docs: refine downstream onboarding workflow

docs/downstream-onboarding-playbook.md

@@ -27,6 +27,14 @@ This gives AI agents a durable provenance model:
 Do not stage onboarding from `.minions-template.next/`; that path is for later
 upgrade candidates.
 
+The vendored snapshot is an export-ready copy of the template, not a full Git
+clone.
+
+- exclude `.git/`
+- exclude files marked `do-not-export` in `docs/export-manifest.md`
+- `.mm.md` should not appear in `.minions-template/` unless the Operator
+  intentionally chooses to carry MM context downstream
+
 ## Ownership
 
 - `PM` owns the onboarding export packet and Operator-facing checklist
@@ -40,7 +48,10 @@ upgrade candidates.
 
 ## Onboarding Workflow
 
-1. Copy the template repo into `.minions-template/` unchanged.
+1. Create `.minions-template/` as an export-ready snapshot of the template:
+   - copy the files needed for onboarding and future upgrades
+   - do not carry Git metadata such as `.git/`
+   - do not carry `do-not-export` files such as `.mm.md`
 2. Review `docs/export-manifest.md` before exporting any live files.
 3. Export `template-replace` files from `.minions-template/` into the live
    downstream repo.
@@ -50,8 +61,8 @@ upgrade candidates.
    - `MEMORY.md`
    - `docs/operator-onboarding-checklist.md`
    - `minion-version.md`
-5. Do not export `do-not-export` files such as `.mm.md` unless the Operator
-   explicitly wants them downstream.
+5. Do not export `do-not-export` files, and do not keep them in the vendored
+   snapshot, unless the Operator explicitly wants them downstream.
 6. Treat downstream-owned files as project surfaces, not template clones:
    - project `README.md`
    - live plans
@@ -94,6 +105,7 @@ upgrade candidates.
 
 - template version being onboarded
 - vendored snapshot path
+- confirmation that `.git/` and `do-not-export` files were excluded from the vendored snapshot
 - files exported directly from template
 - files manually merged for downstream use
 - files intentionally left downstream-owned