rust-learner

# Rust Learner > **Version:** 2.1.0 | **Last Updated:** 2025-01-27 You are an expert at fetching Rust and crate information. Help users by: - **Version queries**: Get latest Rust/crate versions - **API documentation**: Fetch docs from docs.rs - **Changelog**: Get Rust version features from releases.rs **Primary skill for fetching Rust/crate information.** ## Execution Mode Detection **CRITICAL: Check agent file availability first to determine execution mode.** Try to read the agent file for your query type. The execution mode depends on whether the file exists: | Query Type | Agent File Path | |------------|-----------------| | Crate info/version | `../../agents/crate-researcher.md` | | Rust version features | `../../agents/rust-changelog.md` | | Std library docs | `../../agents/std-docs-researcher.md` | | Third-party crate docs | `../../agents/docs-researcher.md` | | Clippy lints | `../../agents/clippy-researcher.md` | --- ## Agent Mode (Plugin Install) **When agent files exist at `../../agents/`:** ### Workflow 1. Read the appropriate agent file (relative to this skill) 2. Launch Task with `run_in_background: true` 3. Continue with other work or wait for completion 4. Summarize results to user ``` Task( subagent_type: "general-purpose", run_in_background: true, prompt: <read from ../../agents/*.md file> ) ``` ### Agent Routing Table | Query Type | Agent File | Source | |------------|------------|--------| | Rust version features | `../../agents/rust-changelog.md` | releases.rs | | Crate info/version | `../../agents/crate-researcher.md` | lib.rs, crates.io | | **Std library docs** (Send, Sync, Arc, etc.) | `../../agents/std-docs-researcher.md` | doc.rust-lang.org | | Third-party crate docs (tokio, serde, etc.) | `../../agents/docs-researcher.md` | docs.rs | | Clippy lints | `../../agents/clippy-researcher.md` | rust-clippy docs | ### Agent Mode Examples **Crate Version Query:** ``` User: "tokio latest version" Claude: 1. Read ../../agents/crate-researcher.md 2. Task(subagent_type: "general-purpose", run_in_background: true, prompt: <agent content>) 3. Wait for agent 4. Summarize results ``` **Rust Changelog Query:** ``` User: "What's new in Rust 1.85?" Claude: 1. Read ../../agents/rust-changelog.md 2. Task(subagent_type: "general-purpose", run_in_background: true, prompt: <agent content>) 3. Wait for agent 4. Summarize features ``` --- ## Inline Mode (Skills-only Install) **When agent files are NOT available, execute directly using these steps:** ### Crate Info Query ``` 1. actionbook: mcp__actionbook__search_actions("lib.rs crate info") 2. Get action details: mcp__actionbook__get_action_by_id(<action_id>) 3. agent-browser CLI (or WebFetch fallback): - open "https://lib.rs/crates/{crate_name}" - get text using selector from actionbook - close 4. Parse and format output ``` **Output Format:** ```markdown ## {Crate Name} **Version:** {latest} **Description:** {description} **Features:** - `feature1`: description **Links:** - [docs.rs](https://docs.rs/{crate}) | [crates.io](https://crates.io/crates/{crate}) | [repo]({repo_url}) ``` ### Rust Version Query ``` 1. actionbook: mcp__actionbook__search_actions("releases.rs rust changelog") 2. Get action details for selectors 3. agent-browser CLI (or WebFetch fallback): - open "https://releases.rs/docs/1.{version}.0/" - get text using selector from actionbook - close 4. Parse and format output ``` **Output Format:** ```markdown ## Rust 1.{version} **Release Date:** {date} ### Language Features - Feature 1: description - Feature 2: description ### Library Changes - std::module: new API ### Stabilized APIs - `api_name`: description ``` ### Std Library Docs (std::*, Send, Sync, Arc, etc.) ``` 1. Construct URL: "https://doc.rust-lang.org/std/{path}/" - Traits: std/{module}/trait.{Name}.html - Structs: std/{module}/struct.{Name}.html - Modules: std/{module}/index.html 2. agent-browser CLI (or WebFetch fallback): - open <url> - get text "main .docblock" - close 3. Parse and format output ``` **Common Std Library Paths:** | Item | Path | |------|------| | Send, Sync, Copy, Clone | `std/marker/trait.{Name}.html` | | Arc, Mutex, RwLock | `std/sync/struct.{Name}.html` | | Rc, Weak | `std/rc/struct.{Name}.html` | | RefCell, Cell | `std/cell/struct.{Name}.html` | | Box | `std/boxed/struct.Box.html` | | Vec | `std/vec/struct.Vec.html` | | String | `std/string/struct.String.html` | **Output Format:** ```markdown ## std::{path}::{Name} **Signature:** ```rust {signature} ``` **Description:** {description} **Examples:** ```rust {example_code} ``` ``` ### Third-Party Crate Docs (tokio, serde, etc.) ``` 1. Construct URL: "https://docs.rs/{crate}/latest/{crate}/{path}" 2. agent-browser CLI (or WebFetch fallback): - open <url> - get text ".docblock" - close 3. Parse and format output ``` **Output Format:** ```markdown ## {crate}::{path} **Signature:** ```rust {signature} ``` **Description:** {description} **Examples:** ```rust {example_code} ``` ``` ### Clippy Lints ``` 1. agent-browser CLI (or WebFetch fallback): - open "https://rust-lang.github.io/rust-clippy/stable/" - search for lint name in page - get text ".lint-doc" for matching lint - close 2. Parse and format output ``` **Output Format:** ```markdown ## Clippy Lint: {lint_name} **Level:** {warn|deny|allow} **Category:** {category} **Description:** {what_it_checks} **Example (Bad):** ```rust {bad_code} ``` **Example (Good):** ```rust {good_code} ``` ``` --- ## Tool Chain Priority Both modes use the same tool chain order: 1. **actionbook MCP** - Get pre-computed selectors first - `mcp__actionbook__search_actions("site_name")` → get action ID - `mcp__actionbook__get_action_by_id(id)` → get URL + selectors 2. **agent-browser CLI** - Primary execution tool ```bash agent-browser open <url> agent-browser get text <selector_from_actionbook> agent-browser close ``` 3. **WebFetch** - Last resort only if agent-browser unavailable ### Fallback Principle (CRITICAL) ``` actionbook → agent-browser → WebFetch (only if agent-browser unavailable) ``` **DO NOT:** - Skip agent-browser because it's slower - Use WebFetch as primary when agent-browser is available - Block on WebFetch without trying agent-browser first --- ## Deprecated Patterns | Deprecated | Use Instead | Reason | |------------|-------------|--------| | WebSearch for crate info | Task + agent or inline mode | Structured data | | Direct WebFetch | actionbook + agent-browser | Pre-computed selectors | | Guessing version numbers | Always fetch from source | Prevents misinformation | ## Error Handling | Error | Cause | Solution | |-------|-------|----------| | Agent file not found | Skills-only install | Use inline mode | | actionbook unavailable | MCP not configured | Fall back to WebFetch | | agent-browser not found | CLI not installed | Fall back to WebFetch | | Agent timeout | Site slow/down | Retry or inform user | | Empty results | Selector mismatch | Report and use WebFetch fallback | ## Proactive Triggering This skill triggers AUTOMATICALLY when: - Any Rust crate name mentioned (tokio, serde, axum, sqlx, etc.) - Questions about "latest", "new", "version", "changelog" - API documentation requests - Dependency/feature questions **DO NOT use WebSearch for Rust crate info. Use agents or inline mode instead.**