Factor tool definitions out of assistant (#21189)

This PR factors the tool definitions out of the `assistant` crate so
that they can be shared between `assistant` and `assistant2`.

`ToolWorkingSet` now lives in `assistant_tool`. The tool definitions
themselves live in `assistant_tools`, with the exception of the
`ContextServerTool`, which has been moved to the `context_server` crate.

As part of this refactoring I needed to extract the
`ContextServerSettings` to a separate `context_server_settings` crate so
that the `extension_host`—which is referenced by the `remote_server`—can
name the `ContextServerSettings` type without pulling in some undesired
dependencies.

Release Notes:

- N/A

crates/assistant_tools/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "assistant_tools"
+version = "0.1.0"
+edition = "2021"
+publish = false
+license = "GPL-3.0-or-later"
+
+[lints]
+workspace = true
+
+[lib]
+path = "src/assistant_tools.rs"
+
+[dependencies]
+anyhow.workspace = true
+assistant_tool.workspace = true
+chrono.workspace = true
+gpui.workspace = true
+schemars.workspace = true
+serde.workspace = true
+serde_json.workspace = true
+workspace.workspace = true

crates/assistant_tools/LICENSE-GPL

@@ -0,0 +1 @@
+../../LICENSE-GPL

crates/assistant_tools/src/assistant_tools.rs

@@ -0,0 +1,13 @@
+mod now_tool;
+
+use assistant_tool::ToolRegistry;
+use gpui::AppContext;
+
+use crate::now_tool::NowTool;
+
+pub fn init(cx: &mut AppContext) {
+    assistant_tool::init(cx);
+
+    let registry = ToolRegistry::global(cx);
+    registry.register_tool(NowTool);
+}

crates/assistant_tools/src/now_tool.rs

@@ -0,0 +1,60 @@
+use std::sync::Arc;
+
+use anyhow::{anyhow, Result};
+use assistant_tool::Tool;
+use chrono::{Local, Utc};
+use gpui::{Task, WeakView, WindowContext};
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Serialize, Deserialize, JsonSchema)]
+#[serde(rename_all = "snake_case")]
+pub enum Timezone {
+    /// Use UTC for the datetime.
+    Utc,
+    /// Use local time for the datetime.
+    Local,
+}
+
+#[derive(Debug, Serialize, Deserialize, JsonSchema)]
+pub struct FileToolInput {
+    /// The timezone to use for the datetime.
+    timezone: Timezone,
+}
+
+pub struct NowTool;
+
+impl Tool for NowTool {
+    fn name(&self) -> String {
+        "now".into()
+    }
+
+    fn description(&self) -> String {
+        "Returns the current datetime in RFC 3339 format.".into()
+    }
+
+    fn input_schema(&self) -> serde_json::Value {
+        let schema = schemars::schema_for!(FileToolInput);
+        serde_json::to_value(&schema).unwrap()
+    }
+
+    fn run(
+        self: Arc<Self>,
+        input: serde_json::Value,
+        _workspace: WeakView<workspace::Workspace>,
+        _cx: &mut WindowContext,
+    ) -> Task<Result<String>> {
+        let input: FileToolInput = match serde_json::from_value(input) {
+            Ok(input) => input,
+            Err(err) => return Task::ready(Err(anyhow!(err))),
+        };
+
+        let now = match input.timezone {
+            Timezone::Utc => Utc::now().to_rfc3339(),
+            Timezone::Local => Local::now().to_rfc3339(),
+        };
+        let text = format!("The current datetime is {now}.");
+
+        Task::ready(Ok(text))
+    }
+}