web search via exa (spec-015): web_search tool, sanitized results, per-user cap, host-config key

2026-07-14 12:08:48 +02:00
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+# SPEC-015 — Web search (Exa)
+
+A `web_search` function tool for general "look it up on the internet"
+questions the other tools do not cover: IGDB is games, the Codex is
+Adeptus Mechanicus lore, the news store is the configured feeds, and
+`fetch_url` needs a URL the user already has. Web search fills the gap
+and pairs with `fetch_url` (search → pick a link → read it). Results are
+external text and are sanitized (SAF-03); the Exa key is a host secret,
+never in the repo. Active only when `enable-web-search = true` and a key
+is present.
+
+### WEB-01 — web_search is offered as a tool (coverage: test)
+
+When `enable-web-search` is true **and** an Exa key is available
+(`exa-api-key` in config, else `EXA_API_KEY` env), the chat call's
+`tools` list includes a `web_search` function (`query` string, optional
+`num_results`). With the flag off or no key it is absent.
+
+### WEB-02 — Results are reduced and sanitized (coverage: test)
+
+Each Exa result becomes `{title, url, snippet, published}`; `title` and
+`snippet` pass through `sanitize_external_text` (snippet capped at
+`web-snippet-chars`, default 400) so a web page can neither inject an
+`@everyone` nor smuggle control characters into the prompt.
+
+### WEB-03 — Result count is bounded (coverage: test)
+
+`num_results` is clamped to 1..`MAX_RESULTS` (10) before the request, so
+neither a huge fan-out nor a zero/negative count reaches the API.
+
+### WEB-04 — Missing key and API failure are reported, not raised (coverage: test)
+
+With no key the tool returns an `{error: ...}` result without a network
+call. A request that raises (network, non-2xx, bad JSON) is logged and
+returns an `{error: ...}` dict — `search` never raises into the loop.
+
+### WEB-05 — Searches are metered per user (coverage: test)
+
+Each `web_search` increments a per-user daily counter; over
+`web-daily-per-user` (default 30) the tool refuses with an error result
+without calling the API. The budget gate (SAF-04) still applies to the
+surrounding model calls.