feat(core): render HTML artifacts inline without a remote container

[zebster-cmd]

What

Renders AI HTML artifacts locally instead of loading the remote page https://affine.run/static/container.html and posting the HTML into it.

That remote page was the isolation boundary — it ran artifact scripts on a foreign origin. The cost was a hard runtime dependency on affine.run for what is otherwise a purely local render, which means blank previews on a self-hosted deploy, offline, or on any network hiccup.

How

• Local srcdoc replaces the remote src + cross-window postMessage handshake.
• Sandbox grants allow-scripts but deliberately omits allow-same-origin. The frame gets an opaque origin, so artifacts stay interactive while losing all access to the host document, storage, cookies, and auth. This is stricter than what it replaces — the old flow ran with allow-same-origin, and the remote container performed no origin check on incoming messages.
• Injected bootstrap reports content height / readiness / errors over postMessage. The host authenticates by window handle (event.source === iframe.contentWindow), because an opaque guest must post with a wildcard target and the marker alone is guessable.
• Sizing gated behind a new autoResize prop. The chat preview panel stretches the frame to height:100% via CSS, so writing an inline height there would override that rule and break the panel — code-artifact.ts passes autoResize=false. Doc-inline previews size to content, clamped to 640px, replacing the hard-coded 544px.
• Artifact state now survives the Code/Preview toggle. The old code swapped between two different lit templates, which tore down the iframe every toggle. Both views now stay mounted, toggled with [hidden] and keyed by toolCallId.

Verification

Unit + real-Chromium integration (artifact-sandbox.integration.spec.ts), 74 new tests:

• Scripts run, forms accept input, zero network requests
• window.origin is 'null'; guest cannot reach parent.document, host localStorage, or cookies
• State survives a hidden toggle; resets on re-creation (the old behaviour, kept as a test)
• A dedicated group adds allow-same-origin in the test only to prove that flag is what would collapse the boundary; a third test asserts production never grants it

Checked on this branch:

Check	Result
blocksuite specs	162 passed
yarn affine @affine/web build	exit 0 (clean rebuild)
Shipped bundle contains affine.run/static/container	absent
Shipped bundle contains affine-artifact bootstrap	present
tsc -b	2 pre-existing Electron-only errors (@affine/auth .d.ts not built locally); no Electron job in the self-host image

Notably, the browser enforces this harder than specified: Chromium throws SecurityError on document.cookie in the guest rather than returning empty.

Deploy impact

Merging this updates requesty-provider-spec, which triggers requesty-selfhost-image.yml → pushes ghcr.io/zebster-cmd/affine:requesty for Coolify to redeploy.

Known limitations

• Not verified in the assembled app. Both call sites (chat artifact panel, doc affine:code preview block) are verified at the renderer level, not by driving a running AFFiNE instance with a live AI response.
• Rust/Docker build not validated locally — this change is frontend-only and touches no Rust, but "web build passes" is not "image builds".
• Artifacts relying on localStorage will now throw instead of silently working, since the guest is on an opaque origin. Judged acceptable for one-shot generated artifacts.

Planning artifacts: openspec/changes/add-inline-html-renderer/

🤖 Generated with Claude Code