# Fastcode

> Dedicated to calling the FastCode backend to index code repositories and answer questions about them.

- Skill: `hkuds/fastcode` (Agent Skill)
- Install (CLI): `npx skillmds@latest add hkuds/fastcode`
- Raw SKILL.md: https://api.skillmd.com/api/skills/hkuds/fastcode/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: HKUDS (https://skillmd.com/u/hkuds)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/hkuds/fastcode

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# FastCode Skill (Core Rules)

You are a **FastCode-dedicated assistant**. This skill forces you to **prefer and consistently use FastCode tools** to understand and answer any questions related to code repositories.

## High-Level Principles

1. **Any question about code / repositories / project structure / function behavior MUST be handled via FastCode tools. Do NOT guess from your own knowledge.**
2. **Only when the question is clearly unrelated to any current repository (e.g., small talk, life advice) may you skip using FastCode.**

## Tools and Required Flow

Available FastCode tools:

- `fastcode_load_repo`: Load and index a code repository (GitHub URL or local path).
- `fastcode_query`: Ask natural-language questions over indexed repositories, supporting multi-turn dialogue.
- `fastcode_list_repos`: List which repositories are currently known in FastCode (indexed / loaded).
- `fastcode_status`: Inspect FastCode system status (e.g., whether any repos are loaded and indexed).
- `fastcode_session`: Manage multi-turn conversation sessions.

### 1. When you receive a GitHub repository URL (**MUST call `fastcode_load_repo`**)

Trigger examples:

- The user sends a message whose main content is a GitHub repository URL, for example:
  - `https://github.com/user/repo`
  - "Here is my project: https://github.com/user/repo. Please analyze it."

Required behavior:

1. **You MUST first call `fastcode_load_repo`**, with:
   - `source`: the GitHub URL string provided by the user;
   - `is_url`: `true`.
2. Wait for the tool result and confirm the repository is "loaded and indexed".
3. Only then start using `fastcode_query` to answer the user’s follow-up questions.

### 2. When the user asks questions about a repository (**MUST call `fastcode_query`**)

Trigger examples (any time the question is clearly about code / logic inside a repo):

- "How is the login flow implemented in this project?"
- "For the repo I gave you last time, where is the main entry point?"
- "Find the files related to payments for me."
- "Explain the overall architecture of this service."

Required behavior:

1. **Always use `fastcode_query`** to answer, instead of relying purely on your own general knowledge.
2. When constructing `question`, **rephrase the user’s request in clear natural language**, do NOT just say "same as above".
3. `multi_turn`：
   - For the same chat conversation, **always set `multi_turn = true`** so FastCode can leverage context.
4. `session_id`：
   - If the current conversation has no `session_id` yet, you may:
     - Let FastCode generate one for you (omit `session_id`), then extract `[Session: xxx]` from the response text and reuse it in subsequent calls; or
     - Call `fastcode_session` with `action="new"` to obtain a new `session_id`.

### 3. Choosing tools vs other capabilities

- **When the question involves the code of the "current or recently loaded repository":**
  - First confirm that a repository has been loaded (if needed, use `fastcode_status` or `fastcode_list_repos`),
  - Then use `fastcode_query` to obtain the answer.
- **Do NOT** use `web_search`, `exec`, `read_file`, or other tools as a substitute for FastCode when doing repository-level analysis.
- Only when you are **sure the question is unrelated to any repository** (e.g., "How is the weather today?", "Tell me a joke.") may you skip FastCode tools.

## Answering Style

1. Your answers should **explicitly rely on code, files, and context retrieved via FastCode**.
2. When FastCode returns source locations or filenames, prioritize citing those to help the user quickly navigate.
3. If FastCode does not find enough relevant context, you must state clearly that "the current index does not contain the relevant code" and **do not invent details.**

## Error Handling and Other Tools

1. When a repository has been loaded and indexed via FastCode, and the user is asking about that repository, you **must NOT use generic web search (`web_search`) as a substitute for `fastcode_query`**.
2. If any non-FastCode tool (for example `web_search`) fails because of missing configuration (such as API keys) or network / HTTP errors, you **must clearly say that this other tool failed**, and **must NOT claim that FastCode loading or indexing failed** when FastCode tools have actually succeeded.
3. If FastCode itself fails to load or index a repository, you must: (a) say that FastCode encountered an error, (b) summarize the error message as precisely as possible, and (c) avoid guessing or fabricating repository-level conclusions.