diff --git a/.claude/memory/MEMORY.md b/.claude/memory/MEMORY.md
index 1a3bf89..5fc2e07 100644
--- a/.claude/memory/MEMORY.md
+++ b/.claude/memory/MEMORY.md
@@ -2,3 +2,4 @@
 - [No nohup with pueue](feedback_no_nohup_with_pueue.md) — run `pueue follow|wait` directly as the bg task; nohup&  orphans it from the harness.
 - [Burn down task list](feedback_burn_down_task_list.md) — when many asks are queued, do them all; don't stop to ask which first.
 - [Workshop paper goal](project_workshop_paper_goal.md) — current phase is ablations+seeds for a workshop paper; artifact tracker A1-A7 lives in docs/spec/20260602_writeup_spec.md.
+- [Bash-tool shell gotchas](bash-tool-shell-gotchas.md) — noclobber ON + pi --mode json gives 0 bytes; use panel_direct.py / `>|` (generic box/env note, not repo-specific).
diff --git a/.claude/memory/bash-tool-shell-gotchas.md b/.claude/memory/bash-tool-shell-gotchas.md
new file mode 100644
index 0000000..13d1fd4
--- /dev/null
+++ b/.claude/memory/bash-tool-shell-gotchas.md
@@ -0,0 +1,33 @@
+---
+name: bash-tool-shell-gotchas
+description: Bash-tool zsh has noclobber ON and pi --mode json gives 0 bytes (non-tty); workarounds
+metadata: 
+  node_type: memory
+  type: feedback
+  originSessionId: ba4a4349-3947-4bfe-87fc-2d6e99001352
+---
+
+The Bash tool runs a zsh where `noclobber` is ON, and it is NOT set in any user rc
+file (`~/.zshrc`, `~/.zshenv`, etc. — grep finds nothing). So the harness/wrapper
+sets it; editing `~/.zshrc` does NOT turn it off. Symptom: `cmd > existing_file`
+fails with `file exists: <path>` and writes 0 bytes.
+
+Two recurring consequences and fixes:
+
+1. **`pi --mode json` writes to the tty, not stdout.** In this non-tty shell,
+   `pi ... | extractor` or `pi ... > file` yields 0 bytes (silently). Fix: skip pi,
+   hit OpenRouter HTTP directly — see `~/.claude/skills/external-review/panel_direct.py`
+   (stdlib-only, reads key from /root/.env). This is the robust path for the
+   external-review comprehension panel and external-panel Q&A.
+
+2. **noclobber refuses `>` onto existing files.** Use `>|` to force-overwrite, or
+   `rm -f` first, or have the program write the file itself (Python `Path.write_text`,
+   `tee` both work; `>` redirect does not).
+
+**Why:** wasted ~an hour chasing 0-byte panel output that looked like an auth/model
+problem but was noclobber + pi-tty. **How to apply:** when a `>` redirect or a piped
+CLI returns 0 bytes, suspect these two before debugging the tool itself.
+
+Also: batching many Bash calls in one message causes cascade-cancellation — if the
+first errors (e.g. the noclobber test exits 2), the rest are all cancelled. Run
+diagnostics sequentially. See [[projected-grpo-rebuild-from-pseudocode]].