SurfSense/plans/backend/04b-source-discovery.md

Phase 4b — Web-search repurposing + source-discovery endpoint

Part of Phase 4 — Connector two-type restructure (backend). See 00-umbrella-plan.md. Sibling: 04a-connector-category.md. Best sequenced after 04a (taxonomy in place). Precondition: Phases 1–2 (rename) live.

Implementation note. Phases 1–2 are SHIPPED, so the live code already says workspace_id/Workspace — substitute for the old search_space_*/SearchSpace names in citations below and grep the new name; locate code by symbol/grep, not the absolute line numbers cited.

Objective

Retire the five web-search connector types and re-cast the survivors as platform-level providers that power two things: (1) the existing chat web_search tool, and (2) a new source-discovery endpoint that, given a topic/competitor, suggests candidate URLs the user can feed into the Universal WebURL Crawler / a pipeline.

Resolved decisions driving this:

• Drop all 5 search connector_type enum values (SERPER_API, TAVILY_API, SEARXNG_API, LINKUP_API, BAIDU_SEARCH_API).
• Tavily + Serper removed entirely (no provider, no code path).
• SearXNG / Linkup / Baidu survive as platform providers. SearXNG is already platform/env-based; Linkup + Baidu move from per-workspace connector config to platform/env config (one app-wide key set, matching the "single provider app-wide" style from 03b).

Current state (cited)

The 5 search types are first-class connectors today

• Enum members SERPER_API/TAVILY_API/SEARXNG_API/LINKUP_API/BAIDU_SEARCH_API — db.py:86–90 (SERPER_API is annotated "NOT IMPLEMENTED YET"; SearXNG is already platform-backed despite being an enum value).
• Per-workspace search methods on ConnectorService read keys from the connector row's config: search_tavily (connector_service.py:481, key TAVILY_API_KEY:510), search_searxng (:587), search_baidu (:614), search_linkup (:1968, key LINKUP_API_KEY:2000).
• Query-time routing: connector_searchable_types.py:_CONNECTOR_TYPE_TO_SEARCHABLE (:22–26) maps TAVILY_API/LINKUP_API/BAIDU_SEARCH_API to the web_search tool ("live search connectors"); the other connector types map to KB pre-search.

The web_search tool already has a platform/per-workspace split

Post-main-merge note. A main sync consolidated web_search to a single tool: the old research-subagent copy subagents/builtins/research/tools/web_search.py was deleted, and there is now one factory at app/agents/chat/shared/tools/web_search.py. The research subagent now imports it (subagents/builtins/research/tools/index.py:10,24–26). So everywhere below that said "both variants / mirror" is now one file. The same merge also retired the XML result blob in favor of [n]-citation rendering (see §3).

web_search tool factory create_web_search_tool(search_space_id, available_connectors) — the single canonical tool at app/agents/chat/shared/tools/web_search.py:

• _LIVE_SEARCH_CONNECTORS = {TAVILY_API, LINKUP_API, BAIDU_SEARCH_API} (:41–45), _LIVE_CONNECTOR_SPECS → ConnectorService.search_* (:47–51), per-connector dispatch _search_live_connector (:115–151). The factory picks the active live connectors by intersecting available_connectors with _LIVE_SEARCH_CONNECTORS (:163–167).
• At call time it fans out in parallel to platform SearXNG (web_search_service.is_available() / .search(), :204–214) plus each active per-workspace live connector (:216–228), then dedupes by URL (:242–250).
• Platform SearXNG service: app/services/web_search_service.py — env-gated by config.SEARXNG_DEFAULT_HOST, in-process circuit breaker + Redis result cache; returns the (result_obj, documents) shape the tool consumes.

Config

• config.SEARXNG_DEFAULT_HOST = os.getenv("SEARXNG_DEFAULT_HOST") — config/__init__.py:558. There are no platform env vars for Linkup/Baidu/Tavily today (their keys live in connector config).

