practice: ONE send lane — the register is read from the text

Owner round 2 (2026-10-05), Slice H: the Nudge/Commit two-lane buttons
are gone. One Send; Enter sends, Shift+Enter is a newline. Whether a
submission claims an answer is apparent from the thinking itself — the
agent reads it (hint ladder for traces, moves+verdict for claims).

- The thinking input loses the commit field end-to-end: ChatInput,
  parseChatInput, newThinkingMessage (details and the model-facing label
  both collapse to the single 'Your thinking'), the optimistic marker.
- Legacy records' commit flags are deliberately unread.
- Doctrine: the two labeled channels become one read instruction; 'answer
  commits' section retitled 'Claimed answers' — a claim is not a
  progress signal.
- ThinkingCard: one label, collapsed arrival (the unified row).
- The dock placeholder no longer explains lanes that no longer exist.

src/agent/prompts/practice/00-base.md

@@ -23,10 +23,10 @@ He has to be able to trust you completely; one confidently-delivered hallucinati
 
 Two tools, and everything else is conversation. The mechanics only — the method (when to pose, what to pose, how to respond) is the doctrine's.
 
-**`problem`** — poses one problem. The statement field is what the learner sees (markdown and LaTeX render); the modelSolution is your private commitment, hidden from the learner until you conclude. The call ends the turn. The learner then works in a thinking field; their submissions arrive back as labeled messages:
+**`problem`** — poses one problem. The statement field is what the learner sees (markdown and LaTeX render); the modelSolution is your private commitment, hidden from the learner until you conclude. The call ends the turn. The learner then works in a thinking field; each submission arrives back as a *Your thinking* message. Whether it claims an answer is IN THE TEXT, not declared anywhere — read it:
 
-- *Thinking trace (working, not committed):* they are mid-work and asking for a nudge. This is a hint request — the hint ladder applies, one rung per request. A trace may span several of these.
-- *Committed answer:* they claim an answer. Extract the moves, deliver the verdict. Remember: a commit is not a progress signal.
+- Working trace (mid-work, stuck, or asking for a nudge): the hint ladder applies, one rung per request. A trace may span several submissions.
+- A claimed answer: extract the moves, deliver the verdict. A claim is not a progress signal.
 
 Only one problem may be active at a time — the tool rejects a pose while one is live. Conclude before posing the next.