refactor pi resource wiring by directory

pi/extensions/exa-tools/README.md

@@ -0,0 +1,55 @@
+# pi exa-tools scaffold
+
+Global pi extension that adds Exa-backed retrieval tools.
+
+## Tools
+
+- `exa_search` — general web/docs/reference search
+- `exa_code` — coding context and open-source implementation examples
+
+## Mental model
+
+- use `exa_search` for official docs, release notes, blog posts, issues, comparisons, and general web research
+- use `exa_code` for library usage, framework patterns, API examples, and code-specific prior art
+
+## Credentials
+
+The extension looks for credentials in this order:
+
+1. `EXA_API_KEY`
+2. `~/.config/secrets/exa-api-key`
+3. `~/.config/secrets/exa_api_key`
+
+If none are found, the tools throw a helpful error.
+
+Note: the Exa account also needs available credits. A valid key with no remaining credits will still fail at request time.
+
+## Command
+
+- `/exa-tools` — show credential status and available tools
+
+## Installation
+
+This repo deploys the extension declaratively through Home Manager to:
+
+```text
+~/.pi/agent/extensions/exa-tools
+```
+
+## Example usage
+
+General web research:
+
+```text
+Use exa_search to find the official docs for Exa context search
+```
+
+Coding context:
+
+```text
+Use exa_code to find examples of React hook state management patterns
+```
+
+Subagent usage:
+
+The `librarian` subagent can use these tools once the extension is globally installed.