Target design

1. Platform search-provider config (env)

Add platform env knobs alongside SEARXNG_DEFAULT_HOST (config/__init__.py:~558):

• LINKUP_API_KEY = os.getenv("LINKUP_API_KEY")
• BAIDU_SEARCH_API_KEY = os.getenv("BAIDU_SEARCH_API_KEY") (+ the optional knobs search_baidu reads from connector config today — BAIDU_MODEL / BAIDU_SEARCH_SOURCE / BAIDU_ENABLE_DEEP_SEARCH, per validators.py:507-514; the required key is BAIDU_API_KEY in the per-workspace config, relocated to this platform env var — port from its current config reads).
• (SearXNG unchanged.) Document all three in .env.example as optional; each provider self-disables when its key/host is unset (mirrors web_search_service.is_available()).

No Tavily/Serper env (removed).

2. A platform search-providers service (consolidate the survivors)

Introduce app/services/web_search_service.py-level functions (or a small search_providers/ package) so all three survivors share one platform shape (result_obj, documents):

• searxng.search(...) — the existing web_search_service.search (unchanged).
• linkup.search(...) / baidu.search(...) — port the bodies of ConnectorService.search_linkup/search_baidu but source the API key from config.* (platform) instead of connector.config (per-workspace), and drop the search_space_id/connector lookups.
• Each is is_available()-gated on its env key. Tavily (search_tavily) is deleted.

This removes per-workspace coupling: web search + discovery no longer depend on any connector row.

3. Rewire the chat web_search tool (single tool)

• Drop the _LIVE_SEARCH_CONNECTORS / _LIVE_CONNECTOR_SPECS / _search_live_connector mechanism in the single tool shared/tools/web_search.py (:41–51, :115–151, and the factory's live-connector intersection :163–167, plus the per-workspace fan-out :216–228). Instead, fan out to the platform providers that are is_available() (SearXNG + Linkup + Baidu), all keyless from the caller's view.
• Keep the existing parallel-gather + URL-dedupe (:233–250). Note: the main merge replaced the old XML result blob with [n]-citation rendering — the tool now builds RenderableDocuments (_to_renderable_web_documents:66–112) and returns them via render_web_results + load_registry, persisting the citation_registry on state (:252–281). Leave that render/registry path unchanged; only the provider sourcing (SearXNG+Linkup+Baidu, env-keyed) changes.
• Call-site churn — keep the available_connectors parameter in the factory signature but stop using it for provider selection (providers are now env-derived). This avoids touching every caller: main_agent/tools/registry.py:24,39, subagents/builtins/research/tools/index.py:10,24–26, and anonymous_chat/agent.py:127 (passes available_connectors=None already). deliverables is no longer a web_search caller (its KB/web tooling was removed in the main merge) — drop it from the churn list. search_space_id likewise stays for logging only. (A later cleanup can remove the now-dead params.)
• Net behaviour: web search works platform-wide whenever any provider env key is set; it no longer requires the workspace to have a search connector configured (so anonymous chat gains web search too).

4. Source-discovery endpoint (the new capability)

New route (e.g. routes/source_discovery_routes.py, mounted under /api/v1/workspaces/{workspace_id}/... to match the renamed surface): POST .../source-discovery taking { query/topic, top_k } and returning a ranked list of candidate URLs (url, title, snippet, provider) for the user to add to the WebURL Crawler / a pipeline.

• Implementation = call the platform providers (§2) in parallel, dedupe by URL (reuse the tool's dedupe), and return URL-centric results (plain {url,title,snippet,provider} — not the chat tool's [n]-cited render_web_results output, which is for in-conversation citation, not URL suggestion).
• Auth: standard workspace access check (same dependency as other workspace routes).
• This is backend-only; the UX (a "find sources" affordance when configuring a crawler/pipeline) is deferred to the frontend umbrella.
• Optional thin reuse: the chat web_search _web_search_impl and this endpoint can share a discover_urls(query, top_k) -> list[UrlCandidate] core.

