chore(memory): BDR-094 LRN-159 BLK-021, journal + TODO 2026-09-22

.claude/memory/blockers.md

@@ -242,3 +242,9 @@ rules:
 - **Status**: resolved (A: ext hooks only terminals born after activation → install ext THEN start/re-attach session; B: Code app volume 0 in Windows mixer).
 - **Lesson**: two independent client faults presented as one symptom ("nothing works"). Splitting probe = run signal in FRESH terminal + play VS Code's own sound preview. Preview bypasses terminal/BEL/hook/dtach/ext → isolates renderer audio in one step. Do that FIRST next time, before any server-side archaeology.
 - **Reference**: [[BLK-019]] bell-only variant (resolved differently — setting alone insufficient here), [[LRN-145]] terminalSequence-not-/dev/tty pattern. Silent-degradation class [[LRN-047]].
+
+## BLK-021 — Bash tool dead mid-session ("every command exits 1"): /tmp usrquota blown by a dead session's probe HOMEs — 2026-09-22
+- **Friction**: previous session on `feature/21st-cli-migration` lost its shell before tests + commit: every Bash call, `echo` included, returned 1. Its harness file `imptest2/step8d-test.sh` landed as 0 bytes.
+- **Real cause** (strong evidence, not reproduced on purpose): `/tmp` = tmpfs 7.4 GB mounted `usrquota`; `/tmp/claude-1000/-home-bchanot-Documents-claude/fefd277c-…/scratchpad` holds 5.9 GB of sandbox HOMEs (`pinprobe/` 2.1 GB, `pinrc/` 1.6 GB, `imp1 impg imptest sbx1 sbx2 v3.2.0 v3.6.1 v4.0.5 …`) from the impeccable pin probes. `dd` 40 MB to `/tmp/claude-1000` → "Disk quota exceeded" (EDQUOT) while `df` still shows 1.6 GB avail. Same write to `~/.cache` OK. Bash tool + `mktemp` + heredocs live in /tmp → all die together. This session: first impeccable probe failed with `Quota exceeded (os error 122)` on the installer's `/tmp/impeccable-update-*` staging, same cause.
+- **Solution**: this round ran everything with `TMPDIR=~/.cache/imp-probe/tmp` (probe, harness, `make test`). Durable fix = delete the dead session's scratchpad: `rm -rf /tmp/claude-1000/-home-bchanot-Documents-claude/fefd277c-e143-4d51-b589-a566641079b5` (agent's `rm -rf` on /tmp denied by the classifier → user action). Rule for probes: sandbox HOMEs that pull npm/node payloads go under `~/.cache/<probe>/`, never the /tmp scratchpad, and get removed at the end of the session.
+- **Status**: open until the user frees /tmp. Links [[BDR-094]], [[LRN-159]].