feat(reuse): recording gets a seam — the prior-art hook asks for create_snippet when duplication is proven and unrecorded (#2664)

Zero snippets were ever recorded outside sessions already thinking about
snippets: the read side had a real seam (the PreToolUse hook) and the record
side had a trailing clause of a floor bullet. The trigger moment — 'I just
wrote the second copy' — is mid-Write/Edit, so the nudge now rides the same
hook: when the local arm proves the definition exists elsewhere in the repo
AND Scribe returned no record of it, the context block asks for
create_snippet. Both gates or silence, so a brand-new helper and an
already-recorded one stay nudge-free.

Floor bullet promoted to name the trigger moments (extract, hoist, second
copy); guarded by test the same way the Systems reflex is. Plugin 0.1.29 so
the cache picks up the hook (#2209).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_write_path_trigger.py

@@ -789,3 +789,53 @@ def test_plugin_version_bumped_with_the_hook():
     manifest = json.loads((PLUGIN / ".claude-plugin" / "plugin.json").read_text())
     version = tuple(int(p) for p in manifest["version"].split("."))
     assert version >= (0, 1, 18)
+
+
+def test_hook_nudges_recording_when_copies_exist_but_nothing_is_recorded(tmp_path):
+    """#2664: the local arm proves duplication; when Scribe has no record of it,
+    the same context block must ask for create_snippet — the one moment the
+    recording nudge is earned rather than noise. An unreachable server counts
+    as "nothing recorded": the local finding needed no server, and the nudge
+    fails open with it (here: a refused connection stands in for the instance)."""
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    subprocess.run(["git", "init", "-q"], cwd=repo, check=True)
+    (repo / "a.py").write_text("def debounce(fn):\n    return fn\n")
+    # git grep searches the index, so the existing copy must be staged.
+    subprocess.run(["git", "add", "."], cwd=repo, check=True)
+    out = subprocess.run(
+        ["bash", str(HOOK)],
+        input=json.dumps({
+            "session_id": "s-nudge", "cwd": str(repo), "tool_name": "Write",
+            "tool_input": {"file_path": str(repo / "b.py"),
+                           "content": "def debounce(fn):\n    return fn\n"},
+        }),
+        capture_output=True, text=True,
+        env={"PATH": "/usr/bin:/bin", "SCRIBE_URL": "http://127.0.0.1:9",
+             "SCRIBE_TOKEN": "t"},
+    )
+    assert out.returncode == 0
+    ctx = json.loads(out.stdout)["hookSpecificOutput"]["additionalContext"]
+    assert "already defined" in ctx          # the duplication finding
+    assert "create_snippet" in ctx           # the recording ask riding it
+
+
+def test_hook_stays_quiet_about_recording_when_nothing_is_duplicated(tmp_path):
+    """A brand-new helper with no other copies earns no nudge — a reflex that
+    fires on every Write is one sessions learn to skip."""
+    repo = tmp_path / "repo"
+    repo.mkdir()
+    subprocess.run(["git", "init", "-q"], cwd=repo, check=True)
+    out = subprocess.run(
+        ["bash", str(HOOK)],
+        input=json.dumps({
+            "session_id": "s-quiet", "cwd": str(repo), "tool_name": "Write",
+            "tool_input": {"file_path": str(repo / "b.py"),
+                           "content": "def debounce(fn):\n    return fn\n"},
+        }),
+        capture_output=True, text=True,
+        env={"PATH": "/usr/bin:/bin", "SCRIBE_URL": "http://127.0.0.1:9",
+             "SCRIBE_TOKEN": "t"},
+    )
+    assert out.returncode == 0
+    assert "create_snippet" not in out.stdout