routing: default to transcribe, not the first preset

When no [routing] default is configured, default_preset fell back to
workflows[0]. If that was an LLM rewrite (e.g. "Improve text"), every
wakeword/voice command without a matching keyword was sent to the language
model — repeatedly failing with HTTP 502 when the LLM backend was down.

default_preset now prefers a transcribe-mode preset for the no-keyword
fallback, so the default action is plain transcription. Adds tests.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

linux/CHANGELOG.md

@@ -9,6 +9,13 @@ The version is defined in [`blitztext/__init__.py`](blitztext/__init__.py).
 
 ## [Unreleased]
 
+### Fixed
+- **Voice-routing default went to a rewrite**: when no `[routing] default` preset
+  is set, the no-keyword fallback used the *first* preset — which, if that happened
+  to be an LLM rewrite (e.g. "Improve text"), sent every unrouted wakeword command
+  to the language model (and failed when the LLM was down). The fallback now
+  prefers a `transcribe` preset, so the default action is plain transcription.
+
 ## [1.3.0] - 2026-06-07
 
 ### Added

linux/blitztext/config.py

@@ -110,7 +110,15 @@ class Config:
 
     @property
     def default_preset(self) -> "Workflow | None":
-        return self.preset_by_name(self.routing_default) or (self.workflows[0] if self.workflows else None)
+        named = self.preset_by_name(self.routing_default)
+        if named:
+            return named
+        if not self.workflows:
+            return None
+        # No explicit default configured: prefer a plain transcribe preset over
+        # whatever happens to be first, so the no-keyword fallback never silently
+        # routes to an LLM rewrite.
+        return next((w for w in self.workflows if w.mode == "transcribe"), self.workflows[0])
 
     @property
     def all_keywords(self) -> list[str]:

linux/tests/test_config.py

@@ -68,3 +68,26 @@ def test_properties():
     ]
     assert cfg.preset_by_name("WF2").name == "WF2"
     assert cfg.preset_by_name("NonExistent") is None
+
+
+def test_default_preset_prefers_transcribe_when_unset():
+    """With no routing default, fall back to a transcribe preset, not whatever
+    happens to be first (which could be an LLM rewrite)."""
+    cfg = Config()
+    cfg.routing_default = ""
+    cfg.workflows = [
+        Workflow(name="Improve text", hotkey="", mode="rewrite"),
+        Workflow(name="Transcribe", hotkey="", mode="transcribe"),
+    ]
+    dp = cfg.default_preset
+    assert dp is not None and dp.mode == "transcribe" and dp.name == "Transcribe"
+
+
+def test_default_preset_honours_explicit_name():
+    cfg = Config()
+    cfg.workflows = [
+        Workflow(name="Improve text", hotkey="", mode="rewrite"),
+        Workflow(name="Transcribe", hotkey="", mode="transcribe"),
+    ]
+    cfg.routing_default = "Improve text"
+    assert cfg.default_preset.name == "Improve text"