docs: describe the search sources

The ``web_search`` bullet lists both sources, the fallback order and the
snippet, and says the tool needs a non-empty ``search_sources``.

AGENTS.md

@@ -103,7 +103,7 @@ Module-level `@tool` handlers. Call `set_workspace_root()` before use.
 - **`chat`**: human prompts as tools — `ask_user_line` / `ask_user_choice` / `ask_user_form` (shared `prompting` core); `wait` (line prompt with timeout; Enter disturbs). Container args are shape-checked (`tools/chat/shape.py`): a mis-typed string `options`/`fields` (or a non-string `question`) returns an explained error — `options="a, b"` used to iterate characters into a per-character menu. `wait`'s `duration` accepts numeric strings (`"5"` = 5s) and rejects booleans/text/containers.
 - **`todo`**: LIFO stack of **task groups** (not a queue of tasks) — `todo_push` creates one group of siblings; `todo_pop` removes the whole top group; `todo_update` by id; DFS breakdown push[T1,T2]→push[T1.1…]→pop→push[T2.1…]; stored on session row; open items = unfinished work (`[TODO OPEN WORK]`); all-terminal non-empty = hygiene (`[TODO HYGIENE]`); nag channel via `[agent] todo_nag_strategy` (`developer`/`user` = prose nag; `synthetic_tool` = forged `todo_list` call + **real** `stack.render()` result + ToolCall/Result events; `none`).
 - **`net` / `fetch`**: HTTP GET/POST/PUT/DELETE via niquests (isolated session, not the LLM client). Manual redirects with per-hop SSRF checks (`asyncio` `getaddrinfo`). Private/loopback hosts need instance policy grant (CLI timed confirm; **not** YOLO). Public cleartext HTTP and mutating methods soft-confirm (`YOLO`/`TRUSTABLE`). HTTPS→HTTP redirects blocked unless `allow_http_downgrade`. `user_agent` tool arg (or headers) is never replaced by the default when provided. Caps: body bytes/chars, request body size.
-- **`net` / `web_search`** (`tools/net/search.py`): the hosted search a DeepSeek provider cannot use, as a local tool. `build_web_search_tool(client, model=…)` closes over a `DeepseekSearchClient` (`lmproto/deepseek/anthropic/search.py`, a `/messages` turn carrying the server tool) and returns one `title — url` line per hit; the index keeps the page bodies, so the model reads a page with `fetch`. Registered by the CLI host only when `config.routing.local_web_search` says so: a DeepSeek provider whose `provider_tools` ask for `web_search` on a surface that ignores hosted tools (`convention` other than `anthropic`). Tags LOCAL|READ_ONLY.
+- **`net` / `web_search`** (`tools/net/search.py`, `tools/net/bing.py`): the hosted search a DeepSeek provider cannot use, as a local tool. `build_web_search_tool(backends)` closes over the sources named by `provider.search_sources` and asks them **in fallback order** (`search_in_order`): `DeepseekSearchBackend` (one `/messages` turn with the server tool, `lmproto/deepseek/anthropic/search.py`) and/or `BingSearchBackend` (Bing's RSS results, snippets included, fetched through the same client as `fetch`). The handler returns one `title — url` entry per hit (plus the snippet when the source has one); a source that raises or finds nothing is skipped and reported only if every source fails. Registered by the CLI host only when `config.routing.local_web_search` says so: a DeepSeek provider whose `provider_tools` ask for `web_search`, on a surface that ignores hosted tools (`convention` other than `anthropic`), with a non-empty `search_sources`. Tags LOCAL|READ_ONLY.
 - **`mcp`** (`tools/mcp.py`): register one server's advertised tools into the catalog as namespaced `mcp__<server>__<tool>` definitions with `ToolSource(kind="mcp", plugin_id=server)`; tags LOCAL (+ READ_ONLY when the server config sets `read_only`) — never YOLO/TRUSTABLE. `register_mcp_tools` purges prior MCP entries then re-registers every connected server (hosts call it on tool-registry rebuild); connections must already be started by `McpManager`.
 - **`skills`** (`tools/skills.py`): discovery, reading, and writing of skill directories (`plyngent.skills` owns roots, the `SKILL.md` frontmatter subset, the mtime-cached store, and the inside-the-skill path rule). `skill_list` (names, source root, directory, description, shadowed copies, frontmatter notes), `skill_read` (a `SKILL.md` by name, or one bundled file — reuses `read_file` for ranges/line numbers/`truncate_token`), `skill_search` (regex over every visible skill via `regex_files`, hits rebased on `<skill>/<file>`), `skill_create` (new `SKILL.md` + optional `files`), `skill_edit` (replace / `append` / rewrite one file; a rewritten `SKILL.md` is re-parsed and notes a lost description). Reads need no grant (the host publishes the roots as `WorkspacePolicy.static_read`, so `read_file`/`regex_files` see them while writes stay denied); writes go through **`SkillWritePolicy`** on the instance — denylist first, then `SessionState.skill_write_roots` (a `session` answer), then `[skills].allow_write`, then the host's confirm hook (CLI `prompt_skill_write_confirm`: `o`nce/`s`ession/`n`o, timed, default deny, **not** skipped by YOLO); a host with no hook denies. Grants are per **skill directory**; `[skills].enabled = false` drops the tools from the registry (`SKILL_TOOL_NAMES`).
 - **`DEFAULT_TOOLS` / catalog**: access + file + process + vcs + chat + todo + skills + net (`fetch`) for local surface. `ToolTag.READ_ONLY` marks non-mutating tools (`read_file`, `get_truncated`, `listdir`, `glob_paths`, `regex_files`, `tree`, `todo_list`, `wait`, `ask_user_*`, `vcs_*`, `skill_list`/`skill_read`/`skill_search`, `fetch`); `ToolRegistry.clone(read_only_only=True)` selects just those for safe side turns / planning, and `read_only_context()` (in `tools/context.py`) makes `fetch` accept GET only.