imla-scene-counters

name	imla_scene_counters
description	Read Imla scene renderer counters from repo-local Perfetto analysis. Use when evaluating render reasons, root captures, slot content captures, mask/clip captures, geometry refreshes, scene renders, or whether an interaction is content-capture-heavy versus geometry-only.

Imla Scene Counters

Use this skill after capturing an Imla trace with tools/imla-perfetto-feedback.

Counter Output

The primary generated file is:

diagnostics/apa/traces/<trace>.perfetto-trace_analysis/60_scene_counters.txt

If it is empty, either the trace did not include scene-counter events or the app did not execute the scene path during the captured window.

Important Counters

• ImlaScene/root.capture.commit: committed root clean plate captures.
• ImlaScene/frame.commit.total: committed scene frames.
• ImlaScene/geometry.refresh: geometry-only scene refresh attempts that produced a frame.
• ImlaScene/render.request.*: render requests by reason.
• ImlaScene/render.consume.*: reasons consumed by actual GL renders.
• ImlaScene/render.total: scene GL renders.
• ImlaScene/slot.content.capture: foreground slot content captures.
• ImlaScene/slot.mask.capture: blur mask captures.
• ImlaScene/slot.clip.capture: clip mask captures.
• ImlaScene/render.slot.composite: slots composited by the GL scene renderer.
• ImlaScene/render.backdrop.composite: backdrop blur composite passes.
• ImlaScene/render.content.composite: foreground content composite passes.
• ImlaScene/render.stencil.setup: stencil clip setup passes.

max_value is the cumulative app-session counter value observed during the trace. observed_delta is the difference between the first and last observed values inside the trace window.

Reading A Trace

For idle validation:

render.total should be low.
slot.content.capture should not climb continuously.
root.capture.commit should not climb continuously.

For bottom sheet or placement motion:

geometry.refresh should increase.
slot.content.capture and slot.mask.capture should stay flat or grow much more slowly.
render.consume.SlotChanged should correspond to actual scene renders.

For content/style changes:

slot.content.capture may increase for content changes.
slot.mask.capture or slot.clip.capture may increase for mask/clip changes.
render.backdrop.composite and render.content.composite show GL pass volume.

Workflow

1. Capture idle and interaction traces:

tools/imla-perfetto-feedback capture --device <serial> --no-exercise
tools/imla-perfetto-feedback smoke --device <serial>

2. Open 60_scene_counters.txt and compare counters between traces.
3. Cross-check 50_renderer_trace_anchors.txt for slice timing and count details.
4. Use screenshot diff only after a rendering behavior change; counters do not prove visual correctness.