Add startup bloat check for mutation build dirs

Record the tmp/acceptance and target/mutation-workers bloat that made
mutate4javascript worker copies many GB and mutation runs appear to hang.
Add a startup check that flags any of these dirs over 100MB so they are
cleaned before a mutation run.

By architect.

docs/architect-process-notes.md

@@ -49,6 +49,19 @@ distinct from per-task verification results, which live in
   to keep the worker copies tiny. This cut a notifications-query mutation run
   from 20+ minutes to ~2 minutes.
 
+- **Which directories bloat and how to keep them clean.** The two directories
+  that grow without bound are `<component>/tmp/acceptance` (LevelDB dirs from
+  acceptance runs, up to ~1.5G) and `<component>/target/mutation-workers`
+  (per-run worker copies, up to ~14G). Both are gitignored build artifacts.
+  Clean them before any mutation run:
+  ```bash
+  rm -rf psf-memo-db/tmp/acceptance psf-memo-db/target/mutation-workers \
+         psf-memo-client/tmp/acceptance psf-memo-client/target/mutation-workers
+  ```
+  `architect-startup.sh` now checks these and reports them as `[FAIL]` when
+  they exceed a size threshold, so a bloated dir is caught before it slows a
+  mutation run.
+
 - **`memo-db.js` (client HTTP adapter) is excluded from mutation testing.** It
   uses ESM + a directory import (`../config`) that is only resolvable via
   react-scripts/webpack, so it cannot be loaded under plain `node --test`. Its

docs/architect-startup.md

@@ -48,6 +48,18 @@ Parse survivors with a small python one-liner over `d['results']` (filter
   `--workers 8` and `--status-interval` so progress is visible.
 - Run verification sequentially (never concurrent with acceptance generation).
 
+## Keep build dirs clean (mutation speed)
+`mutate4javascript` copies the whole project (including `tmp/`) into each worker.
+Stale `tmp/acceptance` (LevelDB dirs) and `target/mutation-workers` can bloat to
+~1.5G and ~14G, making the worker copy alone many GB and mutation runs appear to
+hang. `architect-startup.sh` now flags any of these over 100MB as `[FAIL]`.
+Clean them before any mutation run:
+```bash
+rm -rf psf-memo-db/tmp/acceptance psf-memo-db/target/mutation-workers \
+       psf-memo-client/tmp/acceptance psf-memo-client/target/mutation-workers
+```
+This cut a notifications-query mutation run from 20+ minutes to ~2 minutes.
+
 ## Refactorer forwards your own review commit back
 After you send a `priority: 00` review commit to coder+refactorer, the refactorer
 merges and forwards that SAME commit back to you. It is a no-op ("Already up to