Give a local model room to think without spending the answer on it

llama.cpp counts the thinking towards max_tokens along with the answer it
precedes, and the local ceiling was sized for the answer alone. Turning
Thinking up therefore came out of the reply rather than being added to
it, and on a short dictation the 512 floor is the whole budget, so the
model spent it in the think block and came back with nothing to paste.

Each rung of the ladder now carries its own budget, doubling from 256 at
"minimal" to 8192 at "maximum", added on top of the answer's share
rather than taken out of it. The rungs are small because cleanup is
punctuation and locally every one of these tokens is also a second of
somebody standing in front of the screen. "Off" keeps the old tight
ceiling untouched, and an empty setting is given a middling amount,
since a template that can think thinks by default and there is no way to
ask which kind of model this is.

The ceiling is also held under what the server was started with. Above
the context it is not a ceiling at all: the runaway it exists to stop
would run to the end of the context instead, which on CPU is minutes of
waiting. The prompt keeps its share at two characters to the token,
which is under any tokeniser's rate for natural language and so reserves
too much rather than promising room that is not there.

Separately, a reply cut off at somebody's ceiling was returned as if it
were whole. Half a sentence looks like a cleaned-up transcript and is
not one, so finish_reason is now read in both cleanup and chat. The
callers already keep the transcript they started with, which is the
better of the two. This one is not local-only: a hosted provider
stopping at its own output limit was silently pasted the same way.

tests/test_api.py

@@ -463,6 +463,29 @@ class Cleanup(DikteTest):
         with fake_urlopen(chat_reply("   ")), self.assertRaises(api.ApiError):
             api.cleanup("hello", "k", "m", "p")
 
+    def test_a_reply_cut_off_at_a_ceiling_is_refused_rather_than_pasted(self):
+        # Half a sentence looks like a cleaned-up transcript and is not one. The
+        # caller keeps what it was given, which is the whole dictation.
+        reply = {"choices": [{"message": {"content": "Hello, and then the"},
+                              "finish_reason": "length"}]}
+        with fake_urlopen(reply), self.assertRaises(api.ApiError) as caught:
+            api.cleanup("hello", "k", "m", "p")
+        self.assertIn("cut off", str(caught.exception))
+
+    def test_a_reply_that_stopped_on_its_own_is_kept(self):
+        reply = {"choices": [{"message": {"content": "Hello."},
+                              "finish_reason": "stop"}]}
+        with fake_urlopen(reply):
+            self.assertEqual(api.cleanup("hello", "k", "m", "p"), "Hello.")
+
+    def test_all_thinking_is_named_before_the_ceiling_it_was_cut_at(self):
+        """Both are true at once, and only one of them says what to change."""
+        reply = {"choices": [{"message": {"content": "", "reasoning": "hmm"},
+                              "finish_reason": "length"}]}
+        with fake_urlopen(reply), self.assertRaises(api.ApiError) as caught:
+            api.cleanup("hello", "k", "m", "p")
+        self.assertIn("Thinking", str(caught.exception))
+
     def test_a_rate_limit_is_explained(self):
         with fake_urlopen(http_error(429)), \
                 self.assertRaises(api.ApiError) as caught:
@@ -471,6 +494,14 @@ class Cleanup(DikteTest):
 
 
 class Chat(DikteTest):
+    def test_an_answer_cut_off_at_a_ceiling_is_refused_rather_than_pasted(self):
+        # Half an answer reads like a whole one once it is on the screen.
+        reply = {"choices": [{"message": {"content": "Booked it for the"},
+                              "finish_reason": "length"}]}
+        with fake_urlopen(reply), self.assertRaises(api.ApiError) as caught:
+            api.chat([{"role": "user", "content": "book it"}], "k", "m", "p")
+        self.assertIn("cut off", str(caught.exception))
+
     def test_the_history_is_sent_after_the_system_prompt(self):
         history = [{"role": "user", "content": "book it"},
                    {"role": "assistant", "content": "done"}]
@@ -616,11 +647,13 @@ if __name__ == "__main__":
 class FakeServer:
     """A ggml.Server as far as api.py is concerned."""
 
-    def __init__(self, url="http://127.0.0.1:9999/v1", fails="", log=""):
+    def __init__(self, url="http://127.0.0.1:9999/v1", fails="", log="",
+                 context=8192):
         self.url = url
         self.fails = fails
         self.log = log
         self.starts = 0
+        self.context = context
 
     def serve(self):
         self.starts += 1
@@ -631,6 +664,9 @@ class FakeServer:
     def error(self):
         return self.log
 
+    def settings(self):
+        return {"context": self.context}
+
 
 LOCAL = api.Target("local", "Local whisper", "", "", "ggml-base.bin")