Track WinUI ItemsView fix and retire Reactor preview.12 Markdown workaround

[karkarl]

Context

Temporarily pin Microsoft.UI.Reactor and Microsoft.UI.Reactor.Advanced to 0.1.0-preview.12 to mitigate the release-blocking chat session-switch crashes reported in #1421 and #1419. The identified trigger is the ElementFactory eviction/lifetime change introduced in preview.13: microsoft/microsoft-ui-reactor@8ee940c. The underlying WinUI defect is microsoft/microsoft-ui-xaml#11865: ItemsView retains a pending bring-into-view target after that target is collapsed, leading to E_INVALIDARG.

This reverses the dependency upgrades in #1376 (build(deps): upgrade Microsoft.UI.Reactor to 0.1.0-preview.14) and #1400 (fix(chat): prevent bubble text truncation), not unrelated improvements in those PRs.

Why this workaround

#1407 (fix(chat): work around WinUI session-switch crash) avoided the crash in reported tests, but Barbara's 240 mixed-height message scenario stopped near message 233. The bottom extent changes as virtualized rows render, so scrolling to the current extent does not guarantee reaching the final message. That is also a release blocker. Preserve the existing row-targeted scrolling rather than adopting that workaround.

Preview.15 included microsoft/microsoft-ui-reactor#1197 (Fix Markdown list content wrapping). While pinned to preview.12, use the public MarkdownOptions.ListItem callback to replace the default horizontal list-row stack with an Auto-marker/Star-content Grid. Preserve the parser-produced marker, content, spacing, nesting and inline formatting rather than flattening Markdown or imposing fixed widths.

Retirement gates

• Track ItemsView crashes with E_INVALIDARG when a pending bring-into-view target is collapsed microsoft/microsoft-ui-xaml#11865 through a released Windows App SDK NuGet containing the fix (not merely a source merge).
• Select and test a compatible Reactor version containing Fix Markdown list content wrapping microsoft/microsoft-ui-reactor#1197 and the corrected ItemsView lifetime behavior.
• Update both Reactor packages together and remove the preview.12 pin and local ListItem layout override in the same PR.
• Retain behavioral regression coverage for ordered/unordered, nested, loose, formatted and long list content at narrow widths and after resize.
• Prove repeated session switching while bring-into-view is pending, history replacement, and 240 mixed-height messages. Verify the actual final message is visible, not merely the current scroll extent.
• Verify streaming tail-follow and preservation of the reader's position when scrolled up.
• Run the full repository build, Shared and Tray tests, and current-head mounted WinUI proof. Record exact package versions and results.

Until these gates pass, do not remove the compatibility workaround or automatically advance Reactor past preview.12.

[clawsweeper]

Codex review: keeping this open for maintainer follow-up; there is still a little grit to resolve. Reviewed September 14, 2026, 9:44 PM ET / September 15, 2026, 01:44 UTC.

Summary
Keep this collaborator-authored retirement tracker open. Its gates remain outstanding: current main and the latest release still use preview.15, the proposed compatibility workaround is absent from main, and the upstream WinUI issue remains open.

Reproducibility: not applicable. to this retirement tracker. The linked upstream report supplies a concrete native crash reproducer, but no current-main runtime reproduction was executed in this read-only review.

Ways to help us reproduce this

• Add a screenshot or short recording showing the behavior.
• Add expected vs actual behavior.

Next step
Preserve the existing retirement gates and revisit after upstream release evidence is available; an automatic repair would prematurely choose dependency versions.

Review details

Best possible solution:

Retire the compatibility layer atomically with a verified package pair only after mounted WinUI coverage establishes list layout, lifecycle safety, final-message visibility, and reader-position preservation.

Do we have a high-confidence way to reproduce the issue?

Not applicable to this retirement tracker. The linked upstream report supplies a concrete native crash reproducer, but no current-main runtime reproduction was executed in this read-only review.

Is this the best way to solve the issue?

Yes. Waiting for a released dependency fix and testing the complete scrolling and Markdown contract is appropriate; the existing preview.15 selection is not evidence that retirement is complete.

AGENTS.md: found and applied where relevant.

Remaining risk / open question:

• A released Windows App SDK containing the lifetime repair and a compatible Reactor combination have not been established.
• Successful Markdown wrapping alone does not establish safe session switching, final-message visibility, streaming follow, or preservation of the reader’s position.

Codex review notes: model internal, reasoning medium; reviewed against ddb54a9614a5.

Label changes

Label changes:

• add P2: This is a dependency-gated retirement tracker; immediate user crash remediation is already tracked separately.
• add impact:crash-loop: The retirement gates prevent native chat layout failures from terminating Companion during session changes.
• add issue-rating: 🌊 off-meta tidepool: Current issue advisory state selects this label.
• remove P1: Current review triage priority is P2, so this older priority label is no longer current.

Label justifications:

• P2: This is a dependency-gated retirement tracker; immediate user crash remediation is already tracked separately.
• impact:crash-loop: The retirement gates prevent native chat layout failures from terminating Companion during session changes.

Evidence reviewed

What I checked:

• Current main has not adopted the temporary workaround: Checkout HEAD matches the supplied main SHA. Both Reactor packages remain at 0.1.0-preview.15; the production Markdown options contain no ListItem override. A search of src, tests, and docs found no preview.12 pin or ListItem assignment. (src/OpenClaw.Tray.WinUI/OpenClaw.Tray.WinUI.csproj:97, ddb54a9614a5)
• Production dependency boundary: The scrolling owner imports Reactor and WinUI and calls ItemsView.StartBringItemIntoView after validating the current tail identity. BuildSafeMarkdown calls Reactor.Advanced.Factories.Markdown. These direct dependencies establish why the upstream WinUI and Reactor contracts matter. (src/OpenClaw.Tray.WinUI/Chat/ReactorItemsViewScrollController.cs:269, ddb54a9614a5)
• Upstream lifetime defect remains open: ItemsView crashes with E_INVALIDARG when a pending bring-into-view target is collapsed microsoft/microsoft-ui-xaml#11865 remains open. Its report documents a pending bring-into-view target becoming collapsed during Reactor recycling and reaching native anchor validation; its comments do not identify a released fix.
• Markdown repair is separate from lifetime repair: Fix Markdown list content wrapping microsoft/microsoft-ui-reactor#1197 (Fix Markdown list content wrapping) is merged. It changes default list rows to Auto/Star Grid layout and explicitly separates consumer adoption and workaround removal from the upstream repair; it does not establish the ItemsView retirement gate. (323b7d75b138)
• Latest shipped package selection: GitHub reports v2026.9.3 as the latest release. Its project file pins both Reactor packages to preview.15, so that release does not demonstrate the requested retirement sequence. (src/OpenClaw.Tray.WinUI/OpenClaw.Tray.WinUI.csproj:85, 84928c4370bc)
• Related workaround does not own retirement: The open PR list includes fix(chat): work around WinUI session-switch crash #1407 (fix(chat): work around WinUI session-switch crash). Its supplied body describes ScrollTo mitigation and limited 77-message proof; this issue records the separate 240-message failure and explicitly preserves row-targeted navigation. No listed open PR implements the package-pin retirement.

Likely related people:

• karkarl: Suggested for follow-up; no historical authorship or introduction is verified. (role: unverified routing candidate; confidence: low)
• azchohfi: Suggested for follow-up; no historical authorship or introduction is verified. (role: unverified routing candidate; confidence: low)

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