From 2292098784c766ccb80f6d23bac34617f922df22 Mon Sep 17 00:00:00 2001
From: marksverdhei <marksverd@gmail.com>
Date: Sat, 27 Jun 2026 19:31:56 +0200
Subject: [PATCH] fix(hat): don't rename to a stem-less dotfile on a degenerate
 model answer
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

`sanitize_name` appended the original extension unconditionally, so an empty
or unusable answer (e.g. a reasoning model that spent its whole budget inside
<think> and emitted no name, or punctuation like "." / "/") produced a
stem-less name like ".jpg". That's non-empty, so it slips past the caller's
`-z "$suggested"` guard and renames the file to a hidden, stem-less file —
effectively losing it.

Strip leftover dots/dashes from the stem and, if nothing remains, emit no name
so the empty-guard rejects the rename and reports "(no suggestion)".

Adds 3 regression tests (empty / think-only / punctuation-only → no name).
All 80 bats tests pass.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 hat     |  7 ++++++-
 test.sh | 20 ++++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/hat b/hat
index 020a5b8..33373d7 100755
--- a/hat
+++ b/hat
@@ -527,7 +527,12 @@ name = re.sub(r"-+", "-", name).strip("-")
 if preserve_ext == "true" and orig_ext:
     if "." in name:
         name = name.rsplit(".", 1)[0]
-    name = name + "." + orig_ext
+    name = name.strip("-.")
+    # An empty stem means the model gave nothing usable (e.g. a reasoning model
+    # that spent its budget inside <think> and emitted no answer). Emit no name
+    # so the caller's empty-guard rejects it, instead of renaming the file to a
+    # stem-less dotfile like ".jpg".
+    name = name + "." + orig_ext if name else ""
 print(name)
 SANITIZE
 }
diff --git a/test.sh b/test.sh
index 2f61b85..66bc502 100755
--- a/test.sh
+++ b/test.sh
@@ -126,6 +126,26 @@ teardown_file() {
   assert_output "second-name.txt"
 }
 
+# Regression: a degenerate model answer (empty / think-only / punctuation) must
+# NOT become a stem-less dotfile like ".jpg" — that slips past the caller's
+# empty-name guard and renames the file to a hidden, stem-less file. Emit
+# nothing so the rename is rejected.
+
+@test "sanitize: empty answer yields no name (not a dotfile)" {
+  run sanitize_name "" "true" "jpg"
+  assert_output ""
+}
+
+@test "sanitize: think-only answer yields no name" {
+  run sanitize_name "<think>spent my whole budget reasoning</think>" "true" "jpg"
+  assert_output ""
+}
+
+@test "sanitize: punctuation-only answer yields no name" {
+  run sanitize_name "." "true" "jpg"
+  assert_output ""
+}
+
 # ── Binary detection ─────────────────────────────────────────────────
 
 @test "binary: text file is not binary" {