Txt Apple Docs

Apple Documentation Lookup

Authored against iOS 26.x / Swift 6.x / Xcode 26.x.

This skill is the documentation pipe for the Apple Text skill set. Apple's developer.apple.com pages are JS-rendered and return a "needs JavaScript" stub to non-browser fetches, so the practical access paths are Sosumi (a clean Markdown mirror at sosumi.ai plus an MCP server at https://sosumi.ai/mcp) and Apple's own xcrun mcpbridge (Xcode 26.3+, on-machine Xcode-bundled docs and indexed WWDC transcripts). Before claiming any specific API signature, behavior, deprecation status, or available-since version, fetch the current Apple docs through one of these tools — Apple ships fast and training cutoffs lag, so a memorized signature is the most common source of confidently-wrong code in this domain.

Contents

• Sosumi: URL swap and MCP
• xcrun mcpbridge
• When to use which
• Local sidecar references
• Configuration
• References

Sosumi: URL swap and MCP

sosumi.ai mirrors Apple's developer documentation under the same path structure as developer.apple.com. The URL swap is one-to-one — every Apple docs URL has a Sosumi equivalent.

developer.apple.com/documentation/uikit/uitextview
        ↓
sosumi.ai/documentation/uikit/uitextview

The Sosumi page returns clean Markdown that any agent can read directly. This is the format used in every cross-reference link inside Apple Text skill content; the markdown stays portable to any client that can read URLs.

The Sosumi MCP server lives at https://sosumi.ai/mcp (Streamable HTTP + SSE) and exposes two tools:

• search_documentation — keyword search across Apple's documentation index, returns ranked candidate URLs.
• fetch_documentation — pull the Markdown body of a specific page given its URL or symbol path.

When connected via MCP, prefer search_documentation for "what's the right API for X" questions and fetch_documentation for "give me the current signature of Y" questions. Both are stateless and cheap — call them freely rather than guessing from memory.

Verifying a URL before publishing it in skill content:

curl -s -o /dev/null -w "%{http_code}\n" "https://sosumi.ai/documentation/uikit/uitextview"
# 200 = good. 404 = path doesn't resolve, find a working alternative or omit the link.

Apple sometimes reorganizes documentation paths between Xcode releases. A 404 doesn't mean the API is gone; it means the path moved. Search via sosumi.ai or via the MCP search_documentation tool to find the new location.

xcrun mcpbridge

Xcode 26.3 (Feb 2026) shipped xcrun mcpbridge, an MCP server that exposes Xcode's bundled documentation and indexed WWDC transcripts to external agents. It's an Apple-controlled fallback for cases where Sosumi 404s, the network is unavailable, or you need WWDC-session content that Sosumi doesn't index.

The bridge launches as a subprocess and speaks MCP over stdio:

xcrun mcpbridge

Among its 20-tool catalog, the relevant ones for documentation are:

• DocumentationSearch — keyword search against the docs bundled with the local Xcode install.
• WWDCTranscriptSearch — keyword search against indexed WWDC session transcripts.

These return on-machine content that matches the Xcode version installed. If the local Xcode is 26.3, DocumentationSearch returns the docs Apple shipped with 26.3 — which may differ from sosumi.ai's mirror if the mirror is a release behind. For verification work, the bridge is the closer-to-source channel; for portable skill content, Sosumi URLs are the right link target.

Skill content should always link to sosumi.ai URLs (so the markdown is portable to clients without xcrun mcpbridge available). Use the bridge as a runtime verification tool, not as a link target in committed content.

When to use which

Three practical cases:

• You're writing or editing a skill and need to add a documentation link. Use Sosumi via URL swap. Verify with curl that the URL returns 200 before committing.
• You're answering a live question and need to confirm an exact API signature. Use the Sosumi MCP server (fetch_documentation on the symbol page) if connected, or xcrun mcpbridge's DocumentationSearch if the agent runs locally with Xcode 26.3+ available.
• You need WWDC-session content for a "what changed" question. xcrun mcpbridge's WWDCTranscriptSearch is the right path — Sosumi indexes the documentation but not the session transcripts.

Neither path is a substitute for opening the actual project source. Documentation tells you what the API does; the project source tells you what's already calling it. Skills that diagnose code (txt-textkit-debug, txt-fallback-triggers) ground their patterns in source code first, then verify API claims against docs second.

Local sidecar references

This skill carries a small set of pre-fetched Apple-text-relevant doc summaries as repo sidecars, useful as an offline fallback and as quick context when no MCP server is connected:

• references/xcode-docs-index.md — index of the Apple-text subset and the bundled Swift diagnostics catalog.
• references/xcode-attributedstring-updates.md — Foundation AttributedString surface changes.
• references/xcode-styled-text-editing.md — SwiftUI styled TextEditor editing behavior.
• references/xcode-toolbar-features.md — toolbar features near editing and text-centric UI.

These sidecars are time-stamped against the Xcode version that produced them. Treat them as snapshots: useful for context when MCP is unavailable, but recheck against Sosumi or xcrun mcpbridge before quoting a signature into production code.

Configuration

Two environment variables control the runtime Apple-doc reading behavior used by other Apple Text skills:

When APPLE_TEXT_APPLE_DOCS=true and a local Xcode contains the for-LLM Markdown bundle, prefer it for verification. The repo sidecars in references/ are the offline fallback when the runtime channel is unavailable.

References

• /skill txt-attributed-string — AttributedString decisions and conversions
• /skill txt-swiftui-texteditor — SwiftUI rich-text editing on iOS 26+
• /skill txt-writing-tools — Writing Tools integration (time-sensitive surface)
• /skill txt-detectors-tagger — Foundation/NaturalLanguage utilities
• Sosumi.ai — Markdown mirror of Apple developer docs
• Giving external agents access to Xcode — xcrun mcpbridge overview