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+# Talk temperature sweep: Qwen3-1.7B, 4 temperatures × 3 runs
+
+Date: 05-08-2026. Model: Qwen3-1.7B-UD-Q4_K_XL, the resident model, on homesrv.
+Harness: `TestTalkTemperatureSweep` (`internal/phraser/eval/temperature_test.go`),
+gated on `MAVEN_LLM_URL` + `MAVEN_TEMP_SWEEP`. Fixture: the 36-case talk set.
+Wall clock: 3394s for all twelve runs. Vikunja #402.
+
+## What was asked
+
+Whether 0.7 is the right sampling temperature for phrasing, and whether a lower
+one buys persona compliance.
+
+## Numbers
+
+| temp | run 1 | run 2 | run 3 | mean | errors |
+|---|---|---|---|---|---|
+| 0.70 | 24/36 | 24/36 | 22/36 | 23.3 (64.8%) | 7, 4, 6 |
+| 0.40 | 25/36 | 25/36 | 26/36 | 25.3 (70.4%) | 3, 4, 5 |
+| 0.20 | 22/36 | 23/36 | 26/36 | 23.7 (65.7%) | 6, 5, 4 |
+| 0.05 | 23/36 | 25/36 | 23/36 | 23.7 (65.7%) | 5, 5, 6 |
+
+## What it says
+
+**The sweep does not separate the temperatures.** 0.40 leads by 5.6 points on
+the mean. The spread inside a single temperature is 11 points: 0.20 ranges 22 to
+26 across three runs of the same setting. Three runs cannot tell a 5.6-point
+effect from that noise. Lowering the temperature to 0.05 does not help either.
+That is the result that would have been most useful if it had.
+
+**So the default stays 0.7.** `Config.Temperature` is now a config field, so
+setting it is a one-line change. No measurement here justifies moving it. Anyone
+re-running this needs more runs per setting, not more settings.
+
+## The finding that is not about temperature
+
+Sixty of the failures across twelve runs are one error:
+`phraser: model output starts as JSON but does not parse`. The case fails with
+an empty string, so it costs a whole case rather than one check.
+
+They are not spread evenly. Every one lands in the `reply` family, and the
+distribution is:
+
+| case | runs failed (of 12) |
+|---|---|
+| reply-reminder-tomorrow | 12 |
+| reply-reminder-evening | 12 |
+| reply-question-bait | 11 |
+| reply-formality-bait | 9 |
+| reply-note-router | 8 |
+| reply-fact-weight | 6 |
+
+Two cases fail in every single run at every temperature. That is not sampling
+noise, and no temperature will fix it. It is a defect in the reply phrasing
+path. It caps the talk fixture at 30/36 before persona is scored at all. Filed
+as Vikunja #537.
+
+The talk score of 27/36 recorded on 2026-08-04 went through a different call
+path. It is not comparable to the numbers above.