the correction, written down (V-630)

docs/plans/22-correcting-a-turn.md

@@ -0,0 +1,60 @@
+# Correcting a turn
+
+Last verified: 06-08-2026 @ 0d5bd0a
+
+V-630, under V-628. Reads with `21-persisting-the-routing-trace.md`.
+
+## Why a gesture and not a form
+
+The routing trace (V-629) stores every turn. Almost all of them routed correctly, so
+almost all of them teach nothing. A correction is the only high-value supervised signal
+the box produces. It is also the only one that costs the owner something to give.
+
+So the design constraint is the cost, not the schema. One gesture beside the reply. No
+form, no separate page, no passkey tap.
+
+## Two things to capture, and only one of them is required
+
+A correction has two halves.
+
+- This turn was wrong.
+- It should have been *this*.
+
+The second is worth much more. It names which boundary moved, and it is what a fitted
+head trains against. But requiring it would price out the first, and a turn marked wrong
+with no target is still a usable negative. So the target is optional. The trace carries
+`wrong` when he did not say.
+
+The target is one of the seven intents and never free text. V-632 fits prototypes from
+that table. An unroutable label would enter it, and a label nothing can score is worse
+than no label.
+
+## Where the label lives
+
+`routing_labels`, migration #24, keyed unique on the utterance. A second correction of
+the same sentence replaces the first, because his later answer is the one he meant.
+
+It is a separate table from `routing_traces` on purpose. The transcript expires after 14
+days. The label does not. A label is a sentence, an intent and an encoder id. That is not
+a transcript, and the reversal in doc 21 rests on the distinction.
+
+`was` is stored beside `should_be`. The pair is what names the confusion. A label with no
+`was` cannot say which boundary moved.
+
+## Reach
+
+`CorrectTurn(traceID, shouldBe)` takes no browser and no session. The trace id rides back
+on `ipc.ChatReply` through the same context sink the query source badge uses. Nothing in
+the seam assumes the web.
+
+Only `/chat` offers the gesture today. That is a gap, named rather than closed. If the web
+is the only place to correct a turn, the sample skews to whatever the owner types at. Voice
+is where the hard cases are. Telegram has the obvious shape, an inline keyboard on the
+reply. Voice does not. Inventing a spoken correction grammar would put a recogniser in
+front of the one signal that exists to fix recognisers. Both are follow-on work.
+
+## What is not decided
+
+Whether the owner ever wants to see the labels he gave. Nothing reads the table outward
+yet. `/trace` shows the ring, which is 25 turns and in memory, and a labels view is a
+different page with a different question.