Step 3 gaps: file_edit tool, web_search tool, output scrubbing

[hackertron]

Context

Step 3 (Tool System) shipped with 5 built-in tools but the MVP spec calls for 8. Three items are missing.

Missing tools

file_edit (SideEffecting)

Find-and-replace edit in a file. The LLM specifies old text and new text, and the tool replaces it. More surgical than write_file for small changes.

Parameters:

• path (string, required) — file path
• old_text (string, required) — text to find
• new_text (string, required) — replacement text

web_search (SideEffecting)

Search the web. MVP supports DuckDuckGo (no API key needed), with Google and SearxNG as optional backends.

Parameters:

• query (string, required) — search query
• num_results (integer, optional, default 5) — number of results

Config already exists: tools.web_search.provider, tools.web_search.base_url, tools.web_search.api_key_env

Missing feature

Output scrubbing

Applied to all tool outputs before returning to LLM:

1. Path scrubbing — replace host absolute paths with workspace-relative paths
2. Keyword scrubbing — redact known secret patterns (API keys, tokens)
3. Entropy-based detection — flag high-entropy strings (Shannon >= 3.8)

Also noted in MVP but deferred

• WASM sandbox (wazero) — the MVP spec mentions it but process-mode tools work fine for launch. Can be added later for defense-in-depth.