Playbook 07: a feature worktree needs the siblings the lab reads

A bed run from .work/<slug>/mesh-lab derives mesh-tools and mesh-sdk by
sibling path and fails at once when the directory holds only the touched
repos. Detached worktrees on main, never symlinks.

00-META/process/07-feature-branches.md

@@ -28,6 +28,16 @@ One feature is **one branch name**, **one worktree per repo**, **one MR per repo
    git worktree add .work/<slug>/<repo> -b feat/<slug> origin/main
    ```
    Parallel features never collide, and no shared checkout is edited.
+
+   **Add the untouched siblings the lab reads.** The lab beds find the other repositories by
+   sibling path from the lab checkout (`../mesh-tools/module.json`, `../mesh-sdk`, …), the way
+   the main layout has them. A `.work/<slug>/` directory holding only the touched repos fails a
+   bed at once with `no manifest for mesh-tools at …/.work/<slug>/mesh-tools/module.json`, after
+   genesis has already passed. Give the directory those repos as **detached worktrees on `main`**
+   — never symlinks:
+   ```
+   git worktree add --detach .work/<slug>/mesh-tools main
+   ```
 3. **Commit as you go — locally.** Increments land on the one branch. Nothing is pushed and no
    MR is opened mid-feature.
 4. **Finish, then publish.** When the whole feature is done — every repo, tests green — push
@@ -52,6 +62,8 @@ The end state is visible, and its absence is the smell:
 
 - After a feature merges, `git branch -r | grep feat/<slug>` and `git worktree list` return
   nothing for it. A surviving branch or worktree means step 6 was skipped.
+- A bed run from `.work/<slug>/mesh-lab` that fails naming a `.work/<slug>/<repo>/…` path it
+  cannot find is a missing sibling worktree, not a mesh fault.
 - More than one open MR in a repo that share no feature name, or a stack of MRs none of which is
   merged, is the failure this playbook exists to prevent — stop and consolidate before opening
   more.