Block handoffs from a dirty working tree

Unrelated tracked changes could ride along with a handoff. Refuse to send when
git status --porcelain is non-empty, list the offending files, and keep the
draft so it can be fixed and resent. SWARMFORGE_ALLOW_DIRTY=1 overrides.

By specifier.

specifier-prompt.md

@@ -459,13 +459,14 @@ At the end of each session, update this file:
 - Note the current `master` HEAD commit.
 - State the next feature to work on.
 
-Current `master` HEAD: `c8ceb82` (merged architect's thread-query-bounds job —
-`GET /posts/:txid/thread` now counts likes only for the thread's txids via
-`countLikesForTxids` and prefix-scans `postChildren` per parent through a new
-`PostQuery.listChildTxids` seam, so its work is proportional to the thread
-rather than the database. Spec:
-`psf-memo-db/specs/thread-query-performance.feature`. Verified psf-memo-db unit
-(357) + property (44) + acceptance (all 11 suites) + lint all passing).
+Current `master` HEAD: `a5f8967` (thread-query-bounds merged at `c8ceb82`, then
+a process-improvement pass on this branch: the architect now always notifies
+the specifier; acceptance LevelDB temp dirs are cleaned up; the handoff daemon
+is self-healing; APS is single-sourced at `tmp/aps`; acceptance generation is
+incremental; `verify.sh` emits a machine-readable verification record;
+`mutate-file.sh` guards differential under-selection; and `clean-builds.sh`
+keeps mutation worker copies small. Run `swarmforge/scripts/state.sh` to refresh
+these HEAD lines.)
 Next action: **TBD** — current direction is front-end improvements to
 `psf-memo-client` (UI/UX polish, accessibility, performance, responsiveness,
 state handling, error surfacing). See `specs/feature-backlog.md`.

swarmforge/scripts/swarm_handoff.bb

@@ -302,6 +302,20 @@
     (fs/move tmp-file outbox-file)
     outbox-file))
 
+(defn dirty-files []
+  (->> (:out (command "." "git" "status" "--porcelain"))
+       str/split-lines
+       (remove str/blank?)))
+
+(defn guard-clean-tree! []
+  (let [dirty (dirty-files)]
+    (when (and (seq dirty) (not (System/getenv "SWARMFORGE_ALLOW_DIRTY")))
+      (binding [*out* *err*]
+        (println "HANDOFF BLOCKED: working tree has uncommitted changes.")
+        (doseq [line dirty] (println "  " line))
+        (println "Commit or stash them, or set SWARMFORGE_ALLOW_DIRTY=1 to send anyway."))
+      (System/exit 3))))
+
 (defn error-report [draft errors]
   (binding [*out* *err*]
     (println "HANDOFF INVALID:" (str draft))
@@ -328,6 +342,7 @@
         (when (seq all-errors)
           (error-report draft all-errors)
           (System/exit 2))
+        (guard-clean-tree!)
         (let [outbox-file (write-handoff! {:headers headers
                                            :recipients (:recipients validation)
                                            :canonical-commit (:canonical-commit validation)