The DuckDuckGo HTML fallback returns redirect URLs (//duckduckgo.com/l/?uddg=...)
instead of actual page URLs. This caused fetch_webpage_content() to reject them
instantly because _public_http_url() requires an http/https scheme, making search
results unfetchable in deep research mode.
Added _resolve_url() to:
- Convert protocol-relative URLs to absolute (https:)
- Convert path-relative URLs to absolute
- Extract the real URL from DuckDuckGo's /l/?uddg= redirect parameters
* fix: extract full year in research query entities, not just the century
* fix: same year capture-group bug in the services search copy
* test: research query extracts the full year
* feat(web-fetch): add web_fetch tool to read a specific URL's content
* test(web-fetch): add SSRF coverage and fail closed on empty DNS resolution
Add explicit SSRF regression tests for the web_fetch path covering
loopback, private LAN ranges, link-local/metadata, IPv6 private/local,
redirect-into-private, and unsupported schemes. Harden _public_http_url
to fail closed when a hostname resolves to no addresses.