5. Drop the 5 connector types

• Remove the enum members SERPER_API/TAVILY_API/SEARXNG_API/LINKUP_API/BAIDU_SEARCH_API from SearchSourceConnectorType (db.py:86–90).
• Remove their connector code paths: ConnectorService.search_tavily (:481, delete) and the per-workspace search_searxng (:587)/search_baidu (:614)/search_linkup (:1968) (replace with the platform service §2; delete the connector-config variants that read connector.config[...]_API_KEY, e.g. :510, :2000). Remove the three search entries from connector_searchable_types.py:24–26. Remove the *_API entries from the connector-config validation dict (utils/validators.py:490–514, the 5 keys in connector_rules: SERPER_API:490/TAVILY_API:491/SEARXNG_API:492-505/LINKUP_API:506/BAIDU_SEARCH_API:507-514) and 04a's HIDDEN registry entries for these types. Grep-guard: no remaining references to the 5 enum names or search_tavily anywhere.
• Migration (this phase is NOT migration-free): existing connector rows of these 5 types must be handled before/with the enum change:
  • Alembic migration: DELETE FROM search_source_connectors WHERE connector_type IN ('SERPER_API','TAVILY_API','SEARXNG_API','LINKUP_API','BAIDU_SEARCH_API'); (FKs cascade; these rows only held search API keys, now relocated to env). Self-hosted operators re-add Linkup/Baidu keys via env — call out in the migration docstring + .env.example.
  • PG enum handling: dropping a value from a Postgres enum type requires a type recreate. Lowest-risk option: after deleting the rows, leave the now-unused labels in the PG enum type (harmless orphans) and just remove them from the Python StrEnum so no new rows can use them. If a clean type is wanted, do the standard "create new enum → ALTER COLUMN ... TYPE with a USING cast → drop old" dance in the migration (heavier; only if desired). Recommend the orphan-label approach for MVP.
  • Also scrub document.document_type / search rows that referenced TAVILY_API/LINKUP_API/BAIDU_SEARCH_API as a doc type only if such persisted docs exist (live-search results were ephemeral, not indexed — verify; expectation is none).

Work items

1. Config: LINKUP_API_KEY, BAIDU_SEARCH_API_KEY (+ Baidu host/region) in Config + .env.example; keep SEARXNG_DEFAULT_HOST.
2. Platform providers: port Linkup/Baidu search to env-keyed platform functions sharing SearXNG's (result_obj, documents) shape; delete Tavily.
3. Rewire web_search (the single shared tool shared/tools/web_search.py) to fan out to platform providers; drop available_connectors/live-connector plumbing; keep dedupe + the [n]-citation render path.
4. Source-discovery endpoint: POST .../source-discovery → ranked URL candidates; shared discover_urls() core.
5. Drop the 5 enum values + remove search_* connector methods, connector_searchable_types search entries, validators, and 04a HIDDEN entries.
6. Migration: delete the 5 connector types' rows; handle the PG enum (orphan-label approach); docstring notes the env re-keying.
7. Tests (below).

Tests

• Provider availability: each of SearXNG/Linkup/Baidu self-disables when its env key/host is unset; web_search returns "not available" only when all are unset.
• web_search rewire: with LINKUP_API_KEY set (no search connector rows), web_search still returns Linkup results; results from multiple providers dedupe by URL.
• No per-workspace dependency: a workspace with zero connectors still gets web search + source-discovery results.
• Source-discovery endpoint: returns URL candidates {url,title,snippet,provider}; enforces workspace access; empty when no providers configured.
• Enum removal: SearchSourceConnectorType no longer has the 5 values; creating one → 422; the migration deletes existing rows; reading remaining connectors is unaffected.
• Tavily gone: no import/path references search_tavily/TAVILY_API remain (grep guard).

Risks / trade-offs

• Per-workspace search keys become platform-wide (accepted). Workspaces can no longer bring their own Linkup/Baidu keys; one app-wide key set serves everyone (matches the single-provider posture). Self-hosted must move keys to env — surfaced in migration docs.
• Destructive migration. Deleting the 5 connector types' rows is irreversible (downgrade can recreate rows but not their secrets). Gate behind the standard backup/runbook; the data is just API-key config now living in env.
• PG enum orphan labels. Leaving unused enum labels is cosmetically untidy but avoids a risky type-recreate; documented as a deliberate trade-off.
• Sequencing with 04a. 04a marks the 5 types HIDDEN so the taxonomy stays total in the interim; 04b removes them. If 04b ships first, 04a's HIDDEN bucket is simply never populated — both orders are safe, but 04a → 04b is the intended order.

Out of scope (hand-offs)

• Taxonomy/gating/MCP-routing fix → 04a.
• Using discovered URLs to actually create a pipeline/crawl → Phases 5–7 (this endpoint only suggests URLs).
• Source-discovery UX (the "find sources" affordance) → frontend umbrella.
• Crawl billing for any crawl the user starts from a discovered URL → already covered by 03c (the crawl path bills regardless of how the URL was found).