Draw a model's thinking, and what a reply cost to produce

A llama.cpp session's `reasoning_content` becomes `Event::Thinking` deltas
closed by an `Event::ThinkingDone` carrying the span the driver measured, and
the phone draws it as a card of its own: "Thinking" with the spinner a running
command has, then "Thought for 12.4s". Deliberately not a tool call, so a run
of calls cannot collapse the reasoning into "Called 6 tools"; the reasoning is
also kept out of the next prompt, which `conversation` already ignored.

`UsageDelta` gains `tokensPerSecond`, the provider's own figure or nothing --
llama.cpp reports `timings.predicted_per_second` and the coding CLIs report no
such thing -- and a finished reply carries a small line under it saying when it
was sent and, where there is one, how fast it came out: "3:00 PM · 149 tok/s".

The compact usage bar drops the provider's name for the window and puts its
length after the time left instead: "42% · 3h 20m left / 5h".

Three things that had to come with it: the transcript coalesces runs of
thinking deltas as it does reply deltas, so one block is one row of a page
rather than a page of its own; `joinPages` welds a block cut by a page boundary
(`healSplitThinking`), since the half with no ending spun for ever; and
`UsageDelta` now reaches the fold, which is what carries the rate to the reply.

Verified on the emulator against a real Qwen3-0.6B session and the echo rig's
new `/think [seconds]`: the spinner while it runs, "Thought for 1.4s" and
"2:54 PM · 149 tok/s" after, the reasoning on tapping the card, and the usage
bar reading "42% · 3h 19m left / 5h".

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

AGENTS.md

@@ -62,6 +62,14 @@ Module-by-module intent is in PLAN.md's "Backend layout".
   MTP draft head is a 50% speed-up or a 33% loss; and `--spec-type draft-mtp`
   is conditional on the file actually having a head, because asking for one
   that is not there makes `llama-server` **exit**.
+  **A llama session's thinking is drawn** (2026-09-19): `reasoning_content`
+  becomes `Event::Thinking` deltas closed by an `Event::ThinkingDone` carrying
+  the span the *driver* measured, and the phone draws a card that spins while
+  the block is open and says "Thought for 12.4s" once it is not. The reasoning
+  is deliberately not part of the next prompt (`conversation` ignores it), and
+  `timings.predicted_per_second` off the same stream becomes `UsageDelta`'s
+  `tokensPerSecond`, which is the "149 tok/s" under a finished reply — nothing
+  else here measures one, so every other driver sends `None`.
   **Every one of those is a default rather than a constant** (2026-09-19):
   `DriverKind::params` declares what a provider takes — key, label, shape,
   and whether a change waits for a restart — and the phone renders whatever