"It still flickers sometimes" is not something a fix can be tested against,
so the first change is a counter. Drawing is the one place that knows both
what is on screen and what was built, so it asks: `covered()` compares the
rows in the viewport against the window and records how far short it fell
and which way. That turned a symptom into a number, and the number found
four separate causes -- three of which I would not have guessed, and one of
which I had already "fixed" twice.
- Opening a session recomputed the window before the scroll container had
measured anything. `maxValue` is zero then, which reads as the reader
being at the oldest end, so the window landed a whole transcript away
from where the session was about to open.
- A page of history recomputed it from a scroll position one layout out
of date -- stale by exactly the height of the page that had just
arrived. The reader's position is now carried across the change as a
row rather than as a pixel, and resolved through the row that *holds*
that seq, because a regroup can fold the row it named into another.
- The window was widened to cover the screen only when it was recomputed,
which was every two screens of movement. A fling covers a screen in a
frame or two, so it outran the window and arrived at rows that were
still spacers. Standing rows up a few per frame made that worse rather
than causing it: after a seed the built window is two screens wide and
grows two rows a frame. What is near the screen is now widened every
frame; only the outer bound is lazy.
- Both were measured in pixels, and a pixel budget cannot know how many
rows it covers until the rows have been measured -- which is never, on
the frame a session opens. The margins are now a number of screens *or*
a number of rows, whichever is larger.
The recompute moved to the transcript's placement, which is the one moment
both halves are current: the rows have just been measured and so has the
scroll container. Everywhere else it ran could be right about one and stale
about the other. It writes only when the answer changes, so a frame where
nothing moved costs one scan and no recomposition.
Two supporting fixes. `covered()` also repairs, so however the window goes
stale the damage is one frame rather than until the next scroll. And the
scroll position is now keyed per session -- `rememberScrollState()` is not
keyed, so a second session opened without leaving the screen inherited the
first one's offset and, worse for the window, its `maxValue`.
Verified on the emulator: flings up and down, three scroll-and-restore
cycles on a 92-row session and three reopens of a short one -- zero, where
before each reopen cost one to three. Placement stayed at 0.8ms.
Also here: crashes are recorded and travel out through the debug button, so
"it crashes opening that chat" arrives with a stack next time; the report
goes to the log as well as the clipboard, so a session driving the app over
adb can read it; and `trace-draw.sh` captures a labelled frame breakdown,
with a note that it must be run against the phone -- on this emulator two
thirds of a frame is `dequeueBuffer` and Compose's own draw is 0.40ms.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Three things, all of them the same shape: work done because something was
asked a question at the wrong moment.
The keyboard. The layout modifier passed `minHeight = viewportSize` down
to its child, so every frame of the IME animation changed the child's
constraints -- and changed constraints are exactly what defeats the
early-return in `MeasurePassDelegate.remeasure`. The whole transcript was
re-measured on the way up, measured on a Pixel 9 Pro XL as 250
measurements averaging 2.8ms with a 54.5ms worst. The minimum is applied
to what this node reports now, not to what it asks its child for, so the
child early-returns; the content is placed against the bottom to keep the
anchoring the minimum existed for. It only ever bites on a conversation
shorter than the screen, which was never the case paying for it.
The flicker. `retained` starts empty, so on the composition that
introduces the rows every one of them is outside the window, the whole
transcript collapses to a single spacer, and it draws blank for a frame.
Seeded now -- at the newest end on open, and around the anchor on a
restore. The restore case is the one that bites: `placed()` jumps the view
during placement, and a window recomputed there only schedules a
recomposition, so the destination would draw as spacer for a frame or two
after drawing ungates. Seeded by pixels rather than by a row count,
because a run of tool calls is eight rows and less than half a screen.
The block layers. Every paragraph of every reply had a layer, which was
right when whole rows were re-recording constantly and one row's display
list was 36,982px tall. Re-recording is rare now -- 65 whole rows in fifty
seconds of reading -- and a layer costs a layout node and a display list
held for the life of the row, against the node count the per-frame cost
scales with. They go to the message still arriving, which is the only one
whose drawing is invalidated often enough to want the granularity.
Verified on the emulator against the case none of this was written for: a
two-message conversation far shorter than the viewport still hangs from
the composer, with the keyboard both up (messages at y1756-1940, composer
2109) and down (936-1120 against 1289).
Mechanism for the block layers and the hole in the restore seeding both
from the ai-app-2-6d session; the layers are not re-positioned per frame
as I had it, they are baked into the row's display list.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Two things committed in 9052e5f and 94b1509 were never wired up. The row
count was tracked and nothing observed it, so the fix for the gap when
sending was inert; `standUpSome` and `growing` were written and nothing
called them, so the window still jumped in one step. Both are connected
now, which is what the last two commit messages already claimed.
The third thing is what the counters were pointing at all along. The
frame's draw phase sat at a flat 7.7ms -- p99 only 1.8x p50, so not
shaping, which is spiky -- while the transcript's own recording ran 43
times in 3638 frames and accounted for a fortieth of it. A stood-down row
drew nothing but was still a layout node, and the framework's per-frame
bookkeeping after a scroll walks live nodes rather than visible ones. So
the cost grew with the conversation instead of with the screen, which is
exactly the step the reader felt at each page loaded.
The rows outside the window are now two spacers rather than one per row,
which they can be because the window is a range: what is not in it is one
run before and one run after. Live nodes are bounded by the window now.
The gaps between collapsed rows are added into the spacer, because
`spacedBy` puts a gap between children and a run drawn as one child is
short by all of them -- which would not read as a spacing bug, it would
move everything under the reader.
Measure and place are timed separately now. The draw phase carries
Compose's measurement, so "draw is high while nothing is recorded" could
not say which half, and the two have different fixes.
Diagnosis from the ai-app-2-6d session: foundation already places scrolled
content with `placeRelativeWithLayer`, so the scroll is a layer transform
today and re-placing children was never the cost -- the node-count walk
is, and collapsing the runs is the experiment that settles it.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The counters now say which half is left. Re-recording is rare -- 157 row
display lists in a minute of scrolling, 407ms in total -- while the
frame's draw phase sits at 7.9ms. Since that phase also carries Compose's
own measurement, what is left is laying text out: shaping glyphs, on the
thread drawing the frame, and none of it timed by anything here.
The window moved in one step, so every step boundary shaped two screens
of markdown inside a single frame, a page landing did the same, and
opening a session did seventeen screens of it in one. It now walks
towards its target a couple of rows a frame. That does not make the work
cheaper and is not meant to: it stops it arriving together, which is the
difference between a frame that is late and a frame that is missed by
ten.
What is on screen is never amortised. The visible range goes up in the
frame it is needed whatever else is pending, and only the margin being
read *towards* is spread out -- so this cannot show anybody a gap, which
is the failure the last two changes in this area both had.
Diagnosis and the ordering from the ai-app-2-6d session, whose test this
follows: records small and draw high means shaping rather than recording.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Two faults from making the retained window lazy, both of them mine.
A screen of blank between the last message and the box it was typed in.
The window was recomputed when the view had moved far enough, and a
message arriving does not move the view -- so the new row fell outside
the window and stood in as a spacer of its guessed height. The version
number the check compares against is only bumped by the recompute it
guards, so asking before refreshing meant never noticing. It refreshes
first now, and the window also watches how many rows there are, because
a row arriving is the case it exists to catch and the one that does not
announce itself through the scroll position.
And the keyboard, which was the most expensive thing on the screen. The
visible height came from a `BoxWithConstraints` wrapped around the
transcript -- that is a `SubcomposeLayout`, and the IME animation changes
the visible height on every frame of its slide, so the entire transcript
was being subcomposed again for each of them. The same number read in
the layout phase, from the scroll container's own measurement, makes it a
relayout instead, and the rows keep the measurements they already have.
Checked on the emulator: the newest message sits against the composer
with the keyboard up, and there is no gap.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The same mistake as the draw-phase culling, moved into another phase.
Each row held a `derivedStateOf` over the scroll position to decide
whether it stayed built. That reads correctly and costs the same shape:
every one of those derived states is invalidated by every scroll frame
and has to be re-evaluated to learn whether its answer changed, so the
per-frame work grew with the number of loaded rows again -- this time
landing in the recomposition pass, which the platform reports as the
frame's animation phase. On a Pixel 9 Pro XL at 153 rows that was 11.6ms
at the median, against an 8.3ms frame, and it was the largest term left.
The window is now one range that every row reads, recomputed once a
frame from one observer. And recomputed lazily: every row reads it, so
every change to it disturbs all of them, which is affordable once every
couple of screens and is not affordable at row boundaries, where a fling
would cross one every few frames. The window is eight screens either
side and it moves in steps of two, so the margin absorbs the staleness.
Worth naming as a pattern, since this is the third time: a per-row
answer to a question about the scroll position is O(rows) per frame
wherever it is evaluated -- in draw, in a derived state, anywhere. The
question has one answer and it belongs in one place.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Scrolling up emptied the screen and only reopening the session brought
it back. The guess for an unmeasured row's height was re-derived from a
running average each time it was wanted, and that average moves as rows
are measured -- so the height a spacer had been *built* at stopped
matching the height the running totals were adding up, and the two drifted
apart. Once they differed by more than the retain window every row failed
the distance test at once, and a transcript of nothing but spacers has
nothing left to measure and so nothing to correct itself with.
Two changes, and the second is the one that matters. A guess is now made
once per row and kept, so it cannot drift from what was built with it.
And which rows stay built is decided as a *range* rather than by each row
testing itself: the row nearest the viewport is in that range by
construction, whatever the arithmetic says, so the worst a mistake here
can do is build too few rows or too many. A blank transcript is no longer
a state this can reach.
That is the shape worth keeping from the bug. Every row answering
independently meant one wrong number could stand all of them down
together, and the failure was silent, self-sustaining, and looked exactly
like the screen having nothing to show.
Checked by scrolling sixty swipes to the oldest loaded end and back --
the content holds throughout.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The layers took care of the steady state -- the transcript's content
re-recorded fifteen times in a thirty-second scroll, and the frame's
draw phase sits at 3.5ms. What is left is entirely spikes, and they are
pages landing: one of those fifteen recordings took 99.9ms on its own,
with the frame after it unable to start.
The cause was a rule that read as caution and was not. A row with no
measured height was retained whatever its distance, on the grounds that
it had just been paged in and was about to be looked at -- but "no
measured height" describes the *whole page*, not the near edge of it, so
eight hundred events' worth of markdown was shaped inside the frame the
page arrived in.
A row that has not been measured now stands in at the average of those
that have, so it is placed and judged by distance like every other row
and is built when the reader comes near it. The average rather than a
constant because these run from a one-line note to a screenful, and the
average row in a conversation is a fair guess at the next one. Being
wrong is cheap here and self-correcting: an estimate is only ever used
above the viewport, and this layout hangs from its far end, so a
correction up there moves nothing on screen.
Checked by scrolling twenty-five swipes into history and back on a real
transcript -- rows stand up as they are reached, and the position does
not shift as the guesses are replaced by measurements.
Second half of the diagnosis from the ai-app-2-6d session.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The piece of a lazy list this had not rebuilt was the render node per
item. Without one, a row's glyphs are recorded into its parent's display
list, and that list is re-recorded every frame the parent is invalidated
-- which, while the list is scrolling, is every frame. With one, the row
is recorded once and afterwards moved by a transform, and the render
thread culls the ones off screen itself.
The draw-phase culling it replaces could not have won, and the two are
mutually exclusive rather than complementary: `onScreen` and `RowWindow`
read the scroll position from inside every row's and every block's
drawing, and reading a scroll position during draw invalidates the
drawing it is in. So the machinery for deciding which rows need not be
drawn was re-recording all of them, every frame, to decide it. Keeping
both would have bought the cost of the first and none of the second.
Measured on the emulator over a thirty-swipe scroll: **one** row display
list recorded across 481 frames, against 1,544 recordings for the same
gesture before, and the frame's draw phase down from 4.2ms to 2.9ms at
the median.
Two things this also corrects. `LAYOUT_MEASURE_DURATION` is the *View*
hierarchy's pass, and Compose is one view -- `AndroidComposeView.
dispatchDraw` calls `measureAndLayout()` before it records, so all of
Compose's own measurement, text shaping above all, is reported inside
DRAW_DURATION. Every "layout is 0.0ms, so nothing is being re-measured"
reading in this file's history was reading a bucket that never contained
it. And the retain window is now load-bearing for a second reason: a
retained display list costs memory, so bounding what is retained bounds
that too.
Found by the ai-app-2-6d session reading the render reports against this
code; the diagnosis and the ordering are theirs.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
A page of history landing recomposed every loaded row and everything
inside it -- 701 compositions for 148 rows in one of Iris's scrolls,
which is four rebuilds of the whole visible transcript, markdown and
all. That is what her `waited` at the 90th percentile was: the frame
could not start because the thread was rebuilding rows whose content had
not changed.
Nothing was stopping Compose skipping them except that it could not
prove it was safe to. Stability is inferred from a class's fields and a
`List` field makes it assume the worst, so `TranscriptItem`,
`TranscriptRow` and `ParsedReplies` were all treated as things that
might change underneath a composable at any moment. They are not: a row
is rebuilt from the transcript rather than edited, two rows describing
the same events are equal, and the parse cache is keyed on the text it
parsed. Saying so is the whole change.
Measured on the emulator over the same scroll: 139 row compositions, and
**15** of them rebuilt the message inside. The other 124 skipped
straight past the markdown, which is where the cost was. The
transcript's own draw came down with it, from 3.1ms mean to 1.2ms.
The promise these annotations make has to stay true -- nothing described
by them is mutated after it is built. It is not today, and the note on
`TranscriptRow` says so where somebody adding a field will read it.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The frame is now failing to *start* rather than taking too long once it
has: 21ms of `waited` at the 90th percentile against a median frame of
8.8ms that is inside budget. What is holding it up arrives with a page
of history -- 1.5 seconds of markdown parsed in a twelve second scroll,
all of it work nobody is waiting for.
Off the composing thread was the right call and it is not the same as
free. The default dispatcher sizes itself to the machine, which is right
for work somebody is waiting on: a page's worth of parses takes every
core, and the thread that draws the frame queues behind one of them. Two
threads, and a yield between messages, leaves the phone somewhere to run
the frame.
Nothing here makes the parsing faster, and it should not: the whole
point of doing it ahead is that its duration does not matter. What
matters is that it stops being in the way.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Iris's readings made the shape unarguable: smooth with one page loaded,
a step worse at the next, worse again at the one after, and 62.7ms at
the median by 390 rows -- with layout at 0.1ms and the GPU at 1.8ms the
whole time. The cost was following what was *loaded* rather than what
was on screen, and keeping every row built is the only thing in here
that does that.
So the window is bounded. Eight screens either side stay fully built,
which is about sixteen times what a lazy list keeps: everything somebody
has just read is still there, and only a deliberate journey back through
the conversation pays to rebuild anything. That was the point of
retaining rows and it survives; what does not survive is retaining all
of them.
A row outside the window is replaced by a spacer of the height it was
last measured at, so the transcript's total height is unchanged and
nothing under the reader moves. A row that has never been measured has
no height to stand in for it and is kept whatever its distance, which is
exactly the row that has just been paged in.
Each row decides for itself, in a composable of its own, from a derived
state -- so a row hears about the scroll only when its own answer
changes. Read from the list's body instead, every row would recompose
whenever any row crossed the edge.
On the emulator, same transcript and same gesture, the frame's draw
phase goes from 2.7ms at the median to 0.4ms. Iris's own timing reading
from before this says where the rest of her frame goes: the transcript's
whole draw is 3.0ms mean against a 4.2ms median draw phase, so the
median frame was already close to budget and what is left is the tail --
20ms of waiting and 2.3 seconds of parsing in bursts, both of which
arrive with a page.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The counters did their job and then ran out: 4,090 rows drawn against
94,815 skipped, the tallest drawn block down from 36,982px to 1,765px,
and drawing still took 30.9ms at the median. Almost nothing is being
recorded and recording is still the expensive phase, so the next
question is not "how much" but "where" -- and there are only two answers
left. Either the little that is drawn is somehow costly, or the time is
not inside the transcript at all and every count above is beside the
point.
So the draw is timed at three levels that nest: the whole transcript,
one row, one block. If the transcript's own figure is most of the
frame's draw, the cost is ours and the rows and blocks say which. If it
is a fraction of it, the frame is being spent somewhere this has not
been looking.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
A reply's display list holds every glyph of it and is re-recorded
whenever drawing is invalidated, so one long message costs as much to
draw as a hundred short ones and skipping the rows around it cannot help
while it is the one on screen. That was the whole of the remaining draw
cost: 97% of rows correctly skipped, and the tallest one still drawn was
36,982px -- about twenty-five screens in a single message.
So a message is cut into its top-level blocks and each is drawn, or not,
on its own. The cut comes from the parser's own boundaries rather than
from a line scanner looking for blank lines, which is what makes it
safe: a heading, a table, a fenced block and a list are each one node
whatever is inside them, so a loose list does not become five one-item
lists and a fence is never split down the middle. Checked against a real
reply whose list items are separated by blank lines -- it still draws as
one list with its bullets aligned, which is the case a blank-line split
gets wrong.
It bounds parsing too, which was the other symptom in the same reading:
one message took 1.4 seconds to parse as a single unit, and a block is a
paragraph.
The row and the message each know half of where a block is, so they meet
at an interface declared where it is used: the list supplies the row's
position, the message supplies the block's offset inside it, and drawing
a message does not have to know it is inside a transcript.
What this cannot divide is a single node, and a long fenced code block
is one -- so the report now also carries the tallest *drawn block*,
which is the number that says whether splitting bounded anything. This
emulator's tallest row is one such fence, which is why its own figures
do not move.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
"Drawing costs too much" and "drawing was skipped and still costs too
much" need opposite fixes, and a millisecond figure cannot tell them
apart. So the report now carries how many rows were drawn, how many were
skipped, and the height of the tallest one that was drawn.
The first reading answers it. Skipping works -- 854 rows drawn against
24,078 skipped, so 97% of the transcript is correctly not being recorded
-- and the tallest row that *is* drawn is 36,982px. One assistant message
about twenty-five screens tall, whose display list holds every glyph of
it, re-recorded whenever drawing is invalidated. A row that size is a
hundred short rows as far as the draw phase is concerned, and no amount
of skipping its neighbours helps while it is the one on screen.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Iris's Pixel 9 Pro XL said which half was costing, and it was not the
half either of us was looking at. With 138 rows loaded: layout 0.0ms at
the median, GPU 1.9ms, and **draw 13.6ms** against a 120Hz budget of
8.3ms. Nothing was being re-measured and the phone's rasteriser was
idle; the UI thread was recording draw commands for a transcript that
was almost entirely off screen.
Retaining rows was right and stays. What does not follow the same rule
is drawing: the draw pass walks the whole tree, so a list that keeps
every row alive records every row every frame, and that cost grows with
each page of history -- which is exactly what "worse afterwards" was.
Composition and measurement are what must not be thrown away, because
they are what has to be rebuilt from nothing when the reader comes back.
A display list is rebuilt from a layout that is still there.
So each row skips its own draw when it is off screen, by more than a
screen's margin either side. The check reads the scroll position from
the draw phase, so moving the list invalidates drawing and nothing else,
and it is a lookup rather than a sum -- the running totals are rebuilt at
most once a frame and only after something has actually changed height,
since adding them up per row per lookup would have made the fix
quadratic in the thing it was fixing.
Also reports the three frame phases that were missing, which is why the
phases on that reading did not add up to the total: the time a frame
spent waiting for the UI thread to be free, handling input, and running
animations. About 15ms of the 30.6 was in that gap and unattributed.
On the emulator, same transcript, before and after: draw p50 3.9ms ->
2.5ms, p90 7.3ms -> 4.2ms, p99 48.6ms -> 5.2ms. The saving there is
small because only 60 rows were loaded; it is proportional to how much
is off screen, and on the phone that was 95,000px of content against a
1,474px viewport.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
A speedometer left of the usage chart, because it is the same kind of
thing about the app that the chart is about the conversation. It copies
rather than opens: a screenful of timings read on the phone is a
screenful nobody can act on, and what it produces is a message to
whoever is looking at the code.
It carries both halves of the question, because "the scroll is laggy"
has two causes and one appearance. From the platform, each frame's cost
split into its phases -- if measuring and drawing are small and the
total is large, the time is going into rasterising and no amount of
doing less work per row will move it. From the app, counts and timings
of the work the transcript actually does: rows composed, replies parsed
on the composing thread rather than ahead of it, runs grouped.
Counts rather than frame times are the point of the second half. This
emulator scrolls at the same 21ms median as the stock Settings app, so
every app-level cost here is under the floor of what it can measure and
no number taken in it says anything about a 120Hz phone. How many times
a row was composed is the same number on any machine, and it is the one
that says whether the work follows what is on screen or everything ever
loaded.
Pressing it empties both, so two presses measure two separate stretches
of scrolling rather than one and then the same one again.
The first reading from the emulator already says something: measure and
layout are 0.0ms at the median, so nothing is being re-measured, and the
cost is 3.9ms of recording the draw against 10.9ms of GPU. It also shows
60 loaded rows composing 177 times across three page loads -- every row
recomposing whenever a page lands -- which is the next thing to look at
if the phone says the work is ours.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
`onPlaced` on the transcript content is the one callback left that would
run every frame, and on all but the two frames of a restore it looks at
a null and returns. Attaching it only while a position is waiting says
that in the modifier chain rather than in a branch inside it.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Asked for: more space between the header icons, and a box tall enough to
fill the header rather than sitting inside it. 48dp does both -- the marks
stand 31dp apart and 31dp from the screen edge, measured on the emulator,
where the 40dp square had them 23dp apart and 27dp from it.
It is also the platform's minimum touch target, which the previous size
was short of, and it is taller than any header's text: the session
header's row now takes its height from the button and needs no vertical
padding of its own, for the same reason the rows add no gap between two
buttons. The ring around the mark is still the only spacing rule; every
number here moved because it did.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Holding every row alive turned two per-row callbacks from a cost paid by
whatever was on screen into a cost paid by everything ever loaded, which
is why loading one more page of history made the whole transcript lag
and each page after made it worse. Both fire for every registered node
on every layout pass:
- an `onGloballyPositioned` per row, kept so a tap could be told which
half of the row it landed in
- an `onGloballyPositioned` per clickable inside a row, for the same
reason, so a tool group paid several
Neither is needed. One gesture detector on the whole list records where
a touch went down in the content's own coordinates, and the row's own
start is added up from heights when somebody actually taps -- so the
transcript keeps a height per row, which changes when the row does, in
place of a position per row, which is wrong the moment anything scrolls.
Positions for the saved-scroll anchor come from the same sum, and the
anchor is applied once per layout from the content rather than once per
row.
The reply cap is gone at Iris's request; she wasn't seeing it and does
not want it for now. It was doing measurable work -- p50 rises from 16ms
to 20ms on the emulator with it removed -- so it is worth knowing where
to look if long history feels heavy.
That 4ms is the only figure here I trust. This emulator's own noise
between identical repeats is larger than the difference the callback
change makes (identical builds measured 3.5% and 9.3% of frames over
budget), and its p50 of 16ms is already past a 120Hz budget, so it
cannot rank any of this the way the phone will. The callbacks are gone
because they are O(rows) per frame by construction and the list no
longer bounds how many rows there are -- not because a number here says
so.
Checked on the emulator against a real 1,200-event transcript: tapping a
collapsed row expands it with its top edge held exactly still, and a
scroll position comes back pixel-identical after leaving the session and
returning.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Every gap around a header icon now comes out of the button's own padding:
one ring to the screen edge, two where a button meets its neighbour. The
box was the size of the mark (28dp) and the separation was bolted on
beside it, so on the session header the two marks stood 31dp apart while
the outer one was 14dp from the edge of the screen -- a pair that acts on
one screen reading as two unrelated marks, one of them falling off it.
Measured on the emulator at 40dp: 23dp between the marks, 27dp to the
edge, and the same ring above and below.
The mark was also not square, which is why an arrow looked taller than it
was wide. `Glyph` is a `Text`, and it inherited the body style's 24sp line
height around a 17sp mark; this font's ascent and descent add up to
exactly one em, so a line height of the point size is the square the glyph
draws in. That leading is also what a button's padding had to be measured
through.
40dp is Material's own icon-button state layer, and it is what the
pressed-state ripple draws -- at 28dp that circle was inscribed in the
mark's corners, and beside a title it arrived at the first letter. The
touch target comes up with it, from well under the platform's 48dp
minimum to within 8dp of it; going the rest of the way would put the marks
back 31dp apart.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The transcript is a plain Column scrolled in reverse instead of a
LazyColumn. Nothing about Compose was re-measuring text that had already
been drawn -- a node that is still alive and whose constraints have not
changed skips measurement outright, in MeasurePassDelegate.remeasure.
What was throwing that away was disposal: a lazy list drops a row the
moment it leaves the viewport, and the markdown tree, the measured lines
and the cached paragraph go with it. Keeping the rows is the fix, and it
is what a browser-based client does that we were not.
Two scroll corrections go with it, each of which had a comment
explaining a way it had been seen to fire at the wrong moment. The
content now hangs from its newest end, so a page of older history
extends the far end and moves nothing on screen, and an arriving message
extends the end the viewport is already pinned to. Following the newest
message is no longer an effect that notices and corrects; it is where
the content is. The same goes for the keyboard opening, which was the
case that used to get missed.
Paging asks its question in pixels of scroll -- how far can the reader
keep going before they run out -- which is what it was always about.
Rows were the wrong unit twice: a fixed count of them is a distance only
by accident, and counting screenfuls of rows fixed the size of that
mistake without fixing its kind.
A saved position is resolved to the row that now holds that seq before
the layout is asked to put it back. The events behind a row regroup
between the save and the reopen, so the seq that was a row's first is
often no longer any row's first, and handing the layout the saved seq
named a row that did not exist -- the position was never applied and the
session opened at the newest end.
Verified on the emulator against a real 1,200-event transcript: the
position survives leaving and reopening, jump-to-latest arrives and
stays followed, and the newest message holds its place against the
composer as the keyboard opens and the draft grows. Scrolling measures
the same as the lazy version did (2.6% vs 2.0% janky, p50 16ms, p90
21ms, no slow UI-thread frames either way) -- the cap and the
off-thread parse had already taken that cost out, so this change is
about what the list can no longer do wrong rather than about frames.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Iris approved the cap and set the one exception: never the latest
response. That one is being read as it arrives, often still arriving, and
putting "show the rest" under the turn somebody is waiting for hides the
answer they are waiting for. Everything behind it is history, which is
what this is for.
The limit is on the **source**, not on the height, and that is the whole
point. Clipping a laid-out row to a height saves nothing -- Compose
measures the text and throws the overflow away, so the line-breaking has
already happened -- while cutting the string before it is parsed stops
the work being done at all, the parse included. Four thousand characters
is about two screenfuls, with a thousand of slack so that a reply barely
over the limit is not given a control worth nothing to anybody.
The cut is at a line ending, because a markdown source cut mid-line is a
different document: half a heading marker, a list item with no bullet, a
link whose closing bracket was dropped. A fence left open is closed,
which is the one case a line boundary does not cover -- an unterminated
``` swallows the rest of the reply into a code block, so the truncation
would change how the part still on screen is *drawn* rather than only how
much of it there is, and a reader cannot tell that from the reply
genuinely having been code. Verified against a reply whose cut lands
inside a 400-line Rust block: the block renders as a block, closes, and
the control sits below it in ordinary text.
`markdownIn` now names both forms, because which one a row draws is not
decided there -- so pressing the control is a cache hit rather than a
50ms parse on the frame it happens in, and neither form is a key that no
row ever looks up.
Measured on the emulator, now that it renders on the GPU and its frame
numbers mean something -- two flings over replies of the same size in the
same session, one capped and one not:
uncapped 62,310 capped 54,990 (4,000 drawn)
janky (legacy) 58.20% 11.33%
slow UI-thread frames 5 1
p50 23ms 16ms
p90 30ms 24ms
The modern "Janky frames" figure is 4.04% against 3.59% -- near identical,
because both stay inside the compositor's deadline on this emulator. The
win is UI-thread work, which is what was aimed at, and the legacy metric
is the one that counts it.
Expanded is remembered by the screen, beside the other expansion sets, so
scrolling away and back does not shut something deliberately opened.
Known and not fixed: the floating jump-to-latest control is centred at the
bottom of the list and overlaps this one's label whenever a capped reply's
foot lands in that band. It is the overlay's pre-existing disregard for
content -- long replies have always had text under it -- but a control
there is worse than prose, and it is now common rather than incidental.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The five-hour window's reset time is absent between blocks, because the
window is anchored to the block it started in and there is nothing to reset
until one is running. Measured against a live response: the reset came back
as exactly five hours after work resumed, and the weekly windows in the same
response carried the identical microsecond, so both are computed from one
now() at request time. The weeklies always have a reset because a week is
always running -- which is why only the five-hour row looked wrong.
`remainingUntil` returned null for that and for a timestamp it could not
parse, so the session bar announced "reset time unknown" about a machine
behaving perfectly, on the one row somebody reads before starting something
big. The usage dialog, looking at the same field, drew nothing at all and
printed a raw ISO string when a parse did fail. One missing value, two
rules, and neither of them right.
`WindowEnd` names the three answers and both callers go through it. A window
that is not running shows its percentage and no countdown, in the bar as
well as the dialog; an unreadable timestamp says so in words rather than
showing itself.
Looked at both on the emulator, the second by making the server drop the
field: 15% with "4h 43m left" when a block is running, "13%" alone when none
is, and the dialog's five-hour row with no reset line beside weeklies that
have one.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Two places said the history cushion's evidence was a swipe that moved
nothing for 689ms. That reading came from `ui-trace show` on a row taller
than the viewport, which reports clipped bounds and so prints "nothing
moved" for a list that is scrolling fine -- and it was taken on the software
renderer besides. The finding it supported is sound and has a better
witness: counted at the server, ten swipes asked for ten pages before the
change and three after, which does not depend on how anything renders.
Also records what the screen actually costs now, measured on the GPU
emulator: 5.2-5.9% janky frames and 0-2 slow UI-thread frames flinging fast,
against 3.3% for the stock Settings app on the same device. With the note
that matters for repeating it -- let the screen settle before resetting
gfxinfo, because the first seconds after opening a session are every row
being composed for the first time and read three times worse.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Now that a scroll anchor is a seq, the restore knows exactly how far back
it has to reach, so it asks for that span in one request instead of
walking there a page at a time. ai-app-2 suggested it; the arithmetic is
theirs. `read_window` counts lines and a transcript numbers them one per
seq, so the distance to the anchor is the number of events to ask for --
and were seqs ever sparse, that difference is larger than the count,
which overshoots into older history rather than stopping short.
Capped at [RESTORE_PAGE_MAX], and the loop already there is what makes
the cap safe: a span past it comes back in several requests rather than
one, which is what every restore did until now. The bytes are the same
either way -- every row between the anchor and the newest end has to be
loaded for the list to be able to count to it -- so this only trades
round trips against response size.
Measured on a 16,133-event session, restoring to seq 2000 (14,133 events
back, the extreme case): **19 requests before, 5 after.** The realistic
case, a couple of thousand events back, is 4 before and 2 after. At
`--delay 150` the deep one puts the row on screen at 5.7s and the
moderate one at 2.5s, and in both the row does not move once it lands.
Also: `RUST_LOG` did nothing. `with_env_filter("info")` is a fixed
directive that never reads the environment, so the per-request page
diagnostics AGENTS.md tells you to turn on with `RUST_LOG=ai_server=debug`
printed nothing at all -- which reads as the code you are instrumenting
being wrong rather than as the switch being disconnected. It is a
fallback now, so the default is still `info`. Those diagnostics are what
the request counts above were measured with.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Three entries under "Things that have bitten": the whole-file read behind
every page, the fact that a page is events and a screen is rows with no
fixed ratio between them, and the withContext that wrapped the fetch and
left the work done with the result outside it. Each carries the number it
was measured at, since the shape of all three is that the cost grows with
the conversation while the answer stays one screen.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Three things, all of them the same complaint: scrolling back through a long
session stalls.
**The fold was on the main thread.** Only `fetchTranscript` was inside
`withContext(Dispatchers.IO)`; the fold loop that turns a page into rows ran
on the caller's dispatcher, which is Main. `foldEvent` returns a new list
per event, so a page is that many copies of a list growing to that length --
about three hundred thousand element copies -- run in the middle of the
scroll that asked for it. Affordable at 80 events per page and not at 800.
**`warm` scanned the whole transcript on the calling thread.** Only
`replies.warm` was off it; the `markdownIn` split that decides *what* to
parse ran before the hop, over every assistant message loaded, on every
page. The scan grew with the conversation while the work it found stayed one
page's worth.
**The cushion was eight rows, which is not a distance.** A row is anything
from one line to a page: on a tool-heavy transcript eight rows is less than
one screen, so the reader reached the end of what was loaded on every swipe
and waited a round trip standing there. It is three screenfuls now, measured
from what is actually on screen. On the emulator against a 24,000-event
transcript that is 3 page fetches for 10 swipes rather than 10.
Also a spinner while a chat loads. Nothing is drawn while the newest page is
in flight or a saved position is being put back, and a blank page is what
this screen otherwise means by "there is nothing here" -- so the state that
does not know needed its own appearance.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
A command, a tool's output and a code block in a reply are the one thing on
this screen that is not somebody's prose, and they now say so: Mocha's
Crust, which sits below Base, so the same colour is one clear step down both
on the page where a reply is drawn and on the card where a tool call is.
The renderer's code background was `surfaceVariant`, which is exactly a
card's own fill -- a fenced block inside a tool call had no background at
all, and one in a reply read as a step *up* out of the page.
Tool output takes the monospace face with it. It is column-aligned far more
often than it is prose -- a listing, a diff, a table of numbers -- and a
proportional font silently destroys the alignment that carried the meaning.
`RawBlock` is a composable rather than a modifier because the inset is part
of it: monospace text against the edge of a tinted block reads as clipping.
A call with neither a subject nor any other field draws nothing at all
rather than an empty tinted rectangle.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Every page-back re-read and re-parsed the whole transcript and then threw
away all but the window. That is the cost that grows with the conversation
rather than with the answer: measured on a 21 MB, 24,000-event transcript,
one page took ~500ms of server time to return 620 KB, and it took the same
500ms whichever page was asked for. A phone scrolling up pays that per
page, and every stream reconnect pays it again to discover there is nothing
new.
Sequence numbers only increase, so the boundary of a range is a bisection.
`Indexed` locates the lines without reading them, finds the edge by parsing
one line per halving, and parses only what is going to be returned. Same
page, 232ms including the 120ms `--delay` -- so ~110ms, of which ~20ms is
the file scan and the rest is serialising the 620 KB that was always going
to be sent.
`catch_up` gets it too, and there the case that looks least interesting is
the one that mattered: a subscriber with no cursor asks for the whole
conversation and is handed the last CATCH_UP_LIMIT events of it.
The file is still read whole, which is a deliberate stop -- finding the
tail without reading forwards means a chunked backwards reader, and
locating a line is not what the half-second was going to.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
ai-app-2 found the reason a session Iris had scrolled in took a while to
open, and it is a defect in what I shipped this morning. A `ScrollAnchor`
stored the list's own row key. That key looks stable and is not: a tool
row is named after its run, `joinPages` gives a run the name its *newest*
half carries, and the newest half is whatever the newest page happened to
start with. The newest page is the last eighty events, so the name is
fixed for an idle session -- which is why this passed on the emulator --
and changes the moment the session says anything. An active session
therefore renamed its tool runs on every reopen, the anchor was never
found, and the restore paged backwards until there was no history left,
i.e. to the first event of the conversation.
So the anchor is a sequence number now, taken from the oldest event
behind the row. That is the server's own numbering: assigned once, never
moved, the same on every device. The restore finds the last row starting
at or before it, so it still lands correctly when grouping has changed
underneath it -- a run folding differently, two halves of a reply
becoming one message -- and the page-back loop gains an exact stop,
because `oldestSeq` walks strictly backwards and a row always matches
once the window passes the anchor. It cannot run to seq 1 any more.
`TranscriptRow` now carries `startSeq` beside `key`, and the two are
documented against each other: `key` is the list's identity and a display
decision, `startSeq` is a place in the conversation. Anything that has to
point at a place and find it later uses the second.
Two more found while testing this, both the same shape -- a listener
waiting for a scroll to *end* never runs when the list moves inside one
frame:
- The anchor was read from `rows`, which a `LaunchedEffect(listState)`
captures from the first composition, where it is empty. Every scroll
saved a null anchor, indistinguishable from being left at the newest
end, so the position was silently never recorded at all. It reads the
live state now, as the paging code beside it already warned it must.
The anchor is also written from the settled *position* rather than from
the scroll flag, because Jump to latest snaps within one frame: it left
the old position recorded, so pressing the control that means "take me
to the end" and coming back put the reader where they had been.
- Jump to latest did not set `followTail` either, which is the same hole
in the sibling and predates today: the view landed at the bottom with
following switched off, and the next message did not bring it along.
The button states what it means now. `followTail` itself stays on the
scroll settle, deliberately -- a keyed list moves its own anchor when a
row arrives, so the position reports itself as scrolled back for a
frame every time a message lands, which is the whole reason that value
is remembered rather than read.
Verified against an echo session grown to 1,327 events between saving the
position and reopening, so the newest window slid and the runs were
renamed: the same row is on screen before and after, it appears 419ms in
and never moves, and a 200-piece streamed reply still follows the bottom
after a jump.
The threading of `loadOlderPage`'s fold is ai-app-2's, not touched here.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Five things Iris asked for, all about the transcript screen holding still
around whoever is reading it.
A tool call opened on its own stayed open when a second call in the same
run turns it into a group. Watching a Bash call and having the session
make another one used to shut the card being read and fold it behind
"Called 2 tools" -- the reader lost their place because something else
happened. The transition is noticed once, at the moment a run first
becomes a group; after that the group's own toggle owns it, so shutting a
group whose inner call is still expanded does not re-open it.
The compaction clock is taken from the `compacting` status event's own
timestamp rather than from this device noticing one, so it survives
leaving the session and coming back -- it used to disappear, because the
only thing that knew when the compaction started was a screen that had
been disposed. The server timestamps every transcript line, so this is
still a measurement; it is compared against the phone's wall clock, which
is the same comparison a session's "last active" already makes.
Session settings are a dialog over the session instead of a screen below
it. Two controls did not warrant a page transition and a back stack, and
the thing they change was hidden while they were on screen. Captions are
gone -- each control is a labelled noun -- and "Notify me" is
"Notifications" with a bell beside it (`md-bell`, added to the committed
Nerd Fonts subset). Failures keep their words, since those are what a
reader cannot work out by looking.
Tool groups are rounded like every other card, their foot bar is the same
height as their heading (both derived from the heading's own line height,
so the pair cannot drift), and the calls inside are a connected stack:
square where they face a neighbour, rounded on the outside, with a small
gap so the join reads as a join.
Scroll position is persistent on the device, per session, keyed by the
row rather than by an index -- an index means nothing across a reopen,
where the transcript is fetched newest-first. Reopening pages backwards
until that row is loaded *and* has something older behind it, because the
oldest loaded row is a half-row that grows when the page behind it
arrives; anchoring into one landed a screen and a half out. The list
draws nothing until the position lands, so there is no frame in which the
transcript is somewhere other than where it was left.
Two things found on the way. `snapshotFlow`'s first emission is the state
before anybody has touched the list, and reading it as a scroll that had
just ended at the newest end wiped every saved position on the way in.
And backwards pages now ask for 800 events rather than 80: ai-app-2
measured a real transcript at 2,426 events for seven assistant messages,
so a page of eighty is a fifth of one row and filling the lookahead took
about thirty sequential round trips -- seconds of a list that will not
move, over the tunnel.
`/tools [n] [gap]` in the echo driver takes seconds between calls, which
is what makes a run grow slowly enough for somebody to have opened one of
its calls first.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
--throwaway-sessions, on by default in a debug build. Every session a
server started with it spawns is marked throwaway in the config, and a
marked session's process is stopped when the server exits or is
signalled, rather than left running for the next start to adopt.
Leaving processes running is the design and it is right for the sessions
somebody is using. It is exactly wrong for the ones a test made: those
leave a claude behind that every later server adopts, and nothing ever
says they are there -- twelve accumulated on this machine in a day, each
holding a conversation open.
The flag marks; the mark decides. What a server was told at startup
governs only the sessions it spawns, and the mark is the session's own,
so a session spawned deliberately keeps running whichever server is up
when one exits, and a throwaway one is cleaned away even by a server
started without the flag.
process::wait_gone does the waiting on the way out, because
process::stop leaves its SIGKILL on a tokio timer and a runtime that is
shutting down never runs it -- which is how the original shutdown_all
leaked the processes it reported stopping.
Its test found a second thing, in the same field the last commit was
about: a zombie read as Alive. /proc/<pid>/stat keeps the entry, with
the same pid and the same start time, until the exit status is
collected, so a process that had plainly finished answered "still
there" -- and Alive is the word that makes Exited unsayable, so the
session shows unknown, its Start button never appears, and Stop says
there is nothing to stop. stat_of reads the state field alongside the
start time now.
Exercised against a real server: a keeper spawned with the flag off
survives its server's exit and is adopted by the next one, a session
spawned with it on is stopped on SIGTERM within 20ms, and the
"left N running" line counts what is actually still out there.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
From the ai-app-2 session, which used it to find a clock bug the tests did
not have. A `claude_cli` provider pointed at `#!/bin/sh` / `cat > /dev/null`
behaves the way the lifecycle code cares about -- holds the fifo open, records
a real pid, writes nothing, dies on a signal -- so adopt, stop, restart and
start are drivable without a real `--resume` and without spending a turn on
somebody's account.
Written down beside `debug-transcript.sh` because the two answer different
questions and the wrong one is expensive: this for whether a process is
running, that for what the transcript draws.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Restarting the server relaunched a driver for every session in the
config, and ClaudeDriver::launch starts a process when there is none to
adopt -- so a session somebody had deliberately stopped came back at the
next rebuild, and the Idle its new driver announced stamped the session
as active at that moment. On the phone that read as every session idle
and "just now" after every restart, with the list sorted by that time in
an order that meant nothing.
A launch now says why it is happening. Launching::Restart takes charge
of the processes still running and leaves every other session as it
found it; Launching::Asked -- a spawn, a Start, a message -- starts one
where there is none. A session with no process therefore has no driver:
DriverCell is an option rather than a driver whose requests go nowhere,
and LiveSession::ask reports what could not happen instead of sending
into a dead fifo.
Two clocks that moved on their own, both the same lie in the same field
that Transcript::last_activity exists to prevent:
- The status a launch has to correct is written into the transcript at
the time of the last thing the session actually did. A backend killed
mid-turn leaves a transcript saying Running, which has to become
Exited -- but this server noticing is not the session doing something.
- A session that has never done anything reports when it was created. Its
transcript is empty, since a driver announcing the state it starts in
is not news, so it is the one session with no line to read a time off
and the clock was the fallback.
Exercised end to end against a real server: a stand-in CLI adopted
across a restart keeps its status and its time, a stopped session stays
stopped with no process started, a process killed while the backend was
down reports exited stamped at the last thing the session did, and Start
brings it back.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Both faults needed a real conversation to see, so `app/debug-transcript.sh`
now puts one on the emulator: it copies a Claude Code transcript into /tmp,
gives an ai-server a HOME of its own so the import can only see the copy, and
enrols the app against it. The transcript itself never enters this repository
-- those files hold whatever was said, read and written in a session. Beside
it, `ai-server --delay MS` holds every response back, because a phone's
requests take tens to hundreds of milliseconds over the tunnel and several
faults live entirely in what the app does while one is outstanding.
**Scrolling up threw the reader back to the newest end, once.** `followTail`
is deliberately a remembered answer, rewritten only when a scroll settles, so
for the whole of a fling it still reports the newest end -- where the reader
was when they threw it. A page of history landing during that fling is a
change in the item count, and the correction written for an insertion at the
newest end fired for one at the oldest. Captured on the emulator:
scrolling=true atNewest=false followTail=true
history: START last=20 total=28
history: page of 80 events -> rows now 36
countChanged count=36 followTail=true scrolling=true
>>> scrollToItem(0) SNAP
It could happen only once, which is what made it look arbitrary rather than
mechanical: the snap settles the scroll at the newest end, so the next fling
gets far enough to settle away from it, and from then on `followTail` is
false. So the list is no longer moved while a scroll is running, which is a
rule of its own rather than a refinement of that condition -- and skipping
the correction outright is right rather than merely safe, because the count
can only grow at the newest end while the reader is already there, `record`
holding everything else until they come back.
**A page of history stalled the frame it appeared in.** Parsing is the
expensive half of drawing a reply and costs in proportion to what was
written: against this transcript one message took 51ms and several took
10-25ms, where the synthetic replies this was tuned on took 4.6ms. So each
page's replies are parsed on a background thread as the page arrives --
after the join, since a boundary falling through a reply leaves a message
made of both halves whose text has existed for no time at all, and warming
the page alone warmed the two halves and missed the one thing drawn. A row
with no answer waiting still parses inline: a row measured at nothing before
it is measured at its real height collapses the transcript above it. Misses
are not stored, so a reply still streaming cannot fill the map with copies
of itself on the way to being finished.
Measured over the same twelve flings: 13.5ms average per composed reply
before, 7us after, the remaining parse being one message at session open.
Verified with ui-trace at 1kHz: with a page landing mid-drag the suppression
fires and the row the reader is on moves monotonically down, 266 -> 1063,
with no step backwards; at rest 0 of 65 elements move. 86 server tests pass,
ktfmt/lint/clippy clean.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The last commit left renaming out on the grounds that the name is
persisted and listed whether or not a process hears about it. That was
wrong, and Iris said so: Claude Code keeps its own copy of the name,
that copy is what its session picker shows and what other agents read
when they list sessions, and a session is only ever *given* a name at
birth -- every later start is a `--resume`, which passes no `--name`.
So a rename that reached no process left the two lists disagreeing
permanently, with this app's the only one that had moved. The cost of a
resume buys the one thing renaming is for.
It stays `rename_session` rather than becoming a command like the rest,
because the name is persisted and listed as well as forwarded and that
is one operation. The save happens first and the lock is dropped before
the telling, so a failure to start reports that the telling failed
rather than the rename, which by then has already happened.
`LiveSession::run_command` went with it. It read `shared.status` and
that read is exactly what a just-started session cannot be judged by, so
every caller now goes through the manager -- which is also what the four
tests that used it were standing in for.
Verified against a stand-in CLI that echoes its stdin: a session
reporting `exited` was renamed, the process started with `--resume`, and
the CLI received `/rename after the restart` on stdin. The list shows
the new name and the session reports idle.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Same reasoning as the message path a commit ago, and the same objection
to leaving it out: a command is something somebody asked the session to
do, and answering "its process has exited" hands back the work of
starting one. `/compact` on a stopped session is the case that shows it
-- what is being asked for is exactly what a stopped session needs
before it is useful again.
`POST /sessions/{id}/command` and `/compact` now go through
`SessionManager::run_command`. A rename is deliberately not one of them:
it is persisted and listed whether or not a process ever hears about it,
so starting a CLI to tell it a name would be spending a resume on
nothing. It stays a forward to a process that happens to be there.
A command needs one thing a message did not. `Commands::submit` refuses
on `Exited`, and a driver that has just started a process announces
`Idle` through the sink rather than writing it -- so a command judged
against the session's own status would be refused by the word the start
had just replaced, in a window narrow enough that only a test reliably
hits it. `start_if_exited` returning `Exited` is what says a process was
started, so the status the command is judged against comes from there
rather than from a re-read the pump may not have caught up with. The
test fails without it.
`LiveSession::compact` went with this: `/compact` the route and
"/compact" the typed command were two ways to the same command, and now
there is one.
Verified over the API against a stand-in CLI: with the session reporting
`exited`, both `/clear` and `POST /compact` started the process and were
delivered -- transcript order `idle`, `commandSent`, `running`, `idle`,
with no "this session's process has exited" anywhere.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Refusing was work handed back: read the status word, find the other
button, press it, type the message again. Sending plainly means "do this
now", and `--resume` puts the new process on the same conversation, so
nothing about the message changes -- only whether there was anything
there to read it.
`POST /sessions/{id}/message` now goes through the manager, which starts
a process first when the session is known to have exited. Only on
`exited`: `unknown` has a process that may well be reading its fifo, and
starting a second CLI on that guess is the fault `session::process`
exists to prevent, so the message goes to the driver as it always did.
The Start button and this ask one function, `start_if_exited`, and want
opposite answers from it -- "there is already a process" is a refusal
worth showing to somebody who pressed Start, and nothing at all to a
message being sent. Deciding it in one place under the one write lock is
also what keeps two requests that arrive together from starting two
CLIs.
Verified over the API and on the emulator: with the session reporting
`exited` and the composer showing a play button, typing a message and
pressing Send started the process, delivered the message and ran the
turn -- transcript order `idle`, `userMessage`, `running`, `idle` -- and
the button became a stop.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
irisandClaude Opus 5