift --repo-path .` before copying a
+fresh `.code-mower.generated` tree. It is read-only and reports path-level
+classifications (`same`, `differs`, `new`, `repo-only`,
+`missing-from-output`) without file contents or diffs.
+
 After `init` and `doctor`, use `code-mower lanes status --repo OWNER/REPO` to
 see active builder/reviewer lanes, gate/check state, recent Code Mower
 workflows, local board/process hints when present, and the next operator

docs/install.md

@@ -157,7 +157,10 @@ secret values, or secrets.
 
 ## First Repository Commands
 
-After install, start with the manual reviewer-gate path:
+After install, choose the path that matches the repository.
+
+For a cold repository that has not adopted Code Mower, start with the manual
+reviewer-gate path:
 
 ```bash
 code-mower init --easy
@@ -166,6 +169,19 @@ code-mower lanes status --repo OWNER/REPO
 code-mower board serve --repo OWNER/REPO
 ```
 
+For an existing repository with older Code Mower generated files, inspect drift
+before copying a newly generated tree into the repo:
+
+```bash
+code-mower migration setup-drift --repo-path . --json
+code-mower migration setup-drift --repo-path .
+```
+
+The drift report is read-only. It compares the current generated setup output
+against tracked Code Mower files and classifies paths as `same`, `differs`,
+`new`, `repo-only`, or `missing-from-output`. Use it before an upgrade PR so
+you can review workflow/wrapper changes without source diffs in the report.
+
 If this machine is a hosted-builder observer or orchestrator only, and will not
 run Codex or Claude local CLI audits itself, keep the GitHub/cloud/setup checks
 but skip local CLI probes: