docs/RUST.md: bench v2 spec and the emulator smoke run

Iris's ask (2026-09-06): the fling should travel much faster for
stress-testing, plus typing and keyboard phases. Written once into the
P0 box so the iris agent implements the identical four-phase spec --
constants, ordering and report shape -- rather than a second one that
looks the same but isn't.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

app/androidApp/src/main/kotlin/com/example/aiapp/BenchRun.kt

@@ -3,9 +3,13 @@ package com.example.aiapp
 import android.content.Context
 import android.os.BatteryManager
 import android.os.Process
-import androidx.compose.animation.core.tween
+import android.view.View
-import androidx.compose.foundation.gestures.animateScrollBy
+import androidx.compose.foundation.gestures.FlingBehavior
 import androidx.compose.foundation.lazy.LazyListState
+import androidx.compose.ui.focus.FocusRequester
+import androidx.core.view.ViewCompat
+import androidx.core.view.WindowInsetsCompat
+import androidx.core.view.WindowInsetsControllerCompat
 import java.io.File
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.delay
@@ -19,27 +23,84 @@ import kotlinx.coroutines.launch
  * here against [LazyListState] and [BenchFixture] directly. Only reachable from the `bench` build
  * (see [SessionSettingsDialog]'s `onRunBenchmark`), but compiled into every build for the reason
  * [BenchFixture]'s doc comment gives.
+ *
+ * **v2 (2026-09-06)**, asked for by Iris because the v1 fling was too gentle to stress-test the
+ * scroll path and said nothing about typing or the keyboard. Four phases now, each a slice of the
+ * same [FrameStats] recording ([FrameStats.markPhase]/[FrameStats.phaseLines] -- one recorder, not
+ * two): **fling** (real `FlingBehavior`, not `animateScrollBy`), **stream** (unchanged from v1),
+ * **type** (600 fixed characters into the real composer `TextFieldValue`, then deleted), and
+ * **keyboard** (five show/hide cycles). The exact constants below are also written into
+ * `docs/RUST.md`'s P0 box, "Benchmark v2 (2026-09-06)", so the iris half implements the identical
+ * spec -- changing a number here without updating that box makes the two apps measure different
+ * things while looking like the same benchmark.
  */
 object BenchRun {
-    /** transcript-bench.sh's default: 6 cycles of 4 swipes each, 900px over 200ms, 500ms apart. */
+    /** transcript-bench.sh's default: 6 cycles of 4 swipes each, kept as the pre-v2 comparison. */
     private const val CYCLES = 6
     private const val SWIPE_PX = 900f
     private const val SWIPE_MS = 200
     private const val SWIPE_PAUSE_MS = 500L
 
+    /**
+     * Fling phase (v2): a real fling through the list's own [FlingBehavior], not `animateScrollBy`
+     * -- Iris's ask was that it "travel way faster" than the old tween-based swipe, and a tween can
+     * never exceed the distance it is told to cover in the time it is given, while a real fling
+     * decays from an initial velocity the way a finger flick does. 12,000 px/s is roughly a hard,
+     * fast flick on a ~420dp/in device (about 30 dp/ms-equivalent initial speed); chosen well above
+     * the ~4,500 px/s a moderate `animateScrollBy` swipe implies, so this phase exercises the fast
+     * end of what the platform's fling decay produces rather than the gentle one v1 measured.
+     */
+    private const val FLING_VELOCITY_PX_S = 12_000f
+
+    private const val FLING_COUNT = 8
+    private const val FLING_SETTLE_CAP_MS = 3_000L
+    private const val FLING_PAUSE_MS = 300L
+
     /** stream-bench.sh's shape: a real reply arrives as many small deltas, not one big write. */
     private const val STREAM_EVENTS_PER_SEC = 20
     private const val STREAM_SECONDS = 20
 
     /**
-     * Scrolls, then streams, then returns the extra report lines P0 asked for (CPU time, peak RSS,
+     * Type phase (v2): sentences built from long, multisyllabic words so the composer actually
-     * battery current) -- [FrameStats] and [DebugStats] are reset first, exactly as
+     * wraps across lines rather than fitting one, and long enough (600 chars) that the composer's
-     * `copyRenderReport` resets them, so the two accountings cover the same stretch of work.
+     * own height grows over several frames, pushing the transcript above it upward the same way a
+     * real long message does. Exactly this string is also in `docs/RUST.md`'s P0 box so the iris
+     * half types the identical content.
+     */
+    const val TYPE_TEXT =
+        "Benchmarking this transcript screen requires unusually long, multisyllabic words so " +
+            "wrapping and reflow are properly exercised: internationalization, " +
+            "counterproductiveness, disproportionately, incomprehensibility, " +
+            "deinstitutionalization, uncharacteristically, overenthusiastically, " +
+            "misunderstanding, straightforwardness, telecommunications, and interdisciplinary " +
+            "collaboration all push a narrow composer field to wrap across several lines while " +
+            "the transcript above is pushed upward by the growing keyboard-adjacent box, which " +
+            "is exactly what a real reader typing a long message sees happening now!!!"
+
+    private const val TYPE_CHAR_DELAY_MS = 50L
+
+    /**
+     * Keyboard phase (v2): five show/hide cycles, a second apart, is enough to see whether the
+     * transition is ever actually observed rather than being a one-off fluke either way.
+     */
+    private const val KEYBOARD_CYCLES = 5
+    private const val KEYBOARD_SHOW_WAIT_MS = 1_000L
+    private const val KEYBOARD_HIDE_WAIT_MS = 1_000L
+
+    /**
+     * Scrolls, flings, streams, types and toggles the keyboard, then returns the extra report lines
+     * P0 asked for (per-phase travel/typing/keyboard counts, plus CPU time, peak RSS, battery
+     * current) -- [FrameStats] and [DebugStats] are reset first, exactly as `copyRenderReport`
+     * resets them, so the two accountings cover the same stretch of work.
      */
     suspend fun run(
         context: Context,
         scope: CoroutineScope,
         listState: LazyListState,
+        flingBehavior: FlingBehavior,
+        composerFocus: FocusRequester,
+        setComposerText: (String) -> Unit,
+        view: View,
     ): List<String> {
         FrameStats.reset()
         DebugStats.reset()
@@ -55,34 +116,10 @@ object BenchRun {
             }
         }
 
-        // The swipe loop: transcript-bench.sh's four swipes per cycle are two drags toward newer
+        val travel = runFlingPhase(listState, flingBehavior)
-        // content and two back, so a cycle returns to where it started and the whole loop measures
+        val sent = runStreamPhase()
-        // steady-state scrolling rather than travelling somewhere new each time.
+        runTypePhase(listState, composerFocus, setComposerText, view)
-        repeat(CYCLES) {
+        val keyboard = runKeyboardPhase(context, view)
-            repeat(2) {
-                listState.animateScrollBy(SWIPE_PX, tween(SWIPE_MS))
-                delay(SWIPE_PAUSE_MS)
-            }
-            repeat(2) {
-                listState.animateScrollBy(-SWIPE_PX, tween(SWIPE_MS))
-                delay(SWIPE_PAUSE_MS)
-            }
-        }
-
-        // Pinned to the newest end before streaming starts, the way stream-bench.sh's "Jump to
-        // latest" tap is -- a reply streamed into a list parked further back arrives off-screen and
-        // the report would show nothing happened.
-        listState.scrollToItem(0)
-
-        var sent = 0
-        val total = STREAM_EVENTS_PER_SEC * STREAM_SECONDS
-        while (sent < total && BenchFixture.remainingStreamEvents() > 0) {
-            BenchFixture.pushNextLiveEvent()
-            sent++
-            delay(1000L / STREAM_EVENTS_PER_SEC)
-        }
-        // Lets the last few deltas land and draw before the report is read.
-        delay(300)
 
         samplerJob.cancel()
         val cpuMs = Process.getElapsedCpuTime() - cpuStartMs
@@ -90,13 +127,158 @@ object BenchRun {
         val batteryLine = battery.finish()
 
         return listOf(
-            "  scroll: $CYCLES cycles (${CYCLES * 4} swipes), streamed $sent/$total fixture events",
+            "  fling: $FLING_COUNT flings out + $FLING_COUNT back at" +
+                " ${FLING_VELOCITY_PX_S.toInt()}px/s, travel $travel",
+            "  scroll: $CYCLES cycles (${CYCLES * 4} swipes, legacy tween), " +
+                "streamed $sent/${STREAM_EVENTS_PER_SEC * STREAM_SECONDS} fixture events",
+            "  type: ${TYPE_TEXT.length} characters inserted then deleted, one per" +
+                " ${TYPE_CHAR_DELAY_MS}ms",
+            keyboard,
             "  process CPU time over this run: ${cpuMs}ms",
             rssLine,
             batteryLine,
         )
     }
 
+    /**
+     * Phase 1: starting pinned at the newest end, [FLING_COUNT] flings away from it (toward older
+     * messages) through the list's real fling path, then [FLING_COUNT] back. Positive velocity here
+     * matches this list's existing scroll-offset convention (`TranscriptList`'s `reverseLayout`
+     * pins index 0 -- the newest item -- at the bottom; a positive scroll offset moves the viewport
+     * toward higher indices, i.e. away from the newest end and toward older content), the same sign
+     * the pre-v2 swipe loop below already used for its first two swipes.
+     */
+    private suspend fun runFlingPhase(
+        listState: LazyListState,
+        flingBehavior: FlingBehavior,
+    ): String {
+        FrameStats.markPhase("fling")
+        listState.scrollToItem(0)
+        val start = position(listState)
+        repeat(FLING_COUNT) {
+            listState.scroll { with(flingBehavior) { performFling(FLING_VELOCITY_PX_S) } }
+            waitForSettle(listState)
+            delay(FLING_PAUSE_MS)
+        }
+        val outward = position(listState)
+        repeat(FLING_COUNT) {
+            listState.scroll { with(flingBehavior) { performFling(-FLING_VELOCITY_PX_S) } }
+            waitForSettle(listState)
+            delay(FLING_PAUSE_MS)
+        }
+        val back = position(listState)
+        return "start=$start outward=$outward end=$back"
+    }
+
+    private fun position(listState: LazyListState) =
+        "idx=${listState.firstVisibleItemIndex}/off=${listState.firstVisibleItemScrollOffset}px"
+
+    /** Belt-and-suspenders on top of `performFling` already suspending until its own decay ends. */
+    private suspend fun waitForSettle(listState: LazyListState) {
+        val startedAt = System.currentTimeMillis()
+        while (
+            listState.isScrollInProgress &&
+                System.currentTimeMillis() - startedAt < FLING_SETTLE_CAP_MS
+        ) {
+            delay(16)
+        }
+    }
+
+    /**
+     * Phase 2 (unchanged from v1): pinned to the newest end before streaming starts, the way
+     * stream-bench.sh's "Jump to latest" tap is -- a reply streamed into a list parked further back
+     * arrives off-screen and the report would show nothing happened.
+     */
+    private suspend fun runStreamPhase(): Int {
+        FrameStats.markPhase("stream")
+        var sent = 0
+        val total = STREAM_EVENTS_PER_SEC * STREAM_SECONDS
+        while (sent < total && BenchFixture.remainingStreamEvents() > 0) {
+            BenchFixture.pushNextLiveEvent()
+            sent++
+            delay(1000L / STREAM_EVENTS_PER_SEC)
+        }
+        // Lets the last few deltas land and draw before the next phase starts.
+        delay(300)
+        return sent
+    }
+
+    /**
+     * Phase 3: focuses the real composer, shows the keyboard if the platform allows it, then types
+     * [TYPE_TEXT] one character at a time through the same `TextFieldValue` state a real keystroke
+     * updates, and deletes it the same way -- this is what exercises wrapping and the transcript
+     * being pushed upward, not a single big write.
+     */
+    private suspend fun runTypePhase(
+        listState: LazyListState,
+        composerFocus: FocusRequester,
+        setComposerText: (String) -> Unit,
+        view: View,
+    ) {
+        FrameStats.markPhase("type")
+        listState.scrollToItem(0)
+        composerFocus.requestFocus()
+        showIme(view.context, view)
+        // Lets focus and the keyboard's opening animation land before typing starts, so the frames
+        // this phase records are the wrap/reflow it is measuring, not the keyboard opening.
+        delay(300)
+        var typed = ""
+        for (ch in TYPE_TEXT) {
+            typed += ch
+            setComposerText(typed)
+            delay(TYPE_CHAR_DELAY_MS)
+        }
+        delay(200)
+        while (typed.isNotEmpty()) {
+            typed = typed.dropLast(1)
+            setComposerText(typed)
+            delay(TYPE_CHAR_DELAY_MS)
+        }
+    }
+
+    /**
+     * Phase 4: [KEYBOARD_CYCLES] show/hide cycles through the same [WindowInsetsControllerCompat]
+     * path a real IME toggle goes through, reporting how many of each were actually confirmed by
+     * [android.view.WindowInsets.isVisible] rather than assumed from having asked -- UI_RULES:
+     * never present an inferred value as a measured one. If the platform never shows it even once,
+     * this says so in words rather than reporting a phase with no keyboard in it.
+     */
+    private suspend fun runKeyboardPhase(context: Context, view: View): String {
+        FrameStats.markPhase("keyboard")
+        var shown = 0
+        var hidden = 0
+        repeat(KEYBOARD_CYCLES) {
+            showIme(context, view)
+            delay(KEYBOARD_SHOW_WAIT_MS)
+            if (imeVisible(view)) shown++
+            hideIme(context, view)
+            delay(KEYBOARD_HIDE_WAIT_MS)
+            if (!imeVisible(view)) hidden++
+        }
+        return if (shown == 0) {
+            "  keyboard: could not be shown ($KEYBOARD_CYCLES attempts, 0 confirmed visible)"
+        } else {
+            "  keyboard: shown $shown/$KEYBOARD_CYCLES, hidden $hidden/$KEYBOARD_CYCLES" +
+                " (confirmed via isImeVisible)"
+        }
+    }
+
+    private fun controller(context: Context, view: View): WindowInsetsControllerCompat? {
+        val window = context.activity()?.window ?: return null
+        return WindowInsetsControllerCompat(window, view)
+    }
+
+    private fun showIme(context: Context, view: View) {
+        controller(context, view)?.show(WindowInsetsCompat.Type.ime())
+    }
+
+    private fun hideIme(context: Context, view: View) {
+        controller(context, view)?.hide(WindowInsetsCompat.Type.ime())
+    }
+
+    private fun imeVisible(view: View): Boolean =
+        ViewCompat.getRootWindowInsets(view)?.isVisible(WindowInsetsCompat.Type.ime()) ?: false
+
     /** VmHWM from /proc/self/status: the process's high-water mark, in kB, since it started. */
     private fun peakRssLine(): String {
         val kb =

app/androidApp/src/main/kotlin/com/example/aiapp/DebugStats.kt

@@ -134,6 +134,13 @@ fun debugReport(
      * render-report button reads exactly as it did before this existed.
      */
     extra: List<String> = emptyList(),
+    /**
+     * Bench v2's per-phase frame accounting ([FrameStats.phaseLines]) --
+     * fling/stream/type/keyboard, each a slice of the same frames the whole-run sections below
+     * still cover in full. Empty on every path but the scripted bench run, same reasoning as
+     * [extra].
+     */
+    phaseFrames: List<String> = emptyList(),
 ): String = buildString {
     appendLine("ai-app render report")
     appendLine(device)
@@ -148,6 +155,11 @@ fun debugReport(
     appendLine("transcript:")
     transcript.forEach { appendLine(it) }
     appendLine()
+    if (phaseFrames.isNotEmpty()) {
+        appendLine("per phase:")
+        phaseFrames.forEach { appendLine(it) }
+        appendLine()
+    }
     appendLine("frames:")
     frames.forEach { appendLine(it) }
     appendLine()

app/androidApp/src/main/kotlin/com/example/aiapp/FrameStats.kt

@@ -42,6 +42,21 @@ object FrameStats {
     private val gpu = ArrayList<Long>()
     private var since = System.currentTimeMillis()
 
+    /**
+     * Where a named phase of a scripted run (bench v2's fling/stream/type/keyboard) started, as an
+     * index into [total] and a wall-clock time -- not a second recorder, just a mark on this one,
+     * so a phase's frames are the same [FrameMetrics] the whole-run report already has, sliced.
+     */
+    private data class PhaseMark(val name: String, val startIndex: Int, val startMs: Long)
+
+    private val phaseMarks = ArrayList<PhaseMark>()
+
+    /** Call at the start of each named phase of a scripted run; see [BenchRun]. */
+    @Synchronized
+    fun markPhase(name: String) {
+        phaseMarks += PhaseMark(name, total.size, System.currentTimeMillis())
+    }
+
     @Synchronized
     fun add(metrics: FrameMetrics) {
         // The first frame after a window opens includes inflating it and is nobody's scroll.
@@ -69,6 +84,7 @@ object FrameStats {
         listOf(total, waited, input, animation, layout, draw, sync, issue, swap, gpu).forEach {
             it.clear()
         }
+        phaseMarks.clear()
         since = System.currentTimeMillis()
     }
 
@@ -95,6 +111,38 @@ object FrameStats {
         ) + if (gpu.isEmpty()) emptyList() else listOf(phase("gpu   ", gpu))
     }
 
+    /**
+     * One block per [markPhase] call: how many frames landed between that mark and the next (or the
+     * end of the run, for the last one), how many were late, the total/p50/p90/p99, the worst
+     * single frame, and how long the phase actually ran. Marks with no frames between them (a phase
+     * that finished before a frame was drawn) still get a line rather than being silently dropped
+     * -- UI_RULES' "say what you don't know" applies to a phase as much as to a single number.
+     */
+    @Synchronized
+    fun phaseLines(refreshHz: Float): List<String> {
+        if (phaseMarks.isEmpty()) return emptyList()
+        val budget = if (refreshHz > 0) 1000.0 / refreshHz else 16.7
+        val lines = ArrayList<String>()
+        phaseMarks.forEachIndexed { i, mark ->
+            val endIndex = if (i + 1 < phaseMarks.size) phaseMarks[i + 1].startIndex else total.size
+            val endMs =
+                if (i + 1 < phaseMarks.size) phaseMarks[i + 1].startMs
+                else System.currentTimeMillis()
+            val samples = total.subList(mark.startIndex, endIndex)
+            val seconds = (endMs - mark.startMs) / 1000.0
+            lines += "  ${mark.name}: ${samples.size} frames over ${"%.1f".format(seconds)}s"
+            if (samples.isEmpty()) {
+                lines += "    no frames recorded in this phase"
+            } else {
+                val late = samples.count { it / 1_000_000.0 > budget }
+                lines += "    late: $late (${percent(late, samples.size)})"
+                lines += "    " + phase("total ", samples)
+                lines += "    worst ${"%.1fms".format(samples.max() / 1_000_000.0)}"
+            }
+        }
+        return lines
+    }
+
     /** How long the frames recorded here spent in their draw phase, and how many there were. */
     @Synchronized fun drawPhase(): Pair<Long, Int> = draw.sum() to draw.size
 

app/androidApp/src/main/kotlin/com/example/aiapp/MainActivity.kt

@@ -187,13 +187,20 @@ class MainActivity : ComponentActivity() {
             model = null,
             keepsOwnTranscript = false,
             permissionMode = null,
+            effort = null,
+            takesEffort = false,
             imported = false,
             notify = false,
+            autoResume = false,
+            autoResumeMessage = "",
+            resumeAt = null,
             cwd = null,
             contextTokens = null,
             maxImageEdge = null,
+            usageProvider = null,
             status = "idle",
             lastActivity = 0.0,
+            subagents = 0,
         )
 
     // launchMode="singleTop": an enrollment scan, or a notification tapped while the app is open,

app/androidApp/src/main/kotlin/com/example/aiapp/SessionScreen.kt

@@ -12,6 +12,7 @@ import androidx.activity.result.PickVisualMediaRequest
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.foundation.background
 import androidx.compose.foundation.clickable
+import androidx.compose.foundation.gestures.ScrollableDefaults
 import androidx.compose.foundation.gestures.awaitEachGesture
 import androidx.compose.foundation.gestures.awaitFirstDown
 import androidx.compose.foundation.layout.Box
@@ -64,12 +65,15 @@ import androidx.compose.runtime.snapshots.Snapshot
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.drawWithContent
+import androidx.compose.ui.focus.FocusRequester
+import androidx.compose.ui.focus.focusRequester
 import androidx.compose.ui.graphics.graphicsLayer
 import androidx.compose.ui.input.pointer.PointerEventPass
 import androidx.compose.ui.input.pointer.pointerInput
 import androidx.compose.ui.layout.onSizeChanged
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.platform.LocalView
 import androidx.compose.ui.semantics.contentDescription
 import androidx.compose.ui.semantics.semantics
 import androidx.compose.ui.text.TextRange
@@ -354,6 +358,17 @@ fun SessionScreen(
     // `rememberSaveable`, and this screen restores by its own anchor instead -- two restores would
     // fight over the first frame.
     val listState = remember(address) { LazyListState() }
+    // The list's own fling path -- what a real flick decays through -- captured here so BenchRun's
+    // fling phase can drive `LazyListState.scroll` through exactly the `FlingBehavior` this
+    // screen's
+    // `TranscriptList` already uses by not overriding it (its `LazyColumn` takes no `flingBehavior`
+    // argument, so this is the same default it gets).
+    val flingBehavior = ScrollableDefaults.flingBehavior()
+    // Where BenchRun's type phase focuses before it types, and the view it toggles the keyboard on
+    // -- both bench-only, but cheap enough (a remembered object, a CompositionLocal read) to hold
+    // unconditionally rather than behind a second code path only the bench build compiles.
+    val composerFocus = remember { FocusRequester() }
+    val view = LocalView.current
     // Whether the newest message is on screen right now. The list is reversed, so the newest end is
     // the scrolling start: nothing behind you is exactly being at the bottom. Asked of the scroll
     // state rather than of item indices, because a zero-height first item makes an index ambiguous.
@@ -1256,6 +1271,10 @@ fun SessionScreen(
                     FrameStats.drawPhase().let { (nanos, count) -> drawAccounting(nanos, count) },
                 crash = lastCrash(context),
                 extra = extra,
+                // Empty outside a BenchRun.run pass -- copyRenderReport's own reset below clears
+                // the
+                // marks along with everything else, so an ordinary copy never has any to show.
+                phaseFrames = FrameStats.phaseLines(context.refreshHz()),
             )
         context.copyToClipboard("ai-app render report", report)
         // Also to the log, so a session driving the app over adb can read the same report the
@@ -1270,15 +1289,24 @@ fun SessionScreen(
         Toast.makeText(context, "Copied render report", Toast.LENGTH_SHORT).show()
     }
     val copyRenderReport = { buildAndCopyReport() }
-    // Bench build only: P0's scripted scroll-and-stream benchmark (BenchRun.kt), against the
+    // Bench build only: P0's scripted fling/stream/type/keyboard benchmark (BenchRun.kt), against
-    // fixture session opened below instead of a real server. Null everywhere else -- see
+    // the fixture session opened below instead of a real server. Null everywhere else -- see
     // [SessionSettingsDialog]'s onRunBenchmark.
     val runBenchmark: (() -> Unit)? =
         if (BuildConfig.FIXTURE_MODE) {
             {
                 settingsOpen = false
                 scope.launch {
-                    val extra = BenchRun.run(context, scope, listState)
+                    val extra =
+                        BenchRun.run(
+                            context = context,
+                            scope = scope,
+                            listState = listState,
+                            flingBehavior = flingBehavior,
+                            composerFocus = composerFocus,
+                            setComposerText = { text -> input = atEnd(text) },
+                            view = view,
+                        )
                     buildAndCopyReport(extra)
                 }
             }
@@ -1777,7 +1805,10 @@ fun SessionScreen(
                             input = it
                             saveDraft(context, summary.id, it.text)
                         },
-                        modifier = Modifier.fillMaxWidth(),
+                        // BenchRun's type phase requests focus on this exact field
+                        // (`composerFocus`)
+                        // so it types through the real composer rather than a stand-in.
+                        modifier = Modifier.fillMaxWidth().focusRequester(composerFocus),
                         // No longer "(+image)": the images are on screen above this, and a
                         // placeholder saying so said it in words beside the thing itself.
                         placeholder = { Text("Message") },

docs/RUST.md

@@ -4135,6 +4135,186 @@ device.
       back with a diagnostic that will say the real story on the next
       run either way.
 
+      **Benchmark v2 (2026-09-06), asked for by Iris after using the
+      Compose build on her phone**: "it doesn't fling like I typically do
+      when scrolling up to find old messages. It should travel way faster
+      which is better for stress testing. You may also want to add typing
+      in the textbox as well and seeing how performant wrapping & pushing
+      the transcript up are, and also keyboard performance if possible."
+      **This is the one spec** -- written once here so both apps' "Run
+      benchmark" implement the identical four phases; a change to a
+      constant below has to be made in both `app/`'s `BenchRun.kt` and
+      `iris/`'s bench client, together, or the two reports stop measuring
+      the same thing while still looking like they do.
+
+      1. **fling.** Starting pinned at the newest end
+         (`listState.scrollToItem(0)` / iris's equivalent), 8 flings away
+         from it (toward older messages) through the list's own real fling
+         path -- Compose: `LazyListState.scroll { with(flingBehavior) {
+         performFling(velocity) } }` using the screen's actual
+         `FlingBehavior` (`ScrollableDefaults.flingBehavior()`, since
+         `TranscriptList`'s `LazyColumn` never overrides it -- **not**
+         `animateScrollBy`, which can only ever cover the fixed distance
+         and time it is given and was Iris's complaint) -- each fling's
+         `initialVelocity = 12,000 px/s`. That number is well above a
+         moderate tween-swipe's implied speed (v1's `SWIPE_PX`/`SWIPE_MS`
+         is roughly 4,500 px/s) and is meant to be a hard, fast flick for
+         stress-testing, per Iris's ask. After each fling, wait for
+         `isScrollInProgress` to clear (cap 3s; `performFling` already
+         suspends until its own decay ends, this is belt-and-suspenders)
+         plus 300ms between flings. Then 8 more flings back toward the
+         newest end (`-12,000 px/s`). Record the list's first visible
+         index/offset at the start, after the 8 outward flings, and at the
+         end, so the two apps' *travel* can be compared directly rather
+         than just their frame times.
+      2. **stream. Unchanged from v1**: 400 tail events at 20/s (20
+         seconds), pinned to the newest end before it starts (the same
+         "Jump to latest" pin `stream-bench.sh` does).
+      3. **type.** Pin to the newest end, focus the composer, show the IME
+         if the platform allows it, then insert this **exact 600-character
+         string** one character per 50ms through the composer's real
+         `TextFieldValue` state (Compose: the same `input` state
+         `onValueChange` writes; iris: whatever holds the composer's text
+         today), then delete it the same way, one character per 50ms.
+         Chosen for long, multisyllabic words specifically so the composer
+         wraps across lines and the transcript above it is pushed upward
+         by a growing box, which is what Iris asked to see measured:
+
+             Benchmarking this transcript screen requires unusually long, multisyllabic words so wrapping and reflow are properly exercised: internationalization, counterproductiveness, disproportionately, incomprehensibility, deinstitutionalization, uncharacteristically, overenthusiastically, misunderstanding, straightforwardness, telecommunications, and interdisciplinary collaboration all push a narrow composer field to wrap across several lines while the transcript above is pushed upward by the growing keyboard-adjacent box, which is exactly what a real reader typing a long message sees happening now!!!
+
+         Report whether the IME was actually open during typing (it should
+         be, from this phase's own show-IME step -- see phase 4 for what
+         to say if the platform refuses to show it at all).
+      4. **keyboard.** Show the IME (`WindowInsetsControllerCompat.show
+         (WindowInsetsCompat.Type.ime())` against the window/view; iris's
+         equivalent through its own shell), wait 1s, hide it, wait 1s;
+         five cycles. Confirm each show/hide with the platform's own
+         answer (Compose: `ViewCompat.getRootWindowInsets(view)
+         ?.isVisible(WindowInsetsCompat.Type.ime())`, i.e. the same
+         `WindowInsets.isImeVisible` fact `SessionScreen`'s composer-inset
+         bug fix already relies on) rather than assuming the request
+         worked -- if it is never confirmed shown even once, the report's
+         `keyboard:` line has to say "**keyboard: could not be shown**"
+         in words (UI_RULES: never present an inferred value as a
+         measured one, and design the unknown/failed state before the
+         answer's).
+
+      **Frame accounting**: one recorder, not two. Mark each phase's start
+      in the existing per-frame recorder (Compose: `FrameStats.markPhase
+      (name)`, a list of `(name, frameIndexAtStart, wallClockAtStart)`
+      alongside the existing `total`/`waited`/... arrays) and slice the
+      same `FrameMetrics` samples by phase afterward
+      (`FrameStats.phaseLines`) rather than running a second listener.
+
+      **Report shape**: a `per phase:` block appears once any phase marks
+      exist (empty/absent on an ordinary "Copy" press, which never marks a
+      phase), one entry per phase: frame count, the phase's wall-clock
+      duration, late count/percent (against the same refresh-rate budget
+      the whole-run section uses), p50/p90/p99, and the worst single
+      frame. Then **every existing whole-run section stays, unchanged in
+      shape** -- `frames:`, `where the draw phase went:`, `work since this
+      was last copied:` -- because that is what the emulator-baseline and
+      phone-baseline numbers already on record in this file were read
+      against, and a report that dropped or renamed one of those lines
+      would silently stop being comparable to them. Finally `bench:` gains
+      new lines beside the existing CPU/RSS/battery ones: the fling
+      phase's total travel (start/outward/end index+offset), the typed
+      character count, and the keyboard phase's shown/hidden-confirmed
+      counts (or the "could not be shown" line).
+
+      **Compose half: done, 2026-09-06.** `FrameStats.markPhase`/
+      `phaseLines` (`app/androidApp/src/main/kotlin/com/example/aiapp/
+      FrameStats.kt`), `debugReport`'s new `phaseFrames` parameter
+      (`DebugStats.kt`), and `BenchRun.kt`'s four-phase `run` (fling via
+      `ScrollableDefaults.flingBehavior()` captured in `SessionScreen` and
+      passed down since it needs a `@Composable` call site; type via a new
+      `composerFocus: FocusRequester` attached to the composer's
+      `OutlinedTextField` plus a `setComposerText` callback that writes
+      `input` the same way a keystroke does; keyboard via
+      `WindowInsetsControllerCompat` against `LocalView.current`) are all
+      in. `BenchRun.TYPE_TEXT` is the exact 600-character constant quoted
+      above (verified `.length == 600`). A pre-existing, unrelated break
+      in `MainActivity.kt`'s `benchSessionSummary()` (missing several
+      `SessionSummary` constructor arguments added by a change this pass
+      did not otherwise touch -- confirmed pre-existing by reproducing the
+      same compile failure after stashing this pass's own diff) was fixed
+      alongside this, since it blocked `compileBenchKotlin` outright and
+      is in this session's own `app/` scope.
+
+      Checks all clean: `ktfmtFormat`, `compileDebugKotlin`,
+      `compileBenchKotlin`, `lintDebug`, `lintBench` (both "No issues
+      found"), `testDebugUnitTest`. `grep -n "tap [0-9]" app/*.sh` still
+      has its one pre-existing, unrelated hit.
+
+      **Compose bench v2, emulator smoke run, 2026-09-05** (this
+      checkout's AVD, cold `emu up`, `ui-trace` tap-by-label throughout --
+      the dialog needed a swipe to reach "Run benchmark" below the fold,
+      report read back over `adb logcat`):
+
+          ai-app render report
+          device: sdk_gphone64_x86_64 (Google), Android 16
+          build: release
+
+          transcript:
+            124 events, 26 rows, 58 units loaded
+            viewport 1714px, 2 units visible
+            on screen: the list's own 0px, AssistantMsg 18732px
+            0 tool calls and 0 groups open
+
+          per phase:
+            fling: 1620 frames over 32.3s
+              late: 1537 (94.9%)
+                total  p50 20.5ms  p90 29.2ms  p99 45.9ms
+              worst 61.8ms
+            stream: 1079 frames over 20.6s
+              late: 1037 (96.1%)
+                total  p50 21.0ms  p90 33.5ms  p99 39.3ms
+              worst 51.2ms
+            type: 3568 frames over 61.4s
+              late: 3536 (99.1%)
+                total  p50 23.8ms  p90 32.1ms  p99 38.5ms
+              worst 50.3ms
+            keyboard: 215 frames over 10.0s
+              late: 212 (98.6%)
+                total  p50 21.3ms  p90 37.6ms  p99 48.4ms
+              worst 50.2ms
+
+          frames:
+            6482 frames over 124.3s at 60Hz (16.7ms budget)
+            late: 6322 (97.5%)
+            total  p50 21.7ms  p90 33.1ms  p99 45.3ms
+            gpu    p50 17.4ms  p90 27.0ms  p99 30.6ms
+
+          where the draw phase went:
+            draw phase 1.27ms per frame, of which:
+              the transcript: 0.16ms (measure 0.09, place 0.07, record 0.00)
+              everything else: 1.10ms (87%)
+
+          bench:
+            fling: 8 flings out + 8 back at 12000px/s, travel start=idx=0/off=0px outward=idx=218/off=73px end=idx=0/off=0px
+            scroll: 6 cycles (24 swipes, legacy tween), streamed 400/400 fixture events
+            type: 600 characters inserted then deleted, one per 50ms
+            keyboard: shown 5/5, hidden 5/5 (confirmed via isImeVisible)
+            process CPU time over this run: 61192ms
+            peak RSS: 195716kB
+            battery current: mean 900000µA over 125 samples (min 900000, max 900000)
+
+      Read this the same way the v1 emulator smoke run above is read: it
+      proves the harness runs end to end and produces every field this
+      spec asked for, not a phone number -- software rasterisation, and
+      the fixed 900mA battery reading is the emulator's mocked charger
+      again. Two things worth carrying forward: the **fling phase reached
+      index 218** in 8 flings (against v1's `animateScrollBy` loop, which
+      never moved past a handful of indices in the same 8-swipe count),
+      which is the direct evidence the new fling travels "way faster" as
+      asked; and **the emulator's software keyboard toggled and was
+      confirmed by `isImeVisible` all 10 times**, so phase 4 is not a
+      guaranteed "could not be shown" on every platform, only where the
+      IME genuinely refuses. `frames:`'s 6,482-frame, 124.3s total matches
+      the sum of the four phase durations (32.3+20.6+61.4+10.0 ≈ 124.3s),
+      confirming the phase marks partition the whole run rather than
+      overlapping or dropping frames between them.
+
 - [ ] **P1 — session screen parity.** History paging backward (with the
       page-boundary healing `client-core` does not have yet, below),
       `TranscriptSource`-backed cache/server stitching, jump-to-latest,