Migrates Exa from the inline `_exa_search()` / `_exa_extract()` helpers in
tools/web_tools.py to a bundled plugin at plugins/web/exa/.
This is the first plugin in this PR to advertise supports_extract=True,
exercising the multi-capability ABC path that the initial three migrations
(brave_free, ddgs, searxng — all search-only) did not cover.
Both Exa methods are sync — the SDK is sync-only. The web_extract_tool
dispatcher in tools/web_tools.py will continue to call them inline until
Task "dispatch-extract-all" cuts it over to the registry.
Behaviour preserved bit-for-bit aside from the ABC method-name change:
- is_configured() -> is_available()
- provider_name() -> name (property)
- "exa" stays as the registered name
- Module-level `_exa_client` cache + lazy `from exa_py import Exa`
preserved at the new location.
- Errors (ValueError for missing API key, ImportError for missing SDK,
generic Exception) caught and surfaced as {"success": False, "error": ...}
instead of raising.
Adds "exa" to _WEB_PLUGIN_SKIPLIST in hermes_cli/tools_config.py so the
hardcoded TOOL_CATEGORIES["web"] row and the plugin-injected row don't
duplicate during the spike. The skip-list goes away in the cleanup phase
along with the hardcoded row.
The legacy inline `_exa_search` / `_exa_extract` / `_get_exa_client` /
`_exa_client` in tools/web_tools.py are NOT deleted yet — the dispatcher
still references them. They go away in the next dispatcher-cutover commit.
E2E verified:
- Plugin discovers + registers
- .supports_search/.supports_extract/.supports_crawl = (True, True, False)
- .get_setup_schema() returns the picker row shape
- resolve(): explicit exa + EXA_API_KEY -> exa; without key -> exa (registered
but unavailable, dispatcher surfaces "EXA_API_KEY not set" error)
