devisland-markdown-rendering

name	devisland-markdown-rendering
description	Change DevIsland MarkdownView, agent message rendering, hook message formatting, diff rendering, attachment loading, heading handling, link/image safety, or tool output presentation. Use for MarkdownView, ToolMessageFormatter, Notch UI message displays, and related rendering tests.

DevIsland Markdown Rendering

Use this for message rendering and diff display changes. Pair with devisland-notch-ui when the rendered content appears in the notch or expanded panel.

Start

Read AGENTS.md and inspect existing behavior in:

• DevIsland/UI/MarkdownView.swift
• DevIsland/Provider/ToolMessageFormatter.swift
• DevIsland/UI/NotchView.swift
• DevIsland/UI/NotchComponents.swift
• DevIsland/UI/PluginContributionRenderer.swift when plugin contribution text is involved
• DevIslandTests/ToolMessageFormatterTests.swift

Check recent tests before changing parsing or formatting.

Rendering Rules

Preserve scalar hook message formatting. Do not flatten whitespace-only edits or meaningful line breaks.

For diff rendering:

• Preserve whitespace-only changes.
• Keep edit/replace labels visually distinct.
• Guard empty or malformed patches.
• Avoid crashes on invalid heading levels or malformed Markdown.

For security:

• Do not load remote images unexpectedly.
• Do not open links without explicit user intent.
• Treat command output and tool responses as untrusted display content.
• HTML previews go through HTMLPreviewContentPolicy (size limits, document wrapping) — keep it restrictive and covered by HTMLPreviewContentPolicyTests.

UI Fit

Rendered text must fit in compact panels and session lists. Avoid hero-scale type inside notch surfaces. Keep headings smaller and predictable inside compact UI.

If changing font size, weight, or spacing, verify readability in both collapsed/expanded contexts and session lists.

Tests And Checks

Use focused tests for formatter behavior:

• ToolMessageFormatterTests
• PluginContributionRendererTests when plugin UI text rendering changes
• Any MarkdownView or message rendering tests present in the repo

Run:

./scripts/run-tests.sh
./scripts/build_and_run.sh --no-kill --no-run

For visual-only changes, describe the manual rendering cases to inspect.