Rendering attribution evidence

Capture

Fixture: disposable Chromium E2E task with one active task and one Quick Chat task, both running the slow mock command.
Runner: Chromium project, one shard and one worker, Playwright 1.61.1.
Host capacity: 11 logical CPUs were visible to the runner. The capture does not use a fixed CPU percentage gate.
Protocol: one second settle, then three 8.34-second windows per repeated arm.

Command:

(cd apps/web && KANDEV_E2E_ANIMATION_TRACE=1 \
  KANDEV_E2E_ANIMATION_TRACE_REPEATS=3 \
  rtk pnpm e2e:run --project chromium \
  tests/chat/animation-performance-trace.spec.ts)

The trace test records event counts and summed event durations. Nested trace events are not added as a CPU total.

Target inventory

The normal-page inventory found the host-owned targets used by the isolation arms:

.spinner-grid-cube: 18 visible CSS/animation targets in the fixture.
[data-testid=chat-input-glow].chat-input-glow-running: the active composer pulse target.
CSS fallback keyframes: spinner-grid and chat-input-glow-pulse.
Other transient inventory entries included sidebar fade/collapse and dialog enter animations. No node-level target from the supplied trace was added to the production repair list.

The inventory also inspects ::before and ::after computed styles and the document Web Animations list. It is diagnostic only and is not used to pause arbitrary application animations in production.

Three-run summaries

Values are shown as median with the observed minimum and maximum in brackets. Target invalidations are counts of matching invalidation events.

Arm	UpdateLayoutTree count	Layerize count	Target invalidations	Grid / pulse invalidations
Normal page	6 [0, 6]	3 [0, 3]	76 [0, 114]	72 [0, 108] / 4 [0, 6]
CSS fallback control	272 [235, 272]	239 [218, 244]	5,168 [4,465, 5,168]	4,896 [4,230, 4,896] / 272 [235, 272]
Grid paused	297 [289, 334]	279 [275, 303]	297 [289, 334]	0 / 297 [289, 334]
Pulse paused	32 [31, 33]	30 [29, 33]	576 [558, 594]	576 [558, 594] / 0
All motion paused	1 [0, 1]	1 [0, 1]	0 [0, 0]	0 / 0

The script-disabled compositor control recorded zero target invalidations. The normal-page trace includes a zero-event first window, which is retained in the range rather than discarded. CSS fallback target animations were verified as running before and after every isolation arm.

Attribution result

The isolation control is working: pausing the grid removes grid invalidations, pausing the pulse removes pulse invalidations, and pausing all motion removes the matched invalidation stream. This attributes the fixture's own fallback work to those two targets.

It does not attribute the supplied 5.57-second production trace's persistent Layerize work. That trace lacks node-level style invalidation and already running-animation attribution, and the small disposable fixture does not reproduce its continuous Layerize cadence. Task 03 therefore remains pending; no speculative production repair was made.

The separate confirmed context-ring issue remains bounded to its short value transition. Task 02 addresses that contract independently.

Post-integration verification

An earlier post-integration run on 2026-09-10 recorded normal-page medians of 14 UpdateLayoutTree events, 12 Layerize events, and 228 matched target invalidations. That run was retained as historical evidence; the controls were subsequently hardened to keep targets alive and compare each paused group with the matched script-enabled fallback baseline.

Review-remediation verification

The three-repeat Chromium command passed on 2026-09-11 after the visibility and trace-control remediation. Every arm retained 18 grid targets and one pulse target. The normal compositor arm recorded zero target invalidations in all three windows. The disabled-script CSS-fallback control recorded 646 target invalidations at the median [608, 703], split into 612 grid [576, 666] and 34 pulse [32, 37]. The matched script-enabled CSS-fallback baseline recorded 665 target invalidations [627, 703], split into 630 grid [594, 666] and 35 pulse [33, 37].

Arm	Target invalidations	Grid / pulse invalidations
CSS fallback baseline	665 [627, 703]	630 [594, 666] / 35 [33, 37]
Grid paused	12 [11, 17]	0 / 12 [11, 17]
Pulse paused	468 [414, 504]	468 [414, 504] / 0
All motion paused	0 [0, 180]	0 [0, 180] / 0

The paused group is suppressed against its matched script-enabled baseline in each selective arm. The unpaused group remains active: pulse invalidations continue in the grid-paused arm, and grid invalidations continue in the pulse-paused arm. Residual invalidations in one all-motion window are retained in the range rather than treated as a strict-zero gate; its median remains below both baseline group medians. This verifies the bounded attribution control without identifying the supplied trace's production rendering trigger.

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