memory: record context-priming discard-cut abandonment (chatterbox-fast)

persistent-memory.md

@@ -324,6 +324,22 @@ _25 older entries archived to archival-memory.md._
 
 ## Tried and abandoned
 
+- `[2026-06-02]` **Context-priming at chunk joins (chatterbox-fast §1.6) —
+  ABANDONED (discard-cut leaks the prefix).** To give a chunk backward prosodic
+  context, prepend the prior sentence, generate `prefix+content` together, then
+  discard the prefix audio. Built + opt-in shipped (commit d707439), live-A/B'd,
+  reverted (090e70a). The kill: `generate()` returns one finished waveform with
+  NO marker for where the prefix ends, and the model renders the same prefix with
+  different timing solo vs followed-by-content — so locating the cut (generate
+  prefix solo → measure duration → snap to nearest energy-min pause within ±0.4s)
+  is a guess that left a whole clause of prefix in the output ("...without a trace
+  of sarcasm," spoken twice; operator caught it). A reliable cut needs token-level
+  boundaries (= the abandoned native-streaming arc) or per-chunk ASR/forced-
+  alignment (heavy, imperfect, eats the latency budget). → Coherence loss at joins
+  stays an ACCEPTED limitation; cold adaptive-chunk streaming judged "really good".
+  Scheduler-side work that DID land + survive: affordability-gated priming math
+  (a 2nd pass can't starve the buffer) — sound, but moot without a working cut.
+
 - `[2026-06-02]` **Native frame-level streaming on Chatterbox-TURBO — ABANDONED
   (turbo isn't built for streaming).** Long R&D arc; record so it's not
   re-derived. (1) The model's flow is CosyVoice2-derived but `S3GenStreamer` is