Playbook 07: the lead writes a design's state back (issue 1009)

Design 57 was merged as a release with three tasks left and still said
designed, so another session took it for unbuilt. Say it in-progress, with
what is left and when it is built.

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

@@ -240,6 +240,25 @@ lead prepares a `/clear` as the mesh's instruction "prepare before clear" says:
 feature's phase, its branches and heads, the context files' paths, the agents' ids, the wait list and the
 next action; then the prompt the operator pastes. The context files make the feature resumable after a clear.
 
+## The design's state is written back
+
+Other sessions know what is built only from the design's frontmatter and the issue tracker; what the lead
+knows and does not write back, nobody else knows. A design merged as one release with three of its tasks
+left, its frontmatter still saying `designed`, read to another session as not built, and a second design
+was started beside it (issue 1009, 2026-10-17). So the lead writes the design's state back at each of these
+moments, the same hour, an hq change going through [playbook 08](08-small-fixes.md):
+
+- **The first step starts:** the design's `status: in-progress` ([playbook 04](04-build-handoff.md) step 7),
+  if it is not already.
+- **A step's delivery plan is done:** its issues are resolved (phase 4), and the design's milestone entry says
+  it is delivered, with the date.
+- **The building pauses with work left** (another design takes its turn, a hand-over, the session's end): the
+  design stays `in-progress`, and each issue left gets a note with `issue-tracker.note` saying what it waits
+  for and what comes after it ("built after design N is delivered, before design M"). The first issue of
+  a design that waits its turn gets the same note.
+- **The last milestone is delivered:** [playbook 02](02-graduation.md), "When something ships": the as-is is
+  written and the design says `implemented`.
+
 ## Issues that stop
 
 An issue stays in `fixing` only while an agent works on it. A step that stops, for a wait past its bound, a
@@ -254,6 +273,9 @@ issues in `fixing` that nobody works on reads to the operator as stuck work.
   phase 1, is the failure this playbook prevents.
 - A context file exists per touched repository under `.work/<slug>/` while the feature runs.
 - After a feature's delivery, `git branch -r | grep feat/<slug>` and `git worktree list` return nothing for it.
+- A design whose milestone issues are partly resolved says `in-progress`, and one whose issues are all
+  resolved and delivered says `implemented`: read its Milestones section against `issue-tracker.get` for each
+  issue. A design that says `designed` with a resolved milestone issue is a state not written back.
 - The milestone issues in `fixing` (`issue-tracker.list`) belong to one design at most: milestone issues
   of two designs in `fixing` at once is the failure of "one design is built at a time".
 - More than one open pull request in a repository that share no feature name, or a feature step whose issues