docs: describe the local search tool

The tools list gains the ``web_search`` entry (what it returns, when the CLI
registers it), and the provider-tools bullet says DeepSeek's preset asks for no
hosted tool by default.

AGENTS.md

@@ -79,7 +79,7 @@ Async SQLAlchemy + aiosqlite. `MemoryStore`: schema init (+ lightweight SQLite `
 - **Kind-based dispatch**: clients expose `kind` (`chat_completions` | `responses` | `messages`). Agent history stays chat-completions-shaped; transport adapters return synthetic `ChatCompletionResponse` / stream chunks.
 - **`responses_bridge` / `responses_dispatch`**: chat ↔ OpenAI Responses; stream text/reasoning deltas; tool calls + usage on `response.completed`; a request carrying `tools` returns every round's reasoning as a `reasoning` item of `reasoning_text` parts — "必须完整回传 `reasoning_content` … 即使该轮模型未实际进行工具调用" (a missing item and an empty part are both a 400, so a round that kept none sends a blank line) — and a round's `function_call` items stay contiguous ahead of their outputs (`call, output, call, output` was a 400: the second call reads as a round of its own without reasoning); reasoning is read back from the item's `content` parts.
 - **`messages_bridge` / `messages_dispatch`**: chat ↔ Anthropic Messages; system fold; tool_use/tool_result; stream text + tool argument fragments; `thinking` from the request's `reasoning_effort` (level → token budget, floor 1024, `max_tokens` grown when the budget would leave no room) plus the client's configured `thinking_budget_tokens`; a server tool (`server_tool_use` + its `web_search_tool_result`) is the surface's own business — it streams `input_json_delta` fragments like a call but nothing local asked for it, so only a `tool_use` block becomes a tool call, and the blocks are read (see `lmproto/anthropic/model.py`) but never executed.
-- **Provider-side tools**: `OpenAIProvider.provider_tools` (list of dicts; default `[{type="web_search"}]` when omitted; `[]` disables) threaded via `ChatAgent`/`run_chat_loop` into Responses and Messages; never executed by `ToolRegistry`. The Messages surface declares its own server tool instead — a bare `web_search` becomes `{type="web_search_20250305", name="web_search"}` (the search then runs inside the response, and its `encrypted_content` results must be passed back verbatim if they are kept at all).
+- **Provider-side tools**: `OpenAIProvider.provider_tools` (list of dicts; default `[{type="web_search"}]` when omitted; `[]` disables; DeepSeek's preset defaults to none, so search is opt-in there) threaded via `ChatAgent`/`run_chat_loop` into Responses and Messages; never executed by `ToolRegistry`. The Messages surface declares its own server tool instead — a bare `web_search` becomes `{type="web_search_20250305", name="web_search"}` (the search then runs inside the response, and its `encrypted_content` results must be passed back verbatim if they are kept at all) — and a DeepSeek provider on a surface that ignores hosted tools (`config.routing.local_web_search`) gets the local `web_search` tool from `tools/net/search.py` instead.
 - **`@tool` / `ToolRegistry`**: decorator infers JSON Schema from type hints; execute tools by name. Before running, `execute` answers a call that omits a required argument with the accepted names (`_missing_required_error`) — the handler's bare `TypeError` never reaches the model, and no confirm prompt fires for a call that cannot run. Shape mistakes inside a *present* argument are the tool's own job (see the `chat` bullet).
 - **`run_chat_loop`**: multi-round tool loop; default **streaming** text deltas + stream tool-call merge; parallel tools; tool-result char budget; soft context compact on request (**API-calibrated** after first usage when available); cooperative cancel points; optional `on_limit`; resolved `reasoning_effort` on every request (see Config).
 - **`ChatAgent`**: optional `MemoryStore` (user message persisted immediately; **completed tool batches checkpointed** mid-turn; unfinished assistant suffix rolled back on failure); `stream`; system prompt; `provider_tools`; `retry()` continues incomplete turns (user-only **or** after committed tools — does not re-run those tools).
@@ -103,6 +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.
 - **`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.